[PATCH] D22758: [compiler-rt] Fix warnings in interception code

[Etienne Bergeron via llvm-commits]

etienneb created this revision.
etienneb added a reviewer: rnk.
etienneb added subscribers: chrisha, bruno, llvm-commits.
Herald added a subscriber: kubabrecka.

This patch is re-introducing the code to fix the
dynamic hooking on windows and to fix a compiler
warning on Apple.

Related patches:

* https://reviews.llvm.org/D22641
* https://reviews.llvm.org/D22610
* https://reviews.llvm.org/rL276311
* https://reviews.llvm.org/rL276490

Both architecture are using different techniques to
hook on library functions (memchr, strcpy,...). 

On Apple, the function is not dynamically hooked and
the symbol always points to a valid function 
(i.e. can't be null). The REAL macro returns the
symbol.

On windows, the function is dynamically patch and the
REAL(...) function may or may not be null. It depend
on whether or not the function was hooked correctly.
Also, on windows memcpy and memmove are the same.

```
#if !defined(__APPLE__)
[...]
# define REAL(x) __interception::PTR_TO_REAL(x)
# define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src)
[...]
#else  // __APPLE__
[...]
# define REAL(x) x
# define ASSIGN_REAL(x, y)
[...]
#endif  // __APPLE__

https://reviews.llvm.org/D22758

Files:
  lib/asan/asan_interceptors.cc
  lib/asan/tests/asan_str_test.cc
  lib/interception/interception.h
  lib/sanitizer_common/sanitizer_common_interceptors.inc

Index: lib/sanitizer_common/sanitizer_common_interceptors.inc
===================================================================
--- lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -663,12 +663,16 @@
     return internal_memchr(s, c, n);
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, memchr, s, c, n);
+#ifdef SANITIZER_WINDOWS
   void *res;
   if (REAL(memchr)) {
     res = REAL(memchr)(s, c, n);
   } else {
     res = internal_memchr(s, c, n);
   }
+#else
+  void *res = REAL(memchr)(s, c, n);
+#endif
   uptr len = res ? (char *)res - (const char *)s + 1 : n;
   COMMON_INTERCEPTOR_READ_RANGE(ctx, s, len);
   return res;
Index: lib/interception/interception.h
===================================================================
--- lib/interception/interception.h
+++ lib/interception/interception.h
@@ -158,10 +158,12 @@
     namespace __interception { \
       extern FUNC_TYPE(func) PTR_TO_REAL(func); \
     }
+# define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src)
 #else  // __APPLE__
 # define REAL(x) x
 # define DECLARE_REAL(ret_type, func, ...) \
     extern "C" ret_type func(__VA_ARGS__);
+# define ASSIGN_REAL(x, y)
 #endif  // __APPLE__
 
 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
Index: lib/asan/tests/asan_str_test.cc
===================================================================
--- lib/asan/tests/asan_str_test.cc
+++ lib/asan/tests/asan_str_test.cc
@@ -457,12 +457,14 @@
 #if !defined(__APPLE__) || !defined(MAC_OS_X_VERSION_10_7) || \
     (MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7)
   // Check "memcpy". Use Ident() to avoid inlining.
+#if PLATFORM_HAS_DIFFERENT_MEMCPY_AND_MEMMOVE
   memset(str, 'z', size);
   Ident(memcpy)(str + 1, str + 11, 10);
   Ident(memcpy)(str, str, 0);
   EXPECT_DEATH(Ident(memcpy)(str, str + 14, 15), OverlapErrorMessage("memcpy"));
   EXPECT_DEATH(Ident(memcpy)(str + 14, str, 15), OverlapErrorMessage("memcpy"));
 #endif
+#endif
 
   // We do not treat memcpy with to==from as a bug.
   // See http://llvm.org/bugs/show_bug.cgi?id=11763.
Index: lib/asan/asan_interceptors.cc
===================================================================
--- lib/asan/asan_interceptors.cc
+++ lib/asan/asan_interceptors.cc
@@ -725,11 +725,13 @@
   InitializeCommonInterceptors();
 
   // Intercept mem* functions.
-  ASAN_INTERCEPT_FUNC(memcpy);
+  ASAN_INTERCEPT_FUNC(memmove);
   ASAN_INTERCEPT_FUNC(memset);
   if (PLATFORM_HAS_DIFFERENT_MEMCPY_AND_MEMMOVE) {
     // In asan, REAL(memmove) is not used, but it is used in msan.
-    ASAN_INTERCEPT_FUNC(memmove);
+    ASAN_INTERCEPT_FUNC(memcpy);
+  } else {
+    ASSIGN_REAL(memcpy, memmove);
   }
   CHECK(REAL(memcpy));
 


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