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Issue 10069007: Media Gallery: Move MediaDeviceNotificationsLinux from content to chrome. (Closed) Base URL: svn://chrome-svn/chrome/trunk/src/
Patch Set: clang Created 8 years, 8 months ago
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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 // MediaDeviceNotificationsLinux implementation.
6
7 #include "content/browser/media_device_notifications_linux.h"
8
9 #include <mntent.h>
10 #include <stdio.h>
11
12 #include <vector>
13
14 #include "base/bind.h"
15 #include "base/file_path.h"
16 #include "base/file_util.h"
17 #include "base/string_util.h"
18 #include "base/system_monitor/system_monitor.h"
19 #include "content/public/browser/browser_thread.h"
20
21 namespace {
22
23 const char kDCIMDirName[] = "DCIM";
24
25 // List of file systems we care about.
26 const char* const kKnownFileSystems[] = {
27 "ext2",
28 "ext3",
29 "ext4",
30 "fat",
31 "hfsplus",
32 "iso9660",
33 "msdos",
34 "ntfs",
35 "udf",
36 "vfat",
37 };
38
39 } // namespace
40
41 namespace content {
42
43 using base::SystemMonitor;
44
45 // A simple pass-through class. MediaDeviceNotificationsLinux cannot directly
46 // inherit from FilePathWatcher::Delegate due to multiple inheritance.
47 class MediaDeviceNotificationsLinux::WatcherDelegate
48 : public base::files::FilePathWatcher::Delegate {
49 public:
50 explicit WatcherDelegate(MediaDeviceNotificationsLinux* notifier);
51
52 // base::files::FilePathWatcher::Delegate implementation.
53 virtual void OnFilePathChanged(const FilePath& path) OVERRIDE;
54
55 private:
56 friend class base::RefCountedThreadSafe<WatcherDelegate>;
57
58 // Avoids code deleting the object while there are references to it.
59 // Aside from the base::RefCountedThreadSafe friend class, any attempts to
60 // call this dtor will result in a compile-time error.
61 virtual ~WatcherDelegate();
62
63 // The MediaDeviceNotificationsLinux instance that owns this WatcherDelegate.
64 // Since |notifier_| will destroy this WatcherDelegate before it goes away,
65 // the pointer is always valid. No need to add a reference count, as that
66 // would create a circular reference.
67 MediaDeviceNotificationsLinux* const notifier_;
68
69 DISALLOW_COPY_AND_ASSIGN(WatcherDelegate);
70 };
71
72 MediaDeviceNotificationsLinux::WatcherDelegate::WatcherDelegate(
73 MediaDeviceNotificationsLinux* notifier)
74 : notifier_(notifier) {
75 }
76
77 MediaDeviceNotificationsLinux::WatcherDelegate::~WatcherDelegate() {
78 }
79
80 void MediaDeviceNotificationsLinux::WatcherDelegate::OnFilePathChanged(
81 const FilePath& path) {
82 notifier_->OnFilePathChanged(path);
83 }
84
85 MediaDeviceNotificationsLinux::MediaDeviceNotificationsLinux(
86 const FilePath& path)
87 : initialized_(false),
88 mtab_path_(path),
89 current_device_id_(0U) {
90 CHECK(!path.empty());
91
92 // Put |kKnownFileSystems| in std::set to get O(log N) access time.
93 for (size_t i = 0; i < arraysize(kKnownFileSystems); ++i) {
94 known_file_systems_.insert(kKnownFileSystems[i]);
95 }
96 }
97
98 MediaDeviceNotificationsLinux::~MediaDeviceNotificationsLinux() {
99 }
100
101 void MediaDeviceNotificationsLinux::Init() {
102 BrowserThread::PostTask(
103 BrowserThread::FILE, FROM_HERE,
104 base::Bind(&MediaDeviceNotificationsLinux::InitOnFileThread, this));
105 }
106
107 void MediaDeviceNotificationsLinux::OnFilePathChanged(const FilePath& path) {
108 if (path != mtab_path_) {
109 // This cannot happen unless FileWatcher is buggy. Just ignore this
110 // notification and do nothing.
111 NOTREACHED();
112 return;
113 }
114
115 UpdateMtab();
116 }
117
118 void MediaDeviceNotificationsLinux::InitOnFileThread() {
119 DCHECK(!initialized_);
120 DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
121 initialized_ = true;
122
123 watcher_delegate_ = new WatcherDelegate(this);
124 if (!file_watcher_.Watch(mtab_path_, watcher_delegate_)) {
125 LOG(ERROR) << "Adding watch for " << mtab_path_.value() << " failed";
126 return;
127 }
128
129 UpdateMtab();
130 }
131
132 void MediaDeviceNotificationsLinux::UpdateMtab() {
133 DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
134
135 MountMap new_mtab;
136 ReadMtab(&new_mtab);
137
138 // Check existing mtab entries for unaccounted mount points.
139 // These mount points must have been removed in the new mtab.
140 std::vector<std::string> mount_points_to_erase;
141 for (MountMap::const_iterator it = mtab_.begin(); it != mtab_.end(); ++it) {
142 const std::string& mount_point = it->first;
143 // |mount_point| not in |new_mtab|.
144 if (new_mtab.find(mount_point) == new_mtab.end()) {
145 const SystemMonitor::DeviceIdType& device_id = it->second.second;
146 RemoveOldDevice(device_id);
147 mount_points_to_erase.push_back(mount_point);
148 }
149 }
150 // Erase the |mtab_| entries afterwards. Erasing in the loop above using the
151 // iterator is slightly more efficient, but more tricky, since calling
152 // std::map::erase() on an iterator invalidates it.
153 for (size_t i = 0; i < mount_points_to_erase.size(); ++i)
154 mtab_.erase(mount_points_to_erase[i]);
155
156 // Check new mtab entries against existing ones.
157 for (MountMap::iterator newiter = new_mtab.begin();
158 newiter != new_mtab.end();
159 ++newiter) {
160 const std::string& mount_point = newiter->first;
161 const MountDeviceAndId& mount_device_and_id = newiter->second;
162 const std::string& mount_device = mount_device_and_id.first;
163 SystemMonitor::DeviceIdType& id = newiter->second.second;
164 MountMap::iterator olditer = mtab_.find(mount_point);
165 // Check to see if it is a new mount point.
166 if (olditer == mtab_.end()) {
167 if (IsMediaDevice(mount_point)) {
168 AddNewDevice(mount_device, mount_point, &id);
169 mtab_.insert(std::make_pair(mount_point, mount_device_and_id));
170 }
171 continue;
172 }
173
174 // Existing mount point. Check to see if a new device is mounted there.
175 const MountDeviceAndId& old_mount_device_and_id = olditer->second;
176 if (mount_device == old_mount_device_and_id.first)
177 continue;
178
179 // New device mounted.
180 RemoveOldDevice(old_mount_device_and_id.second);
181 if (IsMediaDevice(mount_point)) {
182 AddNewDevice(mount_device, mount_point, &id);
183 olditer->second = mount_device_and_id;
184 }
185 }
186 }
187
188 void MediaDeviceNotificationsLinux::ReadMtab(MountMap* mtab) {
189 FILE* fp = setmntent(mtab_path_.value().c_str(), "r");
190 if (!fp)
191 return;
192
193 MountMap& new_mtab = *mtab;
194 mntent entry;
195 char buf[512];
196 SystemMonitor::DeviceIdType mount_position = 0;
197 typedef std::pair<std::string, SystemMonitor::DeviceIdType> MountPointAndId;
198 typedef std::map<std::string, MountPointAndId> DeviceMap;
199 DeviceMap device_map;
200 while (getmntent_r(fp, &entry, buf, sizeof(buf))) {
201 // We only care about real file systems.
202 if (known_file_systems_.find(entry.mnt_type) == known_file_systems_.end())
203 continue;
204 // Add entries, but overwrite entries for the same mount device. Keep track
205 // of the entry positions in the device id field and use that below to
206 // resolve multiple devices mounted at the same mount point.
207 MountPointAndId mount_point_and_id =
208 std::make_pair(entry.mnt_dir, mount_position++);
209 DeviceMap::iterator it = device_map.find(entry.mnt_fsname);
210 if (it == device_map.end()) {
211 device_map.insert(it,
212 std::make_pair(entry.mnt_fsname, mount_point_and_id));
213 } else {
214 it->second = mount_point_and_id;
215 }
216 }
217 endmntent(fp);
218
219 for (DeviceMap::const_iterator device_it = device_map.begin();
220 device_it != device_map.end();
221 ++device_it) {
222 const std::string& device = device_it->first;
223 const std::string& mount_point = device_it->second.first;
224 const SystemMonitor::DeviceIdType& position = device_it->second.second;
225
226 // No device at |mount_point|, save |device| to it.
227 MountMap::iterator mount_it = new_mtab.find(mount_point);
228 if (mount_it == new_mtab.end()) {
229 new_mtab.insert(std::make_pair(mount_point,
230 std::make_pair(device, position)));
231 continue;
232 }
233
234 // There is already a device mounted at |mount_point|. Check to see if
235 // the existing mount entry is newer than the current one.
236 std::string& existing_device = mount_it->second.first;
237 SystemMonitor::DeviceIdType& existing_position = mount_it->second.second;
238 if (existing_position > position)
239 continue;
240
241 // The current entry is newer, update the mount point entry.
242 existing_device = device;
243 existing_position = position;
244 }
245 }
246
247 bool MediaDeviceNotificationsLinux::IsMediaDevice(
248 const std::string& mount_point) {
249 FilePath dcim_path(mount_point);
250 FilePath::StringType dcim_dir = kDCIMDirName;
251 if (!file_util::DirectoryExists(dcim_path.Append(dcim_dir))) {
252 // Check for lowercase 'dcim' as well.
253 FilePath dcim_path_lower(dcim_path.Append(StringToLowerASCII(dcim_dir)));
254 if (!file_util::DirectoryExists(dcim_path_lower)) {
255 return false;
256 }
257 }
258 return true;
259 }
260
261 void MediaDeviceNotificationsLinux::AddNewDevice(
262 const std::string& mount_device,
263 const std::string& mount_point,
264 base::SystemMonitor::DeviceIdType* device_id) {
265 *device_id = current_device_id_++;
266 base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
267 system_monitor->ProcessMediaDeviceAttached(*device_id,
268 mount_device,
269 FilePath(mount_point));
270 }
271
272 void MediaDeviceNotificationsLinux::RemoveOldDevice(
273 const base::SystemMonitor::DeviceIdType& device_id) {
274 base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
275 system_monitor->ProcessMediaDeviceDetached(device_id);
276 }
277
278 } // namespace content
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