gecko-dev/dom/bindings/CallbackObject.cpp

259 lines
8.8 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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/CallbackObject.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/DOMError.h"
#include "mozilla/dom/DOMErrorBinding.h"
#include "jsfriendapi.h"
#include "nsIScriptGlobalObject.h"
#include "nsIXPConnect.h"
#include "nsIScriptContext.h"
#include "nsPIDOMWindow.h"
#include "nsJSUtils.h"
#include "nsCxPusher.h"
#include "nsIScriptSecurityManager.h"
#include "xpcprivate.h"
#include "WorkerPrivate.h"
namespace mozilla {
namespace dom {
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(CallbackObject)
NS_INTERFACE_MAP_ENTRY(mozilla::dom::CallbackObject)
NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END
NS_IMPL_CYCLE_COLLECTING_ADDREF(CallbackObject)
NS_IMPL_CYCLE_COLLECTING_RELEASE(CallbackObject)
NS_IMPL_CYCLE_COLLECTION_CLASS(CallbackObject)
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(CallbackObject)
tmp->DropCallback();
NS_IMPL_CYCLE_COLLECTION_UNLINK_END
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(CallbackObject)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(CallbackObject)
NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mCallback)
NS_IMPL_CYCLE_COLLECTION_TRACE_END
CallbackObject::CallSetup::CallSetup(JS::Handle<JSObject*> aCallback,
ErrorResult& aRv,
ExceptionHandling aExceptionHandling,
JSCompartment* aCompartment)
: mCx(nullptr)
, mCompartment(aCompartment)
, mErrorResult(aRv)
, mExceptionHandling(aExceptionHandling)
, mIsMainThread(NS_IsMainThread())
{
if (mIsMainThread) {
nsContentUtils::EnterMicroTask();
}
// We need to produce a useful JSContext here. Ideally one that the callback
// is in some sense associated with, so that we can sort of treat it as a
// "script entry point". Though once we actually have script entry points,
// we'll need to do the script entry point bits once we have an actual
// callable.
// First, find the real underlying callback.
JSObject* realCallback = js::UncheckedUnwrap(aCallback);
JSContext* cx = nullptr;
if (mIsMainThread) {
// Now get the nsIScriptGlobalObject for this callback.
nsIScriptContext* ctx = nullptr;
nsIScriptGlobalObject* sgo = nsJSUtils::GetStaticScriptGlobal(realCallback);
if (sgo) {
// Make sure that if this is a window it's the current inner, since the
// nsIScriptContext and hence JSContext are associated with the outer
// window. Which means that if someone holds on to a function from a
// now-unloaded document we'd have the new document as the script entry
// point...
nsCOMPtr<nsPIDOMWindow> win = do_QueryInterface(sgo);
if (win) {
MOZ_ASSERT(win->IsInnerWindow());
nsPIDOMWindow* outer = win->GetOuterWindow();
if (!outer || win != outer->GetCurrentInnerWindow()) {
// Just bail out from here
return;
}
}
// if not a window at all, just press on
ctx = sgo->GetContext();
if (ctx) {
// We don't check whether scripts are enabled on ctx, because
// CheckFunctionAccess will do that anyway... and because we ignore them
// being disabled if the callee is system.
cx = ctx->GetNativeContext();
}
}
if (!cx) {
// We didn't manage to hunt down a script global to work with. Just fall
// back on using the safe context.
cx = nsContentUtils::GetSafeJSContext();
}
// Make sure our JSContext is pushed on the stack.
mCxPusher.Push(cx);
} else {
cx = workers::GetCurrentThreadJSContext();
}
// Unmark the callable, and stick it in a Rooted before it can go gray again.
// Nothing before us in this function can trigger a CC, so it's safe to wait
// until here it do the unmark. This allows us to order the following two
// operations _after_ the Push() above, which lets us take advantage of the
// JSAutoRequest embedded in the pusher.
//
// We can do this even though we're not in the right compartment yet, because
// Rooted<> does not care about compartments.
JS::ExposeObjectToActiveJS(aCallback);
mRootedCallable.construct(cx, aCallback);
if (mIsMainThread) {
// Check that it's ok to run this callback at all.
// FIXME: Bug 807371: we want a less silly check here.
// Make sure to unwrap aCallback before passing it in, because
// getting principals from wrappers is silly.
nsresult rv = nsContentUtils::GetSecurityManager()->
CheckFunctionAccess(cx, js::UncheckedUnwrap(aCallback), nullptr);
if (NS_FAILED(rv)) {
// Security check failed. We're done here.
return;
}
}
// Enter the compartment of our callback, so we can actually work with it.
mAc.construct(cx, aCallback);
// And now we're ready to go.
mCx = cx;
// Make sure the JS engine doesn't report exceptions we want to re-throw
if (mExceptionHandling == eRethrowContentExceptions ||
mExceptionHandling == eRethrowExceptions) {
mSavedJSContextOptions = JS_GetOptions(cx);
JS_SetOptions(cx, mSavedJSContextOptions | JSOPTION_DONT_REPORT_UNCAUGHT);
}
}
bool
CallbackObject::CallSetup::ShouldRethrowException(JS::Handle<JS::Value> aException)
{
if (mExceptionHandling == eRethrowExceptions) {
return true;
}
MOZ_ASSERT(mExceptionHandling == eRethrowContentExceptions);
// For eRethrowContentExceptions we only want to throw an exception if the
// object that was thrown is a DOMError object in the caller compartment
// (which we stored in mCompartment).
if (!aException.isObject()) {
return false;
}
JS::Rooted<JSObject*> obj(mCx, &aException.toObject());
obj = js::UncheckedUnwrap(obj, /* stopAtOuter = */ false);
if (js::GetObjectCompartment(obj) != mCompartment) {
return false;
}
DOMError* domError;
return NS_SUCCEEDED(UNWRAP_OBJECT(DOMError, mCx, obj, domError));
}
CallbackObject::CallSetup::~CallSetup()
{
// First things first: if we have a JSContext, report any pending
// errors on it, unless we were told to re-throw them.
if (mCx) {
bool dealtWithPendingException = false;
if (mExceptionHandling == eRethrowContentExceptions ||
mExceptionHandling == eRethrowExceptions) {
// Restore the old context options
JS_SetOptions(mCx, mSavedJSContextOptions);
mErrorResult.MightThrowJSException();
if (JS_IsExceptionPending(mCx)) {
JS::Rooted<JS::Value> exn(mCx);
if (JS_GetPendingException(mCx, &exn) &&
ShouldRethrowException(exn)) {
mErrorResult.ThrowJSException(mCx, exn);
JS_ClearPendingException(mCx);
dealtWithPendingException = true;
}
}
}
if (!dealtWithPendingException) {
// Either we're supposed to report our exceptions, or we're supposed to
// re-throw them but we failed to JS_GetPendingException. Either way,
// just report the pending exception, if any.
nsJSUtils::ReportPendingException(mCx);
}
}
// To get our nesting right we have to destroy our JSAutoCompartment first.
// But be careful: it might not have been constructed at all!
mAc.destroyIfConstructed();
// XXXbz For that matter why do we need to manually call ScriptEvaluated at
// all? nsCxPusher::Pop will do that nowadays if !mScriptIsRunning, so the
// concerns from bug 295983 don't seem relevant anymore. Do we want to make
// sure it's still called when !mScriptIsRunning? I guess play it safe for
// now and do what CallEventHandler did, which is call always.
// Popping an nsCxPusher is safe even if it never got pushed.
mCxPusher.Pop();
// It is important that this is the last thing we do, after leaving the
// compartment and popping the context.
if (mIsMainThread) {
nsContentUtils::LeaveMicroTask();
}
}
already_AddRefed<nsISupports>
CallbackObjectHolderBase::ToXPCOMCallback(CallbackObject* aCallback,
const nsIID& aIID) const
{
MOZ_ASSERT(NS_IsMainThread());
if (!aCallback) {
return nullptr;
}
AutoSafeJSContext cx;
JS::Rooted<JSObject*> callback(cx, aCallback->Callback());
JSAutoCompartment ac(cx, callback);
nsRefPtr<nsXPCWrappedJS> wrappedJS;
nsresult rv =
nsXPCWrappedJS::GetNewOrUsed(callback, aIID,
nullptr, getter_AddRefs(wrappedJS));
if (NS_FAILED(rv) || !wrappedJS) {
return nullptr;
}
nsCOMPtr<nsISupports> retval;
rv = wrappedJS->QueryInterface(aIID, getter_AddRefs(retval));
if (NS_FAILED(rv)) {
return nullptr;
}
return retval.forget();
}
} // namespace dom
} // namespace mozilla