main: fix copy loop

fix potential infinite loop on a short read.

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

main.c

@@ -2557,11 +2557,13 @@ copy_fd_to_fd (int sfd, int dfd, char *buf, size_t buf_size)
         break;
 
       written = 0;
+      do
         {
           ret = TEMP_FAILURE_RETRY (write (dfd, buf + written, nread));
           if (ret < 0)
             return ret;
           nread -= ret;
+          written += ret;
         }
       while (nread);
     }