root/fs/xfs/support/uuid.c

DEFINITIONS

1. uuid_getnodeuniq
2. uuid_create_nil
3. uuid_is_nil
4. uuid_equal
5. uuid_hash64
6. uuid_table_insert
7. uuid_table_remove

/*
 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include <xfs.h>

static DEFINE_MUTEX(uuid_monitor);
static int      uuid_table_size;
static uuid_t   *uuid_table;

/* IRIX interpretation of an uuid_t */
typedef struct {
        __be32  uu_timelow;
        __be16  uu_timemid;
        __be16  uu_timehi;
        __be16  uu_clockseq;
        __be16  uu_node[3];
} xfs_uu_t;

/*
 * uuid_getnodeuniq - obtain the node unique fields of a UUID.
 *
 * This is not in any way a standard or condoned UUID function;
 * it just something that's needed for user-level file handles.
 */
void
uuid_getnodeuniq(uuid_t *uuid, int fsid [2])
{
        xfs_uu_t *uup = (xfs_uu_t *)uuid;

        fsid[0] = (be16_to_cpu(uup->uu_clockseq) << 16) |
                   be16_to_cpu(uup->uu_timemid);
        fsid[1] = be32_to_cpu(uup->uu_timelow);
}

void
uuid_create_nil(uuid_t *uuid)
{
        memset(uuid, 0, sizeof(*uuid));
}

int
uuid_is_nil(uuid_t *uuid)
{
        int     i;
        char    *cp = (char *)uuid;

        if (uuid == NULL)
                return 0;
        /* implied check of version number here... */
        for (i = 0; i < sizeof *uuid; i++)
                if (*cp++) return 0;    /* not nil */
        return 1;       /* is nil */
}

int
uuid_equal(uuid_t *uuid1, uuid_t *uuid2)
{
        return memcmp(uuid1, uuid2, sizeof(uuid_t)) ? 0 : 1;
}

/*
 * Given a 128-bit uuid, return a 64-bit value by adding the top and bottom
 * 64-bit words.  NOTE: This function can not be changed EVER.  Although
 * brain-dead, some applications depend on this 64-bit value remaining
 * persistent.  Specifically, DMI vendors store the value as a persistent
 * filehandle.
 */
__uint64_t
uuid_hash64(uuid_t *uuid)
{
        __uint64_t      *sp = (__uint64_t *)uuid;

        return sp[0] + sp[1];
}

int
uuid_table_insert(uuid_t *uuid)
{
        int     i, hole;

        mutex_lock(&uuid_monitor);
        for (i = 0, hole = -1; i < uuid_table_size; i++) {
                if (uuid_is_nil(&uuid_table[i])) {
                        hole = i;
                        continue;
                }
                if (uuid_equal(uuid, &uuid_table[i])) {
                        mutex_unlock(&uuid_monitor);
                        return 0;
                }
        }
        if (hole < 0) {
                uuid_table = kmem_realloc(uuid_table,
                        (uuid_table_size + 1) * sizeof(*uuid_table),
                        uuid_table_size  * sizeof(*uuid_table),
                        KM_SLEEP);
                hole = uuid_table_size++;
        }
        uuid_table[hole] = *uuid;
        mutex_unlock(&uuid_monitor);
        return 1;
}

void
uuid_table_remove(uuid_t *uuid)
{
        int     i;

        mutex_lock(&uuid_monitor);
        for (i = 0; i < uuid_table_size; i++) {
                if (uuid_is_nil(&uuid_table[i]))
                        continue;
                if (!uuid_equal(uuid, &uuid_table[i]))
                        continue;
                uuid_create_nil(&uuid_table[i]);
                break;
        }
        ASSERT(i < uuid_table_size);
        mutex_unlock(&uuid_monitor);
}