urbit/ent.c
2018-12-27 20:06:45 +00:00

43 lines
691 B
C

#include <ent/ent.h>
#if defined(ENT_URANDOM)
#warning "libent: using /dev/urandom..."
#include <assert.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
int
ent_getentropy(void* buf, size_t len)
{
int fd;
ssize_t ret;
char* cuf = buf;
assert(len <= 256);
if (-1 == (fd = open("/dev/urandom", O_RDONLY))) {
return -1;
}
while (len != 0 && (ret = read(fd, cuf, len)) != 0) {
if (ret == -1) {
if (errno == EINTR)
continue;
break;
}
len -= ret;
cuf += ret;
}
(void) close(fd);
if (ret == 0) {
ret = -1;
errno = EIO;
}
return ret < 0 ? ret : 0;
}
#endif /* ENT_USE_URANDOM */