Fuzzing for LLVM-libc functions

Fuzz tests are used to ensure quality and security of LLVM-libc implementations. All fuzz tests live under the directory named fuzzing. Within this directory, the fuzz test for a libc function lives in the same nested directory as its implementation in the toplevel src directory. The build target libc-fuzzer builds all of the enabled fuzz tests (but does not run them).

Types of fuzz tests

As of this writing, there are two different kinds of fuzz tests. One kind are the traditional fuzz tests which test one function at a time and only that particular function. The other kind of tests are what we call as the differential fuzz tests. These tests compare the behavior of LLVM libc implementations with the behavior of the corresponding functions from the system libc.