Restart Mac pref-pane if version mismatch detected

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 <launch.h>
 #import <PreferencePanes/PreferencePanes.h>
@@ skipping 258 matching lines @@
 - (void)updateServiceStatus {
   pid_t job_pid = base::mac::PIDForJob(kServiceName);
   is_service_running_ = (job_pid > 0);
 }
 
 - (void)updateAuthorizationStatus {
   is_pane_unlocked_ = [authorization_view_ updateStatus:authorization_view_];
 }
 
 - (void)readNewConfig {
+  [self restartPanelIfDifferentVersionInstalled];
+
   std::string file;
   if (!GetTemporaryConfigFilePath(&file)) {
     LOG(ERROR) << "Failed to get path of configuration data.";
     [self showError];
     return;
   }
   if (access(file.c_str(), F_OK) != 0)
     return;
 
   scoped_ptr<remoting::JsonHostConfig> new_config_(
@@ skipping 222 matching lines @@
 
 - (void)notifyPlugin:(const char*)message {
   NSDistributedNotificationCenter* center =
       [NSDistributedNotificationCenter defaultCenter];
   NSString* name = [NSString stringWithUTF8String:message];
   [center postNotificationName:name
                         object:nil
                       userInfo:nil];
 }
 
+- (void)restartPanelIfDifferentVersionInstalled {
+  NSBundle* this_bundle = [NSBundle bundleForClass:[self class]];
+  NSDictionary* this_plist = [this_bundle infoDictionary];
+  NSString* this_version = [this_plist objectForKey:@"CFBundleVersion"];
+
+  NSString* bundle_path = [this_bundle bundlePath];
+  NSString* plist_path =
+      [bundle_path stringByAppendingString:@"/Contents/Info.plist"];
+  NSDictionary* disk_plist =
+      [NSDictionary dictionaryWithContentsOfFile:plist_path];
+  NSString* disk_version = [disk_plist objectForKey:@"CFBundleVersion"];
+
+  if (disk_version == nil) {
+    LOG(ERROR) << "Failed to get installed version information";
+    [self showError];
+    return;
+  }
+
+  if (![this_version isEqualToString:disk_version]) {

[Jamie, 2012/05/23 01:17:17]

Optional: My ObjC knowledge is not enough to know whether or not this is a
genuine concern, but it occurs to me that you're using two different methods to
obtain the version string, and assuming they're going to return the same thing
in the case that nothing has changed. On the face of it, this seems like a
reasonable assumption, but you could avoid it if you use the on-disk method to
read the version number at start-up and cache it.

[Lambros, 2012/05/24 00:54:50]

I'm not sure which method is better, so I'll leave it for now.

+    // Terminate and relaunch System Preferences.
+
+    // TODO(lambroslambrou): Improve this when System Preferences supports
+    // dynamic reloading of pref-panes.
+    NSTask* task = [[NSTask alloc] init];
+    NSArray* arguments = [NSArray arrayWithObjects:@"--launch-prefpane", nil];
+    [task setLaunchPath:[NSString stringWithUTF8String:kHelperTool]];
+    [task setArguments:arguments];
+    [task setStandardInput:[NSPipe pipe]];
+    [task launch];
+    [task release];
+    [NSApp terminate:nil];

[dcaiafa, 2012/05/23 17:16:19]

I don't think terminate: is like exit(). The code following restartPanel will
still run. Is this intended? 

[Lambros, 2012/05/24 00:54:50]

Good catch!  The following code would've loaded and deleted the config file,
before the pref-pane got restarted - not what we want!
I've fixed this by having this method return BOOL, and having the caller abort
without loading the config.

+  }
+}
+
 @end