Rewrite decode.py to always pick a valid codec#19
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sethmlarson merged 4 commits intopython:mainfrom Apr 7, 2026
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Since we're using FuzzerInput[0] directly as an integer this means potentially we'd start missing codecs if there are more than 256 of them. How many codecs are there today, are we at risk of getting close to that number? If so: maybe we take two bytes for the index, add an assert in there than len(ALL_CODECS) < 0xFFFF and call that good?
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We currently have 120, IIRC the last codec added was the oem codec, and that would have been ~8 years ago. I also updated to use pkgutil to iterate over encodings instead, that should be more complete. |
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Thanks for the review! |
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I don't quite get the original idea behind the fuzzer, as I assume currently it is failing with a
LookupErroron an invalid codec most of the time, never reaching any actual decoding. Instead, I suggest we drop the dictionary and pick a known codec. The codec rejection path is quite simple, I don't really think it is worth spending time fuzzing it.