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d71f05ca07
This makes all integer type conversions that have potential data loss explicit with calls that do range checks and raise an exception. After this commit, qpdf builds with no warnings when -Wsign-conversion -Wconversion is used with gcc or clang or when -W3 -Wd4800 is used with MSVC. This significantly reduces the likelihood of potential crashes from bogus integer values. There are some parts of the code that take int when they should take size_t or an offset. Such places would make qpdf not support files with more than 2^31 of something that usually wouldn't be so large. In the event that such a file shows up and is valid, at least qpdf would raise an error in the right spot so the issue could be legitimately addressed rather than failing in some weird way because of a silent overflow condition.
44 lines
1023 B
C++
44 lines
1023 B
C++
#ifndef PL_LZWDECODER_HH
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#define PL_LZWDECODER_HH
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#include <qpdf/Pipeline.hh>
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#include <qpdf/Buffer.hh>
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#include <vector>
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class Pl_LZWDecoder: public Pipeline
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{
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public:
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QPDF_DLL
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Pl_LZWDecoder(char const* identifier, Pipeline* next,
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bool early_code_change);
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QPDF_DLL
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virtual ~Pl_LZWDecoder();
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QPDF_DLL
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virtual void write(unsigned char* buf, size_t len);
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QPDF_DLL
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virtual void finish();
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private:
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void sendNextCode();
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void handleCode(unsigned int code);
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unsigned char getFirstChar(unsigned int code);
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void addToTable(unsigned char next);
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// members used for converting bits to codes
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unsigned char buf[3];
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unsigned int code_size;
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unsigned int next;
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unsigned int byte_pos;
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unsigned int bit_pos; // left to right: 01234567
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unsigned int bits_available;
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// members used for handle LZW decompression
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bool code_change_delta;
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bool eod;
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std::vector<Buffer> table;
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unsigned int last_code;
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};
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#endif // PL_LZWDECODER_HH
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