How to print the coverage report while using libfuzzer with MSVC?

Question

While using libfuzzer with MSVC the coverage section is empty. Is there a way to print the coverage report with libfuzzer & MSVC?

Answer 1

To print a coverage report while using libFuzzer with MSVC, you can follow these steps:

Install Clang: Ensure you have the Clang compiler installed. You can do this via the Visual Studio Installer by selecting the “C++ Clang Compiler for Windows” and “MSBuild support for LLVM (clang-cl)” components.

Set Up Your Project:

• Add the following flags to your compiler and linker settings:

     -fsanitize=fuzzer -fsanitize=address -fprofile-instr-generate -fcoverage-mapping
  

  Run Your Fuzz Tests:

Set the environment variable LLVM_PROFILE_FILE to specify the output file for the raw coverage data:

 set LLVM_PROFILE_FILE=my_test.profraw

• Execute your fuzz tests as usual.

  Generate the Coverage Report:

  • Use llvm-profdata to merge the raw profile data:

        llvm-profdata merge -sparse my_test.profraw -o my_test.profdata
    

  • Use llvm-cov to generate the coverage report:

        llvm-cov show ./your_fuzz_target_binary -instr-profile=my_test.profdata -format=html > coverage_report.html