Linux: Refactor udev device monitoring code into its own class so it can be reused more easily.

content/browser/udev_linux.cc

+// 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.
+
+#include "content/browser/udev_linux.h"
+
+#include <libudev.h>
+
+#include "base/message_loop.h"
+
+namespace content {
+
+UdevLinux::UdevLinux(const std::vector<UdevMonitorFilter>& filters,
+                     const UdevNotificationCallback& callback)
+    : udev_(udev_new()),
+      monitor_(NULL),
+      monitor_fd_(-1),
+      callback_(callback) {
+  CHECK(udev_);
+
+  monitor_ = udev_monitor_new_from_netlink(udev_, "udev");
+  CHECK(monitor_);
+
+  for (size_t i = 0; i < filters.size(); ++i) {
+    int ret = udev_monitor_filter_add_match_subsystem_devtype(
+        monitor_, filters[i].subsystem, filters[i].devtype);
+    CHECK_EQ(0, ret);
+  }
+
+  int ret = udev_monitor_enable_receiving(monitor_);
+  CHECK_EQ(0, ret);
+  monitor_fd_ = udev_monitor_get_fd(monitor_);
+  CHECK_GE(monitor_fd_, 0);
+
+  bool success = MessageLoopForIO::current()->WatchFileDescriptor(monitor_fd_,
+      true, MessageLoopForIO::WATCH_READ, &monitor_watcher_, this);
+  CHECK(success);
+}
+
+UdevLinux::~UdevLinux() {
+  monitor_watcher_.StopWatchingFileDescriptor();
+  udev_monitor_unref(monitor_);
+  udev_unref(udev_);
+}
+
+udev* UdevLinux::udev_handle() {
+  return udev_;
+}
+
+void UdevLinux::OnFileCanReadWithoutBlocking(int fd) {
+  // Events occur when devices attached to the system are added, removed, or
+  // change state. udev_monitor_receive_device() will return a device object
+  // representing the device which changed and what type of change occured.
+  DCHECK_EQ(monitor_fd_, fd);
+  udev_device* dev = udev_monitor_receive_device(monitor_);
+  if (!dev) {
+    NOTREACHED();
+    return;
+  }
+  callback_.Run(dev);
+  udev_device_unref(dev);
+}
+
+void UdevLinux::OnFileCanWriteWithoutBlocking(int fd) {
+}
+
+}  // namespace content