form datei_umbenennen using lv_altpfad lv_neupfad type string. data: lv_eof_reached type c, lv_buffer(20480), lv_buflen type i. open dataset lv_altpfad for input in binary mode. if sy-subrc ne 0. raise open_input_file_failed. endif. open dataset lv_neupfad for output in binary mode. if sy-subrc ne 0. raise open_output_file_failed. endif. clear lv_eof_reached. do. clear lv_buffer. read dataset lv_altpfad into lv_buffer length lv_buflen. if sy-subrc = 4. lv_eof_reached = 'X'. elseif sy-subrc > 4. raise read_block_failed. endif. transfer lv_buffer to lv_neupfad length lv_buflen. if sy-subrc ne 0. raise write_block_failed. endif. if lv_eof_reached eq 'X'. exit. endif. enddo. close dataset lv_altpfad. close dataset lv_neupfad. if sy-subrc <> 0. raise close_output_file_failed. endif. delete dataset lv_altpfad. endform.