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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.
37 lines
748 B
C++
37 lines
748 B
C++
// Read bits from a bit stream. See BitWriter for writing.
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#ifndef BITSTREAM_HH
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#define BITSTREAM_HH
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#include <qpdf/DLL.h>
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#include <stddef.h>
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class BitStream
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{
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public:
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QPDF_DLL
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BitStream(unsigned char const* p, size_t nbytes);
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QPDF_DLL
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void reset();
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QPDF_DLL
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unsigned long long getBits(size_t nbits);
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QPDF_DLL
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long long getBitsSigned(size_t nbits);
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// Only call getBitsInt when requesting a number of bits that will
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// definitely fit in an int.
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QPDF_DLL
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int getBitsInt(size_t nbits);
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QPDF_DLL
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void skipToNextByte();
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private:
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unsigned char const* start;
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size_t nbytes;
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unsigned char const* p;
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size_t bit_offset;
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size_t bits_available;
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};
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#endif // BITSTREAM_HH
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