From 711bea9dedd81cffa4d04dc6bb9edee933e04aaf Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel@labath.sk>
Date: Fri, 29 Mar 2019 08:39:03 +0000
Subject: [PATCH] [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

llvm-svn: 357240
---
 compiler-rt/lib/msan/tests/msan_test.cc            | 10 ++++++++++
 .../sanitizer_common_interceptors.inc              | 23 ++++++++++++++++++++++
 .../sanitizer_platform_interceptors.h              |  3 +++
 .../test/sanitizer_common/TestCases/wctomb.c       | 14 +++++++++++++
 4 files changed, 50 insertions(+)
 create mode 100644 compiler-rt/test/sanitizer_common/TestCases/wctomb.c

diff --git a/compiler-rt/lib/msan/tests/msan_test.cc b/compiler-rt/lib/msan/tests/msan_test.cc
index d2002d1..9d2f5a7 100644
--- a/compiler-rt/lib/msan/tests/msan_test.cc
+++ b/compiler-rt/lib/msan/tests/msan_test.cc
@@ -2123,6 +2123,16 @@ TEST(MemorySanitizer, wcrtomb) {
   EXPECT_EQ(buff[0], 'a');
 }
 
+TEST(MemorySanitizer, wctomb) {
+  wchar_t x = L'a';
+  char buff[10];
+  wctomb(nullptr, x);
+  int res = wctomb(buff, x);
+  EXPECT_EQ(res, 1);
+  EXPECT_EQ(buff[0], 'a');
+  EXPECT_POISONED(buff[1]);
+}
+
 TEST(MemorySanitizer, wmemset) {
     wchar_t x[25];
     break_optimization(x);
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
index 4ea274f..b3be48d 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/compiler-rt/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;
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h b/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
index a4116f8..3cbdd01 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
@@ -283,6 +283,9 @@
 #define SANITIZER_INTERCEPT_WCRTOMB                                           \
   (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
   SI_SOLARIS)
+#define SANITIZER_INTERCEPT_WCTOMB                                           \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
+  SI_SOLARIS)
 #define SANITIZER_INTERCEPT_TCGETATTR SI_LINUX_NOT_ANDROID || SI_SOLARIS
 #define SANITIZER_INTERCEPT_REALPATH SI_POSIX
 #define SANITIZER_INTERCEPT_CANONICALIZE_FILE_NAME \
diff --git a/compiler-rt/test/sanitizer_common/TestCases/wctomb.c b/compiler-rt/test/sanitizer_common/TestCases/wctomb.c
new file mode 100644
index 0000000..87089d2
--- /dev/null
+++ b/compiler-rt/test/sanitizer_common/TestCases/wctomb.c
@@ -0,0 +1,14 @@
+// RUN: %clang %s -o %t && %run %t 2>&1
+
+#include <assert.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv) {
+  char buff[10];
+  wchar_t x = L'a';
+  wctomb(NULL, x);
+  int res = wctomb(buff, x);
+  assert(res == 1);
+  assert(buff[0] == 'a');
+  return 0;
+}
-- 
2.7.4