libdiskmgt/common/inuse_zpool.c

	inuse_zpool.c revision 3e1bd7a2aaeb6188caef90679b98088cfef1edc6
/*
 * 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"

/*
 * Attempt to dynamically link in the ZFS libzfs.so.1 so that we can
 * see if there are any ZFS zpools on any of the slices.
 */

#include <stdlib.h>
#include <stdio.h>
#include <strings.h>
#include <sys/param.h>
#include <sys/errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <thread.h>
#include <synch.h>
#include <dlfcn.h>
#include <link.h>
#include <ctype.h>

#include "libdiskmgt.h"
#include "disks_private.h"

/*
 * Pointers to libzfs.so functions that we dynamically resolve.
 */
static  int (*zfsdl_zpool_in_use)(int fd, char **desc, char **name);

static mutex_t          init_lock = DEFAULTMUTEX;
static rwlock_t         zpool_lock = DEFAULTRWLOCK;
static  int         initialized = 0;

static void *init_zpool();

int
inuse_zpool(char *slice, nvlist_t *attrs, int *errp)
{
    int     found = 0;
    char        *desc, *name;
    int     fd;

    *errp = 0;
    if (slice == NULL) {
        return (found);
    }

    (void) mutex_lock(&init_lock);

    /*
     * Dynamically load libzfs
     */
    if (!initialized) {
        if (!init_zpool()) {
            (void) mutex_unlock(&init_lock);
            return (found);
        }
        initialized = 1;
    }
    (void) mutex_unlock(&init_lock);
    (void) rw_rdlock(&zpool_lock);
    if ((fd = open(slice, O_RDONLY)) > 0) {
        if (zfsdl_zpool_in_use(fd, &desc, &name)) {
            libdiskmgt_add_str(attrs, DM_USED_BY,
                DM_USE_ZPOOL, errp);
            libdiskmgt_add_str(attrs, DM_USED_NAME,
                name, errp);
            found = 1;
        }
    }
    (void) rw_unlock(&zpool_lock);

    return (found);
}

/*
 * Try to dynamically link the zfs functions we need.
 */
static void*
init_zpool()
{
    void    *lh = NULL;

    if ((lh = dlopen("libzfs.so", RTLD_NOW)) == NULL) {
        return (lh);
    }
    /*
     * Instantiate the functions needed to get zpool configuration
     * data
     */
    if ((zfsdl_zpool_in_use = (int (*)(int, char **, char **))dlsym(lh,
        "zpool_in_use")) == NULL) {
        (void) dlclose(lh);
        return (NULL);
    }

    return (lh);
}