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LibCompress: Fail gracefuly on missing huffman codes in DeflateDecompressor
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@ -120,7 +120,8 @@ u32 CanonicalCode::read_symbol(InputBitStream& stream) const
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for (;;) {
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code_bits = code_bits << 1 | stream.read_bits(1);
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VERIFY(code_bits < (1 << 16));
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if (code_bits >= (1 << 16))
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return UINT32_MAX; // the maximum symbol in deflate is 288, so we use UINT32_MAX (an impossible value) to indicate an error
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// FIXME: This is very inefficient and could greatly be improved by implementing this
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// algorithm: https://www.hanshq.net/zip.html#huffdec
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@ -149,6 +150,11 @@ bool DeflateDecompressor::CompressedBlock::try_read_more()
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const auto symbol = m_literal_codes.read_symbol(m_decompressor.m_input_stream);
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if (symbol == UINT32_MAX) {
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m_decompressor.set_fatal_error();
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return false;
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}
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if (symbol < 256) {
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m_decompressor.m_output_stream << static_cast<u8>(symbol);
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return true;
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@ -162,7 +168,12 @@ bool DeflateDecompressor::CompressedBlock::try_read_more()
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}
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const auto length = m_decompressor.decode_length(symbol);
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const auto distance = m_decompressor.decode_distance(m_distance_codes.value().read_symbol(m_decompressor.m_input_stream));
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const auto distance_symbol = m_distance_codes.value().read_symbol(m_decompressor.m_input_stream);
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if (distance_symbol == UINT32_MAX) {
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m_decompressor.set_fatal_error();
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return false;
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}
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const auto distance = m_decompressor.decode_distance(distance_symbol);
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for (size_t idx = 0; idx < length; ++idx) {
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u8 byte = 0;
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@ -433,6 +444,11 @@ void DeflateDecompressor::decode_codes(CanonicalCode& literal_code, Optional<Can
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while (code_lengths.size() < literal_code_count + distance_code_count) {
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auto symbol = code_length_code.read_symbol(m_input_stream);
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if (symbol == UINT32_MAX) {
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set_fatal_error();
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return;
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}
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if (symbol < DeflateSpecialCodeLengths::COPY) {
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code_lengths.append(static_cast<u8>(symbol));
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continue;
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