Adding upstream version 2.33.1.upstream/2.33.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2003 insertions, 0 deletions

diff --git a/libmount/src/tab.c b/libmount/src/tab.c
new file mode 100644
index 0000000..d80fb05
--- /dev/null
+++ b/libmount/src/tab.c
@@ -0,0 +1,2003 @@
+
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * This file is part of libmount from util-linux project.
+ *
+ * Copyright (C) 2008-2018 Karel Zak <kzak@redhat.com>
+ *
+ * libmount is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ */
+
+/**
+ * SECTION: table
+ * @title: Table of filesystems
+ * @short_description: container for entries from fstab, mtab or mountinfo
+ *
+ * Note that mnt_table_find_* functions are mount(8) compatible. These functions
+ * try to find an entry in more iterations, where the first attempt is always
+ * based on comparison with unmodified (non-canonicalized or un-evaluated)
+ * paths or tags. For example a fstab with two entries:
+ * <informalexample>
+ *   <programlisting>
+ *	LABEL=foo	/foo	auto   rw
+ *	/dev/foo	/foo	auto   rw
+ *  </programlisting>
+ * </informalexample>
+ *
+ * where both lines are used for the *same* device, then
+ * <informalexample>
+ *  <programlisting>
+ *	mnt_table_find_source(tb, "/dev/foo", &fs);
+ *  </programlisting>
+ * </informalexample>
+ * will returns the second line, and
+ * <informalexample>
+ *  <programlisting>
+ *	mnt_table_find_source(tb, "LABEL=foo", &fs);
+ *  </programlisting>
+ * </informalexample>
+ * will returns the first entry, and
+ * <informalexample>
+ *  <programlisting>
+ *	mnt_table_find_source(tb, "UUID=anyuuid", &fs);
+ *  </programlisting>
+ * </informalexample>
+ * will return the first entry (if UUID matches with the device).
+ */
+#include <blkid.h>
+
+#include "mountP.h"
+#include "strutils.h"
+#include "loopdev.h"
+#include "fileutils.h"
+#include "canonicalize.h"
+
+int is_mountinfo(struct libmnt_table *tb)
+{
+	struct libmnt_fs *fs;
+
+	if (!tb)
+		return 0;
+
+	fs = list_first_entry(&tb->ents, struct libmnt_fs, ents);
+	if (fs && mnt_fs_is_kernel(fs) && mnt_fs_get_root(fs))
+		return 1;
+
+	return 0;
+}
+
+/**
+ * mnt_new_table:
+ *
+ * The tab is a container for struct libmnt_fs entries that usually represents a fstab,
+ * mtab or mountinfo file from your system.
+ *
+ * See also mnt_table_parse_file().
+ *
+ * Returns: newly allocated tab struct.
+ */
+struct libmnt_table *mnt_new_table(void)
+{
+	struct libmnt_table *tb = NULL;
+
+	tb = calloc(1, sizeof(*tb));
+	if (!tb)
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "alloc"));
+	tb->refcount = 1;
+	INIT_LIST_HEAD(&tb->ents);
+	return tb;
+}
+
+/**
+ * mnt_reset_table:
+ * @tb: tab pointer
+ *
+ * Removes all entries (filesystems) from the table. The filesystems with zero
+ * reference count will be deallocated.
+ *
+ * Returns: 0 on success or negative number in case of error.
+ */
+int mnt_reset_table(struct libmnt_table *tb)
+{
+	if (!tb)
+		return -EINVAL;
+
+	DBG(TAB, ul_debugobj(tb, "reset"));
+
+	while (!list_empty(&tb->ents)) {
+		struct libmnt_fs *fs = list_entry(tb->ents.next,
+				                  struct libmnt_fs, ents);
+		mnt_table_remove_fs(tb, fs);
+	}
+
+	tb->nents = 0;
+	return 0;
+}
+
+/**
+ * mnt_ref_table:
+ * @tb: table pointer
+ *
+ * Increments reference counter.
+ */
+void mnt_ref_table(struct libmnt_table *tb)
+{
+	if (tb) {
+		tb->refcount++;
+		/*DBG(FS, ul_debugobj(tb, "ref=%d", tb->refcount));*/
+	}
+}
+
+/**
+ * mnt_unref_table:
+ * @tb: table pointer
+ *
+ * De-increments reference counter, on zero the @tb is automatically
+ * deallocated by mnt_free_table().
+ */
+void mnt_unref_table(struct libmnt_table *tb)
+{
+	if (tb) {
+		tb->refcount--;
+		/*DBG(FS, ul_debugobj(tb, "unref=%d", tb->refcount));*/
+		if (tb->refcount <= 0)
+			mnt_free_table(tb);
+	}
+}
+
+
+/**
+ * mnt_free_table:
+ * @tb: tab pointer
+ *
+ * Deallocates the table. This function does not care about reference count. Don't
+ * use this function directly -- it's better to use mnt_unref_table().
+ *
+ * The table entries (filesystems) are unreferenced by mnt_reset_table() and
+ * cache by mnt_unref_cache().
+ */
+void mnt_free_table(struct libmnt_table *tb)
+{
+	if (!tb)
+		return;
+
+	mnt_reset_table(tb);
+	DBG(TAB, ul_debugobj(tb, "free [refcount=%d]", tb->refcount));
+
+	mnt_unref_cache(tb->cache);
+	free(tb->comm_intro);
+	free(tb->comm_tail);
+	free(tb);
+}
+
+/**
+ * mnt_table_get_nents:
+ * @tb: pointer to tab
+ *
+ * Returns: number of entries in table.
+ */
+int mnt_table_get_nents(struct libmnt_table *tb)
+{
+	return tb ? tb->nents : 0;
+}
+
+/**
+ * mnt_table_is_empty:
+ * @tb: pointer to tab
+ *
+ * Returns: 1 if the table is without filesystems, or 0.
+ */
+int mnt_table_is_empty(struct libmnt_table *tb)
+{
+	return tb == NULL || list_empty(&tb->ents) ? 1 : 0;
+}
+
+/**
+ * mnt_table_set_userdata:
+ * @tb: pointer to tab
+ * @data: pointer to user data
+ *
+ * Sets pointer to the private user data.
+ *
+ * Returns: 0 on success or negative number in case of error.
+ */
+int mnt_table_set_userdata(struct libmnt_table *tb, void *data)
+{
+	if (!tb)
+		return -EINVAL;
+
+	tb->userdata = data;
+	return 0;
+}
+
+/**
+ * mnt_table_get_userdata:
+ * @tb: pointer to tab
+ *
+ * Returns: pointer to user's data.
+ */
+void *mnt_table_get_userdata(struct libmnt_table *tb)
+{
+	return tb ? tb->userdata : NULL;
+}
+
+/**
+ * mnt_table_enable_comments:
+ * @tb: pointer to tab
+ * @enable: TRUE or FALSE
+ *
+ * Enables parsing of comments.
+ *
+ * The initial (intro) file comment is accessible by
+ * mnt_table_get_intro_comment(). The intro and the comment of the first fstab
+ * entry has to be separated by blank line.  The filesystem comments are
+ * accessible by mnt_fs_get_comment(). The trailing fstab comment is accessible
+ * by mnt_table_get_trailing_comment().
+ *
+ * <informalexample>
+ *  <programlisting>
+ *	#
+ *	# Intro comment
+ *	#
+ *
+ *	# this comments belongs to the first fs
+ *	LABEL=foo /mnt/foo auto defaults 1 2
+ *	# this comments belongs to the second fs
+ *	LABEL=bar /mnt/bar auto defaults 1 2
+ *	# tailing comment
+ *  </programlisting>
+ * </informalexample>
+ */
+void mnt_table_enable_comments(struct libmnt_table *tb, int enable)
+{
+	if (tb)
+		tb->comms = enable;
+}
+
+/**
+ * mnt_table_with_comments:
+ * @tb: pointer to table
+ *
+ * Returns: 1 if comments parsing is enabled, or 0.
+ */
+int mnt_table_with_comments(struct libmnt_table *tb)
+{
+	assert(tb);
+	return tb ? tb->comms : 0;
+}
+
+/**
+ * mnt_table_get_intro_comment:
+ * @tb: pointer to tab
+ *
+ * Returns: initial comment in tb
+ */
+const char *mnt_table_get_intro_comment(struct libmnt_table *tb)
+{
+	return tb ? tb->comm_intro : NULL;
+}
+
+/**
+ * mnt_table_set_into_comment:
+ * @tb: pointer to tab
+ * @comm: comment or NULL
+ *
+ * Sets the initial comment in tb.
+ *
+ * Returns: 0 on success or negative number in case of error.
+ */
+int mnt_table_set_intro_comment(struct libmnt_table *tb, const char *comm)
+{
+	return strdup_to_struct_member(tb, comm_intro, comm);
+}
+
+/**
+ * mnt_table_append_into_comment:
+ * @tb: pointer to tab
+ * @comm: comment of NULL
+ *
+ * Appends the initial comment in tb.
+ *
+ * Returns: 0 on success or negative number in case of error.
+ */
+int mnt_table_append_intro_comment(struct libmnt_table *tb, const char *comm)
+{
+	if (!tb)
+		return -EINVAL;
+	return append_string(&tb->comm_intro, comm);
+}
+
+/**
+ * mnt_table_get_trailing_comment:
+ * @tb: pointer to tab
+ *
+ * Returns: table trailing comment
+ */
+const char *mnt_table_get_trailing_comment(struct libmnt_table *tb)
+{
+	return tb ? tb->comm_tail : NULL;
+}
+
+/**
+ * mnt_table_set_trailing_comment
+ * @tb: pointer to tab
+ * @comm: comment string
+ *
+ * Sets the trailing comment in table.
+ *
+ * Returns: 0 on success or negative number in case of error.
+ */
+int mnt_table_set_trailing_comment(struct libmnt_table *tb, const char *comm)
+{
+	return strdup_to_struct_member(tb, comm_tail, comm);
+}
+
+/**
+ * mnt_table_append_trailing_comment:
+ * @tb: pointer to tab
+ * @comm: comment of NULL
+ *
+ * Appends to the trailing table comment.
+ *
+ * Returns: 0 on success or negative number in case of error.
+ */
+int mnt_table_append_trailing_comment(struct libmnt_table *tb, const char *comm)
+{
+	if (!tb)
+		return -EINVAL;
+	return append_string(&tb->comm_tail, comm);
+}
+
+/**
+ * mnt_table_set_cache:
+ * @tb: pointer to tab
+ * @mpc: pointer to struct libmnt_cache instance
+ *
+ * Sets up a cache for canonicalized paths and evaluated tags (LABEL/UUID). The
+ * cache is recommended for mnt_table_find_*() functions.
+ *
+ * The cache could be shared between more tabs. Be careful when you share the
+ * same cache between more threads -- currently the cache does not provide any
+ * locking method.
+ *
+ * This function increments cache reference counter. It's recommended to use
+ * mnt_unref_cache() after mnt_table_set_cache() if you want to keep the cache
+ * referenced by @tb only.
+ *
+ * See also mnt_new_cache().
+ *
+ * Returns: 0 on success or negative number in case of error.
+ */
+int mnt_table_set_cache(struct libmnt_table *tb, struct libmnt_cache *mpc)
+{
+	if (!tb)
+		return -EINVAL;
+
+	mnt_ref_cache(mpc);			/* new */
+	mnt_unref_cache(tb->cache);		/* old */
+	tb->cache = mpc;
+	return 0;
+}
+
+/**
+ * mnt_table_get_cache:
+ * @tb: pointer to tab
+ *
+ * Returns: pointer to struct libmnt_cache instance or NULL.
+ */
+struct libmnt_cache *mnt_table_get_cache(struct libmnt_table *tb)
+{
+	return tb ? tb->cache : NULL;
+}
+
+/**
+ * mnt_table_add_fs:
+ * @tb: tab pointer
+ * @fs: new entry
+ *
+ * Adds a new entry to tab and increment @fs reference counter. Don't forget to
+ * use mnt_unref_fs() after mnt_table_add_fs() you want to keep the @fs
+ * referenced by the table only.
+ *
+ * Returns: 0 on success or negative number in case of error.
+ */
+int mnt_table_add_fs(struct libmnt_table *tb, struct libmnt_fs *fs)
+{
+	if (!tb || !fs)
+		return -EINVAL;
+
+	mnt_ref_fs(fs);
+	list_add_tail(&fs->ents, &tb->ents);
+	tb->nents++;
+
+	DBG(TAB, ul_debugobj(tb, "add entry: %s %s",
+			mnt_fs_get_source(fs), mnt_fs_get_target(fs)));
+	return 0;
+}
+
+/**
+ * mnt_table_remove_fs:
+ * @tb: tab pointer
+ * @fs: new entry
+ *
+ * Removes the @fs from the table and de-increment reference counter of the @fs. The
+ * filesystem with zero reference counter will be deallocated. Don't forget to use
+ * mnt_ref_fs() before call mnt_table_remove_fs() if you want to use @fs later.
+ *
+ * Returns: 0 on success or negative number in case of error.
+ */
+int mnt_table_remove_fs(struct libmnt_table *tb, struct libmnt_fs *fs)
+{
+	if (!tb || !fs)
+		return -EINVAL;
+
+	list_del(&fs->ents);
+	INIT_LIST_HEAD(&fs->ents);	/* otherwise FS still points to the list */
+
+	mnt_unref_fs(fs);
+	tb->nents--;
+	return 0;
+}
+
+static inline struct libmnt_fs *get_parent_fs(struct libmnt_table *tb, struct libmnt_fs *fs)
+{
+	struct libmnt_iter itr;
+	struct libmnt_fs *x;
+	int parent_id = mnt_fs_get_parent_id(fs);
+
+	mnt_reset_iter(&itr, MNT_ITER_FORWARD);
+	while (mnt_table_next_fs(tb, &itr, &x) == 0) {
+		if (mnt_fs_get_id(x) == parent_id)
+			return x;
+	}
+
+	return NULL;
+}
+
+/**
+ * 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 with parent ID missing
+ * in the table). 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;
+
+	if (!tb || !root || !is_mountinfo(tb))
+		return -EINVAL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup root fs"));
+
+	*root = NULL;
+
+	/* get smallest possible ID from the table */
+	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;
+		}
+	}
+
+	/* go to the root node by "parent_id -> id" relation */
+	while (*root) {
+		struct libmnt_fs *x = get_parent_fs(tb, *root);
+		if (!x || x == *root)
+			break;
+		DBG(TAB, ul_debugobj(tb, " messy mountinfo, walk to %s", mnt_fs_get_target(x)));
+		*root = x;
+	}
+
+	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 of mounting (according to
+ * IDs in /proc/self/mountinfo).
+ *
+ * Returns: 0 on success, negative number in case of error or 1 at the 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 || !is_mountinfo(tb))
+		return -EINVAL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup next child of '%s'",
+				mnt_fs_get_target(parent)));
+
+	parent_id = mnt_fs_get_id(parent);
+
+	/* 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 an 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)
+		return 1;	/* end of iterator */
+
+	/* set the iterator to the @chld for the next call */
+	mnt_table_set_iter(tb, itr, *chld);
+
+	return 0;
+}
+
+/**
+ * mnt_table_next_fs:
+ * @tb: tab pointer
+ * @itr: iterator
+ * @fs: returns the next tab entry
+ *
+ * Returns: 0 on success, negative number in case of error or 1 at the end of list.
+ *
+ * Example:
+ * <informalexample>
+ *   <programlisting>
+ *	while(mnt_table_next_fs(tb, itr, &fs) == 0) {
+ *		const char *dir = mnt_fs_get_target(fs);
+ *		printf("mount point: %s\n", dir);
+ *	}
+ *   </programlisting>
+ * </informalexample>
+ *
+ * lists all mountpoints from fstab in reverse order.
+ */
+int mnt_table_next_fs(struct libmnt_table *tb, struct libmnt_iter *itr, struct libmnt_fs **fs)
+{
+	int rc = 1;
+
+	if (!tb || !itr || !fs)
+		return -EINVAL;
+	*fs = NULL;
+
+	if (!itr->head)
+		MNT_ITER_INIT(itr, &tb->ents);
+	if (itr->p != itr->head) {
+		MNT_ITER_ITERATE(itr, *fs, struct libmnt_fs, ents);
+		rc = 0;
+	}
+
+	return rc;
+}
+
+/**
+ * mnt_table_first_fs:
+ * @tb: tab pointer
+ * @fs: returns the first tab entry
+ *
+ * Returns: 0 on success, negative number in case of error or 1 at the end of list.
+ */
+int mnt_table_first_fs(struct libmnt_table *tb, struct libmnt_fs **fs)
+{
+	if (!tb || !fs)
+		return -EINVAL;
+	if (list_empty(&tb->ents))
+		return 1;
+	*fs = list_first_entry(&tb->ents, struct libmnt_fs, ents);
+	return 0;
+}
+
+/**
+ * mnt_table_last_fs:
+ * @tb: tab pointer
+ * @fs: returns the last tab entry
+ *
+ * Returns: 0 on success, negative number in case of error or 1 at the end of list.
+ */
+int mnt_table_last_fs(struct libmnt_table *tb, struct libmnt_fs **fs)
+{
+	if (!tb || !fs)
+		return -EINVAL;
+	if (list_empty(&tb->ents))
+		return 1;
+	*fs = list_last_entry(&tb->ents, struct libmnt_fs, ents);
+	return 0;
+}
+
+/**
+ * mnt_table_find_next_fs:
+ * @tb: table
+ * @itr: iterator
+ * @match_func: function returning 1 or 0
+ * @userdata: extra data for match_func
+ * @fs: returns pointer to the next matching table entry
+ *
+ * This function allows searching in @tb.
+ *
+ * Returns: negative number in case of error, 1 at end of table or 0 o success.
+ */
+int mnt_table_find_next_fs(struct libmnt_table *tb, struct libmnt_iter *itr,
+		int (*match_func)(struct libmnt_fs *, void *), void *userdata,
+		struct libmnt_fs **fs)
+{
+	if (!tb || !itr || !fs || !match_func)
+		return -EINVAL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup next fs"));
+
+	if (!itr->head)
+		MNT_ITER_INIT(itr, &tb->ents);
+
+	do {
+		if (itr->p != itr->head)
+			MNT_ITER_ITERATE(itr, *fs, struct libmnt_fs, ents);
+		else
+			break;			/* end */
+
+		if (match_func(*fs, userdata))
+			return 0;
+	} while(1);
+
+	*fs = NULL;
+	return 1;
+}
+
+static int mnt_table_move_parent(struct libmnt_table *tb, int oldid, int newid)
+{
+	struct libmnt_iter itr;
+	struct libmnt_fs *fs;
+
+	if (!tb)
+		return -EINVAL;
+	if (list_empty(&tb->ents))
+		return 0;
+
+	DBG(TAB, ul_debugobj(tb, "moving parent ID from %d -> %d", oldid, newid));
+	mnt_reset_iter(&itr, MNT_ITER_FORWARD);
+
+	while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
+		if (fs->parent == oldid)
+			fs->parent = newid;
+	}
+	return 0;
+}
+
+/**
+ * mnt_table_uniq_fs:
+ * @tb: table
+ * @flags: MNT_UNIQ_*
+ * @cmp: function to compare filesystems
+ *
+ * This function de-duplicate the @tb, but does not change order of the
+ * filesystems. The @cmp function has to return 0 if the filesystems are
+ * equal, otherwise non-zero.
+ *
+ * The default is to keep in the table later mounted filesystems (function uses
+ * backward mode iterator).
+ *
+ * @MNT_UNIQ_FORWARD:  remove later mounted filesystems
+ * @MNT_UNIQ_KEEPTREE: keep parent->id relationship still valid
+ *
+ * Returns: negative number in case of error, or 0 o success.
+ */
+int mnt_table_uniq_fs(struct libmnt_table *tb, int flags,
+				int (*cmp)(struct libmnt_table *,
+					   struct libmnt_fs *,
+					   struct libmnt_fs *))
+{
+	struct libmnt_iter itr;
+	struct libmnt_fs *fs;
+	int direction = MNT_ITER_BACKWARD;
+
+	if (!tb || !cmp)
+		return -EINVAL;
+	if (list_empty(&tb->ents))
+		return 0;
+
+	if (flags & MNT_UNIQ_FORWARD)
+		direction = MNT_ITER_FORWARD;
+
+	DBG(TAB, ul_debugobj(tb, "de-duplicate"));
+	mnt_reset_iter(&itr, direction);
+
+	if ((flags & MNT_UNIQ_KEEPTREE) && !is_mountinfo(tb))
+		flags &= ~MNT_UNIQ_KEEPTREE;
+
+	while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
+		int want = 1;
+		struct libmnt_iter xtr;
+		struct libmnt_fs *x;
+
+		mnt_reset_iter(&xtr, direction);
+		while (want && mnt_table_next_fs(tb, &xtr, &x) == 0) {
+			if (fs == x)
+				break;
+			want = cmp(tb, x, fs) != 0;
+		}
+
+		if (!want) {
+			if (flags & MNT_UNIQ_KEEPTREE)
+				mnt_table_move_parent(tb, mnt_fs_get_id(fs),
+							  mnt_fs_get_parent_id(fs));
+
+			DBG(TAB, ul_debugobj(tb, "remove duplicate %s",
+						mnt_fs_get_target(fs)));
+			mnt_table_remove_fs(tb, fs);
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * mnt_table_set_iter:
+ * @tb: tab pointer
+ * @itr: iterator
+ * @fs: tab entry
+ *
+ * Sets @iter to the position of @fs in the file @tb.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_table_set_iter(struct libmnt_table *tb, struct libmnt_iter *itr, struct libmnt_fs *fs)
+{
+	if (!tb || !itr || !fs)
+		return -EINVAL;
+
+	MNT_ITER_INIT(itr, &tb->ents);
+	itr->p = &fs->ents;
+
+	return 0;
+}
+
+/**
+ * mnt_table_find_mountpoint:
+ * @tb: tab pointer
+ * @path: directory
+ * @direction: MNT_ITER_{FORWARD,BACKWARD}
+ *
+ * Same as mnt_get_mountpoint(), except this function does not rely on
+ * st_dev numbers.
+ *
+ * Returns: a tab entry or NULL.
+ */
+struct libmnt_fs *mnt_table_find_mountpoint(struct libmnt_table *tb,
+					    const char *path,
+					    int direction)
+{
+	char *mnt;
+	struct stat st;
+
+	if (!tb || !path || !*path)
+		return NULL;
+	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup MOUNTPOINT: '%s'", path));
+
+	if (mnt_stat_mountpoint(path, &st))
+		return NULL;
+
+	mnt = strdup(path);
+	if (!mnt)
+		return NULL;
+
+	do {
+		char *p;
+		struct libmnt_fs *fs;
+
+		fs = mnt_table_find_target(tb, mnt, direction);
+		if (fs) {
+			free(mnt);
+			return fs;
+		}
+
+		p = stripoff_last_component(mnt);
+		if (!p)
+			break;
+	} while (mnt && *(mnt + 1) != '\0');
+
+	free(mnt);
+	return mnt_table_find_target(tb, "/", direction);
+}
+
+/**
+ * mnt_table_find_target:
+ * @tb: tab pointer
+ * @path: mountpoint directory
+ * @direction: MNT_ITER_{FORWARD,BACKWARD}
+ *
+ * Try to lookup an entry in the given tab, three iterations are possible, the first
+ * with @path, the second with realpath(@path) and the third with realpath(@path)
+ * against realpath(fs->target). The 2nd and 3rd iterations are not performed when
+ * the @tb cache is not set (see mnt_table_set_cache()). If
+ * mnt_cache_set_targets(cache, mtab) was called, the 3rd iteration skips any
+ * @fs->target found in @mtab (see mnt_resolve_target()).
+ *
+ * Returns: a tab entry or NULL.
+ */
+struct libmnt_fs *mnt_table_find_target(struct libmnt_table *tb, const char *path, int direction)
+{
+	struct libmnt_iter itr;
+	struct libmnt_fs *fs = NULL;
+	char *cn;
+
+	if (!tb || !path || !*path)
+		return NULL;
+	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup TARGET: '%s'", path));
+
+	/* native @target */
+	mnt_reset_iter(&itr, direction);
+	while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+		if (mnt_fs_streq_target(fs, path))
+			return fs;
+	}
+
+	/* try absolute path */
+	if (is_relative_path(path) && (cn = absolute_path(path))) {
+		DBG(TAB, ul_debugobj(tb, "lookup absolute TARGET: '%s'", cn));
+		mnt_reset_iter(&itr, direction);
+		while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
+			if (mnt_fs_streq_target(fs, cn)) {
+				free(cn);
+				return fs;
+			}
+		}
+		free(cn);
+	}
+
+	if (!tb->cache || !(cn = mnt_resolve_path(path, tb->cache)))
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup canonical TARGET: '%s'", cn));
+
+	/* canonicalized paths in struct libmnt_table */
+	mnt_reset_iter(&itr, direction);
+	while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+		if (mnt_fs_streq_target(fs, cn))
+			return fs;
+	}
+
+	/* non-canonical path in struct libmnt_table
+	 * -- note that mountpoint in /proc/self/mountinfo is already
+	 *    canonicalized by the kernel
+	 */
+	mnt_reset_iter(&itr, direction);
+	while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+		char *p;
+
+		if (!fs->target
+		    || mnt_fs_is_swaparea(fs)
+		    || mnt_fs_is_kernel(fs)
+		    || (*fs->target == '/' && *(fs->target + 1) == '\0'))
+		       continue;
+
+		p = mnt_resolve_target(fs->target, tb->cache);
+		/* both canonicalized, strcmp() is fine here */
+		if (p && strcmp(cn, p) == 0)
+			return fs;
+	}
+	return NULL;
+}
+
+/**
+ * mnt_table_find_srcpath:
+ * @tb: tab pointer
+ * @path: source path (devname or dirname) or NULL
+ * @direction: MNT_ITER_{FORWARD,BACKWARD}
+ *
+ * Try to lookup an entry in the given tab, four iterations are possible, the first
+ * with @path, the second with realpath(@path), the third with tags (LABEL, UUID, ..)
+ * from @path and the fourth with realpath(@path) against realpath(entry->srcpath).
+ *
+ * The 2nd, 3rd and 4th iterations are not performed when the @tb cache is not
+ * set (see mnt_table_set_cache()).
+ *
+ * For btrfs returns tab entry for default id.
+ *
+ * Note that NULL is a valid source path; it will be replaced with "none". The
+ * "none" is used in /proc/{mounts,self/mountinfo} for pseudo filesystems.
+ *
+ * Returns: a tab entry or NULL.
+ */
+struct libmnt_fs *mnt_table_find_srcpath(struct libmnt_table *tb, const char *path, int direction)
+{
+	struct libmnt_iter itr;
+	struct libmnt_fs *fs = NULL;
+	int ntags = 0, nents;
+	char *cn;
+	const char *p;
+
+	if (!tb || !path || !*path)
+		return NULL;
+	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup SRCPATH: '%s'", path));
+
+	/* native paths */
+	mnt_reset_iter(&itr, direction);
+
+	while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+
+		if (mnt_fs_streq_srcpath(fs, path)) {
+#ifdef HAVE_BTRFS_SUPPORT
+			if (fs->fstype && !strcmp(fs->fstype, "btrfs")) {
+				uint64_t default_id = btrfs_get_default_subvol_id(mnt_fs_get_target(fs));
+				char *val;
+				size_t len;
+
+				if (default_id == UINT64_MAX)
+					DBG(TAB, ul_debug("not found btrfs volume setting"));
+
+				else if (mnt_fs_get_option(fs, "subvolid", &val, &len) == 0) {
+					uint64_t subvol_id;
+
+					if (mnt_parse_offset(val, len, &subvol_id)) {
+						DBG(TAB, ul_debugobj(tb, "failed to parse subvolid="));
+						continue;
+					}
+					if (subvol_id != default_id)
+						continue;
+				}
+			}
+#endif /* HAVE_BTRFS_SUPPORT */
+			return fs;
+		}
+		if (mnt_fs_get_tag(fs, NULL, NULL) == 0)
+			ntags++;
+	}
+
+	if (!path || !tb->cache || !(cn = mnt_resolve_path(path, tb->cache)))
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup canonical SRCPATH: '%s'", cn));
+
+	nents = mnt_table_get_nents(tb);
+
+	/* canonicalized paths in struct libmnt_table */
+	if (ntags < nents) {
+		mnt_reset_iter(&itr, direction);
+		while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+			if (mnt_fs_streq_srcpath(fs, cn))
+				return fs;
+		}
+	}
+
+	/* evaluated tag */
+	if (ntags) {
+		int rc = mnt_cache_read_tags(tb->cache, cn);
+
+		mnt_reset_iter(&itr, direction);
+
+		if (rc == 0) {
+			/* @path's TAGs are in the cache */
+			while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+				const char *t, *v;
+
+				if (mnt_fs_get_tag(fs, &t, &v))
+					continue;
+
+				if (mnt_cache_device_has_tag(tb->cache, cn, t, v))
+					return fs;
+			}
+		} else if (rc < 0 && errno == EACCES) {
+			/* @path is inaccessible, try evaluating all TAGs in @tb
+			 * by udev symlinks -- this could be expensive on systems
+			 * with a huge fstab/mtab */
+			 while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+				 const char *t, *v, *x;
+				 if (mnt_fs_get_tag(fs, &t, &v))
+					 continue;
+				 x = mnt_resolve_tag(t, v, tb->cache);
+
+				 /* both canonicalized, strcmp() is fine here */
+				 if (x && strcmp(x, cn) == 0)
+					 return fs;
+			 }
+		}
+	}
+
+	/* non-canonicalized paths in struct libmnt_table */
+	if (ntags <= nents) {
+		mnt_reset_iter(&itr, direction);
+		while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+			if (mnt_fs_is_netfs(fs) || mnt_fs_is_pseudofs(fs))
+				continue;
+			p = mnt_fs_get_srcpath(fs);
+			if (p)
+				p = mnt_resolve_path(p, tb->cache);
+
+			/* both canonicalized, strcmp() is fine here */
+			if (p && strcmp(p, cn) == 0)
+				return fs;
+		}
+	}
+
+	return NULL;
+}
+
+
+/**
+ * mnt_table_find_tag:
+ * @tb: tab pointer
+ * @tag: tag name (e.g "LABEL", "UUID", ...)
+ * @val: tag value
+ * @direction: MNT_ITER_{FORWARD,BACKWARD}
+ *
+ * Try to lookup an entry in the given tab, the first attempt is to lookup by @tag and
+ * @val, for the second attempt the tag is evaluated (converted to the device
+ * name) and mnt_table_find_srcpath() is performed. The second attempt is not
+ * performed when @tb cache is not set (see mnt_table_set_cache()).
+
+ * Returns: a tab entry or NULL.
+ */
+struct libmnt_fs *mnt_table_find_tag(struct libmnt_table *tb, const char *tag,
+			const char *val, int direction)
+{
+	struct libmnt_iter itr;
+	struct libmnt_fs *fs = NULL;
+
+	if (!tb || !tag || !*tag || !val)
+		return NULL;
+	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup by TAG: %s %s", tag, val));
+
+	/* look up by TAG */
+	mnt_reset_iter(&itr, direction);
+	while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+		if (fs->tagname && fs->tagval &&
+		    strcmp(fs->tagname, tag) == 0 &&
+		    strcmp(fs->tagval, val) == 0)
+			return fs;
+	}
+
+	if (tb->cache) {
+		/* look up by device name */
+		char *cn = mnt_resolve_tag(tag, val, tb->cache);
+		if (cn)
+			return mnt_table_find_srcpath(tb, cn, direction);
+	}
+	return NULL;
+}
+
+/**
+ * mnt_table_find_target_with_option:
+ * @tb: tab pointer
+ * @path: mountpoint directory
+ * @option: option name (e.g "subvol", "subvolid", ...)
+ * @val: option value or NULL
+ * @direction: MNT_ITER_{FORWARD,BACKWARD}
+ *
+ * Try to lookup an entry in the given tab that matches combination of @path
+ * and @option. In difference to mnt_table_find_target(), only @path iteration
+ * is done. No lookup by device name, no canonicalization.
+ *
+ * Returns: a tab entry or NULL.
+ *
+ * Since: 2.28
+ */
+struct libmnt_fs *mnt_table_find_target_with_option(
+			struct libmnt_table *tb, const char *path,
+			const char *option, const char *val, int direction)
+{
+	struct libmnt_iter itr;
+	struct libmnt_fs *fs = NULL;
+	char *optval = NULL;
+	size_t optvalsz = 0, valsz = val ? strlen(val) : 0;
+
+	if (!tb || !path || !*path || !option || !*option || !val)
+		return NULL;
+	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup TARGET: '%s' with OPTION %s %s", path, option, val));
+
+	/* look up by native @target with OPTION */
+	mnt_reset_iter(&itr, direction);
+	while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
+		if (mnt_fs_streq_target(fs, path)
+		    && mnt_fs_get_option(fs, option, &optval, &optvalsz) == 0
+		    && (!val || (optvalsz == valsz
+				 && strncmp(optval, val, optvalsz) == 0)))
+			return fs;
+	}
+	return NULL;
+}
+
+/**
+ * mnt_table_find_source:
+ * @tb: tab pointer
+ * @source: TAG or path
+ * @direction: MNT_ITER_{FORWARD,BACKWARD}
+ *
+ * This is a high-level API for mnt_table_find_{srcpath,tag}. You needn't care
+ * about the @source format (device, LABEL, UUID, ...). This function parses
+ * the @source and calls mnt_table_find_tag() or mnt_table_find_srcpath().
+ *
+ * Returns: a tab entry or NULL.
+ */
+struct libmnt_fs *mnt_table_find_source(struct libmnt_table *tb,
+					const char *source, int direction)
+{
+	struct libmnt_fs *fs;
+	char *t = NULL, *v = NULL;
+
+	if (!tb)
+		return NULL;
+	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup SOURCE: '%s'", source));
+
+	if (blkid_parse_tag_string(source, &t, &v) || !mnt_valid_tagname(t))
+		fs = mnt_table_find_srcpath(tb, source, direction);
+	else
+		fs = mnt_table_find_tag(tb, t, v, direction);
+
+	free(t);
+	free(v);
+
+	return fs;
+}
+
+/**
+ * mnt_table_find_pair
+ * @tb: tab pointer
+ * @source: TAG or path
+ * @target: mountpoint
+ * @direction: MNT_ITER_{FORWARD,BACKWARD}
+ *
+ * This function is implemented by mnt_fs_match_source() and
+ * mnt_fs_match_target() functions. It means that this is more expensive than
+ * others mnt_table_find_* function, because every @tab entry is fully evaluated.
+ *
+ * Returns: a tab entry or NULL.
+ */
+struct libmnt_fs *mnt_table_find_pair(struct libmnt_table *tb, const char *source,
+				      const char *target, int direction)
+{
+	struct libmnt_fs *fs = NULL;
+	struct libmnt_iter itr;
+
+	if (!tb || !target || !*target || !source || !*source)
+		return NULL;
+	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup SOURCE: %s TARGET: %s", source, target));
+
+	mnt_reset_iter(&itr, direction);
+	while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+
+		if (mnt_fs_match_target(fs, target, tb->cache) &&
+		    mnt_fs_match_source(fs, source, tb->cache))
+			return fs;
+	}
+
+	return NULL;
+}
+
+/**
+ * mnt_table_find_devno
+ * @tb: /proc/self/mountinfo
+ * @devno: device number
+ * @direction: MNT_ITER_{FORWARD,BACKWARD}
+ *
+ * Note that zero could be a valid device number for the root pseudo filesystem (e.g.
+ * tmpfs).
+ *
+ * Returns: a tab entry or NULL.
+ */
+struct libmnt_fs *mnt_table_find_devno(struct libmnt_table *tb,
+				       dev_t devno, int direction)
+{
+	struct libmnt_fs *fs = NULL;
+	struct libmnt_iter itr;
+
+	if (!tb)
+		return NULL;
+	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
+		return NULL;
+
+	DBG(TAB, ul_debugobj(tb, "lookup DEVNO: %d", (int) devno));
+
+	mnt_reset_iter(&itr, direction);
+
+	while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
+		if (mnt_fs_get_devno(fs) == devno)
+			return fs;
+	}
+
+	return NULL;
+}
+
+static char *remove_mountpoint_from_path(const char *path, const char *mnt)
+{
+        char *res;
+	const char *p;
+	size_t sz;
+
+	sz = strlen(mnt);
+	p = sz > 1 ? path + sz : path;
+
+	res = *p ? strdup(p) : strdup("/");
+	DBG(UTILS, ul_debug("%s fs-root is %s", path, res));
+	return res;
+}
+
+#ifdef HAVE_BTRFS_SUPPORT
+static int get_btrfs_fs_root(struct libmnt_table *tb, struct libmnt_fs *fs, char **root)
+{
+	char *vol = NULL, *p;
+	size_t sz, volsz = 0;
+
+	DBG(BTRFS, ul_debug("lookup for btrfs FS root"));
+	*root = NULL;
+
+	if (mnt_fs_get_option(fs, "subvolid", &vol, &volsz) == 0) {
+		char *target;
+		struct libmnt_fs *f;
+		char subvolidstr[sizeof(stringify_value(UINT64_MAX))];
+
+		DBG(BTRFS, ul_debug(" found subvolid=%s, checking", vol));
+
+		assert (volsz + 1 < sizeof(stringify_value(UINT64_MAX)));
+		memcpy(subvolidstr, vol, volsz);
+		subvolidstr[volsz] = '\0';
+
+		target = mnt_resolve_target(mnt_fs_get_target(fs), tb->cache);
+		if (!target)
+			goto err;
+
+		DBG(BTRFS, ul_debug(" trying target=%s subvolid=%s", target, subvolidstr));
+		f = mnt_table_find_target_with_option(tb, target,
+					"subvolid", subvolidstr,
+					MNT_ITER_BACKWARD);
+		if (!tb->cache)
+			free(target);
+		if (!f)
+			goto not_found;
+
+		/* Instead of set of BACKREF queries constructing subvol path
+		 * corresponding to a particular subvolid, use the one in
+		 * mountinfo. Kernel keeps subvol path up to date.
+		 */
+		if (mnt_fs_get_option(f, "subvol", &vol, &volsz) != 0)
+			goto not_found;
+
+	} else if (mnt_fs_get_option(fs, "subvol", &vol, &volsz) != 0) {
+		/* If fstab entry does not contain "subvol", we have to
+		 * check, whether btrfs has default subvolume defined.
+		 */
+		uint64_t default_id;
+		char *target;
+		struct libmnt_fs *f;
+		char default_id_str[sizeof(stringify_value(UINT64_MAX))];
+
+		DBG(BTRFS, ul_debug(" subvolid/subvol not found, checking default"));
+
+		default_id = btrfs_get_default_subvol_id(mnt_fs_get_target(fs));
+		if (default_id == UINT64_MAX)
+			goto not_found;
+
+		/* Volume has default subvolume. Check if it matches to
+		 * the one in mountinfo.
+		 *
+		 * Only kernel >= 4.2 reports subvolid. On older
+		 * kernels, there is no reasonable way to detect which
+		 * subvolume was mounted.
+		 */
+		target = mnt_resolve_target(mnt_fs_get_target(fs), tb->cache);
+		if (!target)
+			goto err;
+
+		snprintf(default_id_str, sizeof(default_id_str), "%llu",
+				(unsigned long long int) default_id);
+
+		DBG(BTRFS, ul_debug(" trying target=%s default subvolid=%s",
+					target, default_id_str));
+
+		f = mnt_table_find_target_with_option(tb, target,
+					"subvolid", default_id_str,
+					MNT_ITER_BACKWARD);
+		if (!tb->cache)
+			free(target);
+		if (!f)
+			goto not_found;
+
+		/* Instead of set of BACKREF queries constructing
+		 * subvol path, use the one in mountinfo. Kernel does
+		 * the evaluation for us.
+		 */
+		DBG(BTRFS, ul_debug("setting FS root: btrfs default subvolid = %s",
+					default_id_str));
+
+		if (mnt_fs_get_option(f, "subvol", &vol, &volsz) != 0)
+			goto not_found;
+	}
+
+	DBG(BTRFS, ul_debug(" using subvol=%s", vol));
+	sz = volsz;
+	if (*vol != '/')
+		sz++;
+	*root = malloc(sz + 1);
+	if (!*root)
+		goto err;
+	p = *root;
+	if (*vol != '/')
+		*p++ = '/';
+	memcpy(p, vol, volsz);
+	*(*root + sz) = '\0';
+	return 0;
+
+not_found:
+	DBG(BTRFS, ul_debug(" not found btrfs volume setting"));
+	return 1;
+err:
+	DBG(BTRFS, ul_debug(" error on btrfs volume setting evaluation"));
+	return errno ? -errno : -1;
+}
+#endif /* HAVE_BTRFS_SUPPORT */
+
+static const char *get_cifs_unc_subdir_path (const char *unc)
+{
+	/*
+	 *  1 or more slash:     %*[/]
+	 *  1 or more non-slash: %*[^/]
+	 *  number of byte read: %n
+	 */
+	int share_end = 0;
+	int r = sscanf(unc, "%*[/]%*[^/]%*[/]%*[^/]%n", &share_end);
+	if (r == EOF || share_end == 0)
+		return NULL;
+	return unc + share_end;
+}
+
+/*
+ * tb: /proc/self/mountinfo
+ * fs: filesystem
+ * mountflags: MS_BIND or 0
+ * fsroot: fs-root that will probably be used in the mountinfo file
+ *          for @fs after mount(2)
+ *
+ * For btrfs subvolumes this function returns NULL, but @fsroot properly set.
+ *
+ * If @tb is NULL then defaults to '/'.
+ *
+ * Returns: entry from @tb that will be used as a source for @fs if the @fs is
+ *          bindmount.
+ *
+ * Don't export to library API!
+ */
+struct libmnt_fs *mnt_table_get_fs_root(struct libmnt_table *tb,
+					struct libmnt_fs *fs,
+					unsigned long mountflags,
+					char **fsroot)
+{
+	char *root = NULL;
+	const char *mnt = NULL;
+	struct libmnt_fs *src_fs = NULL;
+
+	assert(fs);
+	assert(fsroot);
+
+	DBG(TAB, ul_debug("lookup fs-root for '%s'", mnt_fs_get_source(fs)));
+
+	if (tb && (mountflags & MS_BIND)) {
+		const char *src, *src_root;
+		char *xsrc = NULL;
+
+		DBG(TAB, ul_debug("fs-root for bind"));
+
+		src = xsrc = mnt_resolve_spec(mnt_fs_get_source(fs), tb->cache);
+		if (src) {
+			struct libmnt_fs *f = mnt_table_find_mountpoint(tb,
+							src, MNT_ITER_BACKWARD);
+			if (f)
+				mnt = mnt_fs_get_target(f);
+		}
+		if (mnt)
+			root = remove_mountpoint_from_path(src, mnt);
+
+		if (xsrc && !tb->cache) {
+			free(xsrc);
+			src = NULL;
+		}
+		if (!mnt)
+			goto err;
+
+		src_fs = mnt_table_find_target(tb, mnt, MNT_ITER_BACKWARD);
+		if (!src_fs)  {
+			DBG(TAB, ul_debug("not found '%s' in mountinfo -- using default", mnt));
+			goto dflt;
+		}
+
+		/* It's possible that fstab_fs source is subdirectory on btrfs
+		 * subvolume or another bind mount. For example:
+		 *
+		 * /dev/sdc        /mnt/test       btrfs   subvol=/anydir
+		 * /dev/sdc        /mnt/test       btrfs   defaults
+		 * /mnt/test/foo   /mnt/test2      auto    bind
+		 *
+		 * in this case, the root for /mnt/test2 will be /anydir/foo on
+		 * /dev/sdc. It means we have to compose the final root from
+		 * root and src_root.
+		 */
+		src_root = mnt_fs_get_root(src_fs);
+
+		DBG(FS, ul_debugobj(fs, "source root: %s, source FS root: %s", root, src_root));
+
+		if (src_root && !startswith(root, src_root)) {
+			if (strcmp(root, "/") == 0) {
+				free(root);
+				root = strdup(src_root);
+				if (!root)
+					goto err;
+			} else {
+				char *tmp;
+				if (asprintf(&tmp, "%s%s", src_root, root) < 0)
+					goto err;
+				free(root);
+				root = tmp;
+			}
+		}
+	}
+
+#ifdef HAVE_BTRFS_SUPPORT
+	/*
+	 * btrfs-subvolume mount -- get subvolume name and use it as a root-fs path
+	 */
+	else if (tb && fs->fstype &&
+		 (!strcmp(fs->fstype, "btrfs") || !strcmp(fs->fstype, "auto"))) {
+		if (get_btrfs_fs_root(tb, fs, &root) < 0)
+			goto err;
+	}
+#endif /* HAVE_BTRFS_SUPPORT */
+
+dflt:
+	if (!root) {
+		root = strdup("/");
+		if (!root)
+			goto err;
+	}
+	*fsroot = root;
+
+	DBG(TAB, ul_debug("FS root result: %s", root));
+
+	return src_fs;
+err:
+	free(root);
+	return NULL;
+}
+
+/**
+ * mnt_table_is_fs_mounted:
+ * @tb: /proc/self/mountinfo file
+ * @fstab_fs: /etc/fstab entry
+ *
+ * Checks if the @fstab_fs entry is already in the @tb table. The "swap" is
+ * ignored. This function explicitly compares the source, target and root of the
+ * filesystems.
+ *
+ * Note that source and target are canonicalized only if a cache for @tb is
+ * defined (see mnt_table_set_cache()). The target canonicalization may
+ * trigger automount on autofs mountpoints!
+ *
+ * Don't use it if you want to know if a device is mounted, just use
+ * mnt_table_find_source() on the device.
+ *
+ * This function is designed mostly for "mount -a".
+ *
+ * Returns: 0 or 1
+ */
+int mnt_table_is_fs_mounted(struct libmnt_table *tb, struct libmnt_fs *fstab_fs)
+{
+	struct libmnt_iter itr;
+	struct libmnt_fs *fs;
+
+	char *root = NULL;
+	char *src2 = NULL;
+	const char *src = NULL, *tgt = NULL;
+	char *xtgt = NULL;
+	int rc = 0;
+	dev_t devno = 0;
+
+	DBG(FS, ul_debugobj(fstab_fs, "mnt_table_is_fs_mounted: target=%s, source=%s",
+				mnt_fs_get_target(fstab_fs),
+				mnt_fs_get_source(fstab_fs)));
+
+	if (mnt_fs_is_swaparea(fstab_fs) || mnt_table_is_empty(tb)) {
+		DBG(FS, ul_debugobj(fstab_fs, "- ignore (swap or no data)"));
+		return 0;
+	}
+
+	if (is_mountinfo(tb)) {
+		/* @tb is mountinfo, so we can try to use fs-roots */
+		struct libmnt_fs *rootfs;
+		int flags = 0;
+
+		if (mnt_fs_get_option(fstab_fs, "bind", NULL, NULL) == 0 ||
+		    mnt_fs_get_option(fstab_fs, "rbind", NULL, NULL) == 0)
+			flags = MS_BIND;
+
+		rootfs = mnt_table_get_fs_root(tb, fstab_fs, flags, &root);
+		if (rootfs) {
+			const char *fstype = mnt_fs_get_fstype(rootfs);
+
+			src = mnt_fs_get_srcpath(rootfs);
+			if (fstype && strncmp(fstype, "nfs", 3) == 0 && root) {
+				/* NFS stores the root at the end of the source */
+				src = src2 = strappend(src, root);
+				free(root);
+				root = NULL;
+			}
+		}
+	}
+
+	if (!src)
+		src = mnt_fs_get_source(fstab_fs);
+
+	if (src && tb->cache && !mnt_fs_is_pseudofs(fstab_fs))
+		src = mnt_resolve_spec(src, tb->cache);
+
+	if (src && root) {
+		struct stat st;
+
+		devno = mnt_fs_get_devno(fstab_fs);
+		if (!devno && stat(src, &st) == 0 && S_ISBLK(st.st_mode))
+			devno = st.st_rdev;
+	}
+
+	tgt = mnt_fs_get_target(fstab_fs);
+
+	if (!tgt || !src) {
+		DBG(FS, ul_debugobj(fstab_fs, "- ignore (no source/target)"));
+		goto done;
+	}
+	mnt_reset_iter(&itr, MNT_ITER_FORWARD);
+
+	DBG(FS, ul_debugobj(fstab_fs, "mnt_table_is_fs_mounted: src=%s, tgt=%s, root=%s", src, tgt, root));
+
+	while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
+
+		int eq = mnt_fs_streq_srcpath(fs, src);
+
+		if (!eq && devno && mnt_fs_get_devno(fs) == devno)
+			eq = 1;
+
+		if (!eq) {
+			/* The source does not match. Maybe the source is a loop
+			 * device backing file.
+			 */
+			uint64_t offset = 0;
+			char *val;
+			size_t len;
+			int flags = 0;
+
+			if (!mnt_fs_get_srcpath(fs) ||
+			    !startswith(mnt_fs_get_srcpath(fs), "/dev/loop"))
+				continue;	/* does not look like loopdev */
+
+			if (mnt_fs_get_option(fstab_fs, "offset", &val, &len) == 0) {
+				if (mnt_parse_offset(val, len, &offset)) {
+					DBG(FS, ul_debugobj(fstab_fs, "failed to parse offset="));
+					continue;
+				}
+				flags = LOOPDEV_FL_OFFSET;
+			}
+
+			DBG(FS, ul_debugobj(fs, "checking for loop: src=%s", mnt_fs_get_srcpath(fs)));
+#if __linux__
+			if (!loopdev_is_used(mnt_fs_get_srcpath(fs), src, offset, 0, flags))
+				continue;
+
+			DBG(FS, ul_debugobj(fs, "used loop"));
+#endif
+		}
+
+		if (root) {
+			const char *fstype = mnt_fs_get_fstype(fs);
+
+			if (fstype && strcmp(fstype, "cifs") == 0) {
+				const char *unc_subdir = get_cifs_unc_subdir_path(src);
+				const char *path_on_fs = mnt_fs_get_root(fs);
+				if (!unc_subdir || !path_on_fs || !streq_paths(unc_subdir, path_on_fs))
+					continue;
+			} else {
+				const char *r = mnt_fs_get_root(fs);
+				if (!r || strcmp(r, root) != 0)
+					continue;
+			}
+		}
+
+		/*
+		 * Compare target, try to minimize the number of situations when we
+		 * need to canonicalize the path to avoid readlink() on
+		 * mountpoints.
+		 */
+		if (!xtgt) {
+			if (mnt_fs_streq_target(fs, tgt))
+				break;
+			if (tb->cache)
+				xtgt = mnt_resolve_path(tgt, tb->cache);
+		}
+		if (xtgt && mnt_fs_streq_target(fs, xtgt))
+			break;
+	}
+
+	if (fs)
+		rc = 1;		/* success */
+done:
+	free(root);
+
+	DBG(TAB, ul_debugobj(tb, "mnt_table_is_fs_mounted: %s [rc=%d]", src, rc));
+	free(src2);
+	return rc;
+}
+
+#ifdef TEST_PROGRAM
+#include "pathnames.h"
+
+static int parser_errcb(struct libmnt_table *tb, const char *filename, int line)
+{
+	fprintf(stderr, "%s:%d: parse error\n", filename, line);
+
+	return 1;	/* all errors are recoverable -- this is the default */
+}
+
+static struct libmnt_table *create_table(const char *file, int comments)
+{
+	struct libmnt_table *tb;
+
+	if (!file)
+		return NULL;
+	tb = mnt_new_table();
+	if (!tb)
+		goto err;
+
+	mnt_table_enable_comments(tb, comments);
+	mnt_table_set_parser_errcb(tb, parser_errcb);
+
+	if (mnt_table_parse_file(tb, file) != 0)
+		goto err;
+	return tb;
+err:
+	fprintf(stderr, "%s: parsing failed\n", file);
+	mnt_unref_table(tb);
+	return NULL;
+}
+
+static int test_copy_fs(struct libmnt_test *ts, int argc, char *argv[])
+{
+	struct libmnt_table *tb;
+	struct libmnt_fs *fs;
+	int rc = -1;
+
+	tb = create_table(argv[1], FALSE);
+	if (!tb)
+		return -1;
+
+	fs = mnt_table_find_target(tb, "/", MNT_ITER_FORWARD);
+	if (!fs)
+		goto done;
+
+	printf("ORIGINAL:\n");
+	mnt_fs_print_debug(fs, stdout);
+
+	fs = mnt_copy_fs(NULL, fs);
+	if (!fs)
+		goto done;
+
+	printf("COPY:\n");
+	mnt_fs_print_debug(fs, stdout);
+	mnt_unref_fs(fs);
+	rc = 0;
+done:
+	mnt_unref_table(tb);
+	return rc;
+}
+
+static int test_parse(struct libmnt_test *ts, int argc, char *argv[])
+{
+	struct libmnt_table *tb = NULL;
+	struct libmnt_iter *itr = NULL;
+	struct libmnt_fs *fs;
+	int rc = -1;
+	int parse_comments = FALSE;
+
+	if (argc == 3 && !strcmp(argv[2], "--comments"))
+		parse_comments = TRUE;
+
+	tb = create_table(argv[1], parse_comments);
+	if (!tb)
+		return -1;
+
+	itr = mnt_new_iter(MNT_ITER_FORWARD);
+	if (!itr)
+		goto done;
+
+	if (mnt_table_get_intro_comment(tb))
+		fprintf(stdout, "Initial comment:\n\"%s\"\n",
+				mnt_table_get_intro_comment(tb));
+
+	while(mnt_table_next_fs(tb, itr, &fs) == 0)
+		mnt_fs_print_debug(fs, stdout);
+
+	if (mnt_table_get_trailing_comment(tb))
+		fprintf(stdout, "Trailing comment:\n\"%s\"\n",
+				mnt_table_get_trailing_comment(tb));
+	rc = 0;
+done:
+	mnt_free_iter(itr);
+	mnt_unref_table(tb);
+	return rc;
+}
+
+static int test_find(struct libmnt_test *ts, int argc, char *argv[], int dr)
+{
+	struct libmnt_table *tb;
+	struct libmnt_fs *fs = NULL;
+	struct libmnt_cache *mpc = NULL;
+	const char *file, *find, *what;
+	int rc = -1;
+
+	if (argc != 4) {
+		fprintf(stderr, "try --help\n");
+		return -EINVAL;
+	}
+
+	file = argv[1], find = argv[2], what = argv[3];
+
+	tb = create_table(file, FALSE);
+	if (!tb)
+		goto done;
+
+	/* create a cache for canonicalized paths */
+	mpc = mnt_new_cache();
+	if (!mpc)
+		goto done;
+	mnt_table_set_cache(tb, mpc);
+	mnt_unref_cache(mpc);
+
+	if (strcasecmp(find, "source") == 0)
+		fs = mnt_table_find_source(tb, what, dr);
+	else if (strcasecmp(find, "target") == 0)
+		fs = mnt_table_find_target(tb, what, dr);
+
+	if (!fs)
+		fprintf(stderr, "%s: not found %s '%s'\n", file, find, what);
+	else {
+		mnt_fs_print_debug(fs, stdout);
+		rc = 0;
+	}
+done:
+	mnt_unref_table(tb);
+	return rc;
+}
+
+static int test_find_bw(struct libmnt_test *ts, int argc, char *argv[])
+{
+	return test_find(ts, argc, argv, MNT_ITER_BACKWARD);
+}
+
+static int test_find_fw(struct libmnt_test *ts, int argc, char *argv[])
+{
+	return test_find(ts, argc, argv, MNT_ITER_FORWARD);
+}
+
+static int test_find_pair(struct libmnt_test *ts, int argc, char *argv[])
+{
+	struct libmnt_table *tb;
+	struct libmnt_fs *fs;
+	struct libmnt_cache *mpc = NULL;
+	int rc = -1;
+
+	tb = create_table(argv[1], FALSE);
+	if (!tb)
+		return -1;
+	mpc = mnt_new_cache();
+	if (!mpc)
+		goto done;
+	mnt_table_set_cache(tb, mpc);
+	mnt_unref_cache(mpc);
+
+	fs = mnt_table_find_pair(tb, argv[2], argv[3], MNT_ITER_FORWARD);
+	if (!fs)
+		goto done;
+
+	mnt_fs_print_debug(fs, stdout);
+	rc = 0;
+done:
+	mnt_unref_table(tb);
+	return rc;
+}
+
+static int test_find_mountpoint(struct libmnt_test *ts, int argc, char *argv[])
+{
+	struct libmnt_table *tb;
+	struct libmnt_fs *fs;
+	struct libmnt_cache *mpc = NULL;
+	int rc = -1;
+
+	tb = mnt_new_table_from_file(_PATH_PROC_MOUNTINFO);
+	if (!tb)
+		return -1;
+	mpc = mnt_new_cache();
+	if (!mpc)
+		goto done;
+	mnt_table_set_cache(tb, mpc);
+	mnt_unref_cache(mpc);
+
+	fs = mnt_table_find_mountpoint(tb, argv[1], MNT_ITER_BACKWARD);
+	if (!fs)
+		goto done;
+
+	mnt_fs_print_debug(fs, stdout);
+	rc = 0;
+done:
+	mnt_unref_table(tb);
+	return rc;
+}
+
+static int test_is_mounted(struct libmnt_test *ts, int argc, char *argv[])
+{
+	struct libmnt_table *tb = NULL, *fstab = NULL;
+	struct libmnt_fs *fs;
+	struct libmnt_iter *itr = NULL;
+	struct libmnt_cache *mpc = NULL;
+	int writable = 0;
+	const char *path = NULL;
+
+	if (mnt_has_regular_mtab(&path, &writable) == 1 && writable == 0)
+		tb = mnt_new_table_from_file(path);
+	else
+		tb = mnt_new_table_from_file("/proc/self/mountinfo");
+
+	if (!tb) {
+		fprintf(stderr, "failed to parse mountinfo\n");
+		return -1;
+	}
+
+	fstab = create_table(argv[1], FALSE);
+	if (!fstab)
+		goto done;
+
+	itr = mnt_new_iter(MNT_ITER_FORWARD);
+	if (!itr)
+		goto done;
+
+	mpc = mnt_new_cache();
+	if (!mpc)
+		goto done;
+	mnt_table_set_cache(tb, mpc);
+	mnt_unref_cache(mpc);
+
+	while (mnt_table_next_fs(fstab, itr, &fs) == 0) {
+		if (mnt_table_is_fs_mounted(tb, fs))
+			printf("%s already mounted on %s\n",
+					mnt_fs_get_source(fs),
+					mnt_fs_get_target(fs));
+		else
+			printf("%s not mounted on %s\n",
+					mnt_fs_get_source(fs),
+					mnt_fs_get_target(fs));
+	}
+
+done:
+	mnt_unref_table(tb);
+	mnt_unref_table(fstab);
+	mnt_free_iter(itr);
+	return 0;
+}
+
+/* returns 0 if @a and @b targets are the same */
+static int test_uniq_cmp(struct libmnt_table *tb __attribute__((__unused__)),
+			 struct libmnt_fs *a,
+			 struct libmnt_fs *b)
+{
+	assert(a);
+	assert(b);
+
+	return mnt_fs_streq_target(a, mnt_fs_get_target(b)) ? 0 : 1;
+}
+
+static int test_uniq(struct libmnt_test *ts, int argc, char *argv[])
+{
+	struct libmnt_table *tb;
+	int rc = -1;
+
+	if (argc != 2) {
+		fprintf(stderr, "try --help\n");
+		return -EINVAL;
+	}
+
+	tb = create_table(argv[1], FALSE);
+	if (!tb)
+		goto done;
+
+	if (mnt_table_uniq_fs(tb, 0, test_uniq_cmp) == 0) {
+		struct libmnt_iter *itr = mnt_new_iter(MNT_ITER_FORWARD);
+		struct libmnt_fs *fs;
+		if (!itr)
+			goto done;
+		while (mnt_table_next_fs(tb, itr, &fs) == 0)
+			mnt_fs_print_debug(fs, stdout);
+		mnt_free_iter(itr);
+		rc = 0;
+	}
+done:
+	mnt_unref_table(tb);
+	return rc;
+}
+
+
+int main(int argc, char *argv[])
+{
+	struct libmnt_test tss[] = {
+	{ "--parse",    test_parse,        "<file> [--comments] parse and print tab" },
+	{ "--find-forward",  test_find_fw, "<file> <source|target> <string>" },
+	{ "--find-backward", test_find_bw, "<file> <source|target> <string>" },
+	{ "--uniq-target",   test_uniq,    "<file>" },
+	{ "--find-pair",     test_find_pair, "<file> <source> <target>" },
+	{ "--find-mountpoint", test_find_mountpoint, "<path>" },
+	{ "--copy-fs",       test_copy_fs, "<file>  copy root FS from the file" },
+	{ "--is-mounted",    test_is_mounted, "<fstab> check what from fstab is already mounted" },
+	{ NULL }
+	};
+
+	return mnt_run_test(tss, argc, argv);
+}
+
+#endif /* TEST_PROGRAM */