From 8c34243a13173f564e9761266c3460f5531ede7a Mon Sep 17 00:00:00 2001
From: Kostya Serebryany <kcc@google.com>
Date: Wed, 3 May 2017 18:38:34 +0000
Subject: [PATCH] [asan] print the 'unexpected format specifier in printf
 interceptor' warning just once (came up in
 https://github.com/google/oss-fuzz/pull/562). Not touching a similar scanf
 warning -- for some reason it does not fire for me.

llvm-svn: 302064
---
 .../sanitizer_common_interceptors_format.inc         | 12 ++++++++----
 .../Linux/unexpected_format_specifier_test.cc        | 12 ++++++++++++
 2 files changed, 20 insertions(+), 4 deletions(-)
 create mode 100644 compiler-rt/test/sanitizer_common/TestCases/Linux/unexpected_format_specifier_test.cc

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_format.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_format.inc
index 12563499c515..5ebe5a6ba0dd 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_format.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_format.inc
@@ -325,8 +325,8 @@ static void scanf_common(void *ctx, int n_inputs, bool allowGnuMalloc,
       continue;
     int size = scanf_get_value_size(&dir);
     if (size == FSS_INVALID) {
-      Report("WARNING: unexpected format specifier in scanf interceptor: "
-        "%.*s\n", dir.end - dir.begin, dir.begin);
+      Report("%s: WARNING: unexpected format specifier in scanf interceptor: ",
+             SanitizerToolName, "%.*s\n", dir.end - dir.begin, dir.begin);
       break;
     }
     void *argp = va_arg(aq, void *);
@@ -520,8 +520,12 @@ static void printf_common(void *ctx, const char *format, va_list aq) {
       continue;
     int size = printf_get_value_size(&dir);
     if (size == FSS_INVALID) {
-      Report("WARNING: unexpected format specifier in printf "
-             "interceptor: %.*s\n", dir.end - dir.begin, dir.begin);
+      static int ReportedOnce;
+      if (!ReportedOnce++)
+        Report(
+            "%s: WARNING: unexpected format specifier in printf "
+            "interceptor: %.*s (reported once per process)\n",
+            SanitizerToolName, dir.end - dir.begin, dir.begin);
       break;
     }
     if (dir.convSpecifier == 'n') {
diff --git a/compiler-rt/test/sanitizer_common/TestCases/Linux/unexpected_format_specifier_test.cc b/compiler-rt/test/sanitizer_common/TestCases/Linux/unexpected_format_specifier_test.cc
new file mode 100644
index 000000000000..f48cce8ea22b
--- /dev/null
+++ b/compiler-rt/test/sanitizer_common/TestCases/Linux/unexpected_format_specifier_test.cc
@@ -0,0 +1,12 @@
+// RUN: %clang -w -O0 %s -o %t && %run %t 2>&1 | FileCheck %s
+// UNSUPPORTED: lsan
+// UNSUPPORTED: msan
+#include <stdio.h>
+int main() {
+  int a;
+  printf("%Q\n", 1);
+  printf("%Q\n", 1);
+  printf("%Q\n", 1);
+}
+// CHECK: unexpected format specifier in printf interceptor: %Q (reported once per process)
+// CHECK-NOT: unexpected format specifier in printf interceptor