bcachefs-tools/include/linux/random.h

/*
 * include/linux/random.h
 *
 * Include file for the random number generator.
 */
#ifndef _LINUX_RANDOM_H
#define _LINUX_RANDOM_H

#include <unistd.h>
#include <sys/syscall.h>
#include <linux/bug.h>

#ifdef SYS_getrandom
static inline int getrandom(void *buf, size_t buflen, unsigned int flags)
{
	 return syscall(SYS_getrandom, buf, buflen, flags);
}
#else
extern int urandom_fd;

static inline int getrandom(void *buf, size_t buflen, unsigned int flags)
{
	return read(urandom_fd, buf, buflen);
}
#endif

static inline void get_random_bytes(void *buf, int nbytes)
{
	BUG_ON(getrandom(buf, nbytes, 0) != nbytes);
}

static inline void prandom_bytes(void *buf, int nbytes)
{
	return get_random_bytes(buf, nbytes);
}

#define get_random_type(type)				\
static inline type get_random_##type(void)		\
{							\
	type v;						\
							\
	get_random_bytes(&v, sizeof(v));		\
	return v;					\
}

get_random_type(int);
get_random_type(long);
get_random_type(u32);
get_random_type(u64);

#endif /* _LINUX_RANDOM_H */