1 files changed, 130 insertions, 0 deletions
diff --git a/toolkit/xre/nsUpdateSyncManager.cpp b/toolkit/xre/nsUpdateSyncManager.cpp
new file mode 100644
index 0000000000..37ba83f4d7
--- /dev/null
+++ b/toolkit/xre/nsUpdateSyncManager.cpp
@@ -0,0 +1,130 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsUpdateSyncManager.h"
+
+#include "mozilla/Unused.h"
+#include "mozilla/Services.h"
+#include "nsComponentManagerUtils.h"
+#include "nsCRT.h"
+#include "nsIFile.h"
+#include "nsIObserverService.h"
+#include "nsIProperties.h"
+#include "nsString.h"
+#include "nsXULAppAPI.h"
+
+// The lock code generates a path that already includes the vendor name,
+// so this only needs to name the specific lock.
+#define UPDATE_LOCK_NAME_TOKEN "UpdateLock"
+
+nsUpdateSyncManager* gUpdateSyncManager = nullptr;
+
+NS_IMPL_ISUPPORTS(nsUpdateSyncManager, nsIUpdateSyncManager, nsIObserver)
+
+nsUpdateSyncManager::nsUpdateSyncManager() { OpenLock(); }
+
+nsUpdateSyncManager::~nsUpdateSyncManager() {
+  ReleaseLock();
+  gUpdateSyncManager = nullptr;
+}
+
+already_AddRefed<nsUpdateSyncManager> nsUpdateSyncManager::GetSingleton() {
+  if (!gUpdateSyncManager) {
+    gUpdateSyncManager = new nsUpdateSyncManager();
+  }
+  return do_AddRef(gUpdateSyncManager);
+}
+
+NS_IMETHODIMP nsUpdateSyncManager::Observe(nsISupports* aSubject,
+                                           const char* aTopic,
+                                           const char16_t* aData) {
+  mozilla::Unused << aSubject;
+  mozilla::Unused << aData;
+
+  // We want to hold the lock for as much of the lifetime of the app as we can,
+  // so we observe xpcom-startup so we get constructed as early as possible,
+  // which triggers constructing the singleton.
+  if (!nsCRT::strcmp(aTopic, NS_XPCOM_STARTUP_OBSERVER_ID)) {
+    nsCOMPtr<nsIObserverService> observerService =
+        mozilla::services::GetObserverService();
+    if (observerService) {
+      return observerService->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID,
+                                          false);
+    }
+    return NS_ERROR_SERVICE_NOT_AVAILABLE;
+  }
+  if (!nsCRT::strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
+    ReleaseLock();
+  }
+
+  return NS_OK;
+}
+
+nsresult nsUpdateSyncManager::OpenLock() {
+  if (mLock != MULTI_INSTANCE_LOCK_HANDLE_ERROR) {
+    // Lock is already open.
+    return NS_OK;
+  }
+
+  // Only open the lock from the browser process.
+  // Our component registration should already have made sure of this.
+  if (NS_WARN_IF(XRE_GetProcessType() != GeckoProcessType_Default)) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIProperties> dirSvc =
+      do_GetService(NS_DIRECTORY_SERVICE_CONTRACTID);
+  NS_ENSURE_TRUE(dirSvc, NS_ERROR_SERVICE_NOT_AVAILABLE);
+
+  nsCOMPtr<nsIFile> appFile;
+  nsresult rv = dirSvc->Get(XRE_EXECUTABLE_FILE, NS_GET_IID(nsIFile),
+                            getter_AddRefs(appFile));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIFile> appDirFile;
+  rv = appFile->GetParent(getter_AddRefs(appDirFile));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoString appDirPath;
+  rv = appDirFile->GetPath(appDirPath);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  mLock = mozilla::OpenMultiInstanceLock(UPDATE_LOCK_NAME_TOKEN,
+                                         PromiseFlatString(appDirPath).get());
+  NS_ENSURE_TRUE(mLock, NS_ERROR_FAILURE);
+
+  return NS_OK;
+}
+
+void nsUpdateSyncManager::ReleaseLock() {
+  if (mLock == MULTI_INSTANCE_LOCK_HANDLE_ERROR) {
+    // Lock is already released.
+    return;
+  }
+
+  mozilla::ReleaseMultiInstanceLock(mLock);
+  mLock = MULTI_INSTANCE_LOCK_HANDLE_ERROR;
+}
+
+NS_IMETHODIMP nsUpdateSyncManager::IsOtherInstanceRunning(bool* aResult) {
+  if (NS_WARN_IF(XRE_GetProcessType() != GeckoProcessType_Default)) {
+    return NS_ERROR_SERVICE_NOT_AVAILABLE;
+  }
+
+  if (mLock == MULTI_INSTANCE_LOCK_HANDLE_ERROR) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  bool rv = mozilla::IsOtherInstanceRunning(mLock, aResult);
+  NS_ENSURE_TRUE(rv, NS_ERROR_FAILURE);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsUpdateSyncManager::ResetLock() {
+  ReleaseLock();
+  return OpenLock();
+}