The explain_getchar_or_die function
is used to call the getchar(3) system
call. On failure an explanation will be
printed to stderr,
obtained from explain_getchar(3),
and then the process terminates
by calling exit(EXIT_FAILURE).
This function is intended to be used in a fashion
similar to the following example:
int c = explain_getchar_or_die();
Returns:
This function only returns on success.
On failure, prints an explanation and exits.