Update ReadProcMaps() to reflect lack of atomicity when reading /proc/self/maps.

base/debug/proc_maps_linux_unittest.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/debug/proc_maps_linux.h"
 #include "base/files/file_path.h"
 #include "base/path_service.h"
 #include "base/strings/stringprintf.h"
 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 162 matching lines @@
 
     std::vector<MappedMemoryRegion> regions;
     EXPECT_TRUE(ParseProcMaps(kTestCases[i].input, &regions));
     EXPECT_EQ(1u, regions.size());
     if (regions.empty())
       continue;
     EXPECT_EQ(kTestCases[i].permissions, regions[0].permissions);
   }
 }
 
-// ProcMapsTest.ReadProcMaps fails under TSan on Linux,
-// see http://crbug.com/258451.
-#if defined(THREAD_SANITIZER)
-#define MAYBE_ReadProcMaps DISABLED_ReadProcMaps
-#else
-#define MAYBE_ReadProcMaps ReadProcMaps
-#endif
-TEST(ProcMapsTest, MAYBE_ReadProcMaps) {
+TEST(ProcMapsTest, ReadProcMaps) {
   std::string proc_maps;
   ASSERT_TRUE(ReadProcMaps(&proc_maps));
 
   std::vector<MappedMemoryRegion> regions;
   ASSERT_TRUE(ParseProcMaps(proc_maps, &regions));
   ASSERT_FALSE(regions.empty());
 
   // We should be able to find both the current executable as well as the stack
   // mapped into memory. Use the address of |proc_maps| as a way of finding the
   // stack.
@@ skipping 30 matching lines @@
       EXPECT_FALSE(found_address) << "Found same address in multiple regions";
       found_address = true;
     }
   }
 
   EXPECT_TRUE(found_exe);
   EXPECT_TRUE(found_stack);
   EXPECT_TRUE(found_address);
 }
 
+TEST(ProcMapsTest, ReadProcMapsNonEmptyString) {
+  std::string old_string("I forgot to clear the string");
+  std::string proc_maps(old_string);
+  ASSERT_TRUE(ReadProcMaps(&proc_maps));
+  EXPECT_EQ(std::string::npos, proc_maps.find(old_string));
+}
+
 TEST(ProcMapsTest, MissingFields) {
   static const char* kTestCases[] = {
     "00400000\n",                               // Missing end + beyond.
     "00400000-0040b000\n",                      // Missing perms + beyond.
     "00400000-0040b000 r-xp\n",                 // Missing offset + beyond.
     "00400000-0040b000 r-xp 00000000\n",        // Missing device + beyond.
     "00400000-0040b000 r-xp 00000000 fc:00\n",  // Missing inode + beyond.
     "00400000-0040b000 00000000 fc:00 794418 /bin/cat\n",  // Missing perms.
     "00400000-0040b000 r-xp fc:00 794418 /bin/cat\n",      // Missing offset.
     "00400000-0040b000 r-xp 00000000 fc:00 /bin/cat\n",    // Missing inode.
@@ skipping 21 matching lines @@
 
   for (size_t i = 0; i < arraysize(kTestCases); ++i) {
     SCOPED_TRACE(base::StringPrintf("kTestCases[%zu] = %s", i, kTestCases[i]));
     std::vector<MappedMemoryRegion> regions;
     EXPECT_FALSE(ParseProcMaps(kTestCases[i], &regions));
   }
 }
 
 }  // namespace debug
 }  // namespace base