#include <u.h> #include <libc.h> ulong truerand(void) { int i, n; uchar buf[sizeof(ulong)]; static int randfd = -1; if(randfd < 0){ randfd = open("/dev/random", OREAD); if(randfd < 0) randfd = open("/dev/srandom", OREAD); /* OpenBSD */ if(randfd < 0) sysfatal("can't open /dev/random: %r"); fcntl(randfd, F_SETFD, FD_CLOEXEC); } for(i=0; i<sizeof(buf); i += n) if((n = readn(randfd, buf+i, sizeof(buf)-i)) < 0) sysfatal("can't read /dev/random: %r"); return *((ulong*)buf); }