net/disk_cache/mapped_file_posix.cc

   1 // Copyright (c) 2012 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 "net/disk_cache/mapped_file.h"
   6
   7 #include <errno.h>
   8 #include <sys/mman.h>
   9
  10 #include "base/files/file_path.h"
  11 #include "base/logging.h"
  12 #include "net/disk_cache/disk_cache.h"
  13
  14 namespace disk_cache {
  15
  16 void* MappedFile::Init(const base::FilePath& name, size_t size) {
  17   DCHECK(!init_);
  18   if (init_ || !File::Init(name))
  19     return NULL;
  20
  21   size_t temp_len = size ? size : 4096;
  22   if (!size)
  23     size = GetLength();
  24
  25   buffer_ = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED,
  26                  platform_file(), 0);
  27   init_ = true;
  28   view_size_ = size;
  29   DCHECK(reinterpret_cast<intptr_t>(buffer_) != -1);
  30   if (reinterpret_cast<intptr_t>(buffer_) == -1)
  31     buffer_ = 0;
  32
  33   // Make sure we detect hardware failures reading the headers.
  34   scoped_ptr<char[]> temp(new char[temp_len]);
  35   if (!Read(temp.get(), temp_len, 0))
  36     return NULL;
  37
  38   return buffer_;
  39 }
  40
  41 void MappedFile::Flush() {
  42 }
  43
  44 MappedFile::~MappedFile() {
  45   if (!init_)
  46     return;
  47
  48   if (buffer_) {
  49     int ret = munmap(buffer_, view_size_);
  50     DCHECK_EQ(0, ret);
  51   }
  52 }
  53
  54 }  // namespace disk_cache