c/io/fsetpos

Sets the file position indicator and the multibyte parsing state (if any) for the file stream according to the value pointed to by.

Besides establishing new parse state and position, a call to this function undoes the effects of ungetc and clears the end-of-file state, if it is set.

If a read or write error occurs, the error indicator (ferror) for the stream is set.

Return value
upon success, nonzero value otherwise.