Detect if user closes the pref-pane without disabling Chromoting

remoting/host/me2me_preference_pane.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.
 
 #import "remoting/host/me2me_preference_pane.h"
 
 #import <Cocoa/Cocoa.h>
 #include <CommonCrypto/CommonHMAC.h>
 #include <errno.h>
 #include <launch.h>
@@ skipping 17 matching lines @@
 namespace {
 // The name of the Remoting Host service that is registered with launchd.
 #define kServiceName "org.chromium.chromoting"
 
 // Use separate named notifications for success and failure because sandboxed
 // components can't include a dictionary when sending distributed notifications.
 // The preferences panel is not yet sandboxed, but err on the side of caution.
 #define kUpdateSucceededNotificationName kServiceName ".update_succeeded"
 #define kUpdateFailedNotificationName kServiceName ".update_failed"
 
+// This notification (or the UpdateFailed notification) is sent whenever the
+// pref-pane is deselected.  This is analogous to the user canceling the
+// confirm-PIN dialog (or UAC prompt) on Windows.
+// If the plugin is expecting an action to occur (such as the user disabling
+// the Host service), it should treat this as a signal to stop waiting, and
+// assume the action has been canceled by the user.
+// Otherwise, the plugin should ignore this notification.  The pref-pane does
+// not know whether it was launched by the plugin or by the user (in the case
+// of disabling remote connections), so it has to send this notification
+// regardless.
+#define kUserCanceledNotificationName kServiceName ".user_canceled"

[Jamie, 2012/06/15 22:34:56]

Can we call this update_canceled for consistency with the other two?

+
 #define kConfigDir "/Library/PrivilegedHelperTools/"
 
 // This helper script is executed as root.  It is passed a command-line option
 // (--enable or --disable), which causes it to create or remove a file that
 // informs the host's launch script of whether the host is enabled or disabled.
 const char kHelperTool[] = kConfigDir kServiceName ".me2me.sh";
 
 bool GetTemporaryConfigFilePath(std::string* path) {
   NSString* filename = NSTemporaryDirectory();
   if (filename == nil)
@@ skipping 274 matching lines @@
 - (void)willUnselect {
   NSDistributedNotificationCenter* center =
       [NSDistributedNotificationCenter defaultCenter];
   [center removeObserver:self];
 
   [service_status_timer_ invalidate];
   [service_status_timer_ release];
   service_status_timer_ = nil;
   if (have_new_config_)
     [self notifyPlugin:kUpdateFailedNotificationName];
+  else
+    [self notifyPlugin:kUserCanceledNotificationName];

[Jamie, 2012/06/15 22:34:56]

This feels inconsistent. Why send a failed notification for the "start/change
PIN" pane, but a canceled notification for the "stop" pane?

 }
 
 - (void)applyConfiguration:(id)sender
                        pin:(NSString*)pin {
   if (!have_new_config_) {
     // It shouldn't be possible to hit the button if there is no config to
     // apply, but check anyway just in case it happens somehow.
     return;
   }
 
@@ skipping 404 matching lines @@
     // spinning state until System Preferences eventually gets restarted and
     // the user visits this pane again.
     std::string file;
     if (!GetTemporaryConfigFilePath(&file)) {
       // There's no point in alerting the user here.  The same error would
       // happen when the pane is eventually restarted, so the user would be
       // alerted at that time.
       NSLog(@"Failed to get path of configuration data.");
       return;
     }
-    if (access(file.c_str(), F_OK) != 0)
-      return;
-
-    remove(file.c_str());
-    [self notifyPlugin:kUpdateFailedNotificationName];
+    if (access(file.c_str(), F_OK) != 0) {
+      [self notifyPlugin:kUserCanceledNotificationName];

[Jamie, 2012/06/15 22:34:56]

Under what circumstances can this happen? Would it make sense to send an error
notification instead?

+    } else {
+      remove(file.c_str());
+      [self notifyPlugin:kUpdateFailedNotificationName];
+    }
   }
 }
 
 - (void)restartSystemPreferences {
   NSTask* task = [[NSTask alloc] init];
   NSArray* arguments = [NSArray arrayWithObjects:@"--relaunch-prefpane", nil];
   [task setLaunchPath:[NSString stringWithUTF8String:kHelperTool]];
   [task setArguments:arguments];
   [task setStandardInput:[NSPipe pipe]];
   [task launch];
   [task release];
   [NSApp terminate:nil];
 }
 
 @end