/**
* mnt_table_get_root_fs:
* @tb: mountinfo file (/proc/self/mountinfo)
* @root: returns pointer to the root filesystem (/)
*
* The function uses parent ID from mountinfo file to determine root filesystem
* (the filesystem with the smallest ID). The function is designed mostly for
* applications where is necessary to sort mountpoints by IDs to get the tree
* of the mountpoints (e.g. findmnt default output).
*
* If you're not sure than use
*
* mnt_table_find_target(tb, "/", MNT_ITER_BACKWARD);
*
* this is more robust and usable for arbitrary tab file (including fstab).
*
* Returns: 0 on success or less then zero case of error.
*/
int mnt_table_get_root_fs(struct libmnt_table *tb, struct libmnt_fs **root)
{
struct libmnt_iter itr;
struct libmnt_fs *fs;
int root_id = 0;
assert(tb);
assert(root);
if (!tb || !root)
return -EINVAL;
DBG(TAB, mnt_debug_h(tb, "lookup root fs"));
mnt_reset_iter(&itr, MNT_ITER_FORWARD);
while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
int id = mnt_fs_get_parent_id(fs);
if (!id)
break; /* @tab is not mountinfo file? */
if (!*root || id < root_id) {
*root = fs;
root_id = id;
}
}
return root_id ? 0 : -EINVAL;
}
/**
* mnt_table_get_root_fs:
* @tb: mountinfo file (/proc/self/mountinfo)
* @root: returns pointer to the root filesystem (/)
*
* The function uses the parent ID from the mountinfo file to determine the root filesystem
* (the filesystem with the smallest ID). The function is designed mostly for
* applications where it is necessary to sort mountpoints by IDs to get the tree
* of the mountpoints (e.g. findmnt default output).
*
* If you're not sure, then use
*
* mnt_table_find_target(tb, "/", MNT_ITER_BACKWARD);
*
* this is more robust and usable for arbitrary tab files (including fstab).
*
* Returns: 0 on success or negative number in case of error.
*/
int mnt_table_get_root_fs(struct libmnt_table *tb, struct libmnt_fs **root)
{
struct libmnt_iter itr;
struct libmnt_fs *fs;
int root_id = 0;
assert(tb);
assert(root);
if (!tb || !root || !is_mountinfo(tb))
return -EINVAL;
DBG(TAB, ul_debugobj(tb, "lookup root fs"));
*root = NULL;
mnt_reset_iter(&itr, MNT_ITER_FORWARD);
while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
int id = mnt_fs_get_parent_id(fs);
if (!*root || id < root_id) {
*root = fs;
root_id = id;
}
}
return *root ? 0 : -EINVAL;
}
/**
* mnt_table_next_child_fs:
* @tb: mountinfo file (/proc/self/mountinfo)
* @itr: iterator
* @parent: parental FS
* @chld: returns the next child filesystem
*
* Note that filesystems are returned in the order how was mounted (according to
* IDs in /proc/self/mountinfo).
*
* Returns: 0 on success, negative number in case of error or 1 at end of list.
*/
int mnt_table_next_child_fs(struct libmnt_table *tb, struct libmnt_iter *itr,
struct libmnt_fs *parent, struct libmnt_fs **chld)
{
struct libmnt_fs *fs;
int parent_id, lastchld_id = 0, chld_id = 0;
if (!tb || !itr || !parent)
return -EINVAL;
DBG(TAB, mnt_debug_h(tb, "lookup next child of '%s'",
mnt_fs_get_target(parent)));
parent_id = mnt_fs_get_id(parent);
if (!parent_id)
return -EINVAL;
/* get ID of the previously returned child */
if (itr->head && itr->p != itr->head) {
MNT_ITER_ITERATE(itr, fs, struct libmnt_fs, ents);
lastchld_id = mnt_fs_get_id(fs);
}
*chld = NULL;
mnt_reset_iter(itr, MNT_ITER_FORWARD);
while(mnt_table_next_fs(tb, itr, &fs) == 0) {
int id;
if (mnt_fs_get_parent_id(fs) != parent_id)
continue;
id = mnt_fs_get_id(fs);
/* avoid infinite loop. This only happens in rare cases
* such as in early userspace when the rootfs is its own parent */
if (id == parent_id)
continue;
if ((!lastchld_id || id > lastchld_id) &&
(!*chld || id < chld_id)) {
*chld = fs;
chld_id = id;
}
}
if (!chld_id)
return 1; /* end of iterator */
/* set the iterator to the @chld for the next call */
mnt_table_set_iter(tb, itr, *chld);
return 0;
}
