/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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 (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*      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.
 */

#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>
#include <sys/file.h>
#include <fs/fs_subr.h>
#include <c2/audit.h>
#include <sys/fcntl.h>

/*
 * Determine accessibility of file.
 */

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

static int
caccess(char *fname, int fmode, vnode_t *startvp)
{
        vnode_t *vp;
        cred_t *tmpcr;
        int error;
        int mode;
        int eok;
        cred_t *cr;
        int estale_retry = 0;

        if (fmode & ~(E_OK|R_OK|W_OK|X_OK))
                return (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 = lookupnameatcred(fname, UIO_USERSPACE, FOLLOW, NULLVPP, &vp,
            startvp, tmpcr)) {
                if ((error == ESTALE) && fs_need_estale_retry(estale_retry++))
                        goto lookup;
                if (!eok)
                        crfree(tmpcr);
                return (error);
        }

        if (mode) {
                error = VOP_ACCESS(vp, mode, 0, tmpcr, NULL);
                if (error) {
                        if ((error == ESTALE) &&
                            fs_need_estale_retry(estale_retry++)) {
                                VN_RELE(vp);
                                goto lookup;
                        }
                }
        }

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

int
faccessat(int fd, char *fname, int fmode, int flag)
{
        vnode_t *startvp;
        int error;

        if ((flag & ~AT_EACCESS) != 0)
                return (set_errno(EINVAL));

        if (fname == NULL)
                return (set_errno(EFAULT));
        if ((error = fgetstartvp(fd, fname, &startvp)) != 0)
                return (set_errno(error));
        if (AU_AUDITING() && startvp != NULL)
                audit_setfsat_path(1);

        /* Do not allow E_OK unless AT_EACCESS flag is set */
        fmode &= ~E_OK;
        if (flag & AT_EACCESS)
                fmode |= E_OK;

        error = caccess(fname, fmode, startvp);
        if (startvp != NULL)
                VN_RELE(startvp);
        if (error)
                return (set_errno(error));
        return (0);
}

int
access(char *fname, int fmode)
{
        return (faccessat(AT_FDCWD, fname, fmode, 0));
}