[Sanitizer] Add interceptor for wctomb

Summary:
This is required to avoid msan false positives for code using this
function (although generally one should avoid using this function in
favor of wcrtomb).

Reviewers: eugenis, EricWF, vitalybuka

Subscribers: srhines, kubamracek, fedor.sergeev, delcypher, llvm-commits, #sanitizers

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D59548

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@357240 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 23 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_common_interceptors.inc b/lib/sanitizer_common/sanitizer_common_interceptors.inc
index 4ea274f78..b3be48d75 100644
--- a/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -3540,6 +3540,28 @@ INTERCEPTOR(SIZE_T, wcrtomb, char *dest, wchar_t src, void *ps) {
 #define INIT_WCRTOMB
 #endif
 
+#if SANITIZER_INTERCEPT_WCTOMB
+INTERCEPTOR(int, wctomb, char *dest, wchar_t src) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, wctomb, dest, src);
+  if (!dest)
+    return REAL(wctomb)(dest, src);
+
+  char local_dest[32];
+  int res = REAL(wctomb)(local_dest, src);
+  if (res != -1) {
+    CHECK_LE(res, sizeof(local_dest));
+    COMMON_INTERCEPTOR_WRITE_RANGE(ctx, dest, res);
+    REAL(memcpy)(dest, local_dest, res);
+  }
+  return res;
+}
+
+#define INIT_WCTOMB COMMON_INTERCEPT_FUNCTION(wctomb);
+#else
+#define INIT_WCTOMB
+#endif
+
 #if SANITIZER_INTERCEPT_TCGETATTR
 INTERCEPTOR(int, tcgetattr, int fd, void *termios_p) {
   void *ctx;
@@ -9616,6 +9638,7 @@ static void InitializeCommonInterceptors() {
   INIT_WCSTOMBS;
   INIT_WCSNRTOMBS;
   INIT_WCRTOMB;
+  INIT_WCTOMB;
   INIT_TCGETATTR;
   INIT_REALPATH;
   INIT_CANONICALIZE_FILE_NAME;