xfrd_open_xfrfile
df = xfrd_open_xfrfile(nsd, filenumber, "r+");
df = xfrd_open_xfrfile(nsd, filenumber, "r+");
df = xfrd_open_xfrfile(nsd, TASKLIST(task)->yesno, "r");
FILE* df = xfrd_open_xfrfile(nsd, filenumber, seq_nr?"a":"w");
FILE* xfrd_open_xfrfile(struct nsd* nsd, uint64_t number, char* mode);
if(!(df = xfrd_open_xfrfile(xfrd->nsd, xfr->xfrfilenumber, "r"))) {