[sanitizer] Move interceptor initialization check into real_clock_gettime

[vitalybuka]

@kubamracek Is this going to work for D53528 ?

[kubamracek]

I'll try the patch and get back to you. I'm not sure if COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED is the right thing to check here. Checking &REAL(clock_gettime) == nullptr would work.

[kubamracek]

Okay, yup, this works. Thanks!

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

INTERCEPTOR(int, clock_gettime, u32 clk_id, void *tp) {
   if (!res) {
     COMMON_INTERCEPTOR_WRITE_RANGE(ctx, tp, struct_timespec_sz);
   }
   return res;
 }
 namespace __sanitizer {
 extern "C" {
 int real_clock_gettime(u32 clk_id, void *tp) {
+  if (COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED)
+    return internal_clock_gettime(clk_id, tp);
   return REAL(clock_gettime)(clk_id, tp);
 }
 }  // extern "C"
 }  // namespace __sanitizer
 INTERCEPTOR(int, clock_settime, u32 clk_id, const void *tp) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, clock_settime, clk_id, tp);
   COMMON_INTERCEPTOR_READ_RANGE(ctx, tp, struct_timespec_sz);

compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cc

if (SANITIZER_ANDROID)
     return true;
   if (&__progname && __progname && *__progname)
     return true;
   return false;
 }
 
 // MonotonicNanoTime is a timing function that can leverage the vDSO by calling
 // clock_gettime. real_clock_gettime only exists if clock_gettime is
-// intercepted, so define it weakly and use it if available. MonotonicNanoTime
-// might also be called when interceptors are not yet initialized, so check for
-// that as well.
+// intercepted, so define it weakly and use it if available.
 extern "C" SANITIZER_WEAK_ATTRIBUTE
 int real_clock_gettime(u32 clk_id, void *tp);
-namespace __interception { int (*real_clock_gettime)(u32 clk_id, void *tp); }
 u64 MonotonicNanoTime() {
   timespec ts;
-  if (CanUseVDSO() && __interception::real_clock_gettime) {
+  if (CanUseVDSO()) {
     if (&real_clock_gettime)
       real_clock_gettime(CLOCK_MONOTONIC, &ts);
     else
       clock_gettime(CLOCK_MONOTONIC, &ts);
   } else {
     internal_clock_gettime(CLOCK_MONOTONIC, &ts);
   }
   return (u64)ts.tv_sec * (1000ULL * 1000 * 1000) + ts.tv_nsec;