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

---
 src/io.hh | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 src/io.hh

(limited to 'src/io.hh')

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
-- 
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