From 6ed8f5151719fbc14ec0ac6d28a346d1f74cf2ca Mon Sep 17 00:00:00 2001
From: Joel Klinghed <the_jk@spawned.biz>
Date: Fri, 2 Jan 2026 22:42:31 +0100
Subject: Initial commit

---
 .clang-format           | 315 ++++++++++++++++
 .clang-tidy             |   2 +
 .dir-locals.el          |  13 +
 .gitignore              |   1 +
 meson.build             | 373 +++++++++++++++++++
 src/args.cc             | 389 ++++++++++++++++++++
 src/args.hh             |  64 ++++
 src/cfg.cc              | 199 ++++++++++
 src/cfg.hh              |  45 +++
 src/check.hh            |  39 ++
 src/colour.cc           |  15 +
 src/colour.hh           |  20 +
 src/config.h.in         |   6 +
 src/image.cc            |  15 +
 src/image.hh            |  62 ++++
 src/image_loader.hh     |  15 +
 src/image_processor.cc  | 947 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/image_processor.hh  |  29 ++
 src/io.cc               | 358 ++++++++++++++++++
 src/io.hh               | 109 ++++++
 src/line.cc             | 127 +++++++
 src/line.hh             |  37 ++
 src/logger.cc           | 125 +++++++
 src/logger.hh           |  41 +++
 src/main.cc             |  47 +++
 src/paths.cc            | 100 +++++
 src/paths.hh            |  20 +
 src/size.hh             |  30 ++
 src/spawner.cc          | 236 ++++++++++++
 src/spawner.hh          |  49 +++
 src/str.cc              |  94 +++++
 src/str.hh              |  34 ++
 src/u.hh                |  21 ++
 src/u8.hh               | 196 ++++++++++
 src/unique_fd.cc        |   9 +
 src/unique_fd.hh        |  36 ++
 src/xpm/.clang-tidy     |   2 +
 src/xpm/color.c         | 882 ++++++++++++++++++++++++++++++++++++++++++++
 src/xpm/dix-config.h    |   1 +
 src/xpm/dix/dix_priv.h  |  14 +
 src/xpm/include/dix.h   |  14 +
 subprojects/.gitignore  |   3 +
 subprojects/gtest.wrap  |  16 +
 test/args.cc            | 412 +++++++++++++++++++++
 test/cfg.cc             | 190 ++++++++++
 test/data/test.jpeg     | Bin 0 -> 734 bytes
 test/data/test.png      | Bin 0 -> 171 bytes
 test/data/test.svg      |  62 ++++
 test/data/test.xpm      |  17 +
 test/image_processor.cc | 251 +++++++++++++
 test/io.cc              | 274 ++++++++++++++
 test/io_test_helper.cc  | 165 +++++++++
 test/io_test_helper.hh  |  27 ++
 test/line.cc            | 182 ++++++++++
 test/paths.cc           |  63 ++++
 test/str.cc             | 164 +++++++++
 test/testdir.cc         |  37 ++
 test/testdir.hh         |  22 ++
 test/testenv.cc         |  44 +++
 test/testenv.hh         |  22 ++
 test/u8.cc              | 276 ++++++++++++++
 61 files changed, 7358 insertions(+)
 create mode 100644 .clang-format
 create mode 100644 .clang-tidy
 create mode 100644 .dir-locals.el
 create mode 100644 .gitignore
 create mode 100644 meson.build
 create mode 100644 src/args.cc
 create mode 100644 src/args.hh
 create mode 100644 src/cfg.cc
 create mode 100644 src/cfg.hh
 create mode 100644 src/check.hh
 create mode 100644 src/colour.cc
 create mode 100644 src/colour.hh
 create mode 100644 src/config.h.in
 create mode 100644 src/image.cc
 create mode 100644 src/image.hh
 create mode 100644 src/image_loader.hh
 create mode 100644 src/image_processor.cc
 create mode 100644 src/image_processor.hh
 create mode 100644 src/io.cc
 create mode 100644 src/io.hh
 create mode 100644 src/line.cc
 create mode 100644 src/line.hh
 create mode 100644 src/logger.cc
 create mode 100644 src/logger.hh
 create mode 100644 src/main.cc
 create mode 100644 src/paths.cc
 create mode 100644 src/paths.hh
 create mode 100644 src/size.hh
 create mode 100644 src/spawner.cc
 create mode 100644 src/spawner.hh
 create mode 100644 src/str.cc
 create mode 100644 src/str.hh
 create mode 100644 src/u.hh
 create mode 100644 src/u8.hh
 create mode 100644 src/unique_fd.cc
 create mode 100644 src/unique_fd.hh
 create mode 100644 src/xpm/.clang-tidy
 create mode 100644 src/xpm/color.c
 create mode 100644 src/xpm/dix-config.h
 create mode 100644 src/xpm/dix/dix_priv.h
 create mode 100644 src/xpm/include/dix.h
 create mode 100644 subprojects/.gitignore
 create mode 100644 subprojects/gtest.wrap
 create mode 100644 test/args.cc
 create mode 100644 test/cfg.cc
 create mode 100644 test/data/test.jpeg
 create mode 100644 test/data/test.png
 create mode 100644 test/data/test.svg
 create mode 100644 test/data/test.xpm
 create mode 100644 test/image_processor.cc
 create mode 100644 test/io.cc
 create mode 100644 test/io_test_helper.cc
 create mode 100644 test/io_test_helper.hh
 create mode 100644 test/line.cc
 create mode 100644 test/paths.cc
 create mode 100644 test/str.cc
 create mode 100644 test/testdir.cc
 create mode 100644 test/testdir.hh
 create mode 100644 test/testenv.cc
 create mode 100644 test/testenv.hh
 create mode 100644 test/u8.cc

diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..aa4a4dc
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,315 @@
+---
+Language:        Cpp
+AccessModifierOffset: -1
+AlignAfterOpenBracket: Align
+AlignArrayOfStructures: None
+AlignConsecutiveAssignments:
+  Enabled:         false
+  AcrossEmptyLines: false
+  AcrossComments:  false
+  AlignCompound:   false
+  AlignFunctionDeclarations: false
+  AlignFunctionPointers: false
+  PadOperators:    true
+AlignConsecutiveBitFields:
+  Enabled:         false
+  AcrossEmptyLines: false
+  AcrossComments:  false
+  AlignCompound:   false
+  AlignFunctionDeclarations: false
+  AlignFunctionPointers: false
+  PadOperators:    false
+AlignConsecutiveDeclarations:
+  Enabled:         false
+  AcrossEmptyLines: false
+  AcrossComments:  false
+  AlignCompound:   false
+  AlignFunctionDeclarations: true
+  AlignFunctionPointers: false
+  PadOperators:    false
+AlignConsecutiveMacros:
+  Enabled:         false
+  AcrossEmptyLines: false
+  AcrossComments:  false
+  AlignCompound:   false
+  AlignFunctionDeclarations: false
+  AlignFunctionPointers: false
+  PadOperators:    false
+AlignConsecutiveShortCaseStatements:
+  Enabled:         false
+  AcrossEmptyLines: false
+  AcrossComments:  false
+  AlignCaseArrows: false
+  AlignCaseColons: false
+AlignConsecutiveTableGenBreakingDAGArgColons:
+  Enabled:         false
+  AcrossEmptyLines: false
+  AcrossComments:  false
+  AlignCompound:   false
+  AlignFunctionDeclarations: false
+  AlignFunctionPointers: false
+  PadOperators:    false
+AlignConsecutiveTableGenCondOperatorColons:
+  Enabled:         false
+  AcrossEmptyLines: false
+  AcrossComments:  false
+  AlignCompound:   false
+  AlignFunctionDeclarations: false
+  AlignFunctionPointers: false
+  PadOperators:    false
+AlignConsecutiveTableGenDefinitionColons:
+  Enabled:         false
+  AcrossEmptyLines: false
+  AcrossComments:  false
+  AlignCompound:   false
+  AlignFunctionDeclarations: false
+  AlignFunctionPointers: false
+  PadOperators:    false
+AlignEscapedNewlines: Left
+AlignOperands:   Align
+AlignTrailingComments:
+  Kind:            Always
+  OverEmptyLines:  0
+AllowAllArgumentsOnNextLine: true
+AllowAllParametersOfDeclarationOnNextLine: true
+AllowBreakBeforeNoexceptSpecifier: Never
+AllowShortBlocksOnASingleLine: Never
+AllowShortCaseExpressionOnASingleLine: true
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortCompoundRequirementOnASingleLine: true
+AllowShortEnumsOnASingleLine: true
+AllowShortFunctionsOnASingleLine: All
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLambdasOnASingleLine: All
+AllowShortLoopsOnASingleLine: false
+AllowShortNamespacesOnASingleLine: false
+AlwaysBreakAfterDefinitionReturnType: None
+AlwaysBreakBeforeMultilineStrings: true
+AttributeMacros:
+  - __capability
+BinPackArguments: true
+BinPackParameters: BinPack
+BitFieldColonSpacing: Both
+BraceWrapping:
+  AfterCaseLabel:  false
+  AfterClass:      false
+  AfterControlStatement: Never
+  AfterEnum:       false
+  AfterExternBlock: false
+  AfterFunction:   false
+  AfterNamespace:  false
+  AfterObjCDeclaration: false
+  AfterStruct:     false
+  AfterUnion:      false
+  BeforeCatch:     false
+  BeforeElse:      false
+  BeforeLambdaBody: false
+  BeforeWhile:     false
+  IndentBraces:    false
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+BracedInitializerIndentWidth: 2
+BreakAdjacentStringLiterals: true
+BreakAfterAttributes: Leave
+BreakAfterJavaFieldAnnotations: false
+BreakAfterReturnType: None
+BreakArrays:     true
+BreakBeforeBinaryOperators: None
+BreakBeforeConceptDeclarations: Always
+BreakBeforeBraces: Attach
+BreakBeforeInlineASMColon: OnlyMultiline
+BreakBeforeTernaryOperators: true
+BreakBinaryOperations: Never
+BreakConstructorInitializers: BeforeColon
+BreakFunctionDefinitionParameters: false
+BreakInheritanceList: BeforeColon
+BreakStringLiterals: true
+BreakTemplateDeclarations: Yes
+ColumnLimit:     80
+CommentPragmas:  '^ IWYU pragma:'
+CompactNamespaces: false
+ConstructorInitializerIndentWidth: 4
+ContinuationIndentWidth: 4
+Cpp11BracedListStyle: true
+DerivePointerAlignment: true
+DisableFormat:   false
+EmptyLineAfterAccessModifier: Never
+EmptyLineBeforeAccessModifier: LogicalBlock
+ExperimentalAutoDetectBinPacking: false
+FixNamespaceComments: true
+ForEachMacros:
+  - foreach
+  - Q_FOREACH
+  - BOOST_FOREACH
+IfMacros:
+  - KJ_IF_MAYBE
+IncludeBlocks:   Regroup
+IncludeCategories:
+  - Regex:           '^<.*'
+    Priority:        2
+    SortPriority:    0
+    CaseSensitive:   false
+  - Regex:           '.*'
+    Priority:        1
+    SortPriority:    0
+    CaseSensitive:   false
+IncludeIsMainRegex: '([-_](lzma|z|test|unittest))?$'
+IncludeIsMainSourceRegex: ''
+IndentAccessModifiers: false
+IndentCaseBlocks: false
+IndentCaseLabels: true
+IndentExportBlock: true
+IndentExternBlock: AfterExternBlock
+IndentGotoLabels: true
+IndentPPDirectives: AfterHash
+IndentRequiresClause: true
+IndentWidth:     2
+IndentWrappedFunctionNames: false
+InsertBraces:    false
+InsertNewlineAtEOF: false
+InsertTrailingCommas: None
+IntegerLiteralSeparator:
+  Binary:          0
+  BinaryMinDigits: 0
+  Decimal:         0
+  DecimalMinDigits: 0
+  Hex:             0
+  HexMinDigits:    0
+JavaScriptQuotes: Leave
+JavaScriptWrapImports: true
+KeepEmptyLines:
+  AtEndOfFile:     false
+  AtStartOfBlock:  false
+  AtStartOfFile:   true
+KeepFormFeed:    false
+LambdaBodyIndentation: Signature
+LineEnding:      DeriveLF
+MacroBlockBegin: ''
+MacroBlockEnd:   ''
+MainIncludeChar: Quote
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+ObjCBinPackProtocolList: Never
+ObjCBlockIndentWidth: 2
+ObjCBreakBeforeNestedBlockParam: true
+ObjCSpaceAfterProperty: false
+ObjCSpaceBeforeProtocolList: true
+PackConstructorInitializers: NextLine
+PenaltyBreakAssignment: 2
+PenaltyBreakBeforeFirstCallParameter: 1
+PenaltyBreakBeforeMemberAccess: 150
+PenaltyBreakComment: 300
+PenaltyBreakFirstLessLess: 120
+PenaltyBreakOpenParenthesis: 0
+PenaltyBreakScopeResolution: 500
+PenaltyBreakString: 1000
+PenaltyBreakTemplateDeclaration: 10
+PenaltyExcessCharacter: 1000000
+PenaltyIndentedWhitespace: 0
+PenaltyReturnTypeOnItsOwnLine: 200
+PointerAlignment: Left
+PPIndentWidth: 1
+QualifierAlignment: Leave
+RawStringFormats:
+  - Language:        Cpp
+    Delimiters:
+      - cc
+      - CC
+      - cpp
+      - Cpp
+      - CPP
+      - 'c++'
+      - 'C++'
+    CanonicalDelimiter: ''
+    BasedOnStyle:    google
+  - Language:        TextProto
+    Delimiters:
+      - pb
+      - PB
+      - proto
+      - PROTO
+    EnclosingFunctions:
+      - EqualsProto
+      - EquivToProto
+      - PARSE_PARTIAL_TEXT_PROTO
+      - PARSE_TEST_PROTO
+      - PARSE_TEXT_PROTO
+      - ParseTextOrDie
+      - ParseTextProtoOrDie
+      - ParseTestProto
+      - ParsePartialTestProto
+    CanonicalDelimiter: pb
+    BasedOnStyle:    google
+ReferenceAlignment: Pointer
+ReflowComments: IndentOnly
+RemoveBracesLLVM: false
+RemoveEmptyLinesInUnwrappedLines: false
+RemoveParentheses: Leave
+RemoveSemicolon: false
+RequiresClausePosition: OwnLine
+RequiresExpressionIndentation: OuterScope
+SeparateDefinitionBlocks: Leave
+ShortNamespaceLines: 1
+SkipMacroDefinitionBody: false
+SortIncludes:    CaseSensitive
+SortJavaStaticImport: Before
+SortUsingDeclarations: LexicographicNumeric
+SpaceAfterCStyleCast: false
+SpaceAfterLogicalNot: false
+SpaceAfterTemplateKeyword: true
+SpaceAroundPointerQualifiers: Default
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCaseColon: false
+SpaceBeforeCpp11BracedList: false
+SpaceBeforeCtorInitializerColon: true
+SpaceBeforeInheritanceColon: true
+SpaceBeforeJsonColon: false
+SpaceBeforeParens: ControlStatements
+SpaceBeforeParensOptions:
+  AfterControlStatements: true
+  AfterForeachMacros: true
+  AfterFunctionDefinitionName: false
+  AfterFunctionDeclarationName: false
+  AfterIfMacros:   true
+  AfterOverloadedOperator: false
+  AfterPlacementOperator: true
+  AfterRequiresInClause: false
+  AfterRequiresInExpression: false
+  BeforeNonEmptyParentheses: false
+SpaceBeforeRangeBasedForLoopColon: true
+SpaceBeforeSquareBrackets: false
+SpaceInEmptyBlock: false
+SpacesBeforeTrailingComments: 2
+SpacesInAngles:  Never
+SpacesInContainerLiterals: true
+SpacesInLineCommentPrefix:
+  Minimum:         1
+  Maximum:         -1
+SpacesInParens:  Never
+SpacesInParensOptions:
+  ExceptDoubleParentheses: false
+  InCStyleCasts:   false
+  InConditionalStatements: false
+  InEmptyParentheses: false
+  Other:           false
+SpacesInSquareBrackets: false
+Standard:        Auto
+StatementAttributeLikeMacros:
+  - Q_EMIT
+StatementMacros:
+  - Q_UNUSED
+  - QT_REQUIRE_VERSION
+TableGenBreakInsideDAGArg: DontBreak
+TabWidth:        8
+UseTab:          Never
+VerilogBreakBetweenInstancePorts: true
+WhitespaceSensitiveMacros:
+  - BOOST_PP_STRINGIZE
+  - CF_SWIFT_NAME
+  - NS_SWIFT_NAME
+  - PP_STRINGIZE
+  - STRINGIZE
+WrapNamespaceBodyWithEmptyLines: Leave
+...
+
diff --git a/.clang-tidy b/.clang-tidy
new file mode 100644
index 0000000..27aad9a
--- /dev/null
+++ b/.clang-tidy
@@ -0,0 +1,2 @@
+---
+Checks: 'bugprone-*,misc-*,modernize-*,performance-*,portability-*,readability-*,-bugprone-easily-swappable-parameters,-bugprone-unchecked-optional-access,-misc-non-private-member-variables-in-classes,-misc-const-correctness,-misc-no-recursion,-modernize-avoid-c-arrays,-modernize-use-trailing-return-type,-readability-magic-numbers,-readability-identifier-length,-readability-braces-around-statements,-readability-function-cognitive-complexity,-readability-redundant-inline-specifier,-readability-implicit-bool-conversion,-readability-qualified-auto,-misc-header-include-cycle'
diff --git a/.dir-locals.el b/.dir-locals.el
new file mode 100644
index 0000000..36206e4
--- /dev/null
+++ b/.dir-locals.el
@@ -0,0 +1,13 @@
+;;; Directory Local Variables         -*- no-byte-compile: t; -*-
+;;; For more information see (info "(emacs) Directory Variables")
+
+((c++-mode . ((eval
+               .
+               (let ((project-path
+                      (locate-dominating-file default-directory ".dir-locals.el")))
+                 (setq-local flycheck-clangcheck-build-path
+                             (concat project-path "build"))
+                 (setq-local flycheck-clang-language-standard "c++23")
+                 (setq-local flycheck-clang-definitions '("HAVE_CONFIG_H"))
+                 (setq-local flycheck-clang-include-path '("../src" "../build"
+"/usr/include/librsvg-2.0" "/usr/include/gdk-pixbuf-2.0" "/usr/include/glycin-2" "/usr/include/cairo" "/usr/include/libxml2" "/usr/include/pango-1.0" "/usr/include/libmount" "/usr/include/blkid" "/usr/include/fribidi" "/usr/include/pixman-1" "/usr/include/harfbuzz" "/usr/include/freetype2" "/usr/include/libpng16" "/usr/include/glib-2.0" "/usr/lib/glib-2.0/include" "/usr/include/sysprof-6")))))))
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..567609b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+build/
diff --git a/meson.build b/meson.build
new file mode 100644
index 0000000..7edf83c
--- /dev/null
+++ b/meson.build
@@ -0,0 +1,373 @@
+project(
+  'sawmill',
+  'cpp',
+  'c',
+  version : '0.10',
+  meson_version : '>= 1.3.0',
+  default_options : [
+    'warning_level=3',
+    'cpp_std=c++26',
+    'cpp_eh=none',
+    'cpp_rtti=false',
+    'default_library=static',
+  ],
+)
+
+c_flags = []
+c_optional_flags = []
+cpp_flags = []
+if get_option('buildtype') == 'release'
+  # If asserts are disabled parameters and variables used for only that
+  # end up causing warnings
+  c_optional_flags += ['-Wno-unused-parameter', '-Wno-unused-variable',
+                       '-Wno-unused-but-set-variable']
+  c_flags += '-DNDEBUG'
+  cpp_flags += '-DNDEBUG'
+endif
+cpp = meson.get_compiler('cpp')
+foreach flag : c_optional_flags
+  if cpp.has_argument(flag)
+    cpp_flags += flag
+  endif
+endforeach
+c = meson.get_compiler('c')
+foreach flag : c_optional_flags
+  if c.has_argument(flag)
+    c_flags += flag
+  endif
+endforeach
+add_project_arguments([cpp_flags], language: 'cpp')
+add_project_arguments([c_flags], language: 'c')
+
+jpeg = dependency('libjpeg', version: '>= 2.1.5', required: false)
+png = dependency('libpng', version: '>= 1.6.0', required: true)
+rsvg = dependency('librsvg-2.0', version: '>= 2.61.0', required: false)
+xpm = dependency('xpm', version: '>= 3.5.0', required: false)
+
+image_deps = [png]
+
+if jpeg.found()
+  image_deps += jpeg
+endif
+
+if rsvg.found()
+  image_deps += rsvg
+endif
+
+if xpm.found()
+  image_deps += xpm
+endif
+
+conf_data = configuration_data()
+conf_data.set('version', meson.project_version())
+conf_data.set10('have_jpeg', jpeg.found())
+conf_data.set10('have_png', png.found())
+conf_data.set10('have_rsvg', rsvg.found())
+conf_data.set10('have_xpm', xpm.found())
+configure_file(input: 'src/config.h.in',
+               output: 'config.h',
+               configuration : conf_data)
+
+inc = include_directories('src')
+
+args_lib = library(
+  'args',
+  sources: [
+    'src/args.cc',
+    'src/args.hh',
+  ],
+  include_directories: inc,
+)
+args_dep = declare_dependency(link_with: args_lib)
+
+io_lib = library(
+  'io',
+  sources: [
+    'src/check.hh',
+    'src/line.cc',
+    'src/line.hh',
+    'src/io.cc',
+    'src/io.hh',
+    'src/unique_fd.cc',
+    'src/unique_fd.hh',
+  ],
+  include_directories: inc,
+)
+io_dep = declare_dependency(link_with: io_lib)
+
+str_lib = library(
+  'str',
+  sources: [
+    'src/str.cc',
+    'src/str.hh',
+  ],
+  include_directories: inc,
+)
+str_dep = declare_dependency(link_with: str_lib)
+
+paths_lib = library(
+  'paths',
+  sources: [
+    'src/paths.cc',
+    'src/paths.hh',
+  ],
+  include_directories: inc,
+  dependencies: [str_dep],
+)
+paths_dep = declare_dependency(
+  link_with: paths_lib,
+  dependencies: [str_dep],
+)
+
+cfg_lib = library(
+  'cfg',
+  sources: [
+    'src/cfg.cc',
+    'src/cfg.hh',
+  ],
+  include_directories: inc,
+  dependencies: [io_dep, paths_dep, str_dep],
+)
+cfg_dep = declare_dependency(
+  link_with: cfg_lib,
+  dependencies: [io_dep, paths_dep, str_dep],
+)
+
+logger_lib = library(
+  'logger',
+  sources: [
+    'src/logger.cc',
+    'src/logger.hh',
+  ],
+  include_directories: inc,
+)
+logger_dep = declare_dependency(link_with: logger_lib)
+
+if xpm.found()
+  xpm_color_inc = include_directories('src/xpm')
+  xpm_color_lib = library(
+    'xpm_color',
+    sources: [
+      'src/xpm/dix-config.h',
+      'src/xpm/dix/dix_priv.h',
+      'src/xpm/include/dix.h',
+      'src/xpm/color.c',
+    ],
+    c_args: ['-Wno-sign-compare', '-Wno-unused-parameter'],
+    include_directories: xpm_color_inc,
+    dependencies: [xpm],
+  )
+  xpm_color_dep = declare_dependency(
+    link_with: xpm_color_lib,
+    dependencies: [xpm],
+  )
+
+  image_deps += xpm_color_dep
+endif
+
+image_processor_lib = library(
+  'image_processor',
+  sources: [
+    'src/colour.cc',
+    'src/colour.hh',
+    'src/image.cc',
+    'src/image.hh',
+    'src/image_processor.cc',
+    'src/image_processor.hh',
+    'src/size.hh',
+  ],
+  include_directories: inc,
+  dependencies : image_deps,
+)
+image_processor_dep = declare_dependency(
+  link_with: image_processor_lib,
+  dependencies: image_deps,
+)
+
+spawner_lib = library(
+  'spawner',
+  sources: [
+    'src/spawner.cc',
+    'src/spawner.hh',
+  ],
+  include_directories: inc,
+  dependencies : [
+    io_dep,
+  ],
+)
+spawner_dep = declare_dependency(
+  link_with: spawner_lib,
+  dependencies: [
+    io_dep,
+  ],
+)
+
+sawmill = executable(
+  'sawmill',
+  sources: [
+    'src/main.cc',
+  ],
+  include_directories: inc,
+  install : true,
+  dependencies : [
+    args_dep,
+    cfg_dep,
+    image_processor_dep,
+    spawner_dep,
+  ],
+)
+
+gtest_main_dep = dependency('gtest_main', fallback : ['gtest', 'gtest_main_dep'])
+gmock_dep = dependency('gmock', fallback : ['gtest', 'gmock_dep'])
+
+test_dependencies = [
+  gtest_main_dep,
+]
+
+test('args', executable(
+  'test_args',
+  sources: ['test/args.cc'],
+  include_directories: inc,
+  dependencies: [
+    args_dep,
+    test_dependencies,
+  ],
+))
+
+io_test_helper_lib = library(
+  'io_test_helper',
+  sources: [
+    'test/io_test_helper.cc',
+    'test/io_test_helper.hh',
+  ],
+  include_directories: inc,
+  dependencies: io_dep,
+)
+io_test_helper_dep = declare_dependency(
+  link_with: io_test_helper_lib,
+  dependencies: io_dep,
+)
+
+testdir_lib = library(
+  'testdir',
+  sources: [
+    'test/testdir.cc',
+    'test/testdir.hh',
+  ],
+  include_directories: inc,
+  dependencies: test_dependencies,
+)
+testdir_dep = declare_dependency(
+  link_with: testdir_lib,
+  dependencies: test_dependencies,
+)
+
+testenv_lib = library(
+  'testenv',
+  sources: [
+    'test/testenv.cc',
+    'test/testenv.hh',
+  ],
+  include_directories: inc,
+  dependencies: test_dependencies,
+)
+testenv_dep = declare_dependency(
+  link_with: testenv_lib,
+  dependencies: test_dependencies,
+)
+
+test('line', executable(
+  'test_line',
+  sources: ['test/line.cc'],
+  include_directories: inc,
+  dependencies: [
+    io_dep,
+    io_test_helper_dep,
+    test_dependencies,
+  ],
+))
+
+test('str', executable(
+  'test_str',
+  sources: ['test/str.cc'],
+  include_directories: inc,
+  dependencies: [
+    str_dep,
+    test_dependencies,
+  ],
+))
+
+test('io', executable(
+  'test_io',
+  sources: ['test/io.cc'],
+  include_directories: inc,
+  dependencies: [
+    io_dep,
+    io_test_helper_dep,
+    test_dependencies,
+  ],
+))
+
+test('paths', executable(
+  'test_paths',
+  sources: ['test/paths.cc'],
+  include_directories: inc,
+  dependencies : [
+    paths_dep,
+    test_dependencies,
+    testenv_dep,
+  ],
+))
+
+test('cfg', executable(
+  'test_cfg',
+  sources: ['test/cfg.cc'],
+  include_directories: inc,
+  dependencies : [
+    cfg_dep,
+    test_dependencies,
+    testdir_dep,
+    testenv_dep,
+  ],
+))
+
+test('u8', executable(
+  'test_u8',
+  sources: [
+    'src/u.hh',
+    'src/u8.hh',
+    'test/u8.cc',
+  ],
+  include_directories: inc,
+  dependencies : [
+    test_dependencies,
+  ],
+))
+
+test('image_processor', executable(
+  'test_image_processor',
+  sources: ['test/image_processor.cc'],
+  cpp_args: ['-DTESTDIR="@0@/test/data"'.format(meson.current_source_dir())],
+  include_directories: inc,
+  dependencies : [
+    gmock_dep,
+    image_processor_dep,
+    spawner_dep,
+    test_dependencies,
+  ],
+))
+
+run_clang_tidy = find_program('run-clang-tidy', required: false)
+
+if run_clang_tidy.found()
+  # The clang-tidy target generated by meson misses most of the
+  # source files, so create our own.
+  run_target(
+    'clang-tidy',
+    command: [
+      run_clang_tidy,
+      '-quiet',
+      '-use-color',
+    ],
+  )
+endif
diff --git a/src/args.cc b/src/args.cc
new file mode 100644
index 0000000..1794941
--- /dev/null
+++ b/src/args.cc
@@ -0,0 +1,389 @@
+#include "args.hh"
+
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <format>
+#include <iostream>
+#include <map>
+#include <memory>
+#include <optional>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+namespace {
+
+std::string kEmpty;
+
+class OptionImpl : public Args::OptionArgument {
+ public:
+  enum Type : uint8_t {
+    NoArgument,
+    RequiredArgument,
+    OptionalArgument,
+  };
+
+  OptionImpl(Type type, char shortname, std::string longname, std::string arg,
+             std::string help)
+      : type(type),
+        shortname(shortname),
+        longname(std::move(longname)),
+        arg(std::move(arg)),
+        help(std::move(help)) {}
+
+  const Type type;
+  const char shortname;
+  const std::string longname;
+  const std::string arg;
+  const std::string help;
+
+  [[nodiscard]] bool is_set() const override { return is_set_; }
+
+  [[nodiscard]] bool has_argument() const override {
+    return value_.has_value();
+  }
+
+  [[nodiscard]] const std::string& argument() const override {
+    if (value_.has_value())
+      return value_.value();
+    assert(false);
+    return kEmpty;
+  }
+
+  void clear() {
+    is_set_ = false;
+    value_.reset();
+  }
+
+  void set_argument(std::string value) {
+    assert(type == Type::RequiredArgument || type == Type::OptionalArgument);
+    is_set_ = true;
+    value_ = std::move(value);
+  }
+
+  void set_no_argument() {
+    assert(type == Type::NoArgument || type == Type::OptionalArgument);
+    is_set_ = true;
+    value_.reset();
+  }
+
+ private:
+  bool is_set_{false};
+  std::optional<std::string> value_;
+};
+
+class ArgsImpl : public Args {
+ public:
+  explicit ArgsImpl(std::string prgname) : prgname_(std::move(prgname)) {}
+
+  std::shared_ptr<Option> option(char shortname, std::string longname,
+                                 std::string help) override {
+    auto opt = std::make_shared<OptionImpl>(
+        OptionImpl::Type::NoArgument, shortname, std::move(longname),
+        /* arg */ std::string(), std::move(help));
+    add(opt);
+    return opt;
+  }
+
+  std::shared_ptr<OptionArgument> option_argument(char shortname,
+                                                  std::string longname,
+                                                  std::string arg,
+                                                  std::string help,
+                                                  bool required) override {
+    auto opt = std::make_shared<OptionImpl>(
+        required ? OptionImpl::Type::RequiredArgument
+                 : OptionImpl::Type::OptionalArgument,
+        shortname, std::move(longname), std::move(arg), std::move(help));
+    add(opt);
+    return opt;
+  }
+
+  bool run(int argc, char** argv,
+           std::vector<std::string_view>* arguments = nullptr) override {
+    last_error_.clear();
+    for (auto& opt : options_) {
+      opt->clear();
+    }
+
+    std::string_view prgname;
+    if (prgname_.empty()) {
+      if (argc > 0)
+        prgname = argv[0];
+    } else {
+      prgname = prgname_;
+    }
+
+    for (int a = 1; a < argc; ++a) {
+      assert(argv[a]);
+      if (argv[a][0] == '-' && argv[a][1] != '\0') {
+        if (argv[a][1] == '-') {
+          // long option
+          size_t eq = 2;
+          while (argv[a][eq] != '=' && argv[a][eq] != '\0')
+            ++eq;
+          size_t end = eq;
+          while (argv[a][end] != '\0')
+            ++end;
+
+          if (end == 2) {
+            // "--", no more options signal
+            if (arguments) {
+              for (++a; a < argc; ++a)
+                arguments->emplace_back(argv[a]);
+            }
+            break;
+          }
+
+          auto name = std::string_view(argv[a] + 2, eq - 2);
+          auto it = long_.find(name);
+          if (it == long_.end()) {
+            last_error_ =
+                std::format("{}: unrecognized option '--{}'", prgname, name);
+            return false;
+          }
+          auto& opt = options_[it->second];
+
+          if (eq < end) {
+            // long option with argument after equal sign
+            switch (opt->type) {
+              case OptionImpl::Type::NoArgument:
+                last_error_ =
+                    std::format("{}: option '--{}' doesn't allow an argument",
+                                prgname, name);
+                return false;
+              case OptionImpl::Type::RequiredArgument:
+              case OptionImpl::Type::OptionalArgument:
+                opt->set_argument(
+                    std::string(argv[a] + eq + 1, end - (eq + 1)));
+                break;
+            }
+          } else {
+            switch (opt->type) {
+              case OptionImpl::Type::NoArgument:
+              case OptionImpl::Type::OptionalArgument:
+                opt->set_no_argument();
+                break;
+              case OptionImpl::Type::RequiredArgument:
+                if (++a >= argc) {
+                  last_error_ = std::format(
+                      "{}: option '--{}' requires an argument", prgname, name);
+                  return false;
+                }
+                opt->set_argument(argv[a]);
+                break;
+            }
+          }
+        } else {
+          // short options
+          char* current = argv[a] + 1;
+          for (; *current; ++current) {
+            auto it = short_.find(*current);
+            if (it == short_.end()) {
+              last_error_ =
+                  std::format("{}: invalid option -- '{}'", prgname, *current);
+              return false;
+            }
+
+            auto& opt = options_[it->second];
+            switch (opt->type) {
+              case OptionImpl::Type::NoArgument:
+              case OptionImpl::Type::OptionalArgument:
+                opt->set_no_argument();
+                break;
+              case OptionImpl::Type::RequiredArgument:
+                if (++a >= argc) {
+                  last_error_ =
+                      std::format("{}: option requires an argument -- '{}'",
+                                  prgname, *current);
+                  return false;
+                }
+                opt->set_argument(argv[a]);
+                break;
+            }
+          }
+        }
+      } else {
+        if (arguments)
+          arguments->emplace_back(argv[a]);
+      }
+    }
+    return true;
+  }
+
+  void print_error(std::ostream& out) const override {
+    if (last_error_.empty())
+      return;
+
+    out << last_error_ << '\n';
+  }
+
+  void print_help(std::ostream& out, uint32_t width = 79) const override {
+    if (options_.empty())
+      return;
+
+    uint32_t indent = 0;
+    const uint32_t max_need = width / 2;
+    std::vector<uint32_t> option_need;
+    for (auto const& opt : options_) {
+      uint32_t need;
+      if (opt->longname.empty()) {
+        need = 4;  // -O
+        switch (opt->type) {
+          case OptionImpl::Type::NoArgument:
+          case OptionImpl::Type::OptionalArgument:
+            break;
+          case OptionImpl::Type::RequiredArgument:
+            need += 1 + (opt->arg.empty() ? 3 : opt->arg.size());
+            break;
+        }
+      } else {
+        need = 8 + opt->longname.size();  // -O, --option
+        switch (opt->type) {
+          case OptionImpl::Type::NoArgument:
+            break;
+          case OptionImpl::Type::RequiredArgument:
+            // =ARG
+            need += 1 + (opt->arg.empty() ? 3 : opt->arg.size());
+            break;
+          case OptionImpl::Type::OptionalArgument:
+            // [=ARG]
+            need += 3 + (opt->arg.empty() ? 3 : opt->arg.size());
+            break;
+        }
+      }
+      need += 2;  // margin
+
+      option_need.emplace_back(need);
+      if (need <= max_need) {
+        indent = std::max(indent, need);
+      }
+    }
+
+    print_wrap(out, width, /* indent */ 0,
+               "Mandatory arguments to long options"
+               " are mandatory for short options too.");
+    auto need_it = option_need.begin();
+    for (auto const& opt : options_) {
+      if (opt->longname.empty()) {
+        out << "  -" << opt->shortname;
+        switch (opt->type) {
+          case OptionImpl::Type::NoArgument:
+          case OptionImpl::Type::OptionalArgument:
+            break;
+          case OptionImpl::Type::RequiredArgument:
+            out << " " << (opt->arg.empty() ? "ARG" : opt->arg);
+            break;
+        }
+      } else {
+        if (opt->shortname != '\0') {
+          out << "  -" << opt->shortname << ", --";
+        } else {
+          out << "      --";
+        }
+        out << opt->longname;
+        switch (opt->type) {
+          case OptionImpl::Type::NoArgument:
+            break;
+          case OptionImpl::Type::RequiredArgument:
+            out << "=" << (opt->arg.empty() ? "ARG" : opt->arg);
+            break;
+          case OptionImpl::Type::OptionalArgument:
+            out << "=[" << (opt->arg.empty() ? "ARG" : opt->arg) << ']';
+            break;
+        }
+      }
+
+      auto need = *need_it++;
+      if (need > max_need) {
+        out << '\n';
+        if (!opt->help.empty()) {
+          print_wrap(out, width, 0, opt->help);
+        }
+      } else {
+        if (opt->help.empty()) {
+          out << '\n';
+        } else {
+          out << "  ";  // add margin, already included in need
+          while (need++ < indent)
+            out << ' ';
+          print_wrap(out, width, indent, opt->help);
+        }
+      }
+    }
+  }
+
+ private:
+  void add(std::shared_ptr<OptionImpl> opt) {
+    if (opt->shortname == '\0' && opt->longname.empty()) {
+      assert(false);
+    } else {
+      auto idx = options_.size();
+      if (opt->shortname != '\0')
+        short_.emplace(opt->shortname, idx);
+      if (!opt->longname.empty())
+        long_.emplace(opt->longname, idx);
+    }
+    options_.emplace_back(std::move(opt));
+  }
+
+  static inline bool is_whitespace(char c) { return c == ' ' || c == '\t'; }
+
+  static void print_wrap(std::ostream& out, uint32_t width, uint32_t indent,
+                         const std::string& str) {
+    if (indent + str.size() <= width) {
+      out << str << '\n';
+      return;
+    }
+    if (width <= indent || indent + 10 > width) {
+      out << '\n';
+      out << str << '\n';
+      return;
+    }
+    const std::string indent_str(indent, ' ');
+    const uint32_t avail = width - indent;
+    size_t offset = 0;
+    while (offset + avail < str.size()) {
+      uint32_t i = avail;
+      while (i > 0 && !is_whitespace(str[offset + i]))
+        --i;
+      if (i == 0) {
+        out << str.substr(offset, avail - 1);
+        out << "-\n";
+        offset += avail - 1;
+      } else {
+        out << str.substr(offset, i);
+        out << '\n';
+        offset += i;
+      }
+      out << indent_str;
+    }
+    out << str.substr(offset);
+    out << '\n';
+  }
+
+  const std::string prgname_;
+  std::vector<std::shared_ptr<OptionImpl>> options_;
+  std::map<char, size_t> short_;
+  std::map<std::string_view, size_t> long_;
+  std::string last_error_;
+};
+
+}  // namespace
+
+std::shared_ptr<Args::Option> Args::option(std::string longname,
+                                           std::string help) {
+  return option(/* shortname */ '\0', std::move(longname), std::move(help));
+}
+
+std::shared_ptr<Args::OptionArgument> Args::option_argument(
+    std::string longname, std::string arg, std::string help, bool required) {
+  return option_argument(/* shortname */ '\0', std::move(longname),
+                         std::move(arg), std::move(help), required);
+}
+
+std::unique_ptr<Args> Args::create(std::string prgname) {
+  return std::make_unique<ArgsImpl>(std::move(prgname));
+}
diff --git a/src/args.hh b/src/args.hh
new file mode 100644
index 0000000..14f3716
--- /dev/null
+++ b/src/args.hh
@@ -0,0 +1,64 @@
+#ifndef ARGS_HH
+#define ARGS_HH
+
+#include <cstdint>
+#include <iosfwd>
+#include <memory>
+#include <string>
+#include <string_view>
+#include <vector>
+
+class Args {
+ public:
+  virtual ~Args() = default;
+
+  class Option {
+   public:
+    virtual ~Option() = default;
+
+    [[nodiscard]] virtual bool is_set() const = 0;
+
+   protected:
+    Option() = default;
+    Option(Option const&) = delete;
+    Option& operator=(Option const&) = delete;
+  };
+
+  class OptionArgument : public Option {
+   public:
+    [[nodiscard]] virtual bool has_argument() const = 0;
+    [[nodiscard]] virtual const std::string& argument() const = 0;
+  };
+
+  static std::unique_ptr<Args> create(std::string prgname = std::string());
+
+  virtual std::shared_ptr<Option> option(char shortname,
+                                         std::string longname = std::string(),
+                                         std::string help = std::string()) = 0;
+
+  std::shared_ptr<Option> option(std::string longname,
+                                 std::string help = std::string());
+
+  virtual std::shared_ptr<OptionArgument> option_argument(
+      char shortname, std::string longname = std::string(),
+      std::string arg = std::string(), std::string help = std::string(),
+      bool required = true) = 0;
+
+  std::shared_ptr<OptionArgument> option_argument(
+      std::string longname, std::string arg = std::string(),
+      std::string help = std::string(), bool required = true);
+
+  virtual bool run(int argc, char** argv,
+                   std::vector<std::string_view>* arguments = nullptr) = 0;
+
+  virtual void print_error(std::ostream& out) const = 0;
+
+  virtual void print_help(std::ostream& out, uint32_t width = 79) const = 0;
+
+ protected:
+  Args() = default;
+  Args(Args const&) = delete;
+  Args& operator=(Args const&) = delete;
+};
+
+#endif  // ARGS_HH
diff --git a/src/cfg.cc b/src/cfg.cc
new file mode 100644
index 0000000..b65246f
--- /dev/null
+++ b/src/cfg.cc
@@ -0,0 +1,199 @@
+#include "cfg.hh"
+
+#include "io.hh"
+#include "line.hh"
+#include "paths.hh"
+#include "str.hh"
+
+#include <charconv>
+#include <cstdint>
+#include <format>
+#include <functional>
+#include <map>
+#include <memory>
+#include <optional>
+#include <string>
+#include <string_view>
+#include <system_error>
+#include <utility>
+#include <vector>
+
+namespace cfg {
+
+namespace {
+
+inline char ascii_lowercase(char c) {
+  if (c >= 'A' && c <= 'Z') {
+    // NOLINTNEXTLINE(bugprone-narrowing-conversions)
+    return c | 0x20;
+  }
+  return c;
+}
+
+bool ascii_lowercase_eq(std::string_view a, std::string_view b) {
+  if (a.size() != b.size())
+    return false;
+  auto it_a = a.begin();
+  auto it_b = b.begin();
+  for (; it_a != a.end(); ++it_a, ++it_b) {
+    if (ascii_lowercase(*it_a) != *it_b)
+      return false;
+  }
+  return true;
+}
+
+class ConfigSingleImpl : public Config {
+ public:
+  ConfigSingleImpl() = default;
+
+  bool load(std::filesystem::path const& path,
+            std::vector<std::string>& errors) {
+    auto io_reader = io::open(std::string(path));
+    if (!io_reader.has_value()) {
+      errors.push_back(
+          std::format("Unable to open {} for reading", path.string()));
+      return false;
+    }
+    bool all_ok = true;
+    auto line_reader = line::open(std::move(io_reader.value()));
+    while (true) {
+      auto line = line_reader->read();
+      if (line.has_value()) {
+        auto trimmed = str::trim(line.value());
+        if (trimmed.empty() || trimmed.front() == '#')
+          continue;
+        auto eq = trimmed.find('=');
+        if (eq == std::string_view::npos) {
+          errors.push_back(
+              std::format("{}:{}: Invalid line, expected key = value.",
+                          path.string(), line_reader->number()));
+          all_ok = false;
+          continue;
+        }
+        auto key = str::trim(trimmed.substr(0, eq));
+        auto value = str::trim(trimmed.substr(eq + 1));
+        auto ret = values_.emplace(key, value);
+        if (!ret.second) {
+          errors.push_back(std::format("{}:{}: Duplicate key {} ignored.",
+                                       path.string(), line_reader->number(),
+                                       key));
+          all_ok = false;
+          continue;
+        }
+      } else {
+        switch (line.error()) {
+          case io::ReadError::Eof:
+            break;
+          default:
+            errors.push_back(std::format("{}: Read error", path.string()));
+            all_ok = false;
+            break;
+        }
+        break;
+      }
+    }
+    return all_ok;
+  }
+
+  [[nodiscard]]
+  std::optional<std::string_view> get(std::string_view name) const override {
+    auto it = values_.find(name);
+    if (it == values_.end())
+      return std::nullopt;
+    return it->second;
+  }
+
+ private:
+  std::map<std::string, std::string, std::less<>> values_;
+};
+
+class ConfigXdgImpl : public Config {
+ public:
+  ConfigXdgImpl() = default;
+
+  bool load(std::string_view name, std::vector<std::string>& errors) {
+    bool all_ok = true;
+    for (auto const& dir : paths::config_dirs()) {
+      auto file = dir / name;
+      if (std::filesystem::exists(file)) {
+        auto cfg = std::make_unique<ConfigSingleImpl>();
+        if (!cfg->load(file, errors))
+          all_ok = false;
+        configs_.push_back(std::move(cfg));
+      }
+    }
+    return all_ok;
+  }
+
+  [[nodiscard]]
+  std::optional<std::string_view> get(std::string_view name) const override {
+    for (auto const& config : configs_) {
+      auto ret = config->get(name);
+      if (ret.has_value())
+        return ret;
+    }
+    return std::nullopt;
+  }
+
+ private:
+  std::vector<std::unique_ptr<ConfigSingleImpl>> configs_;
+};
+
+}  // namespace
+
+bool Config::has(std::string_view name) const { return get(name).has_value(); }
+
+std::optional<int64_t> Config::get_int64(std::string_view name) const {
+  auto str = get(name);
+  if (str.has_value()) {
+    auto* const end = str->data() + str->size();
+    int64_t ret;
+    // NOLINTNEXTLINE(bugprone-suspicious-stringview-data-usage)
+    auto [ptr, ec] = std::from_chars(str->data(), end, ret);
+    if (ec == std::errc() && ptr == end)
+      return ret;
+  }
+  return std::nullopt;
+}
+
+std::optional<uint64_t> Config::get_uint64(std::string_view name) const {
+  auto str = get(name);
+  if (str.has_value()) {
+    auto* const end = str->data() + str->size();
+    uint64_t ret;
+    // NOLINTNEXTLINE(bugprone-suspicious-stringview-data-usage)
+    auto [ptr, ec] = std::from_chars(str->data(), end, ret);
+    if (ec == std::errc() && ptr == end)
+      return ret;
+  }
+  return std::nullopt;
+}
+
+std::optional<bool> Config::get_bool(std::string_view name) const {
+  auto str = get(name);
+  if (str.has_value()) {
+    if (ascii_lowercase_eq(str.value(), "true") ||
+        ascii_lowercase_eq(str.value(), "yes"))
+      return true;
+    if (ascii_lowercase_eq(str.value(), "false") ||
+        ascii_lowercase_eq(str.value(), "no"))
+      return false;
+  }
+  return std::nullopt;
+}
+
+std::unique_ptr<Config> load_all(std::string_view name,
+                                 std::vector<std::string>& errors) {
+  auto ret = std::make_unique<ConfigXdgImpl>();
+  ret->load(name, errors);
+  return ret;
+}
+
+std::unique_ptr<Config> load_one(std::filesystem::path const& path,
+                                 std::vector<std::string>& errors) {
+  auto ret = std::make_unique<ConfigSingleImpl>();
+  ret->load(path, errors);
+  return ret;
+}
+
+}  // namespace cfg
diff --git a/src/cfg.hh b/src/cfg.hh
new file mode 100644
index 0000000..3be9a00
--- /dev/null
+++ b/src/cfg.hh
@@ -0,0 +1,45 @@
+#ifndef CFG_HH
+#define CFG_HH
+
+#include <filesystem>
+#include <memory>
+#include <optional>
+#include <string_view>
+#include <vector>
+
+namespace cfg {
+
+class Config {
+ public:
+  virtual ~Config() = default;
+
+  [[nodiscard]]
+  virtual std::optional<std::string_view> get(std::string_view name) const = 0;
+
+  [[nodiscard]]
+  bool has(std::string_view name) const;
+  [[nodiscard]]
+  std::optional<int64_t> get_int64(std::string_view name) const;
+  [[nodiscard]]
+  std::optional<uint64_t> get_uint64(std::string_view name) const;
+  [[nodiscard]]
+  std::optional<bool> get_bool(std::string_view name) const;
+
+ protected:
+  Config() = default;
+
+  Config(Config const&) = delete;
+  Config& operator=(Config const&) = delete;
+};
+
+[[nodiscard]]
+std::unique_ptr<Config> load_all(std::string_view name,
+                                 std::vector<std::string>& errors);
+
+[[nodiscard]]
+std::unique_ptr<Config> load_one(std::filesystem::path const& path,
+                                 std::vector<std::string>& errors);
+
+}  // namespace cfg
+
+#endif  // CFG_HH
diff --git a/src/check.hh b/src/check.hh
new file mode 100644
index 0000000..91c1717
--- /dev/null
+++ b/src/check.hh
@@ -0,0 +1,39 @@
+#ifndef CHECK_HH
+#define CHECK_HH
+
+#include <cstdlib>
+#include <stdckdint.h>
+#include <type_traits>
+
+namespace check {
+
+template <typename T>
+  requires std::is_arithmetic_v<T>
+T add(T a, T b) {
+  T ret;
+  if (ckd_add(&ret, a, b))
+    abort();
+  return ret;
+}
+
+template <typename T>
+  requires std::is_arithmetic_v<T>
+T sub(T a, T b) {
+  T ret;
+  if (ckd_sub(&ret, a, b))
+    abort();
+  return ret;
+}
+
+template <typename T>
+  requires std::is_arithmetic_v<T>
+T mul(T a, T b) {
+  T ret;
+  if (ckd_mul(&ret, a, b))
+    abort();
+  return ret;
+}
+
+}  // namespace check
+
+#endif  // CHECK_HH
diff --git a/src/colour.cc b/src/colour.cc
new file mode 100644
index 0000000..e9df340
--- /dev/null
+++ b/src/colour.cc
@@ -0,0 +1,15 @@
+#include "colour.hh"
+
+#include <cstdint>
+
+Colour::Colour() : argb(0) {}
+
+Colour::Colour(uint32_t argb) : argb(argb) {}
+
+Colour::Colour(uint8_t r, uint8_t g, uint8_t b)
+    : argb(0xff000000 | (static_cast<uint32_t>(r) << 16) |
+           (static_cast<uint32_t>(g) << 8) | b) {}
+
+Colour::Colour(uint8_t a, uint8_t r, uint8_t g, uint8_t b)
+    : argb((static_cast<uint32_t>(a) << 24) | (static_cast<uint32_t>(r) << 16) |
+           (static_cast<uint32_t>(g) << 8) | b) {}
diff --git a/src/colour.hh b/src/colour.hh
new file mode 100644
index 0000000..8362bb3
--- /dev/null
+++ b/src/colour.hh
@@ -0,0 +1,20 @@
+#ifndef COLOUR_HH
+#define COLOUR_HH
+
+#include <cstdint>
+
+struct Colour {
+  Colour();
+  explicit Colour(uint32_t argb);
+  Colour(uint8_t r, uint8_t g, uint8_t b);
+  Colour(uint8_t a, uint8_t r, uint8_t g, uint8_t b);
+
+  uint8_t alpha() const { return argb >> 24; };
+  uint8_t red() const { return (argb >> 16) & 0xff; };
+  uint8_t green() const { return (argb >> 8) & 0xff; };
+  uint8_t blue() const { return argb & 0xff; };
+
+  uint32_t argb;
+};
+
+#endif  // COLOUR_HH
diff --git a/src/config.h.in b/src/config.h.in
new file mode 100644
index 0000000..5280a3d
--- /dev/null
+++ b/src/config.h.in
@@ -0,0 +1,6 @@
+#define VERSION "@version@"
+
+#define HAVE_JPEG @have_jpeg@
+#define HAVE_PNG @have_png@
+#define HAVE_RSVG @have_rsvg@
+#define HAVE_XPM @have_xpm@
diff --git a/src/image.cc b/src/image.cc
new file mode 100644
index 0000000..3e3b485
--- /dev/null
+++ b/src/image.cc
@@ -0,0 +1,15 @@
+#include "image.hh"
+
+#include "size.hh"
+
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <utility>
+
+Image::Image(Format format, Size size, size_t scanline,
+             std::unique_ptr<uint8_t[]> pixels)
+    : format_(format),
+      size_(size),
+      scanline_(scanline),
+      pixels_(std::move(pixels)) {}
diff --git a/src/image.hh b/src/image.hh
new file mode 100644
index 0000000..8191393
--- /dev/null
+++ b/src/image.hh
@@ -0,0 +1,62 @@
+#ifndef IMAGE_HH
+#define IMAGE_HH
+
+#include "size.hh"
+
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+
+class Image {
+ public:
+  enum class Format : uint8_t {
+    RGBA_8888,
+    ARGB_8888,
+    BGRA_8888,
+    ABGR_8888,
+  };
+
+  [[nodiscard]]
+  Size const& size() const {
+    return size_;
+  }
+
+  [[nodiscard]]
+  uint32_t width() const {
+    return size_.width;
+  }
+
+  [[nodiscard]]
+  uint32_t height() const {
+    return size_.height;
+  }
+
+  [[nodiscard]]
+  Format format() const {
+    return format_;
+  }
+
+  [[nodiscard]]
+  size_t scanline() const {
+    return scanline_;
+  }
+
+  [[nodiscard]]
+  uint8_t const* data() const {
+    return pixels_.get();
+  }
+
+  Image(Format format, Size size, size_t scanline,
+        std::unique_ptr<uint8_t[]> pixels);
+
+ private:
+  Image(Image const&) = delete;
+  Image& operator=(Image const&) = delete;
+
+  Format const format_;
+  Size const size_;
+  size_t const scanline_;
+  std::unique_ptr<uint8_t[]> pixels_;
+};
+
+#endif  // IMAGE_HH
diff --git a/src/image_loader.hh b/src/image_loader.hh
new file mode 100644
index 0000000..d283624
--- /dev/null
+++ b/src/image_loader.hh
@@ -0,0 +1,15 @@
+#ifndef IMAGE_LOADER_HH
+#define IMAGE_LOADER_HH
+
+#include "image.hh"  // IWYU pragma: export
+
+#include <cstdint>
+
+enum class ImageLoadError : uint8_t {
+  kNoSuchFile,
+  kUnsupportedFormat,
+  kProcessError,
+  kError,
+};
+
+#endif  // IMAGE_LOADER_HH
diff --git a/src/image_processor.cc b/src/image_processor.cc
new file mode 100644
index 0000000..55e3cac
--- /dev/null
+++ b/src/image_processor.cc
@@ -0,0 +1,947 @@
+#include "image_processor.hh"
+
+#include "colour.hh"
+#include "config.h"
+#include "image.hh"
+#include "image_loader.hh"
+#include "io.hh"
+#include "size.hh"
+#include "spawner.hh"
+
+#include <algorithm>
+#include <bit>
+#include <cassert>
+#include <cctype>
+#include <charconv>
+#include <cstdint>
+#include <cstring>
+#include <expected>
+#include <filesystem>
+#include <memory>
+#include <optional>
+#include <span>
+#include <string>
+#include <system_error>
+#include <utility>
+
+#if HAVE_JPEG || HAVE_PNG
+# include <cerrno>
+# include <csetjmp>
+# include <cstddef>
+# include <cstdio>
+#endif
+
+#if HAVE_JPEG
+# include <jpeglib.h>
+#endif
+
+#if HAVE_PNG
+# include <png.h>
+#endif
+
+#if HAVE_RSVG
+# include <cairo.h>
+# include <cmath>
+# include <gio/gio.h>
+# include <glib-object.h>
+# include <librsvg/rsvg.h>
+#endif
+
+#if HAVE_XPM
+# include <X11/xpm.h>
+extern "C" {
+# include "xpm/include/dix.h"
+}
+#endif
+
+namespace {
+
+struct Request {
+  bool head;
+  Image::Format format;
+  uint32_t max_width;
+  uint32_t max_height;
+  uint32_t background;
+  size_t path_len;
+};
+
+struct Response {
+  uint32_t width;
+  uint32_t height;
+  uint8_t error;
+  size_t scanline;
+};
+
+struct Result {
+  Response response;
+  Image::Format format;
+  std::unique_ptr<uint8_t[]> pixels;
+};
+
+std::expected<void, ImageLoadError> write_request(
+    io::Writer& writer, std::filesystem::path const& path, bool head,
+    Image::Format format, uint32_t max_width, uint32_t max_height,
+    Colour background) {
+  auto path_str = path.native();
+  Request request{.head = head,       .format = format, .max_width = max_width,
+                  .max_height = max_height, .background = background.argb,
+                  .path_len = path_str.size()};
+  auto ret = writer.repeat_write(&request, sizeof(request));
+  if (!ret.has_value() || ret.value() != sizeof(request)) {
+    return std::unexpected(ImageLoadError::kProcessError);
+  }
+  ret = writer.repeat_write(path_str.data(), path_str.size());
+  if (!ret.has_value() || ret.value() != path_str.size()) {
+    return std::unexpected(ImageLoadError::kProcessError);
+  }
+  return {};
+}
+
+std::expected<Response, ImageLoadError> read_response(io::Reader& reader) {
+  Response response;
+  auto ret = reader.repeat_read(&response, sizeof(response));
+  if (!ret.has_value() || ret.value() != sizeof(response)) {
+    return std::unexpected(ImageLoadError::kProcessError);
+  }
+  if (response.width == 0) {
+    return std::unexpected(static_cast<ImageLoadError>(response.error));
+  }
+  return response;
+}
+
+Size rescale(Size const& size, uint32_t max_width, uint32_t max_height) {
+  if (max_width > 0 && size.width > max_height) {
+    if (max_height > 0 && size.height > max_height) {
+      auto sx = static_cast<float>(size.width) / static_cast<float>(max_width);
+      auto sy = static_cast<float>(size.height) / static_cast<float>(max_height);
+      if (sx >= sy) {
+        return Size{max_width, (size.height * max_width) / size.width};
+      }
+      return Size{(size.width * max_height) / size.height, max_height};
+    }
+    return Size{max_width, (size.height * max_width) / size.width};
+  }
+  if (max_height > 0 && size.height > max_height) {
+    return Size{(size.width * max_height) / size.height, max_height};
+  }
+  return size;
+}
+
+void swap_four_bytes(std::span<uint8_t> pixels, uint32_t width, uint32_t height,
+                     size_t scanline) {
+  assert(height * scanline <= pixels.size());
+  auto* row = pixels.data();
+  while (height--) {
+    auto* const pixel = reinterpret_cast<uint32_t*>(row);
+    for (uint32_t x = 0; x < width; ++x) {
+      pixel[x] = std::byteswap(pixel[x]);
+    }
+    row += scanline;
+  }
+}
+
+void swap_two_bytes(std::span<uint8_t> pixels, uint32_t width, uint32_t height,
+                    size_t scanline, size_t offset) {
+  assert(offset < 4);
+  assert(height * scanline <= pixels.size());
+  auto* row = pixels.data();
+  while (height--) {
+    auto* pixel = row + offset;
+    for (uint32_t x = 0; x < width; ++x, pixel += 4) {
+      std::swap(pixel[0], pixel[2]);
+    }
+    row += scanline;
+  }
+}
+
+void shift_left_bytes(std::span<uint8_t> pixels, uint32_t width,
+                      uint32_t height, size_t scanline) {
+  assert(height * scanline <= pixels.size());
+  auto* row = pixels.data();
+  while (height--) {
+    auto* const pixel = reinterpret_cast<uint32_t*>(row);
+    for (uint32_t x = 0; x < width; ++x) {
+      pixel[x] = std::rotl(pixel[x], 8);
+    }
+    row += scanline;
+  }
+}
+
+void shift_right_bytes(std::span<uint8_t> pixels, uint32_t width,
+                       uint32_t height, size_t scanline) {
+  assert(height * scanline <= pixels.size());
+  auto* row = pixels.data();
+  while (height--) {
+    auto* const pixel = reinterpret_cast<uint32_t*>(row);
+    for (uint32_t x = 0; x < width; ++x) {
+      pixel[x] = std::rotr(pixel[x], 8);
+    }
+    row += scanline;
+  }
+}
+
+void set_alpha_bytes(std::span<uint8_t> pixels, uint32_t width, uint32_t height,
+                     size_t scanline, size_t offset) {
+  assert(height * scanline <= pixels.size());
+  assert(offset < 4);
+  auto* row = pixels.data();
+  while (height--) {
+    auto* pixel = row + offset;
+    for (uint32_t x = 0; x < width; ++x, pixel += 4) {
+      *pixel = 0xff;
+    }
+    row += scanline;
+  }
+}
+
+void insert_alpha_bytes(std::span<uint8_t> pixels, uint32_t width,
+                        uint32_t height, size_t scanline, size_t offset) {
+  assert(static_cast<size_t>(width) * 4 <= scanline);
+  assert(height * scanline <= pixels.size());
+
+  if (offset == 0) {
+    auto* row = pixels.data();
+    while (height--) {
+      auto* read_pixel = row + static_cast<size_t>((width - 1) * 3);
+      auto* write_pixel = row + static_cast<size_t>((width - 1) * 4);
+      for (uint32_t x = 0; x < width; ++x, read_pixel -= 3, write_pixel -= 4) {
+        write_pixel[0] = 0xff;
+        std::copy_n(read_pixel, 3, write_pixel + 1);
+      }
+      row += scanline;
+    }
+  } else {
+    assert(offset == 3);
+
+    auto* row = pixels.data();
+    while (height--) {
+      auto* read_pixel = row + static_cast<size_t>((width - 1) * 3);
+      auto* write_pixel = row + static_cast<size_t>((width - 1) * 4);
+      for (uint32_t x = 0; x < width; ++x, read_pixel -= 3, write_pixel -= 4) {
+        std::copy_n(read_pixel, 3, write_pixel);
+        write_pixel[3] = 0xff;
+      }
+      row += scanline;
+    }
+  }
+}
+
+void rearrange_bytes(std::span<uint8_t> pixels, uint32_t width, uint32_t height,
+                     size_t scanline, Image::Format source,
+                     Image::Format target) {
+  switch (source) {
+    case Image::Format::RGBA_8888:
+      switch (target) {
+        case Image::Format::RGBA_8888:
+          return;
+        case Image::Format::ARGB_8888:
+          shift_right_bytes(pixels, width, height, scanline);
+          return;
+        case Image::Format::BGRA_8888:
+          swap_two_bytes(pixels, width, height, scanline, 0);
+          return;
+        case Image::Format::ABGR_8888:
+          swap_four_bytes(pixels, width, height, scanline);
+          return;
+      }
+      break;
+    case Image::Format::ARGB_8888:
+      switch (target) {
+        case Image::Format::RGBA_8888:
+          shift_left_bytes(pixels, width, height, scanline);
+          return;
+        case Image::Format::ARGB_8888:
+          return;
+        case Image::Format::BGRA_8888:
+          swap_four_bytes(pixels, width, height, scanline);
+          return;
+        case Image::Format::ABGR_8888:
+          swap_two_bytes(pixels, width, height, scanline, 1);
+          return;
+      }
+      break;
+    case Image::Format::BGRA_8888:
+      switch (target) {
+        case Image::Format::RGBA_8888:
+          swap_two_bytes(pixels, width, height, scanline, 0);
+          return;
+        case Image::Format::ARGB_8888:
+          swap_four_bytes(pixels, width, height, scanline);
+          return;
+        case Image::Format::BGRA_8888:
+          return;
+        case Image::Format::ABGR_8888:
+          shift_left_bytes(pixels, width, height, scanline);
+          return;
+      }
+      break;
+    case Image::Format::ABGR_8888:
+      switch (target) {
+        case Image::Format::RGBA_8888:
+          swap_four_bytes(pixels, width, height, scanline);
+          return;
+        case Image::Format::ARGB_8888:
+          swap_two_bytes(pixels, width, height, scanline, 1);
+          return;
+        case Image::Format::BGRA_8888:
+          shift_right_bytes(pixels, width, height, scanline);
+          return;
+        case Image::Format::ABGR_8888:
+          return;
+      }
+      break;
+  }
+}
+
+#if HAVE_JPEG
+struct jpeg_extended_error_mgr {
+  struct jpeg_error_mgr err;
+  jmp_buf jmpbuf;
+};
+
+void jpeg_error_exit(j_common_ptr info) {
+  auto* err = reinterpret_cast<jpeg_extended_error_mgr*>(info->err);
+  jpeg_destroy(info);
+  longjmp(err->jmpbuf, 1);
+}
+
+void jpeg_error_output_nothing(j_common_ptr /* info */) {
+  // be silent, do nothing
+}
+
+# if BITS_IN_JSAMPLE != 8
+#  error Unsupported libjpeg setup
+# endif
+
+std::expected<Result, ImageLoadError> load_jpeg(
+    std::filesystem::path const& path, Request const& request) {
+  jpeg_extended_error_mgr err;
+  FILE* fh = nullptr;
+  if (setjmp(err.jmpbuf)) {
+    // This is better than exit() which is the default behavior,
+    // but almost guaranteed to leak some memory here.
+    if (fh)
+      fclose(fh);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  fh = fopen(path.c_str(), "rb");
+  if (fh == nullptr) {
+    if (errno == ENOENT) {
+      return std::unexpected(ImageLoadError::kNoSuchFile);
+    }
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  jpeg_decompress_struct info;
+  info.err = jpeg_std_error(&err.err);
+  info.err->error_exit = jpeg_error_exit;
+  info.err->output_message = jpeg_error_output_nothing;
+
+  jpeg_create_decompress(&info);
+
+  jpeg_stdio_src(&info, fh);
+  if (jpeg_read_header(&info, TRUE) != JPEG_HEADER_OK) {
+    jpeg_destroy_decompress(&info);
+    fclose(fh);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  if (request.head) {
+    Response resp{.width = info.image_width, .height = info.image_height, .error = 0, .scanline = 0};
+    jpeg_destroy_decompress(&info);
+    fclose(fh);
+    return Result{.response=resp, .format=Image::Format::RGBA_8888, .pixels=nullptr};
+  }
+
+  enum class Conversion : uint8_t {
+    kNone,
+    kSetAlphaFirst,
+    kSetAlphaLast,
+    kAddAlphaFirst,
+    kAddAlphaLast,
+  } conversion = Conversion::kNone;
+  Image::Format output_format = request.format;
+
+# if JCS_EXTENSIONS
+#  if JCS_ALPHA_EXTENSIONS
+  switch (request.format) {
+    case Image::Format::RGBA_8888:
+      info.out_color_space = JCS_EXT_RGBA;
+      break;
+    case Image::Format::BGRA_8888:
+      info.out_color_space = JCS_EXT_BGRA;
+      break;
+    case Image::Format::ABGR_8888:
+      info.out_color_space = JCS_EXT_ABGR;
+      break;
+    case Image::Format::ARGB_8888:
+      info.out_color_space = JCS_EXT_ARGB;
+      break;
+  }
+#  else
+  switch (request.format) {
+    case Image::Format::RGBA_8888:
+      info.out_color_space = JCS_EXT_RGBX;
+      conversion = Conversion::kSetAlphaLast;
+      break;
+    case Image::Format::BGRA_8888:
+      info.out_color_space = JCS_EXT_BGRX;
+      conversion = Conversion::kSetAlphaLast;
+      break;
+    case Image::Format::ABGR_8888:
+      info.out_color_space = JCS_EXT_XBGR;
+      conversion = Conversion::kSetAlphaFirst;
+      break;
+    case Image::Format::ARGB_8888:
+      info.out_color_space = JCS_EXT_XRGB;
+      conversion = Conversion::kSetAlphaFirst;
+      break;
+  }
+#  endif
+# else
+#  if RGB_RED != 0 || RGB_GREEN != 1 || RGB_BLUE != 2 || RGB_PIXELSIZE != 3
+#   error Unsupported libjpeg setup
+#  endif
+  info.out_color_space = JCS_RGB;
+  switch (request.format) {
+    case Image::Format::RGBA_8888:
+    case Image::Format::BGRA_8888:
+      format = Image::Format::RGBA_8888;
+      conversion = Conversion::kAddAlphaLast;
+      break;
+    case Image::Format::ABGR_8888:
+    case Image::Format::ARGB_8888:
+      format = Image::Format::ARGB_8888;
+      conversion = Conversion::kAddAlphaFirst;
+      break;
+  }
+# endif
+
+  if (request.max_width || request.max_height) {
+    auto new_size = rescale(Size{info.image_width, info.image_height},
+                            request.max_width, request.max_height);
+    unsigned int denom = 2;
+    while (info.image_width / denom >= new_size.width &&
+           info.image_height / denom >= new_size.height) {
+      info.scale_denom = denom;
+      denom *= 2;
+    }
+  }
+
+  jpeg_start_decompress(&info);
+
+  size_t scanline = static_cast<size_t>(info.output_width) * 4;
+  auto pixels = std::make_unique<uint8_t[]>(scanline * info.output_height);
+
+  auto buffer = std::make_unique<JSAMPROW[]>(info.rec_outbuf_height);
+
+  while (info.output_scanline < info.output_height) {
+    int buf_height = 1;
+    buffer[0] = reinterpret_cast<JSAMPROW>(pixels.get() +
+                                           (info.output_scanline * scanline));
+    while (buf_height < info.rec_outbuf_height &&
+           info.output_scanline + buf_height < info.output_height) {
+      buffer[buf_height] = reinterpret_cast<JSAMPROW>(
+          pixels.get() + ((info.output_scanline + buf_height) * scanline));
+      ++buf_height;
+    }
+    jpeg_read_scanlines(&info, buffer.get(), buf_height);
+  }
+
+  switch (conversion) {
+    case Conversion::kNone:
+      break;
+    case Conversion::kAddAlphaFirst:
+      insert_alpha_bytes(std::span{pixels.get(), scanline * info.output_height},
+                         info.output_width, info.output_height, scanline, 0);
+      break;
+    case Conversion::kAddAlphaLast:
+      insert_alpha_bytes(std::span{pixels.get(), scanline * info.output_height},
+                         info.output_width, info.output_height, scanline, 3);
+      break;
+    case Conversion::kSetAlphaFirst:
+      set_alpha_bytes(std::span{pixels.get(), scanline * info.output_height},
+                      info.output_width, info.output_height, scanline, 0);
+      break;
+    case Conversion::kSetAlphaLast:
+      set_alpha_bytes(std::span{pixels.get(), scanline * info.output_height},
+                      info.output_width, info.output_height, scanline, 3);
+      break;
+  }
+
+  Response resp{.width = info.output_width, .height = info.output_height, .error = 0, .scanline = scanline};
+  jpeg_destroy_decompress(&info);
+  fclose(fh);
+  return Result{.response = resp, .format = output_format, .pixels = std::move(pixels)};
+}
+#endif
+
+#if HAVE_PNG
+// NOLINTBEGIN(misc-include-cleaner)
+void png_error(png_structp png_ptr, png_const_charp /* message */) {
+  // Don't write anything
+  longjmp(png_jmpbuf(png_ptr), 1);
+}
+
+void png_warning(png_structp /* png_ptr */, png_const_charp /* message */) {
+  // Do nothing
+}
+
+std::expected<Result, ImageLoadError> load_png(
+    std::filesystem::path const& path, Request const& request) {
+  FILE* fh = fopen(path.c_str(), "rb");
+  if (fh == nullptr) {
+    if (errno == ENOENT) {
+      return std::unexpected(ImageLoadError::kNoSuchFile);
+    }
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  uint8_t header[8];
+  if (fread(header, 1, sizeof(header), fh) != sizeof(header)) {
+    fclose(fh);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  if (png_sig_cmp(header, 0, sizeof(header))) {
+    fclose(fh);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr,
+                                               png_error, png_warning);
+
+  if (!png_ptr) {
+    fclose(fh);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  png_infop info_ptr = png_create_info_struct(png_ptr);
+  if (!info_ptr) {
+    png_destroy_read_struct(&png_ptr, nullptr, nullptr);
+    fclose(fh);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  if (setjmp(png_jmpbuf(png_ptr))) {
+    png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
+    fclose(fh);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  png_init_io(png_ptr, fh);
+  png_set_sig_bytes(png_ptr, sizeof(header));
+
+  png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
+
+  png_read_info(png_ptr, info_ptr);
+
+  png_uint_32 width;
+  png_uint_32 height;
+  int bit_depth;
+  int color_type;
+
+  png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
+               nullptr, nullptr, nullptr);
+
+  if (request.head) {
+    Response resp{.width =width, .height = height, .error = 0, .scanline = 0};
+    png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
+    fclose(fh);
+    return Result{.response = resp, .format = Image::Format::RGBA_8888, .pixels = nullptr};
+  }
+
+  if (request.background != 0) {
+    png_color_16 background_color;
+    Colour colour{request.background};
+    background_color.red = colour.red() << 8 | colour.red();
+    background_color.green = colour.green() << 8 | colour.green();
+    background_color.blue = colour.blue() << 8 | colour.blue();
+    png_set_background(png_ptr, &background_color, PNG_BACKGROUND_GAMMA_SCREEN,
+                       0, 1);
+  } else {
+    png_color_16p background_color;
+    if (png_get_bKGD(png_ptr, info_ptr, &background_color))
+      png_set_background(png_ptr, background_color, PNG_BACKGROUND_GAMMA_FILE,
+                         1, 1);
+  }
+
+  if (color_type == PNG_COLOR_TYPE_PALETTE)
+    png_set_palette_to_rgb(png_ptr);
+
+  if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
+    png_set_tRNS_to_alpha(png_ptr);
+
+  if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
+    png_set_expand_gray_1_2_4_to_8(png_ptr);
+
+  if (bit_depth == 16)
+    png_set_scale_16(png_ptr);
+
+  if (color_type == PNG_COLOR_TYPE_GRAY ||
+      color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+    png_set_gray_to_rgb(png_ptr);
+
+  switch (request.format) {
+    case Image::Format::RGBA_8888:
+      png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
+      break;
+    case Image::Format::ARGB_8888:
+      png_set_swap_alpha(png_ptr);
+      png_set_filler(png_ptr, 0xff, PNG_FILLER_BEFORE);
+      break;
+    case Image::Format::BGRA_8888:
+      png_set_bgr(png_ptr);
+      png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
+      break;
+    case Image::Format::ABGR_8888:
+      png_set_bgr(png_ptr);
+      png_set_swap_alpha(png_ptr);
+      png_set_filler(png_ptr, 0xff, PNG_FILLER_BEFORE);
+      break;
+  }
+
+  png_read_update_info(png_ptr, info_ptr);
+
+  width = png_get_image_width(png_ptr, info_ptr);
+  height = png_get_image_height(png_ptr, info_ptr);
+  bit_depth = png_get_bit_depth(png_ptr, info_ptr);
+  color_type = png_get_color_type(png_ptr, info_ptr);
+  size_t scanline = png_get_rowbytes(png_ptr, info_ptr);
+
+  /* Guard against integer overflow */
+  if (height > PNG_SIZE_MAX / scanline)
+    png_error(png_ptr, "image_data buffer would be too large");
+
+  auto pixels = std::make_unique<uint8_t[]>(scanline * height);
+  auto rows = std::make_unique<png_bytep[]>(height);
+
+  for (png_uint_32 y = 0; y < height; ++y)
+    rows[y] = pixels.get() + (y * scanline);
+
+  png_read_image(png_ptr, rows.get());
+
+  png_read_end(png_ptr, nullptr);
+
+  png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
+
+  fclose(fh);
+
+  Response resp{.width = width, .height = height, .error = 0, .scanline = scanline};
+  return Result{.response = resp, .format = request.format, .pixels = std::move(pixels)};
+}
+// NOLINTEND(misc-include-cleaner)
+#endif
+
+#if HAVE_RSVG
+std::expected<Result, ImageLoadError> load_svg(
+    std::filesystem::path const& path, Request const& request) {
+  GFile* file = g_file_new_for_path(path.c_str());
+  if (!file) {
+    return std::unexpected(ImageLoadError::kNoSuchFile);
+  }
+  RsvgHandle* handle =
+      rsvg_handle_new_from_gfile_sync(file, RSVG_HANDLE_FLAGS_NONE, nullptr, nullptr);
+
+  if (!handle) {
+    g_object_unref(file);
+    return std::unexpected(ImageLoadError::kError);
+  }
+  g_object_unref(file);
+
+  // TODO: Get this as part of the request?
+  rsvg_handle_set_dpi(handle, 96.0);
+
+  Size size;
+  {
+    gdouble width_double;  // NOLINT(misc-include-cleaner)
+    gdouble height_double;  // NOLINT(misc-include-cleaner)
+    if (!rsvg_handle_get_intrinsic_size_in_pixels(handle, &width_double,
+                                                  &height_double)) {
+      g_object_unref(handle);
+      return std::unexpected(ImageLoadError::kError);
+    }
+    size.width = static_cast<uint32_t>(ceil(width_double));
+    size.height = static_cast<uint32_t>(ceil(height_double));
+  }
+
+  if (request.head) {
+    Response resp{.width = size.width, .height = size.height, .error = 0, .scanline = 0};
+    g_object_unref(handle);
+    return Result{.response = resp, .format = Image::Format::RGBA_8888, .pixels = nullptr};
+  }
+
+  if (request.max_width || request.max_height) {
+    size = rescale(size, request.max_width, request.max_height);
+  }
+
+  size_t scanline = static_cast<size_t>(size.width) * 4;
+  auto pixels = std::make_unique<uint8_t[]>(scanline * size.height);
+
+  cairo_surface_t* surface = cairo_image_surface_create_for_data(
+      reinterpret_cast<unsigned char*>(pixels.get()), CAIRO_FORMAT_ARGB32,
+      static_cast<int>(size.width), static_cast<int>(size.height),
+      static_cast<int>(scanline));
+
+  if (!surface) {
+    g_object_unref(handle);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  cairo_t* cr = cairo_create(surface);
+
+  if (request.background) {
+    cairo_rectangle(cr, 0, 0, size.width, size.height);
+    Colour colour{request.background};
+    cairo_set_source_rgba(cr, colour.red() / 255.0, colour.green() / 255.0,
+                          colour.blue() / 255.0, colour.alpha() / 255.0);
+    cairo_fill(cr);
+  }
+
+  RsvgRectangle viewport = {
+    .x = 0.0,
+    .y = 0.0,
+    .width = static_cast<double>(size.width),
+    .height = static_cast<double>(size.height),
+  };
+
+  if (!rsvg_handle_render_document(handle, cr, &viewport, nullptr)) {
+    cairo_destroy(cr);
+    cairo_surface_destroy(surface);
+    g_object_unref(handle);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  cairo_destroy(cr);
+  cairo_surface_destroy(surface);
+  g_object_unref(handle);
+
+  // Cairo uses premultiplied pixels, we don't
+  {
+    uint8_t* row = pixels.get();
+    for (uint32_t y = 0; y < size.height; ++y) {
+      uint8_t* pixel = row;
+      for (uint32_t x = 0; x < size.width; ++x, pixel += 4) {
+        if constexpr (std::endian::native == std::endian::big) {
+          if (pixel[0] != 0xff && pixel[0] > 0) {
+            pixel[1] = (static_cast<uint16_t>(pixel[1]) * 255) / pixel[0];
+            pixel[2] = (static_cast<uint16_t>(pixel[2]) * 255) / pixel[0];
+            pixel[3] = (static_cast<uint16_t>(pixel[3]) * 255) / pixel[0];
+          }
+        } else {
+          if (pixel[3] != 0xff && pixel[3] > 0) {
+            pixel[0] = (static_cast<uint16_t>(pixel[0]) * 255) / pixel[3];
+            pixel[1] = (static_cast<uint16_t>(pixel[1]) * 255) / pixel[3];
+            pixel[2] = (static_cast<uint16_t>(pixel[2]) * 255) / pixel[3];
+          }
+        }
+      }
+      row += scanline;
+    }
+  }
+
+  return Result{
+    .response = Response{.width = size.width, .height = size.height, .error = 0, .scanline = scanline},
+    .format = std::endian::native == std::endian::big ? Image::Format::ARGB_8888
+    : Image::Format::BGRA_8888,
+    .pixels = std::move(pixels)
+  };
+}
+#endif
+
+#if HAVE_XPM
+
+std::optional<uint32_t> xpm_parse_color(XpmColor const& color) {
+  if (color.c_color) {
+    auto const len = strlen(color.c_color);
+    if (color.c_color[0] == '#' && len == 7) {
+      uint32_t rgb;
+      if (std::from_chars(color.c_color + 1, color.c_color + 7, rgb, 16).ec == std::errc()) {
+        return 0xff000000 | rgb;
+      }
+    }
+    if (len == 4 && (strcmp(color.c_color, "None") == 0 ||
+                     strcmp(color.c_color, "none") == 0))
+      return 0;
+    unsigned short red;
+    unsigned short green;
+    unsigned short blue;
+    if (dixLookupBuiltinColor(0, color.c_color, len,
+                              &red, &green, &blue)) {
+      return 0xff000000 | (static_cast<uint32_t>(red & 0xff) << 16) |
+          (green & 0xff00) | (blue & 0xff);
+    }
+  }
+  if (color.m_color) {
+    if (strcmp(color.m_color, "white") == 0) {
+      return 0xffffffff;
+    }
+    if (strcmp(color.m_color, "black") == 0) {
+      return 0xff000000;
+    }
+  }
+  return std::nullopt;
+}
+
+std::expected<Result, ImageLoadError> load_xpm(
+    std::filesystem::path const& path, Request const& request) {
+  XpmImage image;
+  XpmInfo info;
+  auto ret = XpmReadFileToXpmImage(path.c_str(), &image, &info);
+  if (ret != XpmSuccess) {
+    if (ret == XpmOpenFailed)
+      return std::unexpected(ImageLoadError::kNoSuchFile);
+    return std::unexpected(ImageLoadError::kError);
+  }
+
+  if (request.head) {
+    Response resp{.width = image.width, .height = image.height, .error = 0, .scanline = 0};
+    XpmFreeXpmImage(&image);
+    XpmFreeXpmInfo(&info);
+    return Result{.response = resp, .format = Image::Format::RGBA_8888, .pixels = nullptr};
+  }
+
+  size_t scanline = static_cast<size_t>(image.width) * 4;
+  auto pixels = std::make_unique<uint8_t[]>(scanline * image.height);
+
+  auto colors = std::make_unique<uint32_t[]>(image.ncolors);
+  for (unsigned int i = 0; i < image.ncolors; ++i) {
+    auto ret = xpm_parse_color(image.colorTable[i]);
+    if (ret.has_value()) {
+      colors[i] = ret.value();
+    } else {
+      return std::unexpected(ImageLoadError::kUnsupportedFormat);
+    }
+  }
+
+  auto* out_row = pixels.get();
+  auto* in = image.data;
+  for (unsigned int y = 0; y < image.height; ++y) {
+    auto* out_pixel = reinterpret_cast<uint32_t*>(out_row);
+    for (unsigned int x = 0; x < image.width; ++x) {
+      out_pixel[x] = colors[*in++];
+    }
+    out_row += scanline;
+  }
+
+  XpmFreeXpmImage(&image);
+  XpmFreeXpmInfo(&info);
+
+  return Result{
+    .response = Response{.width = image.width, .height = image.height, .error = 0, .scanline = scanline},
+    .format = std::endian::native == std::endian::big ? Image::Format::ARGB_8888 : Image::Format::BGRA_8888,
+    .pixels = std::move(pixels),
+  };
+}
+#endif
+
+}  // namespace
+
+namespace image_processor {
+
+std::expected<Size, ImageLoadError> peek(Process& process,
+                                         std::filesystem::path const& path) {
+  auto ret = write_request(process.writer(), path, true,
+                           Image::Format::ARGB_8888, 0, 0, {});
+  if (!ret) {
+    return std::unexpected(ret.error());
+  }
+  auto ret2 = read_response(process.reader());
+  if (!ret2)
+    return std::unexpected(ret2.error());
+  return Size{ret2->width, ret2->height};
+}
+
+std::expected<std::unique_ptr<Image>, ImageLoadError> load(
+    Process& process, std::filesystem::path const& path, Image::Format format,
+    uint32_t max_width, uint32_t max_height, std::optional<Colour> background) {
+  auto ret = write_request(process.writer(), path, false, format, max_width,
+                           max_height, background.value_or({}));
+  if (!ret) {
+    return std::unexpected(ret.error());
+  }
+  auto ret2 = read_response(process.reader());
+  if (!ret2)
+    return std::unexpected(ret2.error());
+  size_t size = static_cast<size_t>(ret2->height) * ret2->scanline;
+  auto pixels = std::make_unique<uint8_t[]>(size);
+  auto ret3 = process.reader().repeat_read(pixels.get(), size);
+  if (!ret3.has_value() || ret3.value() != size) {
+    return std::unexpected(ret.error());
+  }
+  return std::make_unique<Image>(format, Size{ret2->width, ret2->height},
+                                 ret2->scanline, std::move(pixels));
+}
+
+int run(std::unique_ptr<io::Reader> reader,
+        std::unique_ptr<io::Writer> writer) {
+  while (true) {
+    Request request;
+    auto ret = reader->repeat_read(&request, sizeof(request));
+    if (!ret.has_value() || ret.value() != sizeof(request))
+      break;
+    std::string path_str(request.path_len, ' ');
+    ret = reader->repeat_read(path_str.data(), path_str.size());
+    if (!ret.has_value() || ret.value() != path_str.size())
+      break;
+    std::filesystem::path path(std::move(path_str));
+
+    auto extension = path.extension().native();
+    std::ranges::transform(extension, extension.begin(),
+                           [](unsigned char c){ return std::tolower(c); });
+    std::expected<Result, ImageLoadError> result{
+      std::unexpected(ImageLoadError::kUnsupportedFormat)};
+#if HAVE_JPEG
+    if (extension == ".jpeg" || extension == ".jpg" || extension == ".jpe" ||
+        extension == ".jfif" || extension == ".jfi" || extension == ".jif") {
+      result = load_jpeg(path, request);
+    }
+#endif
+#if HAVE_PNG
+    if (path.extension() == ".png") {
+      result = load_png(path, request);
+    }
+#endif
+#if HAVE_RSVG
+    if (path.extension() == ".svg" || path.extension() == ".svgz") {
+      result = load_svg(path, request);
+    }
+#endif
+#if HAVE_XPM
+    if (path.extension() == ".xpm") {
+      result = load_xpm(path, request);
+    }
+#endif
+    if (!request.head && result.has_value() &&
+        result->format != request.format) {
+      auto size = static_cast<size_t>(result->response.height) *
+                  result->response.scanline;
+      rearrange_bytes(std::span(result->pixels.get(), size),
+                      result->response.width, result->response.height,
+                      result->response.scanline, result->format,
+                      request.format);
+    }
+    if (result.has_value()) {
+      auto ret2 =
+          writer->repeat_write(&result->response, sizeof(result->response));
+      if (!ret2.has_value() || ret2.value() != sizeof(result->response))
+        break;
+      if (!request.head) {
+        auto size = static_cast<size_t>(result->response.height) *
+                    result->response.scanline;
+        ret2 = writer->repeat_write(result->pixels.get(), size);
+        if (!ret2.has_value() || ret2.value() != size)
+          break;
+      }
+    } else {
+      Response response{.width = 0, .height = 0, .error = static_cast<uint8_t>(result.error()), .scanline = 0};
+      auto ret2 = writer->repeat_write(&response, sizeof(response));
+      if (!ret2.has_value() || ret2.value() != sizeof(response))
+        break;
+    }
+  }
+  return -1;
+}
+
+}  // namespace image_processor
diff --git a/src/image_processor.hh b/src/image_processor.hh
new file mode 100644
index 0000000..551ac4f
--- /dev/null
+++ b/src/image_processor.hh
@@ -0,0 +1,29 @@
+#ifndef IMAGE_PROCESSOR_HH
+#define IMAGE_PROCESSOR_HH
+
+#include "colour.hh"
+#include "image_loader.hh"
+#include "io.hh"
+#include "spawner.hh"
+
+#include <filesystem>
+#include <memory>
+#include <optional>
+
+namespace image_processor {
+
+[[nodiscard]]
+std::expected<Size, ImageLoadError> peek(Process& process,
+                                         std::filesystem::path const& path);
+
+[[nodiscard]]
+std::expected<std::unique_ptr<Image>, ImageLoadError> load(
+    Process& process, std::filesystem::path const& path, Image::Format format,
+    uint32_t max_width = 0, uint32_t max_height = 0,
+    std::optional<Colour> background = std::nullopt);
+
+int run(std::unique_ptr<io::Reader> reader, std::unique_ptr<io::Writer> writer);
+
+}  // namespace image_processor
+
+#endif  // IMAGE_PROCESSOR_HH
diff --git a/src/io.cc b/src/io.cc
new file mode 100644
index 0000000..660c5f7
--- /dev/null
+++ b/src/io.cc
@@ -0,0 +1,358 @@
+#include "io.hh"
+
+#include "unique_fd.hh"
+
+#include <algorithm>
+#include <cerrno>
+#include <cstdio>
+#include <cstring>
+#include <expected>
+#include <fcntl.h>
+#include <limits>
+#include <memory>
+#include <optional>
+#include <string>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <utility>
+
+namespace io {
+
+namespace {
+
+class BasicReader : public Reader {
+ public:
+  explicit BasicReader(unique_fd fd) : fd_(std::move(fd)) {}
+
+  [[nodiscard]]
+  std::expected<size_t, ReadError> read(void* dst, size_t max) override {
+    ssize_t ret = ::read(
+        fd_.get(), dst,
+        std::min(static_cast<size_t>(std::numeric_limits<ssize_t>::max()),
+                 max));
+    if (ret < 0) {
+      switch (errno) {
+        case EINTR:
+          return read(dst, max);
+        default:
+          return std::unexpected(ReadError::Error);
+      }
+    } else if (ret == 0 && max > 0) {
+      return std::unexpected(ReadError::Eof);
+    }
+    offset_ += ret;
+    return ret;
+  }
+
+  [[nodiscard]]
+  std::expected<size_t, ReadError> skip(size_t max) override {
+    off_t ret;
+    if (sizeof(size_t) > sizeof(off_t)) {
+      ret = lseek(
+          fd_.get(),
+          // NOLINTNEXTLINE(bugprone-narrowing-conversions)
+          std::min(static_cast<size_t>(std::numeric_limits<off_t>::max()), max),
+          SEEK_CUR);
+    } else {
+      ret = lseek(fd_.get(), static_cast<off_t>(max), SEEK_CUR);
+    }
+    if (ret < 0) {
+      return std::unexpected(ReadError::Error);
+    }
+    // Don't want skip to go past (cached) file end.
+    if (!size_.has_value() || ret >= size_.value()) {
+      // When going past end, double check that it still is the end.
+      off_t ret2 = lseek(fd_.get(), 0, SEEK_END);
+      if (ret2 < 0) {
+        // We're screwed, but try to go back to original position and then
+        // return error.
+        size_.reset();
+        lseek(fd_.get(), offset_, SEEK_SET);
+        return std::unexpected(ReadError::Error);
+      }
+      size_ = ret2;
+      if (ret >= ret2) {
+        auto distance = ret2 - offset_;
+        offset_ = ret2;
+        if (distance == 0 && max > 0)
+          return std::unexpected(ReadError::Eof);
+        return distance;
+      }
+      // Seek back to where we should be
+      if (lseek(fd_.get(), ret, SEEK_SET) < 0) {
+        return std::unexpected(ReadError::Error);
+      }
+    }
+    auto distance = ret - offset_;
+    offset_ = ret;
+    return distance;
+  }
+
+  [[nodiscard]]
+  int raw_fd() const override {
+    return fd_.get();
+  }
+
+ private:
+  unique_fd fd_;
+  off_t offset_{0};
+  std::optional<off_t> size_;
+};
+
+class MemoryReader : public Reader {
+ public:
+  MemoryReader(void* ptr, size_t size) : ptr_(ptr), size_(size) {}
+
+  [[nodiscard]]
+  std::expected<size_t, ReadError> read(void* dst, size_t max) override {
+    size_t avail = size_ - offset_;
+    if (avail == 0 && max > 0)
+      return std::unexpected(io::ReadError::Eof);
+    size_t ret = std::min(max, avail);
+    memcpy(dst, reinterpret_cast<char*>(ptr_) + offset_, ret);
+    offset_ += ret;
+    return ret;
+  }
+
+  [[nodiscard]]
+  std::expected<size_t, ReadError> skip(size_t max) override {
+    size_t avail = size_ - offset_;
+    size_t ret = std::min(max, avail);
+    offset_ += ret;
+    return ret;
+  }
+
+  [[nodiscard]]
+  int raw_fd() const override {
+    return -1;
+  }
+
+ protected:
+  void* ptr_;
+  size_t const size_;
+
+ private:
+  size_t offset_{0};
+};
+
+class MmapReader : public MemoryReader {
+ public:
+  MmapReader(unique_fd fd, void* ptr, size_t size)
+      : MemoryReader(ptr, size), fd_(std::move(fd)) {}
+
+  ~MmapReader() override { munmap(ptr_, size_); }
+
+  [[nodiscard]]
+  int raw_fd() const override {
+    return fd_.get();
+  }
+
+ private:
+  unique_fd fd_;
+};
+
+class StringReader : public MemoryReader {
+ public:
+  explicit StringReader(std::string data)
+      : MemoryReader(nullptr, data.size()), data_(std::move(data)) {
+    ptr_ = data_.data();
+  }
+
+ private:
+  std::string data_;
+};
+
+class BasicWriter : public Writer {
+ public:
+  explicit BasicWriter(unique_fd fd) : fd_(std::move(fd)) {}
+
+  [[nodiscard]]
+  std::expected<size_t, WriteError> write(void const* dst,
+                                          size_t size) override {
+    ssize_t ret = ::write(
+        fd_.get(), dst,
+        std::min(static_cast<size_t>(std::numeric_limits<ssize_t>::max()),
+                 size));
+    if (ret < 0) {
+      switch (errno) {
+        case EINTR:
+          return write(dst, size);
+        default:
+          return std::unexpected(WriteError::Error);
+      }
+    } else if (ret == 0 && size > 0) {
+      return std::unexpected(WriteError::Error);
+    }
+    return ret;
+  }
+
+  [[nodiscard]]
+  std::expected<void, WriteError> close() override {
+    if (::close(fd_.release()) == 0)
+      return {};
+    return std::unexpected(WriteError::Error);
+  }
+
+  [[nodiscard]]
+  int raw_fd() const override {
+    return fd_.get();
+  }
+
+ private:
+  unique_fd fd_;
+};
+
+}  // namespace
+
+std::expected<size_t, ReadError> Reader::repeat_read(void* dst, size_t max) {
+  auto ret = read(dst, max);
+  if (!ret.has_value() || ret.value() == max)
+    return ret;
+
+  char* d = reinterpret_cast<char*>(dst);
+  size_t offset = ret.value();
+  while (true) {
+    ret = read(d + offset, max - offset);
+    if (!ret.has_value())
+      break;
+    offset += ret.value();
+    if (offset == max)
+      break;
+  }
+  return offset;
+}
+
+std::expected<size_t, ReadError> Reader::repeat_skip(size_t max) {
+  auto ret = skip(max);
+  if (!ret.has_value() || ret.value() == max)
+    return ret;
+
+  size_t offset = ret.value();
+  while (true) {
+    ret = skip(max - offset);
+    if (!ret.has_value())
+      break;
+    offset += ret.value();
+    if (offset == max)
+      break;
+  }
+  return offset;
+}
+
+std::expected<size_t, WriteError> Writer::repeat_write(void const* dst,
+                                                       size_t size) {
+  auto ret = write(dst, size);
+  if (!ret.has_value() || ret.value() == size)
+    return ret;
+
+  char const* d = reinterpret_cast<char const*>(dst);
+  size_t offset = ret.value();
+  while (true) {
+    ret = write(d + offset, size - offset);
+    if (!ret.has_value())
+      break;
+    offset += ret.value();
+    if (offset == size)
+      break;
+  }
+  return offset;
+}
+
+std::expected<std::unique_ptr<Reader>, OpenError> open(
+    const std::string& file_path) {
+  return openat(AT_FDCWD, file_path);
+}
+
+std::expected<std::unique_ptr<Reader>, OpenError> openat(
+    int dirfd, const std::string& file_path) {
+  unique_fd fd(::openat(dirfd, file_path.c_str(), O_RDONLY));
+  if (fd) {
+    struct stat buf;
+    if (fstat(fd.get(), &buf) == 0) {
+      if (std::cmp_less_equal(buf.st_size,
+                              std::numeric_limits<size_t>::max())) {
+        auto size = static_cast<size_t>(buf.st_size);
+        void* ptr = mmap(nullptr, size, PROT_READ, MAP_PRIVATE, fd.get(), 0);
+        if (ptr != MAP_FAILED) {
+          return std::make_unique<MmapReader>(std::move(fd), ptr, size);
+        }
+      }
+    }
+    return std::make_unique<BasicReader>(std::move(fd));
+  }
+  OpenError err;
+  switch (errno) {
+    case EINTR:
+      return openat(dirfd, file_path);
+    case EACCES:
+      err = OpenError::NoAccess;
+      break;
+    case ENOENT:
+      err = OpenError::NoSuchFile;
+      break;
+    default:
+      err = OpenError::Error;
+      break;
+  }
+  return std::unexpected(err);
+}
+
+std::unique_ptr<Reader> memory(std::string data) {
+  return std::make_unique<StringReader>(std::move(data));
+}
+
+std::expected<std::unique_ptr<Writer>, CreateError> create(
+    const std::string& file_path, bool replace_existing) {
+  return createat(AT_FDCWD, file_path, replace_existing);
+}
+
+std::expected<std::unique_ptr<Writer>, CreateError> createat(
+    int dirfd, const std::string& file_path, bool replace_existing) {
+  int flags = O_WRONLY | O_CREAT;
+  if (replace_existing) {
+    flags |= O_TRUNC;
+  } else {
+    flags |= O_EXCL;
+  }
+  unique_fd fd(::openat(dirfd, file_path.c_str(), flags, 0666));
+  if (fd) {
+    return std::make_unique<BasicWriter>(std::move(fd));
+  }
+  CreateError err;
+  switch (errno) {
+    case EINTR:
+      return createat(dirfd, file_path, replace_existing);
+    case EACCES:
+      err = CreateError::NoAccess;
+      break;
+    case EEXIST:
+      err = CreateError::Exists;
+      break;
+    default:
+      err = CreateError::Error;
+      break;
+  }
+  return std::unexpected(err);
+}
+
+std::expected<std::pair<std::unique_ptr<Reader>, std::unique_ptr<Writer>>,
+              PipeError>
+pipe() {
+  int fds[2];
+  if (::pipe(fds) == 0) {
+    return std::make_pair(reader_from_raw(fds[0]), writer_from_raw(fds[1]));
+  }
+  return std::unexpected(PipeError::Error);
+}
+
+std::unique_ptr<Reader> reader_from_raw(int fd) {
+  return std::make_unique<BasicReader>(unique_fd{fd});
+}
+
+std::unique_ptr<Writer> writer_from_raw(int fd) {
+  return std::make_unique<BasicWriter>(unique_fd{fd});
+}
+
+}  // namespace io
diff --git a/src/io.hh b/src/io.hh
new file mode 100644
index 0000000..90ad52e
--- /dev/null
+++ b/src/io.hh
@@ -0,0 +1,109 @@
+#ifndef IO_HH
+#define IO_HH
+
+#include <cstddef>
+#include <expected>
+#include <memory>
+#include <string>
+#include <utility>
+
+namespace io {
+
+enum class ReadError : uint8_t {
+  Error,
+  Eof,
+  InvalidData,  // invalid data read (not used by raw file)
+  MaxTooSmall,  // max argument needs to be bigger (not used by raw file)
+};
+
+enum class WriteError : uint8_t {
+  Error,
+};
+
+enum class OpenError : uint8_t {
+  NoSuchFile,
+  NoAccess,
+  Error,
+};
+
+enum class CreateError : uint8_t {
+  Exists,
+  NoAccess,
+  Error,
+};
+
+enum class PipeError : uint8_t {
+  Error,
+};
+
+class Reader {
+ public:
+  virtual ~Reader() = default;
+
+  [[nodiscard]] virtual std::expected<size_t, ReadError> read(void* dst,
+                                                              size_t max) = 0;
+  [[nodiscard]] virtual std::expected<size_t, ReadError> skip(size_t max) = 0;
+
+  [[nodiscard]] std::expected<size_t, ReadError> repeat_read(void* dst,
+                                                             size_t max);
+  [[nodiscard]] std::expected<size_t, ReadError> repeat_skip(size_t max);
+
+  [[nodiscard]]
+  virtual int raw_fd() const = 0;
+
+ protected:
+  Reader() = default;
+
+  Reader(Reader const&) = delete;
+  Reader& operator=(Reader const&) = delete;
+};
+
+class Writer {
+ public:
+  virtual ~Writer() = default;
+
+  [[nodiscard]]
+  virtual std::expected<size_t, WriteError> write(void const* dst,
+                                                  size_t size) = 0;
+
+  // Use this instead of the destructor if you care if the call returned an
+  // error or not. Regardless of returned value, after this method is called
+  // write will always fail.
+  [[nodiscard]]
+  virtual std::expected<void, WriteError> close() = 0;
+
+  [[nodiscard]]
+  virtual int raw_fd() const = 0;
+
+  [[nodiscard]] std::expected<size_t, WriteError> repeat_write(void const* dst,
+                                                               size_t size);
+
+ protected:
+  Writer() = default;
+
+  Writer(Writer const&) = delete;
+  Writer& operator=(Writer const&) = delete;
+};
+
+[[nodiscard]] std::expected<std::unique_ptr<Reader>, OpenError> open(
+    const std::string& file_path);
+[[nodiscard]] std::expected<std::unique_ptr<Reader>, OpenError> openat(
+    int dirfd, const std::string& file_path);
+[[nodiscard]] std::unique_ptr<Reader> memory(std::string data);
+
+[[nodiscard]] std::expected<std::unique_ptr<Writer>, CreateError> create(
+    const std::string& file_path, bool replace_existing);
+[[nodiscard]] std::expected<std::unique_ptr<Writer>, CreateError> createat(
+    int dirfd, const std::string& file_path, bool replace_existing);
+
+[[nodiscard]] std::expected<
+    std::pair<std::unique_ptr<Reader>, std::unique_ptr<Writer>>, PipeError>
+pipe();
+
+// Takes ownership of the fd.
+[[nodiscard]] std::unique_ptr<Reader> reader_from_raw(int fd);
+[[nodiscard]] std::unique_ptr<Writer> writer_from_raw(int fd);
+
+}  // namespace io
+
+#endif  // IO_HH
diff --git a/src/line.cc b/src/line.cc
new file mode 100644
index 0000000..23370fc
--- /dev/null
+++ b/src/line.cc
@@ -0,0 +1,127 @@
+#include "line.hh"
+
+#include "check.hh"
+
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <cstring>
+#include <expected>
+#include <memory>
+#include <string_view>
+#include <utility>
+
+namespace line {
+
+namespace {
+
+const char kLineTerminators[] = "\r\n";
+
+class ReaderImpl : public Reader {
+ public:
+  ReaderImpl(std::unique_ptr<io::Reader> reader, size_t max_len)
+      : reader_(std::move(reader)),
+        max_len_(max_len),
+        buffer_(std::make_unique_for_overwrite<char[]>(
+            check::add(max_len, static_cast<size_t>(2)))),
+        rptr_(buffer_.get()),
+        wptr_(buffer_.get()),
+        search_(rptr_),
+        end_(buffer_.get() + check::add(max_len, static_cast<size_t>(2))) {}
+
+  [[nodiscard]] std::expected<std::string_view, io::ReadError> read() override {
+    while (true) {
+      search_ = std::find_first_of(search_, wptr_, kLineTerminators,
+                                   kLineTerminators + 2);
+      if (search_ < wptr_) {
+        if (std::cmp_greater(search_ - rptr_, max_len_)) {
+          return line(max_len_, 0);
+        }
+
+        size_t tlen;
+        if (*search_ == '\n') {
+          tlen = 1;
+        } else {
+          if (search_ + 1 == wptr_) {
+            make_space_if_needed();
+            auto got = fill();
+            if (!got.has_value()) {
+              if (got.error() == io::ReadError::Eof) {
+                return line(search_ - rptr_, 1);
+              }
+              return std::unexpected(got.error());
+            }
+          }
+          if (search_[1] == '\n') {
+            tlen = 2;
+          } else {
+            tlen = 1;
+          }
+        }
+        return line(search_ - rptr_, tlen);
+      }
+      if (std::cmp_greater_equal(wptr_ - rptr_, max_len_)) {
+        return line(max_len_, 0);
+      }
+
+      make_space_if_needed();
+      auto got = fill();
+      if (!got.has_value()) {
+        if (got.error() == io::ReadError::Eof && rptr_ != wptr_) {
+          return line(wptr_ - rptr_, 0);
+        }
+        return std::unexpected(got.error());
+      }
+    }
+  }
+
+  [[nodiscard]] uint64_t number() const override { return number_; }
+
+ private:
+  std::string_view line(size_t len, size_t terminator_len) {
+    assert(len <= max_len_);
+    auto ret = std::string_view(rptr_, len);
+    rptr_ += len + terminator_len;
+    search_ = rptr_;
+    ++number_;
+    return ret;
+  }
+
+  void make_space_if_needed() {
+    size_t free = rptr_ - buffer_.get();
+    if (free == 0)
+      return;
+    size_t avail = end_ - wptr_;
+    if (avail > 1024)
+      return;
+    memmove(buffer_.get(), rptr_, wptr_ - rptr_);
+    search_ -= free;
+    wptr_ -= free;
+    rptr_ = buffer_.get();
+  }
+
+  std::expected<size_t, io::ReadError> fill() {
+    auto ret = reader_->read(wptr_, end_ - wptr_);
+    if (ret.has_value())
+      wptr_ += ret.value();
+    return ret;
+  }
+
+  std::unique_ptr<io::Reader> reader_;
+  size_t const max_len_;
+  uint64_t number_{0};
+  std::unique_ptr<char[]> buffer_;
+  char* rptr_;
+  char* wptr_;
+  char* search_;
+  char* const end_;
+};
+
+}  // namespace
+
+std::unique_ptr<Reader> open(std::unique_ptr<io::Reader> reader,
+                             size_t max_len) {
+  return std::make_unique<ReaderImpl>(std::move(reader), max_len);
+}
+
+}  // namespace line
diff --git a/src/line.hh b/src/line.hh
new file mode 100644
index 0000000..a8eeea8
--- /dev/null
+++ b/src/line.hh
@@ -0,0 +1,37 @@
+#ifndef LINE_HH
+#define LINE_HH
+
+#include "io.hh"  // IWYU pragma: export
+
+#include <cstddef>
+#include <expected>
+#include <memory>
+#include <optional>
+#include <string_view>
+
+namespace line {
+
+class Reader {
+ public:
+  virtual ~Reader() = default;
+
+  // Returned view is only valid until next call to read.
+  [[nodiscard]]
+  virtual std::expected<std::string_view, io::ReadError> read() = 0;
+  // Starts at zero. Returns next line.
+  // So, before first read it is zero, after first read it is one.
+  [[nodiscard]] virtual uint64_t number() const = 0;
+
+ protected:
+  Reader() = default;
+
+  Reader(Reader const&) = delete;
+  Reader& operator=(Reader const&) = delete;
+};
+
+[[nodiscard]] std::unique_ptr<Reader> open(std::unique_ptr<io::Reader> reader,
+                                           size_t max_len = 8192);
+
+}  // namespace line
+
+#endif  // LINE_HH
diff --git a/src/logger.cc b/src/logger.cc
new file mode 100644
index 0000000..e6198da
--- /dev/null
+++ b/src/logger.cc
@@ -0,0 +1,125 @@
+#include "logger.hh"
+
+#include <cstdint>
+#include <format>
+#include <iostream>
+#include <memory>
+#include <string>
+#include <string_view>
+#include <utility>
+
+namespace logger {
+
+namespace {
+
+class BaseLogger : public Logger {
+ protected:
+  enum class Level : uint8_t {
+    kError,
+    kWarning,
+    kInfo,
+    kDebug,
+  };
+
+ public:
+  void err(std::string_view message) final { write(Level::kError, message); }
+
+  void warn(std::string_view message) final { write(Level::kWarning, message); }
+
+  void info(std::string_view message) final { write(Level::kInfo, message); }
+
+#ifndef NDEBUG
+  void dbg(std::string_view message) final { write(Level::kDebug, message); }
+#endif
+
+ protected:
+  BaseLogger() = default;
+
+  virtual void write(Level level, std::string_view message) = 0;
+};
+
+class NoopLogger : public BaseLogger {
+ public:
+  NoopLogger() = default;
+
+ protected:
+  void write(Level /* level */, std::string_view /* message */) override {}
+};
+
+class StderrLogger : public BaseLogger {
+ public:
+  explicit StderrLogger(bool verbose) : verbose_(verbose) {}
+
+ protected:
+  void write(Level level, std::string_view message) override {
+    switch (level) {
+      case Level::kError:
+        std::cerr << "Error: ";
+        break;
+      case Level::kWarning:
+        std::cerr << "Warning: ";
+        break;
+      case Level::kInfo:
+        if (!verbose_)
+          return;
+        std::cerr << "Info: ";
+        break;
+      case Level::kDebug:
+        if (!verbose_)
+          return;
+        std::cerr << "Debug: ";
+        break;
+    }
+    std::cerr << message << '\n';
+  }
+
+ private:
+  bool const verbose_;
+};
+
+class PrefixLogger : public Logger {
+ public:
+  PrefixLogger(Logger& logger, std::string prefix)
+      : logger_(logger), prefix_(std::move(prefix)) {}
+
+  void err(std::string_view message) override {
+    logger_.err(std::format("{}: {}", prefix_, message));
+  }
+
+  void warn(std::string_view message) override {
+    logger_.warn(std::format("{}: {}", prefix_, message));
+  }
+
+  void info(std::string_view message) override {
+    logger_.info(std::format("{}: {}", prefix_, message));
+  }
+
+#ifndef NDEBUG
+  void dbg(std::string_view message) override {
+    logger_.dbg(std::format("{}: {}", prefix_, message));
+  }
+#endif
+
+ private:
+  Logger& logger_;
+  std::string prefix_;
+};
+
+}  // namespace
+
+[[nodiscard]]
+std::unique_ptr<Logger> noop() {
+  return std::make_unique<NoopLogger>();
+}
+
+[[nodiscard]]
+std::unique_ptr<Logger> stderr(bool verbose) {
+  return std::make_unique<StderrLogger>(verbose);
+}
+
+[[nodiscard]]
+std::unique_ptr<Logger> prefix(Logger& logger, std::string prefix) {
+  return std::make_unique<PrefixLogger>(logger, std::move(prefix));
+}
+
+}  // namespace logger
diff --git a/src/logger.hh b/src/logger.hh
new file mode 100644
index 0000000..df6879a
--- /dev/null
+++ b/src/logger.hh
@@ -0,0 +1,41 @@
+#ifndef LOGGER_HH
+#define LOGGER_HH
+
+#include <memory>
+#include <string>
+#include <string_view>
+
+namespace logger {
+
+class Logger {
+ public:
+  virtual ~Logger() = default;
+
+  virtual void err(std::string_view message) = 0;
+  virtual void warn(std::string_view message) = 0;
+  virtual void info(std::string_view message) = 0;
+
+#if defined(NDEBUG)
+  void dbg(std::string_view) {}
+#else
+  virtual void dbg(std::string_view message) = 0;
+#endif
+
+ protected:
+  Logger() = default;
+  Logger(Logger const&) = delete;
+  Logger& operator=(Logger const&) = delete;
+};
+
+[[nodiscard]]
+std::unique_ptr<Logger> noop();
+
+[[nodiscard]]
+std::unique_ptr<Logger> stderr(bool verbose = false);
+
+[[nodiscard]]
+std::unique_ptr<Logger> prefix(Logger& logger, std::string prefix);
+
+}  // namespace logger
+
+#endif  // LOGGER_HH
diff --git a/src/main.cc b/src/main.cc
new file mode 100644
index 0000000..9756c87
--- /dev/null
+++ b/src/main.cc
@@ -0,0 +1,47 @@
+#include "args.hh"
+#include "config.h"
+#include "image_processor.hh"
+#include "spawner.hh"
+
+#include <stdlib.h> // NOLINT(modernize-deprecated-headers)
+#include <iostream>
+#include <string_view>
+#include <vector>
+
+int main(int argc, char** argv) {
+  auto args = Args::create();
+  auto opt_help = args->option('h', "help", "display this text and exit");
+  auto opt_version = args->option('V', "version", "display version and exit");
+  std::vector<std::string_view> arguments;
+  if (!args->run(argc, argv, &arguments)) {
+    args->print_error(std::cerr);
+    std::cerr << "Try `sawmill --help` for usage.\n";
+    return EXIT_FAILURE;
+  }
+  if (opt_help->is_set()) {
+    std::cout << "Usage: `sawmill [OPTION]...`\n"
+              << "This is a window manager for Wayland.\n"
+              << "\n";
+    args->print_help(std::cout);
+    return EXIT_SUCCESS;
+  }
+  if (opt_version->is_set()) {
+    std::cout << "sawmill " << VERSION << " written by Joel Klinghed.\n";
+    return EXIT_SUCCESS;
+  }
+  auto spawner = Spawner::create();
+  if (spawner.has_value()) {
+    auto processor = spawner.value()->run(Spawner::Exec::kImageProcessor);
+    if (processor.has_value()) {
+      auto ret = image_processor::peek(**processor, "/home/the_jk/Downloads/image2vector.svg");
+      if (ret.has_value()) {
+        std::cout << ret->width << "x" << ret->height << '\n';
+      } else {
+        std::cerr << "Bad file\n";
+      }
+      return EXIT_SUCCESS;
+    }
+  }
+  std::cerr << "Unable to launch spawner.\n";
+  return EXIT_FAILURE;
+}
diff --git a/src/paths.cc b/src/paths.cc
new file mode 100644
index 0000000..091be6e
--- /dev/null
+++ b/src/paths.cc
@@ -0,0 +1,100 @@
+#include "paths.hh"
+
+#include "str.hh"
+
+#include <algorithm>
+#include <cerrno>
+#include <cstddef>
+#include <cstdlib>
+#include <iterator>
+#include <memory>
+#include <pwd.h>
+#include <string_view>
+#include <unistd.h>
+#include <unordered_set>
+#include <vector>
+
+namespace paths {
+
+namespace {
+
+std::vector<std::filesystem::path> xdg_read_dirs(
+    const char* userdir_env_name, std::string_view userdir_home_default,
+    const char* dirs_env_name,
+    std::vector<std::filesystem::path> const& dirs_default_value) {
+  std::vector<std::filesystem::path> ret;
+  std::unordered_set<std::filesystem::path> tmp;
+  auto* env_userdir = getenv(userdir_env_name);
+  if (env_userdir != nullptr && env_userdir[0] != '\0') {
+    ret.emplace_back(env_userdir);
+  } else {
+    ret.emplace_back(home() / userdir_home_default);
+  }
+  tmp.insert(ret.back());
+  auto* env_dirs = getenv(dirs_env_name);
+  if (env_dirs != nullptr && env_dirs[0] != '\0') {
+    for (auto dir : str::split(env_dirs, ':')) {
+      if (tmp.emplace(dir).second) {
+        ret.emplace_back(dir);
+      }
+    }
+  } else {
+    std::ranges::copy_if(
+        dirs_default_value, std::back_inserter(ret),
+        [&tmp](auto const& dir) { return tmp.emplace(dir).second; });
+  }
+  return ret;
+}
+
+}  // namespace
+
+std::filesystem::path home() {
+  {
+    auto* str = getenv("HOME");
+    if (str != nullptr && str[0] != '\0')
+      return str;
+  }
+
+  {
+    auto maybe_size = sysconf(_SC_GETPW_R_SIZE_MAX);
+    size_t size = maybe_size > 0 ? static_cast<size_t>(maybe_size) : 1024;
+    auto buffer = std::make_unique<char[]>(size);
+    struct passwd pwd;
+    struct passwd* ret;
+    int err;
+    while (true) {
+      err = getpwuid_r(geteuid(), &pwd, buffer.get(), size, &ret);
+      if (err == 0)
+        break;
+      if (err != ERANGE)
+        break;
+      auto new_size = size * 2;
+      if (new_size < size)
+        break;
+      buffer = std::make_unique<char[]>(new_size);
+      size = new_size;
+    }
+    if (err == 0 && ret) {
+      if (ret->pw_dir != nullptr && ret->pw_dir[0] != '\0') {
+        return ret->pw_dir;
+      }
+    }
+  }
+
+  return "/";
+}
+
+std::vector<std::filesystem::path> config_dirs() {
+  static const std::vector<std::filesystem::path> fallback{"/etc/xdg"};
+  return xdg_read_dirs("XDG_CONFIG_HOME", ".config", "XDG_CONFIG_DIRS",
+                       fallback);
+}
+
+std::vector<std::filesystem::path> data_dirs() {
+  static const std::vector<std::filesystem::path> fallback{"/usr/local/share/",
+                                                           "/usr/share/"};
+  return xdg_read_dirs("XDG_DATA_HOME", ".local/share", "XDG_DATA_DIRS",
+                       fallback);
+}
+
+}  // namespace paths
diff --git a/src/paths.hh b/src/paths.hh
new file mode 100644
index 0000000..8bd4c75
--- /dev/null
+++ b/src/paths.hh
@@ -0,0 +1,20 @@
+#ifndef PATHS_HH
+#define PATHS_HH
+
+#include <filesystem>  // IWYU pragma: export
+#include <vector>
+
+namespace paths {
+
+// Return home directory, goes HOME, /etc/passwd entry, / in that order.
+std::filesystem::path home();
+
+// Return config directories for reading, in order of priority.
+std::vector<std::filesystem::path> config_dirs();
+
+// Return data directories for reading, in order of priority.
+std::vector<std::filesystem::path> data_dirs();
+
+}  // namespace paths
+
+#endif  // PATHS_HH
diff --git a/src/size.hh b/src/size.hh
new file mode 100644
index 0000000..8fcc53f
--- /dev/null
+++ b/src/size.hh
@@ -0,0 +1,30 @@
+#ifndef SIZE_HH
+#define SIZE_HH
+
+#include <compare>
+#include <cstdint>
+
+struct Size final {
+  Size() : width(0), height(0) {}
+  Size(uint32_t width, uint32_t height) : width(width), height(height) {}
+
+  bool empty() const { return width == 0 || height == 0; }
+
+  operator bool() const { return !empty(); }
+
+  std::strong_ordering operator<=>(Size const& other) const {
+    if (empty()) {
+      return other.empty() ? std::strong_ordering::equal
+                           : std::strong_ordering::less;
+    }
+    if (other.empty())
+      return std::strong_ordering::greater;
+    auto ret = width <=> other.width;
+    return ret == std::strong_ordering::equal ? height <=> other.height : ret;
+  }
+
+  uint32_t width;
+  uint32_t height;
+};
+
+#endif  // SIZE_HH
diff --git a/src/spawner.cc b/src/spawner.cc
new file mode 100644
index 0000000..e49ac34
--- /dev/null
+++ b/src/spawner.cc
@@ -0,0 +1,236 @@
+#include "spawner.hh"
+
+#include "image_processor.hh"
+#include "io.hh"
+#include "unique_fd.hh"
+
+#include <cassert>
+#include <csignal>
+#include <expected>
+#include <linux/prctl.h>
+#include <memory>
+#include <sys/prctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <utility>
+
+namespace {
+
+int pidfd_getfd(int pidfd, int targetfd, unsigned int flags) {
+  return static_cast<int>(syscall(SYS_pidfd_getfd, pidfd, targetfd, flags));
+}
+
+// NOLINTNEXTLINE(misc-include-cleaner)
+int pidfd_open(pid_t pid, unsigned int flags) {
+  return static_cast<int>(syscall(SYS_pidfd_open, pid, flags));
+}
+
+class ProcessImpl : public Process {
+ public:
+  ProcessImpl(
+      pid_t pid,
+      std::pair<std::unique_ptr<io::Reader>, std::unique_ptr<io::Writer>> pipe)
+      : pid_(pid), pipe_(std::move(pipe)) {
+    assert(pid_);
+  }
+
+  [[nodiscard]]
+  pid_t pid() const { return pid_; }
+
+  [[nodiscard]]
+  io::Reader& reader() const override { return *pipe_.first; }
+
+  [[nodiscard]]
+  io::Writer& writer() const override { return *pipe_.second; }
+
+  void kill() {
+    if (pid_ != 0) {
+      ::kill(pid_, SIGTERM); // NOLINT(misc-include-cleaner)
+      pid_ = 0;
+    }
+  }
+
+ private:
+  pid_t pid_;
+  std::pair<std::unique_ptr<io::Reader>, std::unique_ptr<io::Writer>> pipe_;
+};
+
+struct Request {
+  Spawner::Exec exec;
+  int reader;
+  int writer;
+};
+
+struct Response {
+  pid_t pid;
+};
+
+void spawner_runner(unique_fd parent, std::unique_ptr<io::Reader> reader,
+                    std::unique_ptr<io::Writer> writer) {
+  while (true) {
+    Request request;
+    {
+      auto ret = reader->repeat_read(&request, sizeof(request));
+      if (!ret.has_value() || ret.value() != sizeof(request)) {
+        break;
+      }
+    }
+
+    // Need to not return a response before child has duped fds.
+    // So use a short-lived pipe to sync child start.
+    auto sync_pipe = io::pipe();
+    pid_t child_pid = 0;
+
+    if (sync_pipe.has_value()) {
+      child_pid = fork();
+      if (child_pid == 0) {
+        // Child process
+        sync_pipe->first.reset();
+        reader.reset();
+        writer.reset();
+
+        unique_fd child_reader_fd{pidfd_getfd(parent.get(), request.reader, 0)};
+        unique_fd child_writer_fd{pidfd_getfd(parent.get(), request.writer, 0)};
+
+        parent.reset();
+
+        if (child_reader_fd && child_writer_fd) {
+          char c = 1;
+          if (sync_pipe->second->write(&c, sizeof(c)).has_value()) {
+            auto child_reader = io::reader_from_raw(child_reader_fd.release());
+            auto child_writer = io::writer_from_raw(child_writer_fd.release());
+
+            switch (request.exec) {
+              case Spawner::Exec::kImageProcessor:
+                _exit(image_processor::run(std::move(child_reader),
+                                           std::move(child_writer)));
+            }
+          }
+        }
+
+        _exit(1);
+        // _exit obviously never returns but to help tools and compilers…
+        return;
+      }
+
+      // Parent process
+      if (child_pid == -1) {
+        // fork() failed, we use zero as error value.
+        child_pid = 0;
+      } else {
+        sync_pipe->second.reset();
+
+        char c = 1;
+        std::ignore = sync_pipe->first->read(&c, sizeof(c));
+      }
+    }
+
+    Response response{child_pid};
+    {
+      auto ret = writer->repeat_write(&response, sizeof(response));
+      if (!ret.has_value() || ret.value() != sizeof(response)) {
+        break;
+      }
+    }
+  }
+}
+
+class SpawnerImpl : public Spawner {
+ public:
+  explicit SpawnerImpl(std::unique_ptr<ProcessImpl> process)
+      : process_(std::move(process)) {}
+
+  ~SpawnerImpl() override {
+    if (process_) {
+      process_->kill();
+    }
+  }
+
+  [[nodiscard]]
+  std::expected<std::unique_ptr<Process>, Error> run(Exec exec) override {
+    if (!process_) {
+      return std::unexpected(Error::kError);
+    }
+
+    auto reader_pipe = io::pipe();
+    auto writer_pipe = io::pipe();
+    if (!reader_pipe.has_value() || !writer_pipe.has_value()) {
+      return std::unexpected(Error::kError);
+    }
+
+    Request req{
+      .exec = exec,
+      .reader = writer_pipe->first->raw_fd(),
+      .writer = reader_pipe->second->raw_fd(),
+    };
+    {
+      auto ret = process_->writer().repeat_write(&req, sizeof(req));
+      if (!ret.has_value() || ret.value() != sizeof(req)) {
+        process_->kill();
+        process_.reset();
+        return std::unexpected(Error::kError);
+      }
+    }
+
+    Response resp;
+    {
+      auto ret = process_->reader().repeat_read(&resp, sizeof(resp));
+      if (!ret.has_value() || ret.value() != sizeof(resp)) {
+        process_->kill();
+        process_.reset();
+        return std::unexpected(Error::kError);
+      }
+    }
+
+    if (resp.pid == 0)
+      return std::unexpected(Error::kError);
+
+    return std::make_unique<ProcessImpl>(
+        resp.pid, std::make_pair(std::move(reader_pipe->first),
+                                 std::move(writer_pipe->second)));
+  }
+
+ private:
+  std::unique_ptr<ProcessImpl> process_;
+};
+
+}  // namespace
+
+std::expected<std::unique_ptr<Spawner>, Spawner::Error> Spawner::create() {
+  auto reader_pipe = io::pipe();
+  auto writer_pipe = io::pipe();
+  if (!reader_pipe.has_value() || !writer_pipe.has_value()) {
+    return std::unexpected(Error::kError);
+  }
+
+  auto pid = getpid();
+  unique_fd pidfd{pidfd_open(pid, 0)};
+  if (!pidfd) {
+    return std::unexpected(Error::kError);
+  }
+
+  // Needed for pidfd_getfd to work in child.
+  if (prctl(PR_SET_PTRACER, pid) != 0) {
+    return std::unexpected(Error::kError);
+  }
+
+  pid = fork();
+  if (pid == 0) {
+    // Child process
+    reader_pipe->first.reset();
+    writer_pipe->second.reset();
+
+    spawner_runner(std::move(pidfd), std::move(writer_pipe->first),
+                   std::move(reader_pipe->second));
+    _exit(0);
+  }
+
+  // Parent process
+  if (pid == -1) {
+    return std::unexpected(Error::kError);
+  }
+
+  return std::make_unique<SpawnerImpl>(std::make_unique<ProcessImpl>(
+      pid, std::make_pair(std::move(reader_pipe->first),
+                          std::move(writer_pipe->second))));
+}
diff --git a/src/spawner.hh b/src/spawner.hh
new file mode 100644
index 0000000..c4f511b
--- /dev/null
+++ b/src/spawner.hh
@@ -0,0 +1,49 @@
+#ifndef SPAWNER_HH
+#define SPAWNER_HH
+
+#include <cstdint>
+#include <expected>
+#include <memory>
+
+namespace io {
+class Reader;
+class Writer;
+};  // namespace io
+
+class Process {
+ public:
+  virtual ~Process() = default;
+
+  virtual io::Reader& reader() const = 0;
+  virtual io::Writer& writer() const = 0;
+
+ protected:
+  Process() = default;
+  Process(Process const&) = delete;
+  Process& operator=(Process const&) = delete;
+};
+
+class Spawner {
+ public:
+  enum class Exec : uint8_t {
+    kImageProcessor,
+  };
+
+  enum class Error : uint8_t {
+    kError,
+  };
+
+  virtual ~Spawner() = default;
+
+  [[nodiscard]]
+  virtual std::expected<std::unique_ptr<Process>, Error> run(Exec exec) = 0;
+
+  static std::expected<std::unique_ptr<Spawner>, Error> create();
+
+ protected:
+  Spawner() = default;
+  Spawner(Spawner const&) = delete;
+  Spawner& operator=(Spawner const&) = delete;
+};
+
+#endif  // SPAWNER_HH
diff --git a/src/str.cc b/src/str.cc
new file mode 100644
index 0000000..129e0f3
--- /dev/null
+++ b/src/str.cc
@@ -0,0 +1,94 @@
+#include "str.hh"
+
+#include <cstddef>
+#include <string_view>
+#include <vector>
+
+namespace str {
+
+namespace {
+
+[[nodiscard]]
+inline bool is_space(char c) {
+  return c == ' ' || c == '\t' || c == '\r' || c == '\n';
+}
+
+}  // namespace
+
+void split(std::string_view str, std::vector<std::string_view>& out,
+           char separator, bool keep_empty) {
+  out.clear();
+
+  size_t offset = 0;
+  while (true) {
+    auto next = str.find(separator, offset);
+    if (next == std::string_view::npos) {
+      if (keep_empty || offset < str.size())
+        out.push_back(str.substr(offset));
+      break;
+    }
+    if (keep_empty || offset < next)
+      out.push_back(str.substr(offset, next - offset));
+    offset = next + 1;
+  }
+}
+
+std::vector<std::string_view> split(std::string_view str, char separator,
+                                    bool keep_empty) {
+  std::vector<std::string_view> vec;
+  split(str, vec, separator, keep_empty);
+  return vec;
+}
+
+void split(std::string_view str, std::vector<std::string_view>& out,
+           std::string_view separator, bool keep_empty) {
+  out.clear();
+
+  size_t offset = 0;
+  while (true) {
+    auto next = str.find(separator, offset);
+    if (next == std::string_view::npos) {
+      if (keep_empty || offset < str.size())
+        out.push_back(str.substr(offset));
+      break;
+    }
+    if (keep_empty || offset < next)
+      out.push_back(str.substr(offset, next - offset));
+    offset = next + separator.size();
+  }
+}
+
+std::vector<std::string_view> split(std::string_view str,
+                                    std::string_view separator,
+                                    bool keep_empty) {
+  std::vector<std::string_view> vec;
+  split(str, vec, separator, keep_empty);
+  return vec;
+}
+
+std::string_view trim(std::string_view str) {
+  size_t s = 0;
+  size_t e = str.size();
+  while (s < e && is_space(str[s]))
+    ++s;
+  while (e > s && is_space(str[e - 1]))
+    --e;
+  return str.substr(s, e - s);
+}
+
+std::string_view ltrim(std::string_view str) {
+  size_t s = 0;
+  size_t const e = str.size();
+  while (s < e && is_space(str[s]))
+    ++s;
+  return str.substr(s, e - s);
+}
+
+std::string_view rtrim(std::string_view str) {
+  size_t e = str.size();
+  while (e > 0 && is_space(str[e - 1]))
+    --e;
+  return str.substr(0, e);
+}
+
+}  // namespace str
diff --git a/src/str.hh b/src/str.hh
new file mode 100644
index 0000000..c736f4b
--- /dev/null
+++ b/src/str.hh
@@ -0,0 +1,34 @@
+#ifndef STR_HH
+#define STR_HH
+
+#include <string_view>
+#include <vector>
+
+namespace str {
+
+void split(std::string_view str, std::vector<std::string_view>& out,
+           char separator = ' ', bool keep_empty = false);
+
+[[nodiscard]] std::vector<std::string_view> split(std::string_view str,
+                                                  char separator = ' ',
+                                                  bool keep_empty = false);
+
+void split(std::string_view str, std::vector<std::string_view>& out,
+           std::string_view separator, bool keep_empty = false);
+
+[[nodiscard]] std::vector<std::string_view> split(std::string_view str,
+                                                  std::string_view separator,
+                                                  bool keep_empty = false);
+
+[[nodiscard]]
+std::string_view trim(std::string_view str);
+
+[[nodiscard]]
+std::string_view ltrim(std::string_view str);
+
+[[nodiscard]]
+std::string_view rtrim(std::string_view str);
+
+}  // namespace str
+
+#endif  // STR_HH
diff --git a/src/u.hh b/src/u.hh
new file mode 100644
index 0000000..439d6dc
--- /dev/null
+++ b/src/u.hh
@@ -0,0 +1,21 @@
+#ifndef U_HH
+#define U_HH
+
+#include <cstdint>
+
+namespace u {
+
+enum class ReadError : uint8_t {
+  Invalid,     // Invalid sequence
+  End,         // At end (it == end)
+  Incomplete,  // Too few bytes
+};
+
+enum class ReadErrorReplace : uint8_t {
+  End,         // At end (it == end)
+  Incomplete,  // Too few bytes
+};
+
+}  // namespace u
+
+#endif  // U_HH
diff --git a/src/u8.hh b/src/u8.hh
new file mode 100644
index 0000000..d673caa
--- /dev/null
+++ b/src/u8.hh
@@ -0,0 +1,196 @@
+#ifndef U8_HH
+#define U8_HH
+
+#include "u.hh"  // IWYU pragma: export
+
+#include <cstdint>  // IWYU pragma: export
+#include <expected>
+#include <iterator>
+#include <type_traits>
+#include <utility>
+
+namespace u8 {
+
+template <std::forward_iterator T>
+  requires std::is_same_v<std::iter_value_t<T>, uint8_t>
+std::expected<uint32_t, u::ReadError> read(T& start, T const& end) {
+  if (start == end)
+    return std::unexpected(u::ReadError::End);
+  uint32_t u;
+  switch (*start >> 4) {
+    case 0xf:
+      // 11110uvv 10vvwwww 10xxxxyy 10yyzzzz
+      if (std::distance(start, end) < 4) {
+        return std::unexpected(u::ReadError::Incomplete);
+      }
+      u = (*start & 0x07) << 18;
+      std::advance(start, 1);
+      if ((*start & 0xc0) != 0x80) {
+        std::advance(start, 3);
+        return std::unexpected(u::ReadError::Invalid);
+      }
+      u |= (*start & 0x3f) << 12;
+      std::advance(start, 1);
+      if ((*start & 0xc0) != 0x80) {
+        std::advance(start, 2);
+        return std::unexpected(u::ReadError::Invalid);
+      }
+      u |= (*start & 0x3f) << 6;
+      std::advance(start, 1);
+      if ((*start & 0xc0) != 0x80) {
+        std::advance(start, 1);
+        return std::unexpected(u::ReadError::Invalid);
+      }
+      u |= *start & 0x3f;
+      if (u < 0x10000 || u > 0x10ffff) {
+        std::advance(start, 1);
+        return std::unexpected(u::ReadError::Invalid);
+      }
+      break;
+    case 0xe:
+      // 1110wwww 10xxxxyy 10yyzzzz
+      if (std::distance(start, end) < 3) {
+        return std::unexpected(u::ReadError::Incomplete);
+      }
+      u = (*start & 0x0f) << 12;
+      std::advance(start, 1);
+      if ((*start & 0xc0) != 0x80) {
+        std::advance(start, 2);
+        return std::unexpected(u::ReadError::Invalid);
+      }
+      u |= (*start & 0x3f) << 6;
+      std::advance(start, 1);
+      if ((*start & 0xc0) != 0x80) {
+        std::advance(start, 1);
+        return std::unexpected(u::ReadError::Invalid);
+      }
+      u |= *start & 0x3f;
+      if (u < 0x800 || (u >= 0xd800 && u <= 0xdfff)) {
+        std::advance(start, 1);
+        return std::unexpected(u::ReadError::Invalid);
+      }
+      break;
+    case 0xd:
+    case 0xc:
+      // 110xxxyy 10yyzzzz
+      if (std::distance(start, end) < 2) {
+        return std::unexpected(u::ReadError::Incomplete);
+      }
+      u = (*start & 0x1f) << 6;
+      std::advance(start, 1);
+      if ((*start & 0xc0) != 0x80) {
+        std::advance(start, 1);
+        return std::unexpected(u::ReadError::Invalid);
+      }
+      u |= *start & 0x3f;
+      if (u < 0x80) {
+        std::advance(start, 1);
+        return std::unexpected(u::ReadError::Invalid);
+      }
+      break;
+    case 0xb:
+    case 0xa:
+    case 0x9:
+    case 0x8:
+      std::advance(start, 1);
+      return std::unexpected(u::ReadError::Invalid);
+    default:
+      // 0yyyzzzz
+      u = *start;
+      break;
+  }
+  std::advance(start, 1);
+  return u;
+}
+
+template <std::forward_iterator T>
+  requires std::is_same_v<std::iter_value_t<T>, uint8_t>
+std::expected<uint32_t, u::ReadErrorReplace> read_replace(T& start,
+                                                          T const& end,
+                                                          bool eof) {
+  auto const tmp = start;
+  auto ret = read(start, end);
+  if (ret.has_value())
+    return *ret;
+  switch (ret.error()) {
+    case u::ReadError::Incomplete:
+      if (eof)
+        break;
+      return std::unexpected(u::ReadErrorReplace::Incomplete);
+    case u::ReadError::End:
+      return std::unexpected(u::ReadErrorReplace::End);
+    case u::ReadError::Invalid:
+      break;
+  }
+  start = tmp + 1;
+  return 0xfffd;
+}
+
+template <std::forward_iterator T>
+  requires std::is_same_v<std::iter_value_t<T>, uint8_t>
+bool write(T& start, T const& end, uint32_t code) {
+  if (code < 0x80) {
+    if (start == end)
+      return false;
+    *start = static_cast<uint8_t>(code);
+  } else if (code < 0x800) {
+    if (std::distance(start, end) < 2)
+      return false;
+    *start = 0xc0 | static_cast<uint8_t>(code >> 6);
+    std::advance(start, 1);
+    *start = 0x80 | static_cast<uint8_t>(code & 0x3f);
+  } else if (code < 0x10000) {
+    if (std::distance(start, end) < 3)
+      return false;
+    *start = 0xe0 | static_cast<uint8_t>(code >> 12);
+    std::advance(start, 1);
+    *start = 0x80 | static_cast<uint8_t>((code >> 6) & 0x3f);
+    std::advance(start, 1);
+    *start = 0x80 | static_cast<uint8_t>(code & 0x3f);
+  } else {
+    if (std::distance(start, end) < 4)
+      return false;
+    *start = 0xf0 | static_cast<uint8_t>(code >> 18);
+    std::advance(start, 1);
+    *start = 0x80 | static_cast<uint8_t>((code >> 12) & 0x3f);
+    std::advance(start, 1);
+    *start = 0x80 | static_cast<uint8_t>((code >> 6) & 0x3f);
+    std::advance(start, 1);
+    *start = 0x80 | static_cast<uint8_t>(code & 0x3f);
+  }
+  std::advance(start, 1);
+  return true;
+}
+
+template <std::forward_iterator T>
+  requires std::is_same_v<std::iter_value_t<T>, uint8_t>
+bool skip(T& start, T const& end) {
+  if (start == end)
+    return false;
+  switch (*start >> 4) {
+    case 0xf:
+      if (std::distance(start, end) < 4)
+        return false;
+      std::advance(start, 4);
+      break;
+    case 0xe:
+      if (std::distance(start, end) < 3)
+        return false;
+      std::advance(start, 3);
+      break;
+    case 0xc:
+    case 0xd:
+      if (std::distance(start, end) < 2)
+        return false;
+      std::advance(start, 2);
+      break;
+    default:
+      std::advance(start, 1);
+      break;
+  }
+  return true;
+}
+
+}  // namespace u8
+
+#endif  // U8_HH
diff --git a/src/unique_fd.cc b/src/unique_fd.cc
new file mode 100644
index 0000000..135a449
--- /dev/null
+++ b/src/unique_fd.cc
@@ -0,0 +1,9 @@
+#include "unique_fd.hh"
+
+#include <unistd.h>
+
+void unique_fd::reset(int fd) {
+  if (fd_ != -1)
+    close(fd_);
+  fd_ = fd;
+}
diff --git a/src/unique_fd.hh b/src/unique_fd.hh
new file mode 100644
index 0000000..2950905
--- /dev/null
+++ b/src/unique_fd.hh
@@ -0,0 +1,36 @@
+#ifndef UNIQUE_FD_HH
+#define UNIQUE_FD_HH
+
+class unique_fd {
+ public:
+  constexpr unique_fd() : fd_(-1) {}
+  explicit constexpr unique_fd(int fd) : fd_(fd) {}
+  unique_fd(unique_fd& fd) = delete;
+  unique_fd& operator=(unique_fd& fd) = delete;
+  unique_fd(unique_fd&& fd) : fd_(fd.release()) {}
+  unique_fd& operator=(unique_fd&& fd) {
+    reset(fd.release());
+    return *this;
+  }
+  ~unique_fd() { reset(); }
+
+  bool operator==(unique_fd const& fd) const { return get() == fd.get(); }
+  bool operator!=(unique_fd const& fd) const { return get() != fd.get(); }
+
+  int get() const { return fd_; }
+  explicit operator bool() const { return fd_ != -1; }
+  int operator*() const { return fd_; }
+
+  int release() {
+    int ret = fd_;
+    fd_ = -1;
+    return ret;
+  }
+
+  void reset(int fd = -1);
+
+ private:
+  int fd_;
+};
+
+#endif  // UNIQUE_FD_HH
diff --git a/src/xpm/.clang-tidy b/src/xpm/.clang-tidy
new file mode 100644
index 0000000..8f60b95
--- /dev/null
+++ b/src/xpm/.clang-tidy
@@ -0,0 +1,2 @@
+---
+Checks: ''
diff --git a/src/xpm/color.c b/src/xpm/color.c
new file mode 100644
index 0000000..ead7073
--- /dev/null
+++ b/src/xpm/color.c
@@ -0,0 +1,882 @@
+/***********************************************************
+
+Copyright 1987, 1998  The Open Group
+
+Permission to use, copy, modify, distribute, and sell this software and its
+documentation for any purpose is hereby granted without fee, provided that
+the above copyright notice appear in all copies and that both that
+copyright notice and this permission notice appear in supporting
+documentation.
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of The Open Group shall not be
+used in advertising or otherwise to promote the sale, use or other dealings
+in this Software without prior written authorization from The Open Group.
+
+Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts.
+
+                        All Rights Reserved
+
+Permission to use, copy, modify, and distribute this software and its
+documentation for any purpose and without fee is hereby granted,
+provided that the above copyright notice appear in all copies and that
+both that copyright notice and this permission notice appear in
+supporting documentation, and that the name of Digital not be
+used in advertising or publicity pertaining to distribution of the
+software without specific, written prior permission.
+
+DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
+ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
+DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
+ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+SOFTWARE.
+
+******************************************************************/
+
+#include <dix-config.h>
+
+#include <X11/keysym.h>
+
+#include "dix/dix_priv.h"
+#include "include/dix.h"
+
+typedef struct _builtinColor {
+    unsigned char red;
+    unsigned char green;
+    unsigned char blue;
+    const char *name;
+} BuiltinColor;
+
+static const BuiltinColor BuiltinColors[] = {
+/*    R    G    B     name                  */
+    { 240, 248, 255, "alice blue"             },
+    { 240, 248, 255, "AliceBlue"              },
+    { 250, 235, 215, "antique white"          },
+    { 250, 235, 215, "AntiqueWhite"           },
+    { 255, 239, 219, "AntiqueWhite1"          },
+    { 238, 223, 204, "AntiqueWhite2"          },
+    { 205, 192, 176, "AntiqueWhite3"          },
+    { 139, 131, 120, "AntiqueWhite4"          },
+    {   0, 255, 255, "aqua"                   },
+    { 127, 255, 212, "aquamarine"             },
+    { 127, 255, 212, "aquamarine1"            },
+    { 118, 238, 198, "aquamarine2"            },
+    { 102, 205, 170, "aquamarine3"            },
+    {  69, 139, 116, "aquamarine4"            },
+    { 240, 255, 255, "azure"                  },
+    { 240, 255, 255, "azure1"                 },
+    { 224, 238, 238, "azure2"                 },
+    { 193, 205, 205, "azure3"                 },
+    { 131, 139, 139, "azure4"                 },
+    { 245, 245, 220, "beige"                  },
+    { 255, 228, 196, "bisque"                 },
+    { 255, 228, 196, "bisque1"                },
+    { 238, 213, 183, "bisque2"                },
+    { 205, 183, 158, "bisque3"                },
+    { 139, 125, 107, "bisque4"                },
+    {   0,   0,   0, "black"                  },
+    { 255, 235, 205, "blanched almond"        },
+    { 255, 235, 205, "BlanchedAlmond"         },
+    {   0,   0, 255, "blue"                   },
+    { 138,  43, 226, "blue violet"            },
+    {   0,   0, 255, "blue1"                  },
+    {   0,   0, 238, "blue2"                  },
+    {   0,   0, 205, "blue3"                  },
+    {   0,   0, 139, "blue4"                  },
+    { 138,  43, 226, "BlueViolet"             },
+    { 165,  42,  42, "brown"                  },
+    { 255,  64,  64, "brown1"                 },
+    { 238,  59,  59, "brown2"                 },
+    { 205,  51,  51, "brown3"                 },
+    { 139,  35,  35, "brown4"                 },
+    { 222, 184, 135, "burlywood"              },
+    { 255, 211, 155, "burlywood1"             },
+    { 238, 197, 145, "burlywood2"             },
+    { 205, 170, 125, "burlywood3"             },
+    { 139, 115,  85, "burlywood4"             },
+    {  95, 158, 160, "cadet blue"             },
+    {  95, 158, 160, "CadetBlue"              },
+    { 152, 245, 255, "CadetBlue1"             },
+    { 142, 229, 238, "CadetBlue2"             },
+    { 122, 197, 205, "CadetBlue3"             },
+    {  83, 134, 139, "CadetBlue4"             },
+    { 127, 255,   0, "chartreuse"             },
+    { 127, 255,   0, "chartreuse1"            },
+    { 118, 238,   0, "chartreuse2"            },
+    { 102, 205,   0, "chartreuse3"            },
+    {  69, 139,   0, "chartreuse4"            },
+    { 210, 105,  30, "chocolate"              },
+    { 255, 127,  36, "chocolate1"             },
+    { 238, 118,  33, "chocolate2"             },
+    { 205, 102,  29, "chocolate3"             },
+    { 139,  69,  19, "chocolate4"             },
+    { 255, 127,  80, "coral"                  },
+    { 255, 114,  86, "coral1"                 },
+    { 238, 106,  80, "coral2"                 },
+    { 205,  91,  69, "coral3"                 },
+    { 139,  62,  47, "coral4"                 },
+    { 100, 149, 237, "cornflower blue"        },
+    { 100, 149, 237, "CornflowerBlue"         },
+    { 255, 248, 220, "cornsilk"               },
+    { 255, 248, 220, "cornsilk1"              },
+    { 238, 232, 205, "cornsilk2"              },
+    { 205, 200, 177, "cornsilk3"              },
+    { 139, 136, 120, "cornsilk4"              },
+    { 220,  20,  60, "crimson"                },
+    {   0, 255, 255, "cyan"                   },
+    {   0, 255, 255, "cyan1"                  },
+    {   0, 238, 238, "cyan2"                  },
+    {   0, 205, 205, "cyan3"                  },
+    {   0, 139, 139, "cyan4"                  },
+    {   0,   0, 139, "dark blue"              },
+    {   0, 139, 139, "dark cyan"              },
+    { 184, 134,  11, "dark goldenrod"         },
+    { 169, 169, 169, "dark gray"              },
+    {   0, 100,   0, "dark green"             },
+    { 169, 169, 169, "dark grey"              },
+    { 189, 183, 107, "dark khaki"             },
+    { 139,   0, 139, "dark magenta"           },
+    {  85, 107,  47, "dark olive green"       },
+    { 255, 140,   0, "dark orange"            },
+    { 153,  50, 204, "dark orchid"            },
+    { 139,   0,   0, "dark red"               },
+    { 233, 150, 122, "dark salmon"            },
+    { 143, 188, 143, "dark sea green"         },
+    {  72,  61, 139, "dark slate blue"        },
+    {  47,  79,  79, "dark slate gray"        },
+    {  47,  79,  79, "dark slate grey"        },
+    {   0, 206, 209, "dark turquoise"         },
+    { 148,   0, 211, "dark violet"            },
+    {   0,   0, 139, "DarkBlue"               },
+    {   0, 139, 139, "DarkCyan"               },
+    { 184, 134,  11, "DarkGoldenrod"          },
+    { 255, 185,  15, "DarkGoldenrod1"         },
+    { 238, 173,  14, "DarkGoldenrod2"         },
+    { 205, 149,  12, "DarkGoldenrod3"         },
+    { 139, 101,   8, "DarkGoldenrod4"         },
+    { 169, 169, 169, "DarkGray"               },
+    {   0, 100,   0, "DarkGreen"              },
+    { 169, 169, 169, "DarkGrey"               },
+    { 189, 183, 107, "DarkKhaki"              },
+    { 139,   0, 139, "DarkMagenta"            },
+    {  85, 107,  47, "DarkOliveGreen"         },
+    { 202, 255, 112, "DarkOliveGreen1"        },
+    { 188, 238, 104, "DarkOliveGreen2"        },
+    { 162, 205,  90, "DarkOliveGreen3"        },
+    { 110, 139,  61, "DarkOliveGreen4"        },
+    { 255, 140,   0, "DarkOrange"             },
+    { 255, 127,   0, "DarkOrange1"            },
+    { 238, 118,   0, "DarkOrange2"            },
+    { 205, 102,   0, "DarkOrange3"            },
+    { 139,  69,   0, "DarkOrange4"            },
+    { 153,  50, 204, "DarkOrchid"             },
+    { 191,  62, 255, "DarkOrchid1"            },
+    { 178,  58, 238, "DarkOrchid2"            },
+    { 154,  50, 205, "DarkOrchid3"            },
+    { 104,  34, 139, "DarkOrchid4"            },
+    { 139,   0,   0, "DarkRed"                },
+    { 233, 150, 122, "DarkSalmon"             },
+    { 143, 188, 143, "DarkSeaGreen"           },
+    { 193, 255, 193, "DarkSeaGreen1"          },
+    { 180, 238, 180, "DarkSeaGreen2"          },
+    { 155, 205, 155, "DarkSeaGreen3"          },
+    { 105, 139, 105, "DarkSeaGreen4"          },
+    {  72,  61, 139, "DarkSlateBlue"          },
+    {  47,  79,  79, "DarkSlateGray"          },
+    { 151, 255, 255, "DarkSlateGray1"         },
+    { 141, 238, 238, "DarkSlateGray2"         },
+    { 121, 205, 205, "DarkSlateGray3"         },
+    {  82, 139, 139, "DarkSlateGray4"         },
+    {  47,  79,  79, "DarkSlateGrey"          },
+    {   0, 206, 209, "DarkTurquoise"          },
+    { 148,   0, 211, "DarkViolet"             },
+    { 255,  20, 147, "deep pink"              },
+    {   0, 191, 255, "deep sky blue"          },
+    { 255,  20, 147, "DeepPink"               },
+    { 255,  20, 147, "DeepPink1"              },
+    { 238,  18, 137, "DeepPink2"              },
+    { 205,  16, 118, "DeepPink3"              },
+    { 139,  10,  80, "DeepPink4"              },
+    {   0, 191, 255, "DeepSkyBlue"            },
+    {   0, 191, 255, "DeepSkyBlue1"           },
+    {   0, 178, 238, "DeepSkyBlue2"           },
+    {   0, 154, 205, "DeepSkyBlue3"           },
+    {   0, 104, 139, "DeepSkyBlue4"           },
+    { 105, 105, 105, "dim gray"               },
+    { 105, 105, 105, "dim grey"               },
+    { 105, 105, 105, "DimGray"                },
+    { 105, 105, 105, "DimGrey"                },
+    {  30, 144, 255, "dodger blue"            },
+    {  30, 144, 255, "DodgerBlue"             },
+    {  30, 144, 255, "DodgerBlue1"            },
+    {  28, 134, 238, "DodgerBlue2"            },
+    {  24, 116, 205, "DodgerBlue3"            },
+    {  16,  78, 139, "DodgerBlue4"            },
+    { 178,  34,  34, "firebrick"              },
+    { 255,  48,  48, "firebrick1"             },
+    { 238,  44,  44, "firebrick2"             },
+    { 205,  38,  38, "firebrick3"             },
+    { 139,  26,  26, "firebrick4"             },
+    { 255, 250, 240, "floral white"           },
+    { 255, 250, 240, "FloralWhite"            },
+    {  34, 139,  34, "forest green"           },
+    {  34, 139,  34, "ForestGreen"            },
+    { 255,   0, 255, "fuchsia"                },
+    { 220, 220, 220, "gainsboro"              },
+    { 248, 248, 255, "ghost white"            },
+    { 248, 248, 255, "GhostWhite"             },
+    { 255, 215,   0, "gold"                   },
+    { 255, 215,   0, "gold1"                  },
+    { 238, 201,   0, "gold2"                  },
+    { 205, 173,   0, "gold3"                  },
+    { 139, 117,   0, "gold4"                  },
+    { 218, 165,  32, "goldenrod"              },
+    { 255, 193,  37, "goldenrod1"             },
+    { 238, 180,  34, "goldenrod2"             },
+    { 205, 155,  29, "goldenrod3"             },
+    { 139, 105,  20, "goldenrod4"             },
+    { 190, 190, 190, "gray"                   },
+    {   0,   0,   0, "gray0"                  },
+    {   3,   3,   3, "gray1"                  },
+    {  26,   26, 26, "gray10"                 },
+    { 255, 255, 255, "gray100"                },
+    {  28,  28,  28, "gray11"                 },
+    {  31,  31,  31, "gray12"                 },
+    {  33,  33,  33, "gray13"                 },
+    {  36,  36,  36, "gray14"                 },
+    {  38,  38,  38, "gray15"                 },
+    {  41,  41,  41, "gray16"                 },
+    {  43,  43,  43, "gray17"                 },
+    {  46,  46,  46, "gray18"                 },
+    {  48,  48,  48, "gray19"                 },
+    {   5,   5,   5, "gray2"                  },
+    {  51,  51,  51, "gray20"                 },
+    {  54,  54,  54, "gray21"                 },
+    {  56,  56,  56, "gray22"                 },
+    {  59,  59,  59, "gray23"                 },
+    {  61,  61,  61, "gray24"                 },
+    {  64,  64,  64, "gray25"                 },
+    {  66,  66,  66, "gray26"                 },
+    {  69,  69,  69, "gray27"                 },
+    {  71,  71,  71, "gray28"                 },
+    {  74,  74,  74, "gray29"                 },
+    {   8,   8,   8, "gray3"                  },
+    {  77,  77,  77, "gray30"                 },
+    {  79,  79,  79, "gray31"                 },
+    {  82,  82,  82, "gray32"                 },
+    {  84,  84,  84, "gray33"                 },
+    {  87,  87,  87, "gray34"                 },
+    {  89,  89,  89, "gray35"                 },
+    {  92,  92,  92, "gray36"                 },
+    {  94,  94,  94, "gray37"                 },
+    {  97,  97,  97, "gray38"                 },
+    {  99,  99,  99, "gray39"                 },
+    {  10,  10,  10, "gray4"                  },
+    { 102, 102, 102, "gray40"                 },
+    { 105, 105, 105, "gray41"                 },
+    { 107, 107, 107, "gray42"                 },
+    { 110, 110, 110, "gray43"                 },
+    { 112, 112, 112, "gray44"                 },
+    { 115, 115, 115, "gray45"                 },
+    { 117, 117, 117, "gray46"                 },
+    { 120, 120, 120, "gray47"                 },
+    { 122, 122, 122, "gray48"                 },
+    { 125, 125, 125, "gray49"                 },
+    {  13,  13,  13, "gray5"                  },
+    { 127, 127, 127, "gray50"                 },
+    { 130, 130, 130, "gray51"                 },
+    { 133, 133, 133, "gray52"                 },
+    { 135, 135, 135, "gray53"                 },
+    { 138, 138, 138, "gray54"                 },
+    { 140, 140, 140, "gray55"                 },
+    { 143, 143, 143, "gray56"                 },
+    { 145, 145, 145, "gray57"                 },
+    { 148, 148, 148, "gray58"                 },
+    { 150, 150, 150, "gray59"                 },
+    {  15,  15,  15, "gray6"                  },
+    { 153, 153, 153, "gray60"                 },
+    { 156, 156, 156, "gray61"                 },
+    { 158, 158, 158, "gray62"                 },
+    { 161, 161, 161, "gray63"                 },
+    { 163, 163, 163, "gray64"                 },
+    { 166, 166, 166, "gray65"                 },
+    { 168, 168, 168, "gray66"                 },
+    { 171, 171, 171, "gray67"                 },
+    { 173, 173, 173, "gray68"                 },
+    { 176, 176, 176, "gray69"                 },
+    {  18,  18,  18, "gray7"                  },
+    { 179, 179, 179, "gray70"                 },
+    { 181, 181, 181, "gray71"                 },
+    { 184, 184, 184, "gray72"                 },
+    { 186, 186, 186, "gray73"                 },
+    { 189, 189, 189, "gray74"                 },
+    { 191, 191, 191, "gray75"                 },
+    { 194, 194, 194, "gray76"                 },
+    { 196, 196, 196, "gray77"                 },
+    { 199, 199, 199, "gray78"                 },
+    { 201, 201, 201, "gray79"                 },
+    {  20,  20,  20, "gray8"                  },
+    { 204, 204, 204, "gray80"                 },
+    { 207, 207, 207, "gray81"                 },
+    { 209, 209, 209, "gray82"                 },
+    { 212, 212, 212, "gray83"                 },
+    { 214, 214, 214, "gray84"                 },
+    { 217, 217, 217, "gray85"                 },
+    { 219, 219, 219, "gray86"                 },
+    { 222, 222, 222, "gray87"                 },
+    { 224, 224, 224, "gray88"                 },
+    { 227, 227, 227, "gray89"                 },
+    {  23,  23,  23, "gray9"                  },
+    { 229, 229, 229, "gray90"                 },
+    { 232, 232, 232, "gray91"                 },
+    { 235, 235, 235, "gray92"                 },
+    { 237, 237, 237, "gray93"                 },
+    { 240, 240, 240, "gray94"                 },
+    { 242, 242, 242, "gray95"                 },
+    { 245, 245, 245, "gray96"                 },
+    { 247, 247, 247, "gray97"                 },
+    { 250, 250, 250, "gray98"                 },
+    { 252, 252, 252, "gray99"                 },
+    {   0, 255,   0, "green"                  },
+    { 173, 255,  47, "green yellow"           },
+    {   0, 255,   0, "green1"                 },
+    {   0, 238,   0, "green2"                 },
+    {   0, 205,   0, "green3"                 },
+    {   0, 139,   0, "green4"                 },
+    { 173, 255,  47, "GreenYellow"            },
+    { 190, 190, 190, "grey"                   },
+    {   0,   0,   0, "grey0"                  },
+    {   3,   3,   3, "grey1"                  },
+    {  26,  26,  26, "grey10"                 },
+    { 255, 255, 255, "grey100"                },
+    {  28,  28,  28, "grey11"                 },
+    {  31,  31,  31, "grey12"                 },
+    {  33,  33,  33, "grey13"                 },
+    {  36,  36,  36, "grey14"                 },
+    {  38,  38,  38, "grey15"                 },
+    {  41,  41,  41, "grey16"                 },
+    {  43,  43,  43, "grey17"                 },
+    {  46,  46,  46, "grey18"                 },
+    {  48,  48,  48, "grey19"                 },
+    {   5,   5,   5, "grey2"                  },
+    {  51,  51,  51, "grey20"                 },
+    {  54,  54,  54, "grey21"                 },
+    {  56,  56,  56, "grey22"                 },
+    {  59,  59,  59, "grey23"                 },
+    {  61,  61,  61, "grey24"                 },
+    {  64,  64,  64, "grey25"                 },
+    {  66,  66,  66, "grey26"                 },
+    {  69,  69,  69, "grey27"                 },
+    {  71,  71,  71, "grey28"                 },
+    {  74,  74,  74, "grey29"                 },
+    {   8,   8,   8, "grey3"                  },
+    {  77,  77,  77, "grey30"                 },
+    {  79,  79,  79, "grey31"                 },
+    {  82,  82,  82, "grey32"                 },
+    {  84,  84,  84, "grey33"                 },
+    {  87,  87,  87, "grey34"                 },
+    {  89,  89,  89, "grey35"                 },
+    {  92,  92,  92, "grey36"                 },
+    {  94,  94,  94, "grey37"                 },
+    {  97,  97,  97, "grey38"                 },
+    {  99,  99,  99, "grey39"                 },
+    {  10,  10,  10, "grey4"                  },
+    { 102, 102, 102, "grey40"                 },
+    { 105, 105, 105, "grey41"                 },
+    { 107, 107, 107, "grey42"                 },
+    { 110, 110, 110, "grey43"                 },
+    { 112, 112, 112, "grey44"                 },
+    { 115, 115, 115, "grey45"                 },
+    { 117, 117, 117, "grey46"                 },
+    { 120, 120, 120, "grey47"                 },
+    { 122, 122, 122, "grey48"                 },
+    { 125, 125, 125, "grey49"                 },
+    {  13,  13,  13, "grey5"                  },
+    { 127, 127, 127, "grey50"                 },
+    { 130, 130, 130, "grey51"                 },
+    { 133, 133, 133, "grey52"                 },
+    { 135, 135, 135, "grey53"                 },
+    { 138, 138, 138, "grey54"                 },
+    { 140, 140, 140, "grey55"                 },
+    { 143, 143, 143, "grey56"                 },
+    { 145, 145, 145, "grey57"                 },
+    { 148, 148, 148, "grey58"                 },
+    { 150, 150, 150, "grey59"                 },
+    {  15,  15,  15, "grey6"                  },
+    { 153, 153, 153, "grey60"                 },
+    { 156, 156, 156, "grey61"                 },
+    { 158, 158, 158, "grey62"                 },
+    { 161, 161, 161, "grey63"                 },
+    { 163, 163, 163, "grey64"                 },
+    { 166, 166, 166, "grey65"                 },
+    { 168, 168, 168, "grey66"                 },
+    { 171, 171, 171, "grey67"                 },
+    { 173, 173, 173, "grey68"                 },
+    { 176, 176, 176, "grey69"                 },
+    {  18,  18,  18, "grey7"                  },
+    { 179, 179, 179, "grey70"                 },
+    { 181, 181, 181, "grey71"                 },
+    { 184, 184, 184, "grey72"                 },
+    { 186, 186, 186, "grey73"                 },
+    { 189, 189, 189, "grey74"                 },
+    { 191, 191, 191, "grey75"                 },
+    { 194, 194, 194, "grey76"                 },
+    { 196, 196, 196, "grey77"                 },
+    { 199, 199, 199, "grey78"                 },
+    { 201, 201, 201, "grey79"                 },
+    {  20,  20,  20, "grey8"                  },
+    { 204, 204, 204, "grey80"                 },
+    { 207, 207, 207, "grey81"                 },
+    { 209, 209, 209, "grey82"                 },
+    { 212, 212, 212, "grey83"                 },
+    { 214, 214, 214, "grey84"                 },
+    { 217, 217, 217, "grey85"                 },
+    { 219, 219, 219, "grey86"                 },
+    { 222, 222, 222, "grey87"                 },
+    { 224, 224, 224, "grey88"                 },
+    { 227, 227, 227, "grey89"                 },
+    {  23,  23,  23, "grey9"                  },
+    { 229, 229, 229, "grey90"                 },
+    { 232, 232, 232, "grey91"                 },
+    { 235, 235, 235, "grey92"                 },
+    { 237, 237, 237, "grey93"                 },
+    { 240, 240, 240, "grey94"                 },
+    { 242, 242, 242, "grey95"                 },
+    { 245, 245, 245, "grey96"                 },
+    { 247, 247, 247, "grey97"                 },
+    { 250, 250, 250, "grey98"                 },
+    { 252, 252, 252, "grey99"                 },
+    { 240, 255, 240, "honeydew"               },
+    { 240, 255, 240, "honeydew1"              },
+    { 224, 238, 224, "honeydew2"              },
+    { 193, 205, 193, "honeydew3"              },
+    { 131, 139, 131, "honeydew4"              },
+    { 255, 105, 180, "hot pink"               },
+    { 255, 105, 180, "HotPink"                },
+    { 255, 110, 180, "HotPink1"               },
+    { 238, 106, 167, "HotPink2"               },
+    { 205,  96, 144, "HotPink3"               },
+    { 139,  58,  98, "HotPink4"               },
+    { 205,  92,  92, "indian red"             },
+    { 205,  92,  92, "IndianRed"              },
+    { 255, 106, 106, "IndianRed1"             },
+    { 238,  99,  99, "IndianRed2"             },
+    { 205,  85,  85, "IndianRed3"             },
+    { 139,  58,  58, "IndianRed4"             },
+    {  75,   0, 130, "indigo"                 },
+    { 255, 255, 240, "ivory"                  },
+    { 255, 255, 240, "ivory1"                 },
+    { 238, 238, 224, "ivory2"                 },
+    { 205, 205, 193, "ivory3"                 },
+    { 139, 139, 131, "ivory4"                 },
+    { 240, 230, 140, "khaki"                  },
+    { 255, 246, 143, "khaki1"                 },
+    { 238, 230, 133, "khaki2"                 },
+    { 205, 198, 115, "khaki3"                 },
+    { 139, 134,  78, "khaki4"                 },
+    { 230, 230, 250, "lavender"               },
+    { 255, 240, 245, "lavender blush"         },
+    { 255, 240, 245, "LavenderBlush"          },
+    { 255, 240, 245, "LavenderBlush1"         },
+    { 238, 224, 229, "LavenderBlush2"         },
+    { 205, 193, 197, "LavenderBlush3"         },
+    { 139, 131, 134, "LavenderBlush4"         },
+    { 124, 252,   0, "lawn green"             },
+    { 124, 252,   0, "LawnGreen"              },
+    { 255, 250, 205, "lemon chiffon"          },
+    { 255, 250, 205, "LemonChiffon"           },
+    { 255, 250, 205, "LemonChiffon1"          },
+    { 238, 233, 191, "LemonChiffon2"          },
+    { 205, 201, 165, "LemonChiffon3"          },
+    { 139, 137, 112, "LemonChiffon4"          },
+    { 173, 216, 230, "light blue"             },
+    { 240, 128, 128, "light coral"            },
+    { 224, 255, 255, "light cyan"             },
+    { 238, 221, 130, "light goldenrod"        },
+    { 250, 250, 210, "light goldenrod yellow" },
+    { 211, 211, 211, "light gray"             },
+    { 144, 238, 144, "light green"            },
+    { 211, 211, 211, "light grey"             },
+    { 255, 182, 193, "light pink"             },
+    { 255, 160, 122, "light salmon"           },
+    {  32, 178, 170, "light sea green"        },
+    { 135, 206, 250, "light sky blue"         },
+    { 132, 112, 255, "light slate blue"       },
+    { 119, 136, 153, "light slate gray"       },
+    { 119, 136, 153, "light slate grey"       },
+    { 176, 196, 222, "light steel blue"       },
+    { 255, 255, 224, "light yellow"           },
+    { 173, 216, 230, "LightBlue"              },
+    { 191, 239, 255, "LightBlue1"             },
+    { 178, 223, 238, "LightBlue2"             },
+    { 154, 192, 205, "LightBlue3"             },
+    { 104, 131, 139, "LightBlue4"             },
+    { 240, 128, 128, "LightCoral"             },
+    { 224, 255, 255, "LightCyan"              },
+    { 224, 255, 255, "LightCyan1"             },
+    { 209, 238, 238, "LightCyan2"             },
+    { 180, 205, 205, "LightCyan3"             },
+    { 122, 139, 139, "LightCyan4"             },
+    { 238, 221, 130, "LightGoldenrod"         },
+    { 255, 236, 139, "LightGoldenrod1"        },
+    { 238, 220, 130, "LightGoldenrod2"        },
+    { 205, 190, 112, "LightGoldenrod3"        },
+    { 139, 129,  76, "LightGoldenrod4"        },
+    { 250, 250, 210, "LightGoldenrodYellow"   },
+    { 211, 211, 211, "LightGray"              },
+    { 144, 238, 144, "LightGreen"             },
+    { 211, 211, 211, "LightGrey"              },
+    { 255, 182, 193, "LightPink"              },
+    { 255, 174, 185, "LightPink1"             },
+    { 238, 162, 173, "LightPink2"             },
+    { 205, 140, 149, "LightPink3"             },
+    { 139,  95, 101, "LightPink4"             },
+    { 255, 160, 122, "LightSalmon"            },
+    { 255, 160, 122, "LightSalmon1"           },
+    { 238, 149, 114, "LightSalmon2"           },
+    { 205, 129,  98, "LightSalmon3"           },
+    { 139,  87,  66, "LightSalmon4"           },
+    {  32, 178, 170, "LightSeaGreen"          },
+    { 135, 206, 250, "LightSkyBlue"           },
+    { 176, 226, 255, "LightSkyBlue1"          },
+    { 164, 211, 238, "LightSkyBlue2"          },
+    { 141, 182, 205, "LightSkyBlue3"          },
+    {  96, 123, 139, "LightSkyBlue4"          },
+    { 132, 112, 255, "LightSlateBlue"         },
+    { 119, 136, 153, "LightSlateGray"         },
+    { 119, 136, 153, "LightSlateGrey"         },
+    { 176, 196, 222, "LightSteelBlue"         },
+    { 202, 225, 255, "LightSteelBlue1"        },
+    { 188, 210, 238, "LightSteelBlue2"        },
+    { 162, 181, 205, "LightSteelBlue3"        },
+    { 110, 123, 139, "LightSteelBlue4"        },
+    { 255, 255, 224, "LightYellow"            },
+    { 255, 255, 224, "LightYellow1"           },
+    { 238, 238, 209, "LightYellow2"           },
+    { 205, 205, 180, "LightYellow3"           },
+    { 139, 139, 122, "LightYellow4"           },
+    {   0, 255,   0, "lime"                   },
+    {  50, 205,  50, "lime green"             },
+    {  50, 205,  50, "LimeGreen"              },
+    { 250, 240, 230, "linen"                  },
+    { 255,  0,  255, "magenta"                },
+    { 255,  0,  255, "magenta1"               },
+    { 238,  0,  238, "magenta2"               },
+    { 205,  0,  205, "magenta3"               },
+    { 139,  0,  139, "magenta4"               },
+    { 176,  48,  96, "maroon"                 },
+    { 255,  52, 179, "maroon1"                },
+    { 238,  48, 167, "maroon2"                },
+    { 205,  41, 144, "maroon3"                },
+    { 139,  28,  98, "maroon4"                },
+    { 102, 205, 170, "medium aquamarine"      },
+    {   0,   0, 205, "medium blue"            },
+    { 186,  85, 211, "medium orchid"          },
+    { 147, 112, 219, "medium purple"          },
+    {  60, 179, 113, "medium sea green"       },
+    { 123, 104, 238, "medium slate blue"      },
+    {   0, 250, 154, "medium spring green"    },
+    {  72, 209, 204, "medium turquoise"       },
+    { 199,  21, 133, "medium violet red"      },
+    { 102, 205, 170, "MediumAquamarine"       },
+    {   0,   0, 205, "MediumBlue"             },
+    { 186,  85, 211, "MediumOrchid"           },
+    { 224, 102, 255, "MediumOrchid1"          },
+    { 209,  95, 238, "MediumOrchid2"          },
+    { 180,  82, 205, "MediumOrchid3"          },
+    { 122,  55, 139, "MediumOrchid4"          },
+    { 147, 112, 219, "MediumPurple"           },
+    { 171, 130, 255, "MediumPurple1"          },
+    { 159, 121, 238, "MediumPurple2"          },
+    { 137, 104, 205, "MediumPurple3"          },
+    {  93,  71, 139, "MediumPurple4"          },
+    {  60, 179, 113, "MediumSeaGreen"         },
+    { 123, 104, 238, "MediumSlateBlue"        },
+    {   0, 250, 154, "MediumSpringGreen"      },
+    {  72, 209, 204, "MediumTurquoise"        },
+    { 199,  21, 133, "MediumVioletRed"        },
+    {  25,  25, 112, "midnight blue"          },
+    {  25,  25, 112, "MidnightBlue"           },
+    { 245, 255, 250, "mint cream"             },
+    { 245, 255, 250, "MintCream"              },
+    { 255, 228, 225, "misty rose"             },
+    { 255, 228, 225, "MistyRose"              },
+    { 255, 228, 225, "MistyRose1"             },
+    { 238, 213, 210, "MistyRose2"             },
+    { 205, 183, 181, "MistyRose3"             },
+    { 139, 125, 123, "MistyRose4"             },
+    { 255, 228, 181, "moccasin"               },
+    { 255, 222, 173, "navajo white"           },
+    { 255, 222, 173, "NavajoWhite"            },
+    { 255, 222, 173, "NavajoWhite1"           },
+    { 238, 207, 161, "NavajoWhite2"           },
+    { 205, 179, 139, "NavajoWhite3"           },
+    { 139, 121,  94, "NavajoWhite4"           },
+    {   0,   0, 128, "navy"                   },
+    {   0,   0, 128, "navy blue"              },
+    {   0,   0, 128, "NavyBlue"               },
+    { 253, 245, 230, "old lace"               },
+    { 253, 245, 230, "OldLace"                },
+    { 128, 128,   0, "olive"                  },
+    { 107, 142,  35, "olive drab"             },
+    { 107, 142,  35, "OliveDrab"              },
+    { 192, 255,  62, "OliveDrab1"             },
+    { 179, 238,  58, "OliveDrab2"             },
+    { 154, 205,  50, "OliveDrab3"             },
+    { 105, 139,  34, "OliveDrab4"             },
+    { 255, 165,   0, "orange"                 },
+    { 255,  69,   0, "orange red"             },
+    { 255, 165,   0, "orange1"                },
+    { 238, 154,   0, "orange2"                },
+    { 205, 133,   0, "orange3"                },
+    { 139,  90,   0, "orange4"                },
+    { 255,  69,   0, "OrangeRed"              },
+    { 255,  69,   0, "OrangeRed1"             },
+    { 238,  64,   0, "OrangeRed2"             },
+    { 205,  55,   0, "OrangeRed3"             },
+    { 139,  37,   0, "OrangeRed4"             },
+    { 218, 112, 214, "orchid"                 },
+    { 255, 131, 250, "orchid1"                },
+    { 238, 122, 233, "orchid2"                },
+    { 205, 105, 201, "orchid3"                },
+    { 139,  71, 137, "orchid4"                },
+    { 238, 232, 170, "pale goldenrod"         },
+    { 152, 251, 152, "pale green"             },
+    { 175, 238, 238, "pale turquoise"         },
+    { 219, 112, 147, "pale violet red"        },
+    { 238, 232, 170, "PaleGoldenrod"          },
+    { 152, 251, 152, "PaleGreen"              },
+    { 154, 255, 154, "PaleGreen1"             },
+    { 144, 238, 144, "PaleGreen2"             },
+    { 124, 205, 124, "PaleGreen3"             },
+    {  84, 139,  84, "PaleGreen4"             },
+    { 175, 238, 238, "PaleTurquoise"          },
+    { 187, 255, 255, "PaleTurquoise1"         },
+    { 174, 238, 238, "PaleTurquoise2"         },
+    { 150, 205, 205, "PaleTurquoise3"         },
+    { 102, 139, 139, "PaleTurquoise4"         },
+    { 219, 112, 147, "PaleVioletRed"          },
+    { 255, 130, 171, "PaleVioletRed1"         },
+    { 238, 121, 159, "PaleVioletRed2"         },
+    { 205, 104, 137, "PaleVioletRed3"         },
+    { 139,  71,  93, "PaleVioletRed4"         },
+    { 255, 239, 213, "papaya whip"            },
+    { 255, 239, 213, "PapayaWhip"             },
+    { 255, 218, 185, "peach puff"             },
+    { 255, 218, 185, "PeachPuff"              },
+    { 255, 218, 185, "PeachPuff1"             },
+    { 238, 203, 173, "PeachPuff2"             },
+    { 205, 175, 149, "PeachPuff3"             },
+    { 139, 119, 101, "PeachPuff4"             },
+    { 205, 133,  63, "peru"                   },
+    { 255, 192, 203, "pink"                   },
+    { 255, 181, 197, "pink1"                  },
+    { 238, 169, 184, "pink2"                  },
+    { 205, 145, 158, "pink3"                  },
+    { 139,  99, 108, "pink4"                  },
+    { 221, 160, 221, "plum"                   },
+    { 255, 187, 255, "plum1"                  },
+    { 238, 174, 238, "plum2"                  },
+    { 205, 150, 205, "plum3"                  },
+    { 139, 102, 139, "plum4"                  },
+    { 176, 224, 230, "powder blue"            },
+    { 176, 224, 230, "PowderBlue"             },
+    { 160,  32, 240, "purple"                 },
+    { 155,  48, 255, "purple1"                },
+    { 145,  44, 238, "purple2"                },
+    { 125,  38, 205, "purple3"                },
+    {  85,  26, 139, "purple4"                },
+    { 102,  51, 153, "rebecca purple"         },
+    { 102,  51, 153, "RebeccaPurple"          },
+    { 255,   0,   0, "red"                    },
+    { 255,   0,   0, "red1"                   },
+    { 238,   0,   0, "red2"                   },
+    { 205,   0,   0, "red3"                   },
+    { 139,   0,   0, "red4"                   },
+    { 188, 143, 143, "rosy brown"             },
+    { 188, 143, 143, "RosyBrown"              },
+    { 255, 193, 193, "RosyBrown1"             },
+    { 238, 180, 180, "RosyBrown2"             },
+    { 205, 155, 155, "RosyBrown3"             },
+    { 139, 105, 105, "RosyBrown4"             },
+    {  65, 105, 225, "royal blue"             },
+    {  65, 105, 225, "RoyalBlue"              },
+    {  72, 118, 255, "RoyalBlue1"             },
+    {  67, 110, 238, "RoyalBlue2"             },
+    {  58,  95, 205, "RoyalBlue3"             },
+    {  39,  64, 139, "RoyalBlue4"             },
+    { 139,  69,  19, "saddle brown"           },
+    { 139,  69,  19, "SaddleBrown"            },
+    { 250, 128, 114, "salmon"                 },
+    { 255, 140, 105, "salmon1"                },
+    { 238, 130,  98, "salmon2"                },
+    { 205, 112,  84, "salmon3"                },
+    { 139,  76,  57, "salmon4"                },
+    { 244, 164,  96, "sandy brown"            },
+    { 244, 164,  96, "SandyBrown"             },
+    {  46, 139,  87, "sea green"              },
+    {  46, 139,  87, "SeaGreen"               },
+    {  84, 255, 159, "SeaGreen1"              },
+    {  78, 238, 148, "SeaGreen2"              },
+    {  67, 205, 128, "SeaGreen3"              },
+    {  46, 139,  87, "SeaGreen4"              },
+    { 255, 245, 238, "seashell"               },
+    { 255, 245, 238, "seashell1"              },
+    { 238, 229, 222, "seashell2"              },
+    { 205, 197, 191, "seashell3"              },
+    { 139, 134, 130, "seashell4"              },
+    { 160,  82,  45, "sienna"                 },
+    { 255, 130,  71, "sienna1"                },
+    { 238, 121,  66, "sienna2"                },
+    { 205, 104,  57, "sienna3"                },
+    { 139,  71,  38, "sienna4"                },
+    { 192, 192, 192, "silver"                 },
+    { 135, 206, 235, "sky blue"               },
+    { 135, 206, 235, "SkyBlue"                },
+    { 135, 206, 255, "SkyBlue1"               },
+    { 126, 192, 238, "SkyBlue2"               },
+    { 108, 166, 205, "SkyBlue3"               },
+    {  74, 112, 139, "SkyBlue4"               },
+    { 106,  90, 205, "slate blue"             },
+    { 112, 128, 144, "slate gray"             },
+    { 112, 128, 144, "slate grey"             },
+    { 106,  90, 205, "SlateBlue"              },
+    { 131, 111, 255, "SlateBlue1"             },
+    { 122, 103, 238, "SlateBlue2"             },
+    { 105,  89, 205, "SlateBlue3"             },
+    {  71,  60, 139, "SlateBlue4"             },
+    { 112, 128, 144, "SlateGray"              },
+    { 198, 226, 255, "SlateGray1"             },
+    { 185, 211, 238, "SlateGray2"             },
+    { 159, 182, 205, "SlateGray3"             },
+    { 108, 123, 139, "SlateGray4"             },
+    { 112, 128, 144, "SlateGrey"              },
+    { 255, 250, 250, "snow"                   },
+    { 255, 250, 250, "snow1"                  },
+    { 238, 233, 233, "snow2"                  },
+    { 205, 201, 201, "snow3"                  },
+    { 139, 137, 137, "snow4"                  },
+    {   0, 255, 127, "spring green"           },
+    {   0, 255, 127, "SpringGreen"            },
+    {   0, 255, 127, "SpringGreen1"           },
+    {   0, 238, 118, "SpringGreen2"           },
+    {   0, 205, 102, "SpringGreen3"           },
+    {   0, 139,  69, "SpringGreen4"           },
+    {  70, 130, 180, "steel blue"             },
+    {  70, 130, 180, "SteelBlue"              },
+    {  99, 184, 255, "SteelBlue1"             },
+    {  92, 172, 238, "SteelBlue2"             },
+    {  79, 148, 205, "SteelBlue3"             },
+    {  54, 100, 139, "SteelBlue4"             },
+    { 210, 180, 140, "tan"                    },
+    { 255, 165,  79, "tan1"                   },
+    { 238, 154,  73, "tan2"                   },
+    { 205, 133,  63, "tan3"                   },
+    { 139,  90,  43, "tan4"                   },
+    {   0, 128, 128, "teal"                   },
+    { 216, 191, 216, "thistle"                },
+    { 255, 225, 255, "thistle1"               },
+    { 238, 210, 238, "thistle2"               },
+    { 205, 181, 205, "thistle3"               },
+    { 139, 123, 139, "thistle4"               },
+    { 255,  99,  71, "tomato"                 },
+    { 255,  99,  71, "tomato1"                },
+    { 238,  92,  66, "tomato2"                },
+    { 205,  79,  57, "tomato3"                },
+    { 139,  54,  38, "tomato4"                },
+    {  64, 224, 208, "turquoise"              },
+    {   0, 245, 255, "turquoise1"             },
+    {   0, 229, 238, "turquoise2"             },
+    {   0, 197, 205, "turquoise3"             },
+    {   0, 134, 139, "turquoise4"             },
+    { 238, 130, 238, "violet"                 },
+    { 208,  32, 144, "violet red"             },
+    { 208,  32, 144, "VioletRed"              },
+    { 255,  62, 150, "VioletRed1"             },
+    { 238,  58, 140, "VioletRed2"             },
+    { 205,  50, 120, "VioletRed3"             },
+    { 139,  34,  82, "VioletRed4"             },
+    { 128, 128, 128, "web gray"               },
+    {   0, 128,   0, "web green"              },
+    { 128, 128, 128, "web grey"               },
+    { 128,   0,   0, "web maroon"             },
+    { 128,   0, 128, "web purple"             },
+    { 128, 128, 128, "WebGray"                },
+    {  0,  128,   0, "WebGreen"               },
+    { 128, 128, 128, "WebGrey"                },
+    { 128,   0,   0, "WebMaroon"              },
+    { 128,   0, 128, "WebPurple"              },
+    { 245, 222, 179, "wheat"                  },
+    { 255, 231, 186, "wheat1"                 },
+    { 238, 216, 174, "wheat2"                 },
+    { 205, 186, 150, "wheat3"                 },
+    { 139, 126, 102, "wheat4"                 },
+    { 255, 255, 255, "white"                  },
+    { 245, 245, 245, "white smoke"            },
+    { 245, 245, 245, "WhiteSmoke"             },
+    { 190, 190, 190, "x11 gray"               },
+    {   0, 255,   0, "x11 green"              },
+    { 190, 190, 190, "x11 grey"               },
+    { 176,  48,  96, "x11 maroon"             },
+    { 160,  32, 240, "x11 purple"             },
+    { 190, 190, 190, "X11Gray"                },
+    {   0, 255,   0, "X11Green"               },
+    { 190, 190, 190, "X11Grey"                },
+    { 176,  48,  96, "X11Maroon"              },
+    { 160,  32, 240, "X11Purple"              },
+    { 255, 255,   0, "yellow"                 },
+    { 154, 205,  50, "yellow green"           },
+    { 255, 255,   0, "yellow1"                },
+    { 238, 238,   0, "yellow2"                },
+    { 205, 205,   0, "yellow3"                },
+    { 139, 139,   0, "yellow4"                },
+    { 154, 205,  50, "YellowGreen"            },
+};
+
+Bool
+dixLookupBuiltinColor(int screen,
+                      char *name,
+                      unsigned int len,
+                      unsigned short *pred,
+                      unsigned short *pgreen,
+                      unsigned short *pblue)
+{
+    int low = 0;
+    int high = ARRAY_SIZE(BuiltinColors) - 1;
+
+    while (high >= low) {
+        int mid = (low + high) / 2;
+        const BuiltinColor *c = &BuiltinColors[mid];
+        const int currentLen = strlen(c->name);
+        const int r = strncasecmp(c->name, name, min(len, currentLen));
+
+        if (r == 0) {
+            if (len == currentLen) {
+                *pred = c->red * 0x101;
+                *pgreen = c->green * 0x101;
+                *pblue = c->blue * 0x101;
+                return TRUE;
+            } else if (len > currentLen) {
+                low = mid + 1;
+            } else {
+                high = mid - 1;
+            }
+        } else if (r > 0) {
+            high = mid - 1;
+        } else {
+            low = mid + 1;
+        }
+    }
+    return FALSE;
+}
diff --git a/src/xpm/dix-config.h b/src/xpm/dix-config.h
new file mode 100644
index 0000000..5137e8a
--- /dev/null
+++ b/src/xpm/dix-config.h
@@ -0,0 +1 @@
+// Empty file making color.c able to compile without modifications.
diff --git a/src/xpm/dix/dix_priv.h b/src/xpm/dix/dix_priv.h
new file mode 100644
index 0000000..005da83
--- /dev/null
+++ b/src/xpm/dix/dix_priv.h
@@ -0,0 +1,14 @@
+#ifndef DIX_PRIV_H
+#define DIX_PRIV_H
+
+#define TRUE 1
+#define FALSE 0
+
+#define ARRAY_SIZE(a)  (sizeof((a)) / sizeof((a)[0]))
+
+#include <string.h>
+#include <strings.h>
+
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+#endif // DIX_PRIV_H
diff --git a/src/xpm/include/dix.h b/src/xpm/include/dix.h
new file mode 100644
index 0000000..2a7125a
--- /dev/null
+++ b/src/xpm/include/dix.h
@@ -0,0 +1,14 @@
+#ifndef DIX_H
+#define DIX_H
+
+#include <X11/Xlib.h>
+
+Bool
+dixLookupBuiltinColor(int screen,
+                      char *name,
+                      unsigned int len,
+                      unsigned short *pred,
+                      unsigned short *pgreen,
+                      unsigned short *pblue);
+
+#endif // DIX_H
diff --git a/subprojects/.gitignore b/subprojects/.gitignore
new file mode 100644
index 0000000..7ba62ce
--- /dev/null
+++ b/subprojects/.gitignore
@@ -0,0 +1,3 @@
+packagecache/
+googletest-1.17.0/
+.wraplock
\ No newline at end of file
diff --git a/subprojects/gtest.wrap b/subprojects/gtest.wrap
new file mode 100644
index 0000000..9902a4f
--- /dev/null
+++ b/subprojects/gtest.wrap
@@ -0,0 +1,16 @@
+[wrap-file]
+directory = googletest-1.17.0
+source_url = https://github.com/google/googletest/archive/refs/tags/v1.17.0.tar.gz
+source_filename = googletest-1.17.0.tar.gz
+source_hash = 65fab701d9829d38cb77c14acdc431d2108bfdbf8979e40eb8ae567edf10b27c
+patch_filename = gtest_1.17.0-4_patch.zip
+patch_url = https://wrapdb.mesonbuild.com/v2/gtest_1.17.0-4/get_patch
+patch_hash = 3abf7662d09db706453a5b064a1e914678c74b9d9b0b19382747ca561d0d8750
+source_fallback_url = https://github.com/mesonbuild/wrapdb/releases/download/gtest_1.17.0-4/googletest-1.17.0.tar.gz
+wrapdb_version = 1.17.0-4
+
+[provide]
+gtest = gtest_dep
+gtest_main = gtest_main_dep
+gmock = gmock_dep
+gmock_main = gmock_main_dep
diff --git a/test/args.cc b/test/args.cc
new file mode 100644
index 0000000..22159d2
--- /dev/null
+++ b/test/args.cc
@@ -0,0 +1,412 @@
+#include "args.hh"
+
+#include <cstddef>
+#include <gtest/gtest.h>
+#include <memory>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+#define SETUP_OPTIONS(args)                                                    \
+  auto short_only = (args)->option('a', "", "an option");                      \
+  auto short_long = (args)->option('b', "bold", "set font style to bold");     \
+  auto long_only = (args)->option("cold", "use if it is cold outside");        \
+  auto short_only_req = (args)->option_argument('d', "", "", "distance");      \
+  auto short_long_req = (args)->option_argument(                               \
+      'e', "eat", "FOOD", "what to order, what to eat?");                      \
+  auto long_only_req =                                                         \
+      (args)->option_argument("form", "", "circle, shape or something else?"); \
+  auto short_only_opt = (args)->option_argument('g', "", "", "", false);       \
+  auto short_long_opt = (args)->option_argument('h', "hold", "", "", false);   \
+  auto long_only_opt = (args)->option_argument("invert", "", "", false);
+
+namespace {
+
+class Arguments {
+ public:
+  [[nodiscard]] int c() const { return static_cast<int>(str_.size()); };
+  [[nodiscard]] char** v() const { return ptr_.get(); }
+
+  explicit Arguments(std::vector<std::string> str) : str_(std::move(str)) {
+    ptr_ = std::make_unique<char*[]>(str_.size());
+    for (size_t i = 0; i < str_.size(); ++i) {
+      ptr_[i] = const_cast<char*>(str_[i].c_str());
+    }
+  }
+
+  Arguments(Arguments const&) = delete;
+  Arguments& operator=(Arguments const&) = delete;
+
+ private:
+  std::unique_ptr<char*[]> ptr_;
+  std::vector<std::string> str_;
+};
+
+class Builder {
+ public:
+  Arguments build() { return Arguments(std::move(str_)); }
+
+  Builder& add(std::string str) {
+    str_.emplace_back(std::move(str));
+    return *this;
+  }
+
+ private:
+  std::vector<std::string> str_;
+};
+
+}  // namespace
+
+TEST(args, empty) {
+  auto args = Args::create();
+  EXPECT_TRUE(args->run(0, nullptr));
+  {
+    std::stringstream ss;
+    args->print_error(ss);
+    EXPECT_EQ("", ss.str());
+  }
+  {
+    std::stringstream ss;
+    args->print_help(ss);
+    EXPECT_EQ("", ss.str());
+  }
+}
+
+TEST(args, options_not_set) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  EXPECT_TRUE(args->run(0, nullptr));
+  EXPECT_FALSE(short_only->is_set());
+  EXPECT_FALSE(short_long->is_set());
+  EXPECT_FALSE(long_only->is_set());
+  EXPECT_FALSE(short_only_req->is_set());
+  EXPECT_FALSE(short_long_req->is_set());
+  EXPECT_FALSE(long_only_req->is_set());
+  EXPECT_FALSE(short_only_opt->is_set());
+  EXPECT_FALSE(short_long_opt->is_set());
+  EXPECT_FALSE(long_only_opt->is_set());
+}
+
+TEST(args, options_not_set_arguments) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo").add("bar").add("fum").build();
+  std::vector<std::string_view> out;
+  EXPECT_TRUE(args->run(arg.c(), arg.v(), &out));
+  ASSERT_EQ(2, out.size());
+  EXPECT_EQ("bar", out[0]);
+  EXPECT_EQ("fum", out[1]);
+}
+
+TEST(args, options_set) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo")
+                 .add("-a")
+                 .add("-b")
+                 .add("--cold")
+                 .add("-d")
+                 .add("10")
+                 .add("-e")
+                 .add("hamburger")
+                 .add("--form=circle")
+                 .add("-g")
+                 .add("-h")
+                 .add("--invert")
+                 .build();
+  std::vector<std::string_view> out;
+  EXPECT_TRUE(args->run(arg.c(), arg.v(), &out));
+  EXPECT_TRUE(out.empty());
+  EXPECT_TRUE(short_only->is_set());
+  EXPECT_TRUE(short_long->is_set());
+  EXPECT_TRUE(long_only->is_set());
+  EXPECT_TRUE(short_only_req->is_set());
+  EXPECT_TRUE(short_only_req->has_argument());
+  EXPECT_EQ("10", short_only_req->argument());
+  EXPECT_TRUE(short_long_req->is_set());
+  EXPECT_TRUE(short_long_req->has_argument());
+  EXPECT_EQ("hamburger", short_long_req->argument());
+  EXPECT_TRUE(long_only_req->is_set());
+  EXPECT_TRUE(long_only_req->has_argument());
+  EXPECT_EQ("circle", long_only_req->argument());
+  EXPECT_TRUE(short_only_opt->is_set());
+  EXPECT_FALSE(short_only_opt->has_argument());
+  EXPECT_TRUE(short_long_opt->is_set());
+  EXPECT_FALSE(short_long_opt->has_argument());
+  EXPECT_TRUE(long_only_opt->is_set());
+  EXPECT_FALSE(long_only_opt->has_argument());
+}
+
+TEST(args, options_set_variant) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo")
+                 .add("-a")
+                 .add("--bold")
+                 .add("--cold")
+                 .add("-d")
+                 .add("10")
+                 .add("--eat=hamburger")
+                 .add("--form")
+                 .add("circle")
+                 .add("-g")
+                 .add("--hold=foo")
+                 .add("--invert=bar")
+                 .build();
+  std::vector<std::string_view> out;
+  EXPECT_TRUE(args->run(arg.c(), arg.v(), &out));
+  EXPECT_TRUE(out.empty());
+  EXPECT_TRUE(short_only->is_set());
+  EXPECT_TRUE(short_long->is_set());
+  EXPECT_TRUE(long_only->is_set());
+  EXPECT_TRUE(short_only_req->is_set());
+  EXPECT_TRUE(short_only_req->has_argument());
+  EXPECT_EQ("10", short_only_req->argument());
+  EXPECT_TRUE(short_long_req->is_set());
+  EXPECT_TRUE(short_long_req->has_argument());
+  EXPECT_EQ("hamburger", short_long_req->argument());
+  EXPECT_TRUE(long_only_req->is_set());
+  EXPECT_TRUE(long_only_req->has_argument());
+  EXPECT_EQ("circle", long_only_req->argument());
+  EXPECT_TRUE(short_only_opt->is_set());
+  EXPECT_FALSE(short_only_opt->has_argument());
+  EXPECT_TRUE(short_long_opt->is_set());
+  EXPECT_TRUE(short_long_opt->has_argument());
+  EXPECT_EQ("foo", short_long_opt->argument());
+  EXPECT_TRUE(long_only_opt->is_set());
+  EXPECT_TRUE(long_only_opt->has_argument());
+  EXPECT_EQ("bar", long_only_opt->argument());
+}
+
+TEST(args, options_short_missing_value) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo").add("-d").build();
+  EXPECT_FALSE(args->run(arg.c(), arg.v()));
+  std::stringstream ss;
+  args->print_error(ss);
+  EXPECT_EQ("foo: option requires an argument -- 'd'\n", ss.str());
+}
+
+TEST(args, options_short_unknown_value) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo").add("-X").build();
+  EXPECT_FALSE(args->run(arg.c(), arg.v()));
+  std::stringstream ss;
+  args->print_error(ss);
+  EXPECT_EQ("foo: invalid option -- 'X'\n", ss.str());
+}
+
+TEST(args, options_long_missing_value) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo").add("--form").build();
+  EXPECT_FALSE(args->run(arg.c(), arg.v()));
+  std::stringstream ss;
+  args->print_error(ss);
+  EXPECT_EQ("foo: option '--form' requires an argument\n", ss.str());
+}
+
+TEST(args, options_long_unsupported_value) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo").add("--cold=feet").build();
+  EXPECT_FALSE(args->run(arg.c(), arg.v()));
+  std::stringstream ss;
+  args->print_error(ss);
+  EXPECT_EQ("foo: option '--cold' doesn't allow an argument\n", ss.str());
+}
+
+TEST(args, options_long_unknown_value) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo").add("--experience").build();
+  EXPECT_FALSE(args->run(arg.c(), arg.v()));
+  std::stringstream ss;
+  args->print_error(ss);
+  EXPECT_EQ("foo: unrecognized option '--experience'\n", ss.str());
+}
+
+TEST(args, options_short_dash_value) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo").add("-d").add("-").build();
+  std::vector<std::string_view> out;
+  EXPECT_TRUE(args->run(arg.c(), arg.v(), &out));
+  EXPECT_TRUE(out.empty());
+  EXPECT_TRUE(short_only_req->is_set());
+  EXPECT_TRUE(short_only_req->has_argument());
+  EXPECT_EQ("-", short_only_req->argument());
+}
+
+TEST(args, options_long_dash_dash_value) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo").add("--eat").add("--").build();
+  std::vector<std::string_view> out;
+  EXPECT_TRUE(args->run(arg.c(), arg.v(), &out));
+  EXPECT_TRUE(out.empty());
+  EXPECT_TRUE(short_long_req->is_set());
+  EXPECT_TRUE(short_long_req->has_argument());
+  EXPECT_EQ("--", short_long_req->argument());
+}
+
+TEST(args, options_dash_dash) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo")
+                 .add("--")
+                 .add("-d")
+                 .add("10")
+                 .add("--eat=hamburger")
+                 .add("--form")
+                 .add("circle")
+                 .build();
+  std::vector<std::string_view> out;
+  EXPECT_TRUE(args->run(arg.c(), arg.v(), &out));
+  ASSERT_EQ(5, out.size());
+  EXPECT_EQ("-d", out[0]);
+  EXPECT_EQ("10", out[1]);
+  EXPECT_EQ("--eat=hamburger", out[2]);
+  EXPECT_EQ("--form", out[3]);
+  EXPECT_EQ("circle", out[4]);
+  EXPECT_FALSE(short_only_req->is_set());
+  EXPECT_FALSE(short_long_req->is_set());
+  EXPECT_FALSE(long_only_req->is_set());
+}
+
+TEST(args, options_dash_dash_end) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  Builder builder;
+  auto arg = builder.add("foo").add("--").build();
+  std::vector<std::string_view> out;
+  EXPECT_TRUE(args->run(arg.c(), arg.v(), &out));
+  EXPECT_TRUE(out.empty());
+}
+
+TEST(args, help) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  std::stringstream ss;
+  args->print_help(ss, 50);
+  EXPECT_EQ(R"(Mandatory arguments to long options are mandatory
+ for short options too.
+  -a                  an option
+  -b, --bold          set font style to bold
+      --cold          use if it is cold outside
+  -d ARG              distance
+  -e, --eat=FOOD      what to order, what to eat?
+      --form=ARG      circle, shape or something
+                       else?
+  -g
+  -h, --hold=[ARG]
+      --invert=[ARG]
+)",
+            ss.str());
+}
+
+TEST(args, help_wide) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  std::stringstream ss;
+  args->print_help(ss, 100);
+  EXPECT_EQ(
+      R"(Mandatory arguments to long options are mandatory for short options too.
+  -a                  an option
+  -b, --bold          set font style to bold
+      --cold          use if it is cold outside
+  -d ARG              distance
+  -e, --eat=FOOD      what to order, what to eat?
+      --form=ARG      circle, shape or something else?
+  -g
+  -h, --hold=[ARG]
+      --invert=[ARG]
+)",
+      ss.str());
+}
+
+TEST(args, help_narrow) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  std::stringstream ss;
+  args->print_help(ss, 35);
+  EXPECT_EQ(R"(Mandatory arguments to long options
+ are mandatory for short options
+ too.
+  -a          an option
+  -b, --bold  set font style to
+               bold
+      --cold  use if it is cold
+               outside
+  -d ARG      distance
+  -e, --eat=FOOD
+what to order, what to eat?
+      --form=ARG
+circle, shape or something else?
+  -g
+  -h, --hold=[ARG]
+      --invert=[ARG]
+)",
+            ss.str());
+}
+
+TEST(args, help_very_narrow) {
+  auto args = Args::create();
+  SETUP_OPTIONS(args);
+  std::stringstream ss;
+  args->print_help(ss, 20);
+  EXPECT_EQ(R"(Mandatory arguments
+ to long options are
+ mandatory for short
+ options too.
+  -a      an option
+  -b, --bold
+set font style to
+ bold
+      --cold
+use if it is cold
+ outside
+  -d ARG  distance
+  -e, --eat=FOOD
+what to order, what
+ to eat?
+      --form=ARG
+circle, shape or
+ something else?
+  -g
+  -h, --hold=[ARG]
+      --invert=[ARG]
+)",
+            ss.str());
+}
+
+TEST(args, help_long_word) {
+  auto args = Args::create();
+  std::stringstream ss;
+  auto opt = args->option('a', "arg", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
+  args->print_help(ss, 20);
+  EXPECT_EQ(R"(Mandatory arguments
+ to long options are
+ mandatory for short
+ options too.
+  -a, --arg
+aaaaaaaaaaaaaaaaaaa-
+aaaaaaaaaaaaaaaaaaa
+)",
+            ss.str());
+}
diff --git a/test/cfg.cc b/test/cfg.cc
new file mode 100644
index 0000000..0c27989
--- /dev/null
+++ b/test/cfg.cc
@@ -0,0 +1,190 @@
+#include "cfg.hh"
+
+#include "testdir.hh"
+#include "testenv.hh"
+
+#include <fstream>
+#include <gtest/gtest.h>
+#include <string>
+#include <vector>
+
+namespace {
+
+class ConfigTest : public TestEnv {
+ protected:
+  void SetUp() override { ASSERT_TRUE(dir_.good()); }
+
+  TestDir dir_;
+};
+
+}  // namespace
+
+TEST_F(ConfigTest, empty) {
+  auto does_not_exist = dir_.path() / "does-not-exist";
+  std::vector<std::string> errors;
+  auto cfg = cfg::load_one(does_not_exist, errors);
+  ASSERT_TRUE(cfg);
+  EXPECT_EQ(1, errors.size());
+
+  EXPECT_FALSE(cfg->has(""));
+  EXPECT_FALSE(cfg->get("").has_value());
+
+  EXPECT_FALSE(cfg->has("foo"));
+  EXPECT_FALSE(cfg->get("foo").has_value());
+}
+
+TEST_F(ConfigTest, values) {
+  auto file = dir_.path() / "file";
+  {
+    std::ofstream out(file);
+    out << "# Comment\n"
+        << "key=value\n"
+        << " foo = bar \n"
+        << "i1 = 12\n"
+        << "b1 = true\n"
+        << "b2=FaLSe\n"
+        << "i2 = -12313\n";
+  }
+  std::vector<std::string> errors;
+  auto cfg = cfg::load_one(file, errors);
+  ASSERT_TRUE(cfg);
+  EXPECT_EQ(0, errors.size());
+
+  EXPECT_FALSE(cfg->has(""));
+  EXPECT_FALSE(cfg->get("").has_value());
+
+  EXPECT_TRUE(cfg->has("key"));
+  EXPECT_EQ("value", cfg->get("key").value_or(""));
+
+  EXPECT_TRUE(cfg->has("foo"));
+  EXPECT_EQ("bar", cfg->get("foo").value_or(""));
+  EXPECT_FALSE(cfg->get_int64("foo").has_value());
+
+  EXPECT_TRUE(cfg->has("i1"));
+  EXPECT_EQ("12", cfg->get("i1").value_or(""));
+  EXPECT_EQ(12, cfg->get_int64("i1").value_or(0));
+  EXPECT_EQ(12, cfg->get_uint64("i1").value_or(0));
+
+  EXPECT_TRUE(cfg->has("b1"));
+  EXPECT_EQ("true", cfg->get("b1").value_or(""));
+  EXPECT_TRUE(cfg->get_bool("b1").value_or(false));
+
+  EXPECT_TRUE(cfg->has("b2"));
+  EXPECT_EQ("FaLSe", cfg->get("b2").value_or(""));
+  EXPECT_FALSE(cfg->get_bool("b2").value_or(true));
+
+  EXPECT_TRUE(cfg->has("i2"));
+  EXPECT_EQ("-12313", cfg->get("i2").value_or(""));
+  EXPECT_EQ(-12313, cfg->get_int64("i2").value_or(0));
+  EXPECT_EQ(0, cfg->get_uint64("i2").value_or(0));
+}
+
+TEST_F(ConfigTest, bools) {
+  auto file = dir_.path() / "file";
+  {
+    std::ofstream out(file);
+    out << "key1=True\n"
+        << "key2=yES\n"
+        << "key3=false\n"
+        << "key4=NO\n"
+        << "key5=ja\n";
+  }
+  std::vector<std::string> errors;
+  auto cfg = cfg::load_one(file, errors);
+  ASSERT_TRUE(cfg);
+  EXPECT_EQ(0, errors.size());
+
+  EXPECT_TRUE(cfg->get_bool("key1").value_or(false));
+  EXPECT_TRUE(cfg->get_bool("key2").value_or(false));
+  EXPECT_FALSE(cfg->get_bool("key3").value_or(true));
+  EXPECT_FALSE(cfg->get_bool("key4").value_or(true));
+  EXPECT_FALSE(cfg->get_bool("key5").has_value());
+}
+
+TEST_F(ConfigTest, errors) {
+  auto file = dir_.path() / "file";
+  {
+    std::ofstream out(file);
+    out << "bad line\n"
+        << "key=value\n"
+        << "key=duplicate\n";
+  }
+  std::vector<std::string> errors;
+  auto cfg = cfg::load_one(file, errors);
+  ASSERT_TRUE(cfg);
+  EXPECT_EQ(2, errors.size());
+}
+
+TEST_F(ConfigTest, merge) {
+  auto dir1 = dir_.path() / "dir1";
+  auto dir2 = dir_.path() / "dir2";
+  auto dir3 = dir_.path() / "dir3";
+  std::filesystem::create_directory(dir1);
+  std::filesystem::create_directory(dir2);
+  std::filesystem::create_directory(dir3);
+  setenv("XDG_CONFIG_HOME", dir1);
+  setenv("XDG_CONFIG_DIRS", dir2.string() + ":" + dir3.string());
+  auto file1 = dir1 / "file";
+  auto file2 = dir2 / "file";
+  {
+    std::ofstream out(file2);
+    out << "key1 = value1\n"
+        << "key2 = value2\n";
+  }
+  {
+    std::ofstream out(file1);
+    out << "key1 = 12\n"
+        << "key3 = value3";
+  }
+  std::vector<std::string> errors;
+  auto cfg = cfg::load_all("file", errors);
+  ASSERT_TRUE(cfg);
+  EXPECT_EQ(0, errors.size());
+
+  EXPECT_FALSE(cfg->has(""));
+  EXPECT_FALSE(cfg->get("").has_value());
+
+  EXPECT_TRUE(cfg->has("key1"));
+  EXPECT_EQ("12", cfg->get("key1").value_or(""));
+
+  EXPECT_TRUE(cfg->has("key2"));
+  EXPECT_EQ("value2", cfg->get("key2").value_or(""));
+
+  EXPECT_TRUE(cfg->has("key3"));
+  EXPECT_EQ("value3", cfg->get("key3").value_or(""));
+}
+
+TEST_F(ConfigTest, merge_errors) {
+  auto dir1 = dir_.path() / "dir1";
+  auto dir2 = dir_.path() / "dir2";
+  std::filesystem::create_directory(dir1);
+  std::filesystem::create_directory(dir2);
+  setenv("XDG_CONFIG_HOME", dir1);
+  setenv("XDG_CONFIG_DIRS", dir2);
+  auto file1 = dir1 / "file";
+  auto file2 = dir2 / "file";
+  {
+    std::ofstream out(file2);
+    out << "key1 = value1\n"
+        << "key2 = value2\n";
+  }
+  {
+    std::ofstream out(file1);
+    out << "invalid line";
+  }
+  std::vector<std::string> errors;
+  auto cfg = cfg::load_all("file", errors);
+  ASSERT_TRUE(cfg);
+  EXPECT_EQ(1, errors.size());
+
+  EXPECT_FALSE(cfg->has(""));
+  EXPECT_FALSE(cfg->get("").has_value());
+
+  EXPECT_TRUE(cfg->has("key1"));
+  EXPECT_EQ("value1", cfg->get("key1").value_or(""));
+
+  EXPECT_TRUE(cfg->has("key2"));
+  EXPECT_EQ("value2", cfg->get("key2").value_or(""));
+
+  EXPECT_FALSE(cfg->has("key3"));
+}
diff --git a/test/data/test.jpeg b/test/data/test.jpeg
new file mode 100644
index 0000000..0bc367a
Binary files /dev/null and b/test/data/test.jpeg differ
diff --git a/test/data/test.png b/test/data/test.png
new file mode 100644
index 0000000..6c4877b
Binary files /dev/null and b/test/data/test.png differ
diff --git a/test/data/test.svg b/test/data/test.svg
new file mode 100644
index 0000000..155a68a
--- /dev/null
+++ b/test/data/test.svg
@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   width="10"
+   height="10"
+   viewBox="0 0 10 10"
+   version="1.1"
+   id="svg1"
+   inkscape:version="1.4.2 (ebf0e940d0, 2025-05-08)"
+   sodipodi:docname="test.svg"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <sodipodi:namedview
+     id="namedview1"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:showpageshadow="2"
+     inkscape:pageopacity="0.0"
+     inkscape:pagecheckerboard="0"
+     inkscape:deskcolor="#d1d1d1"
+     inkscape:document-units="px"
+     inkscape:current-layer="layer1" />
+  <defs
+     id="defs1" />
+  <g
+     inkscape:label="Layer 1"
+     inkscape:groupmode="layer"
+     id="layer1">
+    <rect
+       style="fill:#ff0000;fill-rule:evenodd;"
+       id="rect1"
+       width="5"
+       height="5"
+       x="0"
+       y="0" />
+    <rect
+       style="opacity:0.5;fill:#ff0000;fill-rule:evenodd"
+       id="rect1-36"
+       width="5"
+       height="5"
+       x="5"
+       y="5" />
+    <rect
+       style="fill:#00ff00;fill-rule:evenodd"
+       id="rect1-3"
+       width="5"
+       height="5"
+       x="5"
+       y="0" />
+    <rect
+       style="fill:#0000ff;fill-rule:evenodd"
+       id="rect1-3-1"
+       width="5"
+       height="5"
+       x="0"
+       y="5" />
+  </g>
+</svg>
diff --git a/test/data/test.xpm b/test/data/test.xpm
new file mode 100644
index 0000000..12eb337
--- /dev/null
+++ b/test/data/test.xpm
@@ -0,0 +1,17 @@
+/* XPM */
+static char * test_xpm[] = {
+"10 10 4 1",
+" 	c None",
+".	c #FF0000",
+"+	c #00FF00",
+"@	c #0000FF",
+".....+++++",
+".....+++++",
+".....+++++",
+".....+++++",
+".....+++++",
+"@@@@@     ",
+"@@@@@     ",
+"@@@@@     ",
+"@@@@@     ",
+"@@@@@     "};
diff --git a/test/image_processor.cc b/test/image_processor.cc
new file mode 100644
index 0000000..c005f01
--- /dev/null
+++ b/test/image_processor.cc
@@ -0,0 +1,251 @@
+#include "image_processor.hh"
+
+#include "config.h"
+#include "image.hh"
+#include "image_loader.hh"
+#include "spawner.hh"
+
+#include <bit>
+#include <cmath>
+#include <cstdint>
+#include <filesystem>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <memory>
+#include <string>
+#include <utility>
+
+#ifndef TESTDIR
+# define TESTDIR "."
+#endif
+
+namespace {
+
+// JPEG compression at quality 90
+constexpr int kLossyError = 32;
+
+MATCHER_P(ColourLossyEq, expected, "") {
+  uint8_t a1 = arg >> 24;
+  uint8_t e1 = expected >> 24;
+  uint8_t a2 = arg >> 16;
+  uint8_t e2 = expected >> 16;
+  uint8_t a3 = arg >> 8;
+  uint8_t e3 = expected >> 8;
+  uint8_t a4 = arg;
+  uint8_t e4 = expected;
+  return abs(static_cast<int>(a1) - static_cast<int>(e1)) <= kLossyError &&
+      abs(static_cast<int>(a2) - static_cast<int>(e2)) <= kLossyError &&
+      abs(static_cast<int>(a3) - static_cast<int>(e3)) <= kLossyError &&
+      abs(static_cast<int>(a4) - static_cast<int>(e4)) <= kLossyError;
+}
+
+std::string error2str(ImageLoadError err) {
+  switch (err) {
+    case ImageLoadError::kNoSuchFile:
+      return "no such file";
+    case ImageLoadError::kError:
+      return "error";
+    case ImageLoadError::kUnsupportedFormat:
+      return "unsupported format";
+    case ImageLoadError::kProcessError:
+      return "process error";
+  }
+  std::unreachable();
+}
+
+class ImageProcessorTest : public testing::Test {
+ protected:
+  void SetUp() override {
+    {
+      auto spawner = Spawner::create();
+      ASSERT_TRUE(spawner.has_value());
+      spawner_ = std::move(spawner.value());
+    }
+
+    {
+      auto process = spawner_->run(Spawner::Exec::kImageProcessor);
+      ASSERT_TRUE(process.has_value());
+      process_ = std::move(process.value());
+    }
+  }
+
+  [[nodiscard]]
+  Process& process() const {
+    return *process_;
+  }
+
+  [[nodiscard]]
+  static std::filesystem::path testdir() {
+    return TESTDIR;
+  }
+
+  void peek(std::string const& name) {
+    auto ret = image_processor::peek(process(), testdir() / name);
+    ASSERT_TRUE(ret.has_value()) << error2str(ret.error());
+    EXPECT_EQ(10, ret->width);
+    EXPECT_EQ(10, ret->height);
+  }
+
+ private:
+  std::unique_ptr<Spawner> spawner_;
+  std::unique_ptr<Process> process_;
+};
+
+enum class AlphaMode : uint8_t {
+  kFull,
+  kMono,
+  kNone,
+};
+
+class ImageProcessorTestWithFormat : public ImageProcessorTest, public testing::WithParamInterface<Image::Format> {
+ protected:
+  void load(std::string const& name, AlphaMode alpha = AlphaMode::kFull, bool lossy = false) {
+    auto ret = image_processor::load(process(), testdir() / name, GetParam());
+    ASSERT_TRUE(ret.has_value()) << error2str(ret.error());
+    EXPECT_EQ(10, ret.value()->width());
+    EXPECT_EQ(10, ret.value()->height());
+    EXPECT_EQ(GetParam(), ret.value()->format());
+
+    EXPECT_GE(4 * ret.value()->width(), ret.value()->scanline());
+    if (lossy) {
+      for (uint32_t y = 0; y < ret.value()->height(); ++y) {
+        for (uint32_t x = 0; x < ret.value()->width(); ++x) {
+          EXPECT_THAT(reinterpret_cast<uint32_t const*>(
+              ret.value()->data() + (y * ret.value()->scanline()))[x],
+                      ColourLossyEq(expected_color(x, y, alpha)))
+              << x << "x" << y;
+        }
+      }
+    } else {
+      for (uint32_t y = 0; y < ret.value()->height(); ++y) {
+        for (uint32_t x = 0; x < ret.value()->width(); ++x) {
+          EXPECT_EQ(expected_color(x, y, alpha),
+                    reinterpret_cast<uint32_t const*>(
+                        ret.value()->data() + (y * ret.value()->scanline()))[x])
+              << x << "x" << y;
+        }
+      }
+    }
+  }
+
+ private:
+  static uint32_t expected_argb(uint32_t x, uint32_t y) {
+    uint32_t argb;
+    if (x < 5) {
+      if (y < 5) {
+        argb = 0xffff0000;
+      } else {
+        argb = 0xff0000ff;
+      }
+    } else {
+      if (y < 5) {
+        argb = 0xff00ff00;
+      } else {
+        argb = 0x80ff0000;
+      }
+    }
+    return argb;
+  }
+
+  static uint32_t argb_to_format(uint32_t argb) {
+    if constexpr (std::endian::native == std::endian::big) {
+      switch (GetParam()) {
+        case Image::Format::ARGB_8888:
+          return argb;
+        case Image::Format::BGRA_8888:
+          return std::byteswap(argb);
+        case Image::Format::RGBA_8888:
+          return std::rotl(argb, 8);
+        case Image::Format::ABGR_8888:
+          return std::byteswap(std::rotl(argb, 8));
+      }
+    } else {
+      switch (GetParam()) {
+        case Image::Format::ARGB_8888:
+          return std::byteswap(argb);
+        case Image::Format::BGRA_8888:
+          return argb;
+        case Image::Format::RGBA_8888:
+          return std::byteswap(std::rotl(argb, 8));
+        case Image::Format::ABGR_8888:
+          return std::rotl(argb, 8);
+      }
+    }
+    std::unreachable();
+  }
+
+  static uint32_t expected_color(uint32_t x, uint32_t y, AlphaMode alpha) {
+    uint32_t argb = expected_argb(x, y);
+    switch (alpha) {
+      case AlphaMode::kFull:
+        break;
+      case AlphaMode::kMono:
+        if (argb >> 24 != 0xff)
+          argb = 0;
+        break;
+      case AlphaMode::kNone:
+        argb |= 0xff000000;
+        break;
+    }
+    return argb_to_format(argb);
+  }
+
+  static uint32_t expected_color_no_alpha(uint32_t x, uint32_t y) {
+    return argb_to_format(0xff000000 | expected_argb(x, y));
+  }
+};
+
+}  // namespace
+
+TEST_F(ImageProcessorTest, peek_no_such_file) {
+  auto ret = image_processor::peek(process(), testdir() / "does_not_exist.png");
+  ASSERT_FALSE(ret.has_value());
+  EXPECT_EQ(ImageLoadError::kNoSuchFile, ret.error());
+}
+
+#if HAVE_PNG
+TEST_F(ImageProcessorTest, peek_png) {
+  peek("test.png");
+}
+
+TEST_P(ImageProcessorTestWithFormat, load_png) {
+  load("test.png");
+}
+#endif
+
+#if HAVE_JPEG
+TEST_F(ImageProcessorTest, peek_jpeg) {
+  peek("test.jpeg");
+}
+
+TEST_P(ImageProcessorTestWithFormat, load_jpeg) {
+  load("test.jpeg", AlphaMode::kNone, /* lossy */ true);
+}
+#endif
+
+#if HAVE_XPM
+TEST_F(ImageProcessorTest, peek_xpm) {
+  peek("test.xpm");
+}
+
+TEST_P(ImageProcessorTestWithFormat, load_xpm) {
+  load("test.xpm", AlphaMode::kMono);
+}
+#endif
+
+#if HAVE_RSVG
+TEST_F(ImageProcessorTest, peek_svg) {
+  peek("test.svg");
+}
+
+TEST_P(ImageProcessorTestWithFormat, load_svg) {
+  load("test.svg");
+}
+#endif
+
+INSTANTIATE_TEST_SUITE_P(ImageProcessor,
+                         ImageProcessorTestWithFormat,
+                         testing::Values(Image::Format::RGBA_8888,
+                                         Image::Format::ARGB_8888,
+                                         Image::Format::BGRA_8888,
+                                         Image::Format::ABGR_8888));
diff --git a/test/io.cc b/test/io.cc
new file mode 100644
index 0000000..39d558b
--- /dev/null
+++ b/test/io.cc
@@ -0,0 +1,274 @@
+#include "io.hh"
+
+#include "io_test_helper.hh"
+
+#include <cerrno>
+#include <dirent.h>
+#include <fcntl.h>
+#include <gtest/gtest.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <utility>
+
+namespace {
+
+bool remove_recursive(int fd) {
+  auto* dir = fdopendir(fd);
+  if (!dir)
+    return false;
+  while (auto* ent = readdir(dir)) {
+    if (ent->d_name[0] == '.') {
+      if (ent->d_name[1] == '\0')
+        continue;
+      if (ent->d_name[1] == '.' && ent->d_name[2] == '\0')
+        continue;
+    }
+    bool is_dir;
+    if (ent->d_type == DT_DIR) {
+      is_dir = true;
+    } else if (ent->d_type == DT_UNKNOWN) {
+      struct stat buf;
+      if (fstatat(dirfd(dir), ent->d_name, &buf, AT_SYMLINK_NOFOLLOW) == 0) {
+        is_dir = S_ISDIR(buf.st_mode);
+      } else {
+        if (errno != ENOENT) {
+          closedir(dir);
+          return false;
+        }
+        is_dir = false;
+      }
+    } else {
+      is_dir = false;
+    }
+
+    if (is_dir) {
+      int fd2 = openat(dirfd(dir), ent->d_name, O_RDONLY | O_DIRECTORY);
+      if (fd2 == -1) {
+        if (errno != ENOENT) {
+          closedir(dir);
+          return false;
+        }
+      } else {
+        if (!remove_recursive(fd2)) {
+          closedir(dir);
+          return false;
+        }
+      }
+    }
+    if (unlinkat(dirfd(dir), ent->d_name, is_dir ? AT_REMOVEDIR : 0)) {
+      if (errno != ENOENT) {
+        closedir(dir);
+        return false;
+      }
+    }
+  }
+  closedir(dir);
+  return true;
+}
+
+class IoTest : public testing::Test {
+ protected:
+  void SetUp() override {
+    // NOLINTNEXTLINE(misc-include-cleaner)
+    tmpdir_ = P_tmpdir "/jkc-test-io-XXXXXX";
+    // NOLINTNEXTLINE(misc-include-cleaner)
+    auto* ret = mkdtemp(tmpdir_.data());
+    ASSERT_EQ(ret, tmpdir_.data());
+    dirfd_ = open(tmpdir_.c_str(), O_PATH | O_DIRECTORY);
+    ASSERT_NE(-1, dirfd_);
+  }
+
+  void TearDown() override {
+    int fd = openat(dirfd_, ".", O_RDONLY | O_DIRECTORY);
+    EXPECT_NE(-1, fd);
+    if (fd != -1) {
+      EXPECT_TRUE(remove_recursive(fd));
+    }
+    close(dirfd_);
+    rmdir(tmpdir_.c_str());
+  }
+
+  [[nodiscard]] int dirfd() const { return dirfd_; }
+
+  void touch(const std::string& name, const std::string& value = "") {
+    auto ret = io::createat(dirfd(), name, false);
+    ASSERT_TRUE(ret.has_value());
+    auto ret2 = ret.value()->repeat_write(value.data(), value.size());
+    EXPECT_TRUE(ret2.has_value());
+    if (ret2.has_value()) {
+      EXPECT_EQ(ret2.value(), value.size());
+    }
+    EXPECT_TRUE(ret.value()->close().has_value());
+  }
+
+  void cat(const std::string& name, const std::string& value) {
+    auto ret = io::openat(dirfd(), name);
+    ASSERT_TRUE(ret.has_value());
+    std::string tmp(value.size(), ' ');
+    auto ret2 = ret.value()->repeat_read(tmp.data(), tmp.size());
+    ASSERT_TRUE(ret2.has_value());
+    EXPECT_EQ(value.size(), ret2.value());
+    EXPECT_EQ(tmp, value);
+    ret2 = ret.value()->repeat_read(tmp.data(), tmp.size());
+    ASSERT_FALSE(ret2.has_value());
+    EXPECT_EQ(io::ReadError::Eof, ret2.error());
+  }
+
+ private:
+  int dirfd_{-1};
+  std::string tmpdir_;
+};
+
+}  // namespace
+
+TEST_F(IoTest, no_such_file) {
+  auto ret = io::openat(dirfd(), "no-such-file");
+  ASSERT_FALSE(ret.has_value());
+  EXPECT_EQ(io::OpenError::NoSuchFile, ret.error());
+}
+
+TEST_F(IoTest, read_empty) {
+  touch("test");
+
+  auto ret = io::openat(dirfd(), "test");
+  ASSERT_TRUE(ret.has_value());
+  std::string tmp(10, ' ');
+  auto ret2 = ret.value()->read(tmp.data(), tmp.size());
+  ASSERT_FALSE(ret2.has_value());
+  EXPECT_EQ(io::ReadError::Eof, ret2.error());
+}
+
+TEST_F(IoTest, skip_empty) {
+  touch("test");
+
+  auto ret = io::openat(dirfd(), "test");
+  ASSERT_TRUE(ret.has_value());
+  auto ret2 = ret.value()->skip(10);
+  ASSERT_FALSE(ret2.has_value());
+  EXPECT_EQ(io::ReadError::Eof, ret2.error());
+}
+
+TEST_F(IoTest, read) {
+  touch("test", "hello world");
+
+  auto ret = io::openat(dirfd(), "test");
+  ASSERT_TRUE(ret.has_value());
+  std::string tmp(12, ' ');
+  auto ret2 = ret.value()->repeat_read(tmp.data(), tmp.size());
+  ASSERT_TRUE(ret2.has_value());
+  EXPECT_EQ(11, ret2.value());
+  tmp.resize(ret2.value());
+  EXPECT_EQ("hello world", tmp);
+}
+
+TEST_F(IoTest, skip) {
+  touch("test", "hello world");
+
+  auto ret = io::openat(dirfd(), "test");
+  ASSERT_TRUE(ret.has_value());
+  auto ret2 = ret.value()->repeat_skip(6);
+  ASSERT_TRUE(ret2.has_value());
+  EXPECT_EQ(6, ret2.value());
+  std::string tmp(12, ' ');
+  auto ret3 = ret.value()->repeat_read(tmp.data(), tmp.size());
+  ASSERT_TRUE(ret3.has_value());
+  EXPECT_EQ(5, ret3.value());
+  tmp.resize(ret3.value());
+  EXPECT_EQ("world", tmp);
+}
+
+TEST_F(IoTest, read_block) {
+  touch("test", "hello world");
+
+  auto ret = io::openat(dirfd(), "test");
+  ASSERT_TRUE(ret.has_value());
+  auto ret2 = io_make_max_block(std::move(ret.value()), 2);
+  std::string tmp(12, ' ');
+  auto ret3 = ret2->repeat_read(tmp.data(), tmp.size());
+  ASSERT_TRUE(ret3.has_value());
+  EXPECT_EQ(11, ret3.value());
+  tmp.resize(ret3.value());
+  EXPECT_EQ("hello world", tmp);
+}
+
+TEST_F(IoTest, skip_block) {
+  touch("test", "hello world");
+
+  auto ret = io::openat(dirfd(), "test");
+  ASSERT_TRUE(ret.has_value());
+  auto ret2 = io_make_max_block(std::move(ret.value()), 2);
+  auto ret3 = ret2->repeat_skip(6);
+  ASSERT_TRUE(ret3.has_value());
+  EXPECT_EQ(6, ret3.value());
+  std::string tmp(12, ' ');
+  auto ret4 = ret2->repeat_read(tmp.data(), tmp.size());
+  ASSERT_TRUE(ret4.has_value());
+  EXPECT_EQ(5, ret4.value());
+  tmp.resize(ret4.value());
+  EXPECT_EQ("world", tmp);
+}
+
+TEST_F(IoTest, create) {
+  auto ret = io::createat(dirfd(), "test", false);
+  ASSERT_TRUE(ret.has_value());
+  std::string tmp{"hello world"};
+  auto ret2 = ret.value()->repeat_write(tmp.data(), tmp.size());
+  ASSERT_TRUE(ret2.has_value());
+  EXPECT_EQ(11, ret2.value());
+  EXPECT_TRUE(ret.value()->close().has_value());
+
+  cat("test", "hello world");
+}
+
+TEST_F(IoTest, create_exists) {
+  touch("test");
+
+  auto ret = io::createat(dirfd(), "test", false);
+  ASSERT_FALSE(ret.has_value());
+  EXPECT_EQ(io::CreateError::Exists, ret.error());
+}
+
+TEST_F(IoTest, create_overwrite) {
+  touch("test");
+
+  auto ret = io::createat(dirfd(), "test", true);
+  ASSERT_TRUE(ret.has_value());
+  std::string tmp{"hello world"};
+  auto ret2 = ret.value()->repeat_write(tmp.data(), tmp.size());
+  ASSERT_TRUE(ret2.has_value());
+  EXPECT_EQ(11, ret2.value());
+  EXPECT_TRUE(ret.value()->close().has_value());
+
+  cat("test", "hello world");
+}
+
+TEST_F(IoTest, write_block) {
+  auto ret = io::createat(dirfd(), "test", false);
+  ASSERT_TRUE(ret.has_value());
+  auto ret2 = io_make_max_block(std::move(ret.value()), 2);
+  std::string tmp{"hello world"};
+  auto ret3 = ret2->repeat_write(tmp.data(), tmp.size());
+  ASSERT_TRUE(ret3.has_value());
+  EXPECT_EQ(11, ret3.value());
+  EXPECT_TRUE(ret2->close().has_value());
+
+  cat("test", "hello world");
+}
+
+TEST_F(IoTest, pipe) {
+  auto ret = io::pipe();
+  ASSERT_TRUE(ret.has_value());
+
+  std::string tmp{"hello world"};
+  auto ret2 = ret.value().second->repeat_write(tmp.data(), tmp.size());
+  ASSERT_TRUE(ret2.has_value());
+  EXPECT_EQ(11, ret2.value());
+  ret.value().second.reset();
+
+  std::string tmp2(12, ' ');
+  auto ret3 = ret.value().first->repeat_read(tmp2.data(), tmp2.size());
+  ASSERT_TRUE(ret3.has_value());
+  EXPECT_EQ(11, ret3.value());
+  tmp2.resize(ret3.value());
+  EXPECT_EQ(tmp, tmp2);
+}
diff --git a/test/io_test_helper.cc b/test/io_test_helper.cc
new file mode 100644
index 0000000..880a114
--- /dev/null
+++ b/test/io_test_helper.cc
@@ -0,0 +1,165 @@
+#include "io_test_helper.hh"
+
+#include "io.hh"
+
+#include <algorithm>
+#include <cstddef>
+#include <expected>
+#include <memory>
+#include <utility>
+
+namespace {
+
+class BreakingReader : public io::Reader {
+ public:
+  BreakingReader(std::unique_ptr<io::Reader> reader, size_t offset,
+                 io::ReadError error)
+      : reader_(std::move(reader)), offset_(offset), error_(error) {}
+
+  [[nodiscard]]
+  std::expected<size_t, io::ReadError> read(void* dst, size_t max) override {
+    if (offset_ == 0)
+      return std::unexpected(error_);
+    size_t avail = std::min(offset_, max);
+    auto ret = reader_->read(dst, avail);
+    if (ret.has_value()) {
+      offset_ -= ret.value();
+    }
+    return ret;
+  }
+
+  [[nodiscard]]
+  std::expected<size_t, io::ReadError> skip(size_t max) override {
+    if (offset_ == 0)
+      return std::unexpected(error_);
+    size_t avail = std::min(offset_, max);
+    auto ret = reader_->skip(avail);
+    if (ret.has_value()) {
+      offset_ -= ret.value();
+    }
+    return ret;
+  }
+
+  [[nodiscard]]
+  int raw_fd() const override {
+    return reader_->raw_fd();
+  }
+
+ private:
+  std::unique_ptr<io::Reader> reader_;
+  size_t offset_;
+  io::ReadError const error_;
+};
+
+class BreakingWriter : public io::Writer {
+ public:
+  BreakingWriter(std::unique_ptr<io::Writer> writer, size_t offset,
+                 io::WriteError error)
+      : writer_(std::move(writer)), offset_(offset), error_(error) {}
+
+  [[nodiscard]]
+  std::expected<size_t, io::WriteError> write(void const* dst,
+                                              size_t size) override {
+    if (offset_ == 0)
+      return std::unexpected(error_);
+    size_t avail = std::min(offset_, size);
+    auto ret = writer_->write(dst, avail);
+    if (ret.has_value()) {
+      offset_ -= ret.value();
+    }
+    return ret;
+  }
+
+  [[nodiscard]]
+  std::expected<void, io::WriteError> close() override {
+    return writer_->close();
+  }
+
+  [[nodiscard]]
+  int raw_fd() const override {
+    return writer_->raw_fd();
+  }
+
+ private:
+  std::unique_ptr<io::Writer> writer_;
+  size_t offset_;
+  io::WriteError const error_;
+};
+
+class MaxBlockReader : public io::Reader {
+ public:
+  MaxBlockReader(std::unique_ptr<io::Reader> reader, size_t max_block_size)
+      : reader_(std::move(reader)), max_block_size_(max_block_size) {}
+
+  [[nodiscard]]
+  std::expected<size_t, io::ReadError> read(void* dst, size_t max) override {
+    size_t avail = std::min(max_block_size_, max);
+    return reader_->read(dst, avail);
+  }
+
+  [[nodiscard]]
+  std::expected<size_t, io::ReadError> skip(size_t max) override {
+    size_t avail = std::min(max_block_size_, max);
+    return reader_->skip(avail);
+  }
+
+  [[nodiscard]]
+  int raw_fd() const override {
+    return reader_->raw_fd();
+  }
+
+ private:
+  std::unique_ptr<io::Reader> reader_;
+  size_t const max_block_size_;
+};
+
+class MaxBlockWriter : public io::Writer {
+ public:
+  MaxBlockWriter(std::unique_ptr<io::Writer> writer, size_t max_block_size)
+      : writer_(std::move(writer)), max_block_size_(max_block_size) {}
+
+  [[nodiscard]]
+  std::expected<size_t, io::WriteError> write(void const* dst,
+                                              size_t size) override {
+    size_t avail = std::min(max_block_size_, size);
+    return writer_->write(dst, avail);
+  }
+
+  [[nodiscard]]
+  std::expected<void, io::WriteError> close() override {
+    return writer_->close();
+  }
+
+  [[nodiscard]]
+  int raw_fd() const override {
+    return writer_->raw_fd();
+  }
+
+ private:
+  std::unique_ptr<io::Writer> writer_;
+  size_t const max_block_size_;
+};
+
+}  // namespace
+
+std::unique_ptr<io::Reader> io_make_breaking(std::unique_ptr<io::Reader> reader,
+                                             size_t offset,
+                                             io::ReadError error) {
+  return std::make_unique<BreakingReader>(std::move(reader), offset, error);
+}
+
+std::unique_ptr<io::Writer> io_make_breaking(std::unique_ptr<io::Writer> writer,
+                                             size_t offset,
+                                             io::WriteError error) {
+  return std::make_unique<BreakingWriter>(std::move(writer), offset, error);
+}
+
+std::unique_ptr<io::Reader> io_make_max_block(
+    std::unique_ptr<io::Reader> reader, size_t max_block_size) {
+  return std::make_unique<MaxBlockReader>(std::move(reader), max_block_size);
+}
+
+std::unique_ptr<io::Writer> io_make_max_block(
+    std::unique_ptr<io::Writer> writer, size_t max_block_size) {
+  return std::make_unique<MaxBlockWriter>(std::move(writer), max_block_size);
+}
diff --git a/test/io_test_helper.hh b/test/io_test_helper.hh
new file mode 100644
index 0000000..eb7bbb3
--- /dev/null
+++ b/test/io_test_helper.hh
@@ -0,0 +1,27 @@
+#ifndef IO_TEST_HELPER_HH
+#define IO_TEST_HELPER_HH
+
+#include "io.hh"  // IWYU pragma: export
+
+#include <cstddef>
+#include <memory>
+
+[[nodiscard]]
+std::unique_ptr<io::Reader> io_make_breaking(
+    std::unique_ptr<io::Reader> reader, size_t offset = 0,
+    io::ReadError error = io::ReadError::Error);
+
+[[nodiscard]]
+std::unique_ptr<io::Writer> io_make_breaking(
+    std::unique_ptr<io::Writer> writer, size_t offset = 0,
+    io::WriteError error = io::WriteError::Error);
+
+[[nodiscard]]
+std::unique_ptr<io::Reader> io_make_max_block(
+    std::unique_ptr<io::Reader> reader, size_t max_block_size);
+
+[[nodiscard]]
+std::unique_ptr<io::Writer> io_make_max_block(
+    std::unique_ptr<io::Writer> writer, size_t max_block_size);
+
+#endif  // IO_TEST_HELPER_HH
diff --git a/test/line.cc b/test/line.cc
new file mode 100644
index 0000000..e0ea002
--- /dev/null
+++ b/test/line.cc
@@ -0,0 +1,182 @@
+#include "line.hh"
+
+#include "io_test_helper.hh"
+
+#include <cstddef>
+#include <gtest/gtest.h>
+#include <limits>
+#include <utility>
+
+TEST(line, empty) {
+  auto reader = line::open(io::memory(""));
+  EXPECT_EQ(0, reader->number());
+  auto line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+  EXPECT_EQ(0, reader->number());
+}
+
+TEST(line, one_line) {
+  auto reader = line::open(io::memory("foo"));
+  EXPECT_EQ(0, reader->number());
+  auto line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("foo", line.value());
+  EXPECT_EQ(1, reader->number());
+  line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+  EXPECT_EQ(1, reader->number());
+}
+
+TEST(line, many_lines) {
+  auto reader = line::open(io::memory("foo\nbar\nfoobar\n"));
+  EXPECT_EQ(0, reader->number());
+  auto line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("foo", line.value());
+  EXPECT_EQ(1, reader->number());
+  line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("bar", line.value());
+  EXPECT_EQ(2, reader->number());
+  line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("foobar", line.value());
+  EXPECT_EQ(3, reader->number());
+  line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+  EXPECT_EQ(3, reader->number());
+}
+
+TEST(line, many_lines_mixed) {
+  auto reader = line::open(io::memory("foo\r\nbar\rfoobar\n"));
+  EXPECT_EQ(0, reader->number());
+  auto line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("foo", line.value());
+  EXPECT_EQ(1, reader->number());
+  line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("bar", line.value());
+  EXPECT_EQ(2, reader->number());
+  line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("foobar", line.value());
+  EXPECT_EQ(3, reader->number());
+  line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+  EXPECT_EQ(3, reader->number());
+}
+
+TEST(line, empty_line) {
+  auto reader = line::open(io::memory("\n"));
+  EXPECT_EQ(0, reader->number());
+  auto line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("", line.value());
+  EXPECT_EQ(1, reader->number());
+  line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+  EXPECT_EQ(1, reader->number());
+}
+
+TEST(line, max_line) {
+  auto reader = line::open(io::memory("012345678901234567890123456789"), 10);
+  EXPECT_EQ(0, reader->number());
+  auto line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("0123456789", line.value());
+  EXPECT_EQ(1, reader->number());
+  line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("0123456789", line.value());
+  EXPECT_EQ(2, reader->number());
+  line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("0123456789", line.value());
+  EXPECT_EQ(3, reader->number());
+  line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+  EXPECT_EQ(3, reader->number());
+}
+
+TEST(line, read_error) {
+  auto reader = line::open(
+      io_make_breaking(io::memory("foo bar fum\nfim zam"), /* offset */ 5));
+  auto line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Error, line.error());
+}
+
+TEST(line, read_error_newline) {
+  auto reader = line::open(
+      io_make_breaking(io::memory("foo bar\r\nfim zam"), /* offset */ 8));
+  auto line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Error, line.error());
+}
+
+TEST(line, blocky) {
+  auto reader = line::open(io_make_max_block(io::memory("foo bar\r\nfim zam"),
+                                             /* max_block_size */ 1));
+  auto line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("foo bar", line.value());
+  line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("fim zam", line.value());
+  line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+}
+
+TEST(line, blocky_newline) {
+  auto reader = line::open(io_make_max_block(io::memory("foo bar\r\nfim zam"),
+                                             /* max_block_size */ 8));
+  auto line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("foo bar", line.value());
+  line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("fim zam", line.value());
+  line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+}
+
+TEST(line, eof_newline) {
+  auto reader = line::open(io::memory("foo bar\r"));
+  auto line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("foo bar", line.value());
+  line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+}
+
+TEST(line, max_newline) {
+  auto reader = line::open(io::memory("foo bar\r"), 6);
+  auto line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("foo ba", line.value());
+  line = reader->read();
+  ASSERT_TRUE(line.has_value());
+  EXPECT_EQ("r", line.value());
+  line = reader->read();
+  ASSERT_FALSE(line.has_value());
+  EXPECT_EQ(io::ReadError::Eof, line.error());
+}
+
+TEST(line, max_line_overflow) {
+  EXPECT_DEATH_IF_SUPPORTED(
+      {
+        std::ignore =
+            line::open(io::memory(""), std::numeric_limits<size_t>::max());
+      },
+      "");
+}
diff --git a/test/paths.cc b/test/paths.cc
new file mode 100644
index 0000000..b07e459
--- /dev/null
+++ b/test/paths.cc
@@ -0,0 +1,63 @@
+#include "paths.hh"
+
+#include "testenv.hh"
+
+#include <gtest/gtest.h>
+
+namespace {
+
+class PathsTest : public TestEnv {};
+
+}  // namespace
+
+TEST_F(PathsTest, home) {
+  setenv("HOME", "foo-bar");
+  EXPECT_EQ("foo-bar", paths::home());
+  unsetenv("HOME");
+  EXPECT_NE("foo-bar", paths::home());
+  setenv("HOME", "");
+  EXPECT_NE("", paths::home());
+}
+
+TEST_F(PathsTest, config_dirs) {
+  setenv("XDG_CONFIG_HOME", "foo");
+  setenv("XDG_CONFIG_DIRS", "bar:fum::foo");
+  auto dirs = paths::config_dirs();
+  EXPECT_EQ(3, dirs.size());
+  if (dirs.size() >= 3) {
+    EXPECT_EQ("foo", dirs[0]);
+    EXPECT_EQ("bar", dirs[1]);
+    EXPECT_EQ("fum", dirs[2]);
+  }
+  setenv("HOME", "home");
+  unsetenv("XDG_CONFIG_HOME");
+  unsetenv("XDG_CONFIG_DIRS");
+  dirs = paths::config_dirs();
+  EXPECT_EQ(2, dirs.size());
+  if (dirs.size() >= 2) {
+    EXPECT_EQ("home/.config", dirs[0]);
+    EXPECT_EQ("/etc/xdg", dirs[1]);
+  }
+}
+
+TEST_F(PathsTest, data_dirs) {
+  setenv("XDG_DATA_HOME", "foo");
+  setenv("XDG_DATA_DIRS", "bar:fum::foo");
+  auto dirs = paths::data_dirs();
+  EXPECT_EQ(3, dirs.size());
+  if (dirs.size() >= 3) {
+    EXPECT_EQ("foo", dirs[0]);
+    EXPECT_EQ("bar", dirs[1]);
+    EXPECT_EQ("fum", dirs[2]);
+  }
+  setenv("HOME", "home");
+  unsetenv("XDG_DATA_HOME");
+  unsetenv("XDG_DATA_DIRS");
+  dirs = paths::data_dirs();
+  EXPECT_EQ(3, dirs.size());
+  if (dirs.size() >= 3) {
+    EXPECT_EQ("home/.local/share", dirs[0]);
+    EXPECT_EQ("/usr/local/share/", dirs[1]);
+    EXPECT_EQ("/usr/share/", dirs[2]);
+  }
+}
diff --git a/test/str.cc b/test/str.cc
new file mode 100644
index 0000000..0184ad5
--- /dev/null
+++ b/test/str.cc
@@ -0,0 +1,164 @@
+#include "str.hh"
+
+#include <gtest/gtest.h>
+
+TEST(str, split) {
+  auto ret = str::split("");
+  EXPECT_EQ(0, ret.size());
+
+  ret = str::split("", ' ', true);
+  ASSERT_EQ(1, ret.size());
+  EXPECT_EQ("", ret[0]);
+
+  ret = str::split(" ");
+  EXPECT_EQ(0, ret.size());
+
+  ret = str::split(" ", ' ', true);
+  ASSERT_EQ(2, ret.size());
+  EXPECT_EQ("", ret[0]);
+  EXPECT_EQ("", ret[1]);
+
+  ret = str::split(" a b ");
+  ASSERT_EQ(2, ret.size());
+  EXPECT_EQ("a", ret[0]);
+  EXPECT_EQ("b", ret[1]);
+
+  ret = str::split(" a b ", ' ', true);
+  ASSERT_EQ(4, ret.size());
+  EXPECT_EQ("", ret[0]);
+  EXPECT_EQ("a", ret[1]);
+  EXPECT_EQ("b", ret[2]);
+  EXPECT_EQ("", ret[3]);
+
+  ret = str::split(" a b", ' ', true);
+  ASSERT_EQ(3, ret.size());
+  EXPECT_EQ("", ret[0]);
+  EXPECT_EQ("a", ret[1]);
+  EXPECT_EQ("b", ret[2]);
+}
+
+TEST(str, split2) {
+  auto ret = str::split("", "\r\n");
+  EXPECT_EQ(0, ret.size());
+
+  ret = str::split("", "\r\n", true);
+  ASSERT_EQ(1, ret.size());
+  EXPECT_EQ("", ret[0]);
+
+  ret = str::split("\r\n", "\r\n");
+  EXPECT_EQ(0, ret.size());
+
+  ret = str::split("\r\n", "\r\n", true);
+  ASSERT_EQ(2, ret.size());
+  EXPECT_EQ("", ret[0]);
+  EXPECT_EQ("", ret[1]);
+
+  ret = str::split("\r\na\r\nb\r\n", "\r\n");
+  ASSERT_EQ(2, ret.size());
+  EXPECT_EQ("a", ret[0]);
+  EXPECT_EQ("b", ret[1]);
+
+  ret = str::split("\r\na\r\nb\r\n", "\r\n", true);
+  ASSERT_EQ(4, ret.size());
+  EXPECT_EQ("", ret[0]);
+  EXPECT_EQ("a", ret[1]);
+  EXPECT_EQ("b", ret[2]);
+  EXPECT_EQ("", ret[3]);
+
+  ret = str::split("\r\na\r\nb", "\r\n", true);
+  ASSERT_EQ(3, ret.size());
+  EXPECT_EQ("", ret[0]);
+  EXPECT_EQ("a", ret[1]);
+  EXPECT_EQ("b", ret[2]);
+
+  ret = str::split("\ra\nb", "\r\n");
+  ASSERT_EQ(1, ret.size());
+  EXPECT_EQ("\ra\nb", ret[0]);
+}
+
+TEST(str, trim) {
+  auto ret = str::trim("");
+  EXPECT_EQ("", ret);
+
+  ret = str::trim(" ");
+  EXPECT_EQ("", ret);
+
+  ret = str::trim("  ");
+  EXPECT_EQ("", ret);
+
+  ret = str::trim("foo");
+  EXPECT_EQ("foo", ret);
+
+  ret = str::trim(" foo");
+  EXPECT_EQ("foo", ret);
+
+  ret = str::trim(" foo ");
+  EXPECT_EQ("foo", ret);
+
+  ret = str::trim("foo ");
+  EXPECT_EQ("foo", ret);
+
+  ret = str::trim("  foo bar           ");
+  EXPECT_EQ("foo bar", ret);
+
+  ret = str::trim("\tfoo bar\r\n");
+  EXPECT_EQ("foo bar", ret);
+}
+
+TEST(str, ltrim) {
+  auto ret = str::ltrim("");
+  EXPECT_EQ("", ret);
+
+  ret = str::ltrim(" ");
+  EXPECT_EQ("", ret);
+
+  ret = str::ltrim("  ");
+  EXPECT_EQ("", ret);
+
+  ret = str::ltrim("foo");
+  EXPECT_EQ("foo", ret);
+
+  ret = str::ltrim(" foo");
+  EXPECT_EQ("foo", ret);
+
+  ret = str::ltrim(" foo ");
+  EXPECT_EQ("foo ", ret);
+
+  ret = str::ltrim("foo ");
+  EXPECT_EQ("foo ", ret);
+
+  ret = str::ltrim("  foo bar           ");
+  EXPECT_EQ("foo bar           ", ret);
+
+  ret = str::ltrim("\tfoo bar\r\n");
+  EXPECT_EQ("foo bar\r\n", ret);
+}
+
+TEST(str, rtrim) {
+  auto ret = str::rtrim("");
+  EXPECT_EQ("", ret);
+
+  ret = str::rtrim(" ");
+  EXPECT_EQ("", ret);
+
+  ret = str::rtrim("  ");
+  EXPECT_EQ("", ret);
+
+  ret = str::rtrim("foo");
+  EXPECT_EQ("foo", ret);
+
+  ret = str::rtrim(" foo");
+  EXPECT_EQ(" foo", ret);
+
+  ret = str::rtrim(" foo ");
+  EXPECT_EQ(" foo", ret);
+
+  ret = str::rtrim("foo ");
+  EXPECT_EQ("foo", ret);
+
+  ret = str::rtrim("  foo bar           ");
+  EXPECT_EQ("  foo bar", ret);
+
+  ret = str::rtrim("\tfoo bar\r\n");
+  EXPECT_EQ("\tfoo bar", ret);
+}
diff --git a/test/testdir.cc b/test/testdir.cc
new file mode 100644
index 0000000..d5aef22
--- /dev/null
+++ b/test/testdir.cc
@@ -0,0 +1,37 @@
+#include "testdir.hh"
+
+#include <cstdlib>
+#include <filesystem>
+#include <format>
+#include <gtest/gtest.h>
+#include <system_error>
+
+namespace {
+
+std::filesystem::path mktmpdir() {
+  std::error_code ec;
+  auto base = std::filesystem::temp_directory_path(ec);
+  if (ec)
+    return {};
+  for (int i = 0; i < 10; ++i) {
+    auto name = std::format(
+        "{}-{}",
+        ::testing::UnitTest::GetInstance()->current_test_info()->name(),
+        rand());
+    auto tmpdir = base / name;
+    if (std::filesystem::exists(tmpdir))
+      continue;
+    if (std::filesystem::create_directory(tmpdir, ec))
+      return tmpdir;
+  }
+  return {};
+}
+
+}  // namespace
+
+TestDir::TestDir() : path_(mktmpdir()) {}
+
+TestDir::~TestDir() {
+  if (!path_.empty())
+    std::filesystem::remove_all(path_);
+}
diff --git a/test/testdir.hh b/test/testdir.hh
new file mode 100644
index 0000000..b59e09a
--- /dev/null
+++ b/test/testdir.hh
@@ -0,0 +1,22 @@
+#ifndef TESTDIR_HH
+#define TESTDIR_HH
+
+#include <filesystem>  // IWYU pragma: export
+
+class TestDir {
+ public:
+  TestDir();
+  ~TestDir();
+
+  TestDir(TestDir const&) = delete;
+  TestDir& operator=(TestDir const&) = delete;
+
+  bool good() const { return !path_.empty(); };
+
+  std::filesystem::path const& path() const { return path_; };
+
+ private:
+  std::filesystem::path path_;
+};
+
+#endif  // TESTDIR_HH
diff --git a/test/testenv.cc b/test/testenv.cc
new file mode 100644
index 0000000..56701a4
--- /dev/null
+++ b/test/testenv.cc
@@ -0,0 +1,44 @@
+#include "testenv.hh"
+
+#include <cstdlib>
+#include <optional>
+#include <string>
+
+void TestEnv::setenv(std::string const& name, std::string const& value) {
+  saveenv(name);
+
+  // NOLINTNEXTLINE(misc-include-cleaner)
+  ::setenv(name.c_str(), value.c_str(), 1);
+}
+
+void TestEnv::unsetenv(std::string const& name) {
+  saveenv(name);
+
+  // NOLINTNEXTLINE(misc-include-cleaner)
+  ::unsetenv(name.c_str());
+}
+
+void TestEnv::TearDown() {
+  for (auto const& pair : env_) {
+    if (pair.second.has_value()) {
+      // NOLINTNEXTLINE(misc-include-cleaner)
+      ::setenv(pair.first.c_str(), pair.second->c_str(), 1);
+    } else {
+      // NOLINTNEXTLINE(misc-include-cleaner)
+      ::unsetenv(pair.first.c_str());
+    }
+  }
+}
+
+void TestEnv::saveenv(std::string const& name) {
+  auto it = env_.find(name);
+  if (it != env_.end())
+    return;
+
+  auto* str = getenv(name.c_str());
+  if (str == nullptr) {
+    env_.emplace(name, std::nullopt);
+  } else {
+    env_.emplace(name, str);
+  }
+}
diff --git a/test/testenv.hh b/test/testenv.hh
new file mode 100644
index 0000000..abe0bc8
--- /dev/null
+++ b/test/testenv.hh
@@ -0,0 +1,22 @@
+#ifndef TESTENV_HH
+#define TESTENV_HH
+
+#include <gtest/gtest.h>
+#include <map>
+#include <optional>
+#include <string>
+
+class TestEnv : public testing::Test {
+ protected:
+  void setenv(std::string const& name, std::string const& value);
+  void unsetenv(std::string const& name);
+
+  void TearDown() override;
+
+ private:
+  void saveenv(std::string const& name);
+
+  std::map<std::string, std::optional<std::string>> env_;
+};
+
+#endif  // TESTENV_HH
diff --git a/test/u8.cc b/test/u8.cc
new file mode 100644
index 0000000..4378d9c
--- /dev/null
+++ b/test/u8.cc
@@ -0,0 +1,276 @@
+#include "u8.hh"
+
+#include <gtest/gtest.h>
+#include <iterator>
+#include <vector>
+
+TEST(u8, empty) {
+  std::vector<uint8_t> empty;
+  auto it = empty.begin();
+  auto ret = u8::read(it, empty.end());
+  ASSERT_FALSE(ret.has_value());
+  EXPECT_EQ(u::ReadError::End, ret.error());
+
+  auto ret_replace = u8::read_replace(it, empty.end(), false);
+  ASSERT_FALSE(ret_replace.has_value());
+  EXPECT_EQ(u::ReadErrorReplace::End, ret_replace.error());
+
+  EXPECT_FALSE(u8::write(it, empty.end(), 0x40));
+
+  EXPECT_FALSE(u8::skip(it, empty.end()));
+}
+
+TEST(u8, examples) {
+  {
+    std::vector<uint8_t> literal{0x57};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_TRUE(ret.has_value());
+    EXPECT_EQ(0x57, *ret);
+    EXPECT_EQ(it, literal.end());
+
+    it = literal.begin();
+    EXPECT_TRUE(u8::skip(it, literal.end()));
+    EXPECT_EQ(it, literal.end());
+  }
+  {
+    std::vector<uint8_t> literal{0xce, 0x92};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_TRUE(ret.has_value());
+    EXPECT_EQ(0x392, *ret);
+    EXPECT_EQ(it, literal.end());
+
+    it = literal.begin();
+    EXPECT_TRUE(u8::skip(it, literal.end()));
+    EXPECT_EQ(it, literal.end());
+  }
+  {
+    std::vector<uint8_t> literal{0xec, 0x9c, 0x84};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_TRUE(ret.has_value());
+    EXPECT_EQ(0xc704, *ret);
+    EXPECT_EQ(it, literal.end());
+
+    it = literal.begin();
+    EXPECT_TRUE(u8::skip(it, literal.end()));
+    EXPECT_EQ(it, literal.end());
+  }
+  {
+    std::vector<uint8_t> literal{0xf0, 0x90, 0x8d, 0x85};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_TRUE(ret.has_value());
+    EXPECT_EQ(0x10345, *ret);
+    EXPECT_EQ(it, literal.end());
+
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0x10345, *ret_replace);
+    EXPECT_EQ(it, literal.end());
+
+    it = literal.begin();
+    EXPECT_TRUE(u8::skip(it, literal.end()));
+    EXPECT_EQ(it, literal.end());
+  }
+  {
+    std::vector<uint8_t> literal(1, 0x0);
+    auto it = literal.begin();
+    EXPECT_TRUE(u8::write(it, literal.end(), 0x57));
+    EXPECT_EQ(0x57, literal[0]);
+    EXPECT_EQ(it, literal.end());
+  }
+  {
+    std::vector<uint8_t> literal(2, 0x0);
+    auto it = literal.begin();
+    EXPECT_TRUE(u8::write(it, literal.end(), 0x392));
+    EXPECT_EQ(0xce, literal[0]);
+    EXPECT_EQ(0x92, literal[1]);
+    EXPECT_EQ(it, literal.end());
+  }
+  {
+    std::vector<uint8_t> literal(3, 0x0);
+    auto it = literal.begin();
+    EXPECT_TRUE(u8::write(it, literal.end(), 0xc704));
+    EXPECT_EQ(0xec, literal[0]);
+    EXPECT_EQ(0x9c, literal[1]);
+    EXPECT_EQ(0x84, literal[2]);
+    EXPECT_EQ(it, literal.end());
+  }
+  {
+    std::vector<uint8_t> literal(4, 0x0);
+    auto it = literal.begin();
+    EXPECT_TRUE(u8::write(it, literal.end(), 0x10345));
+    EXPECT_EQ(0xf0, literal[0]);
+    EXPECT_EQ(0x90, literal[1]);
+    EXPECT_EQ(0x8d, literal[2]);
+    EXPECT_EQ(0x85, literal[3]);
+    EXPECT_EQ(it, literal.end());
+  }
+}
+
+TEST(u8, overlong) {
+  {
+    std::vector<uint8_t> literal{0xc0, 0x80};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Invalid, ret.error());
+  }
+}
+
+TEST(u8, incomplete) {
+  {
+    std::vector<uint8_t> literal{0xce};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Incomplete, ret.error());
+  }
+  {
+    std::vector<uint8_t> literal{0xec};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Incomplete, ret.error());
+  }
+  {
+    std::vector<uint8_t> literal{0xec, 0x9c};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Incomplete, ret.error());
+
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_FALSE(ret_replace.has_value());
+    EXPECT_EQ(u::ReadErrorReplace::Incomplete, ret_replace.error());
+
+    it = literal.begin();
+    ret_replace = u8::read_replace(it, literal.end(), true);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0xfffd, ret_replace.value());
+  }
+  {
+    std::vector<uint8_t> literal{0xf0};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Incomplete, ret.error());
+  }
+  {
+    std::vector<uint8_t> literal{0xf0, 0x90};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Incomplete, ret.error());
+  }
+  {
+    std::vector<uint8_t> literal{0xf0, 0x90, 0x8d};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Incomplete, ret.error());
+  }
+}
+
+TEST(u8, invalid) {
+  {
+    std::vector<uint8_t> literal{0xf0, 0xf0, 0xf0, 0xf0};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Invalid, ret.error());
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0xfffd, *ret_replace);
+    EXPECT_EQ(it, std::next(literal.begin()));
+  }
+  {
+    std::vector<uint8_t> literal{0xa0};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Invalid, ret.error());
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0xfffd, *ret_replace);
+    EXPECT_EQ(it, std::next(literal.begin()));
+  }
+  {
+    std::vector<uint8_t> literal{0xce, 0xff};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Invalid, ret.error());
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0xfffd, *ret_replace);
+    EXPECT_EQ(it, std::next(literal.begin()));
+  }
+  {
+    std::vector<uint8_t> literal{0xec, 0xff, 0x84};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Invalid, ret.error());
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0xfffd, *ret_replace);
+    EXPECT_EQ(it, std::next(literal.begin()));
+  }
+  {
+    std::vector<uint8_t> literal{0xec, 0x9c, 0xff};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Invalid, ret.error());
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0xfffd, *ret_replace);
+    EXPECT_EQ(it, std::next(literal.begin()));
+  }
+  {
+    std::vector<uint8_t> literal{0xf0, 0xff, 0x8d, 0x85};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Invalid, ret.error());
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0xfffd, *ret_replace);
+    EXPECT_EQ(it, std::next(literal.begin()));
+  }
+  {
+    std::vector<uint8_t> literal{0xf0, 0x90, 0xff, 0x85};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Invalid, ret.error());
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0xfffd, *ret_replace);
+    EXPECT_EQ(it, std::next(literal.begin()));
+  }
+  {
+    std::vector<uint8_t> literal{0xf0, 0x90, 0x8d, 0xff};
+    auto it = literal.begin();
+    auto ret = u8::read(it, literal.end());
+    ASSERT_FALSE(ret.has_value());
+    EXPECT_EQ(u::ReadError::Invalid, ret.error());
+    it = literal.begin();
+    auto ret_replace = u8::read_replace(it, literal.end(), false);
+    ASSERT_TRUE(ret_replace.has_value());
+    EXPECT_EQ(0xfffd, *ret_replace);
+    EXPECT_EQ(it, std::next(literal.begin()));
+  }
+}
-- 
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