Bugs are inevitable. Suffering is optional.
jonathanmetzman Add option to force reproduction (#533)
* Force repro

* Add message advertising -f

* Make Abhishek's suggested changes.

* Increment version.
Latest commit b134a16 Aug 28, 2018


ClusterFuzz tools

CircleCI Coverage Status

The tools supports various tasks (e.g. reproduce a crash locally) needed by ClusterFuzz's users.

Currently, it supports reproducing a crash locally. In the future, it will support uploading a fuzzer, tailing fuzzer log, and uploading a testcase.


  • gsutil
  • blackbox and xdotool; these can be installed with apt-get.


ClusterFuzz tools is a single binary file built with Pex. Therefore, you can simply copy the binary and run it.

For Goobuntu:

  1. Run prodaccess.
  2. Run /google/data/ro/teams/clusterfuzz-tools/releases/clusterfuzz reproduce -h.
  3. Run the release candidate version /google/data/ro/teams/clusterfuzz-tools/releases/clusterfuzz-rc reproduce -h. The release candidate version normally has newer features and updates.

For others:

  1. Download the latest stable version.
  2. Run clusterfuzz-<version>.pex reproduce -h.


See <binary> reproduce --help. Run <binary> reproduce [testcase-id].

Here's the workflow (we think) might be appropriate when fixing a bug:

  1. Run <binary> reproduce [testcase-id].
  2. Make a new branch and make a code change.
  3. Run against the code change with <binary> reproduce [testcase-id] --current.
  4. If the crash doesn’t occur anymore, it means your code change fixes the crash.

Here are some other useful options:

  -h, --help            show this help message and exit
  -c, --current         Use the current tree; On the other hand, without
                        --current, the Chrome repository will be switched to
                        the commit specified in the testcase.
  -b {download,chromium,standalone}, --build {download,chromium,standalone}
                        Select which type of build to run the testcase
  --disable-goma        Disable GOMA when building binaries locally.
  -j GOMA_THREADS, --goma-threads GOMA_THREADS
                        Manually specify the number of concurrent jobs for a
                        ninja build.
  -l GOMA_LOAD, --goma-load GOMA_LOAD
                        Manually specify maximum load average for a ninja
  -i ITERATIONS, --iterations ITERATIONS
                        Specify the number of times to attempt reproduction.
  -dx, --disable-xvfb   Disable running testcases in a virtual frame buffer.
  --target-args TARGET_ARGS
                        Additional arguments for the target (e.g. chrome).
  --edit-mode           Edit args.gn before building and target arguments
                        before running.
  --skip-deps           Skip installing dependencies: gclient sync, gclient
                        runhooks, install-build-deps.sh, and etc.
  --enable-debug        Build Chrome with full debug symbols by injecting
                        `sanitizer_keep_symbols = true` and `is_debug = true`
                        to args.gn. Ready to debug with GDB.