Fuzzing harnesses lacking a corpus: simplicity_tx
Please consider adding a fuzz corpus at https://github.com/bitcoin-core/qa-assets
Traceback (most recent call last):
  File "/build/source/test/fuzz/test_runner.py", line 308, in <module>
    main()
  File "/build/source/test/fuzz/test_runner.py", line 176, in main
    run_once(
  File "/build/source/test/fuzz/test_runner.py", line 258, in run_once
    os.makedirs(corpus_path, exist_ok=True)
  File "<frozen os>", line 225, in makedirs
PermissionError: [Errno 13] Permission denied: '/nix/store/gcm4s8l5kgakpi4i2369z7jw85xhzkrw-qa-assets/fuzz_seed_corpus/simplicity_tx'

Might need to add a .gitignore in a directory.

@roconnor-blockstream the simplicity_tx directory is only used when ElementsProject/elements#1384 is merged. I believe this PR should work on master (except that it'll crash) or on ElementsProject/elements#1391.

I can add a .gitignore ahead of time if you think it'd be worthwhile.

Or you can try using #6.

Oh I mistakenly thought this was the simplicity PR.

Do you actually want to merge this, or do you want to reduce it first?

I don't know if it is actually reduced or not, but the branch name you are merging from and the fact that it is a million files suggests it isn't reduced.

@roconnor-blockstream I would like it merged as-is.

The branch name is misleading -- I ran my reduction pass on the "unreduced" branch and then dumped the reduced set of files back into the "unreduced" worktree. And the number of files appears to be 263318 -- which is a large number, but divided by 181 fuzz targets, is about 1400 seeds per target. I don't think I can get it meaningfully lower.

cc @delta1 now that we have merged the corresponding commit in Elements I think we can merge this one.

I have (spurious?) UBSan errors in minisketch in the master elements branch:

minisketch/src/fields/../int_utils.h:179:69: runtime error: shift exponent 32 is too large for 32-bit type 'unsigned int'

ACK efed9bf

@apoelstra happy to merge but I don't have permissions

Weird. Ok, I'll merge this for now and fix the perms later.

FYI it will break the fuzztests in Elements. But I think this is fine -- the fixes are easy (need to add another ubsan suppression and need to tweak the witness_program fuzz target) -- and it's not like we've been running the fuzzer in CI anyway.

...and it's really annoying having an open PR with 250k+ files changed. Every git operation related to this is horribly slow so I'd like it to be buried in the history as quickly as possible.