ref: de9a2c9aa2cf16c4bdca9a780f6c6ea2807301bb
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;
}