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It seems better not to compress signature dictionaries. Various PDF digital signing tools, including Adobe Acrobat Reader DC, do not compress signature dictionaries. Table 8.93 "Entries in a signature dictionary" in PDF 1.5 reference describes that /ByteRange in the signature dictionary shall be used to describe a digest that does not include the signature value (/Contents) itself. The byte ranges cannot be determined if the dictionary is compressed.
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Table 8.93 "Entries in a signature dictionary" in PDF 1.5 reference describes that the value of Contents entry is a hexadecimal string representation when ByteRange is specified. This commit makes QPDF always uses hexadecimal strings representation instead of literal strings for it.
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Ordinarily the trailer doesn't contain any strings, so this is usually a non-issue, but if the trailer contains strings, linearizing and encrypting with object streams would include encrypted strings in the trailer, which would blow out the padding because encrypted strings are longer than their cleartext counterparts.
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It's detected in QPDFWriter instead of at parse time because I can't figure out how to construct a test case in a reasonable time. This commit moves the fuzz file into the regular test suite for a QTC coverage case.
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Use destructors to pop the pipeline stack, and ensure that code that pops the stack is actually popping the intended thing.
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When seeing to a position based on a value read from the input, we are prone to integer overflow (fuzz issue 15442). Seek in two stages to move the overflow check into the input source code.
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Just because we know an indirect reference is null, doesn't mean we shouldn't keep it indirect.
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For some reason, qpdf from the beginning was replacing indirect references to null with literal null in arrays even after removing the old behavior of flattening scalar references. This seems like a bad idea.
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This message used to only appear for PDF >= 1.2. The invalid name is valid for PDF 1.0 and 1.1. However, since QPDFWriter may write a newer version, it's better to detect and warn in all cases. Therefore make the warning more informative.