The explain_setbuf_or_die function is used to call the
setbuf(3) system call. On failure an explanation will be printed to
stderr, obtained from the explain_setbuf(3) function, and
then the process terminates by calling exit(EXIT_FAILURE).
The explain_setbuf_on_error function is used to call the
setbuf(3) system call. On failure an explanation will be printed to
stderr, obtained from the explain_setbuf(3) function, but
still returns to the caller.
fp
The fp, exactly as to be passed to the setbuf(3) system call.
data
The data, exactly as to be passed to the setbuf(3) system call.
RETURN VALUE
The explain_setbuf_or_die function only returns on success, see
setbuf(3) for more information. On failure, prints an explanation
and exits, it does not return.
The explain_setbuf_on_error function always returns the value
return by the wrapped setbuf(3) system call.
EXAMPLE
The explain_setbuf_or_die function is intended to be used in a
fashion similar to the following example: