Disallow calling Map on currently-mapped SharedMemory

base/memory/shared_memory_unittest.cc

 // Copyright (c) 2012 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/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "base/process/kill.h"
 #include "base/rand_util.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 459 matching lines @@
                         contents.size()));
 }
 
 TEST(SharedMemoryTest, MapAt) {
   ASSERT_TRUE(SysInfo::VMAllocationGranularity() >= sizeof(uint32));
   const size_t kCount = SysInfo::VMAllocationGranularity();
   const size_t kDataSize = kCount * sizeof(uint32);
 
   SharedMemory memory;
   ASSERT_TRUE(memory.CreateAndMapAnonymous(kDataSize));
-  ASSERT_TRUE(memory.Map(kDataSize));
   uint32* ptr = static_cast<uint32*>(memory.memory());
   ASSERT_NE(ptr, static_cast<void*>(NULL));
 
   for (size_t i = 0; i < kCount; ++i) {
     ptr[i] = i;
   }
 
   memory.Unmap();
 
   off_t offset = SysInfo::VMAllocationGranularity();
   ASSERT_TRUE(memory.MapAt(offset, kDataSize - offset));
   offset /= sizeof(uint32);
   ptr = static_cast<uint32*>(memory.memory());
   ASSERT_NE(ptr, static_cast<void*>(NULL));
   for (size_t i = offset; i < kCount; ++i) {
     EXPECT_EQ(ptr[i - offset], i);
   }
 }
 
+TEST(SharedMemoryTest, MapTwice) {
+  const uint32 kDataSize = 1024;
+  SharedMemory memory;
+  bool rv = memory.CreateAndMapAnonymous(kDataSize);
+  EXPECT_TRUE(rv);
+
+  void* old_address = memory.memory();
+
+  rv = memory.Map(kDataSize);
+  EXPECT_FALSE(rv);
+  EXPECT_EQ(old_address, memory.memory());
+}
+
 #if defined(OS_POSIX)
 // Create a shared memory object, mmap it, and mprotect it to PROT_EXEC.
 TEST(SharedMemoryTest, AnonymousExecutable) {
   const uint32 kTestSize = 1 << 16;
 
   SharedMemory shared_memory;
   SharedMemoryCreateOptions options;
   options.size = kTestSize;
   options.executable = true;
 
@@ skipping 151 matching lines @@
   SharedMemoryProcessTest::CleanUp();
 }
 
 MULTIPROCESS_TEST_MAIN(SharedMemoryTestMain) {
   return SharedMemoryProcessTest::TaskTestMain();
 }
 
 #endif  // !OS_IOS
 
 }  // namespace base