gecko-dev/dom/base/ScriptSettings.cpp

271 lines
8.1 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"
#include "nsJSUtils.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);
}
ScriptSettingsStackEntry* Incumbent() {
if (!mStack.Length()) {
return nullptr;
}
return mStack.LastElement();
}
nsIGlobalObject* IncumbentGlobal() {
ScriptSettingsStackEntry *entry = Incumbent();
return entry ? entry->mGlobalObject : nullptr;
}
ScriptSettingsStackEntry* EntryPoint() {
if (!mStack.Length())
return nullptr;
for (int i = mStack.Length() - 1; i >= 0; --i) {
if (mStack[i]->mIsCandidateEntryPoint) {
return mStack[i];
}
}
MOZ_ASSUME_UNREACHABLE("Non-empty stack should always have an entry point");
}
nsIGlobalObject* EntryGlobal() {
ScriptSettingsStackEntry *entry = EntryPoint();
return entry ? entry->mGlobalObject : nullptr;
}
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;
}
// This mostly gets the entry global, but doesn't entirely match the spec in
// certain edge cases. It's good enough for some purposes, but not others. If
// you want to call this function, ping bholley and describe your use-case.
nsIGlobalObject*
BrokenGetEntryGlobal()
{
// 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 global on the stack.
JSContext *cx = nsContentUtils::GetCurrentJSContextForThread();
if (!cx) {
MOZ_ASSERT(ScriptSettingsStack::Ref().EntryGlobal() == nullptr);
return nullptr;
}
return nsJSUtils::GetDynamicScriptGlobal(cx);
}
// 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 global on the stack, and therefore no incumbent
// global either.
JSContext *cx = nsContentUtils::GetCurrentJSContextForThread();
if (!cx) {
MOZ_ASSERT(ScriptSettingsStack::Ref().EntryGlobal() == 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.
if (JSObject *global = JS::GetScriptedCallerGlobal(cx)) {
return xpc::GetNativeForGlobal(global);
}
// Ok, nothing from the JS engine. Let's use whatever's on the
// explicit stack.
return ScriptSettingsStack::Ref().IncumbentGlobal();
}
nsIPrincipal*
GetWebIDLCallerPrincipal()
{
MOZ_ASSERT(NS_IsMainThread());
ScriptSettingsStackEntry *entry = ScriptSettingsStack::Ref().EntryPoint();
// If we have an entry point that is not the system singleton, we know it
// must be an AutoEntryScript.
if (!entry || entry->IsSystemSingleton()) {
return nullptr;
}
AutoEntryScript* aes = static_cast<AutoEntryScript*>(entry);
// We can't yet rely on the Script Settings Stack to properly determine the
// entry script, because there are still lots of places in the tree where we
// don't yet use an AutoEntryScript (bug 951991 tracks this work). In the
// mean time though, we can make some observations to hack around the
// problem:
//
// (1) All calls into JS-implemented WebIDL go through CallSetup, which goes
// through AutoEntryScript.
// (2) The top candidate entry point in the Script Settings Stack is the
// entry point if and only if no other JSContexts have been pushed on
// top of the push made by that entry's AutoEntryScript.
//
// Because of (1), all of the cases where we might return a non-null
// WebIDL Caller are guaranteed to have put an entry on the Script Settings
// Stack, so we can restrict our search to that. Moreover, (2) gives us a
// criterion to determine whether an entry in the Script Setting Stack means
// that we should return a non-null WebIDL Caller.
//
// Once we fix bug 951991, this can all be simplified.
if (!aes->mCxPusher.ref().IsStackTop()) {
return nullptr;
}
return aes->mWebIDLCallerPrincipal;
}
static JSContext*
FindJSContext(nsIGlobalObject* aGlobalObject)
{
MOZ_ASSERT(NS_IsMainThread());
JSContext *cx = nullptr;
nsCOMPtr<nsIScriptGlobalObject> sgo = do_QueryInterface(aGlobalObject);
if (sgo && sgo->GetScriptContext()) {
cx = sgo->GetScriptContext()->GetNativeContext();
}
if (!cx) {
cx = nsContentUtils::GetSafeJSContext();
}
return cx;
}
AutoEntryScript::AutoEntryScript(nsIGlobalObject* aGlobalObject,
bool aIsMainThread,
JSContext* aCx)
: ScriptSettingsStackEntry(aGlobalObject, /* aCandidate = */ true)
, mStack(ScriptSettingsStack::Ref())
, mCx(aCx)
{
MOZ_ASSERT(aGlobalObject);
MOZ_ASSERT_IF(!mCx, aIsMainThread); // cx is mandatory off-main-thread.
MOZ_ASSERT_IF(mCx && aIsMainThread, mCx == FindJSContext(aGlobalObject));
if (!mCx) {
// 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.
mCx = FindJSContext(aGlobalObject);
MOZ_ASSERT(mCx);
}
if (aIsMainThread) {
mCxPusher.construct(mCx);
}
mAc.construct(mCx, aGlobalObject->GetGlobalJSObject());
mStack.Push(this);
}
AutoEntryScript::~AutoEntryScript()
{
MOZ_ASSERT(mStack.Incumbent() == this);
mStack.Pop();
}
AutoIncumbentScript::AutoIncumbentScript(nsIGlobalObject* aGlobalObject)
: ScriptSettingsStackEntry(aGlobalObject, /* aCandidate = */ false)
, mStack(ScriptSettingsStack::Ref())
, mCallerOverride(nsContentUtils::GetCurrentJSContextForThread())
{
mStack.Push(this);
}
AutoIncumbentScript::~AutoIncumbentScript()
{
MOZ_ASSERT(mStack.Incumbent() == this);
mStack.Pop();
}
AutoSystemCaller::AutoSystemCaller(bool aIsMainThread)
: mStack(ScriptSettingsStack::Ref())
{
if (aIsMainThread) {
mCxPusher.construct(static_cast<JSContext*>(nullptr),
/* aAllowNull = */ true);
}
mStack.PushSystem();
}
AutoSystemCaller::~AutoSystemCaller()
{
mStack.Pop();
}
} // namespace dom
} // namespace mozilla