1 files changed, 34 insertions, 0 deletions
diff --git a/lib/tsan/lit_tests/user_fopen.cc b/lib/tsan/lit_tests/user_fopen.cc
new file mode 100644
index 0000000000000..794d598719b4f
--- /dev/null
+++ b/lib/tsan/lit_tests/user_fopen.cc
@@ -0,0 +1,34 @@
+// RUN: %clangxx_tsan -O1 %s -o %t && %t 2>&1 | FileCheck %s
+#include <stdio.h>
+#include <stdlib.h>
+
+// defined by tsan.
+extern "C" FILE *__interceptor_fopen(const char *file, const char *mode);
+extern "C" int __interceptor_fileno(FILE *f);
+
+extern "C" FILE *fopen(const char *file, const char *mode) {
+  static int first = 0;
+  if (__sync_lock_test_and_set(&first, 1) == 0)
+    printf("user fopen\n");
+  return __interceptor_fopen(file, mode);
+}
+
+extern "C" int fileno(FILE *f) {
+  static int first = 0;
+  if (__sync_lock_test_and_set(&first, 1) == 0)
+    printf("user fileno\n");
+  return 1;
+}
+
+int main() {
+  FILE *f = fopen("/dev/zero", "r");
+  if (f) {
+    char buf;
+    fread(&buf, 1, 1, f);
+    fclose(f);
+  }
+}
+
+// CHECK: user fopen
+// CHECK-NOT: ThreadSanitizer
+