[sanitizer] Intercept sem_open/sem_unlink

Without interceptor implementation may call strlen on internal
buffers causing false msan errors.

Differential Revision: https://reviews.llvm.org/D107615

Author: vitalybuka

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

@@ -6538,14 +6538,39 @@ INTERCEPTOR(int, sem_getvalue, __sanitizer_sem_t *s, int *sval) {
   }
   return res;
 }
+
+INTERCEPTOR(__sanitizer_sem_t *, sem_open, const char *name, int oflag, ...) {
+  void *ctx;
+  va_list ap;
+  va_start(ap, oflag);
+  u32 mode = va_arg(ap, u32);
+  u32 value = va_arg(ap, u32);
+  COMMON_INTERCEPTOR_ENTER(ctx, sem_open, name, oflag, mode, value);
+  COMMON_INTERCEPTOR_READ_RANGE(ctx, name, REAL(strlen)(name) + 1);
+  __sanitizer_sem_t *s = REAL(sem_open)(name, oflag, mode, value);
+  if (s)
+    COMMON_INTERCEPTOR_INITIALIZE_RANGE(s, sizeof(*s));
+  va_end(ap);
+  return s;
+}
+
+INTERCEPTOR(int, sem_unlink, const char *name) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, sem_unlink, name);
+  COMMON_INTERCEPTOR_READ_RANGE(ctx, name, REAL(strlen)(name) + 1);
+  return REAL(sem_unlink)(name);
+}
+
 #  define INIT_SEM                            \
     COMMON_INTERCEPT_FUNCTION(sem_init);      \
     COMMON_INTERCEPT_FUNCTION(sem_destroy);   \
     COMMON_INTERCEPT_FUNCTION(sem_wait);      \
     COMMON_INTERCEPT_FUNCTION(sem_trywait);   \
     COMMON_INTERCEPT_FUNCTION(sem_timedwait); \
     COMMON_INTERCEPT_FUNCTION(sem_post);      \
-    COMMON_INTERCEPT_FUNCTION(sem_getvalue);
+    COMMON_INTERCEPT_FUNCTION(sem_getvalue);  \
+    COMMON_INTERCEPT_FUNCTION(sem_open);      \
+    COMMON_INTERCEPT_FUNCTION(sem_unlink);
 #else
 #  define INIT_SEM
 #endif  // SANITIZER_INTERCEPT_SEM

compiler-rt/test/sanitizer_common/TestCases/Posix/sem_open.cpp

@@ -0,0 +1,26 @@
+// RUN: %clangxx -O0 %s -o %t && %run %t
+
+// Android does not implement this calls.
+// UNSUPPORTED: android
+
+#include <assert.h>
+#include <fcntl.h>
+#include <semaphore.h>
+#include <stdio.h>
+#include <unistd.h>
+
+int main() {
+  char name[1024];
+  sprintf(name, "/sem_open_test_%d", getpid());
+
+  sem_t *s1 = sem_open(name, O_CREAT, 0644, 123);
+  assert(s1 != SEM_FAILED);
+
+  sem_t *s2 = sem_open(name, O_CREAT, 0644, 123);
+  assert(s2 != SEM_FAILED);
+
+  assert(sem_close(s1) == 0);
+  assert(sem_close(s2) == 0);
+
+  assert(sem_unlink(name) == 0);
+}