[compiler-rt] r334881 - [sanitizer_common] Use O_TRUNC for WrOnly access mode.

[Fangrui Song via llvm-commits]

Author: maskray
Date: Fri Jun 15 20:32:59 2018
New Revision: 334881

URL: http://llvm.org/viewvc/llvm-project?rev=334881&view=rev
Log:
[sanitizer_common] Use O_TRUNC for WrOnly access mode.

Summary: Otherwise if the file existed and was larger than the write size before the OpenFile call, the file will not be truncated and contain garbage in trailing bytes.

Reviewers: glider, kcc, vitalybuka

Subscribers: kubamracek, delcypher, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D48250

Modified:
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_rtems.cc
    compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_libc_test.cc

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc?rev=334881&r1=334880&r2=334881&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc Fri Jun 15 20:32:59 2018
@@ -160,7 +160,7 @@ fd_t OpenFile(const char *filename, File
   int flags;
   switch (mode) {
     case RdOnly: flags = O_RDONLY; break;
-    case WrOnly: flags = O_WRONLY | O_CREAT; break;
+    case WrOnly: flags = O_WRONLY | O_CREAT | O_TRUNC; break;
     case RdWr: flags = O_RDWR | O_CREAT; break;
   }
   fd_t res = internal_open(filename, flags, 0660);

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_rtems.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_rtems.cc?rev=334881&r1=334880&r2=334881&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_rtems.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_rtems.cc Fri Jun 15 20:32:59 2018
@@ -193,7 +193,7 @@ fd_t OpenFile(const char *filename, File
   int flags;
   switch (mode) {
     case RdOnly: flags = O_RDONLY; break;
-    case WrOnly: flags = O_WRONLY | O_CREAT; break;
+    case WrOnly: flags = O_WRONLY | O_CREAT | O_TRUNC; break;
     case RdWr: flags = O_RDWR | O_CREAT; break;
   }
   fd_t res = open(filename, flags, 0660);

Modified: compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_libc_test.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_libc_test.cc?rev=334881&r1=334880&r2=334881&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_libc_test.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_libc_test.cc Fri Jun 15 20:32:59 2018
@@ -108,6 +108,12 @@ TEST(SanitizerCommon, FileOps) {
   temp_file_name(tmpfile, sizeof(tmpfile), "sanitizer_common.fileops.tmp.");
   fd_t fd = OpenFile(tmpfile, WrOnly);
   ASSERT_NE(fd, kInvalidFd);
+  ASSERT_FALSE(internal_iserror(internal_write(fd, "A", 1)));
+  CloseFile(fd);
+
+  fd = OpenFile(tmpfile, WrOnly);
+  ASSERT_NE(fd, kInvalidFd);
+  EXPECT_EQ(internal_lseek(fd, 0, SEEK_END), 0u);
   uptr bytes_written = 0;
   EXPECT_TRUE(WriteToFile(fd, str1, len1, &bytes_written));
   EXPECT_EQ(len1, bytes_written);