jsfun.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
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 * 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 function support.
 */
#include "jsstddef.h"
#include <string.h>
#include "jstypes.h"
#include "jsbit.h"
#include "jsutil.h" /* Added by JSIFY */
#include "jsapi.h"
#include "jsarray.h"
#include "jsatom.h"
#include "jscntxt.h"
#include "jsconfig.h"
#include "jsdbgapi.h"
#include "jsfun.h"
#include "jsgc.h"
#include "jsinterp.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsopcode.h"
#include "jsparse.h"
#include "jsscan.h"
#include "jsscope.h"
#include "jsscript.h"
#include "jsstr.h"
#include "jsexn.h"

/* Generic function/call/arguments tinyids -- also reflected bit numbers. */
enum {
    CALL_ARGUMENTS  = -1,       /* predefined arguments local variable */
    CALL_CALLEE     = -2,       /* reference to active function's object */
    ARGS_LENGTH     = -3,       /* number of actual args, arity if inactive */
    ARGS_CALLEE     = -4,       /* reference from arguments to active funobj */
    FUN_ARITY       = -5,       /* number of formal parameters; desired argc */
    FUN_NAME        = -6,       /* function name, "" if anonymous */
    FUN_CALLER      = -7        /* Function.prototype.caller, backward compat */
};

#if JSFRAME_OVERRIDE_BITS < 8
# error "not enough override bits in JSStackFrame.flags!"
#endif

#define TEST_OVERRIDE_BIT(fp, tinyid) \
    ((fp)->flags & JS_BIT(JSFRAME_OVERRIDE_SHIFT - ((tinyid) + 1)))

#define SET_OVERRIDE_BIT(fp, tinyid) \
    ((fp)->flags |= JS_BIT(JSFRAME_OVERRIDE_SHIFT - ((tinyid) + 1)))

#if JS_HAS_ARGS_OBJECT

JSBool
js_GetArgsValue(JSContext *cx, JSStackFrame *fp, jsval *vp)
{
    JSObject *argsobj;

    if (TEST_OVERRIDE_BIT(fp, CALL_ARGUMENTS)) {
        JS_ASSERT(fp->callobj);
        return OBJ_GET_PROPERTY(cx, fp->callobj,
                                (jsid) cx->runtime->atomState.argumentsAtom,
                                vp);
    }
    argsobj = js_GetArgsObject(cx, fp);
    if (!argsobj)
        return JS_FALSE;
    *vp = OBJECT_TO_JSVAL(argsobj);
    return JS_TRUE;
}

#define MAXARGS(fp)     ((fp)->fun ? JS_MAX((fp)->argc, (fp)->fun->nargs)     \
                                   : (fp)->argc)

static JSBool
MarkArgDeleted(JSContext *cx, JSStackFrame *fp, uintN slot)
{
    JSObject *argsobj;
    jsval bmapval, bmapint;
    size_t nbits, nbytes;
    jsbitmap *bitmap;

    argsobj = fp->argsobj;
    (void) JS_GetReservedSlot(cx, argsobj, 0, &bmapval);
    nbits = MAXARGS(fp);
    JS_ASSERT(slot < nbits);
    if (JSVAL_IS_VOID(bmapval)) {
        if (nbits <= JSVAL_INT_BITS) {
            bmapint = 0;
            bitmap = (jsbitmap *) &bmapint;
        } else {
            nbytes = JS_HOWMANY(nbits, JS_BITS_PER_WORD) * sizeof(jsbitmap);
            bitmap = (jsbitmap *) JS_malloc(cx, nbytes);
            if (!bitmap)
                return JS_FALSE;
            memset(bitmap, 0, nbytes);
            bmapval = PRIVATE_TO_JSVAL(bitmap);
            JS_SetReservedSlot(cx, argsobj, 0, bmapval);
        }
    } else {
        if (nbits <= JSVAL_INT_BITS) {
            bmapint = JSVAL_TO_INT(bmapval);
            bitmap = (jsbitmap *) &bmapint;
        } else {
            bitmap = (jsbitmap *) JSVAL_TO_PRIVATE(bmapval);
        }
    }
    JS_SET_BIT(bitmap, slot);
    if (bitmap == (jsbitmap *) &bmapint) {
        bmapval = INT_TO_JSVAL(bmapint);
        JS_SetReservedSlot(cx, argsobj, 0, bmapval);
    }
    return JS_TRUE;
}

/* NB: Infallible predicate, false does not mean error/exception. */
static JSBool
ArgWasDeleted(JSContext *cx, JSStackFrame *fp, uintN slot)
{
    JSObject *argsobj;
    jsval bmapval, bmapint;
    jsbitmap *bitmap;

    argsobj = fp->argsobj;
    (void) JS_GetReservedSlot(cx, argsobj, 0, &bmapval);
    if (JSVAL_IS_VOID(bmapval))
        return JS_FALSE;
    if (MAXARGS(fp) <= JSVAL_INT_BITS) {
        bmapint = JSVAL_TO_INT(bmapval);
        bitmap = (jsbitmap *) &bmapint;
    } else {
        bitmap = (jsbitmap *) JSVAL_TO_PRIVATE(bmapval);
    }
    return JS_TEST_BIT(bitmap, slot) != 0;
}

JSBool
js_GetArgsProperty(JSContext *cx, JSStackFrame *fp, jsid id,
                   JSObject **objp, jsval *vp)
{
    jsval val;
    JSObject *obj;
    uintN slot;

    if (TEST_OVERRIDE_BIT(fp, CALL_ARGUMENTS)) {
        JS_ASSERT(fp->callobj);
        if (!OBJ_GET_PROPERTY(cx, fp->callobj,
                              (jsid) cx->runtime->atomState.argumentsAtom,
                              &val)) {
            return JS_FALSE;
        }
        if (JSVAL_IS_PRIMITIVE(val)) {
            obj = js_ValueToNonNullObject(cx, val);
            if (!obj)
                return JS_FALSE;
        } else {
            obj = JSVAL_TO_OBJECT(val);
        }
        *objp = obj;
        return OBJ_GET_PROPERTY(cx, obj, id, vp);
    }

    *objp = NULL;
    *vp = JSVAL_VOID;
    if (JSVAL_IS_INT(id)) {
        slot = (uintN) JSVAL_TO_INT(id);
        if (slot < MAXARGS(fp)) {
            if (fp->argsobj && ArgWasDeleted(cx, fp, slot))
                return OBJ_GET_PROPERTY(cx, fp->argsobj, id, vp);
            *vp = fp->argv[slot];
        }
    } else {
        if (id == (jsid) cx->runtime->atomState.lengthAtom) {
            if (fp->argsobj && TEST_OVERRIDE_BIT(fp, ARGS_LENGTH))
                return OBJ_GET_PROPERTY(cx, fp->argsobj, id, vp);
            *vp = INT_TO_JSVAL((jsint) fp->argc);
        }
    }
    return JS_TRUE;
}

JSObject *
js_GetArgsObject(JSContext *cx, JSStackFrame *fp)
{
    JSObject *argsobj;

    /* Create an arguments object for fp only if it lacks one. */
    argsobj = fp->argsobj;
    if (argsobj)
        return argsobj;

    /* Link the new object to fp so it can get actual argument values. */
    argsobj = js_NewObject(cx, &js_ArgumentsClass, NULL, NULL);
    if (!argsobj || !JS_SetPrivate(cx, argsobj, fp)) {
        cx->newborn[GCX_OBJECT] = NULL;
        return NULL;
    }
    fp->argsobj = argsobj;
    return argsobj;
}

static JSBool
args_enumerate(JSContext *cx, JSObject *obj);

JSBool
js_PutArgsObject(JSContext *cx, JSStackFrame *fp)
{
    JSObject *argsobj;
    jsval bmapval, rval;
    JSBool ok;
    JSRuntime *rt;

    /*
     * Reuse args_enumerate here to reflect fp's actual arguments as indexed
     * elements of argsobj.  Do this first, before clearing and freeing the
     * deleted argument slot bitmap, because args_enumerate depends on that.
     */
    argsobj = fp->argsobj;
    ok = args_enumerate(cx, argsobj);

    /*
     * Now clear the deleted argument number bitmap slot and free the bitmap,
     * if one was actually created due to 'delete arguments[0]' or similar.
     */
    (void) JS_GetReservedSlot(cx, argsobj, 0, &bmapval);
    if (!JSVAL_IS_VOID(bmapval)) {
        JS_SetReservedSlot(cx, argsobj, 0, JSVAL_VOID);
        if (MAXARGS(fp) > JSVAL_INT_BITS)
            JS_free(cx, JSVAL_TO_PRIVATE(bmapval));
    }

    /*
     * Now get the prototype properties so we snapshot fp->fun and fp->argc
     * before fp goes away.
     */
    rt = cx->runtime;
    ok &= js_GetProperty(cx, argsobj, (jsid)rt->atomState.calleeAtom, &rval);
    ok &= js_SetProperty(cx, argsobj, (jsid)rt->atomState.calleeAtom, &rval);
    ok &= js_GetProperty(cx, argsobj, (jsid)rt->atomState.lengthAtom, &rval);
    ok &= js_SetProperty(cx, argsobj, (jsid)rt->atomState.lengthAtom, &rval);

    /*
     * Clear the private pointer to fp, which is about to go away (js_Invoke).
     * Do this last because the args_enumerate and js_GetProperty calls above
     * need to follow the private slot to find fp.
     */
    ok &= JS_SetPrivate(cx, argsobj, NULL);
    fp->argsobj = NULL;
    return ok;
}

static JSBool
args_delProperty(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    jsint slot;
    JSStackFrame *fp;

    if (!JSVAL_IS_INT(id))
        return JS_TRUE;
    fp = (JSStackFrame *)
         JS_GetInstancePrivate(cx, obj, &js_ArgumentsClass, NULL);
    if (!fp)
        return JS_TRUE;
    JS_ASSERT(fp->argsobj);

    slot = JSVAL_TO_INT(id);
    switch (slot) {
      case ARGS_CALLEE:
      case ARGS_LENGTH:
        SET_OVERRIDE_BIT(fp, slot);
        break;

      default:
        if ((uintN)slot < MAXARGS(fp) && !MarkArgDeleted(cx, fp, slot))
            return JS_FALSE;
        break;
    }
    return JS_TRUE;
}

static JSBool
args_getProperty(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    jsint slot;
    JSStackFrame *fp;

    if (!JSVAL_IS_INT(id))
        return JS_TRUE;
    fp = (JSStackFrame *)
         JS_GetInstancePrivate(cx, obj, &js_ArgumentsClass, NULL);
    if (!fp)
        return JS_TRUE;
    JS_ASSERT(fp->argsobj);

    slot = JSVAL_TO_INT(id);
    switch (slot) {
      case ARGS_CALLEE:
        if (!TEST_OVERRIDE_BIT(fp, slot))
            *vp = fp->argv ? fp->argv[-2] : OBJECT_TO_JSVAL(fp->fun->object);
        break;

      case ARGS_LENGTH:
        if (!TEST_OVERRIDE_BIT(fp, slot))
            *vp = INT_TO_JSVAL((jsint)fp->argc);
        break;

      default:
        if ((uintN)slot < MAXARGS(fp) && !ArgWasDeleted(cx, fp, slot))
            *vp = fp->argv[slot];
        break;
    }
    return JS_TRUE;
}

static JSBool
args_setProperty(JSContext *cx, JSObject *obj, jsval id, jsval *vp)
{
    JSStackFrame *fp;
    jsint slot;

    if (!JSVAL_IS_INT(id))
        return JS_TRUE;
    fp = (JSStackFrame *)
         JS_GetInstancePrivate(cx, obj, &js_ArgumentsClass, NULL);
    if (!fp)
        return JS_TRUE;
    JS_ASSERT(fp->argsobj);

    slot = JSVAL_TO_INT(id);
    switch (slot) {
      case ARGS_CALLEE:
      case ARGS_LENGTH:
        SET_OVERRIDE_BIT(fp, slot);
        break;

      default:
        if ((uintN)slot < MAXARGS(fp) && !ArgWasDeleted(cx, fp, slot))
            fp->argv[slot] = *vp;
        break;
    }
    return JS_TRUE;
}

static JSBool
args_resolve(JSContext *cx, JSObject *obj, jsval id, uintN flags,
             JSObject **objp)
{
    JSStackFrame *fp;
    uintN slot;
    JSString *str;
    JSAtom *atom;
    intN tinyid;
    jsval value;

    *objp = NULL;
    fp = (JSStackFrame *)
         JS_GetInstancePrivate(cx, obj, &js_ArgumentsClass, NULL);
    if (!fp)
        return JS_TRUE;
    JS_ASSERT(fp->argsobj);

    if (JSVAL_IS_INT(id)) {
        slot = JSVAL_TO_INT(id);
        if (slot < MAXARGS(fp) && !ArgWasDeleted(cx, fp, slot)) {
            /* XXX ECMA specs DontEnum, contrary to other array-like objects */
            if (!js_DefineProperty(cx, obj, (jsid) id, fp->argv[slot],
                                   args_getProperty, args_setProperty,
                                   JSVERSION_IS_ECMA(cx->version)
                                   ? 0
                                   : JSPROP_ENUMERATE,
                                   NULL)) {
                return JS_FALSE;
            }
            *objp = obj;
        }
    } else {