Function kern_getsockopt

freebsd/kern/uipc_syscalls.c:1306–1346

* Kernel version of getsockopt. * optval can be a userland or userspace. optlen is always a kernel pointer. */

 * optval can be a userland or userspace. optlen is always a kernel pointer.
 */
int
kern_getsockopt(struct thread *td, int s, int level, int name, void *val,
    enum uio_seg valseg, socklen_t *valsize)
{
	struct socket *so;
	struct file *fp;
	struct sockopt sopt;
	int error;

	if (val == NULL)
		*valsize = 0;
	if ((int)*valsize < 0)
		return (EINVAL);

	sopt.sopt_dir = SOPT_GET;
	sopt.sopt_level = level;
	sopt.sopt_name = name;
	sopt.sopt_val = val;
	sopt.sopt_valsize = (size_t)*valsize; /* checked non-negative above */
	switch (valseg) {
	case UIO_USERSPACE:
		sopt.sopt_td = td;
		break;
	case UIO_SYSSPACE:
		sopt.sopt_td = NULL;
		break;
	default:
		panic("kern_getsockopt called with bad valseg");
	}

	AUDIT_ARG_FD(s);
	error = getsock_cap(td, s, &cap_getsockopt_rights,
	    &fp, NULL, NULL);
	if (error == 0) {
		so = fp->f_data;
		error = sogetopt(so, &sopt);
		*valsize = sopt.sopt_valsize;
		fdrop(fp, td);
	}
	return (error);
}

/*
 * getsockname1() - Get socket name.