Adding upstream version 2.36.1.upstream/2.36.1upstream

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

1 files changed, 1524 insertions, 0 deletions

diff --git a/libmount/src/utils.c b/libmount/src/utils.c
new file mode 100644
index 0000000..92829eb
--- /dev/null
+++ b/libmount/src/utils.c
@@ -0,0 +1,1524 @@
+/* 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: utils
+ * @title: Utils
+ * @short_description: misc utils.
+ */
+#include <ctype.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <grp.h>
+#include <poll.h>
+#include <blkid.h>
+
+#include "strutils.h"
+#include "pathnames.h"
+#include "mountP.h"
+#include "mangle.h"
+#include "canonicalize.h"
+#include "env.h"
+#include "match.h"
+#include "fileutils.h"
+#include "statfs_magic.h"
+#include "sysfs.h"
+
+int append_string(char **a, const char *b)
+{
+	size_t al, bl;
+	char *tmp;
+
+	assert(a);
+
+	if (!b || !*b)
+		return 0;
+	if (!*a) {
+		*a = strdup(b);
+		return !*a ? -ENOMEM : 0;
+	}
+
+	al = strlen(*a);
+	bl = strlen(b);
+
+	tmp = realloc(*a, al + bl + 1);
+	if (!tmp)
+		return -ENOMEM;
+	*a = tmp;
+	memcpy((*a) + al, b, bl + 1);
+	return 0;
+}
+
+/*
+ * Return 1 if the file is not accessible or empty
+ */
+int is_file_empty(const char *name)
+{
+	struct stat st;
+	assert(name);
+
+	return (stat(name, &st) != 0 || st.st_size == 0);
+}
+
+int mnt_valid_tagname(const char *tagname)
+{
+	if (tagname && *tagname && (
+	    strcmp("ID", tagname) == 0 ||
+	    strcmp("UUID", tagname) == 0 ||
+	    strcmp("LABEL", tagname) == 0 ||
+	    strcmp("PARTUUID", tagname) == 0 ||
+	    strcmp("PARTLABEL", tagname) == 0))
+		return 1;
+
+	return 0;
+}
+
+/**
+ * mnt_tag_is_valid:
+ * @tag: NAME=value string
+ *
+ * Returns: 1 if the @tag is parsable and tag NAME= is supported by libmount, or 0.
+ */
+int mnt_tag_is_valid(const char *tag)
+{
+	char *t = NULL;
+	int rc = tag && blkid_parse_tag_string(tag, &t, NULL) == 0
+		     && mnt_valid_tagname(t);
+
+	free(t);
+	return rc;
+}
+
+int mnt_parse_offset(const char *str, size_t len, uintmax_t *res)
+{
+	char *p;
+	int rc = 0;
+
+	if (!str || !*str)
+		return -EINVAL;
+
+	p = strndup(str, len);
+	if (!p)
+		return -errno;
+
+	if (strtosize(p, res))
+		rc = -EINVAL;
+	free(p);
+	return rc;
+}
+
+/* used as a callback by bsearch in mnt_fstype_is_pseudofs() */
+static int fstype_cmp(const void *v1, const void *v2)
+{
+	const char *s1 = *(char * const *)v1;
+	const char *s2 = *(char * const *)v2;
+
+	return strcmp(s1, s2);
+}
+
+int mnt_stat_mountpoint(const char *target, struct stat *st)
+{
+#ifdef AT_NO_AUTOMOUNT
+	return fstatat(AT_FDCWD, target, st, AT_NO_AUTOMOUNT);
+#else
+	return stat(target, st);
+#endif
+}
+
+int mnt_lstat_mountpoint(const char *target, struct stat *st)
+{
+#ifdef AT_NO_AUTOMOUNT
+	return fstatat(AT_FDCWD, target, st, AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW);
+#else
+	return lstat(target, st);
+#endif
+}
+
+
+/*
+ * Note that the @target has to be an absolute path (so at least "/").  The
+ * @filename returns an allocated buffer with the last path component, for example:
+ *
+ * mnt_chdir_to_parent("/mnt/test", &buf) ==> chdir("/mnt"), buf="test"
+ */
+int mnt_chdir_to_parent(const char *target, char **filename)
+{
+	char *buf, *parent, *last = NULL;
+	char cwd[PATH_MAX];
+	int rc = -EINVAL;
+
+	if (!target || *target != '/')
+		return -EINVAL;
+
+	DBG(UTILS, ul_debug("moving to %s parent", target));
+
+	buf = strdup(target);
+	if (!buf)
+		return -ENOMEM;
+
+	if (*(buf + 1) != '\0') {
+		last = stripoff_last_component(buf);
+		if (!last)
+			goto err;
+	}
+
+	parent = buf && *buf ? buf : "/";
+
+	if (chdir(parent) == -1) {
+		DBG(UTILS, ul_debug("failed to chdir to %s: %m", parent));
+		rc = -errno;
+		goto err;
+	}
+	if (!getcwd(cwd, sizeof(cwd))) {
+		DBG(UTILS, ul_debug("failed to obtain current directory: %m"));
+		rc = -errno;
+		goto err;
+	}
+	if (strcmp(cwd, parent) != 0) {
+		DBG(UTILS, ul_debug(
+		    "unexpected chdir (expected=%s, cwd=%s)", parent, cwd));
+		goto err;
+	}
+
+	DBG(CXT, ul_debug(
+		"current directory moved to %s [last_component='%s']",
+		parent, last));
+
+	if (filename) {
+		*filename = buf;
+
+		if (!last || !*last)
+			memcpy(*filename, ".", 2);
+		else
+			memmove(*filename, last, strlen(last) + 1);
+	} else
+		free(buf);
+	return 0;
+err:
+	free(buf);
+	return rc;
+}
+
+/*
+ * Check if @path is on a read-only filesystem independently of file permissions.
+ */
+int mnt_is_readonly(const char *path)
+{
+	if (access(path, W_OK) == 0)
+		return 0;
+	if (errno == EROFS)
+		return 1;
+	if (errno != EACCES)
+		return 0;
+
+#ifdef HAVE_UTIMENSAT
+	/*
+	 * access(2) returns EACCES on read-only FS:
+	 *
+	 * - for set-uid application if one component of the path is not
+	 *   accessible for the current rUID. (Note that euidaccess(2) does not
+	 *   check for EROFS at all).
+	 *
+	 * - for a read-write filesystem with a read-only VFS node (aka -o remount,ro,bind)
+	 */
+	{
+		struct timespec times[2];
+
+		DBG(UTILS, ul_debug(" doing utimensat() based write test"));
+
+		times[0].tv_nsec = UTIME_NOW;	/* atime */
+		times[1].tv_nsec = UTIME_OMIT;	/* mtime */
+
+		if (utimensat(AT_FDCWD, path, times, 0) == -1)
+			return errno == EROFS;
+	}
+#endif
+	return 0;
+}
+
+/**
+ * mnt_mangle:
+ * @str: string
+ *
+ * Encode @str to be compatible with fstab/mtab
+ *
+ * Returns: newly allocated string or NULL in case of error.
+ */
+char *mnt_mangle(const char *str)
+{
+	return mangle(str);
+}
+
+/**
+ * mnt_unmangle:
+ * @str: string
+ *
+ * Decode @str from fstab/mtab
+ *
+ * Returns: newly allocated string or NULL in case of error.
+ */
+char *mnt_unmangle(const char *str)
+{
+	return unmangle(str, NULL);
+}
+
+/**
+ * mnt_fstype_is_pseudofs:
+ * @type: filesystem name
+ *
+ * Returns: 1 for filesystems like proc, sysfs, ... or 0.
+ */
+int mnt_fstype_is_pseudofs(const char *type)
+{
+	/* This array must remain sorted when adding new fstypes */
+	static const char *pseudofs[] = {
+		"anon_inodefs",
+		"apparmorfs",
+		"autofs",
+		"bdev",
+		"binder",
+		"binfmt_misc",
+		"bpf",
+		"cgroup",
+		"cgroup2",
+		"configfs",
+		"cpuset",
+		"debugfs",
+		"devfs",
+		"devpts",
+		"devtmpfs",
+		"dlmfs",
+		"dmabuf",
+		"drm",
+		"efivarfs",
+		"fuse", /* Fallback name of fuse used by many poorly written drivers. */
+		"fuse.archivemount", /* Not a true pseudofs (has source), but source is not reported. */
+		"fuse.avfsd", /* Not a true pseudofs (has source), but source is not reported. */
+		"fuse.dumpfs", /* In fact, it is a netfs, but source is not reported. */
+		"fuse.encfs", /* Not a true pseudofs (has source), but source is not reported. */
+		"fuse.gvfs-fuse-daemon", /* Old name, not used by gvfs any more. */
+		"fuse.gvfsd-fuse",
+		"fuse.lxcfs",
+		"fuse.rofiles-fuse",
+		"fuse.vmware-vmblock",
+		"fuse.xwmfs",
+		"fusectl",
+		"hugetlbfs",
+		"ipathfs",
+		"mqueue",
+		"nfsd",
+		"none",
+		"nsfs",
+		"overlay",
+		"pipefs",
+		"proc",
+		"pstore",
+		"ramfs",
+		"resctrl",
+		"rootfs",
+		"rpc_pipefs",
+		"securityfs",
+		"selinuxfs",
+		"smackfs",
+		"sockfs",
+		"spufs",
+		"sysfs",
+		"tmpfs",
+		"tracefs"
+	};
+
+	assert(type);
+
+	return !(bsearch(&type, pseudofs, ARRAY_SIZE(pseudofs),
+				sizeof(char*), fstype_cmp) == NULL);
+}
+
+/**
+ * mnt_fstype_is_netfs:
+ * @type: filesystem name
+ *
+ * Returns: 1 for filesystems like cifs, nfs, ... or 0.
+ */
+int mnt_fstype_is_netfs(const char *type)
+{
+	if (strcmp(type, "cifs")   == 0 ||
+	    strcmp(type, "smb3")   == 0 ||
+	    strcmp(type, "smbfs")  == 0 ||
+	    strncmp(type,"nfs", 3) == 0 ||
+	    strcmp(type, "afs")    == 0 ||
+	    strcmp(type, "ncpfs")  == 0 ||
+	    strcmp(type, "fuse.curlftpfs") == 0 ||
+	    strcmp(type, "fuse.sshfs") == 0 ||
+	    strncmp(type,"9p", 2)  == 0)
+		return 1;
+	return 0;
+}
+
+const char *mnt_statfs_get_fstype(struct statfs *vfs)
+{
+	assert(vfs);
+
+	switch (vfs->f_type) {
+	case STATFS_ADFS_MAGIC:		return "adfs";
+	case STATFS_AFFS_MAGIC:		return "affs";
+	case STATFS_AFS_MAGIC:		return "afs";
+	case STATFS_AUTOFS_MAGIC:	return "autofs";
+	case STATFS_BDEVFS_MAGIC:	return "bdev";
+	case STATFS_BEFS_MAGIC:		return "befs";
+	case STATFS_BFS_MAGIC:		return "befs";
+	case STATFS_BINFMTFS_MAGIC:	return "binfmt_misc";
+	case STATFS_BTRFS_MAGIC:	return "btrfs";
+	case STATFS_CEPH_MAGIC:		return "ceph";
+	case STATFS_CGROUP_MAGIC:	return "cgroup";
+	case STATFS_CIFS_MAGIC:		return "cifs";
+	case STATFS_CODA_MAGIC:		return "coda";
+	case STATFS_CONFIGFS_MAGIC:	return "configfs";
+	case STATFS_CRAMFS_MAGIC:	return "cramfs";
+	case STATFS_DEBUGFS_MAGIC:	return "debugfs";
+	case STATFS_DEVPTS_MAGIC:	return "devpts";
+	case STATFS_ECRYPTFS_MAGIC:	return "ecryptfs";
+	case STATFS_EFIVARFS_MAGIC:	return "efivarfs";
+	case STATFS_EFS_MAGIC:		return "efs";
+	case STATFS_EXOFS_MAGIC:	return "exofs";
+	case STATFS_EXT4_MAGIC:		return "ext4";	   /* all extN use the same magic */
+	case STATFS_F2FS_MAGIC:		return "f2fs";
+	case STATFS_FUSE_MAGIC:		return "fuse";
+	case STATFS_FUTEXFS_MAGIC:	return "futexfs";
+	case STATFS_GFS2_MAGIC:		return "gfs2";
+	case STATFS_HFSPLUS_MAGIC:	return "hfsplus";
+	case STATFS_HOSTFS_MAGIC:	return "hostfs";
+	case STATFS_HPFS_MAGIC:		return "hpfs";
+	case STATFS_HPPFS_MAGIC:	return "hppfs";
+	case STATFS_HUGETLBFS_MAGIC:	return "hugetlbfs";
+	case STATFS_ISOFS_MAGIC:	return "iso9660";
+	case STATFS_JFFS2_MAGIC:	return "jffs2";
+	case STATFS_JFS_MAGIC:		return "jfs";
+	case STATFS_LOGFS_MAGIC:	return "logfs";
+	case STATFS_MINIX2_MAGIC:
+	case STATFS_MINIX2_MAGIC2:
+	case STATFS_MINIX3_MAGIC:
+	case STATFS_MINIX_MAGIC:
+	case STATFS_MINIX_MAGIC2:	return "minix";
+	case STATFS_MQUEUE_MAGIC:	return "mqueue";
+	case STATFS_MSDOS_MAGIC:	return "vfat";
+	case STATFS_NCP_MAGIC:		return "ncp";
+	case STATFS_NFS_MAGIC:		return "nfs";
+	case STATFS_NILFS_MAGIC:	return "nilfs2";
+	case STATFS_NTFS_MAGIC:		return "ntfs";
+	case STATFS_OCFS2_MAGIC:	return "ocfs2";
+	case STATFS_OMFS_MAGIC:		return "omfs";
+	case STATFS_OPENPROMFS_MAGIC:	return "openpromfs";
+	case STATFS_PIPEFS_MAGIC:	return "pipefs";
+	case STATFS_PROC_MAGIC:		return "proc";
+	case STATFS_PSTOREFS_MAGIC:	return "pstore";
+	case STATFS_QNX4_MAGIC:		return "qnx4";
+	case STATFS_QNX6_MAGIC:		return "qnx6";
+	case STATFS_RAMFS_MAGIC:	return "ramfs";
+	case STATFS_REISERFS_MAGIC:	return "reiser4";
+	case STATFS_ROMFS_MAGIC:	return "romfs";
+	case STATFS_SECURITYFS_MAGIC:	return "securityfs";
+	case STATFS_SELINUXFS_MAGIC:	return "selinuxfs";
+	case STATFS_SMACKFS_MAGIC:	return "smackfs";
+	case STATFS_SMB_MAGIC:		return "smb";
+	case STATFS_SOCKFS_MAGIC:	return "sockfs";
+	case STATFS_SQUASHFS_MAGIC:	return "squashfs";
+	case STATFS_SYSFS_MAGIC:	return "sysfs";
+	case STATFS_TMPFS_MAGIC:	return "tmpfs";
+	case STATFS_UBIFS_MAGIC:	return "ubifs";
+	case STATFS_UDF_MAGIC:		return "udf";
+	case STATFS_UFS2_MAGIC:
+	case STATFS_UFS_MAGIC:		return "ufs";
+	case STATFS_V9FS_MAGIC:		return "9p";
+	case STATFS_VXFS_MAGIC:		return "vxfs";
+	case STATFS_XENFS_MAGIC:	return "xenfs";
+	case STATFS_XFS_MAGIC:		return "xfs";
+	default:
+		break;
+	}
+
+	return NULL;
+}
+
+int is_procfs_fd(int fd)
+{
+	struct statfs sfs;
+
+	return fstatfs(fd, &sfs) == 0 && sfs.f_type == STATFS_PROC_MAGIC;
+}
+
+/**
+ * mnt_match_fstype:
+ * @type: filesystem type
+ * @pattern: filesystem name or comma delimited list of names
+ *
+ * The @pattern list of filesystems can be prefixed with a global
+ * "no" prefix to invert matching of the whole list. The "no" could
+ * also be used for individual items in the @pattern list. So,
+ * "nofoo,bar" has the same meaning as "nofoo,nobar".
+ *
+ * "bar"  : "nofoo,bar"		-> False   (global "no" prefix)
+ *
+ * "bar"  : "foo,bar"		-> True
+ *
+ * "bar" : "foo,nobar"		-> False
+ *
+ * Returns: 1 if type is matching, else 0. This function also returns
+ *          0 if @pattern is NULL and @type is non-NULL.
+ */
+int mnt_match_fstype(const char *type, const char *pattern)
+{
+	return match_fstype(type, pattern);
+}
+
+void mnt_free_filesystems(char **filesystems)
+{
+	char **p;
+
+	if (!filesystems)
+		return;
+	for (p = filesystems; *p; p++)
+		free(*p);
+	free(filesystems);
+}
+
+static int add_filesystem(char ***filesystems, char *name)
+{
+	int n = 0;
+
+	assert(filesystems);
+	assert(name);
+
+	if (*filesystems) {
+		char **p;
+		for (n = 0, p = *filesystems; *p; p++, n++) {
+			if (strcmp(*p, name) == 0)
+				return 0;
+		}
+	}
+
+	#define MYCHUNK	16
+
+	if (n == 0 || !((n + 1) % MYCHUNK)) {
+		size_t items = ((n + 1 + MYCHUNK) / MYCHUNK) * MYCHUNK;
+		char **x = realloc(*filesystems, items * sizeof(char *));
+
+		if (!x)
+			goto err;
+		*filesystems = x;
+	}
+	name = strdup(name);
+	(*filesystems)[n] = name;
+	(*filesystems)[n + 1] = NULL;
+	if (!name)
+		goto err;
+	return 0;
+err:
+	mnt_free_filesystems(*filesystems);
+	return -ENOMEM;
+}
+
+static int get_filesystems(const char *filename, char ***filesystems, const char *pattern)
+{
+	int rc = 0;
+	FILE *f;
+	char line[129];
+
+	f = fopen(filename, "r" UL_CLOEXECSTR);
+	if (!f)
+		return 1;
+
+	DBG(UTILS, ul_debug("reading filesystems list from: %s", filename));
+
+	while (fgets(line, sizeof(line), f)) {
+		char name[sizeof(line)];
+
+		if (*line == '#' || strncmp(line, "nodev", 5) == 0)
+			continue;
+		if (sscanf(line, " %128[^\n ]\n", name) != 1)
+			continue;
+		if (strcmp(name, "*") == 0) {
+			rc = 1;
+			break;		/* end of the /etc/filesystems */
+		}
+		if (pattern && !mnt_match_fstype(name, pattern))
+			continue;
+		rc = add_filesystem(filesystems, name);
+		if (rc)
+			break;
+	}
+
+	fclose(f);
+	return rc;
+}
+
+/*
+ * Always check the @filesystems pointer!
+ *
+ * man mount:
+ *
+ * ...mount will try to read the file /etc/filesystems, or, if that does not
+ * exist, /proc/filesystems. All of the filesystem  types  listed  there  will
+ * be tried,  except  for  those  that  are  labeled  "nodev"  (e.g.,  devpts,
+ * proc  and  nfs).  If /etc/filesystems ends in a line with a single * only,
+ * mount will read /proc/filesystems afterwards.
+ */
+int mnt_get_filesystems(char ***filesystems, const char *pattern)
+{
+	int rc;
+
+	if (!filesystems)
+		return -EINVAL;
+
+	*filesystems = NULL;
+
+	rc = get_filesystems(_PATH_FILESYSTEMS, filesystems, pattern);
+	if (rc != 1)
+		return rc;
+
+	rc = get_filesystems(_PATH_PROC_FILESYSTEMS, filesystems, pattern);
+	if (rc == 1 && *filesystems)
+		rc = 0;			/* /proc/filesystems not found */
+
+	return rc;
+}
+
+/*
+ * Returns an allocated string with username or NULL.
+ */
+char *mnt_get_username(const uid_t uid)
+{
+        struct passwd pwd;
+	struct passwd *res;
+	char *buf, *username = NULL;
+
+	buf = malloc(UL_GETPW_BUFSIZ);
+	if (!buf)
+		return NULL;
+
+	if (!getpwuid_r(uid, &pwd, buf, UL_GETPW_BUFSIZ, &res) && res)
+		username = strdup(pwd.pw_name);
+
+	free(buf);
+	return username;
+}
+
+int mnt_get_uid(const char *username, uid_t *uid)
+{
+	int rc = -1;
+        struct passwd pwd;
+	struct passwd *pw;
+	char *buf;
+
+	if (!username || !uid)
+		return -EINVAL;
+
+	buf = malloc(UL_GETPW_BUFSIZ);
+	if (!buf)
+		return -ENOMEM;
+
+	if (!getpwnam_r(username, &pwd, buf, UL_GETPW_BUFSIZ, &pw) && pw) {
+		*uid= pw->pw_uid;
+		rc = 0;
+	} else {
+		DBG(UTILS, ul_debug(
+			"cannot convert '%s' username to UID", username));
+		rc = errno ? -errno : -EINVAL;
+	}
+
+	free(buf);
+	return rc;
+}
+
+int mnt_get_gid(const char *groupname, gid_t *gid)
+{
+	int rc = -1;
+        struct group grp;
+	struct group *gr;
+	char *buf;
+
+	if (!groupname || !gid)
+		return -EINVAL;
+
+	buf = malloc(UL_GETPW_BUFSIZ);
+	if (!buf)
+		return -ENOMEM;
+
+	if (!getgrnam_r(groupname, &grp, buf, UL_GETPW_BUFSIZ, &gr) && gr) {
+		*gid= gr->gr_gid;
+		rc = 0;
+	} else {
+		DBG(UTILS, ul_debug(
+			"cannot convert '%s' groupname to GID", groupname));
+		rc = errno ? -errno : -EINVAL;
+	}
+
+	free(buf);
+	return rc;
+}
+
+int mnt_in_group(gid_t gid)
+{
+	int rc = 0, n, i;
+	gid_t *grps = NULL;
+
+	if (getgid() == gid)
+		return 1;
+
+	n = getgroups(0, NULL);
+	if (n <= 0)
+		goto done;
+
+	grps = malloc(n * sizeof(*grps));
+	if (!grps)
+		goto done;
+
+	if (getgroups(n, grps) == n) {
+		for (i = 0; i < n; i++) {
+			if (grps[i] == gid) {
+				rc = 1;
+				break;
+			}
+		}
+	}
+done:
+	free(grps);
+	return rc;
+}
+
+static int try_write(const char *filename, const char *directory)
+{
+	int rc = 0;
+
+	if (!filename)
+		return -EINVAL;
+
+	DBG(UTILS, ul_debug("try write %s dir: %s", filename, directory));
+
+#ifdef HAVE_EACCESS
+	/* Try eaccess() first, because open() is overkill, may be monitored by
+	 * audit and we don't want to fill logs by our checks...
+	 */
+	if (eaccess(filename, R_OK|W_OK) == 0) {
+		DBG(UTILS, ul_debug(" access OK"));
+		return 0;
+	}
+
+	if (errno != ENOENT) {
+		DBG(UTILS, ul_debug(" access FAILED"));
+		return -errno;
+	}
+
+	if (directory) {
+		/* file does not exist; try if directory is writable */
+		if (eaccess(directory, R_OK|W_OK) != 0)
+			rc = -errno;
+
+		DBG(UTILS, ul_debug(" access %s [%s]", rc ? "FAILED" : "OK", directory));
+		return rc;
+	}
+#endif
+
+	DBG(UTILS, ul_debug(" doing open-write test"));
+
+	int fd = open(filename, O_RDWR|O_CREAT|O_CLOEXEC,
+		    S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH);
+	if (fd < 0)
+		rc = -errno;
+	else
+		close(fd);
+
+	return rc;
+}
+
+/**
+ * mnt_has_regular_mtab:
+ * @mtab: returns path to mtab
+ * @writable: returns 1 if the file is writable
+ *
+ * If the file does not exist and @writable argument is not NULL, then it will
+ * try to create the file.
+ *
+ * Returns: 1 if /etc/mtab is a regular file, and 0 in case of error (check
+ *          errno for more details).
+ */
+int mnt_has_regular_mtab(const char **mtab, int *writable)
+{
+	struct stat st;
+	int rc;
+	const char *filename = mtab && *mtab ? *mtab : mnt_get_mtab_path();
+
+	if (writable)
+		*writable = 0;
+	if (mtab && !*mtab)
+		*mtab = filename;
+
+	DBG(UTILS, ul_debug("mtab: %s", filename));
+
+	rc = lstat(filename, &st);
+
+	if (rc == 0) {
+		/* file exists */
+		if (S_ISREG(st.st_mode)) {
+			if (writable)
+				*writable = !try_write(filename, NULL);
+			DBG(UTILS, ul_debug("%s: writable", filename));
+			return 1;
+		}
+		goto done;
+	}
+
+	/* try to create the file */
+	if (writable) {
+		*writable = !try_write(filename, NULL);
+		if (*writable) {
+			DBG(UTILS, ul_debug("%s: writable", filename));
+			return 1;
+		}
+	}
+
+done:
+	DBG(UTILS, ul_debug("%s: irregular/non-writable", filename));
+	return 0;
+}
+
+/*
+ * Don't export this to libmount API -- utab is private library stuff.
+ *
+ * If the file does not exist and @writable argument is not NULL, then it will
+ * try to create the directory (e.g. /run/mount) and the file.
+ *
+ * Returns: 1 if utab is a regular file, and 0 in case of
+ *          error (check errno for more details).
+ */
+int mnt_has_regular_utab(const char **utab, int *writable)
+{
+	struct stat st;
+	int rc;
+	const char *filename = utab && *utab ? *utab : mnt_get_utab_path();
+
+	if (writable)
+		*writable = 0;
+	if (utab && !*utab)
+		*utab = filename;
+
+	DBG(UTILS, ul_debug("utab: %s", filename));
+
+	rc = lstat(filename, &st);
+
+	if (rc == 0) {
+		/* file exists */
+		if (S_ISREG(st.st_mode)) {
+			if (writable)
+				*writable = !try_write(filename, NULL);
+			return 1;
+		}
+		goto done;	/* it's not a regular file */
+	}
+
+	if (writable) {
+		char *dirname = strdup(filename);
+
+		if (!dirname)
+			goto done;
+
+		stripoff_last_component(dirname);	/* remove filename */
+
+		rc = mkdir(dirname, S_IWUSR|
+				    S_IRUSR|S_IRGRP|S_IROTH|
+				    S_IXUSR|S_IXGRP|S_IXOTH);
+		if (rc && errno != EEXIST) {
+			free(dirname);
+			goto done;			/* probably EACCES */
+		}
+
+		*writable = !try_write(filename, dirname);
+		free(dirname);
+		if (*writable)
+			return 1;
+	}
+done:
+	DBG(UTILS, ul_debug("%s: irregular/non-writable file", filename));
+	return 0;
+}
+
+/**
+ * mnt_get_swaps_path:
+ *
+ * Returns: path to /proc/swaps or $LIBMOUNT_SWAPS.
+ */
+const char *mnt_get_swaps_path(void)
+{
+	const char *p = safe_getenv("LIBMOUNT_SWAPS");
+	return p ? : _PATH_PROC_SWAPS;
+}
+
+/**
+ * mnt_get_fstab_path:
+ *
+ * Returns: path to /etc/fstab or $LIBMOUNT_FSTAB.
+ */
+const char *mnt_get_fstab_path(void)
+{
+	const char *p = safe_getenv("LIBMOUNT_FSTAB");
+	return p ? : _PATH_MNTTAB;
+}
+
+/**
+ * mnt_get_mtab_path:
+ *
+ * This function returns the *default* location of the mtab file. The result does
+ * not have to be writable. See also mnt_has_regular_mtab().
+ *
+ * Returns: path to /etc/mtab or $LIBMOUNT_MTAB.
+ */
+const char *mnt_get_mtab_path(void)
+{
+	const char *p = safe_getenv("LIBMOUNT_MTAB");
+	return p ? : _PATH_MOUNTED;
+}
+
+/*
+ * Don't export this to libmount API -- utab is private library stuff.
+ *
+ * Returns: path to /run/mount/utab (or /dev/.mount/utab) or $LIBMOUNT_UTAB.
+ */
+const char *mnt_get_utab_path(void)
+{
+	struct stat st;
+	const char *p = safe_getenv("LIBMOUNT_UTAB");
+
+	if (p)
+		return p;
+
+	if (stat(MNT_RUNTIME_TOPDIR, &st) == 0)
+		return MNT_PATH_UTAB;
+
+	return MNT_PATH_UTAB_OLD;
+}
+
+
+/* returns file descriptor or -errno, @name returns a unique filename
+ */
+int mnt_open_uniq_filename(const char *filename, char **name)
+{
+	int rc, fd;
+	char *n;
+	mode_t oldmode;
+
+	if (!filename)
+		return -EINVAL;
+	if (name)
+		*name = NULL;
+
+	rc = asprintf(&n, "%s.XXXXXX", filename);
+	if (rc <= 0)
+		return -errno;
+
+	/* This is for very old glibc and for compatibility with Posix, which says
+	 * nothing about mkstemp() mode. All sane glibc use secure mode (0600).
+	 */
+	oldmode = umask(S_IRGRP|S_IWGRP|S_IXGRP|
+			S_IROTH|S_IWOTH|S_IXOTH);
+	fd = mkostemp(n, O_RDWR|O_CREAT|O_EXCL|O_CLOEXEC);
+	if (fd < 0)
+		fd = -errno;
+	umask(oldmode);
+
+	if (fd >= 0 && name)
+		*name = n;
+	else
+		free(n);
+
+	return fd;
+}
+
+/**
+ * mnt_get_mountpoint:
+ * @path: pathname
+ *
+ * This function finds the mountpoint that a given path resides in. @path
+ * should be canonicalized. The returned pointer should be freed by the caller.
+ *
+ * WARNING: the function compares st_dev of the @path elements. This traditional
+ * way may be insufficient on filesystems like Linux "overlay". See also
+ * mnt_table_find_target().
+ *
+ * Returns: allocated string with the target of the mounted device or NULL on error
+ */
+char *mnt_get_mountpoint(const char *path)
+{
+	char *mnt;
+	struct stat st;
+	dev_t dir, base;
+
+	if (!path)
+		return NULL;
+
+	mnt = strdup(path);
+	if (!mnt)
+		return NULL;
+	if (*mnt == '/' && *(mnt + 1) == '\0')
+		goto done;
+
+	if (mnt_stat_mountpoint(mnt, &st))
+		goto err;
+	base = st.st_dev;
+
+	do {
+		char *p = stripoff_last_component(mnt);
+
+		if (!p)
+			break;
+		if (mnt_stat_mountpoint(*mnt ? mnt : "/", &st))
+			goto err;
+		dir = st.st_dev;
+		if (dir != base) {
+			if (p > mnt)
+				*(p - 1) = '/';
+			goto done;
+		}
+		base = dir;
+	} while (mnt && *(mnt + 1) != '\0');
+
+	memcpy(mnt, "/", 2);
+done:
+	DBG(UTILS, ul_debug("%s mountpoint is %s", path, mnt));
+	return mnt;
+err:
+	free(mnt);
+	return NULL;
+}
+
+/*
+ * Search for @name kernel command parameter.
+ *
+ * Returns newly allocated string with a parameter argument if the @name is
+ * specified as "name=" or returns pointer to @name or returns NULL if not
+ * found.  If it is specified more than once, we grab the last copy.
+ *
+ * For example cmdline: "aaa bbb=BBB ccc"
+ *
+ *	@name is "aaa"	--returns--> "aaa" (pointer to @name)
+ *	@name is "bbb=" --returns--> "BBB" (allocated)
+ *	@name is "foo"  --returns--> NULL
+ *
+ * Note: It is not really feasible to parse the command line exactly the same
+ * as the kernel does since we don't know which options are valid.  We can use
+ * the -- marker though and not walk past that.
+ */
+char *mnt_get_kernel_cmdline_option(const char *name)
+{
+	FILE *f;
+	size_t len;
+	int val = 0;
+	char *p, *res = NULL, *mem = NULL;
+	char buf[BUFSIZ];	/* see kernel include/asm-generic/setup.h: COMMAND_LINE_SIZE */
+	const char *path = _PATH_PROC_CMDLINE;
+
+	if (!name || !name[0])
+		return NULL;
+
+#ifdef TEST_PROGRAM
+	path = getenv("LIBMOUNT_KERNEL_CMDLINE");
+	if (!path)
+		path = _PATH_PROC_CMDLINE;
+#endif
+	f = fopen(path, "r" UL_CLOEXECSTR);
+	if (!f)
+		return NULL;
+
+	p = fgets(buf, sizeof(buf), f);
+	fclose(f);
+
+	if (!p || !*p || *p == '\n')
+		return NULL;
+
+	p = strstr(p, " -- ");
+	if (p) {
+		/* no more kernel args after this */
+		*p = '\0';
+	} else {
+		len = strlen(buf);
+		buf[len - 1] = '\0';	/* remove last '\n' */
+	}
+
+	len = strlen(name);
+	if (name[len - 1] == '=')
+		val = 1;
+
+	for (p = buf; p && *p; p++) {
+		if (!(p = strstr(p, name)))
+			break;			/* not found the option */
+		if (p != buf && !isblank(*(p - 1)))
+			continue;		/* no space before the option */
+		if (!val && *(p + len) != '\0' && !isblank(*(p + len)))
+			continue;		/* no space after the option */
+		if (val) {
+			char *v = p + len;
+			int end;
+
+			while (*p && !isblank(*p))	/* jump to the end of the argument */
+				p++;
+			end = (*p == '\0');
+			*p = '\0';
+			free(mem);
+			res = mem = strdup(v);
+			if (end)
+				break;
+		} else
+			res = (char *) name;	/* option without '=' */
+		/* don't break -- keep scanning for more options */
+	}
+
+	return res;
+}
+
+/**
+ * mnt_guess_system_root:
+ * @devno: device number or zero
+ * @cache: paths cache or NULL
+ * @path: returns allocated path
+ *
+ * Converts @devno to the real device name if devno major number is greater
+ * than zero, otherwise use root= kernel cmdline option to get device name.
+ *
+ * The function uses /sys to convert devno to device name.
+ *
+ * Returns: 0 = success, 1 = not found, <0 = error
+ *
+ * Since: 2.34
+ */
+int mnt_guess_system_root(dev_t devno, struct libmnt_cache *cache, char **path)
+{
+	char buf[PATH_MAX];
+	char *dev = NULL, *spec = NULL;
+	unsigned int x, y;
+	int allocated = 0;
+
+	assert(path);
+
+	DBG(UTILS, ul_debug("guessing system root [devno %u:%u]", major(devno), minor(devno)));
+
+	/* The pseudo-fs, net-fs or btrfs devno is useless, otherwise it
+	 * usually matches with the source device, let's try to use it.
+	 */
+	if (major(devno) > 0) {
+		dev = sysfs_devno_to_devpath(devno, buf, sizeof(buf));
+		if (dev) {
+			DBG(UTILS, ul_debug("  devno converted to %s", dev));
+			goto done;
+		}
+	}
+
+	/* Let's try to use root= kernel command line option
+	 */
+	spec = mnt_get_kernel_cmdline_option("root=");
+	if (!spec)
+		goto done;
+
+	/* maj:min notation */
+	if (sscanf(spec, "%u:%u", &x, &y) == 2) {
+		dev = sysfs_devno_to_devpath(makedev(x, y), buf, sizeof(buf));
+		if (dev) {
+			DBG(UTILS, ul_debug("  root=%s converted to %s", spec, dev));
+			goto done;
+		}
+
+	/* hexhex notation */
+	} else if (isxdigit_string(spec)) {
+		char *end = NULL;
+		uint32_t n;
+
+		errno = 0;
+		n = strtoul(spec, &end, 16);
+
+		if (errno || spec == end || (end && *end))
+			DBG(UTILS, ul_debug("  failed to parse root='%s'", spec));
+		else {
+			/* kernel new_decode_dev() */
+			x = (n & 0xfff00) >> 8;
+			y = (n & 0xff) | ((n >> 12) & 0xfff00);
+			dev = sysfs_devno_to_devpath(makedev(x, y), buf, sizeof(buf));
+			if (dev) {
+				DBG(UTILS, ul_debug("  root=%s converted to %s", spec, dev));
+				goto done;
+			}
+		}
+
+	/* devname or PARTUUID= etc. */
+	} else {
+		DBG(UTILS, ul_debug("  converting root='%s'", spec));
+
+		dev = mnt_resolve_spec(spec, cache);
+		if (dev && !cache)
+			allocated = 1;
+	}
+done:
+	free(spec);
+	if (dev) {
+		*path = allocated ? dev : strdup(dev);
+		if (!*path)
+			return -ENOMEM;
+		return 0;
+	}
+
+	return 1;
+}
+
+#if defined(HAVE_FMEMOPEN) || defined(TEST_PROGRAM)
+
+/*
+ * This function tries to minimize possible races when we read
+ * /proc/#/{mountinfo,mount} files.
+ *
+ * The idea is to minimize number of read()s and check by poll() that during
+ * the read the mount table has not been modified. If yes, than re-read it
+ * (with some limitations to avoid never ending loop).
+ *
+ * Returns: <0 error, 0 success, 1 too many attempts
+ */
+static int read_procfs_file(int fd, char **buf, size_t *bufsiz)
+{
+	size_t bufmax = 0;
+	int rc = 0, tries = 0, ninters = 0;
+	char *bufptr = NULL;
+
+	assert(buf);
+	assert(bufsiz);
+
+	*bufsiz = 0;
+	*buf = NULL;
+
+	do {
+		ssize_t ret;
+
+		if (!bufptr || bufmax == *bufsiz) {
+			char *tmp;
+
+			bufmax = bufmax ? bufmax * 2 : (16 * 1024);
+			tmp = realloc(*buf, bufmax);
+			if (!tmp)
+				break;
+			*buf = tmp;
+			bufptr = tmp + *bufsiz;
+		}
+
+		errno = 0;
+		ret = read(fd, bufptr, bufmax - *bufsiz);
+
+		if (ret < 0) {
+			/* error */
+			if ((errno == EAGAIN || errno == EINTR) && (ninters++ < 5)) {
+				xusleep(200000);
+				continue;
+			}
+			break;
+
+		} if (ret > 0) {
+			/* success -- verify no event during read */
+			struct pollfd fds[] = {
+				{ .fd = fd, .events = POLLPRI }
+			};
+
+			rc = poll(fds, 1, 0);
+			if (rc < 0)
+				break;		/* poll() error */
+			if (rc > 0) {
+				/* event -- read all again */
+				if (lseek(fd, 0, SEEK_SET) != 0)
+					break;
+				*bufsiz = 0;
+				bufptr = *buf;
+				tries++;
+
+				if (tries > 10)
+					/* busy system? -- wait */
+					xusleep(10000);
+				continue;
+			}
+
+			/* successful read() without active poll() */
+			(*bufsiz) += (size_t) ret;
+			bufptr += ret;
+			tries = ninters = 0;
+		} else {
+			/* end-of-file */
+			goto success;
+		}
+	} while (tries <= 100);
+
+	rc = errno ? -errno : 1;
+	free(*buf);
+	return rc;
+
+success:
+	return 0;
+}
+
+/*
+ * Create FILE stream for data from read_procfs_file()
+ */
+FILE *mnt_get_procfs_memstream(int fd, char **membuf)
+{
+	size_t sz = 0;
+	off_t cur;
+
+	*membuf = NULL;
+
+	/* in case of error, rewind to the original position */
+	cur = lseek(fd, 0, SEEK_CUR);
+
+	if (read_procfs_file(fd, membuf, &sz) == 0 && sz > 0) {
+		FILE *memf = fmemopen(*membuf, sz, "r");
+		if (memf)
+			return memf;	/* success */
+
+		free(*membuf);
+		*membuf = NULL;
+	}
+
+	/* error */
+	if (cur != (off_t) -1)
+		lseek(fd, cur, SEEK_SET);
+	return NULL;
+}
+#else
+FILE *mnt_get_procfs_memstream(int fd __attribute((__unused__)),
+		               char **membuf __attribute((__unused__)))
+{
+	return NULL;
+}
+#endif /* HAVE_FMEMOPEN */
+
+
+#ifdef TEST_PROGRAM
+static int test_proc_read(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char *buf = NULL;
+	char *filename = argv[1];
+	size_t bufsiz = 0;
+	int rc = 0, fd = open(filename, O_RDONLY);
+
+	if (fd <= 0) {
+		warn("%s: cannot open", filename);
+		return -errno;
+	}
+
+	rc = read_procfs_file(fd, &buf, &bufsiz);
+	close(fd);
+
+	switch (rc) {
+	case 0:
+		fwrite(buf, 1, bufsiz, stdout);
+		free(buf);
+		break;
+	case 1:
+		warnx("too many attempts");
+		break;
+	default:
+		warn("%s: cannot read", filename);
+		break;
+	}
+
+	return rc;
+}
+
+static int test_match_fstype(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char *type = argv[1];
+	char *pattern = argv[2];
+
+	printf("%s\n", mnt_match_fstype(type, pattern) ? "MATCH" : "NOT-MATCH");
+	return 0;
+}
+
+static int test_match_options(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char *optstr = argv[1];
+	char *pattern = argv[2];
+
+	printf("%s\n", mnt_match_options(optstr, pattern) ? "MATCH" : "NOT-MATCH");
+	return 0;
+}
+
+static int test_startswith(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char *optstr = argv[1];
+	char *pattern = argv[2];
+
+	printf("%s\n", startswith(optstr, pattern) ? "YES" : "NOT");
+	return 0;
+}
+
+static int test_endswith(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char *optstr = argv[1];
+	char *pattern = argv[2];
+
+	printf("%s\n", endswith(optstr, pattern) ? "YES" : "NOT");
+	return 0;
+}
+
+static int test_appendstr(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char *str = strdup(argv[1]);
+	const char *ap = argv[2];
+
+	append_string(&str, ap);
+	printf("new string: '%s'\n", str);
+
+	free(str);
+	return 0;
+}
+
+static int test_mountpoint(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char *path = canonicalize_path(argv[1]),
+	     *mnt = path ? mnt_get_mountpoint(path) :  NULL;
+
+	printf("%s: %s\n", argv[1], mnt ? : "unknown");
+	free(mnt);
+	free(path);
+	return 0;
+}
+
+static int test_filesystems(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char **filesystems = NULL;
+	int rc;
+
+	rc = mnt_get_filesystems(&filesystems, argc ? argv[1] : NULL);
+	if (!rc) {
+		char **p;
+		for (p = filesystems; *p; p++)
+			printf("%s\n", *p);
+		mnt_free_filesystems(filesystems);
+	}
+	return rc;
+}
+
+static int test_chdir(struct libmnt_test *ts, int argc, char *argv[])
+{
+	int rc;
+	char *path = canonicalize_path(argv[1]),
+	     *last = NULL;
+
+	if (!path)
+		return -errno;
+
+	rc = mnt_chdir_to_parent(path, &last);
+	if (!rc) {
+		printf("path='%s', abs='%s', last='%s'\n",
+				argv[1], path, last);
+	}
+	free(path);
+	free(last);
+	return rc;
+}
+
+static int test_kernel_cmdline(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char *name = argv[1];
+	char *res;
+
+	res = mnt_get_kernel_cmdline_option(name);
+	if (!res)
+		printf("'%s' not found\n", name);
+	else if (res == name)
+		printf("'%s' found\n", name);
+	else {
+		printf("'%s' found, argument: '%s'\n", name, res);
+		free(res);
+	}
+
+	return 0;
+}
+
+
+static int test_guess_root(struct libmnt_test *ts, int argc, char *argv[])
+{
+	int rc;
+	char *real;
+	dev_t devno = 0;
+
+	if (argc) {
+		unsigned int x, y;
+
+		if (sscanf(argv[1], "%u:%u", &x, &y) != 2)
+			return -EINVAL;
+		devno = makedev(x, y);
+	}
+
+	rc = mnt_guess_system_root(devno, NULL, &real);
+	if (rc < 0)
+		return rc;
+	if (rc == 1)
+		fputs("not found\n", stdout);
+	else {
+		printf("%s\n", real);
+		free(real);
+	}
+	return 0;
+}
+
+static int test_mkdir(struct libmnt_test *ts, int argc, char *argv[])
+{
+	int rc;
+
+	rc = mkdir_p(argv[1], S_IRWXU |
+			 S_IRGRP | S_IXGRP |
+			 S_IROTH | S_IXOTH);
+	if (rc)
+		printf("mkdir %s failed\n", argv[1]);
+	return rc;
+}
+
+static int test_statfs_type(struct libmnt_test *ts, int argc, char *argv[])
+{
+	struct statfs vfs;
+	int rc;
+
+	rc = statfs(argv[1], &vfs);
+	if (rc)
+		printf("%s: statfs failed: %m\n", argv[1]);
+	else
+		printf("%-30s: statfs type: %-12s [0x%lx]\n", argv[1],
+				mnt_statfs_get_fstype(&vfs),
+				(long) vfs.f_type);
+	return rc;
+}
+
+
+int main(int argc, char *argv[])
+{
+	struct libmnt_test tss[] = {
+	{ "--match-fstype",  test_match_fstype,    "<type> <pattern>     FS types matching" },
+	{ "--match-options", test_match_options,   "<options> <pattern>  options matching" },
+	{ "--filesystems",   test_filesystems,	   "[<pattern>] list /{etc,proc}/filesystems" },
+	{ "--starts-with",   test_startswith,      "<string> <prefix>" },
+	{ "--ends-with",     test_endswith,        "<string> <prefix>" },
+	{ "--append-string", test_appendstr,       "<string> <appendix>" },
+	{ "--mountpoint",    test_mountpoint,      "<path>" },
+	{ "--cd-parent",     test_chdir,           "<path>" },
+	{ "--kernel-cmdline",test_kernel_cmdline,  "<option> | <option>=" },
+	{ "--guess-root",    test_guess_root,      "[<maj:min>]" },
+	{ "--mkdir",         test_mkdir,           "<path>" },
+	{ "--statfs-type",   test_statfs_type,     "<path>" },
+	{ "--read-procfs",   test_proc_read,       "<path>" },
+
+	{ NULL }
+	};
+
+	return mnt_run_test(tss, argc, argv);
+}
+
+#endif /* TEST_PROGRAM */