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// UdevLinux listens for device change notifications from udev and runs
6// callbacks when notifications occur.
7//
8// UdevLinux must be created on a MessageLoop of TYPE_IO.
9// UdevLinux is not thread-safe.
10//
11// Example usage:
12//
13// class UdevLinux;
14//
15// class Foo {
16//  public:
17//   Foo() {
18//     std::vector<UdevLinux::UdevMonitorFilter> filters;
19//     filters.push_back(content::UdevLinux::UdevMonitorFilter("block", NULL));
20//     udev_.reset(new UdevLinux(filters,
21//                               base::Bind(&Foo::Notify, this)));
22//   }
23//
24//   // Called when a "block" device attaches/detaches.
25//   // To hold on to |device|, call udev_device_ref(device).
26//   void Notify(udev_device* device) {
27//     // Do something with |device|.
28//   }
29//
30//  private:
31//   scoped_ptr<UdevLinux> udev_;
32//
33//   DISALLOW_COPY_AND_ASSIGN(Foo);
34// };
35
36#ifndef CONTENT_BROWSER_UDEV_LINUX_H_
37#define CONTENT_BROWSER_UDEV_LINUX_H_
38
39#include <vector>
40
41#include "base/basictypes.h"
42#include "base/callback.h"
43#include "base/compiler_specific.h"
44#include "base/message_loop/message_pump_libevent.h"
45
46extern "C" {
47struct udev;
48struct udev_device;
49struct udev_monitor;
50}
51
52namespace content {
53
54class UdevLinux : public base::MessagePumpLibevent::Watcher {
55 public:
56  typedef base::Callback<void(udev_device*)> UdevNotificationCallback;
57
58  // subsystem and devtype parameter for
59  // udev_monitor_filter_add_match_subsystem_devtype().
60  struct UdevMonitorFilter {
61    UdevMonitorFilter(const char* subsystem_in, const char* devtype_in)
62        : subsystem(subsystem_in),
63          devtype(devtype_in) {
64    }
65    const char* subsystem;
66    const char* devtype;
67  };
68
69  // Filter incoming devices based on |filters|.
70  // Calls |callback| upon device change events.
71  UdevLinux(const std::vector<UdevMonitorFilter>& filters,
72            const UdevNotificationCallback& callback);
73  virtual ~UdevLinux();
74
75
76  // Returns the udev handle to be passed into other udev_*() functions.
77  udev* udev_handle();
78
79 private:
80  // base::MessagePump:Libevent::Watcher implementation.
81  virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
82  virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE;
83
84  // libudev-related items, the main context, and the monitoring context to be
85  // notified about changes to device states.
86  udev* udev_;
87  udev_monitor* monitor_;
88  int monitor_fd_;
89  base::MessagePumpLibevent::FileDescriptorWatcher monitor_watcher_;
90  UdevNotificationCallback callback_;
91
92  DISALLOW_COPY_AND_ASSIGN(UdevLinux);
93};
94
95}  // namespace content
96
97#endif  // CONTENT_BROWSER_UDEV_LINUX_H_
98