add device notification to Mac

content/browser/device_monitor_mac.mm

+// 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/device_monitor_mac.h"
+
+#include <CoreFoundation/CFNumber.h>
+#include <CoreFoundation/CoreFoundation.h>
+#include <IOKit/usb/IOUSBLib.h>
+
+#include "base/logging.h"
+
+namespace content {
+
+namespace {
+
+DeviceMonitorMac* InstanceFromContext(void* context) {

[Avi (use Gerrit), 2012/08/03 19:41:23]

Does this help in readability? I'd think folding it into the two callers is
clearer.

[no longer working on chromium, 2012/08/06 09:43:12]

Done.

+  return reinterpret_cast<DeviceMonitorMac*>(context);
+}
+
+void AddValueToDictionary(CFMutableDictionaryRef dictionary,

[Avi (use Gerrit), 2012/08/03 19:41:23]

Ditto. If you use scoped_cftyperef, this collapses to two lines, which would
make CreateMachingDictionary much easier to read.

[no longer working on chromium, 2012/08/06 09:43:12]

Done.

+                          SInt32 code,
+                          const void *key) {
+  CFNumberRef number_ref = CFNumberCreate(kCFAllocatorDefault,

[Avi (use Gerrit), 2012/08/03 19:41:23]

scoped_cftyperef.

[no longer working on chromium, 2012/08/06 09:43:12]

Done.

+                                          kCFNumberSInt32Type,
+                                          &code);
+  if (!number_ref) {
+    NOTREACHED() << "failed to create CFNumberRef for " << code;
+    return;
+  }
+
+  CFDictionaryAddValue(dictionary, key, number_ref);
+  CFRelease(number_ref);
+}
+
+CFMutableDictionaryRef CreateMachingDictionary(SInt32 interface_class_code,

[Avi (use Gerrit), 2012/08/03 19:41:23]

s/CreateMachingDictionary/CreateMatchingDictionary/

[no longer working on chromium, 2012/08/06 09:43:12]

Done.

+                                               SInt32 interface_subclass_code) {
+  CFMutableDictionaryRef matching_dictionary = IOServiceMatching(
+      kIOUSBInterfaceClassName);
+  AddValueToDictionary(matching_dictionary, interface_class_code,
+                       CFSTR(kUSBInterfaceClass));
+  AddValueToDictionary(matching_dictionary, interface_subclass_code,
+                       CFSTR(kUSBInterfaceSubClass));
+
+  return matching_dictionary;
+}
+
+void AddCallbackToIOService(IONotificationPortRef port,
+                            const io_name_t type,
+                            CFMutableDictionaryRef dictionary,
+                            IOServiceMatchingCallback callback,
+                            void* context) {
+  // Retain additional dictionary references because each call to
+  // IOServiceAddMatchingNotification consumes one reference.
+  dictionary = (CFMutableDictionaryRef)(CFRetain(dictionary));

[Avi (use Gerrit), 2012/08/03 19:41:23]

Huh? Just do

CFRetain(dictionary);

Why do you feel the need to capture the return value?

[no longer working on chromium, 2012/08/06 09:43:12]

From the silly example code, removed.

[Avi (use Gerrit), 2012/08/06 13:54:37]

This is not removed in the latest snapshot.

+
+  io_iterator_t devices_iterator = 0;
+  kern_return_t err = IOServiceAddMatchingNotification(port,
+                                                       type,
+                                                       dictionary,
+                                                       callback,
+                                                       context,
+                                                       &devices_iterator);
+  if (err) {
+    NOTREACHED() << "Failed to register the IO mached notification for type "
+                 << type;
+    return;
+  }
+
+  // Iterate over set of matching devices to access already-present devices
+  // and to arm the notification.
+  io_object_t thisObject;

[Avi (use Gerrit), 2012/08/03 19:41:23]

base::mac::ScopedIOObject<io_object_t>? Also, this is a C function; use
this_object.

For reference, look up the use of IOIteratorNext in
chrome/browser/mac/install_from_dmg.mm to see the style.

[no longer working on chromium, 2012/08/06 09:43:12]

Done.

+  while ((thisObject = IOIteratorNext(devices_iterator)))
+    IOObjectRelease(thisObject);
+}
+
+}  // namespace
+
+DeviceMonitorMac::DeviceMonitorMac() {
+  CFRunLoopRef runloop = CFRunLoopGetCurrent();
+  CFRetain(runloop);

[Avi (use Gerrit), 2012/08/03 19:41:23]

Why the retain?

[no longer working on chromium, 2012/08/06 09:43:12]

Sorry, uncleaned debugging code. 

[Avi (use Gerrit), 2012/08/06 13:54:37]

This isn't fixed in the latest snapshot either.

+
+  // Add the notification port to the run loop.
+  IONotificationPortRef notification_port =
+      IONotificationPortCreate(kIOMasterPortDefault);

[Avi (use Gerrit), 2012/08/03 19:41:23]

Where is the matching IONotificationPortDestroy?

[no longer working on chromium, 2012/08/06 09:43:12]

Oh, thanks for pointing out, that example code I was look at does not call
IONotificationPortDestroy, so I missed it.

+  CFRunLoopSourceRef notification_cfsource =
+      IONotificationPortGetRunLoopSource(notification_port);
+
+  RegisterVideoCallbacks(notification_port);
+  RegisterAudioCallbacks(notification_port);
+  CFRunLoopAddSource(runloop, notification_cfsource, kCFRunLoopCommonModes);
+}
+
+void DeviceMonitorMac::RegisterVideoCallbacks(IONotificationPortRef port) {
+  CFMutableDictionaryRef matching_dictionary = CreateMachingDictionary(
+      kUSBVideoInterfaceClass, kUSBVideoControlSubClass);
+
+  // Add a callback which will be called when a video device is plugged in.
+  AddCallbackToIOService(port,
+                         kIOMatchedNotification,
+                         matching_dictionary,
+                         &VideoDeviceChangedCallback,
+                         this);
+
+
+  // Add a callback which will be called when a video device is terminated.
+  AddCallbackToIOService(port,
+                         kIOTerminatedNotification,
+                         matching_dictionary,
+                         &VideoDeviceChangedCallback,
+                         this);
+}
+
+void DeviceMonitorMac::RegisterAudioCallbacks(IONotificationPortRef port) {
+  CFMutableDictionaryRef matching_dictionary = CreateMachingDictionary(
+      kUSBAudioInterfaceClass, kUSBAudioControlSubClass);
+
+  // Add a callback which will be called when a audio device is plugged in.
+  AddCallbackToIOService(port,
+                         kIOMatchedNotification,
+                         matching_dictionary,
+                         &AudioDeviceChangedCallback,
+                         this);
+
+  // Add a callback which will be called when a audio device is terminated.
+  AddCallbackToIOService(port,
+                         kIOTerminatedNotification,
+                         matching_dictionary,
+                         &AudioDeviceChangedCallback,
+                         this);
+}
+
+void DeviceMonitorMac::VideoDeviceChangedCallback(void *context,
+                                                  io_iterator_t devices) {
+  io_object_t thisObject;
+  while ((thisObject = IOIteratorNext(devices))) {

[Avi (use Gerrit), 2012/08/03 19:41:23]

See previous note about IOIteratorNext.

[no longer working on chromium, 2012/08/06 09:43:12]

Done.

+    if (context) {
+      InstanceFromContext(context)->NotifyDeviceChanged(
+          base::SystemMonitor::DEVTYPE_VIDEO_CAPTURE);
+    }
+    IOObjectRelease(thisObject);
+  }
+}
+
+void DeviceMonitorMac::AudioDeviceChangedCallback(void *context,
+                                                  io_iterator_t devices) {
+  io_object_t thisObject;
+  while ((thisObject = IOIteratorNext(devices))) {

[Avi (use Gerrit), 2012/08/03 19:41:23]

Ditto.

[no longer working on chromium, 2012/08/06 09:43:12]

Done.

+    if (context) {
+      InstanceFromContext(context)->NotifyDeviceChanged(
+          base::SystemMonitor::DEVTYPE_AUDIO_CAPTURE);
+    }
+    IOObjectRelease(thisObject);
+  }
+}
+
+void DeviceMonitorMac::NotifyDeviceChanged(
+    base::SystemMonitor::DeviceType type) {
+  base::SystemMonitor::Get()->ProcessDevicesChanged(type);
+}
+
+
+DeviceMonitorMac::~DeviceMonitorMac() {}
+
+}  // namespace content