1// Copyright 2013 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "base/files/memory_mapped_file.h"
6
7#include "base/files/file_path.h"
8#include "base/logging.h"
9#include "base/sys_info.h"
10
11namespace base {
12
13const MemoryMappedFile::Region MemoryMappedFile::Region::kWholeFile(
14    base::LINKER_INITIALIZED);
15
16MemoryMappedFile::Region::Region(base::LinkerInitialized) : offset(0), size(0) {
17}
18
19MemoryMappedFile::Region::Region(int64 offset, int64 size)
20    : offset(offset), size(size) {
21  DCHECK_GE(offset, 0);
22  DCHECK_GT(size, 0);
23}
24
25bool MemoryMappedFile::Region::operator==(
26    const MemoryMappedFile::Region& other) const {
27  return other.offset == offset && other.size == size;
28}
29
30MemoryMappedFile::~MemoryMappedFile() {
31  CloseHandles();
32}
33
34bool MemoryMappedFile::Initialize(const FilePath& file_name) {
35  if (IsValid())
36    return false;
37
38  file_.Initialize(file_name, File::FLAG_OPEN | File::FLAG_READ);
39
40  if (!file_.IsValid()) {
41    DLOG(ERROR) << "Couldn't open " << file_name.AsUTF8Unsafe();
42    return false;
43  }
44
45  if (!MapFileRegionToMemory(Region::kWholeFile)) {
46    CloseHandles();
47    return false;
48  }
49
50  return true;
51}
52
53bool MemoryMappedFile::Initialize(File file) {
54  return Initialize(file.Pass(), Region::kWholeFile);
55}
56
57bool MemoryMappedFile::Initialize(File file, const Region& region) {
58  if (IsValid())
59    return false;
60
61  file_ = file.Pass();
62
63  if (!MapFileRegionToMemory(region)) {
64    CloseHandles();
65    return false;
66  }
67
68  return true;
69}
70
71bool MemoryMappedFile::IsValid() const {
72  return data_ != NULL;
73}
74
75// static
76void MemoryMappedFile::CalculateVMAlignedBoundaries(int64 start,
77                                                    int64 size,
78                                                    int64* aligned_start,
79                                                    int64* aligned_size,
80                                                    int32* offset) {
81  // Sadly, on Windows, the mmap alignment is not just equal to the page size.
82  const int64 mask = static_cast<int64>(SysInfo::VMAllocationGranularity()) - 1;
83  DCHECK_LT(mask, std::numeric_limits<int32>::max());
84  *offset = start & mask;
85  *aligned_start = start & ~mask;
86  *aligned_size = (size + *offset + mask) & ~mask;
87}
88
89}  // namespace base
90