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#include "decompress.hh"
#include "buffer.hh"
#define ZLIB_CONST
#include <zlib.h>
#include <algorithm>
#include <cstddef>
#include <expected>
#include <limits>
#include <memory>
#include <optional>
#include <utility>
namespace decompress {
namespace {
const size_t kBufferSizeZ = static_cast<size_t>(1024) * 1024;
class DecompressReader : public io::Reader {
public:
DecompressReader(std::unique_ptr<io::Reader> reader, bool gzip)
: reader_(std::move(reader)), gzip_(gzip) {}
~DecompressReader() override {
if (initialized_)
inflateEnd(&stream_);
}
std::expected<size_t, io::ReadError> read(void* dst, size_t max) override {
auto err = fill();
if (err.has_value())
return std::unexpected(err.value());
// NOLINTNEXTLINE(misc-include-cleaner)
stream_.next_out = reinterpret_cast<Bytef*>(dst);
stream_.avail_out = max;
if (!initialized_) {
if (in_eof_ && buffer_->empty())
return 0;
stream_.zalloc = Z_NULL;
stream_.zfree = Z_NULL;
stream_.opaque = Z_NULL;
if (inflateInit2(&stream_, gzip_ ? 16 : 0) != Z_OK) {
return std::unexpected(io::ReadError::Error);
}
initialized_ = true;
}
auto* const rptr = stream_.next_in;
auto ret = inflate(&stream_, in_eof_ ? Z_FINISH : Z_NO_FLUSH);
auto got = max - stream_.avail_out;
if (ret == Z_STREAM_END) {
inflateEnd(&stream_);
initialized_ = false;
buffer_->consume(stream_.next_in - rptr);
} else if (ret == Z_OK) {
if (!in_eof_)
buffer_->consume(stream_.next_in - rptr);
} else {
return std::unexpected(
ret == Z_DATA_ERROR
? io::ReadError::InvalidData : io::ReadError::Error);
}
return got;
}
std::expected<size_t, io::ReadError> skip(size_t max) override {
auto tmp = std::make_unique_for_overwrite<char[]>(max);
return read(tmp.get(), max);
}
private:
std::optional<io::ReadError> fill() {
size_t avail;
auto* rptr = buffer_->rptr(avail);
if (!in_eof_ && avail < kBufferSizeZ / 2) {
auto* wptr = buffer_->wptr(avail);
auto got = reader_->read(wptr, avail);
if (got.has_value()) {
buffer_->commit(got.value());
if (got.value() == 0)
in_eof_ = true;
} else {
return got.error();
}
rptr = buffer_->rptr(avail);
}
// NOLINTNEXTLINE(misc-include-cleaner)
stream_.next_in = reinterpret_cast<z_const Bytef*>(rptr);
stream_.avail_in = std::min(
// NOLINTNEXTLINE(misc-include-cleaner)
static_cast<size_t>(std::numeric_limits<uInt>::max()), avail);
return std::nullopt;
}
std::unique_ptr<io::Reader> reader_;
bool const gzip_;
bool in_eof_{false};
std::unique_ptr<Buffer> buffer_{Buffer::fixed(kBufferSizeZ)};
bool initialized_{false};
z_stream stream_;
};
} // namespace
std::unique_ptr<io::Reader> zlib(std::unique_ptr<io::Reader> reader) {
return std::make_unique<DecompressReader>(std::move(reader), /* gzip = */ false);
}
std::unique_ptr<io::Reader> gzip(std::unique_ptr<io::Reader> reader) {
return std::make_unique<DecompressReader>(std::move(reader), /* gzip = */ true);
}
} // namespace decompress
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