/*
 * gen_uuid.c --- generate a DCE-compatible uuid
 *
 * Copyright (C) 1996, 1997, 1998, 1999 Theodore Ts'o.
 *
 * %Begin-Header%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, and the entire permission notice in its entirety,
 *    including the disclaimer of warranties.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
 * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 * %End-Header%
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include "uuidP.h"
#include "randutils.h"

#ifdef HAVE_TLS
#define THREAD_LOCAL static __thread
#else
#define THREAD_LOCAL static
#endif

/*
 * Try using the uuidd daemon to generate the UUID
 *
 * Returns 0 on success, non-zero on failure.
 */

void __uuid_generate_random(uuid_t out, int *num)
{
	uuid_t	buf;
	struct uuid uu;
	int i, n;

	if (!num || !*num)
		n = 1;
	else
		n = *num;

	for (i = 0; i < n; i++) {
		random_get_bytes(buf, sizeof(buf));
		uuid_unpack(buf, &uu);

		uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
		uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF)
			| 0x4000;
		uuid_pack(&uu, out);
		out += sizeof(uuid_t);
	}
}

void uuid_generate_random(uuid_t out)
{
	int	num = 1;
	/* No real reason to use the daemon for random uuid's -- yet */

	__uuid_generate_random(out, &num);
}

/*
 * Check whether good random source (/dev/random or /dev/urandom)
 * is available.
 */
static int have_random_source(void)
{
	return (access("/dev/random", R_OK) == 0 ||
		access("/dev/urandom", R_OK) == 0);
}

/*
 * This is the generic front-end to uuid_generate_random and
 * uuid_generate_time.  It uses uuid_generate_random only if
 * /dev/urandom is available, since otherwise we won't have
 * high-quality randomness.
 */
void uuid_generate(uuid_t out)
{
	if (have_random_source())
		uuid_generate_random(out);
}