Function kern_getfsstat

freebsd/kern/vfs_syscalls.c:424–583

* If (bufsize > 0 && bufseg == UIO_SYSSPACE) * The caller is responsible for freeing memory which will be allocated * in '*buf'. */

 *	in '*buf'.
 */
int
kern_getfsstat(struct thread *td, struct statfs **buf, size_t bufsize,
    size_t *countp, enum uio_seg bufseg, int mode)
{
	struct mount *mp, *nmp;
	struct statfs *sfsp, *sp, *sptmp, *tofree;
	size_t count, maxcount;
	int error;

	switch (mode) {
	case MNT_WAIT:
	case MNT_NOWAIT:
		break;
	default:
		if (bufseg == UIO_SYSSPACE)
			*buf = NULL;
		return (EINVAL);
	}
restart:
	maxcount = bufsize / sizeof(struct statfs);
	if (bufsize == 0) {
		sfsp = NULL;
		tofree = NULL;
	} else if (bufseg == UIO_USERSPACE) {
		sfsp = *buf;
		tofree = NULL;
	} else /* if (bufseg == UIO_SYSSPACE) */ {
		count = 0;
		mtx_lock(&mountlist_mtx);
		TAILQ_FOREACH(mp, &mountlist, mnt_list) {
			count++;
		}
		mtx_unlock(&mountlist_mtx);
		if (maxcount > count)
			maxcount = count;
		tofree = sfsp = *buf = malloc(maxcount * sizeof(struct statfs),
		    M_STATFS, M_WAITOK);
	}

	count = 0;

	/*
	 * If there is no target buffer they only want the count.
	 *
	 * This could be TAILQ_FOREACH but it is open-coded to match the original
	 * code below.
	 */
	if (sfsp == NULL) {
		mtx_lock(&mountlist_mtx);
		for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
			if (prison_canseemount(td->td_ucred, mp) != 0) {
				nmp = TAILQ_NEXT(mp, mnt_list);
				continue;
			}
#ifdef MAC
			if (mac_mount_check_stat(td->td_ucred, mp) != 0) {
				nmp = TAILQ_NEXT(mp, mnt_list);
				continue;