content/browser/udev_linux.h

   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
  46 extern "C" {
  47 struct udev;
  48 struct udev_device;
  49 struct udev_monitor;
  50 }
  51
  52 namespace content {
  53
  54 class 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_