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/*
* Copyright (c) 2020, the SerenityOS developers
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/Assertions.h>
#include <AK/Span.h>
#include <AK/Types.h>
#include <AK/Vector.h>
#include <LibCompress/Deflate.h>
#include <LibCompress/Zlib.h>
namespace Compress {
Zlib::Zlib(ReadonlyBytes data)
{
m_input_data = data;
u8 compression_info = data.at(0);
u8 flags = data.at(1);
m_compression_method = compression_info & 0xF;
m_compression_info = (compression_info >> 4) & 0xF;
m_check_bits = flags & 0xF;
m_has_dictionary = (flags >> 5) & 0x1;
m_compression_level = (flags >> 6) & 0x3;
m_checksum = 0;
ASSERT(m_compression_method == 8);
ASSERT(m_compression_info == 7);
ASSERT(!m_has_dictionary);
ASSERT((compression_info * 256 + flags) % 31 == 0);
m_data_bytes = data.slice(2, data.size() - 2 - 4);
}
Optional<ByteBuffer> Zlib::decompress()
{
return DeflateDecompressor::decompress_all(m_data_bytes);
}
Optional<ByteBuffer> Zlib::decompress_all(ReadonlyBytes bytes)
{
Zlib zlib { bytes };
return zlib.decompress();
}
u32 Zlib::checksum()
{
if (!m_checksum) {
auto bytes = m_input_data.slice(m_input_data.size() - 4, 4);
m_checksum = bytes.at(0) << 24 | bytes.at(1) << 16 | bytes.at(2) << 8 || bytes.at(3);
}
return m_checksum;
}
}
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