[compiler-rt] Add internal wcslen to avoid crashing on windows 64-bits

Summary:
The function wcslen is incorrectly hooked on windows 64-bits.

The interception library is not able to hook without breaking the code.
The function is too small and the interception must be done with
trampoline-hooking which turned out to be incorrect on a small
loop (first few instructions have a backedge).

Reviewers: rnk

Subscribers: wang0109, chrisha, llvm-commits, kubabrecka

Differential Revision: https://reviews.llvm.org/D22363

llvm-svn: 275488

compiler-rt/lib/asan/asan_interceptors.cc

@@ -585,7 +585,12 @@ INTERCEPTOR(char*, __strdup, const char *s) {
 INTERCEPTOR(SIZE_T, wcslen, const wchar_t *s) {
   void *ctx;
   ASAN_INTERCEPTOR_ENTER(ctx, wcslen);
+#if SANITIZER_WINDOWS64
+  // The function is incorrectly hooked on windows 64-bit.
+  SIZE_T length = internal_wcslen(s);
+#else
   SIZE_T length = REAL(wcslen)(s);
+#endif
   if (!asan_init_is_running) {
     ENSURE_ASAN_INITED();
     ASAN_READ_RANGE(ctx, s, (length + 1) * sizeof(wchar_t));

compiler-rt/lib/sanitizer_common/sanitizer_libc.cc

@@ -234,6 +234,12 @@ char *internal_strstr(const char *haystack, const char *needle) {
   return nullptr;
 }
 
+uptr internal_wcslen(const wchar_t *s) {
+  uptr i = 0;
+  while (s[i]) i++;
+  return i;
+}
+
 s64 internal_simple_strtoll(const char *nptr, char **endptr, int base) {
   CHECK_EQ(base, 10);
   while (IsSpace(*nptr)) nptr++;

compiler-rt/lib/sanitizer_common/sanitizer_libc.h

@@ -51,6 +51,7 @@ char *internal_strncpy(char *dst, const char *src, uptr n);
 uptr internal_strnlen(const char *s, uptr maxlen);
 char *internal_strrchr(const char *s, int c);
 // This is O(N^2), but we are not using it in hot places.
+uptr internal_wcslen(const wchar_t *s);
 char *internal_strstr(const char *haystack, const char *needle);
 // Works only for base=10 and doesn't set errno.
 s64 internal_simple_strtoll(const char *nptr, char **endptr, int base);