Implement Linux media notifier.

content/browser/media_device_notifications_linux.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_BROWSER_MEDIA_DEVICE_NOTIFICATIONS_LINUX_H_
+#define CONTENT_BROWSER_MEDIA_DEVICE_NOTIFICATIONS_LINUX_H_
+#pragma once
+
+#include <map>
+#include <set>
+#include <string>
+#include <utility>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop.h"
+#include "base/system_monitor/system_monitor.h"
+#include "content/common/content_export.h"
+
+struct inotify_event;
+
+namespace content {
+
+class CONTENT_EXPORT MediaDeviceNotificationsLinux
+    : public base::MessagePumpLibevent::Watcher,
+      public base::RefCounted<MediaDeviceNotificationsLinux> {
+ public:
+  explicit MediaDeviceNotificationsLinux(const FilePath& path);
+
+  // Must be called for MediaDeviceNotificationsLinux to work.
+  void InitOnFileThread();
+
+  // base::MessagePump:Libevent::Watcher implementation
+  virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
+  virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE;
+
+ private:
+  friend class base::RefCounted<MediaDeviceNotificationsLinux>;
+
+  typedef std::string MountDevice;
+  typedef std::string MountPoint;
+  typedef std::pair<MountPoint, MountDevice> MountEntry;
+
+  // Set of mount devices for a given mount point.
+  typedef std::set<MountDevice> MountDevices;
+
+  typedef std::map<MountPoint, MountDevices> MountMap;
+
+  // Map with key: (mount point, mount device) value: device id.
+  typedef std::map<MountEntry, base::SystemMonitor::DeviceIdType> DeviceIdMap;
+
+  virtual ~MediaDeviceNotificationsLinux();
+
+  // Helper function to close and clear |inotify_fd_|.
+  void CleanupInotifyFD();
+
+  // Process a single event from Inotify.
+  bool ProcessInotifyEvent(inotify_event* event);
+
+  // Parse the mtab file and find all changes.
+  void UpdateMtab();
+
+  // Read the mtab file entries into |mtab|.
+  void ReadMtab(MountMap* mtab);
+
+  // For a given mount point, check the new mount devices against existing
+  // known mount devices.
+  void CompareMountPointDevices(const MountPoint& mount_point,
+                                const MountDevices& new_devices,
+                                const MountDevices& old_devices);
+
+  // Add and remove media devices with a given mount point and mount device.
+  void AddNewMediaDevice(const MountPoint& mount_point,
+                         const MountDevice& mount_device);
+  void RemoveOldMediaDevice(const MountPoint& mount_point,
+                            const MountDevice& mount_device);
+
+  // Whether Init() has been called or not.
+  bool initialized_;
+
+  // The directory to watch with Inotify.
+  const FilePath watch_dir_;
+  // The file in |watch_dir_| to watch for.
+  const FilePath watch_file_;
+
+  // Inotify file descriptor and watch descriptor.
+  int inotify_fd_;
+  int inotify_wd_;
+
+  // Watcher for |inotify_fd_|.
+  base::MessagePumpLibevent::FileDescriptorWatcher inotify_watcher_;
+
+  // Mapping of relevent mount points and their corresponding mount devices.
+  // Keep in mind on Linux, a device can be mounted at multiple mount points,
+  // and multiple devices can be mounted at a mount point.
+  MountMap mtab_;
+
+  // Mapping of mount entries to unique device ids.
+  DeviceIdMap device_id_map_;
+
+  // The lowest available device id number.
+  base::SystemMonitor::DeviceIdType current_device_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaDeviceNotificationsLinux);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_MEDIA_DEVICE_NOTIFICATIONS_LINUX_H_