fa13e1b0c5 build: Add option --enable-danger-fuzz-link-all (MarcoFalke)
44444ba759 fuzz: Link all targets once (MarcoFalke)
Pull request description:
Currently the linker is invoked more than 150 times when compiling with `--enable-fuzz`. This is problematic for several reasons:
* It wastes disk space north of 20 GB, as all libraries and sanitizers are linked more than 150 times
* It wastes CPU time, as the link step can practically not be cached (similar to ccache for object files)
* It makes it a blocker to compile the fuzz tests by default for non-fuzz builds #19388, for the aforementioned reasons
* The build file is several thousand lines of code, without doing anything meaningful except listing each fuzz target in a highly verbose manner
* It makes writing new fuzz tests unnecessarily hard, as build system knowledge is required; Compare that to boost unit tests, which can be added by simply editing an existing cpp file
* It encourages fuzz tests that re-use the `buffer` or assume the `buffer` to be concatenations of seeds, which increases complexity of seeds and complexity for the fuzz engine to explore; Thus reducing the effectiveness of the affected fuzz targets
Fixes#20088
ACKs for top commit:
practicalswift:
Tested ACK fa13e1b0c5
sipa:
ACK fa13e1b0c5. Reviewed the code changes, and tested the 3 different test_runner.py modes (run once, merge, generate). I also tested building with the new --enable-danger-fuzz-link-all
Tree-SHA512: 962ab33269ebd51810924c51266ecc62edd6ddf2fcd9a8c359ed906766f58c3f73c223f8d3cc49f2c60f0053f65e8bdd86ce9c19e673f8c2b3cd676e913f2642
8c09c0c1d1 fuzz: Avoid time-based "non-determinism" in fuzzing harnesses by using mocked GetTime() (practicalswift)
Pull request description:
Avoid time-based "non-determinism" in fuzzing harnesses by using mocked `GetTime()`.
Prior to this commit the fuzzing harnesses `banman`, `connman`, `net` and `rbf` had time-based "non-determinism". `addrman` is fixed in #20425. `process_message` and `process_messages` are left to fix: simply using mock time is not enough for them due to interaction with `IsInitialBlockDownload()`.
See [`doc/fuzzing.md`](https://github.com/bitcoin/bitcoin/blob/master/doc/fuzzing.md) for information on how to fuzz Bitcoin Core. Don't forget to contribute any coverage increasing inputs you find to the [Bitcoin Core fuzzing corpus repo](https://github.com/bitcoin-core/qa-assets).
Happy fuzzing :)
ACKs for top commit:
MarcoFalke:
review ACK 8c09c0c1d1
practicalswift:
> review ACK [8c09c0c](8c09c0c1d1)
Tree-SHA512: 32dfbead3dfd18cf4ff56dc2ea341aa977441b4e19a54879cf54fa5820c7e2b14b92c7e238d32fd785654f3b28cc82826ae66c03e94c292633c63c41196ba9a8
