1 #include <u.h>
2 #include <libc.h>
3 
4 ulong
5 truerand(void)
6 {
7 	int i, n;
8 	uchar buf[sizeof(ulong)];
9 	static int randfd = -1;
10 
11 	if(randfd < 0){
12 		randfd = open("/dev/random", OREAD);
13 		fcntl(randfd, F_SETFD, FD_CLOEXEC);
14 	}
15 	if(randfd < 0)
16 		sysfatal("can't open /dev/random: %r");
17 	for(i=0; i<sizeof(buf); i += n)
18 		if((n = readn(randfd, buf+i, sizeof(buf)-i)) < 0)
19 			sysfatal("can't read /dev/random: %r");
20 	return *((ulong*)buf);
21 }