(rr13): handle zero length bit strings

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@6880 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/krb5/n-fold.c

@@ -40,6 +40,9 @@ rr13(unsigned char *buf, size_t len)
     unsigned char *tmp;
     int bytes = (len + 7) / 8;
     int i;
+    if(len == 0)
+	return;
+    {
 	const int bits = 13 % len;
 	const int lbit = len % 8;
     
@@ -71,6 +74,7 @@ rr13(unsigned char *buf, size_t len)
 	    buf[i] = (tmp[b1] << s1) | (tmp[b2] >> s2);
 	}
 	free(tmp);
+    }
 }
 
 /* Add `b' to `a', both beeing one's complement numbers. */