1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/dom/base/ScriptSettings.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,297 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +// vim: ft=cpp tw=78 sw=2 et ts=2
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "mozilla/dom/ScriptSettings.h"
1.11 +#include "mozilla/ThreadLocal.h"
1.12 +#include "mozilla/Assertions.h"
1.13 +
1.14 +#include "jsapi.h"
1.15 +#include "xpcpublic.h"
1.16 +#include "nsIGlobalObject.h"
1.17 +#include "nsIScriptGlobalObject.h"
1.18 +#include "nsIScriptContext.h"
1.19 +#include "nsContentUtils.h"
1.20 +#include "nsTArray.h"
1.21 +#include "nsJSUtils.h"
1.22 +
1.23 +namespace mozilla {
1.24 +namespace dom {
1.25 +
1.26 +class ScriptSettingsStack;
1.27 +static mozilla::ThreadLocal<ScriptSettingsStack*> sScriptSettingsTLS;
1.28 +
1.29 +ScriptSettingsStackEntry ScriptSettingsStackEntry::NoJSAPISingleton;
1.30 +
1.31 +class ScriptSettingsStack {
1.32 +public:
1.33 + static ScriptSettingsStack& Ref() {
1.34 + return *sScriptSettingsTLS.get();
1.35 + }
1.36 + ScriptSettingsStack() {};
1.37 +
1.38 + void Push(ScriptSettingsStackEntry* aSettings) {
1.39 + // The bottom-most entry must always be a candidate entry point.
1.40 + MOZ_ASSERT_IF(mStack.Length() == 0 || mStack.LastElement()->NoJSAPI(),
1.41 + aSettings->mIsCandidateEntryPoint);
1.42 + mStack.AppendElement(aSettings);
1.43 + }
1.44 +
1.45 + void PushNoJSAPI() {
1.46 + mStack.AppendElement(&ScriptSettingsStackEntry::NoJSAPISingleton);
1.47 + }
1.48 +
1.49 + void Pop() {
1.50 + MOZ_ASSERT(mStack.Length() > 0);
1.51 + mStack.RemoveElementAt(mStack.Length() - 1);
1.52 + }
1.53 +
1.54 + ScriptSettingsStackEntry* Incumbent() {
1.55 + if (!mStack.Length()) {
1.56 + return nullptr;
1.57 + }
1.58 + return mStack.LastElement();
1.59 + }
1.60 +
1.61 + nsIGlobalObject* IncumbentGlobal() {
1.62 + ScriptSettingsStackEntry *entry = Incumbent();
1.63 + return entry ? entry->mGlobalObject : nullptr;
1.64 + }
1.65 +
1.66 + ScriptSettingsStackEntry* EntryPoint() {
1.67 + if (!mStack.Length())
1.68 + return nullptr;
1.69 + for (int i = mStack.Length() - 1; i >= 0; --i) {
1.70 + if (mStack[i]->mIsCandidateEntryPoint) {
1.71 + return mStack[i];
1.72 + }
1.73 + }
1.74 + MOZ_ASSUME_UNREACHABLE("Non-empty stack should always have an entry point");
1.75 + }
1.76 +
1.77 + nsIGlobalObject* EntryGlobal() {
1.78 + ScriptSettingsStackEntry *entry = EntryPoint();
1.79 + return entry ? entry->mGlobalObject : nullptr;
1.80 + }
1.81 +
1.82 +private:
1.83 + // These pointers are caller-owned.
1.84 + nsTArray<ScriptSettingsStackEntry*> mStack;
1.85 +};
1.86 +
1.87 +void
1.88 +InitScriptSettings()
1.89 +{
1.90 + if (!sScriptSettingsTLS.initialized()) {
1.91 + bool success = sScriptSettingsTLS.init();
1.92 + if (!success) {
1.93 + MOZ_CRASH();
1.94 + }
1.95 + }
1.96 +
1.97 + ScriptSettingsStack* ptr = new ScriptSettingsStack();
1.98 + sScriptSettingsTLS.set(ptr);
1.99 +}
1.100 +
1.101 +void DestroyScriptSettings()
1.102 +{
1.103 + ScriptSettingsStack* ptr = sScriptSettingsTLS.get();
1.104 + MOZ_ASSERT(ptr);
1.105 + sScriptSettingsTLS.set(nullptr);
1.106 + delete ptr;
1.107 +}
1.108 +
1.109 +// This mostly gets the entry global, but doesn't entirely match the spec in
1.110 +// certain edge cases. It's good enough for some purposes, but not others. If
1.111 +// you want to call this function, ping bholley and describe your use-case.
1.112 +nsIGlobalObject*
1.113 +BrokenGetEntryGlobal()
1.114 +{
1.115 + // We need the current JSContext in order to check the JS for
1.116 + // scripted frames that may have appeared since anyone last
1.117 + // manipulated the stack. If it's null, that means that there
1.118 + // must be no entry global on the stack.
1.119 + JSContext *cx = nsContentUtils::GetCurrentJSContextForThread();
1.120 + if (!cx) {
1.121 + MOZ_ASSERT(ScriptSettingsStack::Ref().EntryGlobal() == nullptr);
1.122 + return nullptr;
1.123 + }
1.124 +
1.125 + return nsJSUtils::GetDynamicScriptGlobal(cx);
1.126 +}
1.127 +
1.128 +// Note: When we're ready to expose it, GetEntryGlobal will look similar to
1.129 +// GetIncumbentGlobal below.
1.130 +
1.131 +nsIGlobalObject*
1.132 +GetIncumbentGlobal()
1.133 +{
1.134 + // We need the current JSContext in order to check the JS for
1.135 + // scripted frames that may have appeared since anyone last
1.136 + // manipulated the stack. If it's null, that means that there
1.137 + // must be no entry global on the stack, and therefore no incumbent
1.138 + // global either.
1.139 + JSContext *cx = nsContentUtils::GetCurrentJSContextForThread();
1.140 + if (!cx) {
1.141 + MOZ_ASSERT(ScriptSettingsStack::Ref().EntryGlobal() == nullptr);
1.142 + return nullptr;
1.143 + }
1.144 +
1.145 + // See what the JS engine has to say. If we've got a scripted caller
1.146 + // override in place, the JS engine will lie to us and pretend that
1.147 + // there's nothing on the JS stack, which will cause us to check the
1.148 + // incumbent script stack below.
1.149 + if (JSObject *global = JS::GetScriptedCallerGlobal(cx)) {
1.150 + return xpc::GetNativeForGlobal(global);
1.151 + }
1.152 +
1.153 + // Ok, nothing from the JS engine. Let's use whatever's on the
1.154 + // explicit stack.
1.155 + return ScriptSettingsStack::Ref().IncumbentGlobal();
1.156 +}
1.157 +
1.158 +nsIPrincipal*
1.159 +GetWebIDLCallerPrincipal()
1.160 +{
1.161 + MOZ_ASSERT(NS_IsMainThread());
1.162 + ScriptSettingsStackEntry *entry = ScriptSettingsStack::Ref().EntryPoint();
1.163 +
1.164 + // If we have an entry point that is not the NoJSAPI singleton, we know it
1.165 + // must be an AutoEntryScript.
1.166 + if (!entry || entry->NoJSAPI()) {
1.167 + return nullptr;
1.168 + }
1.169 + AutoEntryScript* aes = static_cast<AutoEntryScript*>(entry);
1.170 +
1.171 + // We can't yet rely on the Script Settings Stack to properly determine the
1.172 + // entry script, because there are still lots of places in the tree where we
1.173 + // don't yet use an AutoEntryScript (bug 951991 tracks this work). In the
1.174 + // mean time though, we can make some observations to hack around the
1.175 + // problem:
1.176 + //
1.177 + // (1) All calls into JS-implemented WebIDL go through CallSetup, which goes
1.178 + // through AutoEntryScript.
1.179 + // (2) The top candidate entry point in the Script Settings Stack is the
1.180 + // entry point if and only if no other JSContexts have been pushed on
1.181 + // top of the push made by that entry's AutoEntryScript.
1.182 + //
1.183 + // Because of (1), all of the cases where we might return a non-null
1.184 + // WebIDL Caller are guaranteed to have put an entry on the Script Settings
1.185 + // Stack, so we can restrict our search to that. Moreover, (2) gives us a
1.186 + // criterion to determine whether an entry in the Script Setting Stack means
1.187 + // that we should return a non-null WebIDL Caller.
1.188 + //
1.189 + // Once we fix bug 951991, this can all be simplified.
1.190 + if (!aes->CxPusherIsStackTop()) {
1.191 + return nullptr;
1.192 + }
1.193 +
1.194 + return aes->mWebIDLCallerPrincipal;
1.195 +}
1.196 +
1.197 +static JSContext*
1.198 +FindJSContext(nsIGlobalObject* aGlobalObject)
1.199 +{
1.200 + MOZ_ASSERT(NS_IsMainThread());
1.201 + JSContext *cx = nullptr;
1.202 + nsCOMPtr<nsIScriptGlobalObject> sgo = do_QueryInterface(aGlobalObject);
1.203 + if (sgo && sgo->GetScriptContext()) {
1.204 + cx = sgo->GetScriptContext()->GetNativeContext();
1.205 + }
1.206 + if (!cx) {
1.207 + cx = nsContentUtils::GetSafeJSContext();
1.208 + }
1.209 + return cx;
1.210 +}
1.211 +
1.212 +AutoJSAPI::AutoJSAPI()
1.213 + : mCx(nsContentUtils::GetDefaultJSContextForThread())
1.214 +{
1.215 + if (NS_IsMainThread()) {
1.216 + mCxPusher.construct(mCx);
1.217 + }
1.218 +
1.219 + // Leave the cx in a null compartment.
1.220 + mNullAc.construct(mCx);
1.221 +}
1.222 +
1.223 +AutoJSAPI::AutoJSAPI(JSContext *aCx, bool aIsMainThread, bool aSkipNullAc)
1.224 + : mCx(aCx)
1.225 +{
1.226 + MOZ_ASSERT_IF(aIsMainThread, NS_IsMainThread());
1.227 + if (aIsMainThread) {
1.228 + mCxPusher.construct(mCx);
1.229 + }
1.230 +
1.231 + // In general we want to leave the cx in a null compartment, but we let
1.232 + // subclasses skip this if they plan to immediately enter a compartment.
1.233 + if (!aSkipNullAc) {
1.234 + mNullAc.construct(mCx);
1.235 + }
1.236 +}
1.237 +
1.238 +AutoJSAPIWithErrorsReportedToWindow::AutoJSAPIWithErrorsReportedToWindow(nsIScriptContext* aScx)
1.239 + : AutoJSAPI(aScx->GetNativeContext(), /* aIsMainThread = */ true)
1.240 +{
1.241 +}
1.242 +
1.243 +AutoJSAPIWithErrorsReportedToWindow::AutoJSAPIWithErrorsReportedToWindow(nsIGlobalObject* aGlobalObject)
1.244 + : AutoJSAPI(FindJSContext(aGlobalObject), /* aIsMainThread = */ true)
1.245 +{
1.246 +}
1.247 +
1.248 +AutoEntryScript::AutoEntryScript(nsIGlobalObject* aGlobalObject,
1.249 + bool aIsMainThread,
1.250 + JSContext* aCx)
1.251 + : AutoJSAPI(aCx ? aCx : FindJSContext(aGlobalObject), aIsMainThread, /* aSkipNullAc = */ true)
1.252 + , ScriptSettingsStackEntry(aGlobalObject, /* aCandidate = */ true)
1.253 + , mAc(cx(), aGlobalObject->GetGlobalJSObject())
1.254 + , mStack(ScriptSettingsStack::Ref())
1.255 +{
1.256 + MOZ_ASSERT(aGlobalObject);
1.257 + MOZ_ASSERT_IF(!aCx, aIsMainThread); // cx is mandatory off-main-thread.
1.258 + MOZ_ASSERT_IF(aCx && aIsMainThread, aCx == FindJSContext(aGlobalObject));
1.259 + mStack.Push(this);
1.260 +}
1.261 +
1.262 +AutoEntryScript::~AutoEntryScript()
1.263 +{
1.264 + MOZ_ASSERT(mStack.Incumbent() == this);
1.265 + mStack.Pop();
1.266 +}
1.267 +
1.268 +AutoIncumbentScript::AutoIncumbentScript(nsIGlobalObject* aGlobalObject)
1.269 + : ScriptSettingsStackEntry(aGlobalObject, /* aCandidate = */ false)
1.270 + , mStack(ScriptSettingsStack::Ref())
1.271 + , mCallerOverride(nsContentUtils::GetCurrentJSContextForThread())
1.272 +{
1.273 + mStack.Push(this);
1.274 +}
1.275 +
1.276 +AutoIncumbentScript::~AutoIncumbentScript()
1.277 +{
1.278 + MOZ_ASSERT(mStack.Incumbent() == this);
1.279 + mStack.Pop();
1.280 +}
1.281 +
1.282 +AutoNoJSAPI::AutoNoJSAPI(bool aIsMainThread)
1.283 + : mStack(ScriptSettingsStack::Ref())
1.284 +{
1.285 + MOZ_ASSERT_IF(nsContentUtils::GetCurrentJSContextForThread(),
1.286 + !JS_IsExceptionPending(nsContentUtils::GetCurrentJSContextForThread()));
1.287 + if (aIsMainThread) {
1.288 + mCxPusher.construct(static_cast<JSContext*>(nullptr),
1.289 + /* aAllowNull = */ true);
1.290 + }
1.291 + mStack.PushNoJSAPI();
1.292 +}
1.293 +
1.294 +AutoNoJSAPI::~AutoNoJSAPI()
1.295 +{
1.296 + mStack.Pop();
1.297 +}
1.298 +
1.299 +} // namespace dom
1.300 +} // namespace mozilla
