Add Media device notification to SystemMonitor and Mac impl

content/browser/mac/media_device_notifications.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/mac/media_device_notifications.h"
+
+#include <Carbon/Carbon.h>
+#include <CoreFoundation/CoreFoundation.h>
+
+#include "base/file_path.h"
+#include "base/mac/foundation_util.h"
+#include "base/mac/scoped_cftyperef.h"
+#include "base/sys_string_conversions.h"
+#include "base/system_monitor/system_monitor.h"
+
+namespace content {
+
+namespace {
+
+const CFStringRef kICAUserAssignedDeviceNameKey =
+    base::mac::NSToCFCast(@"ICAUserAssignedDeviceNameKey");

[Avi (use Gerrit), 2012/02/28 01:26:46]

CFSTR() here and the next two lines.

[vandebo (ex-Chrome), 2012/02/28 18:35:05]

Done.

+const CFStringRef kICDeviceNameKey = base::mac::NSToCFCast(@"ifil");
+const CFStringRef kICDeviceBSDNameKey = base::mac::NSToCFCast(@"bsdName");
+
+CFStringRef CopyMountPointFromBSDName(const char* bsd_name) {

[Avi (use Gerrit), 2012/02/28 01:26:46]

It's weird that this doesn't take a CF argument but returns one. Have it do the
base::SysCFStringRefToUTF8(device).c_str() conversion inside here and spare the
caller.

And yes, this is _exactly_ what I was looking for; thanks!

[vandebo (ex-Chrome), 2012/02/28 18:35:05]

Done.

+  base::mac::ScopedCFTypeRef<DASessionRef> session(
+      DASessionCreate(kCFAllocatorDefault));
+  if (!session.get())
+    return NULL;
+
+  base::mac::ScopedCFTypeRef<DADiskRef> disk(
+      DADiskCreateFromBSDName(kCFAllocatorDefault, session.get(), bsd_name));
+  if (!disk.get())
+    return NULL;
+
+  base::mac::ScopedCFTypeRef<CFDictionaryRef> description(
+      DADiskCopyDescription(disk));
+  if (!description.get())
+    return NULL;
+
+  CFURLRef mount_point = base::mac::GetValueFromDictionary<CFURLRef>(
+      description, kDADiskDescriptionVolumePathKey);
+  if (!mount_point)
+    return NULL;
+
+  return CFURLCopyFileSystemPath(mount_point, kCFURLComponentPath);

[Avi (use Gerrit), 2012/02/28 01:26:46]

You mean kCFURLPOSIXPathStyle. (kCFURLComponentPath is a CFURLComponentType, not
a CFURLPathStyle.)

[vandebo (ex-Chrome), 2012/02/28 18:35:05]

Done.

+}
+
+bool GetDeviceInfo(unsigned long device_number, std::string* name,
+                   FilePath* location) {
+  ICACopyObjectPropertyDictionaryPB properties_request;
+  properties_request.object = device_number;
+  CFDictionaryRef device_properties;
+  properties_request.theDict = &device_properties;
+  OSErr ret = ICACopyObjectPropertyDictionary(&properties_request, NULL);
+  base::mac::ScopedCFTypeRef<CFDictionaryRef> scoped_device_properties(
+      device_properties);
+  CHECK_EQ(ret, noErr);

[Avi (use Gerrit), 2012/02/28 01:26:46]

Everywhere else, if a null is returned you return false from this function. Why
does this one deserve the severity of CHECK? (Also, move to the line after the
call to ICACopyObjectPropertyDictionary.)

[vandebo (ex-Chrome), 2012/02/28 18:35:05]

Done.

+
+  CFStringRef device_name = base::mac::GetValueFromDictionary<CFStringRef>(
+      device_properties, kICAUserAssignedDeviceNameKey);
+  if (device_name == NULL) {
+    device_name = base::mac::GetValueFromDictionary<CFStringRef>(
+        device_properties, kICDeviceNameKey);
+  }
+  if (device_name == NULL)
+    return false;
+  *name = base::SysCFStringRefToUTF8(device_name);
+
+  // TODO(vandebo) Support all media device, for now we only support mass
+  // storage media devices.
+  CFStringRef device = base::mac::GetValueFromDictionary<CFStringRef>(
+      device_properties, kICDeviceBSDNameKey);
+  if (device == NULL)
+    return false;
+  base::mac::ScopedCFTypeRef<CFStringRef> path(
+      CopyMountPointFromBSDName(base::SysCFStringRefToUTF8(device).c_str()));
+  if (path.get() == NULL)
+    return false;
+
+  *location = FilePath(base::SysCFStringRefToUTF8(path).c_str());
+
+  return true;
+}
+
+void MediaDeviceNotificationCallback(CFStringRef notification_type,
+                                     CFDictionaryRef notification_dictionary) {
+  bool attach = false;
+  if (CFEqual(notification_type, kICANotificationTypeDeviceAdded)) {
+    attach = true;
+  } else if (CFEqual(notification_type, kICANotificationTypeDeviceRemoved)) {
+    return;

[Avi (use Gerrit), 2012/02/28 01:26:46]

A little confused; why the return here? If you don't want to deal with this
notification type, why register for it?

[vandebo (ex-Chrome), 2012/02/28 18:35:05]

A conversion bug, from CFStringCompare.  I would have caught it anyway when I
had a chance to test today.

+  }
+
+  base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
+
+  CFNumberRef device_number_object =
+      base::mac::GetValueFromDictionary<CFNumberRef>(
+          notification_dictionary, kICANotificationDeviceICAObjectKey);
+  unsigned long device_number =
+      [base::mac::CFToNSCast(device_number_object) unsignedLongValue];
+  if (attach) {
+    std::string device_name;
+    FilePath location;
+    if (GetDeviceInfo(device_number, &device_name, &location)) {
+      system_monitor->ProcessMediaDeviceAttached(device_number, device_name,
+                                                 location);
+    }
+  } else {
+    system_monitor->ProcessMediaDeviceDetached(device_number);
+  }
+}
+
+}  // namespace
+
+void StartMediaDeviceNotifications() {
+  NSArray* events_of_interest = [NSArray arrayWithObjects:
+                                 (id)kICANotificationTypeDeviceAdded,
+                                 (id)kICANotificationTypeDeviceRemoved,
+                                 NULL];

[Avi (use Gerrit), 2012/02/28 01:26:46]

nil (not NULL) is used when referring to an ObjC object.

[vandebo (ex-Chrome), 2012/02/28 18:35:05]

Done.

+
+  ICARegisterForEventNotificationPB notification_request;
+  notification_request.objectOfInterest = 0;  // Zero means all objects
+  notification_request.eventsOfInterest =
+      base::mac::NSToCFCast(events_of_interest);
+  notification_request.notificationProc = &MediaDeviceNotificationCallback;
+  notification_request.options = NULL;
+  OSErr err = ICARegisterForEventNotification(&notification_request, NULL);
+  CHECK_EQ(err, noErr);
+}
+
+}  // namespace content