write_behind
extern int write_behind(FILE *, int);
if (write_behind(file, convert) < 0) {
if (write_behind(file, convert) < 0) { /* flush last buffer */
if (write_behind(file, convert) < 0) /* flush it */
if (write_behind(file, pf->f_convert) < 0) {
if (write_behind(file, pf->f_convert) < 0) {