Ejemplo n.º 1
0
bool
JSCompartment::wrap(JSContext* cx, MutableHandleString strp)
{
    MOZ_ASSERT(!cx->runtime()->isAtomsCompartment(this));
    MOZ_ASSERT(cx->compartment() == this);

    /* If the string is already in this compartment, we are done. */
    JSString* str = strp;
    if (str->zoneFromAnyThread() == zone())
        return true;

    /* If the string is an atom, we don't have to copy. */
    if (str->isAtom()) {
        MOZ_ASSERT(str->isPermanentAtom() || str->zone()->isAtomsZone());
        return true;
    }

    /* Check the cache. */
    RootedValue key(cx, StringValue(str));
    if (WrapperMap::Ptr p = crossCompartmentWrappers.lookup(CrossCompartmentKey(key))) {
        strp.set(p->value().get().toString());
        return true;
    }

    /* No dice. Make a copy, and cache it. */
    JSString* copy = CopyStringPure(cx, str);
    if (!copy)
        return false;
    if (!putWrapper(cx, CrossCompartmentKey(key), StringValue(copy)))
        return false;

    strp.set(copy);
    return true;
}
Ejemplo n.º 2
0
JSAtom *
js::ToAtom(ExclusiveContext *cx, typename MaybeRooted<Value, allowGC>::HandleType v)
{
    if (!v.isString())
        return ToAtomSlow<allowGC>(cx, v);

    JSString *str = v.toString();
    if (str->isAtom())
        return &str->asAtom();

    return AtomizeString(cx, str);
}
Ejemplo n.º 3
0
bool
JSCompartment::wrap(JSContext *cx, JSString **strp)
{
    JS_ASSERT(!cx->runtime()->isAtomsCompartment(this));
    JS_ASSERT(cx->compartment() == this);

    /* If the string is already in this compartment, we are done. */
    JSString *str = *strp;
    if (str->zone() == zone())
        return true;

    /* If the string is an atom, we don't have to copy. */
    if (str->isAtom()) {
        JS_ASSERT(cx->runtime()->isAtomsZone(str->zone()));
        return true;
    }

    /* Check the cache. */
    RootedValue key(cx, StringValue(str));
    if (WrapperMap::Ptr p = crossCompartmentWrappers.lookup(key)) {
        *strp = p->value().get().toString();
        return true;
    }

    /* No dice. Make a copy, and cache it. */
    Rooted<JSLinearString *> linear(cx, str->ensureLinear(cx));
    if (!linear)
        return false;
    JSString *copy = js_NewStringCopyN<CanGC>(cx, linear->chars(),
                                              linear->length());
    if (!copy)
        return false;
    if (!putWrapper(key, StringValue(copy)))
        return false;

    if (linear->zone()->isGCMarking()) {
        /*
         * All string wrappers are dropped when collection starts, but we
         * just created a new one.  Mark the wrapped string to stop it being
         * finalized, because if it was then the pointer in this
         * compartment's wrapper map would be left dangling.
         */
        JSString *tmp = linear;
        MarkStringUnbarriered(&cx->runtime()->gcMarker, &tmp, "wrapped string");
        JS_ASSERT(tmp == linear);
    }

    *strp = copy;
    return true;
}
Ejemplo n.º 4
0
bool
JSCompartment::wrap(JSContext *cx, JSString **strp)
{
    JS_ASSERT(!cx->runtime()->isAtomsCompartment(this));
    JS_ASSERT(cx->compartment() == this);

    /* If the string is already in this compartment, we are done. */
    JSString *str = *strp;
    if (str->zone() == zone())
        return true;

    /* If the string is an atom, we don't have to copy. */
    if (str->isAtom()) {
        JS_ASSERT(cx->runtime()->isAtomsZone(str->zone()));
        return true;
    }

    /* Check the cache. */
    RootedValue key(cx, StringValue(str));
    if (WrapperMap::Ptr p = crossCompartmentWrappers.lookup(key)) {
        *strp = p->value().get().toString();
        return true;
    }

    /*
     * No dice. Make a copy, and cache it. Directly allocate the copy in the
     * destination compartment, rather than first flattening it (and possibly
     * allocating in source compartment), because we don't know whether the
     * flattening will pay off later.
     */
    JSString *copy;
    if (str->hasPureChars()) {
        copy = js_NewStringCopyN<CanGC>(cx, str->pureChars(), str->length());
    } else {
        ScopedJSFreePtr<jschar> copiedChars;
        if (!str->copyNonPureCharsZ(cx, copiedChars))
            return false;
        copy = js_NewString<CanGC>(cx, copiedChars.forget(), str->length());
    }

    if (!copy)
        return false;
    if (!putWrapper(cx, key, StringValue(copy)))
        return false;

    *strp = copy;
    return true;
}
Ejemplo n.º 5
0
    void generateStringPath(Assembler &masm)
    {
        const ValueRemat &lvr = ic.lvr;
        const ValueRemat &rvr = ic.rvr;

        JS_ASSERT_IF(lvr.isConstant(), lvr.isType(JSVAL_TYPE_STRING));
        JS_ASSERT_IF(rvr.isConstant(), rvr.isType(JSVAL_TYPE_STRING));

        if (!lvr.isType(JSVAL_TYPE_STRING)) {
            Jump lhsFail = masm.testString(Assembler::NotEqual, lvr.typeReg());
            linkToStub(lhsFail);
        }
        
        if (!rvr.isType(JSVAL_TYPE_STRING)) {
            Jump rhsFail = masm.testString(Assembler::NotEqual, rvr.typeReg());
            linkToStub(rhsFail);
        }

        RegisterID tmp = ic.tempReg;
        
        /* JSString::isAtom === (lengthAndFlags & ATOM_MASK == 0) */
        JS_STATIC_ASSERT(JSString::ATOM_FLAGS == 0);
        Imm32 atomMask(JSString::ATOM_MASK);
        
        masm.load32(Address(lvr.dataReg(), JSString::offsetOfLengthAndFlags()), tmp);
        Jump lhsNotAtomized = masm.branchTest32(Assembler::NonZero, tmp, atomMask);
        linkToStub(lhsNotAtomized);

        if (!rvr.isConstant()) {
            masm.load32(Address(rvr.dataReg(), JSString::offsetOfLengthAndFlags()), tmp);
            Jump rhsNotAtomized = masm.branchTest32(Assembler::NonZero, tmp, atomMask);
            linkToStub(rhsNotAtomized);
        }

        if (rvr.isConstant()) {
            JSString *str = rvr.value().toString();
            JS_ASSERT(str->isAtom());
            Jump test = masm.branchPtr(ic.cond, lvr.dataReg(), ImmPtr(str));
            linkTrue(test);
        } else {
            Jump test = masm.branchPtr(ic.cond, lvr.dataReg(), rvr.dataReg());
            linkTrue(test);
        }

        Jump fallthrough = masm.jump();
        linkFalse(fallthrough);
    }
Ejemplo n.º 6
0
JSAtom*
js::ToAtom(ExclusiveContext* cx, typename MaybeRooted<Value, allowGC>::HandleType v)
{
    if (!v.isString())
        return ToAtomSlow<allowGC>(cx, v);

    JSString* str = v.toString();
    if (str->isAtom())
        return &str->asAtom();

    JSAtom* atom = AtomizeString(cx, str);
    if (!atom && !allowGC) {
        MOZ_ASSERT_IF(cx->isJSContext(), cx->asJSContext()->isThrowingOutOfMemory());
        cx->recoverFromOutOfMemory();
    }
    return atom;
}
Ejemplo n.º 7
0
JSAtom *
js::ToAtom(ExclusiveContext *cx, typename MaybeRooted<Value, allowGC>::HandleType v)
{
    if (!v.isString()) {
        JSString *str = js::ToStringSlow<allowGC>(cx, v);
        if (!str)
            return NULL;
        JS::Anchor<JSString *> anchor(str);
        return AtomizeString<allowGC>(cx, str);
    }

    JSString *str = v.toString();
    if (str->isAtom())
        return &str->asAtom();

    JS::Anchor<JSString *> anchor(str);
    return AtomizeString<allowGC>(cx, str);
}
Ejemplo n.º 8
0
bool
JSCompartment::wrap(JSContext *cx, MutableHandleValue vp, HandleObject existingArg)
{
    JS_ASSERT(cx->compartment() == this);
    JS_ASSERT(this != rt->atomsCompartment);
    JS_ASSERT_IF(existingArg, existingArg->compartment() == cx->compartment());
    JS_ASSERT_IF(existingArg, vp.isObject());
    JS_ASSERT_IF(existingArg, IsDeadProxyObject(existingArg));

    unsigned flags = 0;

    JS_CHECK_CHROME_RECURSION(cx, return false);

    AutoDisableProxyCheck adpc(rt);

    /* Only GC things have to be wrapped or copied. */
    if (!vp.isMarkable())
        return true;

    if (vp.isString()) {
        JSString *str = vp.toString();

        /* If the string is already in this compartment, we are done. */
        if (str->zone() == zone())
            return true;

        /* If the string is an atom, we don't have to copy. */
        if (str->isAtom()) {
            JS_ASSERT(str->zone() == cx->runtime()->atomsCompartment->zone());
            return true;
        }
    }

    /*
     * Wrappers should really be parented to the wrapped parent of the wrapped
     * object, but in that case a wrapped global object would have a NULL
     * parent without being a proper global object (JSCLASS_IS_GLOBAL). Instead,
     * we parent all wrappers to the global object in their home compartment.
     * This loses us some transparency, and is generally very cheesy.
     */
    HandleObject global = cx->global();

    /* Unwrap incoming objects. */
    if (vp.isObject()) {
        RootedObject obj(cx, &vp.toObject());

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);

        /* Translate StopIteration singleton. */
        if (obj->is<StopIterationObject>())
            return js_FindClassObject(cx, JSProto_StopIteration, vp);

        /* Unwrap the object, but don't unwrap outer windows. */
        obj = UncheckedUnwrap(obj, /* stopAtOuter = */ true, &flags);

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);

        if (cx->runtime()->preWrapObjectCallback) {
            obj = cx->runtime()->preWrapObjectCallback(cx, global, obj, flags);
            if (!obj)
                return false;
        }

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);
        vp.setObject(*obj);

#ifdef DEBUG
        {
            JSObject *outer = GetOuterObject(cx, obj);
            JS_ASSERT(outer && outer == obj);
        }
#endif
    }

    RootedValue key(cx, vp);

    /* If we already have a wrapper for this value, use it. */
    if (WrapperMap::Ptr p = crossCompartmentWrappers.lookup(key)) {
        vp.set(p->value);
        if (vp.isObject()) {
            DebugOnly<JSObject *> obj = &vp.toObject();
            JS_ASSERT(obj->isCrossCompartmentWrapper());
            JS_ASSERT(obj->getParent() == global);
        }
        return true;
    }

    if (vp.isString()) {
        Rooted<JSLinearString *> str(cx, vp.toString()->ensureLinear(cx));
        if (!str)
            return false;

        JSString *wrapped = js_NewStringCopyN<CanGC>(cx, str->chars(), str->length());
        if (!wrapped)
            return false;

        vp.setString(wrapped);
        if (!putWrapper(key, vp))
            return false;

        if (str->zone()->isGCMarking()) {
            /*
             * All string wrappers are dropped when collection starts, but we
             * just created a new one.  Mark the wrapped string to stop it being
             * finalized, because if it was then the pointer in this
             * compartment's wrapper map would be left dangling.
             */
            JSString *tmp = str;
            MarkStringUnbarriered(&rt->gcMarker, &tmp, "wrapped string");
            JS_ASSERT(tmp == str);
        }

        return true;
    }

    RootedObject proto(cx, Proxy::LazyProto);
    RootedObject obj(cx, &vp.toObject());
    RootedObject existing(cx, existingArg);
    if (existing) {
        /* Is it possible to reuse |existing|? */
        if (!existing->getTaggedProto().isLazy() ||
            existing->getClass() != &ObjectProxyClass ||
            existing->getParent() != global ||
            obj->isCallable())
        {
            existing = NULL;
        }
    }

    /*
     * We hand in the original wrapped object into the wrap hook to allow
     * the wrap hook to reason over what wrappers are currently applied
     * to the object.
     */
    RootedObject wrapper(cx);
    wrapper = cx->runtime()->wrapObjectCallback(cx, existing, obj, proto, global, flags);
    if (!wrapper)
        return false;

    // We maintain the invariant that the key in the cross-compartment wrapper
    // map is always directly wrapped by the value.
    JS_ASSERT(Wrapper::wrappedObject(wrapper) == &key.get().toObject());

    vp.setObject(*wrapper);
    return putWrapper(key, vp);
}
Ejemplo n.º 9
0
bool
JSCompartment::wrap(JSContext *cx, Value *vp, JSObject *existing)
{
    JS_ASSERT(cx->compartment == this);
    JS_ASSERT_IF(existing, existing->compartment() == cx->compartment);
    JS_ASSERT_IF(existing, vp->isObject());
    JS_ASSERT_IF(existing, IsDeadProxyObject(existing));

    unsigned flags = 0;

    JS_CHECK_CHROME_RECURSION(cx, return false);

#ifdef DEBUG
    struct AutoDisableProxyCheck {
        JSRuntime *runtime;
        AutoDisableProxyCheck(JSRuntime *rt) : runtime(rt) {
            runtime->gcDisableStrictProxyCheckingCount++;
        }
        ~AutoDisableProxyCheck() { runtime->gcDisableStrictProxyCheckingCount--; }
    } adpc(rt);
#endif

    /* Only GC things have to be wrapped or copied. */
    if (!vp->isMarkable())
        return true;

    if (vp->isString()) {
        JSString *str = vp->toString();

        /* If the string is already in this compartment, we are done. */
        if (str->compartment() == this)
            return true;

        /* If the string is an atom, we don't have to copy. */
        if (str->isAtom()) {
            JS_ASSERT(str->compartment() == cx->runtime->atomsCompartment);
            return true;
        }
    }

    /*
     * Wrappers should really be parented to the wrapped parent of the wrapped
     * object, but in that case a wrapped global object would have a NULL
     * parent without being a proper global object (JSCLASS_IS_GLOBAL). Instead,
     * we parent all wrappers to the global object in their home compartment.
     * This loses us some transparency, and is generally very cheesy.
     */
    HandleObject global = cx->global();

    /* Unwrap incoming objects. */
    if (vp->isObject()) {
        Rooted<JSObject*> obj(cx, &vp->toObject());

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);

        /* Translate StopIteration singleton. */
        if (obj->isStopIteration()) {
            RootedValue vvp(cx, *vp);
            bool result = js_FindClassObject(cx, JSProto_StopIteration, &vvp);
            *vp = vvp;
            return result;
        }

        /* Unwrap the object, but don't unwrap outer windows. */
        obj = UnwrapObject(&vp->toObject(), /* stopAtOuter = */ true, &flags);

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);

        if (cx->runtime->preWrapObjectCallback) {
            obj = cx->runtime->preWrapObjectCallback(cx, global, obj, flags);
            if (!obj)
                return false;
        }

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);
        vp->setObject(*obj);

#ifdef DEBUG
        {
            JSObject *outer = GetOuterObject(cx, obj);
            JS_ASSERT(outer && outer == obj);
        }
#endif
    }

    RootedValue key(cx, *vp);

    /* If we already have a wrapper for this value, use it. */
    if (WrapperMap::Ptr p = crossCompartmentWrappers.lookup(key)) {
        *vp = p->value;
        if (vp->isObject()) {
            RootedObject obj(cx, &vp->toObject());
            JS_ASSERT(obj->isCrossCompartmentWrapper());
            JS_ASSERT(obj->getParent() == global);
        }
        return true;
    }

    if (vp->isString()) {
        RootedValue orig(cx, *vp);
        JSStableString *str = vp->toString()->ensureStable(cx);
        if (!str)
            return false;
        JSString *wrapped = js_NewStringCopyN(cx, str->chars().get(), str->length());
        if (!wrapped)
            return false;
        vp->setString(wrapped);
        return crossCompartmentWrappers.put(orig, *vp);
    }

    RootedObject obj(cx, &vp->toObject());

    JSObject *proto = Proxy::LazyProto;
    if (existing) {
        /* Is it possible to reuse |existing|? */
        if (!existing->getTaggedProto().isLazy() ||
            existing->getClass() != &ObjectProxyClass ||
            existing->getParent() != global ||
            obj->isCallable())
        {
            existing = NULL;
        }
    }

    /*
     * We hand in the original wrapped object into the wrap hook to allow
     * the wrap hook to reason over what wrappers are currently applied
     * to the object.
     */
    RootedObject wrapper(cx);
    wrapper = cx->runtime->wrapObjectCallback(cx, existing, obj, proto, global, flags);
    if (!wrapper)
        return false;

    // We maintain the invariant that the key in the cross-compartment wrapper
    // map is always directly wrapped by the value.
    JS_ASSERT(Wrapper::wrappedObject(wrapper) == &key.get().toObject());

    vp->setObject(*wrapper);

    if (!crossCompartmentWrappers.put(key, *vp))
        return false;

    return true;
}
bool
JSCompartment::wrap(JSContext *cx, Value *vp)
{
    JS_ASSERT(cx->compartment == this);

    unsigned flags = 0;

    JS_CHECK_RECURSION(cx, return false);

    /* Only GC things have to be wrapped or copied. */
    if (!vp->isMarkable())
        return true;

    if (vp->isString()) {
        JSString *str = vp->toString();

        /* If the string is already in this compartment, we are done. */
        if (str->compartment() == this)
            return true;

        /* If the string is an atom, we don't have to copy. */
        if (str->isAtom()) {
            JS_ASSERT(str->compartment() == cx->runtime->atomsCompartment);
            return true;
        }
    }

    /*
     * Wrappers should really be parented to the wrapped parent of the wrapped
     * object, but in that case a wrapped global object would have a NULL
     * parent without being a proper global object (JSCLASS_IS_GLOBAL). Instead,
     * we parent all wrappers to the global object in their home compartment.
     * This loses us some transparency, and is generally very cheesy.
     */
    JSObject *global;
    if (cx->hasfp()) {
        global = &cx->fp()->scopeChain().global();
    } else {
        global = JS_ObjectToInnerObject(cx, cx->globalObject);
        if (!global)
            return false;
    }

    /* Unwrap incoming objects. */
    if (vp->isObject()) {
        JSObject *obj = &vp->toObject();

        /* If the object is already in this compartment, we are done. */
        if (obj->compartment() == this)
            return true;

        /* Translate StopIteration singleton. */
        if (obj->isStopIteration())
            return js_FindClassObject(cx, NULL, JSProto_StopIteration, vp);

        /* Don't unwrap an outer window proxy. */
        if (!obj->getClass()->ext.innerObject) {
            obj = UnwrapObject(&vp->toObject(), true, &flags);
            vp->setObject(*obj);
            if (obj->compartment() == this)
                return true;

            if (cx->runtime->preWrapObjectCallback) {
                obj = cx->runtime->preWrapObjectCallback(cx, global, obj, flags);
                if (!obj)
                    return false;
            }

            vp->setObject(*obj);
            if (obj->compartment() == this)
                return true;
        } else {
            if (cx->runtime->preWrapObjectCallback) {
                obj = cx->runtime->preWrapObjectCallback(cx, global, obj, flags);
                if (!obj)
                    return false;
            }

            JS_ASSERT(!obj->isWrapper() || obj->getClass()->ext.innerObject);
            vp->setObject(*obj);
        }

#ifdef DEBUG
        {
            JSObject *outer = obj;
            OBJ_TO_OUTER_OBJECT(cx, outer);
            JS_ASSERT(outer && outer == obj);
        }
#endif
    }

    /* If we already have a wrapper for this value, use it. */
    if (WrapperMap::Ptr p = crossCompartmentWrappers.lookup(*vp)) {
        *vp = p->value;
        if (vp->isObject()) {
            JSObject *obj = &vp->toObject();
            JS_ASSERT(obj->isCrossCompartmentWrapper());
            if (global->getClass() != &dummy_class && obj->getParent() != global) {
                do {
                    if (!obj->setParent(cx, global))
                        return false;
                    obj = obj->getProto();
                } while (obj && obj->isCrossCompartmentWrapper());
            }
        }
        return true;
    }

    if (vp->isString()) {
        Value orig = *vp;
        JSString *str = vp->toString();
        const jschar *chars = str->getChars(cx);
        if (!chars)
            return false;
        JSString *wrapped = js_NewStringCopyN(cx, chars, str->length());
        if (!wrapped)
            return false;
        vp->setString(wrapped);
        return crossCompartmentWrappers.put(orig, *vp);
    }

    JSObject *obj = &vp->toObject();

    /*
     * Recurse to wrap the prototype. Long prototype chains will run out of
     * stack, causing an error in CHECK_RECURSE.
     *
     * Wrapping the proto before creating the new wrapper and adding it to the
     * cache helps avoid leaving a bad entry in the cache on OOM. But note that
     * if we wrapped both proto and parent, we would get infinite recursion
     * here (since Object.prototype->parent->proto leads to Object.prototype
     * itself).
     */
    JSObject *proto = obj->getProto();
    if (!wrap(cx, &proto))
        return false;

    /*
     * We hand in the original wrapped object into the wrap hook to allow
     * the wrap hook to reason over what wrappers are currently applied
     * to the object.
     */
    JSObject *wrapper = cx->runtime->wrapObjectCallback(cx, obj, proto, global, flags);
    if (!wrapper)
        return false;

    vp->setObject(*wrapper);

    if (wrapper->getProto() != proto && !SetProto(cx, wrapper, proto, false))
        return false;

    if (!crossCompartmentWrappers.put(GetProxyPrivate(wrapper), *vp))
        return false;

    if (!wrapper->setParent(cx, global))
        return false;
    return true;
}
Ejemplo n.º 11
0
bool
JSCompartment::wrap(JSContext *cx, Value *vp)
{
    JS_ASSERT(cx->compartment == this);

    unsigned flags = 0;

    JS_CHECK_RECURSION(cx, return false);

#ifdef DEBUG
    struct AutoDisableProxyCheck {
        JSRuntime *runtime;
        AutoDisableProxyCheck(JSRuntime *rt) : runtime(rt) {
            runtime->gcDisableStrictProxyCheckingCount++;
        }
        ~AutoDisableProxyCheck() { runtime->gcDisableStrictProxyCheckingCount--; }
    } adpc(rt);
#endif

    /* Only GC things have to be wrapped or copied. */
    if (!vp->isMarkable())
        return true;

    if (vp->isString()) {
        JSString *str = vp->toString();

        /* If the string is already in this compartment, we are done. */
        if (str->compartment() == this)
            return true;

        /* If the string is an atom, we don't have to copy. */
        if (str->isAtom()) {
            JS_ASSERT(str->compartment() == cx->runtime->atomsCompartment);
            return true;
        }
    }

    /*
     * Wrappers should really be parented to the wrapped parent of the wrapped
     * object, but in that case a wrapped global object would have a NULL
     * parent without being a proper global object (JSCLASS_IS_GLOBAL). Instead,
     * we parent all wrappers to the global object in their home compartment.
     * This loses us some transparency, and is generally very cheesy.
     */
    HandleObject global = cx->global();

    /* Unwrap incoming objects. */
    if (vp->isObject()) {
        Rooted<JSObject*> obj(cx, &vp->toObject());

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);

        /* Translate StopIteration singleton. */
        if (obj->isStopIteration()) {
            RootedValue vvp(cx, *vp);
            bool result = js_FindClassObject(cx, JSProto_StopIteration, &vvp);
            *vp = vvp;
            return result;
        }

        /* Unwrap the object, but don't unwrap outer windows. */
        obj = UnwrapObject(&vp->toObject(), /* stopAtOuter = */ true, &flags);

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);

        if (cx->runtime->preWrapObjectCallback) {
            obj = cx->runtime->preWrapObjectCallback(cx, global, obj, flags);
            if (!obj)
                return false;
        }

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);
        vp->setObject(*obj);

#ifdef DEBUG
        {
            JSObject *outer = GetOuterObject(cx, obj);
            JS_ASSERT(outer && outer == obj);
        }
#endif
    }

    RootedValue key(cx, *vp);

    /* If we already have a wrapper for this value, use it. */
    if (WrapperMap::Ptr p = crossCompartmentWrappers.lookup(key)) {
        *vp = p->value;
        if (vp->isObject()) {
            RootedObject obj(cx, &vp->toObject());
            JS_ASSERT(obj->isCrossCompartmentWrapper());
            if (obj->getParent() != global) {
                do {
                    if (!JSObject::setParent(cx, obj, global))
                        return false;
                    obj = obj->getProto();
                } while (obj && obj->isCrossCompartmentWrapper());
            }
        }
        return true;
    }

    if (vp->isString()) {
        RootedValue orig(cx, *vp);
        JSString *str = vp->toString();
        const jschar *chars = str->getChars(cx);
        if (!chars)
            return false;
        JSString *wrapped = js_NewStringCopyN(cx, chars, str->length());
        if (!wrapped)
            return false;
        vp->setString(wrapped);
        return crossCompartmentWrappers.put(orig, *vp);
    }

    RootedObject obj(cx, &vp->toObject());

    /*
     * Recurse to wrap the prototype. Long prototype chains will run out of
     * stack, causing an error in CHECK_RECURSE.
     *
     * Wrapping the proto before creating the new wrapper and adding it to the
     * cache helps avoid leaving a bad entry in the cache on OOM. But note that
     * if we wrapped both proto and parent, we would get infinite recursion
     * here (since Object.prototype->parent->proto leads to Object.prototype
     * itself).
     */
    RootedObject proto(cx, obj->getProto());
    if (!wrap(cx, proto.address()))
        return false;

    /*
     * We hand in the original wrapped object into the wrap hook to allow
     * the wrap hook to reason over what wrappers are currently applied
     * to the object.
     */
    RootedObject wrapper(cx, cx->runtime->wrapObjectCallback(cx, obj, proto, global, flags));
    if (!wrapper)
        return false;

    // We maintain the invariant that the key in the cross-compartment wrapper
    // map is always directly wrapped by the value.
    JS_ASSERT(Wrapper::wrappedObject(wrapper) == &key.get().toObject());

    vp->setObject(*wrapper);

    if (!crossCompartmentWrappers.put(key, *vp))
        return false;

    return true;
}