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203 lines
7.2 KiB
C++
203 lines
7.2 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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#ifndef js_Realm_h
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#define js_Realm_h
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#include "js/shadow/Realm.h" // JS::shadow::Realm
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#include "js/GCPolicyAPI.h"
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#include "js/TypeDecls.h" // forward-declaration of JS::Realm
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/************************************************************************/
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// [SMDOC] Realms
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//
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// Data associated with a global object. In the browser each frame has its
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// own global/realm.
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namespace js {
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namespace gc {
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JS_PUBLIC_API void TraceRealm(JSTracer* trc, JS::Realm* realm,
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const char* name);
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} // namespace gc
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} // namespace js
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namespace JS {
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class JS_PUBLIC_API AutoRequireNoGC;
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// Each Realm holds a weak reference to its GlobalObject.
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template <>
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struct GCPolicy<Realm*> : public NonGCPointerPolicy<Realm*> {
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static void trace(JSTracer* trc, Realm** vp, const char* name) {
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if (*vp) {
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::js::gc::TraceRealm(trc, *vp, name);
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}
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}
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};
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// Get the current realm, if any. The ECMAScript spec calls this "the current
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// Realm Record".
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extern JS_PUBLIC_API Realm* GetCurrentRealmOrNull(JSContext* cx);
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// Return the compartment that contains a given realm.
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inline JS::Compartment* GetCompartmentForRealm(Realm* realm) {
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return shadow::Realm::get(realm)->compartment();
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}
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// Return an object's realm. All objects except cross-compartment wrappers are
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// created in a particular realm, which never changes. Returns null if obj is
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// a cross-compartment wrapper.
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extern JS_PUBLIC_API Realm* GetObjectRealmOrNull(JSObject* obj);
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// Get the value of the "private data" internal field of the given Realm.
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// This field is initially null and is set using SetRealmPrivate.
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// It's a pointer to embeddding-specific data that SpiderMonkey never uses.
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extern JS_PUBLIC_API void* GetRealmPrivate(Realm* realm);
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// Set the "private data" internal field of the given Realm.
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extern JS_PUBLIC_API void SetRealmPrivate(Realm* realm, void* data);
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typedef void (*DestroyRealmCallback)(JS::GCContext* gcx, Realm* realm);
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// Set the callback SpiderMonkey calls just before garbage-collecting a realm.
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// Embeddings can use this callback to free private data associated with the
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// realm via SetRealmPrivate.
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//
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// By the time this is called, the global object for the realm has already been
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// collected.
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extern JS_PUBLIC_API void SetDestroyRealmCallback(
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JSContext* cx, DestroyRealmCallback callback);
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using RealmNameCallback = void (*)(JSContext* cx, Realm* realm, char* buf,
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size_t bufsize,
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const JS::AutoRequireNoGC& nogc);
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// Set the callback SpiderMonkey calls to get the name of a realm, for
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// diagnostic output.
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extern JS_PUBLIC_API void SetRealmNameCallback(JSContext* cx,
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RealmNameCallback callback);
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// Get the global object for the given realm. This only returns nullptr during
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// GC, between collecting the global object and destroying the Realm.
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extern JS_PUBLIC_API JSObject* GetRealmGlobalOrNull(Realm* realm);
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// Initialize standard JS class constructors, prototypes, and any top-level
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// functions and constants associated with the standard classes (e.g. isNaN
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// for Number).
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extern JS_PUBLIC_API bool InitRealmStandardClasses(JSContext* cx);
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// If the current realm has the non-standard freezeBuiltins option set to true,
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// freeze the constructor object and seal the prototype.
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extern JS_PUBLIC_API bool MaybeFreezeCtorAndPrototype(JSContext* cx,
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HandleObject ctor,
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HandleObject maybeProto);
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/*
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* Ways to get various per-Realm objects. All the getters declared below operate
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* on the JSContext's current Realm.
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*/
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extern JS_PUBLIC_API JSObject* GetRealmObjectPrototype(JSContext* cx);
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extern JS_PUBLIC_API JS::Handle<JSObject*> GetRealmObjectPrototypeHandle(
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JSContext* cx);
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extern JS_PUBLIC_API JSObject* GetRealmFunctionPrototype(JSContext* cx);
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extern JS_PUBLIC_API JSObject* GetRealmArrayPrototype(JSContext* cx);
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extern JS_PUBLIC_API JSObject* GetRealmErrorPrototype(JSContext* cx);
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extern JS_PUBLIC_API JSObject* GetRealmIteratorPrototype(JSContext* cx);
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extern JS_PUBLIC_API JSObject* GetRealmAsyncIteratorPrototype(JSContext* cx);
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// Returns an object that represents the realm, that can be referred from
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// other realm/compartment.
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// See the consumer in `MaybeCrossOriginObjectMixins::EnsureHolder` for details.
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extern JS_PUBLIC_API JSObject* GetRealmKeyObject(JSContext* cx);
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// Implements https://tc39.github.io/ecma262/#sec-getfunctionrealm
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// 7.3.22 GetFunctionRealm ( obj )
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//
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// WARNING: may return a realm in a different compartment!
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//
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// Will throw an exception and return nullptr when a security wrapper or revoked
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// proxy is encountered.
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extern JS_PUBLIC_API Realm* GetFunctionRealm(JSContext* cx,
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HandleObject objArg);
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/** NB: This API is infallible; a nullptr return value does not indicate error.
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*
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* |target| must not be a cross-compartment wrapper because CCWs are not
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* associated with a single realm.
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*
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* Entering a realm roots the realm and its global object until the matching
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* JS::LeaveRealm() call.
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*/
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extern JS_PUBLIC_API JS::Realm* EnterRealm(JSContext* cx, JSObject* target);
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extern JS_PUBLIC_API void LeaveRealm(JSContext* cx, JS::Realm* oldRealm);
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} // namespace JS
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/*
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* At any time, a JSContext has a current (possibly-nullptr) realm. The
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* preferred way to change the current realm is with JSAutoRealm:
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*
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* void foo(JSContext* cx, JSObject* obj) {
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* // in some realm 'r'
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* {
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* JSAutoRealm ar(cx, obj); // constructor enters
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* // in the realm of 'obj'
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* } // destructor leaves
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* // back in realm 'r'
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* }
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*
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* The object passed to JSAutoRealm must *not* be a cross-compartment wrapper,
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* because CCWs are not associated with a single realm.
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*
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* For more complicated uses that don't neatly fit in a C++ stack frame, the
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* realm can be entered and left using separate function calls:
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*
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* void foo(JSContext* cx, JSObject* obj) {
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* // in 'oldRealm'
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* JS::Realm* oldRealm = JS::EnterRealm(cx, obj);
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* // in the realm of 'obj'
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* JS::LeaveRealm(cx, oldRealm);
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* // back in 'oldRealm'
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* }
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*
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* Note: these calls must still execute in a LIFO manner w.r.t all other
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* enter/leave calls on the context. Furthermore, only the return value of a
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* JS::EnterRealm call may be passed as the 'oldRealm' argument of
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* the corresponding JS::LeaveRealm call.
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*
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* Entering a realm roots the realm and its global object for the lifetime of
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* the JSAutoRealm.
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*/
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class MOZ_RAII JS_PUBLIC_API JSAutoRealm {
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JSContext* cx_;
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JS::Realm* oldRealm_;
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public:
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JSAutoRealm(JSContext* cx, JSObject* target);
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JSAutoRealm(JSContext* cx, JSScript* target);
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~JSAutoRealm();
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};
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class MOZ_RAII JS_PUBLIC_API JSAutoNullableRealm {
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JSContext* cx_;
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JS::Realm* oldRealm_;
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public:
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explicit JSAutoNullableRealm(JSContext* cx, JSObject* targetOrNull);
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~JSAutoNullableRealm();
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};
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#endif // js_Realm_h
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