Added SharedMemory::MapFrom.

base/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"
 #if defined(OS_MACOSX)
 #include "base/mac/scoped_nsautorelease_pool.h"
 #endif
 #include "base/memory/scoped_ptr.h"
 #include "base/shared_memory.h"
+#include "base/sys_info.h"
 #include "base/test/multiprocess_test.h"
 #include "base/threading/platform_thread.h"
 #include "base/time.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/multiprocess_func_list.h"
 
 #if defined(OS_MACOSX)
 #include "base/mac/scoped_nsautorelease_pool.h"
 #endif
 
@@ skipping 315 matching lines @@
       else
         EXPECT_EQ(0, pointers[j][0]);
     }
   }
 
   for (int i = 0; i < count; i++) {
     memories[i].Close();
   }
 }
 
+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);
+  }
+}
+
 #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 85 matching lines @@
   SharedMemoryProcessTest::CleanUp();
 }
 
 MULTIPROCESS_TEST_MAIN(SharedMemoryTestMain) {
   return SharedMemoryProcessTest::TaskTestMain();
 }
 
 #endif  // !OS_IOS
 
 }  // namespace base