common/syscall/getcwd.c

	getcwd.c revision 9a34c4c9ae95677a84d907ef0a331b13c85c6d5a
/*
 * 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 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

#include <sys/copyops.h>
#include <sys/errno.h>
#include <sys/kmem.h>
#include <sys/param.h>
#include <sys/pathname.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/vnode.h>

int
getcwd(char *buf, size_t buflen)
{
    int err;
    char *kbuf;
    size_t kbuflen;

    /*
     * The user should be able to specify any size buffer, but we don't want
     * to arbitrarily allocate huge kernel buffers just because the user
     * requests it.  So we'll start with MAXPATHLEN (which should hold any
     * normal path), and only increase it if we fail with ERANGE.
     */
    kbuflen = MIN(buflen, MAXPATHLEN);

    for (;;) {
        kbuf = kmem_alloc(kbuflen, KM_SLEEP);

        if (((err = dogetcwd(kbuf, kbuflen)) == 0) &&
            (copyout(kbuf, buf, strlen(kbuf) + 1) != 0))
            err = EFAULT;

        kmem_free(kbuf, kbuflen);

        if (err == ENAMETOOLONG) {
            /*
             * If the user's buffer really was too small, give up.
             * For some reason, getcwd() uses ERANGE for this case.
             */
            if (kbuflen == buflen) {
                err = ERANGE;
                break;
            }
            kbuflen = MIN(kbuflen * 2, buflen);
        } else {
            break;
        }
    }

    return ((err != 0) ? set_errno(err) : 0);
}