components/storage_monitor/mtab_watcher_linux.cc

   1 // Copyright 2014 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 // MtabWatcherLinux implementation.
   6
   7 #include "components/storage_monitor/mtab_watcher_linux.h"
   8
   9 #include <mntent.h>
  10 #include <stdio.h>
  11
  12 #include "base/bind.h"
  13 #include "content/public/browser/browser_thread.h"
  14
  15 namespace {
  16
  17 // List of file systems we care about.
  18 const char* const kKnownFileSystems[] = {
  19   "btrfs",
  20   "ext2",
  21   "ext3",
  22   "ext4",
  23   "fat",
  24   "hfsplus",
  25   "iso9660",
  26   "msdos",
  27   "ntfs",
  28   "udf",
  29   "vfat",
  30 };
  31
  32 }  // namespace
  33
  34 namespace storage_monitor {
  35
  36 MtabWatcherLinux::MtabWatcherLinux(const base::FilePath& mtab_path,
  37                                    base::WeakPtr<Delegate> delegate)
  38     : mtab_path_(mtab_path),
  39       delegate_(delegate),
  40       weak_ptr_factory_(this) {
  41   DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
  42   bool ret = file_watcher_.Watch(
  43       mtab_path_, false,
  44       base::Bind(&MtabWatcherLinux::OnFilePathChanged,
  45                  weak_ptr_factory_.GetWeakPtr()));
  46   if (!ret) {
  47     LOG(ERROR) << "Adding watch for " << mtab_path_.value() << " failed";
  48     return;
  49   }
  50
  51   ReadMtab();
  52 }
  53
  54 MtabWatcherLinux::~MtabWatcherLinux() {
  55   DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
  56 }
  57
  58 void MtabWatcherLinux::ReadMtab() const {
  59   DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
  60
  61   FILE* fp = setmntent(mtab_path_.value().c_str(), "r");
  62   if (!fp)
  63     return;
  64
  65   MountPointDeviceMap device_map;
  66   mntent entry;
  67   char buf[512];
  68
  69   // We return the same device mounted to multiple locations, but hide
  70   // devices that have been mounted over.
  71   while (getmntent_r(fp, &entry, buf, sizeof(buf))) {
  72     // We only care about real file systems.
  73     for (size_t i = 0; i < arraysize(kKnownFileSystems); ++i) {
  74       if (strcmp(kKnownFileSystems[i], entry.mnt_type) == 0) {
  75         device_map[base::FilePath(entry.mnt_dir)] =
  76             base::FilePath(entry.mnt_fsname);
  77         break;
  78       }
  79     }
  80   }
  81   endmntent(fp);
  82
  83   content::BrowserThread::PostTask(
  84       content::BrowserThread::UI, FROM_HERE,
  85       base::Bind(&Delegate::UpdateMtab, delegate_, device_map));
  86 }
  87
  88 void MtabWatcherLinux::OnFilePathChanged(
  89     const base::FilePath& path, bool error) {
  90   DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
  91
  92   if (path != mtab_path_) {
  93     // This cannot happen unless FilePathWatcher is buggy. Just ignore this
  94     // notification and do nothing.
  95     NOTREACHED();
  96     return;
  97   }
  98   if (error) {
  99     LOG(ERROR) << "Error watching " << mtab_path_.value();
 100     return;
 101   }
 102
 103   ReadMtab();
 104 }
 105
 106 }  // namespace storage_monitor