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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 // 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_
     98