ref: f18c8b933e1519375a0f0cbdde031e2cf590abd7
dir: /sys/src/libc/9sys/truerand.c/
#include <u.h>
#include <libc.h>
ulong
truerand(void)
{
	ulong x;
	static int randfd = -1;
	if(randfd < 0)
		randfd = open("/dev/random", OREAD|OCEXEC);
	if(randfd < 0)
		sysfatal("can't open /dev/random");
	if(read(randfd, &x, sizeof(x)) != sizeof(x))
		sysfatal("can't read /dev/random");
	return x;
}