12.9.4 Foreign stream error handling

int Sferror(IOSTREAM *s)

Returns TRUE if the stream is in an error condition, FALSE if the stream is valid and in normal condition and -1 if the stream is invalid.

void Sclearerr(IOSTREAM *s)

Clear the error state of a stream. This includes the end-of-file state, pending warnings and errors and timeout.

int Sseterr(IOSTREAM *s, int which, const char *message)

Set an error or warning state on the stream. The which argument is one of SIO_WARN or SIO_FERR. This causes PL_release_stream() to print a message (SIO_WARN) or raise an exception (SIO_FERR).

int Sset_exception(IOSTREAM *s, term_t ex)

Associate a Prolog exception term with the stream or clear the associated exception if ex is 0 and set/clear the SIO_FERR condition on the stream. If an exception is assocated PL_release_stream() raises this exception.