The Tor Browser: js/xpconnect/src/nsCxPusher.cpp@6474c204b198 (annotated)

js/xpconnect/src/nsCxPusher.cpp@6474c204b198 (annotated)

js/xpconnect/src/nsCxPusher.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* 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 "nsCxPusher.h"
 #include "nsIScriptContext.h"
 #include "mozilla/dom/EventTarget.h"
 #include "nsDOMJSUtils.h"
 #include "xpcprivate.h"
 #include "WorkerPrivate.h"
 using mozilla::dom::EventTarget;
 using mozilla::DebugOnly;
 bool
 nsCxPusher::Push(EventTarget *aCurrentTarget)
 {
   MOZ_ASSERT(mPusher.empty());
   NS_ENSURE_TRUE(aCurrentTarget, false);
   nsresult rv;
   nsIScriptContext* scx =
     aCurrentTarget->GetContextForEventHandlers(&rv);
 #ifdef DEBUG_smaug
   NS_ENSURE_SUCCESS(rv, false);
 #else
   if(NS_FAILED(rv)) {
     return false;
   }
 #endif
   if (!scx) {
     // The target may have a special JS context for event handlers.
     JSContext* cx = aCurrentTarget->GetJSContextForEventHandlers();
     if (cx) {
       mPusher.construct(cx);
     }
     // Nothing to do here, I guess.  Have to return true so that event firing
     // will still work correctly even if there is no associated JSContext
     return true;
   }
   mPusher.construct(scx->GetNativeContext());
   return true;
 }
 bool
 nsCxPusher::RePush(EventTarget *aCurrentTarget)
 {
   if (mPusher.empty()) {
     return Push(aCurrentTarget);
   }
   if (aCurrentTarget) {
     nsresult rv;
     nsIScriptContext* scx =
       aCurrentTarget->GetContextForEventHandlers(&rv);
     if (NS_FAILED(rv)) {
       mPusher.destroy();
       return false;
     }
     // If we have the same script context and native context is still
     // alive, no need to Pop/Push.
     if (scx && scx == mPusher.ref().GetScriptContext() &&
         scx->GetNativeContext()) {
       return true;
     }
   }
   mPusher.destroy();
   return Push(aCurrentTarget);
 }
 void
 nsCxPusher::Push(JSContext *cx)
 {
   mPusher.construct(cx);
 }
 void
 nsCxPusher::PushNull()
 {
   // Note: The Maybe<> template magic seems to need the static_cast below to
   // work right on some older compilers.
   mPusher.construct(static_cast<JSContext*>(nullptr), /* aAllowNull = */ true);
 }
 void
 nsCxPusher::Pop()
 {
   if (!mPusher.empty())
     mPusher.destroy();
 }
 namespace mozilla {
 AutoCxPusher::AutoCxPusher(JSContext* cx, bool allowNull)
 {
   MOZ_ASSERT_IF(!allowNull, cx);
   // Hold a strong ref to the nsIScriptContext, if any. This ensures that we
   // only destroy the mContext of an nsJSContext when it is not on the cx stack
   // (and therefore not in use). See nsJSContext::DestroyJSContext().
   if (cx)
     mScx = GetScriptContextFromJSContext(cx);
   XPCJSContextStack *stack = XPCJSRuntime::Get()->GetJSContextStack();
   if (!stack->Push(cx)) {
     MOZ_CRASH();
   }
   mStackDepthAfterPush = stack->Count();
 #ifdef DEBUG
   mPushedContext = cx;
   mCompartmentDepthOnEntry = cx ? js::GetEnterCompartmentDepth(cx) : 0;
 #endif
   // Enter a request and a compartment for the duration that the cx is on the
   // stack if non-null.
   if (cx) {
     mAutoRequest.construct(cx);
     // DOM JSContexts don't store their default compartment object on the cx.
     JSObject *compartmentObject = mScx ? mScx->GetWindowProxy()
                                        : js::DefaultObjectForContextOrNull(cx);
     if (compartmentObject)
       mAutoCompartment.construct(cx, compartmentObject);
   }
 }
 AutoCxPusher::~AutoCxPusher()
 {
   // GC when we pop a script entry point. This is a useful heuristic that helps
   // us out on certain (flawed) benchmarks like sunspider, because it lets us
   // avoid GCing during the timing loop.
   //
   // NB: We need to take care to only do this if we're in a compartment,
   // otherwise JS_MaybeGC will segfault.
   if (mScx && !mAutoCompartment.empty())
     JS_MaybeGC(nsXPConnect::XPConnect()->GetCurrentJSContext());
   // Leave the compartment and request before popping.
   mAutoCompartment.destroyIfConstructed();
   mAutoRequest.destroyIfConstructed();
   // When we push a context, we may save the frame chain and pretend like we
   // haven't entered any compartment. This gets restored on Pop(), but we can
   // run into trouble if a Push/Pop are interleaved with a
   // JSAutoEnterCompartment. Make sure the compartment depth right before we
   // pop is the same as it was right after we pushed.
   MOZ_ASSERT_IF(mPushedContext, mCompartmentDepthOnEntry ==
                                 js::GetEnterCompartmentDepth(mPushedContext));
   DebugOnly<JSContext*> stackTop;
   MOZ_ASSERT(mPushedContext == nsXPConnect::XPConnect()->GetCurrentJSContext());
   XPCJSRuntime::Get()->GetJSContextStack()->Pop();
   mScx = nullptr;
 }
 bool
 AutoCxPusher::IsStackTop()
 {
   uint32_t currentDepth = XPCJSRuntime::Get()->GetJSContextStack()->Count();
   MOZ_ASSERT(currentDepth >= mStackDepthAfterPush);
   return currentDepth == mStackDepthAfterPush;
 }
 AutoJSContext::AutoJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
   : mCx(nullptr)
 {
   Init(false MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT);
 }
 AutoJSContext::AutoJSContext(bool aSafe MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
   : mCx(nullptr)
 {
   Init(aSafe MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT);
 }
 void
 AutoJSContext::Init(bool aSafe MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
 {
   JS::AutoAssertNoGC nogc;
   MOZ_ASSERT(!mCx, "mCx should not be initialized!");
   MOZ_GUARD_OBJECT_NOTIFIER_INIT;
   nsXPConnect *xpc = nsXPConnect::XPConnect();
   if (!aSafe) {
     mCx = xpc->GetCurrentJSContext();
   }
   if (!mCx) {
     mCx = xpc->GetSafeJSContext();
     mPusher.construct(mCx);
   }
 }
 AutoJSContext::operator JSContext*() const
 {
   return mCx;
 }
 ThreadsafeAutoJSContext::ThreadsafeAutoJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
 {
   MOZ_GUARD_OBJECT_NOTIFIER_INIT;
   if (NS_IsMainThread()) {
     mCx = nullptr;
     mAutoJSContext.construct();
   } else {
     mCx = mozilla::dom::workers::GetCurrentThreadJSContext();
     mRequest.construct(mCx);
   }
 }
 ThreadsafeAutoJSContext::operator JSContext*() const
 {
   if (mCx) {
     return mCx;
   } else {
     return mAutoJSContext.ref();
   }
 }
 AutoSafeJSContext::AutoSafeJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
   : AutoJSContext(true MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)
   , mAc(mCx, XPCJSRuntime::Get()->GetJSContextStack()->GetSafeJSContextGlobal())
 {
 }
 ThreadsafeAutoSafeJSContext::ThreadsafeAutoSafeJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
 {
   MOZ_GUARD_OBJECT_NOTIFIER_INIT;
   if (NS_IsMainThread()) {
     mCx = nullptr;
     mAutoSafeJSContext.construct();
   } else {
     mCx = mozilla::dom::workers::GetCurrentThreadJSContext();
     mRequest.construct(mCx);
   }
 }
 ThreadsafeAutoSafeJSContext::operator JSContext*() const
 {
   if (mCx) {
     return mCx;
   } else {
     return mAutoSafeJSContext.ref();
   }
 }
 AutoPushJSContext::AutoPushJSContext(JSContext *aCx) : mCx(aCx)
 {
   if (mCx && mCx != nsXPConnect::XPConnect()->GetCurrentJSContext()) {
     mPusher.construct(mCx);
   }
 }
 } // namespace mozilla

The Tor Browser / annotate

js/xpconnect/src/nsCxPusher.cpp@6474c204b198 (annotated)

js/xpconnect/src/nsCxPusher.cpp