Bug 1579367 - Initialize XPCJSContext explicitly, after loading user prefs. r=kmag

This way we get the correct values for start-up prefs in the parent process.

Differential Revision: https://phabricator.services.mozilla.com/D51061

--HG--
extra : moz-landing-system : lando

caps/nsScriptSecurityManager.cpp

@@ -85,7 +85,6 @@ using namespace mozilla;
 using namespace mozilla::dom;
 
 nsIIOService* nsScriptSecurityManager::sIOService = nullptr;
-JSContext* nsScriptSecurityManager::sContext = nullptr;
 bool nsScriptSecurityManager::sStrictFileOriginPolicy = true;
 
 namespace {
@@ -1371,22 +1370,28 @@ nsresult nsScriptSecurityManager::Init() {
 
   mSystemPrincipal = system;
 
+  return NS_OK;
+}
+
+void nsScriptSecurityManager::InitJSCallbacks(JSContext* aCx) {
   //-- Register security check callback in the JS engine
   //   Currently this is used to control access to function.caller
-  sContext = danger::GetJSContext();
 
   static const JSSecurityCallbacks securityCallbacks = {
       ContentSecurityPolicyPermitsJSAction,
       JSPrincipalsSubsume,
   };
 
-  MOZ_ASSERT(!JS_GetSecurityCallbacks(sContext));
-  JS_SetSecurityCallbacks(sContext, &securityCallbacks);
-  JS_InitDestroyPrincipalsCallback(sContext, nsJSPrincipals::Destroy);
+  MOZ_ASSERT(!JS_GetSecurityCallbacks(aCx));
+  JS_SetSecurityCallbacks(aCx, &securityCallbacks);
+  JS_InitDestroyPrincipalsCallback(aCx, nsJSPrincipals::Destroy);
 
-  JS_SetTrustedPrincipals(sContext, system);
+  JS_SetTrustedPrincipals(aCx, BasePrincipal::Cast(mSystemPrincipal));
+}
 
-  return NS_OK;
+void nsScriptSecurityManager::ClearJSCallbacks(JSContext* aCx) {
+  JS_SetSecurityCallbacks(aCx, nullptr);
+  JS_SetTrustedPrincipals(aCx, nullptr);
 }
 
 static StaticRefPtr<nsScriptSecurityManager> gScriptSecMan;
@@ -1404,12 +1409,6 @@ nsScriptSecurityManager::~nsScriptSecurityManager(void) {
 }
 
 void nsScriptSecurityManager::Shutdown() {
-  if (sContext) {
-    JS_SetSecurityCallbacks(sContext, nullptr);
-    JS_SetTrustedPrincipals(sContext, nullptr);
-    sContext = nullptr;
-  }
-
   NS_IF_RELEASE(sIOService);
   BundleHelper::Shutdown();
 }

caps/nsScriptSecurityManager.h

@@ -51,6 +51,9 @@ class nsScriptSecurityManager final : public nsIScriptSecurityManager {
   // Invoked exactly once, by XPConnect.
   static void InitStatics();
 
+  void InitJSCallbacks(JSContext* aCx);
+  void ClearJSCallbacks(JSContext* aCx);
+
   static already_AddRefed<mozilla::SystemPrincipal>
   SystemPrincipalSingletonConstructor();
 
@@ -121,7 +124,6 @@ class nsScriptSecurityManager final : public nsIScriptSecurityManager {
 
   static nsIIOService* sIOService;
   static nsIStringBundle* sStrBundle;
-  static JSContext* sContext;
 };
 
 #endif  // nsScriptSecurityManager_h__

js/xpconnect/src/XPCJSContext.cpp

@@ -1262,6 +1262,10 @@ nsresult XPCJSContext::Initialize() {
   Preferences::RegisterCallback(ReloadPrefsCallback, "fuzzing.enabled", this);
 #endif
 
+  MOZ_RELEASE_ASSERT(JS::InitSelfHostedCode(cx), "InitSelfHostedCode failed");
+  MOZ_RELEASE_ASSERT(Runtime()->InitializeStrings(cx),
+                     "InitializeStrings failed");
+
   return NS_OK;
 }
 

js/xpconnect/src/XPCJSRuntime.cpp

@@ -32,6 +32,7 @@
 #include "nsIPlatformInfo.h"
 #include "nsPIDOMWindow.h"
 #include "nsPrintfCString.h"
+#include "nsScriptSecurityManager.h"
 #include "nsThreadPool.h"
 #include "nsWindowSizes.h"
 #include "mozilla/Preferences.h"
@@ -1120,6 +1121,8 @@ void XPCJSRuntime::Shutdown(JSContext* cx) {
 
   JS::SetGCSliceCallback(cx, mPrevGCSliceCallback);
 
+  nsScriptSecurityManager::GetScriptSecurityManager()->ClearJSCallbacks(cx);
+
   // Shut down the helper threads
   gHelperThreads->Shutdown();
   gHelperThreads = nullptr;
@@ -3050,6 +3053,8 @@ void XPCJSRuntime::Initialize(JSContext* cx) {
   // these jsids filled in later when we have a JSContext to work with.
   mStrIDs[0] = JSID_VOID;
 
+  nsScriptSecurityManager::GetScriptSecurityManager()->InitJSCallbacks(cx);
+
   // Unconstrain the runtime's threshold on nominal heap size, to avoid
   // triggering GC too often if operating continuously near an arbitrary
   // finite threshold (0xffffffff is infinity for uint32_t parameters).

js/xpconnect/src/nsXPConnect.cpp

@@ -26,6 +26,7 @@
 #include "mozilla/dom/DOMException.h"
 #include "mozilla/dom/Exceptions.h"
 #include "mozilla/dom/Promise.h"
+#include "mozilla/ScriptPreloader.h"
 
 #include "nsDOMMutationObserver.h"
 #include "nsICycleCollectorListener.h"
@@ -71,17 +72,35 @@ nsXPConnect::nsXPConnect() : mShuttingDown(false) {
   JS::SetProfilingThreadCallbacks(profiler_register_thread,
                                   profiler_unregister_thread);
 #endif
+}
+
+// static
+void nsXPConnect::InitJSContext() {
+  MOZ_ASSERT(!gContext);
 
   XPCJSContext* xpccx = XPCJSContext::NewXPCJSContext();
   if (!xpccx) {
     MOZ_CRASH("Couldn't create XPCJSContext.");
   }
   gContext = xpccx;
-  mRuntime = xpccx->Runtime();
+  gSelf->mRuntime = xpccx->Runtime();
+
+  // Initialize our singleton scopes.
+  gSelf->mRuntime->InitSingletonScopes();
+
+  mozJSComponentLoader::InitStatics();
+
+  // Initialize the script preloader cache.
+  Unused << mozilla::ScriptPreloader::GetSingleton();
+
+  nsJSContext::EnsureStatics();
 }
 
+void xpc::InitializeJSContext() { nsXPConnect::InitJSContext(); }
+
 nsXPConnect::~nsXPConnect() {
   MOZ_ASSERT(XPCJSContext::Get() == gContext);
+  MOZ_ASSERT(mRuntime);
 
   mRuntime->DeleteSingletonScopes();
 
@@ -136,19 +155,6 @@ void nsXPConnect::InitStatics() {
   gScriptSecurityManager = nsScriptSecurityManager::GetScriptSecurityManager();
   gScriptSecurityManager->GetSystemPrincipal(&gSystemPrincipal);
   MOZ_RELEASE_ASSERT(gSystemPrincipal);
-
-  JSContext* cx = XPCJSContext::Get()->Context();
-  if (!JS::InitSelfHostedCode(cx)) {
-    MOZ_CRASH("InitSelfHostedCode failed");
-  }
-  if (!gSelf->mRuntime->InitializeStrings(cx)) {
-    MOZ_CRASH("InitializeStrings failed");
-  }
-
-  // Initialize our singleton scopes.
-  gSelf->mRuntime->InitSingletonScopes();
-
-  mozJSComponentLoader::InitStatics();
 }
 
 // static

js/xpconnect/src/xpcprivate.h

@@ -246,6 +246,8 @@ class nsXPConnect final : public nsIXPConnect {
   // Called by module code on dll shutdown.
   static void ReleaseXPConnectSingleton();
 
+  static void InitJSContext();
+
   void RecordTraversal(void* p, nsISupports* s);
 
  protected:
@@ -258,7 +260,7 @@ class nsXPConnect final : public nsIXPConnect {
   static nsXPConnect* gSelf;
   static bool gOnceAliveNowDead;
 
-  XPCJSRuntime* mRuntime;
+  XPCJSRuntime* mRuntime = nullptr;
   bool mShuttingDown;
 
   friend class nsIXPConnect;

js/xpconnect/src/xpcpublic.h

@@ -683,6 +683,8 @@ inline bool IsInAutomation() {
   return sAutomationPrefIsSet && AreNonLocalConnectionsDisabled();
 }
 
+void InitializeJSContext();
+
 /**
  * Extract the native nsID object from a JS ID, IfaceID, ClassID, or ContractID
  * value.

layout/build/nsLayoutStatics.cpp

@@ -161,7 +161,6 @@ nsresult nsLayoutStatics::Initialize() {
 #endif
 
   StartupJSEnvironment();
-  nsJSContext::EnsureStatics();
 
   nsGlobalWindowInner::Init();
   nsGlobalWindowOuter::Init();

modules/libpref/Preferences.cpp

@@ -3668,7 +3668,10 @@ void Preferences::InitializeUserPrefs() {
 
   // Don't set mCurrentFile until we're done so that dirty flags work properly.
   sPreferences->mCurrentFile = prefsFile.forget();
+}
 
+/* static */
+void Preferences::FinishInitializingUserPrefs() {
   sPreferences->NotifyServiceObservers(NS_PREFSERVICE_READ_TOPIC_ID);
 
   // At this point all the prefs files have been read and telemetry has been

modules/libpref/Preferences.h

@@ -108,6 +108,7 @@ class Preferences final : public nsIPrefService,
 
   // Initialize user prefs from prefs.js/user.js
   static void InitializeUserPrefs();
+  static void FinishInitializingUserPrefs();
 
   // Returns the singleton instance which is addreffed.
   static already_AddRefed<Preferences> GetInstanceForService();

toolkit/xre/nsAppRunner.cpp

@@ -1202,7 +1202,7 @@ class ScopedXPCOMStartup {
   ScopedXPCOMStartup() : mServiceManager(nullptr) {}
   ~ScopedXPCOMStartup();
 
-  nsresult Initialize();
+  nsresult Initialize(bool aInitJSContext = true);
   nsresult SetWindowCreator(nsINativeAppSupport* native);
 
  private:
@@ -1259,13 +1259,13 @@ static const mozilla::Module::ContractIDEntry kXREContracts[] = {
 extern const mozilla::Module kXREModule = {mozilla::Module::kVersion, kXRECIDs,
                                            kXREContracts};
 
-nsresult ScopedXPCOMStartup::Initialize() {
+nsresult ScopedXPCOMStartup::Initialize(bool aInitJSContext) {
   NS_ASSERTION(gDirServiceProvider, "Should not get here!");
 
   nsresult rv;
 
   rv = NS_InitXPCOM(&mServiceManager, gDirServiceProvider->GetAppDir(),
-                    gDirServiceProvider);
+                    gDirServiceProvider, aInitJSContext);
   if (NS_FAILED(rv)) {
     NS_ERROR("Couldn't start xpcom!");
     mServiceManager = nullptr;
@@ -4344,10 +4344,21 @@ nsresult XREMain::XRE_mainRun() {
     }
   }
 
+  // We'd like to initialize the JSContext *after* reading the user prefs.
+  // Unfortunately that's not possible if we have to do profile migration
+  // because that requires us to execute JS before reading user prefs.
+  // Restarting the browser after profile migration would fix this. See
+  // bug 1592523.
+  bool initializedJSContext = false;
+
   {
     // Profile Migration
     if (mAppData->flags & NS_XRE_ENABLE_PROFILE_MIGRATOR && gDoMigration) {
       gDoMigration = false;
+
+      xpc::InitializeJSContext();
+      initializedJSContext = true;
+
       nsCOMPtr<nsIProfileMigrator> pm(
           do_CreateInstance(NS_PROFILEMIGRATOR_CONTRACTID));
       if (pm) {
@@ -4389,6 +4400,18 @@ nsresult XREMain::XRE_mainRun() {
   // ready in time for early consumers, such as the component loader.
   mDirProvider.InitializeUserPrefs();
 
+  // Now that all (user) prefs have been loaded we can initialize the main
+  // thread's JSContext.
+  if (!initializedJSContext) {
+    xpc::InitializeJSContext();
+  }
+
+  // Finally, now that JS has been initialized, we can finish pref loading. This
+  // needs to happen after JS and XPConnect initialization because AutoConfig
+  // files require JS execution. Note that this means AutoConfig files can't
+  // override JS engine start-up prefs.
+  mDirProvider.FinishInitializingUserPrefs();
+
   nsAppStartupNotifier::NotifyObservers(APPSTARTUP_CATEGORY);
 
   nsCOMPtr<nsIAppStartup> appStartup(components::AppStartup::Service());
@@ -4710,11 +4733,13 @@ int XREMain::XRE_main(int argc, char* argv[], const BootstrapConfig& aConfig) {
 
   bool appInitiatedRestart = false;
 
-  // Start the real application
+  // Start the real application. We use |aInitJSContext = false| because
+  // XRE_mainRun wants to initialize the JSContext after reading user prefs.
+
   mScopedXPCOM = MakeUnique<ScopedXPCOMStartup>();
   if (!mScopedXPCOM) return 1;
 
-  rv = mScopedXPCOM->Initialize();
+  rv = mScopedXPCOM->Initialize(/* aInitJSContext = */ false);
   NS_ENSURE_SUCCESS(rv, 1);
 
   // run!

toolkit/xre/nsXREDirProvider.cpp

@@ -884,6 +884,17 @@ void nsXREDirProvider::InitializeUserPrefs() {
     mProfileNotified = true;
 
     mozilla::Preferences::InitializeUserPrefs();
+  }
+}
+
+void nsXREDirProvider::FinishInitializingUserPrefs() {
+  if (!mPrefsInitialized) {
+    // See InitializeUserPrefs above.
+    mozilla::AutoRestore<bool> ar(mProfileNotified);
+    mProfileNotified = true;
+
+    mozilla::Preferences::FinishInitializingUserPrefs();
+
     mPrefsInitialized = true;
   }
 }

toolkit/xre/nsXREDirProvider.h

@@ -59,6 +59,7 @@ class nsXREDirProvider final : public nsIDirectoryServiceProvider2,
   nsresult SetProfile(nsIFile* aProfileDir, nsIFile* aProfileLocalDir);
 
   void InitializeUserPrefs();
+  void FinishInitializingUserPrefs();
 
   void DoShutdown();
 

xpcom/build/XPCOMInit.cpp

@@ -248,7 +248,8 @@ static bool sInitializedJS = false;
 // Note that on OSX, aBinDirectory will point to .app/Contents/Resources/browser
 EXPORT_XPCOM_API(nsresult)
 NS_InitXPCOM(nsIServiceManager** aResult, nsIFile* aBinDirectory,
-             nsIDirectoryServiceProvider* aAppFileLocationProvider) {
+             nsIDirectoryServiceProvider* aAppFileLocationProvider,
+             bool aInitJSContext) {
   static bool sInitialized = false;
   if (sInitialized) {
     return NS_ERROR_FAILURE;
@@ -461,7 +462,6 @@ NS_InitXPCOM(nsIServiceManager** aResult, nsIFile* aBinDirectory,
   // Init mozilla::SharedThreadPool (which needs the service manager).
   mozilla::SharedThreadPool::InitStatics();
 
-  mozilla::ScriptPreloader::GetSingleton();
   mozilla::scache::StartupCache::GetSingleton();
   mozilla::AvailableMemoryTracker::Init();
 
@@ -485,6 +485,10 @@ NS_InitXPCOM(nsIServiceManager** aResult, nsIFile* aBinDirectory,
       loop->thread_name().c_str(), loop->transient_hang_timeout(),
       loop->permanent_hang_timeout());
 
+  if (aInitJSContext) {
+    xpc::InitializeJSContext();
+  }
+
   return NS_OK;
 }
 

xpcom/build/nsXPCOM.h

@@ -63,6 +63,9 @@ struct Module;
  *                         component registry preferences and so on; or use
  *                         <CODE>nullptr</CODE> for the default behaviour.
  *
+ * @param aInitJSContext   Whether the nsXPCJSContext should be initialized at
+ *                         this point.
+ *
  * @see NS_NewLocalFile
  * @see nsIFile
  * @see nsIDirectoryServiceProvider
@@ -75,7 +78,8 @@ struct Module;
  */
 XPCOM_API(nsresult)
 NS_InitXPCOM(nsIServiceManager** aResult, nsIFile* aBinDirectory,
-             nsIDirectoryServiceProvider* aAppFileLocationProvider);
+             nsIDirectoryServiceProvider* aAppFileLocationProvider,
+             bool aInitJSContext = true);
 
 /**
  * Initialize only minimal components of XPCOM. This ensures nsThreadManager,