How to add fuzzers (partially cribbed from oss-fuzz[0]):

1. git clone https://github.com/google/oss-fuzz
2. cd oss-fuzz
3. python infra/helper.py build_image mercurial

4. docker run --cap-add=SYS_PTRACE -it -v $HG_REPO_PATH:/hg-new

   gcr.io/oss-fuzz/mercurial bash

5. cd /src
6. rm -r mercurial
7. ln -s /hg-new mercurial
8. cd mercurial
9. compile
10. ls $OUT

Step 9 is literally running the command "compile", which is part of the docker container. Once you have that working, you can build the fuzzers like this (in the oss-fuzz repo):

python infra/helper.py build_fuzzers --sanitizer address mercurial $HG_REPO_PATH

(you can also say "memory", "undefined" or "coverage" for sanitizer). Then run the built fuzzers like this:

python infra/helper.py run_fuzzer mercurial -- $FUZZER

0: https://github.com/google/oss-fuzz/blob/master/docs/new_project_guide.md