[MSan] Add __msan_unpoison_string() to the public interface.

Using __msan_unpoison() on null-terminated strings is awkward because
strlen() can't be called on a poisoned string. This case warrants a special
interface function.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@204448 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 7 insertions, 0 deletions

diff --git a/lib/msan/msan_interceptors.cc b/lib/msan/msan_interceptors.cc
index 8f30d4d0e..992d73516 100644
--- a/lib/msan/msan_interceptors.cc
+++ b/lib/msan/msan_interceptors.cc
@@ -1372,6 +1372,11 @@ void *__msan_memmove(void *dest, const void *src, SIZE_T n) {
   return res;
 }
 
+void __msan_unpoison_string(const char* s) {
+  if (!MEM_IS_APP(s)) return;
+  __msan_unpoison(s, REAL(strlen)(s) + 1);
+}
+
 namespace __msan {
 
 void CopyOrigin(void *dst, const void *src, uptr size, StackTrace *stack) {
diff --git a/lib/msan/msan_interface_internal.h b/lib/msan/msan_interface_internal.h
index 685a8c69f..ebafe3c5f 100644
--- a/lib/msan/msan_interface_internal.h
+++ b/lib/msan/msan_interface_internal.h
@@ -40,6 +40,8 @@ void __msan_warning_noreturn();
 SANITIZER_INTERFACE_ATTRIBUTE
 void __msan_unpoison(const void *a, uptr size);
 SANITIZER_INTERFACE_ATTRIBUTE
+void __msan_unpoison_string(const char *s);
+SANITIZER_INTERFACE_ATTRIBUTE
 void __msan_clear_and_unpoison(void *a, uptr size);
 SANITIZER_INTERFACE_ATTRIBUTE
 void* __msan_memcpy(void *dst, const void *src, uptr size);