gecko/dom/base/ScriptSettings.cpp

192 lines
5.3 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim: ft=cpp tw=78 sw=2 et ts=2
/* 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 "mozilla/dom/ScriptSettings.h"
#include "mozilla/ThreadLocal.h"
#include "mozilla/Assertions.h"
#include "jsapi.h"
#include "xpcpublic.h"
#include "nsIGlobalObject.h"
#include "nsIScriptGlobalObject.h"
#include "nsIScriptContext.h"
#include "nsContentUtils.h"
#include "nsTArray.h"
namespace mozilla {
namespace dom {
class ScriptSettingsStack;
static mozilla::ThreadLocal<ScriptSettingsStack*> sScriptSettingsTLS;
ScriptSettingsStackEntry ScriptSettingsStackEntry::SystemSingleton;
class ScriptSettingsStack {
public:
static ScriptSettingsStack& Ref() {
return *sScriptSettingsTLS.get();
}
ScriptSettingsStack() {};
void Push(ScriptSettingsStackEntry* aSettings) {
// The bottom-most entry must always be a candidate entry point.
MOZ_ASSERT_IF(mStack.Length() == 0 || mStack.LastElement()->IsSystemSingleton(),
aSettings->mIsCandidateEntryPoint);
mStack.AppendElement(aSettings);
}
void PushSystem() {
mStack.AppendElement(&ScriptSettingsStackEntry::SystemSingleton);
}
void Pop() {
MOZ_ASSERT(mStack.Length() > 0);
mStack.RemoveElementAt(mStack.Length() - 1);
}
nsIGlobalObject* Incumbent() {
if (!mStack.Length()) {
return nullptr;
}
return mStack.LastElement()->mGlobalObject;
}
nsIGlobalObject* EntryPoint() {
if (!mStack.Length())
return nullptr;
for (int i = mStack.Length() - 1; i >= 0; --i) {
if (mStack[i]->mIsCandidateEntryPoint) {
return mStack[i]->mGlobalObject;
}
}
MOZ_ASSUME_UNREACHABLE("Non-empty stack should always have an entry point");
}
private:
// These pointers are caller-owned.
nsTArray<ScriptSettingsStackEntry*> mStack;
};
void
InitScriptSettings()
{
if (!sScriptSettingsTLS.initialized()) {
bool success = sScriptSettingsTLS.init();
if (!success) {
MOZ_CRASH();
}
}
ScriptSettingsStack* ptr = new ScriptSettingsStack();
sScriptSettingsTLS.set(ptr);
}
void DestroyScriptSettings()
{
ScriptSettingsStack* ptr = sScriptSettingsTLS.get();
MOZ_ASSERT(ptr);
sScriptSettingsTLS.set(nullptr);
delete ptr;
}
// Note: When we're ready to expose it, GetEntryGlobal will look similar to
// GetIncumbentGlobal below.
nsIGlobalObject*
GetIncumbentGlobal()
{
// We need the current JSContext in order to check the JS for
// scripted frames that may have appeared since anyone last
// manipulated the stack. If it's null, that means that there
// must be no entry point on the stack, and therefore no incumbent
// global either.
JSContext *cx = nsContentUtils::GetCurrentJSContextForThread();
if (!cx) {
MOZ_ASSERT(ScriptSettingsStack::Ref().EntryPoint() == nullptr);
return nullptr;
}
// See what the JS engine has to say. If we've got a scripted caller
// override in place, the JS engine will lie to us and pretend that
// there's nothing on the JS stack, which will cause us to check the
// incumbent script stack below.
JS::RootedScript script(cx);
if (JS_DescribeScriptedCaller(cx, &script, nullptr)) {
JS::RootedObject global(cx, JS_GetGlobalFromScript(script));
MOZ_ASSERT(global);
return xpc::GetNativeForGlobal(global);
}
// Ok, nothing from the JS engine. Let's use whatever's on the
// explicit stack.
return ScriptSettingsStack::Ref().Incumbent();
}
AutoEntryScript::AutoEntryScript(nsIGlobalObject* aGlobalObject,
bool aIsMainThread,
JSContext* aCx)
: mStack(ScriptSettingsStack::Ref())
, mEntry(aGlobalObject, /* aCandidate = */ true)
{
MOZ_ASSERT(aGlobalObject);
if (!aCx) {
// If the caller didn't provide a cx, hunt one down. This isn't exactly
// fast, but the callers that care about performance can pass an explicit
// cx for now. Eventually, the whole cx pushing thing will go away
// entirely.
MOZ_ASSERT(aIsMainThread, "cx is mandatory off-main-thread");
nsCOMPtr<nsIScriptGlobalObject> sgo = do_QueryInterface(aGlobalObject);
if (sgo && sgo->GetScriptContext()) {
aCx = sgo->GetScriptContext()->GetNativeContext();
}
if (!aCx) {
aCx = nsContentUtils::GetSafeJSContext();
}
}
if (aIsMainThread) {
mCxPusher.Push(aCx);
}
mAc.construct(aCx, aGlobalObject->GetGlobalJSObject());
mStack.Push(&mEntry);
}
AutoEntryScript::~AutoEntryScript()
{
MOZ_ASSERT(mStack.Incumbent() == mEntry.mGlobalObject);
mStack.Pop();
}
AutoIncumbentScript::AutoIncumbentScript(nsIGlobalObject* aGlobalObject)
: mStack(ScriptSettingsStack::Ref())
, mEntry(aGlobalObject, /* aCandidate = */ false)
, mCallerOverride(nsContentUtils::GetCurrentJSContextForThread())
{
mStack.Push(&mEntry);
}
AutoIncumbentScript::~AutoIncumbentScript()
{
MOZ_ASSERT(mStack.Incumbent() == mEntry.mGlobalObject);
mStack.Pop();
}
AutoSystemCaller::AutoSystemCaller(bool aIsMainThread)
: mStack(ScriptSettingsStack::Ref())
{
if (aIsMainThread) {
mCxPusher.PushNull();
}
mStack.PushSystem();
}
AutoSystemCaller::~AutoSystemCaller()
{
mStack.Pop();
}
} // namespace dom
} // namespace mozilla