fr_caddr
if (f2->fr_caddr != NULL) {
f->fr_caddr = malloc(f->fr_dsize);
if (f->fr_caddr == NULL)
bcopy(f2->fr_caddr, f->fr_caddr, f->fr_dsize);
if (f->fr_caddr != NULL) {
f->fr_caddr = malloc(f->fr_dsize);
if (f->fr_caddr == NULL)
bcopy(f1->fr_caddr, f->fr_caddr, f->fr_dsize);
pp = (u_int *)(fp->fr_caddr + fp->fr_dsize);