jsobj.c

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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*
 * JS object implementation.
 */
#include "jsstddef.h"
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsarena.h" /* Added by JSIFY */
#include "jsutil.h" /* Added by JSIFY */
#include "jshash.h" /* Added by JSIFY */
#include "jsdhash.h"
#include "jsprf.h"
#include "jsapi.h"
#include "jsarray.h"
#include "jsatom.h"
#include "jsbool.h"
#include "jscntxt.h"
#include "jsconfig.h"
#include "jsfun.h"
#include "jsgc.h"
#include "jsinterp.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsscope.h"
#include "jsscript.h"
#include "jsstr.h"
#include "jsopcode.h"

#include "jsdbgapi.h"   /* whether or not JS_HAS_OBJ_WATCHPOINT */

#ifdef JS_THREADSAFE
#define NATIVE_DROP_PROPERTY js_DropProperty

extern void
js_DropProperty(JSContext *cx, JSObject *obj, JSProperty *prop);
#else
#define NATIVE_DROP_PROPERTY NULL
#endif

#ifdef XP_MAC
#pragma export on
#endif

JS_FRIEND_DATA(JSObjectOps) js_ObjectOps = {
    js_NewObjectMap,        js_DestroyObjectMap,
#if defined JS_THREADSAFE && defined DEBUG
    _js_LookupProperty,     js_DefineProperty,
#else
    js_LookupProperty,      js_DefineProperty,
#endif
    js_GetProperty,         js_SetProperty,
    js_GetAttributes,       js_SetAttributes,
    js_DeleteProperty,      js_DefaultValue,
    js_Enumerate,           js_CheckAccess,
    NULL,                   NATIVE_DROP_PROPERTY,
    js_Call,                js_Construct,
    NULL,                   js_HasInstance,
    js_SetProtoOrParent,    js_SetProtoOrParent,
    js_Mark,                js_Clear,
    js_GetRequiredSlot,     js_SetRequiredSlot
};

#ifdef XP_MAC
#pragma export off
#endif

JSClass js_ObjectClass = {
    js_Object_str,
    0,
    JS_PropertyStub,  JS_PropertyStub,  JS_PropertyStub,  JS_PropertyStub,
    JS_EnumerateStub, JS_ResolveStub,   JS_ConvertStub,   JS_FinalizeStub,
    JSCLASS_NO_OPTIONAL_MEMBERS
};

#if JS_HAS_OBJ_PROTO_PROP

static JSBool
obj_getSlot(JSContext *cx, JSObject *obj, jsval id, jsval *vp);

static JSBool
obj_setSlot(JSContext *cx, JSObject *obj, jsval id, jsval *vp);

static JSBool
obj_getCount(JSContext *cx, JSObject *obj, jsval id, jsval *vp);

static JSPropertySpec object_props[] = {
    /* These two must come first; see object_props[slot].name usage below. */
    {js_proto_str, JSSLOT_PROTO, JSPROP_PERMANENT|JSPROP_SHARED,
                                                  obj_getSlot,  obj_setSlot},
    {js_parent_str,JSSLOT_PARENT,JSPROP_READONLY|JSPROP_PERMANENT|JSPROP_SHARED,
                                                  obj_getSlot,  obj_setSlot},
    {js_count_str, 0,            JSPROP_PERMANENT,obj_getCount, obj_getCount},
    {0,0,0,0,0}
};

/* NB: JSSLOT_PROTO and JSSLOT_PARENT are already indexes into object_props. */
#define JSSLOT_COUNT 2

static JSBool
ReportStrictSlot(JSContext *cx, uint32 slot)
{
    if (slot == JSSLOT_PROTO)
        return JS_TRUE;
    return JS_ReportErrorFlagsAndNumber(cx,
                                        JSREPORT_WARNING | JSREPORT_STRICT,
                                        js_GetErrorMessage, NULL,
                                        JSMSG_DEPRECATED_USAGE,
                                        object_props[slot].name);
}

static JSBool
obj_getSlot(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    uint32 slot;
    JSAccessMode mode;
    uintN attrs;

    slot = (uint32) JSVAL_TO_INT(id);
    if (JS_HAS_STRICT_OPTION(cx) && !ReportStrictSlot(cx, slot))
        return JS_FALSE;
    if (id == INT_TO_JSVAL(JSSLOT_PROTO)) {
        id = (jsid)cx->runtime->atomState.protoAtom;
        mode = JSACC_PROTO;
    } else {
        id = (jsid)cx->runtime->atomState.parentAtom;
        mode = JSACC_PARENT;
    }
    if (!OBJ_CHECK_ACCESS(cx, obj, id, mode, vp, &attrs))
        return JS_FALSE;
    *vp = OBJ_GET_SLOT(cx, obj, slot);
    return JS_TRUE;
}

static JSBool
obj_setSlot(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    JSObject *pobj;
    uint32 slot;
    uintN attrs;

    if (!JSVAL_IS_OBJECT(*vp))
        return JS_TRUE;
    pobj = JSVAL_TO_OBJECT(*vp);
    slot = (uint32) JSVAL_TO_INT(id);
    if (JS_HAS_STRICT_OPTION(cx) && !ReportStrictSlot(cx, slot))
        return JS_FALSE;

    /* __parent__ is readonly and permanent, only __proto__ may be set. */
    if (!OBJ_CHECK_ACCESS(cx, obj, id, JSACC_PROTO | JSACC_WRITE, vp, &attrs))
        return JS_FALSE;

    return js_SetProtoOrParent(cx, obj, slot, pobj);
}

static JSBool
obj_getCount(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    jsval iter_state;
    jsid num_properties;
    JSBool ok;

    if (JS_HAS_STRICT_OPTION(cx) && !ReportStrictSlot(cx, JSSLOT_COUNT))
        return JS_FALSE;

    /* Get the number of properties to enumerate. */
    iter_state = JSVAL_NULL;
    ok = OBJ_ENUMERATE(cx, obj, JSENUMERATE_INIT, &iter_state, &num_properties);
    if (!ok)
        goto out;

    if (!JSVAL_IS_INT(num_properties)) {
        JS_ASSERT(0);
        *vp = JSVAL_ZERO;
        goto out;
    }
    *vp = num_properties;

out:
    if (iter_state != JSVAL_NULL)
        ok = OBJ_ENUMERATE(cx, obj, JSENUMERATE_DESTROY, &iter_state, 0);
    return ok;
}

#else  /* !JS_HAS_OBJ_PROTO_PROP */

#define object_props NULL

#endif /* !JS_HAS_OBJ_PROTO_PROP */

JSBool
js_SetProtoOrParent(JSContext *cx, JSObject *obj, uint32 slot, JSObject *pobj)
{
    JSRuntime *rt;
    JSObject *obj2, *oldproto;
    JSScope *scope, *newscope;

    /*
     * Serialize all proto and parent setting in order to detect cycles.
     * We nest locks in this function, and only here, in the following orders:
     *
     * (1)  rt->setSlotLock < pobj's scope lock;
     *      rt->setSlotLock < pobj's proto-or-parent's scope lock;
     *      rt->setSlotLock < pobj's grand-proto-or-parent's scope lock;
     *      etc...
     * (2)  rt->setSlotLock < obj's scope lock < pobj's scope lock.
     *
     * We avoid AB-BA deadlock by restricting obj from being on pobj's parent
     * or proto chain (pobj may already be on obj's parent or proto chain; it
     * could be moving up or down).  We finally order obj with respect to pobj
     * at the bottom of this routine (just before releasing rt->setSlotLock),
     * by making pobj be obj's prototype or parent.
     *
     * After we have set the slot and released rt->setSlotLock, another call
     * to js_SetProtoOrParent could nest locks according to the first order
     * list above, but it cannot deadlock with any other thread.  For there
     * to be a deadlock, other parts of the engine would have to nest scope
     * locks in the opposite order.  XXXbe ensure they don't!
     */
    rt = cx->runtime;
#ifdef JS_THREADSAFE

    JS_ACQUIRE_LOCK(rt->setSlotLock);
    while (rt->setSlotBusy) {
        jsrefcount saveDepth;

        /* Take pains to avoid nesting rt->gcLock inside rt->setSlotLock! */
        JS_RELEASE_LOCK(rt->setSlotLock);
        saveDepth = JS_SuspendRequest(cx);
        JS_ACQUIRE_LOCK(rt->setSlotLock);
        if (rt->setSlotBusy)
            JS_WAIT_CONDVAR(rt->setSlotDone, JS_NO_TIMEOUT);
        JS_RELEASE_LOCK(rt->setSlotLock);
        JS_ResumeRequest(cx, saveDepth);
        JS_ACQUIRE_LOCK(rt->setSlotLock);
    }
    rt->setSlotBusy = JS_TRUE;
    JS_RELEASE_LOCK(rt->setSlotLock);

#define SET_SLOT_DONE(rt)                                                     \
    JS_BEGIN_MACRO                                                            \
        JS_ACQUIRE_LOCK((rt)->setSlotLock);                                   \
        (rt)->setSlotBusy = JS_FALSE;                                         \
        JS_NOTIFY_ALL_CONDVAR((rt)->setSlotDone);                             \
        JS_RELEASE_LOCK((rt)->setSlotLock);                                   \
    JS_END_MACRO

#else

#define SET_SLOT_DONE(rt)       /* nothing */

#endif

    obj2 = pobj;
    while (obj2) {
        if (obj2 == obj) {
            SET_SLOT_DONE(rt);
            JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                                 JSMSG_CYCLIC_VALUE,
#if JS_HAS_OBJ_PROTO_PROP
                                 object_props[slot].name
#else
                                 (slot == JSSLOT_PROTO) ? js_proto_str
                                                        : js_parent_str
#endif
                                 );
            return JS_FALSE;
        }
        obj2 = JSVAL_TO_OBJECT(OBJ_GET_SLOT(cx, obj2, slot));
    }

    if (slot == JSSLOT_PROTO && OBJ_IS_NATIVE(obj)) {
        /* Check to see whether obj shares its prototype's scope. */
        JS_LOCK_OBJ(cx, obj);
        scope = OBJ_SCOPE(obj);
        oldproto = JSVAL_TO_OBJECT(LOCKED_OBJ_GET_SLOT(obj, JSSLOT_PROTO));
        if (oldproto && OBJ_SCOPE(oldproto) == scope) {
            /* Either obj needs a new empty scope, or it should share pobj's. */
            if (!pobj ||
                !OBJ_IS_NATIVE(pobj) ||
                OBJ_GET_CLASS(cx, pobj) != LOCKED_OBJ_GET_CLASS(oldproto)) {
                /*
                 * With no proto and no scope of its own, obj is truly empty.
                 *
                 * If pobj is not native, obj needs its own empty scope -- it
                 * should not continue to share oldproto's scope once oldproto
                 * is not on obj's prototype chain.  That would put properties
                 * from oldproto's scope ahead of properties defined by pobj,
                 * in lookup order.
                 *
                 * If pobj's class differs from oldproto's, we may need a new
                 * scope to handle differences in private and reserved slots,
                 * so we suboptimally but safely make one.
                 */
                scope = js_GetMutableScope(cx, obj);
                if (!scope) {
                    JS_UNLOCK_OBJ(cx, obj);
                    SET_SLOT_DONE(rt);
                    return JS_FALSE;
                }
            } else if (OBJ_SCOPE(pobj) != scope) {
#ifdef JS_THREADSAFE
                /*
                 * We are about to nest scope locks.  Help jslock.c:ShareScope
                 * keep scope->u.count balanced for the JS_UNLOCK_SCOPE, while
                 * avoiding deadlock, by recording scope in rt->setSlotScope.
                 */
                if (scope->ownercx) {
                    JS_ASSERT(scope->ownercx == cx);
                    rt->setSlotScope = scope;
                }
#endif

                /* We can't deadlock because we checked for cycles above (2). */
                JS_LOCK_OBJ(cx, pobj);
                newscope = (JSScope *) js_HoldObjectMap(cx, pobj->map);
                obj->map = &newscope->map;
                js_DropObjectMap(cx, &scope->map, obj);
                JS_TRANSFER_SCOPE_LOCK(cx, scope, newscope);
                scope = newscope;
#ifdef JS_THREADSAFE
                rt->setSlotScope = NULL;
#endif
            }
        }
        LOCKED_OBJ_SET_SLOT(obj, JSSLOT_PROTO, OBJECT_TO_JSVAL(pobj));
        JS_UNLOCK_SCOPE(cx, scope);
    } else {
        OBJ_SET_SLOT(cx, obj, slot, OBJECT_TO_JSVAL(pobj));
    }

    SET_SLOT_DONE(rt);
    return JS_TRUE;

#undef SET_SLOT_DONE
}

JS_STATIC_DLL_CALLBACK(JSHashNumber)
js_hash_object(const void *key)
{
    return (JSHashNumber)key >> JSVAL_TAGBITS;
}

static JSHashEntry *
MarkSharpObjects(JSContext *cx, JSObject *obj, JSIdArray **idap)
{
    JSSharpObjectMap *map;
    JSHashTable *table;
    JSHashNumber hash;
    JSHashEntry **hep, *he;
    jsatomid sharpid;
    JSIdArray *ida;
    JSBool ok;
    jsint i, length;
    jsid id;
#if JS_HAS_GETTER_SETTER
    JSObject *obj2;
    JSProperty *prop;
    uintN attrs;
#endif
    jsval val;

    map = &cx->sharpObjectMap;
    table = map->table;
    hash = js_hash_object(obj);
    hep = JS_HashTableRawLookup(table, hash, obj);
    he = *hep;
    if (!he) {
        sharpid = 0;
        he = JS_HashTableRawAdd(table, hep, hash, obj, (void *)sharpid);
        if (!he) {
            JS_ReportOutOfMemory(cx);
            return NULL;
        }
        ida = JS_Enumerate(cx, obj);
        if (!ida)
            return NULL;
        ok = JS_TRUE;