gears/base/ie/detect_version_collision.cc

   1 // Copyright 2007, Google Inc.
   2 //
   3 // Redistribution and use in source and binary forms, with or without
   4 // modification, are permitted provided that the following conditions are met:
   5 //
   6 //  1. Redistributions of source code must retain the above copyright notice,
   7 //     this list of conditions and the following disclaimer.
   8 //  2. Redistributions in binary form must reproduce the above copyright notice,
   9 //     this list of conditions and the following disclaimer in the documentation
  10 //     and/or other materials provided with the distribution.
  11 //  3. Neither the name of Google Inc. nor the names of its contributors may be
  12 //     used to endorse or promote products derived from this software without
  13 //     specific prior written permission.
  14 //
  15 // THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  16 // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  17 // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
  18 // EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  19 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  20 // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  21 // OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  22 // WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  23 // OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  24 // ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25
  26 #include <assert.h>
  27 #include <atlbase.h>
  28 #include <atlsync.h>
  29 #include <windows.h>
  30 #include "common/genfiles/product_constants.h"  // from OUTDIR
  31 #include "gears/base/ie/detect_version_collision.h"
  32
  33 // We run our detection code once at startup
  34 static bool OneTimeDetectVersionCollision();
  35 static bool detected_collision = OneTimeDetectVersionCollision();
  36
  37 bool DetectedVersionCollision() {
  38   return detected_collision;
  39 }
  40
  41 // We use two named mutex objects to determine if another version of
  42 // Gears is running.  The first indicates at least one instance of some
  43 // version of Gears is running. The second indicates at least one instance
  44 // of our version of Gears is running. The embedded GUID in the mutex names
  45 // should not be changed across different versions.
  46 // TODO(michaeln): Ideally, these should be per user kernel objects rather
  47 // than per local session to detect when the same user is running Gears in
  48 // another windows session. See //depot/googleclient/ci/common/synchronized.cpp
  49 // for some clues.
  50 static CMutex running_mutex;
  51 static CMutex our_version_running_mutex;
  52
  53 static const wchar_t *kMutexName =
  54     L"IsRunning{685E0F7D-005A-40a0-B9F8-168FBA824248}";
  55
  56 static const wchar_t *kOurVersionMutexName =
  57     L"IsRunning{685E0F7D-005A-40a0-B9F8-168FBA824248}-" PRODUCT_VERSION_STRING;
  58
  59 // Returns true if we detect that a different version of Gears is running.
  60 // If no collision is detected, leaves mutex handles open to indicate that
  61 // our version is running.  If a collision is detected, this instance of Gears
  62 // will be crippled, so we close all mutex handles so others don't see this
  63 // instance as 'running'. Should only be called once.
  64 static bool OneTimeDetectVersionCollision() {
  65   // Detect if an instance of any version is running
  66   if (!running_mutex.Create(NULL, FALSE, kMutexName)) {
  67     assert(false);
  68     return true;
  69   }
  70   bool already_running = (GetLastError() == ERROR_ALREADY_EXISTS);
  71
  72   // Detect if another instance of our version is running
  73   if (!our_version_running_mutex.Create(NULL, FALSE, kOurVersionMutexName)) {
  74     assert(false);
  75     running_mutex.Close();
  76     return true;
  77   }
  78   bool our_version_already_running = (GetLastError() == ERROR_ALREADY_EXISTS);
  79
  80   if (!already_running) {
  81     // No collision, we are the first instance to run
  82     assert(!our_version_already_running);
  83     return false;
  84   } else if (our_version_already_running) {
  85     // No collision, other instances of our version are running
  86     return false;
  87   } else {
  88     // A collision with a different version!
  89     our_version_running_mutex.Close();
  90     running_mutex.Close();
  91     return true;
  92   }
  93 }
  94
  95 // Low tech UI to notify the user
  96 static bool alerted_user = false;
  97 const wchar_t *kVersionCollisionErrorMessage =
  98     L"A " PRODUCT_FRIENDLY_NAME L" update has been downloaded.\n\n"
  99     L"Please close all browser windows to complete the upgrade process.\n";
 100
 101 void MaybeNotifyUserOfVersionCollision() {
 102   assert(detected_collision);
 103   if (!alerted_user) {
 104     NotifyUserOfVersionCollision();
 105   }
 106 }
 107
 108 void NotifyUserOfVersionCollision() {
 109   assert(detected_collision);
 110   alerted_user = true;
 111   MessageBox(NULL, kVersionCollisionErrorMessage,
 112              L"Please restart your browser", MB_OK);
 113 }