[all-commits] [llvm/llvm-project] 2392ff: [libFuzzer] Error and exit if user supplied fuzzer...

[Matt Morehouse via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 2392ff093af128d5e46ce31e2ffa0b3e17185e32
      https://github.com/llvm/llvm-project/commit/2392ff093af128d5e46ce31e2ffa0b3e17185e32
  Author: Matt Morehouse <mascasa at google.com>
  Date:   2020-08-26 (Wed, 26 Aug 2020)

  Changed paths:
    M compiler-rt/lib/fuzzer/FuzzerDriver.cpp
    M compiler-rt/lib/fuzzer/FuzzerIO.h
    M compiler-rt/lib/fuzzer/FuzzerIOPosix.cpp
    M compiler-rt/lib/fuzzer/FuzzerIOWindows.cpp
    M compiler-rt/test/fuzzer/fuzzer-dirs.test

  Log Message:
  -----------
  [libFuzzer] Error and exit if user supplied fuzzer writeable directories don't exist

Currently, libFuzzer will exit with an error message if a non-existent
corpus directory is provided. However, if a user provides a non-existent
directory for the `artifact_prefix`, `exact_artifact_path`, or
`features_dir`, libFuzzer will continue execution but silently fail to
write artifacts/features.

To improve the user experience, this PR adds validation for the existence of
all user supplied directories before executing the main fuzzing loop. If they
don't exist, libFuzzer will exit with an error message.

Patch By: dgg5503

Reviewed By: morehouse

Differential Revision: https://reviews.llvm.org/D84808