linux_kernel/include/uapi/linux/random.h

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
 * include/linux/random.h
 *
 * Include file for the random number generator.
 */

#ifndef _UAPI_LINUX_RANDOM_H
#define _UAPI_LINUX_RANDOM_H

#include <linux/types.h>
#include <linux/ioctl.h>
#include <linux/irqnr.h>

/* ioctl()'s for the random number generator */

/* Get the entropy count. */
#define RNDGETENTCNT	_IOR( 'R', 0x00, int )

/* Add to (or subtract from) the entropy count.  (Superuser only.) */
#define RNDADDTOENTCNT	_IOW( 'R', 0x01, int )

/* Get the contents of the entropy pool.  (Superuser only.) */
#define RNDGETPOOL	_IOR( 'R', 0x02, int [2] )

/* 
 * Write bytes into the entropy pool and add to the entropy count.
 * (Superuser only.)
 */
#define RNDADDENTROPY	_IOW( 'R', 0x03, int [2] )

/* Clear entropy count to 0.  (Superuser only.) */
#define RNDZAPENTCNT	_IO( 'R', 0x04 )

/* Clear the entropy pool and associated counters.  (Superuser only.) */
#define RNDCLEARPOOL	_IO( 'R', 0x06 )

struct rand_pool_info {
	int	entropy_count;
	int	buf_size;
	__u32	buf[0];
};

/*
 * Flags for getrandom(2)
 *
 * GRND_NONBLOCK	Don't block and return EAGAIN instead
 * GRND_RANDOM		Use the /dev/random pool instead of /dev/urandom
 */
#define GRND_NONBLOCK	0x0001
#define GRND_RANDOM	0x0002

#endif /* _UAPI_LINUX_RANDOM_H */