tor-browser

The Tor Browser
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DOMProxy.h (3211B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
      2 * vim: set ts=8 sts=2 et sw=2 tw=80:
      3 * This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 /*
      8 * Specify information about DOMProxy proxies in the DOM, for use by ICs.
      9 *
     10 * Embedders who don't need to define particularly high-performance proxies that
     11 * can have random properties added to them can ignore this header.
     12 */
     13 
     14 #ifndef js_friend_DOMProxy_h
     15 #define js_friend_DOMProxy_h
     16 
     17 #include <stddef.h>  // size_t
     18 #include <stdint.h>  // uint64_t
     19 
     20 #include "jstypes.h"  // JS_PUBLIC_API
     21 
     22 #include "js/Id.h"          // JS::PropertyKey
     23 #include "js/RootingAPI.h"  // JS::Handle, JS::Heap
     24 #include "js/Value.h"       // JS::UndefinedValue, JS::Value
     25 
     26 struct JS_PUBLIC_API JSContext;
     27 class JS_PUBLIC_API JSObject;
     28 
     29 namespace JS {
     30 
     31 /*
     32 * The DOMProxyShadowsCheck function will be called to check if the property for
     33 * id should be gotten from the prototype, or if there is an own property that
     34 * shadows it.
     35 * * If ShadowsViaDirectExpando is returned, then the slot at
     36 *   listBaseExpandoSlot contains an expando object which has the property in
     37 *   question.
     38 * * If ShadowsViaIndirectExpando is returned, then the slot at
     39 *   listBaseExpandoSlot contains a private pointer to an ExpandoAndGeneration
     40 *   and the expando object in the ExpandoAndGeneration has the property in
     41 *   question.
     42 * * If DoesntShadow is returned then the slot at listBaseExpandoSlot should
     43 *   either be undefined or point to an expando object that would contain the
     44 *   own property.
     45 * * If DoesntShadowUnique is returned then the slot at listBaseExpandoSlot
     46 *   should contain a private pointer to a ExpandoAndGeneration, which contains
     47 *   a JS::Value that should either be undefined or point to an expando object,
     48 *   and a uint64 value. If that value changes then the IC for getting a
     49 *   property will be invalidated.
     50 * * If Shadows is returned, that means the property is an own property of the
     51 *   proxy but doesn't live on the expando object.
     52 */
     53 
     54 struct ExpandoAndGeneration {
     55  ExpandoAndGeneration() : expando(JS::UndefinedValue()), generation(0) {}
     56 
     57  void OwnerUnlinked() { ++generation; }
     58 
     59  static constexpr size_t offsetOfExpando() {
     60    return offsetof(ExpandoAndGeneration, expando);
     61  }
     62 
     63  static constexpr size_t offsetOfGeneration() {
     64    return offsetof(ExpandoAndGeneration, generation);
     65  }
     66 
     67  Heap<Value> expando;
     68  uint64_t generation;
     69 };
     70 
     71 enum class DOMProxyShadowsResult {
     72  ShadowCheckFailed,
     73  Shadows,
     74  DoesntShadow,
     75  DoesntShadowUnique,
     76  ShadowsViaDirectExpando,
     77  ShadowsViaIndirectExpando
     78 };
     79 
     80 using DOMProxyShadowsCheck = DOMProxyShadowsResult (*)(JSContext*,
     81                                                       Handle<JSObject*>,
     82                                                       Handle<JS::PropertyKey>);
     83 
     84 extern JS_PUBLIC_API void SetDOMProxyInformation(
     85    const void* domProxyHandlerFamily,
     86    DOMProxyShadowsCheck domProxyShadowsCheck,
     87    const void* domRemoteProxyHandlerFamily);
     88 
     89 }  // namespace JS
     90 
     91 #endif  // js_friend_DOMProxy_h