| # The `libfuzzer-sys` Crate |
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| Barebones wrapper around LLVM's libFuzzer runtime library. |
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| The CPP parts are extracted from compiler-rt git repository with `git filter-branch`. |
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| libFuzzer relies on LLVM sanitizer support. The Rust compiler has built-in support for LLVM sanitizer support, for now, it's limited to Linux. As a result, `libfuzzer-sys` only works on Linux. |
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| ## Usage |
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| ### Use `cargo fuzz`! |
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| [The recommended way to use this crate with `cargo fuzz`!][cargo-fuzz]. |
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| [cargo-fuzz]: https://github.com/rust-fuzz/cargo-fuzz |
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| ### Manual Usage |
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| This crate can also be used manually as following: |
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| First create a new cargo project: |
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| ``` |
| $ cargo new --bin fuzzed |
| $ cd fuzzed |
| ``` |
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| Then add a dependency on the `fuzzer-sys` crate and your own crate: |
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| ```toml |
| [dependencies] |
| libfuzzer-sys = "0.4.0" |
| your_crate = { path = "../path/to/your/crate" } |
| ``` |
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| Change the `fuzzed/src/main.rs` to fuzz your code: |
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| ```rust |
| #![no_main] |
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| use libfuzzer_sys::fuzz_target; |
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| fuzz_target!(|data: &[u8]| { |
| // code to fuzz goes here |
| }); |
| ``` |
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| Build by running the following command: |
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| ```sh |
| $ cargo rustc -- \ |
| -C passes='sancov' \ |
| -C llvm-args='-sanitizer-coverage-level=3' \ |
| -C llvm-args='-sanitizer-coverage-inline-8bit-counters' \ |
| -Z sanitizer=address |
| ``` |
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| And finally, run the fuzzer: |
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| ```sh |
| $ ./target/debug/fuzzed |
| ``` |
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| ## Updating libfuzzer from upstream |
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| ``` |
| ./update-libfuzzer.sh <github.com/llvm-mirror/llvm-project SHA1> |
| ``` |
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| ## License |
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| All files in `libfuzzer` directory are licensed NCSA. |
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| Everything else is dual-licensed Apache 2.0 and MIT. |
