/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=8 sts=2 et sw=2 tw=80: */ /* 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/. */ #ifndef mozilla_dom_DOMJSProxyHandler_h #define mozilla_dom_DOMJSProxyHandler_h #include "mozilla/Attributes.h" #include "mozilla/Likely.h" #include "jsapi.h" #include "js/Proxy.h" #include "nsString.h" namespace mozilla { namespace dom { /** * DOM proxies store the expando object in the private slot. * * The expando object is a plain JSObject whose properties correspond to * "expandos" (custom properties set by the script author). * * The exact value stored in the proxy's private slot depends on whether the * interface is annotated with the [OverrideBuiltins] extended attribute. * * If it is, the proxy is initialized with a PrivateValue, which contains a * pointer to a js::ExpandoAndGeneration object; this contains a pointer to * the actual expando object as well as the "generation" of the object. The * proxy handler will trace the expando object stored in the * js::ExpandoAndGeneration while the proxy itself is alive. * * If it is not, the proxy is initialized with an UndefinedValue. In * EnsureExpandoObject, it is set to an ObjectValue that points to the * expando object directly. (It is set back to an UndefinedValue only when * the object is about to die.) */ template struct Prefable; class BaseDOMProxyHandler : public js::BaseProxyHandler { public: explicit constexpr BaseDOMProxyHandler(const void* aProxyFamily, bool aHasPrototype = false) : js::BaseProxyHandler(aProxyFamily, aHasPrototype) {} // Implementations of methods that can be implemented in terms of // other lower-level methods. bool getOwnPropertyDescriptor(JSContext* cx, JS::Handle proxy, JS::Handle id, JS::MutableHandle desc) const override; virtual bool ownPropertyKeys(JSContext* cx, JS::Handle proxy, JS::AutoIdVector &props) const override; virtual bool getPrototypeIfOrdinary(JSContext* cx, JS::Handle proxy, bool* isOrdinary, JS::MutableHandle proto) const override; // We override getOwnEnumerablePropertyKeys() and implement it directly // instead of using the default implementation, which would call // ownPropertyKeys and then filter out the non-enumerable ones. This avoids // unnecessary work during enumeration. virtual bool getOwnEnumerablePropertyKeys(JSContext* cx, JS::Handle proxy, JS::AutoIdVector &props) const override; bool watch(JSContext* cx, JS::Handle proxy, JS::Handle id, JS::Handle callable) const override; bool unwatch(JSContext* cx, JS::Handle proxy, JS::Handle id) const override; protected: // Hook for subclasses to implement shared ownPropertyKeys()/keys() // functionality. The "flags" argument is either JSITER_OWNONLY (for keys()) // or JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS (for // ownPropertyKeys()). virtual bool ownPropNames(JSContext* cx, JS::Handle proxy, unsigned flags, JS::AutoIdVector& props) const = 0; // Hook for subclasses to allow set() to ignore named props while other things // that look at property descriptors see them. This is intentionally not // named getOwnPropertyDescriptor to avoid subclasses that override it hiding // our public getOwnPropertyDescriptor. virtual bool getOwnPropDescriptor(JSContext* cx, JS::Handle proxy, JS::Handle id, bool ignoreNamedProps, JS::MutableHandle desc) const = 0; }; class DOMProxyHandler : public BaseDOMProxyHandler { public: constexpr DOMProxyHandler() : BaseDOMProxyHandler(&family) {} bool defineProperty(JSContext* cx, JS::Handle proxy, JS::Handle id, JS::Handle desc, JS::ObjectOpResult &result) const override { bool unused; return defineProperty(cx, proxy, id, desc, result, &unused); } virtual bool defineProperty(JSContext* cx, JS::Handle proxy, JS::Handle id, JS::Handle desc, JS::ObjectOpResult &result, bool *defined) const; bool delete_(JSContext* cx, JS::Handle proxy, JS::Handle id, JS::ObjectOpResult &result) const override; bool preventExtensions(JSContext* cx, JS::Handle proxy, JS::ObjectOpResult& result) const override; bool isExtensible(JSContext *cx, JS::Handle proxy, bool *extensible) const override; bool set(JSContext *cx, JS::Handle proxy, JS::Handle id, JS::Handle v, JS::Handle receiver, JS::ObjectOpResult &result) const override; /* * If assigning to proxy[id] hits a named setter with OverrideBuiltins or * an indexed setter, call it and set *done to true on success. Otherwise, set * *done to false. */ virtual bool setCustom(JSContext* cx, JS::Handle proxy, JS::Handle id, JS::Handle v, bool *done) const; /* * Get the expando object for the given DOM proxy. */ static JSObject* GetExpandoObject(JSObject* obj); /* * Clear the expando object for the given DOM proxy and return it. This * function will ensure that the returned object is exposed to active JS if * the given object is exposed. * * GetAndClearExpandoObject does not DROP or clear the preserving wrapper * flag. */ static JSObject* GetAndClearExpandoObject(JSObject* obj); /* * Ensure that the given proxy (obj) has an expando object, and return it. * Returns null on failure. */ static JSObject* EnsureExpandoObject(JSContext* cx, JS::Handle obj); static const char family; }; // Class used by shadowing handlers (the ones that have [OverrideBuiltins]. // This handles tracing the expando in ExpandoAndGeneration. class ShadowingDOMProxyHandler : public DOMProxyHandler { virtual void trace(JSTracer* trc, JSObject* proxy) const override; }; inline bool IsDOMProxy(JSObject *obj) { const js::Class* clasp = js::GetObjectClass(obj); return clasp->isProxy() && js::GetProxyHandler(obj)->family() == &DOMProxyHandler::family; } inline const DOMProxyHandler* GetDOMProxyHandler(JSObject* obj) { MOZ_ASSERT(IsDOMProxy(obj)); return static_cast(js::GetProxyHandler(obj)); } extern jsid s_length_id; // A return value of UINT32_MAX indicates "not an array index". Note, in // particular, that UINT32_MAX itself is not a valid array index in general. inline uint32_t GetArrayIndexFromId(JSContext* cx, JS::Handle id) { // Much like js::IdIsIndex, except with a fast path for "length" and another // fast path for starting with a lowercase ascii char. Is that second one // really needed? I guess it is because StringIsArrayIndex is out of line... if (MOZ_LIKELY(JSID_IS_INT(id))) { return JSID_TO_INT(id); } if (MOZ_LIKELY(id == s_length_id)) { return UINT32_MAX; } if (MOZ_UNLIKELY(!JSID_IS_ATOM(id))) { return UINT32_MAX; } JSLinearString* str = js::AtomToLinearString(JSID_TO_ATOM(id)); char16_t s; { JS::AutoCheckCannotGC nogc; if (js::LinearStringHasLatin1Chars(str)) { s = *js::GetLatin1LinearStringChars(nogc, str); } else { s = *js::GetTwoByteLinearStringChars(nogc, str); } } if (MOZ_LIKELY((unsigned)s >= 'a' && (unsigned)s <= 'z')) return UINT32_MAX; uint32_t i; return js::StringIsArrayIndex(str, &i) ? i : UINT32_MAX; } inline bool IsArrayIndex(uint32_t index) { return index < UINT32_MAX; } inline void FillPropertyDescriptor(JS::MutableHandle desc, JSObject* obj, bool readonly, bool enumerable = true) { desc.object().set(obj); desc.setAttributes((readonly ? JSPROP_READONLY : 0) | (enumerable ? JSPROP_ENUMERATE : 0)); desc.setGetter(nullptr); desc.setSetter(nullptr); } inline void FillPropertyDescriptor(JS::MutableHandle desc, JSObject* obj, const JS::Value& v, bool readonly, bool enumerable = true) { desc.value().set(v); FillPropertyDescriptor(desc, obj, readonly, enumerable); } inline void FillPropertyDescriptor(JS::MutableHandle desc, JSObject* obj, unsigned attributes, const JS::Value& v) { desc.object().set(obj); desc.value().set(v); desc.setAttributes(attributes); desc.setGetter(nullptr); desc.setSetter(nullptr); } } // namespace dom } // namespace mozilla #endif /* mozilla_dom_DOMProxyHandler_h */