fd_free
sp->free = fd_free;
fd_free(b);
static int fd_free(BIO *data);
fd_free,
SLIST_HEAD(, freetable) fd_free;
SLIST_INSERT_HEAD(&fdp0->fd_free, ft, ft_next);
SLIST_FOREACH_SAFE(ft, &fdp0->fd_free, ft_next, tft)
SLIST_FOREACH(ft, &fdp0.fd_free, ft_next) {
SLIST_HEAD(, freetable) fd_free;