summaryrefslogtreecommitdiffstats
path: root/js/public/Proxy.h
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--js/public/Proxy.h768
1 files changed, 768 insertions, 0 deletions
diff --git a/js/public/Proxy.h b/js/public/Proxy.h
new file mode 100644
index 0000000000..b56bf8140b
--- /dev/null
+++ b/js/public/Proxy.h
@@ -0,0 +1,768 @@
+/* -*- 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 js_Proxy_h
+#define js_Proxy_h
+
+#include "mozilla/Maybe.h"
+
+#include "jstypes.h" // for JS_PUBLIC_API, JS_PUBLIC_DATA
+
+#include "js/Array.h" // JS::IsArrayAnswer
+#include "js/CallNonGenericMethod.h"
+#include "js/Class.h"
+#include "js/HeapAPI.h" // for ObjectIsMarkedBlack
+#include "js/Id.h" // for jsid
+#include "js/Object.h" // JS::GetClass
+#include "js/RootingAPI.h" // for Handle, MutableHandle (ptr only)
+#include "js/shadow/Object.h" // JS::shadow::Object
+#include "js/TypeDecls.h" // for HandleObject, HandleId, HandleValue, MutableHandleIdVector, MutableHandleValue, MutableHand...
+#include "js/Value.h" // for Value, AssertValueIsNotGray, UndefinedValue, ObjectOrNullValue
+
+namespace js {
+
+class RegExpShared;
+
+class JS_PUBLIC_API Wrapper;
+
+/*
+ * [SMDOC] Proxy Objects
+ *
+ * A proxy is a JSObject with highly customizable behavior. ES6 specifies a
+ * single kind of proxy, but the customization mechanisms we use to implement
+ * ES6 Proxy objects are also useful wherever an object with weird behavior is
+ * wanted. Proxies are used to implement:
+ *
+ * - the scope objects used by the Debugger's frame.eval() method
+ * (see js::GetDebugEnvironment)
+ *
+ * - the khuey hack, whereby a whole compartment can be blown away
+ * even if other compartments hold references to objects in it
+ * (see js::NukeCrossCompartmentWrappers)
+ *
+ * - XPConnect security wrappers, which protect chrome from malicious content
+ * (js/xpconnect/wrappers)
+ *
+ * - DOM objects with special property behavior, like named getters
+ * (dom/bindings/Codegen.py generates these proxies from WebIDL)
+ *
+ * ### Proxies and internal methods
+ *
+ * ES2019 specifies 13 internal methods. The runtime semantics of just about
+ * everything a script can do to an object is specified in terms of these
+ * internal methods. For example:
+ *
+ * JS code ES6 internal method that gets called
+ * --------------------------- --------------------------------
+ * obj.prop obj.[[Get]](obj, "prop")
+ * "prop" in obj obj.[[HasProperty]]("prop")
+ * new obj() obj.[[Construct]](<empty argument List>)
+ *
+ * With regard to the implementation of these internal methods, there are three
+ * very different kinds of object in SpiderMonkey.
+ *
+ * 1. Native objects cover most objects and contain both internal slots and
+ * properties. JSClassOps and ObjectOps may be used to override certain
+ * default behaviors.
+ *
+ * 2. Proxy objects are composed of internal slots and a ProxyHandler. The
+ * handler contains C++ methods that can implement these standard (and
+ * non-standard) internal methods. JSClassOps and ObjectOps for the base
+ * ProxyObject invoke the handler methods as appropriate.
+ *
+ * 3. Objects with custom layouts like TypedObjects. These rely on JSClassOps
+ * and ObjectOps to implement internal methods.
+ *
+ * Native objects with custom JSClassOps / ObjectOps are used when the object
+ * behaves very similar to a normal object such as the ArrayObject and it's
+ * length property. Most usages wrapping a C++ or other type should prefer
+ * using a Proxy. Using the proxy approach makes it much easier to create an
+ * ECMAScript and JIT compatible object, particularly if using an appropriate
+ * base class.
+ *
+ * Just about anything you do to a proxy will end up going through a C++
+ * virtual method call. Possibly several. There's no reason the JITs and ICs
+ * can't specialize for particular proxies, based on the handler; but currently
+ * we don't do much of this, so the virtual method overhead typically is
+ * actually incurred.
+ *
+ * ### The proxy handler hierarchy
+ *
+ * A major use case for proxies is to forward each internal method call to
+ * another object, known as its target. The target can be an arbitrary JS
+ * object. Not every proxy has the notion of a target, however.
+ *
+ * To minimize code duplication, a set of abstract proxy handler classes is
+ * provided, from which other handlers may inherit. These abstract classes are
+ * organized in the following hierarchy:
+ *
+ * BaseProxyHandler
+ * |
+ * ForwardingProxyHandler // has a target and forwards internal methods
+ * |
+ * Wrapper // can be unwrapped to reveal target
+ * | // (see js::CheckedUnwrap)
+ * |
+ * CrossCompartmentWrapper // target is in another compartment;
+ * // implements membrane between compartments
+ *
+ * Example: Some DOM objects (including all the arraylike DOM objects) are
+ * implemented as proxies. Since these objects don't need to forward operations
+ * to any underlying JS object, BaseDOMProxyHandler directly subclasses
+ * BaseProxyHandler.
+ *
+ * Gecko's security wrappers are examples of cross-compartment wrappers.
+ *
+ * ### Proxy prototype chains
+ *
+ * While most ECMAScript internal methods are handled by simply calling the
+ * handler method, the [[GetPrototypeOf]] / [[SetPrototypeOf]] behaviors may
+ * follow one of two models:
+ *
+ * 1. A concrete prototype object (or null) is passed to object construction
+ * and ordinary prototype read and write applies. The prototype-related
+ * handler hooks are never called in this case. The [[Prototype]] slot is
+ * used to store the current prototype value.
+ *
+ * 2. TaggedProto::LazyProto is passed to NewProxyObject (or the
+ * ProxyOptions::lazyProto flag is set). Each read or write of the
+ * prototype will invoke the handler. This dynamic prototype behavior may
+ * be useful for wrapper-like objects. If this mode is used the
+ * getPrototype handler at a minimum must be implemented.
+ *
+ * NOTE: In this mode the [[Prototype]] internal slot is unavailable and
+ * must be simulated if needed. This is non-standard, but an
+ * appropriate handler can hide this implementation detail.
+ *
+ * One subtlety here is that ECMAScript has a notion of "ordinary" prototypes.
+ * An object that doesn't override [[GetPrototypeOf]] is considered to have an
+ * ordinary prototype. The getPrototypeIfOrdinary handler must be implemented
+ * by you or your base class. Typically model 1 will be considered "ordinary"
+ * and model 2 will not.
+ */
+
+/*
+ * BaseProxyHandler is the most generic kind of proxy handler. It does not make
+ * any assumptions about the target. Consequently, it does not provide any
+ * default implementation for most methods. As a convenience, a few high-level
+ * methods, like get() and set(), are given default implementations that work by
+ * calling the low-level methods, like getOwnPropertyDescriptor().
+ *
+ * Important: If you add a method here, you should probably also add a
+ * Proxy::foo entry point with an AutoEnterPolicy. If you don't, you need an
+ * explicit override for the method in SecurityWrapper. See bug 945826 comment
+ * 0.
+ */
+class JS_PUBLIC_API BaseProxyHandler {
+ /*
+ * Sometimes it's desirable to designate groups of proxy handlers as
+ * "similar". For this, we use the notion of a "family": A consumer-provided
+ * opaque pointer that designates the larger group to which this proxy
+ * belongs.
+ *
+ * If it will never be important to differentiate this proxy from others as
+ * part of a distinct group, nullptr may be used instead.
+ */
+ const void* mFamily;
+
+ /*
+ * Proxy handlers can use mHasPrototype to request the following special
+ * treatment from the JS engine:
+ *
+ * - When mHasPrototype is true, the engine never calls these methods:
+ * has, set, enumerate, iterate. Instead, for these operations,
+ * it calls the "own" methods like getOwnPropertyDescriptor, hasOwn,
+ * defineProperty, getOwnEnumerablePropertyKeys, etc.,
+ * and consults the prototype chain if needed.
+ *
+ * - When mHasPrototype is true, the engine calls handler->get() only if
+ * handler->hasOwn() says an own property exists on the proxy. If not,
+ * it consults the prototype chain.
+ *
+ * This is useful because it frees the ProxyHandler from having to implement
+ * any behavior having to do with the prototype chain.
+ */
+ bool mHasPrototype;
+
+ /*
+ * All proxies indicate whether they have any sort of interesting security
+ * policy that might prevent the caller from doing something it wants to
+ * the object. In the case of wrappers, this distinction is used to
+ * determine whether the caller may strip off the wrapper if it so desires.
+ */
+ bool mHasSecurityPolicy;
+
+ public:
+ explicit constexpr BaseProxyHandler(const void* aFamily,
+ bool aHasPrototype = false,
+ bool aHasSecurityPolicy = false)
+ : mFamily(aFamily),
+ mHasPrototype(aHasPrototype),
+ mHasSecurityPolicy(aHasSecurityPolicy) {}
+
+ bool hasPrototype() const { return mHasPrototype; }
+
+ bool hasSecurityPolicy() const { return mHasSecurityPolicy; }
+
+ inline const void* family() const { return mFamily; }
+ static size_t offsetOfFamily() { return offsetof(BaseProxyHandler, mFamily); }
+
+ virtual bool finalizeInBackground(const JS::Value& priv) const {
+ /*
+ * Called on creation of a proxy to determine whether its finalize
+ * method can be finalized on the background thread.
+ */
+ return true;
+ }
+
+ virtual bool canNurseryAllocate() const {
+ /*
+ * Nursery allocation is allowed if and only if it is safe to not
+ * run |finalize| when the ProxyObject dies.
+ */
+ return false;
+ }
+
+ /* Policy enforcement methods.
+ *
+ * enter() allows the policy to specify whether the caller may perform |act|
+ * on the proxy's |id| property. In the case when |act| is CALL, |id| is
+ * generally JSID_VOID. The |mayThrow| parameter indicates whether a
+ * handler that wants to throw custom exceptions when denying should do so
+ * or not.
+ *
+ * The |act| parameter to enter() specifies the action being performed.
+ * If |bp| is false, the method suggests that the caller throw (though it
+ * may still decide to squelch the error).
+ *
+ * We make these OR-able so that assertEnteredPolicy can pass a union of them.
+ * For example, get{,Own}PropertyDescriptor is invoked by calls to ::get()
+ * ::set(), in addition to being invoked on its own, so there are several
+ * valid Actions that could have been entered.
+ */
+ typedef uint32_t Action;
+ enum {
+ NONE = 0x00,
+ GET = 0x01,
+ SET = 0x02,
+ CALL = 0x04,
+ ENUMERATE = 0x08,
+ GET_PROPERTY_DESCRIPTOR = 0x10
+ };
+
+ virtual bool enter(JSContext* cx, JS::HandleObject wrapper, JS::HandleId id,
+ Action act, bool mayThrow, bool* bp) const;
+
+ /* Standard internal methods. */
+ virtual bool getOwnPropertyDescriptor(
+ JSContext* cx, JS::HandleObject proxy, JS::HandleId id,
+ JS::MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> desc) const = 0;
+ virtual bool defineProperty(JSContext* cx, JS::HandleObject proxy,
+ JS::HandleId id,
+ JS::Handle<JS::PropertyDescriptor> desc,
+ JS::ObjectOpResult& result) const = 0;
+ virtual bool ownPropertyKeys(JSContext* cx, JS::HandleObject proxy,
+ JS::MutableHandleIdVector props) const = 0;
+ virtual bool delete_(JSContext* cx, JS::HandleObject proxy, JS::HandleId id,
+ JS::ObjectOpResult& result) const = 0;
+
+ /*
+ * These methods are standard, but the engine does not normally call them.
+ * They're opt-in. See "Proxy prototype chains" above.
+ *
+ * getPrototype() crashes if called. setPrototype() throws a TypeError.
+ */
+ virtual bool getPrototype(JSContext* cx, JS::HandleObject proxy,
+ JS::MutableHandleObject protop) const;
+ virtual bool setPrototype(JSContext* cx, JS::HandleObject proxy,
+ JS::HandleObject proto,
+ JS::ObjectOpResult& result) const;
+
+ /* Non-standard but conceptual kin to {g,s}etPrototype, so these live here. */
+ virtual bool getPrototypeIfOrdinary(JSContext* cx, JS::HandleObject proxy,
+ bool* isOrdinary,
+ JS::MutableHandleObject protop) const = 0;
+ virtual bool setImmutablePrototype(JSContext* cx, JS::HandleObject proxy,
+ bool* succeeded) const;
+
+ virtual bool preventExtensions(JSContext* cx, JS::HandleObject proxy,
+ JS::ObjectOpResult& result) const = 0;
+ virtual bool isExtensible(JSContext* cx, JS::HandleObject proxy,
+ bool* extensible) const = 0;
+
+ /*
+ * These standard internal methods are implemented, as a convenience, so
+ * that ProxyHandler subclasses don't have to provide every single method.
+ *
+ * The base-class implementations work by calling getOwnPropertyDescriptor()
+ * and going up the [[Prototype]] chain if necessary. The algorithm for this
+ * follows what is defined for Ordinary Objects in the ES spec.
+ * They do not follow any standard. When in doubt, override them.
+ */
+ virtual bool has(JSContext* cx, JS::HandleObject proxy, JS::HandleId id,
+ bool* bp) const;
+ virtual bool get(JSContext* cx, JS::HandleObject proxy,
+ JS::HandleValue receiver, JS::HandleId id,
+ JS::MutableHandleValue vp) const;
+ virtual bool set(JSContext* cx, JS::HandleObject proxy, JS::HandleId id,
+ JS::HandleValue v, JS::HandleValue receiver,
+ JS::ObjectOpResult& result) const;
+
+ // Use the ProxyExpando object for private fields, rather than taking the
+ // normal get/set/defineField paths.
+ virtual bool useProxyExpandoObjectForPrivateFields() const { return true; }
+
+ // For some exotic objects (WindowProxy, Location), we want to be able to
+ // throw rather than allow private fields on these objects.
+ //
+ // As a simplfying assumption, if throwOnPrivateFields returns true,
+ // we should also return true to useProxyExpandoObjectForPrivateFields.
+ virtual bool throwOnPrivateField() const { return false; }
+
+ /*
+ * [[Call]] and [[Construct]] are standard internal methods but according
+ * to the spec, they are not present on every object.
+ *
+ * SpiderMonkey never calls a proxy's call()/construct() internal method
+ * unless isCallable()/isConstructor() returns true for that proxy.
+ *
+ * BaseProxyHandler::isCallable()/isConstructor() always return false, and
+ * BaseProxyHandler::call()/construct() crash if called. So if you're
+ * creating a kind of that is never callable, you don't have to override
+ * anything, but otherwise you probably want to override all four.
+ */
+ virtual bool call(JSContext* cx, JS::HandleObject proxy,
+ const JS::CallArgs& args) const;
+ virtual bool construct(JSContext* cx, JS::HandleObject proxy,
+ const JS::CallArgs& args) const;
+
+ /* SpiderMonkey extensions. */
+ virtual bool enumerate(JSContext* cx, JS::HandleObject proxy,
+ JS::MutableHandleIdVector props) const;
+ virtual bool hasOwn(JSContext* cx, JS::HandleObject proxy, JS::HandleId id,
+ bool* bp) const;
+ virtual bool getOwnEnumerablePropertyKeys(
+ JSContext* cx, JS::HandleObject proxy,
+ JS::MutableHandleIdVector props) const;
+ virtual bool nativeCall(JSContext* cx, JS::IsAcceptableThis test,
+ JS::NativeImpl impl, const JS::CallArgs& args) const;
+ virtual bool getBuiltinClass(JSContext* cx, JS::HandleObject proxy,
+ ESClass* cls) const;
+ virtual bool isArray(JSContext* cx, JS::HandleObject proxy,
+ JS::IsArrayAnswer* answer) const;
+ virtual const char* className(JSContext* cx, JS::HandleObject proxy) const;
+ virtual JSString* fun_toString(JSContext* cx, JS::HandleObject proxy,
+ bool isToSource) const;
+ virtual RegExpShared* regexp_toShared(JSContext* cx,
+ JS::HandleObject proxy) const;
+ virtual bool boxedValue_unbox(JSContext* cx, JS::HandleObject proxy,
+ JS::MutableHandleValue vp) const;
+ virtual void trace(JSTracer* trc, JSObject* proxy) const;
+ virtual void finalize(JS::GCContext* gcx, JSObject* proxy) const;
+ virtual size_t objectMoved(JSObject* proxy, JSObject* old) const;
+
+ // Allow proxies, wrappers in particular, to specify callability at runtime.
+ // Note: These do not take const JSObject*, but they do in spirit.
+ // We are not prepared to do this, as there's little const correctness
+ // in the external APIs that handle proxies.
+ virtual bool isCallable(JSObject* obj) const;
+ virtual bool isConstructor(JSObject* obj) const;
+
+ virtual bool getElements(JSContext* cx, JS::HandleObject proxy,
+ uint32_t begin, uint32_t end,
+ ElementAdder* adder) const;
+
+ virtual bool isScripted() const { return false; }
+};
+
+extern JS_PUBLIC_DATA const JSClass ProxyClass;
+
+inline bool IsProxy(const JSObject* obj) {
+ return reinterpret_cast<const JS::shadow::Object*>(obj)->shape->isProxy();
+}
+
+namespace detail {
+
+// Proxy slot layout
+// -----------------
+//
+// Every proxy has a ProxyValueArray that contains the following Values:
+//
+// - The expando slot. This is used to hold private fields should they be
+// stamped into a non-forwarding proxy type.
+// - The private slot.
+// - The reserved slots. The number of slots is determined by the proxy's Class.
+//
+// Proxy objects store a pointer to the reserved slots (ProxyReservedSlots*).
+// The ProxyValueArray and the private slot can be accessed using
+// ProxyValueArray::fromReservedSlots or ProxyDataLayout::values.
+//
+// Storing a pointer to ProxyReservedSlots instead of ProxyValueArray has a
+// number of advantages. In particular, it means JS::GetReservedSlot and
+// JS::SetReservedSlot can be used with both proxies and native objects. This
+// works because the ProxyReservedSlots* pointer is stored where native objects
+// store their dynamic slots pointer.
+
+struct ProxyReservedSlots {
+ JS::Value slots[1];
+
+ static constexpr ptrdiff_t offsetOfPrivateSlot();
+
+ static inline int offsetOfSlot(size_t slot) {
+ return offsetof(ProxyReservedSlots, slots[0]) + slot * sizeof(JS::Value);
+ }
+
+ void init(size_t nreserved) {
+ for (size_t i = 0; i < nreserved; i++) {
+ slots[i] = JS::UndefinedValue();
+ }
+ }
+
+ ProxyReservedSlots(const ProxyReservedSlots&) = delete;
+ void operator=(const ProxyReservedSlots&) = delete;
+};
+
+struct ProxyValueArray {
+ JS::Value expandoSlot;
+ JS::Value privateSlot;
+ ProxyReservedSlots reservedSlots;
+
+ void init(size_t nreserved) {
+ expandoSlot = JS::ObjectOrNullValue(nullptr);
+ privateSlot = JS::UndefinedValue();
+ reservedSlots.init(nreserved);
+ }
+
+ static MOZ_ALWAYS_INLINE ProxyValueArray* fromReservedSlots(
+ ProxyReservedSlots* slots) {
+ uintptr_t p = reinterpret_cast<uintptr_t>(slots);
+ return reinterpret_cast<ProxyValueArray*>(p - offsetOfReservedSlots());
+ }
+ static constexpr size_t offsetOfReservedSlots() {
+ return offsetof(ProxyValueArray, reservedSlots);
+ }
+
+ static size_t allocCount(size_t nreserved) {
+ static_assert(offsetOfReservedSlots() % sizeof(JS::Value) == 0);
+ return offsetOfReservedSlots() / sizeof(JS::Value) + nreserved;
+ }
+ static size_t sizeOf(size_t nreserved) {
+ return allocCount(nreserved) * sizeof(JS::Value);
+ }
+
+ ProxyValueArray(const ProxyValueArray&) = delete;
+ void operator=(const ProxyValueArray&) = delete;
+};
+
+/* static */
+constexpr ptrdiff_t ProxyReservedSlots::offsetOfPrivateSlot() {
+ return -ptrdiff_t(ProxyValueArray::offsetOfReservedSlots()) +
+ offsetof(ProxyValueArray, privateSlot);
+}
+
+// All proxies share the same data layout. Following the object's shape and
+// type, the proxy has a ProxyDataLayout structure with a pointer to an array
+// of values and the proxy's handler. This is designed both so that proxies can
+// be easily swapped with other objects (via RemapWrapper) and to mimic the
+// layout of other objects (proxies and other objects have the same size) so
+// that common code can access either type of object.
+//
+// See GetReservedOrProxyPrivateSlot below.
+struct ProxyDataLayout {
+ ProxyReservedSlots* reservedSlots;
+ const BaseProxyHandler* handler;
+
+ MOZ_ALWAYS_INLINE ProxyValueArray* values() const {
+ return ProxyValueArray::fromReservedSlots(reservedSlots);
+ }
+};
+
+#ifdef JS_64BIT
+constexpr uint32_t ProxyDataOffset = 1 * sizeof(void*);
+#else
+constexpr uint32_t ProxyDataOffset = 2 * sizeof(void*);
+#endif
+
+inline ProxyDataLayout* GetProxyDataLayout(JSObject* obj) {
+ MOZ_ASSERT(IsProxy(obj));
+ return reinterpret_cast<ProxyDataLayout*>(reinterpret_cast<uint8_t*>(obj) +
+ ProxyDataOffset);
+}
+
+inline const ProxyDataLayout* GetProxyDataLayout(const JSObject* obj) {
+ MOZ_ASSERT(IsProxy(obj));
+ return reinterpret_cast<const ProxyDataLayout*>(
+ reinterpret_cast<const uint8_t*>(obj) + ProxyDataOffset);
+}
+
+JS_PUBLIC_API void SetValueInProxy(JS::Value* slot, const JS::Value& value);
+
+inline void SetProxyReservedSlotUnchecked(JSObject* obj, size_t n,
+ const JS::Value& extra) {
+ MOZ_ASSERT(n < JSCLASS_RESERVED_SLOTS(JS::GetClass(obj)));
+
+ JS::Value* vp = &GetProxyDataLayout(obj)->reservedSlots->slots[n];
+
+ // Trigger a barrier before writing the slot.
+ if (vp->isGCThing() || extra.isGCThing()) {
+ SetValueInProxy(vp, extra);
+ } else {
+ *vp = extra;
+ }
+}
+
+} // namespace detail
+
+inline const BaseProxyHandler* GetProxyHandler(const JSObject* obj) {
+ return detail::GetProxyDataLayout(obj)->handler;
+}
+
+inline const JS::Value& GetProxyPrivate(const JSObject* obj) {
+ return detail::GetProxyDataLayout(obj)->values()->privateSlot;
+}
+
+inline const JS::Value& GetProxyExpando(const JSObject* obj) {
+ return detail::GetProxyDataLayout(obj)->values()->expandoSlot;
+}
+
+inline JSObject* GetProxyTargetObject(const JSObject* obj) {
+ return GetProxyPrivate(obj).toObjectOrNull();
+}
+
+inline const JS::Value& GetProxyReservedSlot(const JSObject* obj, size_t n) {
+ MOZ_ASSERT(n < JSCLASS_RESERVED_SLOTS(JS::GetClass(obj)));
+ return detail::GetProxyDataLayout(obj)->reservedSlots->slots[n];
+}
+
+inline void SetProxyHandler(JSObject* obj, const BaseProxyHandler* handler) {
+ detail::GetProxyDataLayout(obj)->handler = handler;
+}
+
+inline void SetProxyReservedSlot(JSObject* obj, size_t n,
+ const JS::Value& extra) {
+#ifdef DEBUG
+ if (gc::detail::ObjectIsMarkedBlack(obj)) {
+ JS::AssertValueIsNotGray(extra);
+ }
+#endif
+
+ detail::SetProxyReservedSlotUnchecked(obj, n, extra);
+}
+
+inline void SetProxyPrivate(JSObject* obj, const JS::Value& value) {
+#ifdef DEBUG
+ if (gc::detail::ObjectIsMarkedBlack(obj)) {
+ JS::AssertValueIsNotGray(value);
+ }
+#endif
+
+ JS::Value* vp = &detail::GetProxyDataLayout(obj)->values()->privateSlot;
+
+ // Trigger a barrier before writing the slot.
+ if (vp->isGCThing() || value.isGCThing()) {
+ detail::SetValueInProxy(vp, value);
+ } else {
+ *vp = value;
+ }
+}
+
+inline bool IsScriptedProxy(const JSObject* obj) {
+ return IsProxy(obj) && GetProxyHandler(obj)->isScripted();
+}
+
+class MOZ_STACK_CLASS ProxyOptions {
+ protected:
+ /* protected constructor for subclass */
+ explicit ProxyOptions(bool lazyProtoArg)
+ : lazyProto_(lazyProtoArg), clasp_(&ProxyClass) {}
+
+ public:
+ ProxyOptions() : ProxyOptions(false) {}
+
+ bool lazyProto() const { return lazyProto_; }
+ ProxyOptions& setLazyProto(bool flag) {
+ lazyProto_ = flag;
+ return *this;
+ }
+
+ const JSClass* clasp() const { return clasp_; }
+ ProxyOptions& setClass(const JSClass* claspArg) {
+ clasp_ = claspArg;
+ return *this;
+ }
+
+ private:
+ bool lazyProto_;
+ const JSClass* clasp_;
+};
+
+JS_PUBLIC_API JSObject* NewProxyObject(
+ JSContext* cx, const BaseProxyHandler* handler, JS::HandleValue priv,
+ JSObject* proto, const ProxyOptions& options = ProxyOptions());
+
+JSObject* RenewProxyObject(JSContext* cx, JSObject* obj,
+ BaseProxyHandler* handler, const JS::Value& priv);
+
+class JS_PUBLIC_API AutoEnterPolicy {
+ public:
+ typedef BaseProxyHandler::Action Action;
+ AutoEnterPolicy(JSContext* cx, const BaseProxyHandler* handler,
+ JS::HandleObject wrapper, JS::HandleId id, Action act,
+ bool mayThrow)
+#ifdef JS_DEBUG
+ : context(nullptr)
+#endif
+ {
+ allow = handler->hasSecurityPolicy()
+ ? handler->enter(cx, wrapper, id, act, mayThrow, &rv)
+ : true;
+ recordEnter(cx, wrapper, id, act);
+ // We want to throw an exception if all of the following are true:
+ // * The policy disallowed access.
+ // * The policy set rv to false, indicating that we should throw.
+ // * The caller did not instruct us to ignore exceptions.
+ // * The policy did not throw itself.
+ if (!allow && !rv && mayThrow) {
+ reportErrorIfExceptionIsNotPending(cx, id);
+ }
+ }
+
+ virtual ~AutoEnterPolicy() { recordLeave(); }
+ inline bool allowed() { return allow; }
+ inline bool returnValue() {
+ MOZ_ASSERT(!allowed());
+ return rv;
+ }
+
+ protected:
+ // no-op constructor for subclass
+ AutoEnterPolicy()
+#ifdef JS_DEBUG
+ : context(nullptr),
+ enteredAction(BaseProxyHandler::NONE)
+#endif
+ {
+ }
+ void reportErrorIfExceptionIsNotPending(JSContext* cx, JS::HandleId id);
+ bool allow;
+ bool rv;
+
+#ifdef JS_DEBUG
+ JSContext* context;
+ mozilla::Maybe<JS::HandleObject> enteredProxy;
+ mozilla::Maybe<JS::HandleId> enteredId;
+ Action enteredAction;
+
+ // NB: We explicitly don't track the entered action here, because sometimes
+ // set() methods do an implicit get() during their implementation, leading
+ // to spurious assertions.
+ AutoEnterPolicy* prev;
+ void recordEnter(JSContext* cx, JS::HandleObject proxy, JS::HandleId id,
+ Action act);
+ void recordLeave();
+
+ friend JS_PUBLIC_API void assertEnteredPolicy(JSContext* cx, JSObject* proxy,
+ jsid id, Action act);
+#else
+ inline void recordEnter(JSContext* cx, JSObject* proxy, jsid id, Action act) {
+ }
+ inline void recordLeave() {}
+#endif
+
+ private:
+ // This operator needs to be deleted explicitly, otherwise Visual C++ will
+ // create it automatically when it is part of the export JS API. In that
+ // case, compile would fail because HandleId is not allowed to be assigned
+ // and consequently instantiation of assign operator of mozilla::Maybe
+ // would fail. See bug 1325351 comment 16. Copy constructor is removed at
+ // the same time for consistency.
+ AutoEnterPolicy(const AutoEnterPolicy&) = delete;
+ AutoEnterPolicy& operator=(const AutoEnterPolicy&) = delete;
+};
+
+#ifdef JS_DEBUG
+class JS_PUBLIC_API AutoWaivePolicy : public AutoEnterPolicy {
+ public:
+ AutoWaivePolicy(JSContext* cx, JS::HandleObject proxy, JS::HandleId id,
+ BaseProxyHandler::Action act) {
+ allow = true;
+ recordEnter(cx, proxy, id, act);
+ }
+};
+#else
+class JS_PUBLIC_API AutoWaivePolicy {
+ public:
+ AutoWaivePolicy(JSContext* cx, JS::HandleObject proxy, JS::HandleId id,
+ BaseProxyHandler::Action act) {}
+};
+#endif
+
+#ifdef JS_DEBUG
+extern JS_PUBLIC_API void assertEnteredPolicy(JSContext* cx, JSObject* obj,
+ jsid id,
+ BaseProxyHandler::Action act);
+#else
+inline void assertEnteredPolicy(JSContext* cx, JSObject* obj, jsid id,
+ BaseProxyHandler::Action act) {}
+#endif
+
+extern JS_PUBLIC_DATA const JSClassOps ProxyClassOps;
+extern JS_PUBLIC_DATA const js::ClassExtension ProxyClassExtension;
+extern JS_PUBLIC_DATA const js::ObjectOps ProxyObjectOps;
+
+template <unsigned Flags>
+constexpr unsigned CheckProxyFlags() {
+ constexpr size_t reservedSlots =
+ (Flags >> JSCLASS_RESERVED_SLOTS_SHIFT) & JSCLASS_RESERVED_SLOTS_MASK;
+
+ // For now assert each Proxy Class has at least 1 reserved slot. This is
+ // not a hard requirement, but helps catch Classes that need an explicit
+ // JSCLASS_HAS_RESERVED_SLOTS since bug 1360523.
+ static_assert(reservedSlots > 0,
+ "Proxy Classes must have at least 1 reserved slot");
+
+ constexpr size_t numSlots =
+ offsetof(js::detail::ProxyValueArray, reservedSlots) / sizeof(JS::Value);
+
+ // ProxyValueArray must fit inline in the object, so assert the number of
+ // slots does not exceed MAX_FIXED_SLOTS.
+ static_assert(numSlots + reservedSlots <= JS::shadow::Object::MAX_FIXED_SLOTS,
+ "ProxyValueArray size must not exceed max JSObject size");
+
+ // Proxies must not have the JSCLASS_SKIP_NURSERY_FINALIZE flag set: they
+ // always have finalizers, and whether they can be nursery allocated is
+ // controlled by the canNurseryAllocate() method on the proxy handler.
+ static_assert(!(Flags & JSCLASS_SKIP_NURSERY_FINALIZE),
+ "Proxies must not use JSCLASS_SKIP_NURSERY_FINALIZE; use "
+ "the canNurseryAllocate() proxy handler method instead.");
+ return Flags;
+}
+
+#define PROXY_CLASS_DEF_WITH_CLASS_SPEC(name, flags, classSpec) \
+ { \
+ name, \
+ JSClass::NON_NATIVE | JSCLASS_IS_PROXY | \
+ JSCLASS_DELAY_METADATA_BUILDER | js::CheckProxyFlags<flags>(), \
+ &js::ProxyClassOps, classSpec, &js::ProxyClassExtension, \
+ &js::ProxyObjectOps \
+ }
+
+#define PROXY_CLASS_DEF(name, flags) \
+ PROXY_CLASS_DEF_WITH_CLASS_SPEC(name, flags, JS_NULL_CLASS_SPEC)
+
+// Converts a proxy into a DeadObjectProxy that will throw exceptions on all
+// access. This will run the proxy's finalizer to perform clean-up before the
+// conversion happens.
+JS_PUBLIC_API void NukeNonCCWProxy(JSContext* cx, JS::HandleObject proxy);
+
+// This is a variant of js::NukeNonCCWProxy() for CCWs. It should only be called
+// on CCWs that have been removed from CCW tables.
+JS_PUBLIC_API void NukeRemovedCrossCompartmentWrapper(JSContext* cx,
+ JSObject* wrapper);
+
+} /* namespace js */
+
+#endif /* js_Proxy_h */