From 8c6eb1566c28aadbcf43208ab984e8c50b7e1c6f Mon Sep 17 00:00:00 2001
From: Etienne Bergeron <etienneb@google.com>
Date: Wed, 27 Jul 2016 16:16:54 +0000
Subject: [PATCH] [compiler-rt] Fix warnings in interception code

Summary:
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__

Reviewers: rnk

Subscribers: kcc, hans, kubabrecka, llvm-commits, bruno, chrisha

Differential Revision: https://reviews.llvm.org/D22758

llvm-svn: 276885
---
 compiler-rt/lib/asan/asan_interceptors.cc                   | 6 ++++--
 compiler-rt/lib/asan/tests/asan_str_test.cc                 | 2 ++
 compiler-rt/lib/interception/interception.h                 | 2 ++
 .../lib/sanitizer_common/sanitizer_common_interceptors.inc  | 4 ++++
 4 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/compiler-rt/lib/asan/asan_interceptors.cc b/compiler-rt/lib/asan/asan_interceptors.cc
index 518ceebf62a5..a368b6a89620 100644
--- a/compiler-rt/lib/asan/asan_interceptors.cc
+++ b/compiler-rt/lib/asan/asan_interceptors.cc
@@ -725,11 +725,13 @@ void InitializeAsanInterceptors() {
   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));
 
diff --git a/compiler-rt/lib/asan/tests/asan_str_test.cc b/compiler-rt/lib/asan/tests/asan_str_test.cc
index dd755875e740..0b86702c4ae3 100644
--- a/compiler-rt/lib/asan/tests/asan_str_test.cc
+++ b/compiler-rt/lib/asan/tests/asan_str_test.cc
@@ -457,11 +457,13 @@ TEST(AddressSanitizer, StrArgsOverlapTest) {
 #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.
diff --git a/compiler-rt/lib/interception/interception.h b/compiler-rt/lib/interception/interception.h
index 9e9aca215c4d..f490c3961303 100644
--- a/compiler-rt/lib/interception/interception.h
+++ b/compiler-rt/lib/interception/interception.h
@@ -158,10 +158,12 @@ const interpose_substitution substitution_##func_name[] \
     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, ...) \
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
index 3660f6b8b343..f9ccca3e1069 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -663,12 +663,16 @@ INTERCEPTOR(void*, memchr, const void *s, int c, SIZE_T n) {
     return internal_memchr(s, c, n);
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, memchr, s, c, n);
+#if 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;