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/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/IntegralMath.h>
#include <AK/MemoryStream.h>
#include <AK/Span.h>
#include <AK/TypeCasts.h>
#include <AK/Types.h>
#include <LibCompress/Deflate.h>
#include <LibCompress/Zlib.h>
namespace Compress {
constexpr static size_t Adler32Size = sizeof(u32);
Optional<ZlibDecompressor> ZlibDecompressor::try_create(ReadonlyBytes data)
{
if (data.size() < (sizeof(ZlibHeader) + Adler32Size))
return {};
ZlibHeader header { .as_u16 = data.at(0) << 8 | data.at(1) };
if (header.compression_method != ZlibCompressionMethod::Deflate || header.compression_info > 7)
return {}; // non-deflate compression
if (header.present_dictionary)
return {}; // we dont support pre-defined dictionaries
if (header.as_u16 % 31 != 0)
return {}; // error correction code doesn't match
ZlibDecompressor zlib { header, data };
zlib.m_data_bytes = data.slice(2, data.size() - sizeof(ZlibHeader) - Adler32Size);
return zlib;
}
ZlibDecompressor::ZlibDecompressor(ZlibHeader header, ReadonlyBytes data)
: m_header(header)
, m_input_data(data)
{
}
Optional<ByteBuffer> ZlibDecompressor::decompress()
{
auto buffer_or_error = DeflateDecompressor::decompress_all(m_data_bytes);
if (buffer_or_error.is_error())
return {};
return buffer_or_error.release_value();
}
Optional<ByteBuffer> ZlibDecompressor::decompress_all(ReadonlyBytes bytes)
{
auto zlib = try_create(bytes);
if (!zlib.has_value())
return {};
return zlib->decompress();
}
u32 ZlibDecompressor::checksum()
{
if (!m_checksum) {
auto bytes = m_input_data.slice_from_end(Adler32Size);
m_checksum = bytes.at(0) << 24 | bytes.at(1) << 16 | bytes.at(2) << 8 || bytes.at(3);
}
return m_checksum;
}
ErrorOr<NonnullOwnPtr<ZlibCompressor>> ZlibCompressor::construct(MaybeOwned<Stream> stream, ZlibCompressionLevel compression_level)
{
// Zlib only defines Deflate as a compression method.
auto compression_method = ZlibCompressionMethod::Deflate;
// FIXME: Find a way to compress with Deflate's "Best" compression level.
auto compressor_stream = TRY(DeflateCompressor::construct(MaybeOwned(*stream), static_cast<DeflateCompressor::CompressionLevel>(compression_level)));
auto zlib_compressor = TRY(adopt_nonnull_own_or_enomem(new (nothrow) ZlibCompressor(move(stream), move(compressor_stream))));
TRY(zlib_compressor->write_header(compression_method, compression_level));
return zlib_compressor;
}
ZlibCompressor::ZlibCompressor(MaybeOwned<Stream> stream, NonnullOwnPtr<Stream> compressor_stream)
: m_output_stream(move(stream))
, m_compressor(move(compressor_stream))
{
}
ZlibCompressor::~ZlibCompressor()
{
VERIFY(m_finished);
}
ErrorOr<void> ZlibCompressor::write_header(ZlibCompressionMethod compression_method, ZlibCompressionLevel compression_level)
{
u8 compression_info = 0;
if (compression_method == ZlibCompressionMethod::Deflate) {
compression_info = AK::log2(DeflateCompressor::window_size) - 8;
VERIFY(compression_info <= 7);
}
ZlibHeader header {
.compression_method = compression_method,
.compression_info = compression_info,
.check_bits = 0,
.present_dictionary = false,
.compression_level = compression_level,
};
header.check_bits = 0b11111 - header.as_u16 % 31;
// FIXME: Support pre-defined dictionaries.
TRY(m_output_stream->write(header.as_u16.bytes()));
return {};
}
ErrorOr<Bytes> ZlibCompressor::read(Bytes)
{
return Error::from_errno(EBADF);
}
ErrorOr<size_t> ZlibCompressor::write(ReadonlyBytes bytes)
{
VERIFY(!m_finished);
size_t n_written = TRY(m_compressor->write(bytes));
m_adler32_checksum.update(bytes.trim(n_written));
return n_written;
}
bool ZlibCompressor::is_eof() const
{
return false;
}
bool ZlibCompressor::is_open() const
{
return m_output_stream->is_open();
}
void ZlibCompressor::close()
{
}
ErrorOr<void> ZlibCompressor::finish()
{
VERIFY(!m_finished);
if (is<DeflateCompressor>(m_compressor.ptr()))
TRY(static_cast<DeflateCompressor*>(m_compressor.ptr())->final_flush());
NetworkOrdered<u32> adler_sum = m_adler32_checksum.digest();
TRY(m_output_stream->write(adler_sum.bytes()));
m_finished = true;
return {};
}
ErrorOr<ByteBuffer> ZlibCompressor::compress_all(ReadonlyBytes bytes, ZlibCompressionLevel compression_level)
{
auto output_stream = TRY(try_make<AllocatingMemoryStream>());
auto zlib_stream = TRY(ZlibCompressor::construct(MaybeOwned<Stream>(*output_stream), compression_level));
TRY(zlib_stream->write_entire_buffer(bytes));
TRY(zlib_stream->finish());
auto buffer = TRY(ByteBuffer::create_uninitialized(output_stream->used_buffer_size()));
TRY(output_stream->read_entire_buffer(buffer.bytes()));
return buffer;
}
}
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