toolkit/xre/nsUpdateMutex.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "nsUpdateMutex.h"
   8
   9 #include "mozilla/DebugOnly.h"
  10 #include "mozilla/ScopeExit.h"
  11 #include "mozilla/StaticMutex.h"
  12 #include "nsIFile.h"
  13 #include "nsProfileLock.h"
  14 #include "nsXULAppAPI.h"
  15
  16 mozilla::StaticMutex UpdateMutexImpl::sInProcessMutex;
  17
  18 bool UpdateMutexImpl::TryLock() {
  19   if (!sInProcessMutex.TryLock()) {
  20     return false;
  21   }
  22
  23   bool success = [&crossProcessLock = mCrossProcessLock]() {
  24     nsCOMPtr<nsIFile> updRoot;
  25     nsresult nsrv =
  26         NS_GetSpecialDirectory(XRE_UPDATE_ROOT_DIR, getter_AddRefs(updRoot));
  27     if (NS_FAILED(nsrv)) {
  28       return false;
  29     }
  30
  31     nsrv = updRoot->Create(nsIFile::DIRECTORY_TYPE, 0755);
  32     if (NS_FAILED(nsrv) && nsrv != NS_ERROR_FILE_ALREADY_EXISTS) {
  33       return false;
  34     }
  35
  36     return NS_SUCCEEDED(crossProcessLock.Lock(updRoot, nullptr));
  37   }();
  38
  39   if (!success) {
  40     sInProcessMutex.Unlock();
  41   }
  42
  43   return success;
  44 }
  45
  46 void UpdateMutexImpl::Unlock() {
  47   sInProcessMutex.AssertCurrentThreadOwns();
  48
  49   mozilla::DebugOnly<nsresult> nsrv = mCrossProcessLock.Unlock();
  50 #ifdef DEBUG
  51   if (!NS_SUCCEEDED(nsrv)) {
  52     MOZ_CRASH_UNSAFE_PRINTF(
  53         "failed to unlock the update mutex's nsProfileLock -- got 0x%08x",
  54         static_cast<uint32_t>(nsrv.inspect()));
  55   }
  56 #endif
  57
  58   sInProcessMutex.Unlock();
  59 }
  60
  61 NS_IMPL_ISUPPORTS(nsUpdateMutex, nsIUpdateMutex)
  62
  63 NS_IMETHODIMP nsUpdateMutex::IsLocked(bool* aResult) {
  64   *aResult = mIsLocked;
  65   return NS_OK;
  66 }
  67
  68 NS_IMETHODIMP nsUpdateMutex::TryLock(bool* aResult) {
  69   if (!mIsLocked) {
  70     mIsLocked = mUpdateMutexImpl.TryLock();
  71   }
  72   *aResult = mIsLocked;
  73   return NS_OK;
  74 }
  75
  76 NS_IMETHODIMP nsUpdateMutex::Unlock() MOZ_NO_THREAD_SAFETY_ANALYSIS {
  77   // Thread safety analysis cannot make sense out of a conditional release
  78   if (mIsLocked) {
  79     mUpdateMutexImpl.Unlock();
  80     mIsLocked = false;
  81   }
  82   return NS_OK;
  83 }