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+/* -*- 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"
+
+#define DOM_PROXY_OBJECT_SLOT js::PROXY_PRIVATE_SLOT
+
+namespace mozilla {
+namespace dom {
+
+enum {
+ /**
+ * DOM proxies have an extra slot for the expando object at index
+ * JSPROXYSLOT_EXPANDO.
+ *
+ * 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 JSPROXYSLOT_EXPANDO 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.)
+ */
+ JSPROXYSLOT_EXPANDO = 0
+};
+
+template<typename T> 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<JSObject*> proxy,
+ JS::Handle<jsid> id,
+ JS::MutableHandle<JS::PropertyDescriptor> desc) const override;
+ virtual bool ownPropertyKeys(JSContext* cx, JS::Handle<JSObject*> proxy,
+ JS::AutoIdVector &props) const override;
+
+ virtual bool getPrototypeIfOrdinary(JSContext* cx, JS::Handle<JSObject*> proxy,
+ bool* isOrdinary,
+ JS::MutableHandle<JSObject*> 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<JSObject*> proxy,
+ JS::AutoIdVector &props) const override;
+
+ bool watch(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+ JS::Handle<JSObject*> callable) const override;
+ bool unwatch(JSContext* cx, JS::Handle<JSObject*> proxy,
+ JS::Handle<jsid> 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<JSObject*> 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<JSObject*> proxy,
+ JS::Handle<jsid> id,
+ bool ignoreNamedProps,
+ JS::MutableHandle<JS::PropertyDescriptor> desc) const = 0;
+};
+
+class DOMProxyHandler : public BaseDOMProxyHandler
+{
+public:
+ constexpr DOMProxyHandler()
+ : BaseDOMProxyHandler(&family)
+ {}
+
+ bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+ JS::Handle<JS::PropertyDescriptor> desc,
+ JS::ObjectOpResult &result) const override
+ {
+ bool unused;
+ return defineProperty(cx, proxy, id, desc, result, &unused);
+ }
+ virtual bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+ JS::Handle<JS::PropertyDescriptor> desc,
+ JS::ObjectOpResult &result, bool *defined) const;
+ bool delete_(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+ JS::ObjectOpResult &result) const override;
+ bool preventExtensions(JSContext* cx, JS::Handle<JSObject*> proxy,
+ JS::ObjectOpResult& result) const override;
+ bool isExtensible(JSContext *cx, JS::Handle<JSObject*> proxy, bool *extensible)
+ const override;
+ bool set(JSContext *cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+ JS::Handle<JS::Value> v, JS::Handle<JS::Value> 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<JSObject*> proxy, JS::Handle<jsid> id,
+ JS::Handle<JS::Value> v, bool *done) const;
+
+ /*
+ * Get the expando object for the given DOM proxy.
+ */
+ static JSObject* GetExpandoObject(JSObject* obj);
+
+ /*
+ * Clear the "external references" to this object. If you are not
+ * nsWrapperCAche::ReleaseWrapper, you do NOT want to be calling this method.
+ *
+ * XXXbz if we nixed the DOM expando hash and just had a finalizer that
+ * cleared out the value in the ExpandoAndGeneration in the shadowing case,
+ * could we just get rid of this function altogether?
+ */
+ static void ClearExternalRefsForWrapperRelease(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<JSObject*> 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<const DOMProxyHandler*>(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<jsid> 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<JS::PropertyDescriptor> 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<JS::PropertyDescriptor> 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<JS::PropertyDescriptor> 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 */