common/syscall/access.c

	access.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/param.h>
#include <sys/isa_defs.h>
#include <sys/types.h>
#include <sys/sysmacros.h>
#include <sys/cred_impl.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/pathname.h>
#include <sys/vnode.h>
#include <sys/uio.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>

/*
 * Determine accessibility of file.
 */

#define E_OK    010 /* use effective ids */
#define R_OK    004
#define W_OK    002
#define X_OK    001

int
access(char *fname, int fmode)
{
    vnode_t *vp;
    cred_t *tmpcr;
    int error;
    int mode;
    int eok;
    cred_t *cr;

    if (fmode & ~(E_OK|R_OK|W_OK|X_OK))
        return (set_errno(EINVAL));

    mode = ((fmode & (R_OK|W_OK|X_OK)) << 6);

    cr = CRED();

    /* OK to use effective uid/gid, i.e., no need to crdup(CRED())? */
    eok = (fmode & E_OK) ||
        (cr->cr_uid == cr->cr_ruid && cr->cr_gid == cr->cr_rgid);

    if (eok)
        tmpcr = cr;
    else {
        tmpcr = crdup(cr);
        tmpcr->cr_uid = cr->cr_ruid;
        tmpcr->cr_gid = cr->cr_rgid;
        tmpcr->cr_ruid = cr->cr_uid;
        tmpcr->cr_rgid = cr->cr_gid;
    }

lookup:
    if (error = lookupname(fname, UIO_USERSPACE, FOLLOW, NULLVPP, &vp)) {
        if (error == ESTALE)
            goto lookup;
        if (!eok)
            crfree(tmpcr);
        return (set_errno(error));
    }

    if (mode) {
        error = VOP_ACCESS(vp, mode, 0, tmpcr);
        if (error) {
            if (error == ESTALE) {
                VN_RELE(vp);
                goto lookup;
            }
            (void) set_errno(error);
        }
    }

    if (!eok)
        crfree(tmpcr);
    VN_RELE(vp);
    return (error);
}