More configurability

[Manishearth]

Add the ability to choose between debug/release. Pass down any other useful rustc flags.

[ruuda]

Being able to pass arguments to libfuzzer, such as -max_size= or the location of the corpus, would also be useful. Currently I run cargo fuzz --fuzz-target fuzzer_script_1 to trigger the build, kill it, and then I start fuzz/target/debug/fuzzer_script_1 with the desired flags.

Simply passing on any extra arguments to the target program would be sufficient.

[Manishearth]

Yep. cargo fuzz --fuzz-target foo -- FUZZ ARGS BLAH BLAH is what we'd probably use.

[nagisa]

You can pass args to the underlying binary now

(try cargo fuzz run target -- -help=1)

It is still desirable to have more configuration for how the fuzz target is compiled (release/debug, debug-assertions on or off, etc)

[Bobo1239]

Just asking for confirmation: Ignoring a function/crate (like https://clang.llvm.org/docs/SanitizerSpecialCaseList.html) would need rustc support, right?
(In my case rayon is triggering ASan though I believe that is rust-lang/rust#39882.)

[nagisa]

No, not really. It likely can be expressed through -C llvm-args in RUSTFLAGS.

[Bobo1239]

I did try RUSTFLAGS="-C llvm-args=-fsanitize-blacklist=blacklist.txt" cargo fuzz run fuzzer_script_1 but that only results in

error: failed to run `rustc` to learn about target-specific information
Caused by:
  process didn't exit successfully: `rustc - --crate-name ___ --print=file-names -C llvm-args=-fsanitize-blacklist=blacklist.txt -Cpasses=sancov -Cllvm-args=-sanitizer-coverage-level=3 -Zsanitizer=address -Cpanic=abort --crate-type bin --crate-type dylib --crate-type proc-macro --crate-type rlib --target x86_64-unknown-linux-gnu` (exit code: 1)
--- stderr
rustc: Unknown command line argument '-fsanitize-blacklist=blacklist.txt'.  Try: 'rustc -help'
rustc: Did you mean '-dfsan-abilist=blacklist.txt'?

Research led me to this commit hence my assumption.

edit: Just realized you may have meant expressing the the same thing but not actually using the same command line argument. In that case ignore the first part.

[Manishearth]

Fixed in #75 and #77