Add a self-destruct mechanism to user-level Chrome Frame when it detects that system-level Chrome...

chrome_frame/chrome_frame_helper_main.cc

Index: chrome_frame/chrome_frame_helper_main.cc
===================================================================
--- chrome_frame/chrome_frame_helper_main.cc	(revision 86605)
+++ chrome_frame/chrome_frame_helper_main.cc	(working copy)
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 //
@@ -13,16 +13,38 @@
 //
 
 #include <crtdbg.h>
+#include <objbase.h>
 #include <windows.h>
 
+#include "chrome_frame/chrome_frame_helper_util.h"
 #include "chrome_frame/crash_server_init.h"
+#include "chrome_frame/registry_watcher.h"
 
+namespace {
 // Window class and window names.

[grt (UTC plus 2), 2011/05/26 17:08:58]

nit: newline before this

[robertshield, 2011/05/27 03:34:59]

Done.

 const wchar_t kChromeFrameHelperWindowClassName[] =
     L"ChromeFrameHelperWindowClass";
 const wchar_t kChromeFrameHelperWindowName[] =
     L"ChromeFrameHelperWindowName";
 
+const wchar_t kChromeFrameClientStateKey[] =
+    L"Software\\Google\\Update\\ClientState\\"
+    L"{8BA986DA-5100-405E-AA35-86F34A02ACBF}";
+const wchar_t kChromeFrameUninstallCmdExeValue[] = L"UninstallString";
+const wchar_t kChromeFrameUninstallCmdArgsValue[] = L"UninstallArguments";
+
+const wchar_t kBHORegistrationPath[] =
+    L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer"
+    L"\\Browser Helper Objects";
+
+const wchar_t kStartupArg[] = L"--startup";
+const wchar_t kForceUninstall[] = L"--force-uninstall";
+
+HWND g_hwnd = NULL;
+const UINT kRegistryWatcherChangeMessage = WM_USER + 42;
+
+}  // namespace
+
 // Small helper class that assists in loading the DLL that contains code
 // to register our event hook callback. Automatically removes the hook and
 // unloads the DLL on destruction.
@@ -108,6 +130,8 @@
     case WM_CREATE:
       CloseAllHelperWindowsApartFrom(hwnd);
       break;
+    case kRegistryWatcherChangeMessage:
+      // A system level Chrome appeared. Fall through:
     case WM_DESTROY:
       PostQuitMessage(0);
       break;
@@ -133,21 +157,107 @@
   return hwnd;
 }
 
+
+// This method runs the user-level Chrome Frame uninstall command. This is
+// intended to allow it to delegate to an existing system-level install.
+bool UninstallUserLevelChromeFrame() {
+  bool success = false;
+  HKEY reg_handle = NULL;
+  wchar_t reg_path_buffer[MAX_PATH] = {0};
+  LONG result = RegOpenKeyEx(HKEY_CURRENT_USER,
+                             kChromeFrameClientStateKey,
+                             0,
+                             KEY_QUERY_VALUE,
+                             &reg_handle);
+  if (result == ERROR_SUCCESS) {
+    wchar_t exe_buffer[MAX_PATH] = {0};
+    wchar_t args_buffer[MAX_PATH] = {0};
+    LONG exe_result = ReadValue(reg_handle,
+                                kChromeFrameUninstallCmdExeValue,
+                                MAX_PATH,
+                                exe_buffer);
+    LONG args_result = ReadValue(reg_handle,
+                                 kChromeFrameUninstallCmdArgsValue,
+                                 MAX_PATH,
+                                 args_buffer);
+    RegCloseKey(reg_handle);
+    reg_handle = NULL;
+
+    if (exe_result == ERROR_SUCCESS && args_result == ERROR_SUCCESS) {
+      STARTUPINFO startup_info = {0};
+      startup_info.cb = sizeof(startup_info);
+      startup_info.dwFlags = STARTF_USESHOWWINDOW;
+      startup_info.wShowWindow = SW_SHOW;
+      PROCESS_INFORMATION process_info = {0};
+
+      // Quote the command string in the args.
+      wchar_t argument_string[MAX_PATH * 3] = {0};
+      _snwprintf(argument_string,

[grt (UTC plus 2), 2011/05/26 17:08:58]

int argument_string_len = _snwprintf(...);
if (argument_string_len > 0 && CreateProcess(...)) {...

[robertshield, 2011/05/27 03:34:59]

Done.

+                 MAX_PATH * 3,

[grt (UTC plus 2), 2011/05/26 17:08:58]

_countof(argument_string) would be more safe, no? (include <stdlib.h> if so)

[robertshield, 2011/05/27 03:34:59]

_countof() - 1, just to ensure that the string remains null-terminated.

[grt (UTC plus 2), 2011/05/27 14:07:58]

Good call.

+                 L"\"%s\" %s %s",
+                 exe_buffer,
+                 args_buffer,
+                 kForceUninstall);
+
+      if (CreateProcess(exe_buffer, argument_string,
+                        NULL, NULL, FALSE, 0, NULL, NULL,
+                        &startup_info, &process_info)) {
+        // Close handles.
+        CloseHandle(process_info.hThread);
+        CloseHandle(process_info.hProcess);
+        success = true;
+      }
+    }
+  }
+
+  return success;
+}
+
+void CALLBACK WaitCallback(void* param, BOOLEAN wait_fired) {
+  RegistryWatcher* watcher = reinterpret_cast<RegistryWatcher*>(param);
+  if (watcher->stopping())
+    return;
+
+  // Check if the Chrome Frame BHO is now in the list of registered BHOs:
+  if (IsBHOLoadingPolicyRegistered()) {
+    // Post message.

[grt (UTC plus 2), 2011/05/26 17:08:58]

This comment adds nothing.  Please either make it meaningful or remove it.

[robertshield, 2011/05/27 03:34:59]

Done.

+    PostMessage(g_hwnd, kRegistryWatcherChangeMessage, 0, 0);
+  }
+}
+
 int APIENTRY wWinMain(HINSTANCE hinstance, HINSTANCE, wchar_t*, int show_cmd) {
   const wchar_t* cmd_line = ::GetCommandLine();
   google_breakpad::scoped_ptr<google_breakpad::ExceptionHandler> breakpad(
       InitializeCrashReporting(cmd_line));
 
+  if (IsSystemLevelChromeFrameInstalled()) {
+    // If we're running at startup, check for system-level Chrome Frame
+    // installations. If we have one, time
+    // to bail, also schedule user-level CF to be uninstalled at next logon.
+    const wchar_t* cmd_line = ::GetCommandLine();
+    if (cmd_line && wcsstr(cmd_line, kStartupArg) != NULL) {
+      bool uninstalled = UninstallUserLevelChromeFrame();
+      _ASSERTE(uninstalled);
+    }
+    return 0;
+  }
+
   // Create a window with a known class and title just to listen for WM_CLOSE
   // messages that will shut us down.
-  HWND hwnd = RegisterAndCreateWindow(hinstance);
-  _ASSERTE(hwnd);
+  g_hwnd = RegisterAndCreateWindow(hinstance);
+  _ASSERTE(IsWindow(g_hwnd));
 
   // Load the hook dll, and set the event hooks.
   HookDllLoader loader;
   bool loaded = loader.Load();
   _ASSERTE(loaded);
 
+  // Start up the registry watcher
+  RegistryWatcher registry_watcher(HKEY_LOCAL_MACHINE, kBHORegistrationPath,
+                                   WaitCallback);
+  bool watching = registry_watcher.StartWatching();
+  _ASSERTE(watching);
+
   if (loaded) {
     MSG msg;
     BOOL ret;