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 <utility>
8
9 #include "base/files/file_path.h"
10 #include "base/logging.h"
11 #include "base/sys_info.h"
12 #include "build/build_config.h"
13
14 namespace base {
15
16 const MemoryMappedFile::Region MemoryMappedFile::Region::kWholeFile = {0, 0};
17
operator ==(const MemoryMappedFile::Region & other) const18 bool MemoryMappedFile::Region::operator==(
19 const MemoryMappedFile::Region& other) const {
20 return other.offset == offset && other.size == size;
21 }
22
operator !=(const MemoryMappedFile::Region & other) const23 bool MemoryMappedFile::Region::operator!=(
24 const MemoryMappedFile::Region& other) const {
25 return other.offset != offset || other.size != size;
26 }
27
~MemoryMappedFile()28 MemoryMappedFile::~MemoryMappedFile() {
29 CloseHandles();
30 }
31
32 #if !defined(OS_NACL)
Initialize(const FilePath & file_name,Access access)33 bool MemoryMappedFile::Initialize(const FilePath& file_name, Access access) {
34 if (IsValid())
35 return false;
36
37 uint32_t flags = 0;
38 switch (access) {
39 case READ_ONLY:
40 flags = File::FLAG_OPEN | File::FLAG_READ;
41 break;
42 case READ_WRITE:
43 flags = File::FLAG_OPEN | File::FLAG_READ | File::FLAG_WRITE;
44 break;
45 case READ_WRITE_EXTEND:
46 // Can't open with "extend" because no maximum size is known.
47 NOTREACHED();
48 }
49 file_.Initialize(file_name, flags);
50
51 if (!file_.IsValid()) {
52 DLOG(ERROR) << "Couldn't open " << file_name.AsUTF8Unsafe();
53 return false;
54 }
55
56 if (!MapFileRegionToMemory(Region::kWholeFile, access)) {
57 CloseHandles();
58 return false;
59 }
60
61 return true;
62 }
63
Initialize(File file,Access access)64 bool MemoryMappedFile::Initialize(File file, Access access) {
65 DCHECK_NE(READ_WRITE_EXTEND, access);
66 return Initialize(std::move(file), Region::kWholeFile, access);
67 }
68
Initialize(File file,const Region & region,Access access)69 bool MemoryMappedFile::Initialize(File file,
70 const Region& region,
71 Access access) {
72 switch (access) {
73 case READ_WRITE_EXTEND:
74 // Ensure that the extended size is within limits of File.
75 if (region.size > std::numeric_limits<int64_t>::max() - region.offset) {
76 DLOG(ERROR) << "Region bounds exceed maximum for base::File.";
77 return false;
78 }
79 // Fall through.
80 case READ_ONLY:
81 case READ_WRITE:
82 // Ensure that the region values are valid.
83 if (region.offset < 0 || region.size < 0) {
84 DLOG(ERROR) << "Region bounds are not valid.";
85 return false;
86 }
87 break;
88 }
89
90 if (IsValid())
91 return false;
92
93 if (region != Region::kWholeFile) {
94 DCHECK_GE(region.offset, 0);
95 DCHECK_GT(region.size, 0);
96 }
97
98 file_ = std::move(file);
99
100 if (!MapFileRegionToMemory(region, access)) {
101 CloseHandles();
102 return false;
103 }
104
105 return true;
106 }
107
IsValid() const108 bool MemoryMappedFile::IsValid() const {
109 return data_ != NULL;
110 }
111
112 // static
CalculateVMAlignedBoundaries(int64_t start,int64_t size,int64_t * aligned_start,int64_t * aligned_size,int32_t * offset)113 void MemoryMappedFile::CalculateVMAlignedBoundaries(int64_t start,
114 int64_t size,
115 int64_t* aligned_start,
116 int64_t* aligned_size,
117 int32_t* offset) {
118 // Sadly, on Windows, the mmap alignment is not just equal to the page size.
119 const int64_t mask =
120 static_cast<int64_t>(SysInfo::VMAllocationGranularity()) - 1;
121 DCHECK_LT(mask, std::numeric_limits<int32_t>::max());
122 *offset = start & mask;
123 *aligned_start = start & ~mask;
124 *aligned_size = (size + *offset + mask) & ~mask;
125 }
126 #endif
127
128 } // namespace base
129