mirror of
https://github.com/fmtlib/fmt.git
synced 2024-12-02 22:40:10 +00:00
44 lines
1.4 KiB
Markdown
44 lines
1.4 KiB
Markdown
# FMT Fuzzer
|
|
|
|
Fuzzing has revealed [several bugs](https://github.com/fmtlib/fmt/issues?&q=is%3Aissue+fuzz)
|
|
in fmt. It is a part of the continous fuzzing at
|
|
[oss-fuzz](https://github.com/google/oss-fuzz).
|
|
|
|
The source code is modified to make the fuzzing possible without locking up on
|
|
resource exhaustion:
|
|
```cpp
|
|
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
|
|
if(spec.precision>100000) {
|
|
throw std::runtime_error("fuzz mode - avoiding large precision");
|
|
}
|
|
#endif
|
|
```
|
|
This macro is the defacto standard for making fuzzing practically possible, see
|
|
[the libFuzzer documentation](https://llvm.org/docs/LibFuzzer.html#fuzzer-friendly-build-mode).
|
|
|
|
## Running the fuzzers locally
|
|
|
|
There is a [helper script](build.sh) to build the fuzzers, which has only been
|
|
tested on Debian and Ubuntu linux so far. There should be no problems fuzzing on
|
|
Windows (using clang>=8) or on Mac, but the script will probably not work out of
|
|
the box.
|
|
|
|
Something along
|
|
```sh
|
|
mkdir build
|
|
cd build
|
|
export CXX=clang++
|
|
export CXXFLAGS="-fsanitize=fuzzer-no-link -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION= -g"
|
|
cmake .. -DFMT_SAFE_DURATION_CAST=On -DFMT_FUZZ=On -DFMT_FUZZ_LINKMAIN=Off -DFMT_FUZZ_LDFLAGS="-fsanitize=fuzzer"
|
|
cmake --build .
|
|
```
|
|
should work to build the fuzzers for all platforms which clang supports.
|
|
|
|
Execute a fuzzer with for instance
|
|
```sh
|
|
cd build
|
|
export UBSAN_OPTIONS=halt_on_error=1
|
|
mkdir out_chrono
|
|
bin/fuzzer_chrono_duration out_chrono
|
|
```
|