test(fuzz): changes to fuzz corpus seeding for better coverage - #5338
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lgritz wants to merge 1 commit into
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test(fuzz): changes to fuzz corpus seeding for better coverage#5338lgritz wants to merge 1 commit into
lgritz wants to merge 1 commit into
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The old rule copied only the 5 smallest files (<=100 KB) per format into the run corpus. Sorting by size and taking the first few systematically selected degenerate inputs (decompression bombs, truncated headers) and discarded the real, structurally rich images -- the worst bias for a coverage-guided mutation fuzzer, which needs valid deep-decode states to mutate around to find subtle bugs. - populate_corpora.py: drop the MAX_FILES count cap; gather every example from each format's FORMAT_SOURCES (testsuite fixtures + companion repos). Raise the per-file size cap from 100 KB to 5 MB (a throughput guard only; covers essentially all our test images). - ci-fuzztest.bash: gather seeds into a scratch seed_dir, then run `oiio_fuzz_image -merge=1` to fold only the coverage-increasing subset into the cached run corpus before the timed session. A crash during merge (a committed seed or testsuite fixture that itself trips the decoder) fails the job. - docs/dev/fuzzing.md: document the gather-all + merge model and the rule that regression fixtures live in testsuite/ (wired into FORMAT_SOURCES), not duplicated into src/fuzz/corpora/. Assisted-by: Claude Code / Claude Opus 4.8 Signed-off-by: Larry Gritz <lg@larrygritz.com>
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The old rule copied only the 5 smallest files (<=100 KB) per format into the run corpus. This is really biased and favors degenerate inputs (decompression bombs, truncated headers) over larger valid files as the basis to mutate around to find subtle bugs. So we make these changes:
oiio_fuzz_image -merge=1to fold only the coverage-increasing subset into the cached run corpus before the timed session.Assisted-by: Claude Code / Claude Opus 4.8