105 lines
3.5 KiB
C++
105 lines
3.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* vim: set ts=8 sts=2 et sw=2 tw=80:
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* Window and WindowProxy.
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*
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* For silly obscure reasons embedders are better off not knowing, the web wants
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* every global object to exist as two linked components: a Window component
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* that stores global variables and appears in environment chains but can't be
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* directly referred to by any script, and a WindowProxy component that
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* intermediates access to its Window that *can* be directly referred to by
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* script. (Thus the global |window| and |globalThis| properties, |this| in
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* global code, the value of |(function() { return this; })()| in non-strict
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* mode code, and similar values are WindowProxy objects, not Windows.)
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*
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* Maintaining an invariant of never exposing a Window to script requires
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* substituting in its WindowProxy in a variety of apparently arbitrary (but
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* actually *very* carefully and nervously selected) places throughout the
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* engine and indeed the universe.
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*
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* This header defines functions that let embeddings convert from a WindowProxy
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* to its Window and vice versa.
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*
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* If you're not embedding SpiderMonkey in a web browser, you can almost
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* certainly ignore this header.
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*/
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#ifndef js_friend_WindowProxy_h
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#define js_friend_WindowProxy_h
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#include "jstypes.h" // JS_PUBLIC_API
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#include "js/Class.h" // JSCLASS_IS_GLOBAL
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#include "js/Object.h" // JS::GetClass
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#include "js/RootingAPI.h" // JS::Handle
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struct JS_PUBLIC_API JSContext;
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class JS_PUBLIC_API JSObject;
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namespace js {
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/**
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* Tell the JS engine which Class is used for WindowProxy objects. Used by the
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* functions below.
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*/
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extern JS_PUBLIC_API void SetWindowProxyClass(JSContext* cx,
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const JSClass* clasp);
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/**
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* Associates a WindowProxy with a Window (global object). `windowProxy` must
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* have the Class set by SetWindowProxyClass.
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*/
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extern JS_PUBLIC_API void SetWindowProxy(JSContext* cx,
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JS::Handle<JSObject*> global,
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JS::Handle<JSObject*> windowProxy);
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namespace detail {
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extern JS_PUBLIC_API bool IsWindowSlow(JSObject* obj);
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extern JS_PUBLIC_API JSObject* ToWindowProxyIfWindowSlow(JSObject* obj);
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} // namespace detail
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/**
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* Returns true iff `obj` is a global object with an associated WindowProxy,
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* see SetWindowProxy.
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*/
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inline bool IsWindow(JSObject* obj) {
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if (JS::GetClass(obj)->flags & JSCLASS_IS_GLOBAL) {
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return detail::IsWindowSlow(obj);
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}
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return false;
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}
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/**
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* Returns true iff `obj` has the WindowProxy Class (see SetWindowProxyClass).
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*/
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extern JS_PUBLIC_API bool IsWindowProxy(JSObject* obj);
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/**
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* If `obj` is a Window, get its associated WindowProxy (or a CCW or dead
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* wrapper if the page was navigated away from), else return `obj`. This
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* function is infallible and never returns nullptr.
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*/
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MOZ_ALWAYS_INLINE JSObject* ToWindowProxyIfWindow(JSObject* obj) {
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if (JS::GetClass(obj)->flags & JSCLASS_IS_GLOBAL) {
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return detail::ToWindowProxyIfWindowSlow(obj);
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}
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return obj;
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}
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/**
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* If `obj` is a WindowProxy, get its associated Window (the compartment's
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* global), else return `obj`. This function is infallible and never returns
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* nullptr.
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*/
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extern JS_PUBLIC_API JSObject* ToWindowIfWindowProxy(JSObject* obj);
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} // namespace js
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#endif // js_friend_WindowProxy_h
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