On Thu, Apr 05, 2012 at 11:52:04PM +0200, Davidlohr Bueso wrote:
v> +/*
> + * Generate a stream of random nbytes into buf.
> + * Use /dev/urandom if possible, and if not,
> + * use glibc pseudo-random functions.
> + */
> +void random_get_bytes(void *buf, int nbytes)
> +{
> + int i, n = nbytes, fd = random_get_fd();
> + int lose_counter = 0;
> + unsigned char *cp = (unsigned char *) buf;
> +
> + if (fd >= 0) {
> + while (n > 0) {
> + i = read(fd, cp, n);
> + if (i <= 0) {
> + if (lose_counter++ > 16)
> + break;
> + continue;
> + }
> + n -= i;
> + cp += i;
> + lose_counter = 0;
> + }
> + }
> +
> + /*
> + * We do this all the time, but this is the only source of
> + * randomness if /dev/random/urandom is out to lunch.
> + */
> + for (cp = buf, i = 0; i < nbytes; i++)
> + *cp++ ^= (rand() >> 7) & 0xFF;
> +
> +#ifdef DO_JRAND_MIX
> + {
> + unsigned short tmp_seed[3];
> +
> + memcpy(tmp_seed, jrand_seed, sizeof(tmp_seed));
> + jrand_seed[2] = jrand_seed[2] ^ syscall(__NR_gettid);
> + for (cp = buf, i = 0; i < nbytes; i++)
> + *cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF;
> + memcpy(jrand_seed, tmp_seed,
> + sizeof(jrand_seed)-sizeof(unsigned short));
> + }
> +#endif
close(fd);
> +
> + return;
> +}
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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