linux/fs/xfs/support/uuid.c

/*
 * Copyright (c) 2000-2003 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 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.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */

#include <xfs.h>

static mutex_t	uuid_monitor;
static int	uuid_table_size;
static uuid_t	*uuid_table;

void
uuid_init(void)
{
	mutex_init(&uuid_monitor, MUTEX_DEFAULT, "uuid_monitor");
}

/*
 * 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])
{
	char	*uu = (char *)uuid;

	/* on IRIX, this function assumes big-endian fields within
	 * the uuid, so we use INT_GET to get the same result on
	 * little-endian systems
	 */

	fsid[0] = (INT_GET(*(u_int16_t*)(uu+8), ARCH_CONVERT) << 16) +
		   INT_GET(*(u_int16_t*)(uu+4), ARCH_CONVERT);
	fsid[1] =  INT_GET(*(u_int32_t*)(uu  ), ARCH_CONVERT);
}

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, PVFS);
	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, PVFS);
	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);
}