The Tor Browser: js/xpconnect/src/XPCJSContextStack.cpp@b8a032363ba2 (annotated)

js/xpconnect/src/XPCJSContextStack.cpp@b8a032363ba2 (annotated)

js/xpconnect/src/XPCJSContextStack.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* vim: set ts=8 sts=4 et sw=4 tw=99: */
 /* 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/. */
 /* Implement global service to track stack of JSContext. */
 #include "xpcprivate.h"
 #include "XPCWrapper.h"
 #include "nsDOMJSUtils.h"
 #include "nsNullPrincipal.h"
 #include "mozilla/dom/BindingUtils.h"
 using namespace mozilla;
 using namespace JS;
 using namespace xpc;
 using mozilla::dom::DestroyProtoAndIfaceCache;
 /***************************************************************************/
 XPCJSContextStack::~XPCJSContextStack()
 {
     if (mSafeJSContext) {
         mSafeJSContextGlobal = nullptr;
         JS_DestroyContextNoGC(mSafeJSContext);
         mSafeJSContext = nullptr;
     }
 }
 JSContext*
 XPCJSContextStack::Pop()
 {
     MOZ_ASSERT(!mStack.IsEmpty());
     uint32_t idx = mStack.Length() - 1; // The thing we're popping
     JSContext *cx = mStack[idx].cx;
     mStack.RemoveElementAt(idx);
     if (idx == 0) {
         js::Debug_SetActiveJSContext(mRuntime->Runtime(), nullptr);
         return cx;
     }
     --idx; // Advance to new top of the stack
     XPCJSContextInfo &e = mStack[idx];
     if (e.cx && e.savedFrameChain) {
         // Pop() can be called outside any request for e.cx.
         JSAutoRequest ar(e.cx);
         JS_RestoreFrameChain(e.cx);
         e.savedFrameChain = false;
     }
     js::Debug_SetActiveJSContext(mRuntime->Runtime(), e.cx);
     return cx;
 }
 bool
 XPCJSContextStack::Push(JSContext *cx)
 {
     js::Debug_SetActiveJSContext(mRuntime->Runtime(), cx);
     if (mStack.Length() == 0) {
         mStack.AppendElement(cx);
         return true;
     }
     XPCJSContextInfo &e = mStack[mStack.Length() - 1];
     if (e.cx) {
         // The cx we're pushing is also stack-top. In general we still need to
         // call JS_SaveFrameChain here. But if that would put us in a
         // compartment that's same-origin with the current one, we can skip it.
         nsIScriptSecurityManager* ssm = XPCWrapper::GetSecurityManager();
         if ((e.cx == cx) && ssm) {
             // DOM JSContexts don't store their default compartment object on
             // the cx, so in those cases we need to fetch it via the scx
             // instead. And in some cases (i.e. the SafeJSContext), we have no
             // default compartment object at all.
             RootedObject defaultScope(cx, GetDefaultScopeFromJSContext(cx));
             if (defaultScope) {
                 nsIPrincipal *currentPrincipal =
                   GetCompartmentPrincipal(js::GetContextCompartment(cx));
                 nsIPrincipal *defaultPrincipal = GetObjectPrincipal(defaultScope);
                 if (currentPrincipal->Equals(defaultPrincipal)) {
                     mStack.AppendElement(cx);
                     return true;
                 }
             }
         }
         {
             // Push() can be called outside any request for e.cx.
             JSAutoRequest ar(e.cx);
             if (!JS_SaveFrameChain(e.cx))
                 return false;
             e.savedFrameChain = true;
         }
     }
     mStack.AppendElement(cx);
     return true;
 }
 bool
 XPCJSContextStack::HasJSContext(JSContext *cx)
 {
     for (uint32_t i = 0; i < mStack.Length(); i++)
         if (cx == mStack[i].cx)
             return true;
     return false;
 }
 static bool
 SafeGlobalResolve(JSContext *cx, HandleObject obj, HandleId id)
 {
     bool resolved;
     return JS_ResolveStandardClass(cx, obj, id, &resolved);
 }
 static void
 SafeFinalize(JSFreeOp *fop, JSObject* obj)
 {
     SandboxPrivate* sop =
         static_cast<SandboxPrivate*>(xpc_GetJSPrivate(obj));
     sop->ForgetGlobalObject();
     NS_IF_RELEASE(sop);
     DestroyProtoAndIfaceCache(obj);
 }
 const JSClass xpc::SafeJSContextGlobalClass = {
     "global_for_XPCJSContextStack_SafeJSContext",
     XPCONNECT_GLOBAL_FLAGS,
     JS_PropertyStub, JS_DeletePropertyStub, JS_PropertyStub, JS_StrictPropertyStub,
     JS_EnumerateStub, SafeGlobalResolve, JS_ConvertStub, SafeFinalize,
     nullptr, nullptr, nullptr, JS_GlobalObjectTraceHook
 };
 JSContext*
 XPCJSContextStack::GetSafeJSContext()
 {
     MOZ_ASSERT(mSafeJSContext);
     return mSafeJSContext;
 }
 JSObject*
 XPCJSContextStack::GetSafeJSContextGlobal()
 {
     MOZ_ASSERT(mSafeJSContextGlobal);
     return mSafeJSContextGlobal;
 }
 JSContext*
 XPCJSContextStack::InitSafeJSContext()
 {
     MOZ_ASSERT(!mSafeJSContext);
     // Start by getting the principal holder and principal for this
     // context.  If we can't manage that, don't bother with the rest.
     nsRefPtr<nsNullPrincipal> principal = new nsNullPrincipal();
     nsresult rv = principal->Init();
     if (NS_FAILED(rv))
         MOZ_CRASH();
     nsXPConnect* xpc = nsXPConnect::XPConnect();
     JSRuntime *rt = xpc->GetRuntime()->Runtime();
     if (!rt)
         MOZ_CRASH();
     mSafeJSContext = JS_NewContext(rt, 8192);
     if (!mSafeJSContext)
         MOZ_CRASH();
     JSAutoRequest req(mSafeJSContext);
     ContextOptionsRef(mSafeJSContext).setNoDefaultCompartmentObject(true);
     JS_SetErrorReporter(mSafeJSContext, xpc::SystemErrorReporter);
     JS::CompartmentOptions options;
     options.setZone(JS::SystemZone)
            .setTrace(TraceXPCGlobal);
     mSafeJSContextGlobal = CreateGlobalObject(mSafeJSContext,
                                               &SafeJSContextGlobalClass,
                                               principal, options);
     if (!mSafeJSContextGlobal)
         MOZ_CRASH();
     // Note: make sure to set the private before calling
     // InitClasses
     nsRefPtr<SandboxPrivate> sp = new SandboxPrivate(principal, mSafeJSContextGlobal);
     JS_SetPrivate(mSafeJSContextGlobal, sp.forget().take());
     // After this point either glob is null and the
     // nsIScriptObjectPrincipal ownership is either handled by the
     // nsCOMPtr or dealt with, or we'll release in the finalize
     // hook.
     if (NS_FAILED(xpc->InitClasses(mSafeJSContext, mSafeJSContextGlobal)))
         MOZ_CRASH();
     JS::RootedObject glob(mSafeJSContext, mSafeJSContextGlobal);
     JS_FireOnNewGlobalObject(mSafeJSContext, glob);
     return mSafeJSContext;
 }

The Tor Browser / annotate

js/xpconnect/src/XPCJSContextStack.cpp@b8a032363ba2 (annotated)

js/xpconnect/src/XPCJSContextStack.cpp