cosmopolitan/third_party/quickjs/proxy.c

/*
 * QuickJS Javascript Engine
 *
 * Copyright (c) 2017-2021 Fabrice Bellard
 * Copyright (c) 2017-2021 Charlie Gordon
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "libc/assert.h"
#include "third_party/quickjs/internal.h"

asm(".ident\t\"\\n\\n\
QuickJS (MIT License)\\n\
Copyright (c) 2017-2021 Fabrice Bellard\\n\
Copyright (c) 2017-2021 Charlie Gordon\"");
asm(".include \"libc/disclaimer.inc\"");
/* clang-format off */

static void js_proxy_finalizer(JSRuntime *rt, JSValue val)
{
    JSProxyData *s = JS_GetOpaque(val, JS_CLASS_PROXY);
    if (s) {
        JS_FreeValueRT(rt, s->target);
        JS_FreeValueRT(rt, s->handler);
        js_free_rt(rt, s);
    }
}

static void js_proxy_mark(JSRuntime *rt, JSValueConst val,
                          JS_MarkFunc *mark_func)
{
    JSProxyData *s = JS_GetOpaque(val, JS_CLASS_PROXY);
    if (s) {
        JS_MarkValue(rt, s->target, mark_func);
        JS_MarkValue(rt, s->handler, mark_func);
    }
}

static JSProxyData *get_proxy_method(JSContext *ctx, JSValue *pmethod,
                                     JSValueConst obj, JSAtom name)
{
    JSProxyData *s = JS_GetOpaque(obj, JS_CLASS_PROXY);
    JSValue method;
    /* safer to test recursion in all proxy methods */
    if (js_check_stack_overflow(ctx->rt, 0)) {
        JS_ThrowStackOverflow(ctx);
        return NULL;
    }
    /* 's' should never be NULL */
    if (s->is_revoked) {
        JS_ThrowTypeErrorRevokedProxy(ctx);
        return NULL;
    }
    method = JS_GetProperty(ctx, s->handler, name);
    if (JS_IsException(method))
        return NULL;
    if (JS_IsNull(method))
        method = JS_UNDEFINED;
    *pmethod = method;
    return s;
}

JSValue js_proxy_getPrototypeOf(JSContext *ctx, JSValueConst obj)
{
    JSProxyData *s;
    JSValue method, ret, proto1;
    int res;

    s = get_proxy_method(ctx, &method, obj, JS_ATOM_getPrototypeOf);
    if (!s)
        return JS_EXCEPTION;
    if (JS_IsUndefined(method))
        return JS_GetPrototype(ctx, s->target);
    ret = JS_CallFree(ctx, method, s->handler, 1, (JSValueConst *)&s->target);
    if (JS_IsException(ret))
        return ret;
    if (JS_VALUE_GET_TAG(ret) != JS_TAG_NULL &&
        JS_VALUE_GET_TAG(ret) != JS_TAG_OBJECT) {
        goto fail;
    }
    res = JS_IsExtensible(ctx, s->target);
    if (res < 0) {
        JS_FreeValue(ctx, ret);
        return JS_EXCEPTION;
    }
    if (!res) {
        /* check invariant */
        proto1 = JS_GetPrototype(ctx, s->target);
        if (JS_IsException(proto1)) {
            JS_FreeValue(ctx, ret);
            return JS_EXCEPTION;
        }
        if (JS_VALUE_GET_OBJ(proto1) != JS_VALUE_GET_OBJ(ret)) {
            JS_FreeValue(ctx, proto1);
        fail:
            JS_FreeValue(ctx, ret);
            return JS_ThrowTypeError(ctx, "proxy: inconsistent prototype");
        }
        JS_FreeValue(ctx, proto1);
    }
    return ret;
}

int js_proxy_setPrototypeOf(JSContext *ctx, JSValueConst obj,
                            JSValueConst proto_val, BOOL throw_flag)
{
    JSProxyData *s;
    JSValue method, ret, proto1;
    JSValueConst args[2];
    BOOL res;
    int res2;

    s = get_proxy_method(ctx, &method, obj, JS_ATOM_setPrototypeOf);
    if (!s)
        return -1;
    if (JS_IsUndefined(method))
        return JS_SetPrototypeInternal(ctx, s->target, proto_val, throw_flag);
    args[0] = s->target;
    args[1] = proto_val;
    ret = JS_CallFree(ctx, method, s->handler, 2, args);
    if (JS_IsException(ret))
        return -1;
    res = JS_ToBoolFree(ctx, ret);
    if (!res) {
        if (throw_flag) {
            JS_ThrowTypeError(ctx, "proxy: bad prototype");
            return -1;
        } else {
            return FALSE;
        }
    }
    res2 = JS_IsExtensible(ctx, s->target);
    if (res2 < 0)
        return -1;
    if (!res2) {
        proto1 = JS_GetPrototype(ctx, s->target);
        if (JS_IsException(proto1))
            return -1;
        if (JS_VALUE_GET_OBJ(proto_val) != JS_VALUE_GET_OBJ(proto1)) {
            JS_FreeValue(ctx, proto1);
            JS_ThrowTypeError(ctx, "proxy: inconsistent prototype");
            return -1;
        }
        JS_FreeValue(ctx, proto1);
    }
    return TRUE;
}

int js_proxy_isExtensible(JSContext *ctx, JSValueConst obj)
{
    JSProxyData *s;
    JSValue method, ret;
    BOOL res;
    int res2;
    s = get_proxy_method(ctx, &method, obj, JS_ATOM_isExtensible);
    if (!s)
        return -1;
    if (JS_IsUndefined(method))
        return JS_IsExtensible(ctx, s->target);
    ret = JS_CallFree(ctx, method, s->handler, 1, (JSValueConst *)&s->target);
    if (JS_IsException(ret))
        return -1;
    res = JS_ToBoolFree(ctx, ret);
    res2 = JS_IsExtensible(ctx, s->target);
    if (res2 < 0)
        return res2;
    if (res != res2) {
        JS_ThrowTypeError(ctx, "proxy: inconsistent isExtensible");
        return -1;
    }
    return res;
}

int js_proxy_preventExtensions(JSContext *ctx, JSValueConst obj)
{
    JSProxyData *s;
    JSValue method, ret;
    BOOL res;
    int res2;
    s = get_proxy_method(ctx, &method, obj, JS_ATOM_preventExtensions);
    if (!s)
        return -1;
    if (JS_IsUndefined(method))
        return JS_PreventExtensions(ctx, s->target);
    ret = JS_CallFree(ctx, method, s->handler, 1, (JSValueConst *)&s->target);
    if (JS_IsException(ret))
        return -1;
    res = JS_ToBoolFree(ctx, ret);
    if (res) {
        res2 = JS_IsExtensible(ctx, s->target);
        if (res2 < 0)
            return res2;
        if (res2) {
            JS_ThrowTypeError(ctx, "proxy: inconsistent preventExtensions");
            return -1;
        }
    }
    return res;
}

static int js_proxy_has(JSContext *ctx, JSValueConst obj, JSAtom atom)
{
    JSProxyData *s;
    JSValue method, ret1, atom_val;
    int ret, res;
    JSObject *p;
    JSValueConst args[2];
    BOOL res2;
    s = get_proxy_method(ctx, &method, obj, JS_ATOM_has);
    if (!s)
        return -1;
    if (JS_IsUndefined(method))
        return JS_HasProperty(ctx, s->target, atom);
    atom_val = JS_AtomToValue(ctx, atom);
    if (JS_IsException(atom_val)) {
        JS_FreeValue(ctx, method);
        return -1;
    }
    args[0] = s->target;
    args[1] = atom_val;
    ret1 = JS_CallFree(ctx, method, s->handler, 2, args);
    JS_FreeValue(ctx, atom_val);
    if (JS_IsException(ret1))
        return -1;
    ret = JS_ToBoolFree(ctx, ret1);
    if (!ret) {
        JSPropertyDescriptor desc;
        p = JS_VALUE_GET_OBJ(s->target);
        res = JS_GetOwnPropertyInternal(ctx, &desc, p, atom);
        if (res < 0)
            return -1;
        if (res) {
            res2 = !(desc.flags & JS_PROP_CONFIGURABLE);
            js_free_desc(ctx, &desc);
            if (res2 || !p->extensible) {
                JS_ThrowTypeError(ctx, "proxy: inconsistent has");
                return -1;
            }
        }
    }
    return ret;
}

static JSValue js_proxy_get(JSContext *ctx, JSValueConst obj, JSAtom atom,
                            JSValueConst receiver)
{
    JSProxyData *s;
    JSValue method, ret, atom_val;
    int res;
    JSValueConst args[3];
    JSPropertyDescriptor desc;
    s = get_proxy_method(ctx, &method, obj, JS_ATOM_get);
    if (!s)
        return JS_EXCEPTION;
    /* Note: recursion is possible thru the prototype of s->target */
    if (JS_IsUndefined(method))
        return JS_GetPropertyInternal(ctx, s->target, atom, receiver, FALSE);
    atom_val = JS_AtomToValue(ctx, atom);
    if (JS_IsException(atom_val)) {
        JS_FreeValue(ctx, method);
        return JS_EXCEPTION;
    }
    args[0] = s->target;
    args[1] = atom_val;
    args[2] = receiver;
    ret = JS_CallFree(ctx, method, s->handler, 3, args);
    JS_FreeValue(ctx, atom_val);
    if (JS_IsException(ret))
        return JS_EXCEPTION;
    res = JS_GetOwnPropertyInternal(ctx, &desc, JS_VALUE_GET_OBJ(s->target), atom);
    if (res < 0)
        return JS_EXCEPTION;
    if (res) {
        if ((desc.flags & (JS_PROP_GETSET | JS_PROP_CONFIGURABLE | JS_PROP_WRITABLE)) == 0) {
            if (!js_same_value(ctx, desc.value, ret)) {
                goto fail;
            }
        } else if ((desc.flags & (JS_PROP_GETSET | JS_PROP_CONFIGURABLE)) == JS_PROP_GETSET) {
            if (JS_IsUndefined(desc.getter) && !JS_IsUndefined(ret)) {
            fail:
                js_free_desc(ctx, &desc);
                JS_FreeValue(ctx, ret);
                return JS_ThrowTypeError(ctx, "proxy: inconsistent get");
            }
        }
        js_free_desc(ctx, &desc);
    }
    return ret;
}

static int js_proxy_set(JSContext *ctx, JSValueConst obj, JSAtom atom,
                        JSValueConst value, JSValueConst receiver, int flags)
{
    JSProxyData *s;
    JSValue method, ret1, atom_val;
    int ret, res;
    JSValueConst args[4];
    s = get_proxy_method(ctx, &method, obj, JS_ATOM_set);
    if (!s)
        return -1;
    if (JS_IsUndefined(method)) {
        return JS_SetPropertyGeneric(ctx, s->target, atom,
                                     JS_DupValue(ctx, value), receiver,
                                     flags);
    }
    atom_val = JS_AtomToValue(ctx, atom);
    if (JS_IsException(atom_val)) {
        JS_FreeValue(ctx, method);
        return -1;
    }
    args[0] = s->target;
    args[1] = atom_val;
    args[2] = value;
    args[3] = receiver;
    ret1 = JS_CallFree(ctx, method, s->handler, 4, args);
    JS_FreeValue(ctx, atom_val);
    if (JS_IsException(ret1))
        return -1;
    ret = JS_ToBoolFree(ctx, ret1);
    if (ret) {
        JSPropertyDescriptor desc;
        res = JS_GetOwnPropertyInternal(ctx, &desc, JS_VALUE_GET_OBJ(s->target), atom);
        if (res < 0)
            return -1;
        if (res) {
            if ((desc.flags & (JS_PROP_GETSET | JS_PROP_CONFIGURABLE | JS_PROP_WRITABLE)) == 0) {
                if (!js_same_value(ctx, desc.value, value)) {
                    goto fail;
                }
            } else if ((desc.flags & (JS_PROP_GETSET | JS_PROP_CONFIGURABLE)) == JS_PROP_GETSET && JS_IsUndefined(desc.setter)) {
                fail:
                    js_free_desc(ctx, &desc);
                    JS_ThrowTypeError(ctx, "proxy: inconsistent set");
                    return -1;
            }
            js_free_desc(ctx, &desc);
        }
    } else {
        if ((flags & JS_PROP_THROW) ||
            ((flags & JS_PROP_THROW_STRICT) && is_strict_mode(ctx))) {
            JS_ThrowTypeError(ctx, "proxy: cannot set property");
            return -1;
        }
    }
    return ret;
}

static JSValue js_create_desc(JSContext *ctx, JSValueConst val,
                              JSValueConst getter, JSValueConst setter,
                              int flags)
{
    JSValue ret;
    ret = JS_NewObject(ctx);
    if (JS_IsException(ret))
        return ret;
    if (flags & JS_PROP_HAS_GET) {
        JS_DefinePropertyValue(ctx, ret, JS_ATOM_get, JS_DupValue(ctx, getter),
                               JS_PROP_C_W_E);
    }
    if (flags & JS_PROP_HAS_SET) {
        JS_DefinePropertyValue(ctx, ret, JS_ATOM_set, JS_DupValue(ctx, setter),
                               JS_PROP_C_W_E);
    }
    if (flags & JS_PROP_HAS_VALUE) {
        JS_DefinePropertyValue(ctx, ret, JS_ATOM_value, JS_DupValue(ctx, val),
                               JS_PROP_C_W_E);
    }
    if (flags & JS_PROP_HAS_WRITABLE) {
        JS_DefinePropertyValue(ctx, ret, JS_ATOM_writable,
                               JS_NewBool(ctx, (flags & JS_PROP_WRITABLE) != 0),
                               JS_PROP_C_W_E);
    }
    if (flags & JS_PROP_HAS_ENUMERABLE) {
        JS_DefinePropertyValue(ctx, ret, JS_ATOM_enumerable,
                               JS_NewBool(ctx, (flags & JS_PROP_ENUMERABLE) != 0),
                               JS_PROP_C_W_E);
    }
    if (flags & JS_PROP_HAS_CONFIGURABLE) {
        JS_DefinePropertyValue(ctx, ret, JS_ATOM_configurable,
                               JS_NewBool(ctx, (flags & JS_PROP_CONFIGURABLE) != 0),
                               JS_PROP_C_W_E);
    }
    return ret;
}

static int js_proxy_get_own_property(JSContext *ctx, JSPropertyDescriptor *pdesc,
                                     JSValueConst obj, JSAtom prop)
{
    JSProxyData *s;
    JSValue method, trap_result_obj, prop_val;
    int res, target_desc_ret, ret;
    JSObject *p;
    JSValueConst args[2];
    JSPropertyDescriptor result_desc, target_desc;
    s = get_proxy_method(ctx, &method, obj, JS_ATOM_getOwnPropertyDescriptor);
    if (!s)
        return -1;
    p = JS_VALUE_GET_OBJ(s->target);
    if (JS_IsUndefined(method)) {
        return JS_GetOwnPropertyInternal(ctx, pdesc, p, prop);
    }
    prop_val = JS_AtomToValue(ctx, prop);
    if (JS_IsException(prop_val)) {
        JS_FreeValue(ctx, method);
        return -1;
    }
    args[0] = s->target;
    args[1] = prop_val;
    trap_result_obj = JS_CallFree(ctx, method, s->handler, 2, args);
    JS_FreeValue(ctx, prop_val);
    if (JS_IsException(trap_result_obj))
        return -1;
    if (!JS_IsObject(trap_result_obj) && !JS_IsUndefined(trap_result_obj)) {
        JS_FreeValue(ctx, trap_result_obj);
        goto fail;
    }
    target_desc_ret = JS_GetOwnPropertyInternal(ctx, &target_desc, p, prop);
    if (target_desc_ret < 0) {
        JS_FreeValue(ctx, trap_result_obj);
        return -1;
    }
    if (target_desc_ret)
        js_free_desc(ctx, &target_desc);
    if (JS_IsUndefined(trap_result_obj)) {
        if (target_desc_ret) {
            if (!(target_desc.flags & JS_PROP_CONFIGURABLE) || !p->extensible)
                goto fail;
        }
        ret = FALSE;
    } else {
        int flags1, extensible_target;
        extensible_target = JS_IsExtensible(ctx, s->target);
        if (extensible_target < 0) {
            JS_FreeValue(ctx, trap_result_obj);
            return -1;
        }
        res = js_obj_to_desc(ctx, &result_desc, trap_result_obj);
        JS_FreeValue(ctx, trap_result_obj);
        if (res < 0)
            return -1;
        if (target_desc_ret) {
            /* convert result_desc.flags to defineProperty flags */
            flags1 = result_desc.flags | JS_PROP_HAS_CONFIGURABLE | JS_PROP_HAS_ENUMERABLE;
            if (result_desc.flags & JS_PROP_GETSET)
                flags1 |= JS_PROP_HAS_GET | JS_PROP_HAS_SET;
            else
                flags1 |= JS_PROP_HAS_VALUE | JS_PROP_HAS_WRITABLE;
            /* XXX: not complete check: need to compare value &
               getter/setter as in defineproperty */
            if (!check_define_prop_flags(target_desc.flags, flags1))
                goto fail1;
        } else {
            if (!extensible_target)
                goto fail1;
        }
        if (!(result_desc.flags & JS_PROP_CONFIGURABLE)) {
            if (!target_desc_ret || (target_desc.flags & JS_PROP_CONFIGURABLE))
                goto fail1;
            if ((result_desc.flags &
                 (JS_PROP_GETSET | JS_PROP_WRITABLE)) == 0 &&
                target_desc_ret &&
                (target_desc.flags & JS_PROP_WRITABLE) != 0) {
                /* proxy-missing-checks */
            fail1:
                js_free_desc(ctx, &result_desc);
            fail:
                JS_ThrowTypeError(ctx, "proxy: inconsistent getOwnPropertyDescriptor");
                return -1;
            }
        }
        ret = TRUE;
        if (pdesc) {
            *pdesc = result_desc;
        } else {
            js_free_desc(ctx, &result_desc);
        }
    }
    return ret;
}

static int js_proxy_define_own_property(JSContext *ctx, JSValueConst obj,
                                        JSAtom prop, JSValueConst val,
                                        JSValueConst getter, JSValueConst setter,
                                        int flags)
{
    JSProxyData *s;
    JSValue method, ret1, prop_val, desc_val;
    int res, ret;
    JSObject *p;
    JSValueConst args[3];
    JSPropertyDescriptor desc;
    BOOL setting_not_configurable;
    s = get_proxy_method(ctx, &method, obj, JS_ATOM_defineProperty);
    if (!s)
        return -1;
    if (JS_IsUndefined(method)) {
        return JS_DefineProperty(ctx, s->target, prop, val, getter, setter, flags);
    }
    prop_val = JS_AtomToValue(ctx, prop);
    if (JS_IsException(prop_val)) {
        JS_FreeValue(ctx, method);
        return -1;
    }
    desc_val = js_create_desc(ctx, val, getter, setter, flags);
    if (JS_IsException(desc_val)) {
        JS_FreeValue(ctx, prop_val);
        JS_FreeValue(ctx, method);
        return -1;
    }
    args[0] = s->target;
    args[1] = prop_val;
    args[2] = desc_val;
    ret1 = JS_CallFree(ctx, method, s->handler, 3, args);
    JS_FreeValue(ctx, prop_val);
    JS_FreeValue(ctx, desc_val);
    if (JS_IsException(ret1))
        return -1;
    ret = JS_ToBoolFree(ctx, ret1);
    if (!ret) {
        if (flags & JS_PROP_THROW) {
            JS_ThrowTypeError(ctx, "proxy: defineProperty exception");
            return -1;
        } else {
            return 0;
        }
    }
    p = JS_VALUE_GET_OBJ(s->target);
    res = JS_GetOwnPropertyInternal(ctx, &desc, p, prop);
    if (res < 0)
        return -1;
    setting_not_configurable = ((flags & (JS_PROP_HAS_CONFIGURABLE |
                                          JS_PROP_CONFIGURABLE)) ==
                                JS_PROP_HAS_CONFIGURABLE);
    if (!res) {
        if (!p->extensible || setting_not_configurable)
            goto fail;
    } else {
        if (!check_define_prop_flags(desc.flags, flags) ||
            ((desc.flags & JS_PROP_CONFIGURABLE) && setting_not_configurable)) {
            goto fail1;
        }
        if (flags & (JS_PROP_HAS_GET | JS_PROP_HAS_SET)) {
            if ((desc.flags & (JS_PROP_GETSET | JS_PROP_CONFIGURABLE)) ==
                JS_PROP_GETSET) {
                if ((flags & JS_PROP_HAS_GET) &&
                    !js_same_value(ctx, getter, desc.getter)) {
                    goto fail1;
                }
                if ((flags & JS_PROP_HAS_SET) &&
                    !js_same_value(ctx, setter, desc.setter)) {
                    goto fail1;
                }
            }
        } else if (flags & JS_PROP_HAS_VALUE) {
            if ((desc.flags & (JS_PROP_CONFIGURABLE | JS_PROP_WRITABLE)) ==
                JS_PROP_WRITABLE && !(flags & JS_PROP_WRITABLE)) {
                /* missing-proxy-check feature */
                goto fail1;
            } else if ((desc.flags & (JS_PROP_CONFIGURABLE | JS_PROP_WRITABLE)) == 0 &&
                !js_same_value(ctx, val, desc.value)) {
                goto fail1;
            }
        }
        if (flags & JS_PROP_HAS_WRITABLE) {
            if ((desc.flags & (JS_PROP_GETSET | JS_PROP_CONFIGURABLE |
                               JS_PROP_WRITABLE)) == JS_PROP_WRITABLE) {
                /* proxy-missing-checks */
            fail1:
                js_free_desc(ctx, &desc);
            fail:
                JS_ThrowTypeError(ctx, "proxy: inconsistent defineProperty");
                return -1;
            }
        }
        js_free_desc(ctx, &desc);
    }
    return 1;
}

static int js_proxy_delete_property(JSContext *ctx, JSValueConst obj,
                                    JSAtom atom)
{
    JSProxyData *s;
    JSValue method, ret, atom_val;
    int res, res2, is_extensible;
    JSValueConst args[2];

    s = get_proxy_method(ctx, &method, obj, JS_ATOM_deleteProperty);
    if (!s)
        return -1;
    if (JS_IsUndefined(method)) {
        return JS_DeleteProperty(ctx, s->target, atom, 0);
    }
    atom_val = JS_AtomToValue(ctx, atom);;
    if (JS_IsException(atom_val)) {
        JS_FreeValue(ctx, method);
        return -1;
    }
    args[0] = s->target;
    args[1] = atom_val;
    ret = JS_CallFree(ctx, method, s->handler, 2, args);
    JS_FreeValue(ctx, atom_val);
    if (JS_IsException(ret))
        return -1;
    res = JS_ToBoolFree(ctx, ret);
    if (res) {
        JSPropertyDescriptor desc;
        res2 = JS_GetOwnPropertyInternal(ctx, &desc, JS_VALUE_GET_OBJ(s->target), atom);
        if (res2 < 0)
            return -1;
        if (res2) {
            if (!(desc.flags & JS_PROP_CONFIGURABLE))
                goto fail;
            is_extensible = JS_IsExtensible(ctx, s->target);
            if (is_extensible < 0)
                goto fail1;
            if (!is_extensible) {
                /* proxy-missing-checks */
            fail:
                JS_ThrowTypeError(ctx, "proxy: inconsistent deleteProperty");
            fail1:
                js_free_desc(ctx, &desc);
                return -1;
            }
            js_free_desc(ctx, &desc);
        }
    }
    return res;
}

/* return the index of the property or -1 if not found */
static int find_prop_key(const JSPropertyEnum *tab, int n, JSAtom atom)
{
    int i;
    for(i = 0; i < n; i++) {
        if (tab[i].atom == atom)
            return i;
    }
    return -1;
}

static int js_proxy_get_own_property_names(JSContext *ctx,
                                           JSPropertyEnum **ptab,
                                           uint32_t *plen,
                                           JSValueConst obj)
{
    JSProxyData *s;
    JSValue method, prop_array, val;
    uint32_t len, i, len2;
    JSPropertyEnum *tab, *tab2;
    JSAtom atom;
    JSPropertyDescriptor desc;
    int res, is_extensible, idx;
    s = get_proxy_method(ctx, &method, obj, JS_ATOM_ownKeys);
    if (!s)
        return -1;
    if (JS_IsUndefined(method)) {
        return JS_GetOwnPropertyNamesInternal(ctx, ptab, plen,
                                      JS_VALUE_GET_OBJ(s->target),
                                      JS_GPN_STRING_MASK | JS_GPN_SYMBOL_MASK);
    }
    prop_array = JS_CallFree(ctx, method, s->handler, 1, (JSValueConst *)&s->target);
    if (JS_IsException(prop_array))
        return -1;
    tab = NULL;
    len = 0;
    tab2 = NULL;
    len2 = 0;
    if (js_get_length32(ctx, &len, prop_array))
        goto fail;
    if (len > 0) {
        tab = js_mallocz(ctx, sizeof(tab[0]) * len);
        if (!tab)
            goto fail;
    }
    for(i = 0; i < len; i++) {
        val = JS_GetPropertyUint32(ctx, prop_array, i);
        if (JS_IsException(val))
            goto fail;
        if (!JS_IsString(val) && !JS_IsSymbol(val)) {
            JS_FreeValue(ctx, val);
            JS_ThrowTypeError(ctx, "proxy: properties must be strings or symbols");
            goto fail;
        }
        atom = JS_ValueToAtom(ctx, val);
        JS_FreeValue(ctx, val);
        if (atom == JS_ATOM_NULL)
            goto fail;
        tab[i].atom = atom;
        tab[i].is_enumerable = FALSE; /* XXX: redundant? */
    }
    /* check duplicate properties (XXX: inefficient, could store the
     * properties an a temporary object to use the hash) */
    for(i = 1; i < len; i++) {
        if (find_prop_key(tab, i, tab[i].atom) >= 0) {
            JS_ThrowTypeError(ctx, "proxy: duplicate property");
            goto fail;
        }
    }
    is_extensible = JS_IsExtensible(ctx, s->target);
    if (is_extensible < 0)
        goto fail;
    /* check if there are non configurable properties */
    if (s->is_revoked) {
        JS_ThrowTypeErrorRevokedProxy(ctx);
        goto fail;
    }
    if (JS_GetOwnPropertyNamesInternal(ctx, &tab2, &len2, JS_VALUE_GET_OBJ(s->target),
                               JS_GPN_STRING_MASK | JS_GPN_SYMBOL_MASK))
        goto fail;
    for(i = 0; i < len2; i++) {
        if (s->is_revoked) {
            JS_ThrowTypeErrorRevokedProxy(ctx);
            goto fail;
        }
        res = JS_GetOwnPropertyInternal(ctx, &desc, JS_VALUE_GET_OBJ(s->target),
                                tab2[i].atom);
        if (res < 0)
            goto fail;
        if (res) {  /* safety, property should be found */
            js_free_desc(ctx, &desc);
            if (!(desc.flags & JS_PROP_CONFIGURABLE) || !is_extensible) {
                idx = find_prop_key(tab, len, tab2[i].atom);
                if (idx < 0) {
                    JS_ThrowTypeError(ctx, "proxy: target property must be present in proxy ownKeys");
                    goto fail;
                }
                /* mark the property as found */
                if (!is_extensible)
                    tab[idx].is_enumerable = TRUE;
            }
        }
    }
    if (!is_extensible) {
        /* check that all property in 'tab' were checked */
        for(i = 0; i < len; i++) {
            if (!tab[i].is_enumerable) {
                JS_ThrowTypeError(ctx, "proxy: property not present in target were returned by non extensible proxy");
                goto fail;
            }
        }
    }
    js_free_prop_enum(ctx, tab2, len2);
    JS_FreeValue(ctx, prop_array);
    *ptab = tab;
    *plen = len;
    return 0;
 fail:
    js_free_prop_enum(ctx, tab2, len2);
    js_free_prop_enum(ctx, tab, len);
    JS_FreeValue(ctx, prop_array);
    return -1;
}

static JSValue js_proxy_call_constructor(JSContext *ctx, JSValueConst func_obj,
                                         JSValueConst new_target,
                                         int argc, JSValueConst *argv)
{
    JSProxyData *s;
    JSValue method, arg_array, ret;
    JSValueConst args[3];

    s = get_proxy_method(ctx, &method, func_obj, JS_ATOM_construct);
    if (!s)
        return JS_EXCEPTION;
    if (!JS_IsConstructor(ctx, s->target))
        return JS_ThrowTypeError(ctx, "not a constructor");
    if (JS_IsUndefined(method))
        return JS_CallConstructor2(ctx, s->target, new_target, argc, argv);
    arg_array = js_create_array(ctx, argc, argv);
    if (JS_IsException(arg_array)) {
        ret = JS_EXCEPTION;
        goto fail;
    }
    args[0] = s->target;
    args[1] = arg_array;
    args[2] = new_target;
    ret = JS_Call(ctx, method, s->handler, 3, args);
    if (!JS_IsException(ret) && JS_VALUE_GET_TAG(ret) != JS_TAG_OBJECT) {
        JS_FreeValue(ctx, ret);
        ret = JS_ThrowTypeErrorNotAnObject(ctx);
    }
 fail:
    JS_FreeValue(ctx, method);
    JS_FreeValue(ctx, arg_array);
    return ret;
}

static JSValue js_proxy_call(JSContext *ctx, JSValueConst func_obj,
                             JSValueConst this_obj,
                             int argc, JSValueConst *argv, int flags)
{
    JSProxyData *s;
    JSValue method, arg_array, ret;
    JSValueConst args[3];

    if (flags & JS_CALL_FLAG_CONSTRUCTOR)
        return js_proxy_call_constructor(ctx, func_obj, this_obj, argc, argv);

    s = get_proxy_method(ctx, &method, func_obj, JS_ATOM_apply);
    if (!s)
        return JS_EXCEPTION;
    if (!s->is_func) {
        JS_FreeValue(ctx, method);
        return JS_ThrowTypeError(ctx, "not a function");
    }
    if (JS_IsUndefined(method))
        return JS_Call(ctx, s->target, this_obj, argc, argv);
    arg_array = js_create_array(ctx, argc, argv);
    if (JS_IsException(arg_array)) {
        ret = JS_EXCEPTION;
        goto fail;
    }
    args[0] = s->target;
    args[1] = this_obj;
    args[2] = arg_array;
    ret = JS_Call(ctx, method, s->handler, 3, args);
 fail:
    JS_FreeValue(ctx, method);
    JS_FreeValue(ctx, arg_array);
    return ret;
}

int js_proxy_isArray(JSContext *ctx, JSValueConst obj)
{
    JSProxyData *s = JS_GetOpaque(obj, JS_CLASS_PROXY);
    if (!s)
        return FALSE;
    if (s->is_revoked) {
        JS_ThrowTypeErrorRevokedProxy(ctx);
        return -1;
    }
    return JS_IsArray(ctx, s->target);
}

static const JSClassExoticMethods js_proxy_exotic_methods = {
    .get_own_property = js_proxy_get_own_property,
    .define_own_property = js_proxy_define_own_property,
    .delete_property = js_proxy_delete_property,
    .get_own_property_names = js_proxy_get_own_property_names,
    .has_property = js_proxy_has,
    .get_property = js_proxy_get,
    .set_property = js_proxy_set,
};

static JSValue js_proxy_constructor(JSContext *ctx, JSValueConst this_val,
                                    int argc, JSValueConst *argv)
{
    JSValueConst target, handler;
    JSValue obj;
    JSProxyData *s;

    target = argv[0];
    handler = argv[1];
    if (JS_VALUE_GET_TAG(target) != JS_TAG_OBJECT ||
        JS_VALUE_GET_TAG(handler) != JS_TAG_OBJECT)
        return JS_ThrowTypeErrorNotAnObject(ctx);

    obj = JS_NewObjectProtoClass(ctx, JS_NULL, JS_CLASS_PROXY);
    if (JS_IsException(obj))
        return obj;
    s = js_malloc(ctx, sizeof(JSProxyData));
    if (!s) {
        JS_FreeValue(ctx, obj);
        return JS_EXCEPTION;
    }
    s->target = JS_DupValue(ctx, target);
    s->handler = JS_DupValue(ctx, handler);
    s->is_func = JS_IsFunction(ctx, target);
    s->is_revoked = FALSE;
    JS_SetOpaque(obj, s);
    JS_SetConstructorBit(ctx, obj, JS_IsConstructor(ctx, target));
    return obj;
}

static JSValue js_proxy_revoke(JSContext *ctx, JSValueConst this_val,
                               int argc, JSValueConst *argv, int magic,
                               JSValue *func_data)
{
    JSProxyData *s = JS_GetOpaque(func_data[0], JS_CLASS_PROXY);
    if (s) {
        /* We do not free the handler and target in case they are
           referenced as constants in the C call stack */
        s->is_revoked = TRUE;
        JS_FreeValue(ctx, func_data[0]);
        func_data[0] = JS_NULL;
    }
    return JS_UNDEFINED;
}

static JSValue js_proxy_revoke_constructor(JSContext *ctx,
                                           JSValueConst proxy_obj)
{
    return JS_NewCFunctionData(ctx, js_proxy_revoke, 0, 0, 1, &proxy_obj);
}

static JSValue js_proxy_revocable(JSContext *ctx, JSValueConst this_val,
                                 int argc, JSValueConst *argv)
{
    JSValue proxy_obj, revoke_obj = JS_UNDEFINED, obj;
    proxy_obj = js_proxy_constructor(ctx, JS_UNDEFINED, argc, argv);
    if (JS_IsException(proxy_obj))
        goto fail;
    revoke_obj = js_proxy_revoke_constructor(ctx, proxy_obj);
    if (JS_IsException(revoke_obj))
        goto fail;
    obj = JS_NewObject(ctx);
    if (JS_IsException(obj))
        goto fail;
    // XXX: exceptions?
    JS_DefinePropertyValue(ctx, obj, JS_ATOM_proxy, proxy_obj, JS_PROP_C_W_E);
    JS_DefinePropertyValue(ctx, obj, JS_ATOM_revoke, revoke_obj, JS_PROP_C_W_E);
    return obj;
 fail:
    JS_FreeValue(ctx, proxy_obj);
    JS_FreeValue(ctx, revoke_obj);
    return JS_EXCEPTION;
}

static const JSCFunctionListEntry js_proxy_funcs[] = {
    JS_CFUNC_DEF("revocable", 2, js_proxy_revocable ),
};

static const JSClassShortDef js_proxy_class_def[] = {
    { JS_ATOM_Object, js_proxy_finalizer, js_proxy_mark }, /* JS_CLASS_PROXY */
};

void JS_AddIntrinsicProxy(JSContext *ctx)
{
    JSRuntime *rt = ctx->rt;
    JSValue obj1;
    if (!JS_IsRegisteredClass(rt, JS_CLASS_PROXY)) {
        init_class_range(rt, js_proxy_class_def, JS_CLASS_PROXY,
                         countof(js_proxy_class_def));
        rt->class_array[JS_CLASS_PROXY].exotic = &js_proxy_exotic_methods;
        rt->class_array[JS_CLASS_PROXY].call = js_proxy_call;
    }
    obj1 = JS_NewCFunction2(ctx, js_proxy_constructor, "Proxy", 2,
                            JS_CFUNC_constructor, 0);
    JS_SetConstructorBit(ctx, obj1, TRUE);
    JS_SetPropertyFunctionList(ctx, obj1, js_proxy_funcs,
                               countof(js_proxy_funcs));
    JS_DefinePropertyValueStr(ctx, ctx->global_obj, "Proxy",
                              obj1, JS_PROP_WRITABLE | JS_PROP_CONFIGURABLE);
}