[tsan] Allow memchr interceptor to be used before initialization on OS X

[kubamracek]

Summary

On OS X, memchr is called on a newly created thread even before __tsan_thread_start_func is invoked, which means that the ThreadState object for that thread will not yet be initialized. Let's add COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED into the interceptor to simply call the original memchr in these cases.

[dvyukov]

lib/sanitizer_common/sanitizer_common_interceptors.inc

445 ↗

(On Diff #39057)

This is fragile (even if works for you). REAL interceptors are also initializes, so if nothing is initialized REAL(memchr) == 0. Call internal_memchr instead, like other cases do.

[kubamracek]

Updating patch.

[dvyukov]

LGTM

compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc

 
 #define INIT_MEMCMP COMMON_INTERCEPT_FUNCTION(memcmp)
 #else
 #define INIT_MEMCMP
 #endif
 
 #if SANITIZER_INTERCEPT_MEMCHR
 INTERCEPTOR(void*, memchr, const void *s, int c, SIZE_T n) {
+  if (COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED)
+    return internal_memchr(s, c, n);
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, memchr, s, c, n);
   void *res = REAL(memchr)(s, c, n);
   uptr len = res ? (char *)res - (const char *)s + 1 : n;
   COMMON_INTERCEPTOR_READ_RANGE(ctx, s, len);
   return res;
 }