66 lines
1.5 KiB
C++
66 lines
1.5 KiB
C++
/*
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* Copyright (c) 2020, the SerenityOS developers.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Span.h>
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#include <AK/Types.h>
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#include <LibCompress/Deflate.h>
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#include <LibCompress/Zlib.h>
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namespace Compress {
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constexpr static size_t Adler32Size = sizeof(u32);
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Optional<Zlib> Zlib::try_create(ReadonlyBytes data)
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{
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if (data.size() < (sizeof(ZlibHeader) + Adler32Size))
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return {};
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ZlibHeader header { .as_u16 = data.at(0) << 8 | data.at(1) };
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if (header.compression_method != ZlibCompressionMethod::Deflate || header.compression_info > 7)
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return {}; // non-deflate compression
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if (header.present_dictionary)
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return {}; // we dont support pre-defined dictionaries
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if (header.as_u16 % 31 != 0)
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return {}; // error correction code doesn't match
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Zlib zlib { header, data };
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zlib.m_data_bytes = data.slice(2, data.size() - sizeof(ZlibHeader) - Adler32Size);
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return zlib;
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}
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Zlib::Zlib(ZlibHeader header, ReadonlyBytes data)
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: m_header(header)
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, m_input_data(data)
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{
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}
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Optional<ByteBuffer> Zlib::decompress()
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{
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return DeflateDecompressor::decompress_all(m_data_bytes);
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}
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Optional<ByteBuffer> Zlib::decompress_all(ReadonlyBytes bytes)
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{
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auto zlib = try_create(bytes);
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if (!zlib.has_value())
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return {};
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return zlib->decompress();
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}
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u32 Zlib::checksum()
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{
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if (!m_checksum) {
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auto bytes = m_input_data.slice_from_end(Adler32Size);
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m_checksum = bytes.at(0) << 24 | bytes.at(1) << 16 | bytes.at(2) << 8 || bytes.at(3);
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}
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return m_checksum;
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}
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}
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