sidtab_context_to_sid
rc = sidtab_context_to_sid(sidtab, &context, sid);
rc = sidtab_context_to_sid(sidtab, &newcontext, out_sid);
rc = sidtab_context_to_sid(sidtab, &c->context[index], &sid);
rc = sidtab_context_to_sid(sidtab, &usercon, &sid);
rc = sidtab_context_to_sid(sidtab, &newcon, new_sid);
rc = sidtab_context_to_sid(sidtab, &ctx_new, sid);
int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid);