Add debug assertions to ensure we never write too much to parsed_pattern #568
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zherczeg
approved these changes
Nov 18, 2024
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| Returns: the number of uint32_t units for parsed_pattern | ||
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| static ptrdiff_t |
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This was intentional. There is some arithmetic in the PCRE2_ASSERT lines, and some of the expressions are negative, so it made sense to make all the expressions signed rather than unsigned. Otherwise there would be ugly casts.
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A follow-up to #561.
The bug was found by fuzzing - but it would have been a serious problem if we'd made a release with this bug in.
I have added deterministic assertions, so that we don't rely on fuzzing, in case we make the same (easy) mistake again in future.
It's a little bit cumbersome, since there are two cases when we do write out more items to
parsed_patternthan we consume from the input: ")" after(*atomic_script_run:...will write out two META_KETs when it consumes the ")", and secondly a quantifier after(*ACCEPT)can write out a META_NOCAPTURE/META_KET pair.The code here is rather inelegant, but it's the best I could manage.