When an exception has been raised, the functions SP_query(),
SP_query_cut_fail() and SP_next_solution() return
SP_ERROR. To access the exception term (the argument
of the call to raise_exception/1), which is asserted when the
exception is raised, the function SP_exception_term() is used.
As a side-effect, the exception term is retracted, so if
your code wants to pass the exception term back to Prolog, it must
use the SP_raise_exception() function below. If an
exception term exists, SP_exception_term() retracts it and
stores it as the value of an SP_term_ref, which must exist prior
to the call and returns nonzero. Otherwise, it returns zero:
int SP_exception_term(SP_term_ref t)
To raise an exception from a C function called from Prolog, just call
SP_raise_exception(t) where t is the SP_term_ref
whose value is the exception term. The glue code will
detect that an exception has been raised, any value returned from the
function will be ignored, and the exception will be passed back to
Prolog:
void SP_raise_exception(SP_term_ref t)