return dir;
}
+ #endif
int dev_urandom(void *p, size_t n) {
- _cleanup_close_ int fd = -1;
+ static int have_syscall = -1;
+ int r, fd;
ssize_t k;
+ /* Gathers some randomness from the kernel. This call will
+ * never block, and will always return some data from the
+ * kernel, regardless if the random pool is fully initialized
+ * or not. It thus makes no guarantee for the quality of the
+ * returned entropy, but is good enough for or usual usecases
+ * of seeding the hash functions for hashtable */
+
+ /* Use the getrandom() syscall unless we know we don't have
+ * it, or when the requested size is too large for it. */
+ if (have_syscall != 0 || (size_t) (int) n != n) {
+ r = getrandom(p, n, GRND_NONBLOCK);
+ if (r == (int) n) {
+ have_syscall = true;
+ return 0;
+ }
+
+ if (r < 0) {
+ if (errno == ENOSYS)
+ /* we lack the syscall, continue with
+ * reading from /dev/urandom */
+ have_syscall = false;
+ else if (errno == EAGAIN)
+ /* not enough entropy for now. Let's
+ * remember to use the syscall the
+ * next time, again, but also read
+ * from /dev/urandom for now, which
+ * doesn't care about the current
+ * amount of entropy. */
+ have_syscall = true;
+ else
+ return -errno;
+ } else
+ /* too short read? */
+ return -EIO;
+ }
+
fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fd < 0)
return errno == ENOENT ? -ENOSYS : -errno;
projects / NetworkManager.git / commitdiff