Integrating a Swift project

The process of integrating a project written in Swift with OSS-Fuzz is very similar to the general Setting up a new project process. The key specifics of integrating a Swift project are outlined below.

Project files

First, you need to write a Swift fuzz target that accepts a stream of bytes and calls the program API with that. This fuzz target should reside in your project repository.

The structure of the project directory in OSS-Fuzz repository doesn’t differ for projects written in Swift. The project files have the following Swift specific aspects.


The language attribute must be specified.

language: swift

The only supported fuzzing engine is libfuzzer

The supported sanitizers are and address, thread


  - libfuzzer
  - address
  - thread


The Dockerfile should start by FROM instead of using the simple base-builder

A precompile_swift generates an environment variable SWIFTFLAGS This can then be used in the building command such as swift build -c release $SWIFTFLAGS

A usage example from swift-protobuf project is

. precompile_swift
# build project
cd FuzzTesting
swift build -c debug $SWIFTFLAGS

cd .build/debug/
find . -maxdepth 1 -type f -name "*Fuzzer" -executable | while read i; do cp $i $OUT/"$i"-debug; done