gecko-dev/dom/bindings/CallbackFunction.cpp

157 lines
5.4 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/CallbackFunction.h"
#include "jsfriendapi.h"
#include "nsIScriptGlobalObject.h"
#include "nsIXPConnect.h"
#include "nsIScriptContext.h"
#include "nsPIDOMWindow.h"
#include "nsJSUtils.h"
#include "nsIScriptSecurityManager.h"
namespace mozilla {
namespace dom {
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(CallbackFunction)
NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END
NS_IMPL_CYCLE_COLLECTING_ADDREF(CallbackFunction)
NS_IMPL_CYCLE_COLLECTING_RELEASE(CallbackFunction)
NS_IMPL_CYCLE_COLLECTION_CLASS(CallbackFunction)
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(CallbackFunction)
tmp->DropCallback();
NS_IMPL_CYCLE_COLLECTION_UNLINK_END
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(CallbackFunction)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(CallbackFunction)
NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mCallable)
NS_IMPL_CYCLE_COLLECTION_TRACE_END
CallbackFunction::CallSetup::CallSetup(JSObject* const aCallable)
: mCx(nullptr)
{
xpc_UnmarkGrayObject(aCallable);
// We need to produce a useful JSContext here. Ideally one that the callable
// is in some sense associated with, so that we can sort of treat it as a
// "script entry point".
// First, find the real underlying callable.
JSObject* realCallable = js::UnwrapObject(aCallable);
// Now get the nsIScriptGlobalObject for this callable.
JSContext* cx = nullptr;
nsIScriptContext* ctx = nullptr;
nsIScriptGlobalObject* sgo = nsJSUtils::GetStaticScriptGlobal(realCallable);
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();
}
// Victory! We have a JSContext. Now do the things we need a JSContext for.
mAr.construct(cx);
// Make sure our JSContext is pushed on the stack.
if (!mCxPusher.Push(cx, false)) {
return;
}
// After this point we guarantee calling ScriptEvaluated() if we
// have an nsIScriptContext.
// XXXbz Why, if, say CheckFunctionAccess fails? I know that's how
// nsJSContext::CallEventHandler works, but is it required?
// FIXME: Bug 807369.
mCtx = ctx;
// 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 aCallable before passing it in, because
// getting principals from wrappers is silly.
nsresult rv = nsContentUtils::GetSecurityManager()->
CheckFunctionAccess(cx, js::UnwrapObject(aCallable), nullptr);
// Construct a termination func holder even if we're not planning to
// run any script. We need this because we're going to call
// ScriptEvaluated even if we don't run the script... See XXX
// comment above.
if (ctx) {
mTerminationFuncHolder.construct(static_cast<nsJSContext*>(ctx));
}
if (NS_FAILED(rv)) {
// Security check failed. We're done here.
return;
}
// Enter the compartment of our callable, so we can actually call it.
mAc.construct(cx, aCallable);
// And now we're ready to go.
mCx = cx;
}
CallbackFunction::CallSetup::~CallSetup()
{
// First things first: if we have a JSContext, report any pending
// errors on it.
if (mCx) {
nsJSUtils::ReportPendingException(mCx);
}
// If we have an mCtx, we need to call ScriptEvaluated() on it. But we have
// to do that after we pop the JSContext stack (see bug 295983). And 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();
if (mCtx) {
mCtx->ScriptEvaluated(true);
}
}
} // namespace dom
} // namespace mozilla