Refactor Udev device support in Ozone and add a DRM hotplug monitor

ui/events/ozone/device/udev/device_manager_udev.cc

+// Copyright 2014 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 "ui/events/ozone/device/udev/device_manager_udev.h"
+
+#include <libudev.h>
+
+#include "base/debug/trace_event.h"
+#include "base/strings/stringprintf.h"
+#include "ui/events/ozone/device/device_event.h"
+#include "ui/events/ozone/device/device_event_observer.h"
+
+namespace ui {
+
+namespace {
+
+const char* kSubsystems[] = {
+  "input",
+  "drm",
+};
+
+// Severity levels from syslog.h. We can't include it directly as it
+// conflicts with base/logging.h
+enum {
+  SYS_LOG_EMERG = 0,
+  SYS_LOG_ALERT = 1,
+  SYS_LOG_CRIT = 2,
+  SYS_LOG_ERR = 3,
+  SYS_LOG_WARNING = 4,
+  SYS_LOG_NOTICE = 5,
+  SYS_LOG_INFO = 6,
+  SYS_LOG_DEBUG = 7,
+};
+
+// Log handler for messages generated from libudev.
+void UdevLog(struct udev* udev,
+             int priority,
+             const char* file,
+             int line,
+             const char* fn,
+             const char* format,
+             va_list args) {
+  if (priority <= SYS_LOG_ERR)
+    LOG(ERROR) << "libudev: " << fn << ": " << base::StringPrintV(format, args);
+  else if (priority <= SYS_LOG_INFO)
+    VLOG(1) << "libudev: " << fn << ": " << base::StringPrintV(format, args);
+  else  // SYS_LOG_DEBUG
+    VLOG(2) << "libudev: " << fn << ": " << base::StringPrintV(format, args);
+}
+
+// Create libudev context.
+scoped_udev UdevCreate() {
+  struct udev* udev = udev_new();
+  if (udev) {
+    udev_set_log_fn(udev, UdevLog);
+    udev_set_log_priority(udev, SYS_LOG_DEBUG);
+  }
+  return scoped_udev(udev);
+}
+
+// Start monitoring input device changes.
+scoped_udev_monitor UdevCreateMonitor(struct udev* udev) {
+  struct udev_monitor* monitor = udev_monitor_new_from_netlink(udev, "udev");
+  if (monitor) {
+    for (size_t i = 0; i < arraysize(kSubsystems); ++i)
+      udev_monitor_filter_add_match_subsystem_devtype(
+          monitor, kSubsystems[i], NULL);
+
+    if (udev_monitor_enable_receiving(monitor))
+      LOG(ERROR) << "Failed to start receiving events from udev";
+  } else {
+    LOG(ERROR) << "Failed to create udev monitor";
+  }
+
+  return scoped_udev_monitor(monitor);
+}
+
+}  // namespace
+
+DeviceManagerUdev::DeviceManagerUdev()
+  : udev_(UdevCreate()),
+    monitor_(UdevCreateMonitor(udev_.get())) {
+
+  if (monitor_) {
+    int fd = udev_monitor_get_fd(monitor_.get());
+    CHECK_GT(fd, 0);
+    base::MessageLoopForUI::current()->WatchFileDescriptor(
+        fd, true, base::MessagePumpLibevent::WATCH_READ, &controller_, this);
+  }
+}
+
+DeviceManagerUdev::~DeviceManagerUdev() {}
+
+void DeviceManagerUdev::ScanDevices(DeviceEventObserver* observer) {
+  scoped_udev_enumerate enumerate(udev_enumerate_new(udev_.get()));
+  if (!enumerate)
+    return;
+
+  for (size_t i = 0; i < arraysize(kSubsystems); ++i)
+    udev_enumerate_add_match_subsystem(enumerate.get(), kSubsystems[i]);
+  udev_enumerate_scan_devices(enumerate.get());
+
+  struct udev_list_entry* devices =
+      udev_enumerate_get_list_entry(enumerate.get());
+  struct udev_list_entry* entry;
+
+  udev_list_entry_foreach(entry, devices) {
+    scoped_udev_device device(udev_device_new_from_syspath(
+        udev_.get(), udev_list_entry_get_name(entry)));
+    if (!device)
+      continue;
+
+    scoped_ptr<DeviceEvent> event = ProcessMessage(device.get());
+    if (event)
+      observer->OnDeviceEvent(*event.get());
+  }
+}
+
+void DeviceManagerUdev::AddObserver(DeviceEventObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void DeviceManagerUdev::RemoveObserver(DeviceEventObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void DeviceManagerUdev::OnFileCanReadWithoutBlocking(int fd) {
+  // The netlink socket should never become disconnected. There's no need
+  // to handle broken connections here.
+  TRACE_EVENT1("ozone", "UdevDeviceChange", "socket", fd);
+
+  scoped_udev_device device(udev_monitor_receive_device(monitor_.get()));
+  if (!device)
+    return;
+
+  scoped_ptr<DeviceEvent> event = ProcessMessage(device.get());
+  if (event)
+    FOR_EACH_OBSERVER(
+        DeviceEventObserver, observers_, OnDeviceEvent(*event.get()));
+}
+
+void DeviceManagerUdev::OnFileCanWriteWithoutBlocking(int fd) {
+  NOTREACHED();
+}
+
+scoped_ptr<DeviceEvent> DeviceManagerUdev::ProcessMessage(udev_device* device) {
+  const char* path = udev_device_get_devnode(device);
+  const char* action = udev_device_get_action(device);
+  const char* hotplug = udev_device_get_property_value(device, "HOTPLUG");
+  const char* subsystem = udev_device_get_property_value(device, "SUBSYSTEM");
+
+  if (!path || !subsystem)
+    return scoped_ptr<DeviceEvent>();
+
+  DeviceEvent::DeviceType device_type;
+  if (!strcmp(subsystem, "input") &&
+      StartsWithASCII(path, "/dev/input/event", true))
+    device_type = DeviceEvent::INPUT;
+  else if (!strcmp(subsystem, "drm") && hotplug && !strcmp(hotplug, "1"))
+    device_type = DeviceEvent::DISPLAY;
+  else
+    return scoped_ptr<DeviceEvent>();
+
+  DeviceEvent::ActionType action_type;
+  if (!action || !strcmp(action, "add"))
+    action_type = DeviceEvent::ADD;
+  else if (!strcmp(action, "remove"))
+    action_type = DeviceEvent::REMOVE;
+  else if (!strcmp(action, "change"))
+    action_type = DeviceEvent::CHANGE;
+  else
+    return scoped_ptr<DeviceEvent>();
+
+  return scoped_ptr<DeviceEvent>(
+      new DeviceEvent(device_type, action_type, base::FilePath(path)));
+}
+
+}  // namespace ui