Handle NetBSD specific indirection of libpthread functions

[krytarowski]

Summary

Correct handling of three libpthread(3) functions on NetBSD:

• pthread_mutex_lock(3),
• pthread_mutex_unlock(3),
• pthread_setcancelstate(3).

Code out of the libpthread(3) context uses the libc symbols:

• __libc_mutex_lock,
• __libc_mutex_unlock,
• __libc_thr_setcancelstate.

The threading library (libpthread(3)) defines strong aliases:

• strong_alias(libc_mutex_lock,pthread_mutex_lock)
• strong_alias(libc_mutex_unlock,pthread_mutex_unlock)
• strong_alias(libc_thr_setcancelstate,pthread_setcancelstate)

This caused that these functions were invisible to sanitizers on NetBSD.
Intercept the libc-specific ones and add them as NetBSD-specific aliases
for the common pthread(3) ones.

NetBSD needs to intercept both functions, as the regularly named ones
are used internally in libpthread(3).

Sponsored by <The NetBSD Foundation>

lib/sanitizer_common/sanitizer_common_interceptors.inc

 #define INIT_PTHREAD_MUTEX_LOCK COMMON_INTERCEPT_FUNCTION(pthread_mutex_lock)
 #define INIT_PTHREAD_MUTEX_UNLOCK \
   COMMON_INTERCEPT_FUNCTION(pthread_mutex_unlock)
 #else
 #define INIT_PTHREAD_MUTEX_LOCK
 #define INIT_PTHREAD_MUTEX_UNLOCK
 #endif
 
+#if SANITIZER_NETBSD
+INTERCEPTOR(void, __libc_mutex_lock, void *m) \
+  ALIAS(WRAPPER_NAME(pthread_mutex_lock));
+INTERCEPTOR(void, __libc_mutex_unlock, void *m) \
+  ALIAS(WRAPPER_NAME(pthread_mutex_unlock));
+INTERCEPTOR(void, __libc_thr_setcancelstate, int state, int *oldstate) \
+  ALIAS(WRAPPER_NAME(pthread_setcancelstate));
+#endif
+
 #if SANITIZER_INTERCEPT_GETMNTENT || SANITIZER_INTERCEPT_GETMNTENT_R
 static void write_mntent(void *ctx, __sanitizer_mntent *mnt) {
   COMMON_INTERCEPTOR_WRITE_RANGE(ctx, mnt, sizeof(*mnt));
   if (mnt->mnt_fsname)
     COMMON_INTERCEPTOR_WRITE_RANGE(ctx, mnt->mnt_fsname,
                                    REAL(strlen)(mnt->mnt_fsname) + 1);
   if (mnt->mnt_dir)
     COMMON_INTERCEPTOR_WRITE_RANGE(ctx, mnt->mnt_dir,

   INIT___LXSTAT;
   INIT___LXSTAT64;
   // FIXME: add other *stat interceptors.
   INIT_UTMP;
   INIT_UTMPX;
   INIT_GETLOADAVG;
   INIT_WCSLEN;
   INIT_WCSCAT;
+
+#if SANITIZER_NETBSD
+  COMMON_INTERCEPT_FUNCTION(__libc_mutex_lock);
+  COMMON_INTERCEPT_FUNCTION(__libc_mutex_unlock);
+  COMMON_INTERCEPT_FUNCTION(__libc_thr_setcancelstate);
+#endif
 }