Source code
Revision control
Copy as Markdown
Other Tools
/* -*- 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
#ifndef XrayWrapper_h
#define XrayWrapper_h
#include "mozilla/Maybe.h"
#include "WrapperFactory.h"
#include "jsapi.h"
#include "jsfriendapi.h"
#include "js/friend/XrayJitInfo.h" // JS::XrayJitInfo
#include "js/Object.h" // JS::GetReservedSlot
#include "js/Proxy.h"
#include "js/Wrapper.h"
// Slot where Xray functions for Web IDL methods store a pointer to
// the Xray wrapper they're associated with.
#define XRAY_DOM_FUNCTION_PARENT_WRAPPER_SLOT 0
// Slot where in debug builds Xray functions for Web IDL methods store
// a pointer to their themselves, just so we can assert that they're the
// sort of functions we expect.
#define XRAY_DOM_FUNCTION_NATIVE_SLOT_FOR_SELF 1
// Xray wrappers re-resolve the original native properties on the native
// object and always directly access to those properties.
// Because they work so differently from the rest of the wrapper hierarchy,
// we pull them out of the Wrapper inheritance hierarchy and create a
// little world around them.
class nsIPrincipal;
namespace xpc {
enum XrayType {
XrayForDOMObject,
XrayForJSObject,
XrayForOpaqueObject,
NotXray
};
class XrayTraits {
public:
constexpr XrayTraits() = default;
static JSObject* getTargetObject(JSObject* wrapper) {
JSObject* target =
js::UncheckedUnwrap(wrapper, /* stopAtWindowProxy = */ false);
if (target) {
JS::ExposeObjectToActiveJS(target);
}
return target;
}
// NB: resolveOwnProperty may decide whether or not to cache what it finds
// on the holder. If the result is not cached, the lookup will happen afresh
// for each access, which is the right thing for things like dynamic NodeList
// properties.
virtual bool resolveOwnProperty(
JSContext* cx, JS::HandleObject wrapper, JS::HandleObject target,
JS::HandleObject holder, JS::HandleId id,
JS::MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> desc);
bool delete_(JSContext* cx, JS::HandleObject wrapper, JS::HandleId id,
JS::ObjectOpResult& result) {
return result.succeed();
}
static bool getBuiltinClass(JSContext* cx, JS::HandleObject wrapper,
const js::Wrapper& baseInstance,
js::ESClass* cls) {
return baseInstance.getBuiltinClass(cx, wrapper, cls);
}
static const char* className(JSContext* cx, JS::HandleObject wrapper,
const js::Wrapper& baseInstance) {
return baseInstance.className(cx, wrapper);
}
virtual void preserveWrapper(JSObject* target) = 0;
bool getExpandoObject(JSContext* cx, JS::HandleObject target,
JS::HandleObject consumer,
JS::MutableHandleObject expandObject);
JSObject* ensureExpandoObject(JSContext* cx, JS::HandleObject wrapper,
JS::HandleObject target);
// Slots for holder objects.
enum {
HOLDER_SLOT_CACHED_PROTO = 0,
HOLDER_SLOT_EXPANDO = 1,
HOLDER_SHARED_SLOT_COUNT
};
static JSObject* getHolder(JSObject* wrapper);
JSObject* ensureHolder(JSContext* cx, JS::HandleObject wrapper);
virtual JSObject* createHolder(JSContext* cx, JSObject* wrapper) = 0;
JSObject* getExpandoChain(JS::HandleObject obj);
JSObject* detachExpandoChain(JS::HandleObject obj);
bool setExpandoChain(JSContext* cx, JS::HandleObject obj,
JS::HandleObject chain);
bool cloneExpandoChain(JSContext* cx, JS::HandleObject dst,
JS::HandleObject srcChain);
protected:
static const JSClass HolderClass;
// Get the JSClass we should use for our expando object.
virtual const JSClass* getExpandoClass(JSContext* cx,
JS::HandleObject target) const;
private:
bool expandoObjectMatchesConsumer(JSContext* cx,
JS::HandleObject expandoObject,
nsIPrincipal* consumerOrigin);
// |expandoChain| is the expando chain in the wrapped object's compartment.
// |exclusiveWrapper| is any xray that has exclusive use of the expando.
// |cx| may be in any compartment.
bool getExpandoObjectInternal(JSContext* cx, JSObject* expandoChain,
JS::HandleObject exclusiveWrapper,
nsIPrincipal* origin,
JS::MutableHandleObject expandoObject);
// |cx| is in the target's compartment, and |exclusiveWrapper| is any xray
// that has exclusive use of the expando. |exclusiveWrapperGlobal| is the
// caller's global and must be same-compartment with |exclusiveWrapper|.
JSObject* attachExpandoObject(JSContext* cx, JS::HandleObject target,
JS::HandleObject exclusiveWrapper,
JS::HandleObject exclusiveWrapperGlobal,
nsIPrincipal* origin);
XrayTraits(XrayTraits&) = delete;
const XrayTraits& operator=(XrayTraits&) = delete;
};
class DOMXrayTraits : public XrayTraits {
public:
constexpr DOMXrayTraits() = default;
static const XrayType Type = XrayForDOMObject;
virtual bool resolveOwnProperty(
JSContext* cx, JS::HandleObject wrapper, JS::HandleObject target,
JS::HandleObject holder, JS::HandleId id,
JS::MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> desc) override;
bool delete_(JSContext* cx, JS::HandleObject wrapper, JS::HandleId id,
JS::ObjectOpResult& result);
bool defineProperty(
JSContext* cx, JS::HandleObject wrapper, JS::HandleId id,
JS::Handle<JS::PropertyDescriptor> desc,
JS::Handle<mozilla::Maybe<JS::PropertyDescriptor>> existingDesc,
JS::Handle<JSObject*> existingHolder, JS::ObjectOpResult& result,
bool* done);
virtual bool enumerateNames(JSContext* cx, JS::HandleObject wrapper,
unsigned flags, JS::MutableHandleIdVector props);
static bool call(JSContext* cx, JS::HandleObject wrapper,
const JS::CallArgs& args, const js::Wrapper& baseInstance);
static bool construct(JSContext* cx, JS::HandleObject wrapper,
const JS::CallArgs& args,
const js::Wrapper& baseInstance);
static bool getPrototype(JSContext* cx, JS::HandleObject wrapper,
JS::HandleObject target,
JS::MutableHandleObject protop);
virtual void preserveWrapper(JSObject* target) override;
virtual JSObject* createHolder(JSContext* cx, JSObject* wrapper) override;
static DOMXrayTraits singleton;
protected:
virtual const JSClass* getExpandoClass(
JSContext* cx, JS::HandleObject target) const override;
};
class JSXrayTraits : public XrayTraits {
public:
static const XrayType Type = XrayForJSObject;
virtual bool resolveOwnProperty(
JSContext* cx, JS::HandleObject wrapper, JS::HandleObject target,
JS::HandleObject holder, JS::HandleId id,
JS::MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> desc) override;
bool delete_(JSContext* cx, JS::HandleObject wrapper, JS::HandleId id,
JS::ObjectOpResult& result);
bool defineProperty(
JSContext* cx, JS::HandleObject wrapper, JS::HandleId id,
JS::Handle<JS::PropertyDescriptor> desc,
JS::Handle<mozilla::Maybe<JS::PropertyDescriptor>> existingDesc,
JS::Handle<JSObject*> existingHolder, JS::ObjectOpResult& result,
bool* defined);
virtual bool enumerateNames(JSContext* cx, JS::HandleObject wrapper,
unsigned flags, JS::MutableHandleIdVector props);
static bool call(JSContext* cx, JS::HandleObject wrapper,
const JS::CallArgs& args, const js::Wrapper& baseInstance) {
JSXrayTraits& self = JSXrayTraits::singleton;
JS::RootedObject holder(cx, self.ensureHolder(cx, wrapper));
if (!holder) {
return false;
}
JSProtoKey key = xpc::JSXrayTraits::getProtoKey(holder);
if (key == JSProto_Function || key == JSProto_BoundFunction) {
return baseInstance.call(cx, wrapper, args);
}
JS::RootedValue v(cx, JS::ObjectValue(*wrapper));
js::ReportIsNotFunction(cx, v);
return false;
}
static bool construct(JSContext* cx, JS::HandleObject wrapper,
const JS::CallArgs& args,
const js::Wrapper& baseInstance);
bool getPrototype(JSContext* cx, JS::HandleObject wrapper,
JS::HandleObject target, JS::MutableHandleObject protop) {
JS::RootedObject holder(cx, ensureHolder(cx, wrapper));
if (!holder) {
return false;
}
JSProtoKey key = getProtoKey(holder);
if (isPrototype(holder)) {
JSProtoKey protoKey = js::InheritanceProtoKeyForStandardClass(key);
if (protoKey == JSProto_Null) {
protop.set(nullptr);
return true;
}
key = protoKey;
}
{
JSAutoRealm ar(cx, target);
if (!JS_GetClassPrototype(cx, key, protop)) {
return false;
}
}
return JS_WrapObject(cx, protop);
}
virtual void preserveWrapper(JSObject* target) override {
// In the case of pure JS objects, there is no underlying object, and
// the target is the canonical representation of state. If it gets
// collected, then expandos and such should be collected too. So there's
// nothing to do here.
}
enum {
SLOT_PROTOKEY = HOLDER_SHARED_SLOT_COUNT,
SLOT_ISPROTOTYPE,
SLOT_CONSTRUCTOR_FOR,
SLOT_COUNT
};
virtual JSObject* createHolder(JSContext* cx, JSObject* wrapper) override;
static JSProtoKey getProtoKey(JSObject* holder) {
int32_t key = JS::GetReservedSlot(holder, SLOT_PROTOKEY).toInt32();
return static_cast<JSProtoKey>(key);
}
static bool isPrototype(JSObject* holder) {
return JS::GetReservedSlot(holder, SLOT_ISPROTOTYPE).toBoolean();
}
static JSProtoKey constructorFor(JSObject* holder) {
int32_t key = JS::GetReservedSlot(holder, SLOT_CONSTRUCTOR_FOR).toInt32();
return static_cast<JSProtoKey>(key);
}
// Operates in the wrapper compartment.
static bool getOwnPropertyFromWrapperIfSafe(
JSContext* cx, JS::HandleObject wrapper, JS::HandleId id,
JS::MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> desc);
// Like the above, but operates in the target compartment. wrapperGlobal is
// the caller's global (must be in the wrapper compartment).
static bool getOwnPropertyFromTargetIfSafe(
JSContext* cx, JS::HandleObject target, JS::HandleObject wrapper,
JS::HandleObject wrapperGlobal, JS::HandleId id,
JS::MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> desc);
static const JSClass HolderClass;
static JSXrayTraits singleton;
};
// These traits are used when the target is not Xrayable and we therefore want
// to make it opaque modulo the usual Xray machinery (like expandos and
// .wrappedJSObject).
class OpaqueXrayTraits : public XrayTraits {
public:
static const XrayType Type = XrayForOpaqueObject;
virtual bool resolveOwnProperty(
JSContext* cx, JS::HandleObject wrapper, JS::HandleObject target,
JS::HandleObject holder, JS::HandleId id,
JS::MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> desc) override;
bool defineProperty(
JSContext* cx, JS::HandleObject wrapper, JS::HandleId id,
JS::Handle<JS::PropertyDescriptor> desc,
JS::Handle<mozilla::Maybe<JS::PropertyDescriptor>> existingDesc,
JS::Handle<JSObject*> existingHolder, JS::ObjectOpResult& result,
bool* defined) {
*defined = false;
return true;
}
virtual bool enumerateNames(JSContext* cx, JS::HandleObject wrapper,
unsigned flags, JS::MutableHandleIdVector props) {
return true;
}
static bool call(JSContext* cx, JS::HandleObject wrapper,
const JS::CallArgs& args, const js::Wrapper& baseInstance) {
JS::RootedValue v(cx, JS::ObjectValue(*wrapper));
js::ReportIsNotFunction(cx, v);
return false;
}
static bool construct(JSContext* cx, JS::HandleObject wrapper,
const JS::CallArgs& args,
const js::Wrapper& baseInstance) {
JS::RootedValue v(cx, JS::ObjectValue(*wrapper));
js::ReportIsNotFunction(cx, v);
return false;
}
bool getPrototype(JSContext* cx, JS::HandleObject wrapper,
JS::HandleObject target, JS::MutableHandleObject protop) {
// Opaque wrappers just get targetGlobal.Object.prototype as their
// prototype. This is preferable to using a null prototype because it
// lets things like |toString| and |__proto__| work.
{
JSAutoRealm ar(cx, target);
if (!JS_GetClassPrototype(cx, JSProto_Object, protop)) {
return false;
}
}
return JS_WrapObject(cx, protop);
}
static bool getBuiltinClass(JSContext* cx, JS::HandleObject wrapper,
const js::Wrapper& baseInstance,
js::ESClass* cls) {
*cls = js::ESClass::Other;
return true;
}
static const char* className(JSContext* cx, JS::HandleObject wrapper,
const js::Wrapper& baseInstance) {
return "Opaque";
}
virtual void preserveWrapper(JSObject* target) override {}
virtual JSObject* createHolder(JSContext* cx, JSObject* wrapper) override {
return JS_NewObjectWithGivenProto(cx, &HolderClass, nullptr);
}
static OpaqueXrayTraits singleton;
};
XrayType GetXrayType(JSObject* obj);
XrayTraits* GetXrayTraits(JSObject* obj);
template <typename Base, typename Traits>
class XrayWrapper : public Base {
static_assert(std::is_base_of_v<js::BaseProxyHandler, Base>,
"Base *must* derive from js::BaseProxyHandler");
public:
constexpr explicit XrayWrapper(unsigned flags)
: Base(flags | WrapperFactory::IS_XRAY_WRAPPER_FLAG,
/* aHasPrototype = */ true){};
/* Standard internal methods. */
virtual bool getOwnPropertyDescriptor(
JSContext* cx, JS::Handle<JSObject*> wrapper, JS::Handle<jsid> id,
JS::MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> desc)
const override;
virtual bool defineProperty(JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::Handle<jsid> id,
JS::Handle<JS::PropertyDescriptor> desc,
JS::ObjectOpResult& result) const override;
virtual bool ownPropertyKeys(JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::MutableHandleIdVector props) const override;
virtual bool delete_(JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::Handle<jsid> id,
JS::ObjectOpResult& result) const override;
virtual bool enumerate(JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::MutableHandleIdVector props) const override;
virtual bool getPrototype(JSContext* cx, JS::HandleObject wrapper,
JS::MutableHandleObject protop) const override;
virtual bool setPrototype(JSContext* cx, JS::HandleObject wrapper,
JS::HandleObject proto,
JS::ObjectOpResult& result) const override;
virtual bool getPrototypeIfOrdinary(
JSContext* cx, JS::HandleObject wrapper, bool* isOrdinary,
JS::MutableHandleObject protop) const override;
virtual bool setImmutablePrototype(JSContext* cx, JS::HandleObject wrapper,
bool* succeeded) const override;
virtual bool preventExtensions(JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::ObjectOpResult& result) const override;
virtual bool isExtensible(JSContext* cx, JS::Handle<JSObject*> wrapper,
bool* extensible) const override;
virtual bool has(JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::Handle<jsid> id, bool* bp) const override;
virtual bool get(JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::HandleValue receiver, JS::Handle<jsid> id,
JS::MutableHandle<JS::Value> vp) const override;
virtual bool set(JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::Handle<jsid> id, JS::Handle<JS::Value> v,
JS::Handle<JS::Value> receiver,
JS::ObjectOpResult& result) const override;
virtual bool call(JSContext* cx, JS::Handle<JSObject*> wrapper,
const JS::CallArgs& args) const override;
virtual bool construct(JSContext* cx, JS::Handle<JSObject*> wrapper,
const JS::CallArgs& args) const override;
/* SpiderMonkey extensions. */
virtual bool hasOwn(JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::Handle<jsid> id, bool* bp) const override;
virtual bool getOwnEnumerablePropertyKeys(
JSContext* cx, JS::Handle<JSObject*> wrapper,
JS::MutableHandleIdVector props) const override;
virtual bool getBuiltinClass(JSContext* cx, JS::HandleObject wapper,
js::ESClass* cls) const override;
virtual const char* className(JSContext* cx,
JS::HandleObject proxy) const override;
static const XrayWrapper singleton;
protected:
bool getPropertyKeys(JSContext* cx, JS::Handle<JSObject*> wrapper,
unsigned flags, JS::MutableHandleIdVector props) const;
};
#define PermissiveXrayDOM \
xpc::XrayWrapper<js::CrossCompartmentWrapper, xpc::DOMXrayTraits>
#define PermissiveXrayJS \
xpc::XrayWrapper<js::CrossCompartmentWrapper, xpc::JSXrayTraits>
#define PermissiveXrayOpaque \
xpc::XrayWrapper<js::CrossCompartmentWrapper, xpc::OpaqueXrayTraits>
extern template class PermissiveXrayDOM;
extern template class PermissiveXrayJS;
extern template class PermissiveXrayOpaque;
/*
* Slots for Xray expando objects. See comments in XrayWrapper.cpp for details
* of how these get used; we mostly want the value of JSSLOT_EXPANDO_COUNT here.
*/
enum ExpandoSlots {
JSSLOT_EXPANDO_NEXT = 0,
JSSLOT_EXPANDO_ORIGIN,
JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER,
JSSLOT_EXPANDO_PROTOTYPE,
JSSLOT_EXPANDO_COUNT
};
extern const JSClassOps XrayExpandoObjectClassOps;
/*
* Clear the given slot on all Xray expandos for the given object.
*
* No-op when called on non-main threads (where Xrays don't exist).
*/
void ClearXrayExpandoSlots(JSObject* target, size_t slotIndex);
/*
* Ensure the given wrapper has an expando object and return it. This can
* return null on failure. Will only be called when "wrapper" is an Xray for a
* DOM object.
*/
JSObject* EnsureXrayExpandoObject(JSContext* cx, JS::HandleObject wrapper);
// Information about xrays for use by the JITs.
extern JS::XrayJitInfo gXrayJitInfo;
} // namespace xpc
#endif