base/files/memory_mapped_file.cc

   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
  11 namespace base {
  12
  13 const MemoryMappedFile::Region MemoryMappedFile::Region::kWholeFile = {0, 0};
  14
  15 bool MemoryMappedFile::Region::operator==(
  16     const MemoryMappedFile::Region& other) const {
  17   return other.offset == offset && other.size == size;
  18 }
  19
  20 bool MemoryMappedFile::Region::operator!=(
  21     const MemoryMappedFile::Region& other) const {
  22   return other.offset != offset || other.size != size;
  23 }
  24
  25 MemoryMappedFile::~MemoryMappedFile() {
  26   CloseHandles();
  27 }
  28
  29 #if !defined(OS_NACL)
  30 bool MemoryMappedFile::Initialize(const FilePath& file_name) {
  31   if (IsValid())
  32     return false;
  33
  34   file_.Initialize(file_name, File::FLAG_OPEN | File::FLAG_READ);
  35
  36   if (!file_.IsValid()) {
  37     DLOG(ERROR) << "Couldn't open " << file_name.AsUTF8Unsafe();
  38     return false;
  39   }
  40
  41   if (!MapFileRegionToMemory(Region::kWholeFile)) {
  42     CloseHandles();
  43     return false;
  44   }
  45
  46   return true;
  47 }
  48
  49 bool MemoryMappedFile::Initialize(File file) {
  50   return Initialize(file.Pass(), Region::kWholeFile);
  51 }
  52
  53 bool MemoryMappedFile::Initialize(File file, const Region& region) {
  54   if (IsValid())
  55     return false;
  56
  57   if (region != Region::kWholeFile) {
  58     DCHECK_GE(region.offset, 0);
  59     DCHECK_GT(region.size, 0);
  60   }
  61
  62   file_ = file.Pass();
  63
  64   if (!MapFileRegionToMemory(region)) {
  65     CloseHandles();
  66     return false;
  67   }
  68
  69   return true;
  70 }
  71
  72 bool MemoryMappedFile::IsValid() const {
  73   return data_ != NULL;
  74 }
  75
  76 // static
  77 void MemoryMappedFile::CalculateVMAlignedBoundaries(int64 start,
  78                                                     int64 size,
  79                                                     int64* aligned_start,
  80                                                     int64* aligned_size,
  81                                                     int32* offset) {
  82   // Sadly, on Windows, the mmap alignment is not just equal to the page size.
  83   const int64 mask = static_cast<int64>(SysInfo::VMAllocationGranularity()) - 1;
  84   DCHECK_LT(mask, std::numeric_limits<int32>::max());
  85   *offset = start & mask;
  86   *aligned_start = start & ~mask;
  87   *aligned_size = (size + *offset + mask) & ~mask;
  88 }
  89 #endif
  90
  91 }  // namespace base