wip: Split fuzz binary (take 2) #30882

1. 
   dergoegge commented at 3:16 pm on September 12, 2024: member

   Closes #28971

   In addition to the benefits listed in #28971, this should also enable us to use https://github.com/ossf/fuzz-introspector provided by oss-fuzz. Our current runtime harness selection blocks introspector’s static analysis from working properly (e.g. it can’t statically determine which functions are reachable by a given harness).

   This PR uses the approach suggested here: #29010 (comment). The list of available harnesses is determined (prior to compiling) by grepping for harness names in FUZZ_TARGET invocations. When compiling with -DBUILD_INDIVIDUAL_FUZZ_BINARIES=ON, individual binaries for each harness are produced that no longer include the runtime lookup via the FUZZ environment variable.

   0cmake -B build_fuzz \
   1  -DBUILD_FOR_FUZZING=ON \
   2  -DBUILD_INDIVIDUAL_FUZZ_BINARIES=ON \
   3  -DSANITIZERS=fuzzer
   4cmake --build build_fuzz
   

   build_fuzz/src/test/fuzz will contain the individual binaries, which are prefixed with fuzz_*.

   I’m opening this now to get some early feedback, there are still a few things to address:

   • mention -DBUILD_INDIVIDUAL_FUZZ_BINARIES in the docs
   • include wallet harnesses
   • CI job that builds individual binaries (perhaps verify that the list of produced harnesses matches the monolithic binary)
2. 
   DrahtBot commented at 3:16 pm on September 12, 2024: contributor

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   Conflicts

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   • #28676 ([WIP] Cluster mempool implementation by sdaftuar)

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3. in src/test/fuzz/util/CMakeLists.txt:7 in 66c288a4cd outdated

   20-
   21-if(NOT FUZZ_BINARY_LINKS_WITHOUT_MAIN_FUNCTION)
   22-  target_compile_definitions(test_fuzz PRIVATE PROVIDE_FUZZ_MAIN_FUNCTION)
   23+if(BUILD_INDIVIDUAL_FUZZ_BINARIES)
   24+  # bash command produces list of harnesses: <harness name> <source file>
   25+  execute_process(
   

   ---

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   dergoegge commented at 3:20 pm on September 12, 2024:

   Currently an individual test_fuzz_* lib and fuzz_* binary is produced for each harness. It’s kind of ugly to duplicate this loop but I’m not sure to avoid it. Another loop would likely need to be added for the wallet harnesses as well. @hebasto @fanquake @maflcko Any ideas?
4. 
   dergoegge commented at 3:21 pm on September 12, 2024: member

   Trying to produce an introspector report using this branch: https://github.com/dergoegge/oss-fuzz/tree/2024-09-bitcoin-introspector
5. [fuzz] Avoid FUZZ_TARGET invocation in namespace 7668a5d4ec
6. [test] Define G_TRANSLATION_FUN per test binary (fuzz, test_bitcoin) 12bce0d311
7. wip individual fuzz bins d527100ad3
8. dergoegge force-pushed on Sep 12, 2024
9. DrahtBot added the label CI failed on Sep 13, 2024
10. 
    DrahtBot commented at 5:07 am on September 13, 2024: contributor

    🚧 At least one of the CI tasks failed. Debug: https://github.com/bitcoin/bitcoin/runs/30061858064

    Make sure to run all tests locally, according to the documentation.

    The failure may happen due to a number of reasons, for example:

    • Possibly due to a silent merge conflict (the changes in this pull request being incompatible with the current code in the target branch). If so, make sure to rebase on the latest commit of the target branch.

    • A sanitizer issue, which can only be found by compiling with the sanitizer and running the affected test.

    • An intermittent issue.

    Leave a comment here, if you need help tracking down a confusing failure.

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