michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: // vim: ft=cpp tw=78 sw=2 et ts=2
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "mozilla/dom/ScriptSettings.h"
michael@0: #include "mozilla/ThreadLocal.h"
michael@0: #include "mozilla/Assertions.h"
michael@0: 
michael@0: #include "jsapi.h"
michael@0: #include "xpcpublic.h"
michael@0: #include "nsIGlobalObject.h"
michael@0: #include "nsIScriptGlobalObject.h"
michael@0: #include "nsIScriptContext.h"
michael@0: #include "nsContentUtils.h"
michael@0: #include "nsTArray.h"
michael@0: #include "nsJSUtils.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace dom {
michael@0: 
michael@0: class ScriptSettingsStack;
michael@0: static mozilla::ThreadLocal<ScriptSettingsStack*> sScriptSettingsTLS;
michael@0: 
michael@0: ScriptSettingsStackEntry ScriptSettingsStackEntry::NoJSAPISingleton;
michael@0: 
michael@0: class ScriptSettingsStack {
michael@0: public:
michael@0:   static ScriptSettingsStack& Ref() {
michael@0:     return *sScriptSettingsTLS.get();
michael@0:   }
michael@0:   ScriptSettingsStack() {};
michael@0: 
michael@0:   void Push(ScriptSettingsStackEntry* aSettings) {
michael@0:     // The bottom-most entry must always be a candidate entry point.
michael@0:     MOZ_ASSERT_IF(mStack.Length() == 0 || mStack.LastElement()->NoJSAPI(),
michael@0:                   aSettings->mIsCandidateEntryPoint);
michael@0:     mStack.AppendElement(aSettings);
michael@0:   }
michael@0: 
michael@0:   void PushNoJSAPI() {
michael@0:     mStack.AppendElement(&ScriptSettingsStackEntry::NoJSAPISingleton);
michael@0:   }
michael@0: 
michael@0:   void Pop() {
michael@0:     MOZ_ASSERT(mStack.Length() > 0);
michael@0:     mStack.RemoveElementAt(mStack.Length() - 1);
michael@0:   }
michael@0: 
michael@0:   ScriptSettingsStackEntry* Incumbent() {
michael@0:     if (!mStack.Length()) {
michael@0:       return nullptr;
michael@0:     }
michael@0:     return mStack.LastElement();
michael@0:   }
michael@0: 
michael@0:   nsIGlobalObject* IncumbentGlobal() {
michael@0:     ScriptSettingsStackEntry *entry = Incumbent();
michael@0:     return entry ? entry->mGlobalObject : nullptr;
michael@0:   }
michael@0: 
michael@0:   ScriptSettingsStackEntry* EntryPoint() {
michael@0:     if (!mStack.Length())
michael@0:       return nullptr;
michael@0:     for (int i = mStack.Length() - 1; i >= 0; --i) {
michael@0:       if (mStack[i]->mIsCandidateEntryPoint) {
michael@0:         return mStack[i];
michael@0:       }
michael@0:     }
michael@0:     MOZ_ASSUME_UNREACHABLE("Non-empty stack should always have an entry point");
michael@0:   }
michael@0: 
michael@0:   nsIGlobalObject* EntryGlobal() {
michael@0:     ScriptSettingsStackEntry *entry = EntryPoint();
michael@0:     return entry ? entry->mGlobalObject : nullptr;
michael@0:   }
michael@0: 
michael@0: private:
michael@0:   // These pointers are caller-owned.
michael@0:   nsTArray<ScriptSettingsStackEntry*> mStack;
michael@0: };
michael@0: 
michael@0: void
michael@0: InitScriptSettings()
michael@0: {
michael@0:   if (!sScriptSettingsTLS.initialized()) {
michael@0:     bool success = sScriptSettingsTLS.init();
michael@0:     if (!success) {
michael@0:       MOZ_CRASH();
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   ScriptSettingsStack* ptr = new ScriptSettingsStack();
michael@0:   sScriptSettingsTLS.set(ptr);
michael@0: }
michael@0: 
michael@0: void DestroyScriptSettings()
michael@0: {
michael@0:   ScriptSettingsStack* ptr = sScriptSettingsTLS.get();
michael@0:   MOZ_ASSERT(ptr);
michael@0:   sScriptSettingsTLS.set(nullptr);
michael@0:   delete ptr;
michael@0: }
michael@0: 
michael@0: // This mostly gets the entry global, but doesn't entirely match the spec in
michael@0: // certain edge cases. It's good enough for some purposes, but not others. If
michael@0: // you want to call this function, ping bholley and describe your use-case.
michael@0: nsIGlobalObject*
michael@0: BrokenGetEntryGlobal()
michael@0: {
michael@0:   // We need the current JSContext in order to check the JS for
michael@0:   // scripted frames that may have appeared since anyone last
michael@0:   // manipulated the stack. If it's null, that means that there
michael@0:   // must be no entry global on the stack.
michael@0:   JSContext *cx = nsContentUtils::GetCurrentJSContextForThread();
michael@0:   if (!cx) {
michael@0:     MOZ_ASSERT(ScriptSettingsStack::Ref().EntryGlobal() == nullptr);
michael@0:     return nullptr;
michael@0:   }
michael@0: 
michael@0:   return nsJSUtils::GetDynamicScriptGlobal(cx);
michael@0: }
michael@0: 
michael@0: // Note: When we're ready to expose it, GetEntryGlobal will look similar to
michael@0: // GetIncumbentGlobal below.
michael@0: 
michael@0: nsIGlobalObject*
michael@0: GetIncumbentGlobal()
michael@0: {
michael@0:   // We need the current JSContext in order to check the JS for
michael@0:   // scripted frames that may have appeared since anyone last
michael@0:   // manipulated the stack. If it's null, that means that there
michael@0:   // must be no entry global on the stack, and therefore no incumbent
michael@0:   // global either.
michael@0:   JSContext *cx = nsContentUtils::GetCurrentJSContextForThread();
michael@0:   if (!cx) {
michael@0:     MOZ_ASSERT(ScriptSettingsStack::Ref().EntryGlobal() == nullptr);
michael@0:     return nullptr;
michael@0:   }
michael@0: 
michael@0:   // See what the JS engine has to say. If we've got a scripted caller
michael@0:   // override in place, the JS engine will lie to us and pretend that
michael@0:   // there's nothing on the JS stack, which will cause us to check the
michael@0:   // incumbent script stack below.
michael@0:   if (JSObject *global = JS::GetScriptedCallerGlobal(cx)) {
michael@0:     return xpc::GetNativeForGlobal(global);
michael@0:   }
michael@0: 
michael@0:   // Ok, nothing from the JS engine. Let's use whatever's on the
michael@0:   // explicit stack.
michael@0:   return ScriptSettingsStack::Ref().IncumbentGlobal();
michael@0: }
michael@0: 
michael@0: nsIPrincipal*
michael@0: GetWebIDLCallerPrincipal()
michael@0: {
michael@0:   MOZ_ASSERT(NS_IsMainThread());
michael@0:   ScriptSettingsStackEntry *entry = ScriptSettingsStack::Ref().EntryPoint();
michael@0: 
michael@0:   // If we have an entry point that is not the NoJSAPI singleton, we know it
michael@0:   // must be an AutoEntryScript.
michael@0:   if (!entry || entry->NoJSAPI()) {
michael@0:     return nullptr;
michael@0:   }
michael@0:   AutoEntryScript* aes = static_cast<AutoEntryScript*>(entry);
michael@0: 
michael@0:   // We can't yet rely on the Script Settings Stack to properly determine the
michael@0:   // entry script, because there are still lots of places in the tree where we
michael@0:   // don't yet use an AutoEntryScript (bug 951991 tracks this work). In the
michael@0:   // mean time though, we can make some observations to hack around the
michael@0:   // problem:
michael@0:   //
michael@0:   // (1) All calls into JS-implemented WebIDL go through CallSetup, which goes
michael@0:   //     through AutoEntryScript.
michael@0:   // (2) The top candidate entry point in the Script Settings Stack is the
michael@0:   //     entry point if and only if no other JSContexts have been pushed on
michael@0:   //     top of the push made by that entry's AutoEntryScript.
michael@0:   //
michael@0:   // Because of (1), all of the cases where we might return a non-null
michael@0:   // WebIDL Caller are guaranteed to have put an entry on the Script Settings
michael@0:   // Stack, so we can restrict our search to that. Moreover, (2) gives us a
michael@0:   // criterion to determine whether an entry in the Script Setting Stack means
michael@0:   // that we should return a non-null WebIDL Caller.
michael@0:   //
michael@0:   // Once we fix bug 951991, this can all be simplified.
michael@0:   if (!aes->CxPusherIsStackTop()) {
michael@0:     return nullptr;
michael@0:   }
michael@0: 
michael@0:   return aes->mWebIDLCallerPrincipal;
michael@0: }
michael@0: 
michael@0: static JSContext*
michael@0: FindJSContext(nsIGlobalObject* aGlobalObject)
michael@0: {
michael@0:   MOZ_ASSERT(NS_IsMainThread());
michael@0:   JSContext *cx = nullptr;
michael@0:   nsCOMPtr<nsIScriptGlobalObject> sgo = do_QueryInterface(aGlobalObject);
michael@0:   if (sgo && sgo->GetScriptContext()) {
michael@0:     cx = sgo->GetScriptContext()->GetNativeContext();
michael@0:   }
michael@0:   if (!cx) {
michael@0:     cx = nsContentUtils::GetSafeJSContext();
michael@0:   }
michael@0:   return cx;
michael@0: }
michael@0: 
michael@0: AutoJSAPI::AutoJSAPI()
michael@0:   : mCx(nsContentUtils::GetDefaultJSContextForThread())
michael@0: {
michael@0:   if (NS_IsMainThread()) {
michael@0:     mCxPusher.construct(mCx);
michael@0:   }
michael@0: 
michael@0:   // Leave the cx in a null compartment.
michael@0:   mNullAc.construct(mCx);
michael@0: }
michael@0: 
michael@0: AutoJSAPI::AutoJSAPI(JSContext *aCx, bool aIsMainThread, bool aSkipNullAc)
michael@0:   : mCx(aCx)
michael@0: {
michael@0:   MOZ_ASSERT_IF(aIsMainThread, NS_IsMainThread());
michael@0:   if (aIsMainThread) {
michael@0:     mCxPusher.construct(mCx);
michael@0:   }
michael@0: 
michael@0:   // In general we want to leave the cx in a null compartment, but we let
michael@0:   // subclasses skip this if they plan to immediately enter a compartment.
michael@0:   if (!aSkipNullAc) {
michael@0:     mNullAc.construct(mCx);
michael@0:   }
michael@0: }
michael@0: 
michael@0: AutoJSAPIWithErrorsReportedToWindow::AutoJSAPIWithErrorsReportedToWindow(nsIScriptContext* aScx)
michael@0:   : AutoJSAPI(aScx->GetNativeContext(), /* aIsMainThread = */ true)
michael@0: {
michael@0: }
michael@0: 
michael@0: AutoJSAPIWithErrorsReportedToWindow::AutoJSAPIWithErrorsReportedToWindow(nsIGlobalObject* aGlobalObject)
michael@0:   : AutoJSAPI(FindJSContext(aGlobalObject), /* aIsMainThread = */ true)
michael@0: {
michael@0: }
michael@0: 
michael@0: AutoEntryScript::AutoEntryScript(nsIGlobalObject* aGlobalObject,
michael@0:                                  bool aIsMainThread,
michael@0:                                  JSContext* aCx)
michael@0:   : AutoJSAPI(aCx ? aCx : FindJSContext(aGlobalObject), aIsMainThread, /* aSkipNullAc = */ true)
michael@0:   , ScriptSettingsStackEntry(aGlobalObject, /* aCandidate = */ true)
michael@0:   , mAc(cx(), aGlobalObject->GetGlobalJSObject())
michael@0:   , mStack(ScriptSettingsStack::Ref())
michael@0: {
michael@0:   MOZ_ASSERT(aGlobalObject);
michael@0:   MOZ_ASSERT_IF(!aCx, aIsMainThread); // cx is mandatory off-main-thread.
michael@0:   MOZ_ASSERT_IF(aCx && aIsMainThread, aCx == FindJSContext(aGlobalObject));
michael@0:   mStack.Push(this);
michael@0: }
michael@0: 
michael@0: AutoEntryScript::~AutoEntryScript()
michael@0: {
michael@0:   MOZ_ASSERT(mStack.Incumbent() == this);
michael@0:   mStack.Pop();
michael@0: }
michael@0: 
michael@0: AutoIncumbentScript::AutoIncumbentScript(nsIGlobalObject* aGlobalObject)
michael@0:   : ScriptSettingsStackEntry(aGlobalObject, /* aCandidate = */ false)
michael@0:   , mStack(ScriptSettingsStack::Ref())
michael@0:   , mCallerOverride(nsContentUtils::GetCurrentJSContextForThread())
michael@0: {
michael@0:   mStack.Push(this);
michael@0: }
michael@0: 
michael@0: AutoIncumbentScript::~AutoIncumbentScript()
michael@0: {
michael@0:   MOZ_ASSERT(mStack.Incumbent() == this);
michael@0:   mStack.Pop();
michael@0: }
michael@0: 
michael@0: AutoNoJSAPI::AutoNoJSAPI(bool aIsMainThread)
michael@0:   : mStack(ScriptSettingsStack::Ref())
michael@0: {
michael@0:   MOZ_ASSERT_IF(nsContentUtils::GetCurrentJSContextForThread(),
michael@0:                 !JS_IsExceptionPending(nsContentUtils::GetCurrentJSContextForThread()));
michael@0:   if (aIsMainThread) {
michael@0:     mCxPusher.construct(static_cast<JSContext*>(nullptr),
michael@0:                         /* aAllowNull = */ true);
michael@0:   }
michael@0:   mStack.PushNoJSAPI();
michael@0: }
michael@0: 
michael@0: AutoNoJSAPI::~AutoNoJSAPI()
michael@0: {
michael@0:   mStack.Pop();
michael@0: }
michael@0: 
michael@0: } // namespace dom
michael@0: } // namespace mozilla