@jazzer.js/fuzzer

This module provides a native Node.js addon which loads libfuzzer into Node.js. Users can install it with npm install, which tries to download a prebuilt shared object from GitHub but falls back to compilation on the user's machine if there is no suitable binary.

Loading the addon initializes libFuzzer and the sanitizer runtime. Users can then start the fuzzer with the exported startFuzzing or startFuzzingAsync functions; see the test for an example. In sync mode (--sync), the fuzzer runs on the main thread and blocks the event loop. In the default async mode, libFuzzer runs on a separate native thread and communicates with the JS event loop via a thread-safe function.

Development

The project can be built with npm run build (which is incremental after the first build); a subsequent npm test makes sure that the addon loads cleanly. Binaries can be prebuilt with npm run prebuild and uploaded with npm run prebuild -- --upload. Please format the code with clang-format (or use the format functionality of clangd).

Internally, the build system uses several steps:

1. package.json defines the npm scripts.
2. Several of them use prebuild or prebuild-install; together, those two tools implement a binary cache via GitHub releases, so that users don't have to build the code themselves.
3. We run prebuild with the cmake-js backend, which makes it call cmake-js to build the code when necessary.
4. cmake-js is a wrapper around CMake; it expects CMake and the C++ toolchain to exist on the machine already.
5. In our CMake configuration, we set up compiler-rt as an external project; CMake fetches and builds it before compiling our own code against it.

To debug build issues, it's often useful to start with a plain cmake-js compile or cmake-js recompile, which just invokes CMake with a few extra arguments that help it find the Node.js headers and such.

When working on the addon's C++ code, you may want to use a language server like clangd for IDE features. CMake is configured to emit a compile_commands.json file, so the language server should work after the first npm install.