[Mac] Make app shims load the same framework version as the running Chrome process.

chrome/app/app_mode_loader_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.
 
 // On Mac, shortcuts can't have command-line arguments. Instead, produce small
 // app bundles which locate the Chromium framework and load it, passing the
 // appropriate data. This is the code for such an app bundle. It should be kept
 // minimal and do as little work as possible (with as much work done on
 // framework side as possible).
 
@@ skipping 25 matching lines @@
   using base::mac::CFToNSCast;
   using base::mac::CFCastStrict;
   using base::mac::NSToCFCast;
 
   base::mac::ScopedNSAutoreleasePool scoped_pool;
 
   // Get the current main bundle, i.e., that of the app loader that's running.
   NSBundle* app_bundle = [NSBundle mainBundle];
   CHECK(app_bundle) << "couldn't get loader bundle";
 
+  // Read information about the this app shortcut from the Info.plist.
+  // Don't check for null-ness on optional items.
+  NSDictionary* info_plist = [app_bundle infoDictionary];
+  CHECK(info_plist) << "couldn't get loader Info.plist";
+
+  info->app_mode_id = SysNSStringToUTF8(
+      [info_plist objectForKey:app_mode::kCrAppModeShortcutIDKey]);
+  CHECK(info->app_mode_id.size()) << "couldn't get app shortcut ID";
+
+  info->app_mode_name = SysNSStringToUTF16(
+      [info_plist objectForKey:app_mode::kCrAppModeShortcutNameKey]);
+
+  info->app_mode_url = SysNSStringToUTF8(
+      [info_plist objectForKey:app_mode::kCrAppModeShortcutURLKey]);
+
+  info->user_data_dir = base::mac::NSStringToFilePath(
+      [info_plist objectForKey:app_mode::kCrAppModeUserDataDirKey]);
+
+  info->profile_dir = base::mac::NSStringToFilePath(
+      [info_plist objectForKey:app_mode::kCrAppModeProfileDirKey]);
+
   // ** 1: Get path to outer Chrome bundle.
   // Get the bundle ID of the browser that created this app bundle.
   NSString* cr_bundle_id = base::mac::ObjCCast<NSString>(
       [app_bundle objectForInfoDictionaryKey:app_mode::kBrowserBundleIDKey]);
   CHECK(cr_bundle_id) << "couldn't get browser bundle ID";
 
   // First check if Chrome exists at the last known location.
   base::FilePath cr_bundle_path;
   NSString* cr_bundle_path_ns =
       [CFToNSCast(CFCastStrict<CFStringRef>(CFPreferencesCopyAppValue(
           NSToCFCast(app_mode::kLastRunAppBundlePathPrefsKey),
           NSToCFCast(cr_bundle_id)))) autorelease];
   cr_bundle_path = base::mac::NSStringToFilePath(cr_bundle_path_ns);
   bool found_bundle =
       !cr_bundle_path.empty() && base::DirectoryExists(cr_bundle_path);
 
   if (!found_bundle) {
     // If no such bundle path exists, try to search by bundle ID.
     if (!app_mode::FindBundleById(cr_bundle_id, &cr_bundle_path)) {
       // TODO(jeremy): Display UI to allow user to manually locate the Chrome
       // bundle.
       LOG(FATAL) << "Failed to locate bundle by identifier";
     }
   }
 
+  // The user_data_dir for shims actually contains the app_data_path.

[tapted, 2014/08/26 07:12:47]

for consistency: // ** 2: Read the running Chrome version.

[jackhou1, 2014/08/26 08:15:14]

Done.

+  // I.e. <user_data_dir>/<profile_dir>/Web Applications/_crx_extensionid/
+  base::FilePath user_data_dir =

[tapted, 2014/08/26 07:12:47]

Can you keep the ChromeAppModeInfo populating together if you do something like

  base::FilePath app_data_dir = base::mac::NSStringToFilePath([app_bundle
      objectForInfoDictionaryKey:app_mode::kCrAppModeUserDataDirKey]);
  base::FilePath user_data_dir = app_data_dir.DirName().DirName().DirName();

(i.e. what's done above for cr_bundle_id)

[jackhou1, 2014/08/26 08:15:14]

Done.

+      info->user_data_dir.DirName().DirName().DirName();
+  CHECK(!user_data_dir.empty());
+
+  // Check if there is a version file written by Chrome. If so, use it to load
+  // the correct version of the framework. If not, app_mode::GetChromeBundleInfo
+  // will just load the latest version.
+  base::FilePath cr_version_str;
+  base::ReadSymbolicLink(
+      user_data_dir.Append(app_mode::kAppShimVersionSymlinkName),
+      &cr_version_str);
+
   // ** 2: Read information from the Chrome bundle.
   base::FilePath executable_path;
-  base::string16 raw_version_str;
   base::FilePath version_path;
   base::FilePath framework_shlib_path;
   if (!app_mode::GetChromeBundleInfo(cr_bundle_path,
+                                     cr_version_str.value(),

[tapted, 2014/08/26 07:12:47]

I think we can only pass this in when we know for sure that Chrome is running. 

Otherwise, e.g. if Chrome crashes, the call to
`base::mac::OpenApplicationWithPath(base::mac::OuterBundlePath(), ...` in
ChromeAppModeStart could end up loading a newer version of Chrome

[jackhou1, 2014/08/26 08:15:14]

Hmm... I think we can read the SingletonLock to confirm the pid is still
running. If not, load the newer version. WDYT?

[tapted, 2014/08/26 08:43:47]

yeah I think that should be OK - it's only a remote possibility to begin with,
so worrying about something else grabbing the same pid in the meantime is super
unlikely.  You could also use `[NSRunningApplication
runningApplicationsWithBundleIdentifier:bundle_id]` but I think it can have
multiple things if someone runs Chrome on Mac with --user-data-dir (or on a
multi-user machine).

[jackhou1, 2014/08/27 03:04:52]

Reading SingletonLock doesn't seem to work, maybe we can't read it while Chrome
has a lock on it. In any case, it might be flaky if the singleton code changes.
Changed this to use NSRunningApplication.

                                      &executable_path,
-                                     &raw_version_str,
                                      &version_path,
                                      &framework_shlib_path)) {
     LOG(FATAL) << "Couldn't ready Chrome bundle info";
   }
   base::FilePath app_mode_bundle_path =
       base::mac::NSStringToFilePath([app_bundle bundlePath]);
 
   // ** 3: Fill in ChromeAppModeInfo.
   info->chrome_outer_bundle_path = cr_bundle_path;
   info->chrome_versioned_path = version_path;
   info->app_mode_bundle_path = app_mode_bundle_path;
 
-  // Read information about the this app shortcut from the Info.plist.
-  // Don't check for null-ness on optional items.
-  NSDictionary* info_plist = [app_bundle infoDictionary];
-  CHECK(info_plist) << "couldn't get loader Info.plist";
-
-  info->app_mode_id = SysNSStringToUTF8(
-      [info_plist objectForKey:app_mode::kCrAppModeShortcutIDKey]);
-  CHECK(info->app_mode_id.size()) << "couldn't get app shortcut ID";
-
-  info->app_mode_name = SysNSStringToUTF16(
-      [info_plist objectForKey:app_mode::kCrAppModeShortcutNameKey]);
-
-  info->app_mode_url = SysNSStringToUTF8(
-      [info_plist objectForKey:app_mode::kCrAppModeShortcutURLKey]);
-
-  info->user_data_dir = base::mac::NSStringToFilePath(
-      [info_plist objectForKey:app_mode::kCrAppModeUserDataDirKey]);
-
-  info->profile_dir = base::mac::NSStringToFilePath(
-      [info_plist objectForKey:app_mode::kCrAppModeProfileDirKey]);
-
   // Open the framework.
   StartFun ChromeAppModeStart = NULL;
   void* cr_dylib = dlopen(framework_shlib_path.value().c_str(), RTLD_LAZY);
   if (cr_dylib) {
     // Find the entry point.
     ChromeAppModeStart = (StartFun)dlsym(cr_dylib, "ChromeAppModeStart");
     if (!ChromeAppModeStart)
       LOG(ERROR) << "Couldn't get entry point: " << dlerror();
   } else {
     LOG(ERROR) << "Couldn't load framework: " << dlerror();
@@ skipping 51 matching lines @@
   // Hard coded info parameters.
   info.major_version = app_mode::kCurrentChromeAppModeInfoMajorVersion;
   info.minor_version = app_mode::kCurrentChromeAppModeInfoMinorVersion;
   info.argc = argc;
   info.argv = argv;
 
   // Exit instead of returning to avoid the the removal of |main()| from stack
   // backtraces under tail call optimization.
   exit(LoadFrameworkAndStart(&info));
 }