src/common/xrandom.c

/*****************************************************************************\
 *  xgetrandom.c - Slurm helper functions for randomness
 *****************************************************************************
 *  This file is part of Slurm, a resource management program.
 *  For details, see <https://slurm.schedmd.com/>.
 *  Please also read the included file: DISCLAIMER.
 *
 *  Slurm 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; either version 2 of the License, or (at your option)
 *  any later version.
 *
 *  In addition, as a special exception, the copyright holders give permission
 *  to link the code of portions of this program with the OpenSSL library under
 *  certain conditions as described in each individual source file, and
 *  distribute linked combinations including the two. You must obey the GNU
 *  General Public License in all respects for all of the code used other than
 *  OpenSSL. If you modify file(s) with this exception, you may extend this
 *  exception to your version of the file(s), but you are not obligated to do
 *  so. If you do not wish to do so, delete this exception statement from your
 *  version.  If you delete this exception statement from all source files in
 *  the program, then also delete it here.
 *
 *  Slurm is distributed in the hope that it will be useful, but WITHOUT ANY
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 *  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 Slurm; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA.
\*****************************************************************************/

#include "config.h"

#include <inttypes.h>
#include <stdbool.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>

#ifdef HAVE_GETRANDOM
#include <sys/random.h>
#endif

uint32_t xrandom(void)
{
	static bool no_seed = true;
	uint32_t random_value = 0;

#ifdef HAVE_GETRANDOM
	if (getrandom(&random_value, sizeof(random_value), 0) != -1)
		return random_value;
#endif
	if (no_seed) {
		srandom(time(NULL) + getpid());
		no_seed = false;
	}

	random_value = random();

	return random_value;
}