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(
  14     base::LINKER_INITIALIZED);
  15
  16 MemoryMappedFile::Region::Region(base::LinkerInitialized) : offset(0), size(0) {
  17 }
  18
  19 MemoryMappedFile::Region::Region() : offset(-1), size(-1) {
  20 }
  21
  22 MemoryMappedFile::Region::Region(int64 offset, int64 size)
  23     : offset(offset), size(size) {
  24 }
  25
  26 bool MemoryMappedFile::Region::operator==(
  27     const MemoryMappedFile::Region& other) const {
  28   return other.offset == offset && other.size == size;
  29 }
  30
  31 bool MemoryMappedFile::Region::operator!=(
  32     const MemoryMappedFile::Region& other) const {
  33   return other.offset != offset || other.size != size;
  34 }
  35
  36 MemoryMappedFile::~MemoryMappedFile() {
  37   CloseHandles();
  38 }
  39
  40 #if !defined(OS_NACL)
  41 bool MemoryMappedFile::Initialize(const FilePath& file_name) {
  42   if (IsValid())
  43     return false;
  44
  45   file_.Initialize(file_name, File::FLAG_OPEN | File::FLAG_READ);
  46
  47   if (!file_.IsValid()) {
  48     DLOG(ERROR) << "Couldn't open " << file_name.AsUTF8Unsafe();
  49     return false;
  50   }
  51
  52   if (!MapFileRegionToMemory(Region::kWholeFile)) {
  53     CloseHandles();
  54     return false;
  55   }
  56
  57   return true;
  58 }
  59
  60 bool MemoryMappedFile::Initialize(File file) {
  61   return Initialize(file.Pass(), Region::kWholeFile);
  62 }
  63
  64 bool MemoryMappedFile::Initialize(File file, const Region& region) {
  65   if (IsValid())
  66     return false;
  67
  68   if (region != Region::kWholeFile) {
  69     DCHECK_GE(region.offset, 0);
  70     DCHECK_GT(region.size, 0);
  71   }
  72
  73   file_ = file.Pass();
  74
  75   if (!MapFileRegionToMemory(region)) {
  76     CloseHandles();
  77     return false;
  78   }
  79
  80   return true;
  81 }
  82
  83 bool MemoryMappedFile::IsValid() const {
  84   return data_ != NULL;
  85 }
  86
  87 // static
  88 void MemoryMappedFile::CalculateVMAlignedBoundaries(int64 start,
  89                                                     int64 size,
  90                                                     int64* aligned_start,
  91                                                     int64* aligned_size,
  92                                                     int32* offset) {
  93   // Sadly, on Windows, the mmap alignment is not just equal to the page size.
  94   const int64 mask = static_cast<int64>(SysInfo::VMAllocationGranularity()) - 1;
  95   DCHECK_LT(mask, std::numeric_limits<int32>::max());
  96   *offset = start & mask;
  97   *aligned_start = start & ~mask;
  98   *aligned_size = (size + *offset + mask) & ~mask;
  99 }
 100 #endif
 101
 102 }  // namespace base