1 files changed, 95 insertions, 0 deletions
diff --git a/base/files/memory_mapped_file.cc b/base/files/memory_mapped_file.cc
new file mode 100644
index 0000000000..0fd9d6796b
--- /dev/null
+++ b/base/files/memory_mapped_file.cc
@@ -0,0 +1,95 @@
+// Copyright 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/files/memory_mapped_file.h"
+
+#include <utility>
+
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/sys_info.h"
+#include "build/build_config.h"
+
+namespace base {
+
+const MemoryMappedFile::Region MemoryMappedFile::Region::kWholeFile = {0, 0};
+
+bool MemoryMappedFile::Region::operator==(
+    const MemoryMappedFile::Region& other) const {
+  return other.offset == offset && other.size == size;
+}
+
+bool MemoryMappedFile::Region::operator!=(
+    const MemoryMappedFile::Region& other) const {
+  return other.offset != offset || other.size != size;
+}
+
+MemoryMappedFile::~MemoryMappedFile() {
+  CloseHandles();
+}
+
+#if !defined(OS_NACL)
+bool MemoryMappedFile::Initialize(const FilePath& file_name) {
+  if (IsValid())
+    return false;
+
+  file_.Initialize(file_name, File::FLAG_OPEN | File::FLAG_READ);
+
+  if (!file_.IsValid()) {
+    DLOG(ERROR) << "Couldn't open " << file_name.AsUTF8Unsafe();
+    return false;
+  }
+
+  if (!MapFileRegionToMemory(Region::kWholeFile)) {
+    CloseHandles();
+    return false;
+  }
+
+  return true;
+}
+
+bool MemoryMappedFile::Initialize(File file) {
+  return Initialize(std::move(file), Region::kWholeFile);
+}
+
+bool MemoryMappedFile::Initialize(File file, const Region& region) {
+  if (IsValid())
+    return false;
+
+  if (region != Region::kWholeFile) {
+    DCHECK_GE(region.offset, 0);
+    DCHECK_GT(region.size, 0);
+  }
+
+  file_ = std::move(file);
+
+  if (!MapFileRegionToMemory(region)) {
+    CloseHandles();
+    return false;
+  }
+
+  return true;
+}
+
+bool MemoryMappedFile::IsValid() const {
+  return data_ != NULL;
+}
+
+// static
+void MemoryMappedFile::CalculateVMAlignedBoundaries(int64_t start,
+                                                    int64_t size,
+                                                    int64_t* aligned_start,
+                                                    int64_t* aligned_size,
+                                                    int32_t* offset) {
+  // Sadly, on Windows, the mmap alignment is not just equal to the page size.
+  const int64_t mask =
+      static_cast<int64_t>(SysInfo::VMAllocationGranularity()) - 1;
+  DCHECK_LT(mask, std::numeric_limits<int32_t>::max());
+  *offset = start & mask;
+  *aligned_start = start & ~mask;
+  *aligned_size = (size + *offset + mask) & ~mask;
+}
+#endif
+
+}  // namespace base