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      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(int64 offset, int64 size)
     20     : offset(offset), size(size) {
     21   DCHECK_GE(offset, 0);
     22   DCHECK_GT(size, 0);
     23 }
     24 
     25 bool MemoryMappedFile::Region::operator==(
     26     const MemoryMappedFile::Region& other) const {
     27   return other.offset == offset && other.size == size;
     28 }
     29 
     30 MemoryMappedFile::~MemoryMappedFile() {
     31   CloseHandles();
     32 }
     33 
     34 bool 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 
     53 bool MemoryMappedFile::Initialize(File file) {
     54   return Initialize(file.Pass(), Region::kWholeFile);
     55 }
     56 
     57 bool 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 
     71 bool MemoryMappedFile::IsValid() const {
     72   return data_ != NULL;
     73 }
     74 
     75 // static
     76 void 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