In Windows, when the sanitizer is implemented as a static library and is included in the main executable, we need an auxiliary static library dll_thunk that will be linked to the dlls that have instrumentation, so they can refer to the runtime in the main executable. Basically, it uses interception to get a pointer the function in the main executable and override its function with that pointer.
Before this diff, all of this implementation was included in asan. In this diff I split it into different sanitizers, so we can use other sanitizers regardless of whether we include asan or not.
All the sanitizers will include a file sanitizer_win_dll_thunk.cc that register functions to be intercepted in the binary section: DLLTH
When the dll including dll_thunk is initialized, it will execute __dll_thunk_init() implemented in: sanitizer_common/sanitizer_win_dll_thunk.cc, which will consider all the CB registered in the section DLLTH. So, all the functions registered will be intercepted, and redirected to the implementation in the main executable.
All the files "sanitizer_win_dll_thunk.cc" are independent, so we don't need to include a specific list of sanitizers.
To create a dll_thunk for sanitizers SanitizerA and SanitizerB, we only need to compile: sanitizera/sanitizera_win_dll_thunk.cc sanitizerb/sanitizerb_win_dll_thunk.cc and sanitizer_common/sanitizer_win_dll_thunk.cc.
So, now, we compile: asan_win_dll_thunk.cc ubsan_win_dll_thunk.cc, sanitizer_coverage_win_dll_thunk.cc and sanitizer_win_dll_thunk.cc , to generate asan_dll_thunk, because we include asan, ubsan and sanitizer coverage in the address sanitizer library.
But we could also compile: sanitizer_coverage_win_dll_thunk.cc and sanitizer_win_dll_thunk.cc , to generate a dll_thunk only for sanitizer_coverage.
In a new diff I will add code to intercept weak functions.