libmount: add first part of high-level API

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 1126 insertions, 0 deletions

diff --git a/shlibs/mount/src/context.c b/shlibs/mount/src/context.c
new file mode 100644
index 000000000..f2c26cbc7
--- /dev/null
+++ b/shlibs/mount/src/context.c
@@ -0,0 +1,1126 @@
+/*
+ * Copyright (C) 2010 Karel Zak <kzak@redhat.com>
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+#include "c.h"
+#include "mountP.h"
+
+
+/*
+ * Mount context -- high-level API
+ */
+struct _mnt_context
+{
+	int	action;		/* MNT_ACT_{MOUNT,UMOUNT} */
+
+	int	restricted;	/* root or not? */
+
+	char	*fstype_pattern;	/* for mnt_match_fstype() */
+	char	*optstr_pattern;	/* for mnt_match_options() */
+
+	char	*spec;		/* unresolved source OR target */
+	mnt_fs	*fs;		/* filesystem description (type, mountpopint, device, ...) */
+
+	mnt_tab	*fstab;		/* fstab (or mtab for some remounts) entires */
+	mnt_tab *mtab;		/* mtab entries */
+	int	optsmode;	/* fstab optstr mode MNT_OPTSMODE_{AUTO,FORCE,IGNORE} */
+
+	unsigned long	mountflags;	/* final mount(2) flags */
+	const void	*mountdata;	/* final mount(2) data, string or binary data */
+
+	unsigned long	user_mountflags;	/* MNT_MS_* (loop=, user=, ...) */
+
+	mnt_update	*update;	/* mtab update */
+	mnt_cache	*cache;		/* paths cache */
+
+	int	flags;		/* private context flags */
+};
+
+/* flags */
+#define MNT_FL_NOMTAB		(1 << 1)
+#define MNT_FL_FAKE		(1 << 2)
+#define MNT_FL_SLOPPY		(1 << 3)
+#define MNT_FL_VERBOSE		(1 << 4)
+#define MNT_FL_NOHELPERS	(1 << 5)
+#define MNT_FL_LOOPDEL		(1 << 6)
+#define MNT_FL_LAZY		(1 << 7)
+#define MNT_FL_FORCE		(1 << 8)
+#define MNT_FL_NOCANONICALIZE	(1 << 9)
+
+#define MNT_FL_EXTERN_FS	(1 << 15)	/* cxt->fs is not private */
+#define MNT_FL_EXTERN_FSTAB	(1 << 16)	/* cxt->fstab is not private */
+#define MNT_FL_EXTERN_CACHE	(1 << 17)	/* cxt->cache is not private */
+
+#define MNT_FL_MOUNTDATA	(1 << 20)
+#define MNT_FL_FSTAB_APPLIED	(1 << 21)
+#define MNT_FL_MOUNTFLAGS_MERGED (1 << 22)	/* MS_* flags was read from optstr */
+
+/* default flags */
+#define MNT_FL_DEFAULT		0
+
+/* mode for mount options from fstab */
+enum {
+	MNT_OPTSMODE_AUTO = 0,		/* use options if source or target are not defined */
+	MNT_OPTSMODE_IGNORE,		/* never use mount options from fstab */
+	MNT_OPTSMODE_FORCE,		/* always use mount options from fstab */
+	MNT_OPTSMODE_MTABFORCE,		/* for MS_REMOUNT use always options mountinfo/mtab */
+};
+
+/**
+ * mnt_new_context:
+ *
+ * Returns: newly allocated mount context
+ */
+mnt_context *mnt_new_context()
+{
+	mnt_context *cxt;
+	uid_t ruid, euid;
+
+	cxt = calloc(1, sizeof(*cxt));
+	if (!cxt)
+		return NULL;
+
+	ruid = getuid();
+	euid = geteuid();
+
+	/* if we're really root and aren't running setuid */
+	cxt->restricted = (uid_t) 0 == ruid && ruid == euid ? 0 : 1;
+
+	DBG(CXT, mnt_debug_h(cxt, "allocate"));
+
+	return cxt;
+}
+
+/**
+ * mnt_free_context:
+ * @cxt: mount context
+ *
+ * Deallocates context struct.
+ */
+void mnt_free_context(mnt_context *cxt)
+{
+	if (!cxt)
+		return;
+
+	DBG(CXT, mnt_debug_h(cxt, "free"));
+
+	free(cxt->fstype_pattern);
+	free(cxt->optstr_pattern);
+	free(cxt->spec);
+
+	if (!(cxt->flags & MNT_FL_EXTERN_FS))
+		mnt_free_fs(cxt->fs);
+	if (!(cxt->flags & MNT_FL_EXTERN_FSTAB))
+		mnt_free_tab(cxt->fstab);
+	if (!(cxt->flags & MNT_FL_EXTERN_CACHE))
+		mnt_free_cache(cxt->cache);
+
+	mnt_free_update(cxt->update);
+	mnt_free_tab(cxt->mtab);
+
+	free(cxt);
+}
+
+/**
+ * mnt_reset_context:
+ * @cxt: mount context
+ *
+ * Resets all information in the context that are directly related to
+ * the latest mount (spec, source, target, mount options, ....)
+ *
+ * The match patters, cached fstab, cached canonicalized paths and tags and
+ * [e]uid are not reseted. You have to use
+ *
+ *	mnt_context_set_fstab(cxt, NULL);
+ *	mnt_context_set_cache(cxt, NULL);
+ *	mnt_context_set_fstype_pattern(cxt, NULL);
+ *	mnt_context_set_optstr_pattern(cxt, NULL);
+ *
+ * to reset these stuff.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_reset_context(mnt_context *cxt)
+{
+	int fl;
+
+	if (!cxt)
+		return -EINVAL;
+
+	fl = cxt->flags;
+
+	if (cxt->update)
+		mnt_update_set_fs(cxt->update, NULL);
+
+	if (!(cxt->flags & MNT_FL_EXTERN_FS))
+		mnt_free_fs(cxt->fs);
+
+	mnt_free_tab(cxt->mtab);
+
+	cxt->fs = NULL;
+	cxt->mtab = NULL;
+
+	free(cxt->spec);
+	cxt->spec = NULL;
+
+	cxt->mountflags = 0;
+	cxt->user_mountflags = 0;
+	cxt->mountdata = NULL;
+	cxt->flags = MNT_FL_DEFAULT;
+
+	/* restore non-resetable flags */
+	cxt->flags |= (fl & MNT_FL_EXTERN_FSTAB);
+	cxt->flags |= (fl & MNT_FL_EXTERN_CACHE);
+
+	return 0;
+}
+
+static int mnt_context_set_flag(mnt_context *cxt, int flag, int enable)
+{
+	if (!cxt)
+		return -EINVAL;
+	if (enable)
+		cxt->flags |= flag;
+	else
+		cxt->flags &= ~flag;
+	return 0;
+}
+
+static mnt_fs *mnt_context_get_fs(mnt_context *cxt)
+{
+	if (!cxt)
+		return NULL;
+	if (!cxt->fs) {
+		cxt->fs = mnt_new_fs();
+		cxt->flags &= ~MNT_FL_EXTERN_FS;
+	}
+	return cxt->fs;
+}
+
+/**
+ * mnt_context_is_restricted:
+ * @cxt: mount context
+ *
+ * Returns: 0 for unrestricted mount (user is root), or 1 for non-root mounts
+ */
+int mnt_context_is_restricted(mnt_context *cxt)
+{
+	assert(cxt);
+	return cxt->restricted;
+}
+
+/**
+ * mnt_context_set_optsmode
+ * @cxt: mount context
+ * @mode: MNT_OPTSMODE_{AUTO,FORCE,IGNORE,MTABFORCE}
+ *
+ * Defines a mode how libmount uses fstab mount options:
+ *
+ *  auto       - use options from fstab if source or target are not
+ *               defined (this is mount(8) default).
+ *
+ *             - For remount operation it reads options from mtab if
+ *               the target is not found in fstab.
+ *
+ *  ignore     - never use mount options from fstab
+ *
+ *  force      - always use mount options from fstab
+ *
+ *  mtab-force - for remount operation always use options from mtab (mountinfo)
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_optsmode(mnt_context *cxt, int mode)
+{
+	if (!cxt)
+		return -EINVAL;
+	cxt->optsmode = mode;
+	return 0;
+}
+
+/**
+ * mnt_context_disable_canonicalize:
+ * @cxt: mount context
+ * @disable: TRUE or FALSE
+ *
+ * Enable/disable paths canonicalization and tags evaluation. The libmount context
+ * canonicalies paths when search in fstab and when prepare source and target paths
+ * for mount(2) syscall.
+ *
+ * This fuction has effect to the private fstab instance only (see
+ * mnt_context_set_fstab()). If you want to use an external fstab then you need
+ * manage your private mnt_cache (see mnt_tab_set_cache(fstab, NULL).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_disable_canonicalize(mnt_context *cxt, int disable)
+{
+	return mnt_context_set_flag(cxt, MNT_FL_NOCANONICALIZE, disable);
+}
+
+/**
+ * mnt_context_enable_lazy:
+ * @cxt: mount context
+ * @enable: TRUE or FALSE
+ *
+ * Enable/disable lazy umount (see umount(8) man page, option -l).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_enable_lazy(mnt_context *cxt, int enable)
+{
+	return mnt_context_set_flag(cxt, MNT_FL_LAZY, enable);
+}
+
+/**
+ * mnt_context_disable_helpers:
+ * @cxt: mount context
+ * @disable: TRUE or FALSE
+ *
+ * Enable/disable /sbin/[u]mount.* helpers (see mount(8) man page, option -i).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_disable_helpers(mnt_context *cxt, int disable)
+{
+	return mnt_context_set_flag(cxt, MNT_FL_NOHELPERS, disable);
+}
+
+/**
+ * mnt_context_enable_sloppy:
+ * @cxt: mount context
+ * @enable: TRUE or FALSE
+ *
+ * Set/unset sloppy mounting (see mount(8) man page, option -s).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_enable_sloppy(mnt_context *cxt, int enable)
+{
+	return mnt_context_set_flag(cxt, MNT_FL_SLOPPY, enable);
+}
+
+/**
+ * mnt_context_enable_fake:
+ * @cxt: mount context
+ * @enable: TRUE or FALSE
+ *
+ * Enable/disable fake mounting (see mount(8) man page, option -f).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_enable_fake(mnt_context *cxt, int enable)
+{
+	return mnt_context_set_flag(cxt, MNT_FL_FAKE, enable);
+}
+
+/**
+ * mnt_context_disable_mtab:
+ * @cxt: mount context
+ * @disable: TRUE or FALSE
+ *
+ * Disable/enable mtab update (see mount(8) man page, option -n).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_disable_nomtab(mnt_context *cxt, int disable)
+{
+	return mnt_context_set_flag(cxt, MNT_FL_NOMTAB, disable);
+}
+
+/**
+ * mnt_context_enable_force:
+ * @cxt: mount context
+ * @enable: TRUE or FALSE
+ *
+ * Enable/disable force umounting (see umount(8) man page, option -f).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_enable_force(mnt_context *cxt, int enable)
+{
+	return mnt_context_set_flag(cxt, MNT_FL_FORCE, enable);
+}
+
+/**
+ * mnt_context_enable_verbose:
+ * @cxt: mount context
+ * @enable: TRUE or FALSE
+ *
+ * Enable/disable verbose output.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_enable_verbose(mnt_context *cxt, int enable)
+{
+	return mnt_context_set_flag(cxt, MNT_FL_VERBOSE, enable);
+}
+
+/**
+ * mnt_context_enable_loopdel:
+ * @cxt: mount context
+ * @enable: TRUE or FALSE
+ *
+ * Enable/disable loop delete (destroy) after umount (see umount(8), option -d)
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_enable_loopdel(mnt_context *cxt, int enable)
+{
+	return mnt_context_set_flag(cxt, MNT_FL_LOOPDEL, enable);
+}
+
+/**
+ * mnt_context_set_spec:
+ * @cxt: mount context
+ * @spec: unresolved source (device, label, uuid, ...) or target (mountpoint)
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_spec(mnt_context *cxt, const char *spec)
+{
+	char *p;
+
+	if (!cxt)
+		return -EINVAL;
+	p = strdup(spec);
+	if (!p)
+		return -ENOMEM;
+	free(cxt->spec);
+	cxt->spec = p;
+	return 0;
+}
+
+/**
+ * mnt_context_set_fs:
+ * @cxt: mount context
+ * @fs: filesystem description
+ *
+ * The mount context uses private @fs by default. This function allows to
+ * overwrite the private @fs with an external instance. Note that the external
+ * @fs instance is not deallocated by mnt_free_context() or mnt_reset_context().
+ *
+ * The @fs will be modified by mnt_context_set_{source,target,optstr,fstype}
+ * functions, Ft the @fs is NULL then all current FS specific setting (source,
+ * target, etc., exclude spec) is reseted.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_fs(mnt_context *cxt, mnt_fs *fs)
+{
+	if (!cxt)
+		return -EINVAL;
+	if (!(cxt->flags & MNT_FL_EXTERN_FS))
+		mnt_free_fs(cxt->fs);
+
+	mnt_context_set_flag(cxt, MNT_FL_EXTERN_FS, fs != NULL);
+	cxt->fs = fs;
+	return 0;
+}
+
+/**
+ * mnt_context_set_source:
+ * @cxt: mount context
+ * @source: mount source (device, directory, UUID, LABEL, ...)
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_source(mnt_context *cxt, const char *source)
+{
+	return mnt_fs_set_source(mnt_context_get_fs(cxt), source);
+}
+
+/**
+ * mnt_context_set_target:
+ * @cxt: mount context
+ * @target: mountpoint
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_target(mnt_context *cxt, const char *target)
+{
+	return mnt_fs_set_target(mnt_context_get_fs(cxt), target);
+}
+
+/**
+ * mnt_context_set_fstype:
+ * @cxt: mount context
+ * @fstype: filesystem type
+ *
+ * Note that the @fstype has to be the real FS type. For comma-separated list of
+ * filesystems or for "no<fs>" notation use mnt_context_set_fstype_pattern().
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_fstype(mnt_context *cxt, const char *fstype)
+{
+	return mnt_fs_set_fstype(mnt_context_get_fs(cxt), fstype);
+}
+
+/**
+ * mnt_context_set_optstr:
+ * @cxt: mount context
+ * @optstr: comma delimited mount options
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_optstr(mnt_context *cxt, const char *optstr)
+{
+	return mnt_fs_set_optstr(mnt_context_get_fs(cxt), optstr);
+}
+
+/**
+ * mnt_context_append_optstr:
+ * @cxt: mount context
+ * @optstr: comma delimited mount options
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_append_optstr(mnt_context *cxt, const char *optstr)
+{
+	return mnt_fs_append_optstr(mnt_context_get_fs(cxt), optstr);
+}
+
+/**
+ * mnt_context_set_fstype_pattern:
+ * @cxt: mount context
+ * @pattern: FS name pattern (or NULL to reset the current setting)
+ *
+ * See mount(8), option -t.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_fstype_pattern(mnt_context *cxt, const char *pattern)
+{
+	char *p = NULL;
+
+	if (!cxt)
+		return -EINVAL;
+	if (pattern) {
+		p = strdup(pattern);
+		if (!p)
+			return -ENOMEM;
+	}
+	free(cxt->fstype_pattern);
+	cxt->fstype_pattern = p;
+	return 0;
+}
+
+/**
+ * mnt_context_set_optstr_pattern:
+ * @cxt: mount context
+ * @pattern: options pattern (or NULL to reset the current setting)
+ *
+ * See mount(8), option -O.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_optstr_pattern(mnt_context *cxt, const char *pattern)
+{
+	char *p = NULL;
+
+	if (!cxt)
+		return -EINVAL;
+	if (pattern) {
+		p = strdup(pattern);
+		if (!p)
+			return -ENOMEM;
+	}
+	free(cxt->optstr_pattern);
+	cxt->optstr_pattern = p;
+	return 0;
+}
+
+/**
+ * mnt_context_set_fstab:
+ * @cxt: mount context
+ * @tb: fstab
+ *
+ * The mount context reads /etc/fstab to the the private mnt_tab by default.
+ * This function allows to overwrite the private fstab with an external
+ * instance. Note that the external instance is not deallocated by mnt_free_context().
+ *
+ * The fstab is used read-only and is not modified, it should be possible to
+ * share the fstab between more mount contexts (TODO: tests it.)
+ *
+ * If the @tb argument is NULL then the current private fstab instance is
+ * reseted.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_fstab(mnt_context *cxt, mnt_tab *tb)
+{
+	if (!cxt)
+		return -EINVAL;
+	if (!(cxt->flags & MNT_FL_EXTERN_FSTAB))
+		mnt_free_tab(cxt->fstab);
+
+	mnt_context_set_flag(cxt, MNT_FL_EXTERN_FSTAB, tb != NULL);
+	cxt->fstab = tb;
+	return 0;
+}
+
+/**
+ * mnt_context_set_cache:
+ * @cxt: mount context
+ * @cache: cache instance or nULL
+ *
+ * The mount context maintains a private mnt_cache by default.  This function
+ * allows to overwrite the private cache with an external instance. Note that
+ * the external instance is not deallocated by mnt_free_context().
+ *
+ * If the @cache argument is NULL then the current private cache instance is
+ * reseted.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_cache(mnt_context *cxt, mnt_cache *cache)
+{
+	if (!cxt)
+		return -EINVAL;
+	if (!(cxt->flags & MNT_FL_EXTERN_CACHE))
+		mnt_free_cache(cxt->cache);
+
+	mnt_context_set_flag(cxt, MNT_FL_EXTERN_CACHE, cache != NULL);
+	cxt->cache = cache;
+	return 0;
+}
+
+static mnt_cache *mnt_context_get_cache(mnt_context *cxt)
+{
+	if (!cxt || (cxt->flags & MNT_FL_NOCANONICALIZE))
+		return NULL;
+
+	if (!cxt->cache) {
+		cxt->cache = mnt_new_cache();
+		if (!cxt->cache)
+			return NULL;
+		cxt->flags &= ~MNT_FL_EXTERN_CACHE;
+	}
+	return cxt->cache;
+}
+
+/**
+ * mnt_context_set_mountflags:
+ * @cxt: mount context
+ * @flags: mount(2) flags (MS_* flags)
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_mountflags(mnt_context *cxt, unsigned long flags)
+{
+	if (!cxt)
+		return -EINVAL;
+	cxt->mountflags = flags;
+	return 0;
+}
+
+/**
+ * mnt_context_get_mountflags:
+ * @cxt: mount context
+ * @flags: returns mount flags
+ *
+ * Converts mount options string to MS_* flags and bitewise-OR the result with
+ * already defined flags (see mnt_context_set_mountflags()).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_get_mountflags(mnt_context *cxt, unsigned long *flags)
+{
+	int rc = 0;
+	if (!cxt || !flags)
+		return -EINVAL;
+
+	*flags = 0;
+	if (!(cxt->flags & MNT_FL_MOUNTFLAGS_MERGED) && cxt->fs) {
+		const char *o = mnt_fs_get_optstr(cxt->fs);
+		if (o)
+			rc = mnt_optstr_get_mountflags(o, flags);
+	}
+	if (!rc)
+		*flags |= cxt->mountflags;
+	return rc;
+}
+
+static int mnt_context_is_remount(mnt_context *cxt)
+{
+	unsigned long fl = 0;
+
+	if (cxt->mountflags & MS_REMOUNT)
+		return 1;
+	if (!mnt_context_get_mountflags(cxt, &fl) && (fl & MS_REMOUNT))
+		return 1;
+	return 0;
+}
+
+/**
+ * mnt_context_set_userspace_mountflags:
+ * @cxt: mount context
+ * @flags: mount(2) flags (MNT_MS_* flags, e.g. MNT_MS_LOOP)
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_userspace_mountflags(mnt_context *cxt, unsigned long flags)
+{
+	if (!cxt)
+		return -EINVAL;
+	cxt->user_mountflags = flags;
+	return 0;
+}
+
+/**
+ * mnt_context_get_userspace_mountflags:
+ * @cxt: mount context
+ * @flags: returns mount flags
+ *
+ * Converts mount options string to MNT_MS_* flags and bitewise-OR the result with
+ * already defined flags (see mnt_context_set_userspace_mountflags()).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_get_userspace_mountflags(mnt_context *cxt, unsigned long *flags)
+{
+	int rc = 0;
+	if (!cxt || !flags)
+		return -EINVAL;
+
+	*flags = 0;
+	if (!(cxt->flags & MNT_FL_MOUNTFLAGS_MERGED) && cxt->fs) {
+		const char *o = mnt_fs_get_optstr(cxt->fs);
+		if (o)
+			rc = mnt_optstr_get_userspace_mountflags(o, flags);
+	}
+	if (!rc)
+		*flags |= cxt->user_mountflags;
+	return rc;
+}
+
+static int mnt_context_is_loop(mnt_context *cxt)
+{
+	unsigned long fl = 0;
+
+	if (cxt->user_mountflags & MNT_MS_LOOP)
+		return 1;
+	if (!mnt_context_get_mountflags(cxt, &fl) && (fl & MNT_MS_LOOP))
+		return 1;
+
+	/* TODO:
+	 *	- support MNT_MS_{OFFSET,SIZELIMIT,ENCRYPTION}
+	 */
+	return 0;
+}
+
+
+/**
+ * mnt_context_set_mountdata:
+ * @cxt: mount context
+ * @data: mount(2) data
+ *
+ * The mount context generates mountdata from mount options by default. This
+ * function allows to overwrite this behavior, and @data will be used instead
+ * of mount options.
+ *
+ * The libmount does not deallocated the data by mnt_free_context(). Note that
+ * NULL is also valid mount data.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_set_mountdata(mnt_context *cxt, void *data)
+{
+	if (!cxt)
+		return -EINVAL;
+	cxt->mountdata = data;
+	cxt->flags |= MNT_FL_MOUNTDATA;
+	return 0;
+}
+
+static int mnt_context_apply_tab(mnt_context *cxt, mnt_tab *tb)
+{
+	mnt_fs *fs = NULL;
+	const char *src = NULL, *tgt = NULL;
+	int rc;
+
+	if (!cxt->fs)
+		return -EINVAL;
+
+	src = mnt_fs_get_source(cxt->fs);
+	tgt = mnt_fs_get_target(cxt->fs);
+
+	if (tgt && src)
+		;	/* TODO: search pair for MNT_OPTSMODE_FORCE */
+	else if (src)
+		fs = mnt_tab_find_source(tb, src, MNT_ITER_FORWARD);
+	else if (tgt)
+		fs = mnt_tab_find_target(tb, tgt, MNT_ITER_FORWARD);
+	else if (cxt->spec) {
+		fs = mnt_tab_find_source(tb, cxt->spec, MNT_ITER_FORWARD);
+
+		if (!fs && (strncmp(cxt->spec, "LABEL=", 6) ||
+			    strncmp(cxt->spec, "UUID=", 5)))
+			fs = mnt_tab_find_target(tb, cxt->spec, MNT_ITER_FORWARD);
+	}
+
+	if (!fs)
+		return -EINVAL;
+
+	DBG(CXT, mnt_debug_h(cxt, "apply entry:"));
+	DBG(CXT, mnt_fs_print_debug(fs, stderr));
+
+	/* copy from fstab to our FS description
+	 */
+	rc = mnt_fs_set_source(cxt->fs, mnt_fs_get_source(fs));
+	if (!rc)
+		rc = mnt_fs_set_target(cxt->fs, mnt_fs_get_target(fs));
+
+	if (!rc && !mnt_fs_get_fstype(cxt->fs))
+		rc = mnt_fs_set_fstype(cxt->fs, mnt_fs_get_fstype(fs));
+
+	if (!rc && cxt->optsmode != MNT_OPTSMODE_IGNORE)
+		rc = mnt_fs_prepend_optstr(cxt->fs, mnt_fs_get_optstr(fs));
+
+	if (!rc)
+		cxt->flags |= MNT_FL_FSTAB_APPLIED;
+
+	return rc;
+}
+
+int mnt_context_apply_fstab(mnt_context *cxt)
+{
+	int rc;
+	mnt_cache *cache;
+	const char *src = NULL, *tgt = NULL;
+
+	if (!cxt || (!cxt->spec && !cxt->fs))
+		return -EINVAL;
+
+	if (cxt->flags & MNT_FL_FSTAB_APPLIED)
+		return 0;
+
+	if (cxt->fs) {
+		src = mnt_fs_get_source(cxt->fs);
+		tgt = mnt_fs_get_target(cxt->fs);
+	}
+
+	/* fstab is not required if source and target are specified */
+	if (src && tgt && !(cxt->optsmode == MNT_OPTSMODE_FORCE ||
+			    cxt->optsmode == MNT_OPTSMODE_MTABFORCE))
+		return 0;
+
+	DBG(CXT, mnt_debug_h(cxt,
+		"trying to apply fstab (src=%s, target=%s, spec=%s)",
+		src, tgt, cxt->spec));
+
+	/* initialize fstab */
+	if (!cxt->fstab) {
+		cxt->fstab = mnt_new_tab();
+		if (!cxt->fstab)
+			goto errnomem;
+		cxt->flags &= ~MNT_FL_EXTERN_FSTAB;
+		rc = mnt_tab_parse_fstab(cxt->fstab);
+		if (rc)
+			goto err;
+	}
+
+	cache = mnt_context_get_cache(cxt);	/* NULL if MNT_FL_NOCANONICALIZE is enabled */
+
+	/*  never touch an external fstab */
+	if (!(cxt->flags & MNT_FL_EXTERN_FSTAB))
+		mnt_tab_set_cache(cxt->fstab, cache);
+
+	/* let's initialize cxt->fs */
+	mnt_context_get_fs(cxt);
+
+	/* try fstab */
+	rc = mnt_context_apply_tab(cxt, cxt->fstab);
+
+	/* try mtab */
+	if (rc || (cxt->optsmode == MNT_OPTSMODE_MTABFORCE &&
+		   mnt_context_is_remount(cxt))) {
+
+		cxt->mtab = mnt_new_tab();
+		if (!cxt->mtab)
+			goto errnomem;
+		rc = mnt_tab_parse_mtab(cxt->mtab);
+		if (rc)
+			goto err;
+
+		mnt_tab_set_cache(cxt->mtab, cache);
+		rc = mnt_context_apply_tab(cxt, cxt->mtab);
+		if (rc)
+			goto err;
+	}
+	return 0;
+
+errnomem:
+	rc = ENOMEM;
+err:
+	DBG(CXT, mnt_debug_h(cxt, "failed to found entry in fstab/mtab"));
+	return rc;
+}
+
+static int mnt_context_subst_optstr(mnt_context *cxt)
+{
+	int rc = 0;
+	char *o, *o0;
+	char *val = NULL;
+	size_t valsz = 0;
+
+	if (!cxt || !cxt->fs)
+		return -EINVAL;
+
+	o0 = o = (char *) mnt_fs_get_optstr(cxt->fs);
+	if (!o)
+		return 0;
+
+	if (!mnt_optstr_get_option(o, "uid", &val, &valsz) && val &&
+	    !strncmp(val, "useruid", 7)) {
+		char id[40];
+
+		snprintf(id, sizeof(id), "%u", getuid());
+		rc = mnt_optstr_set_option(&o, "uid", id);
+		if (rc)
+			return rc;
+	}
+
+	val = NULL, valsz = 0;
+
+	if (!mnt_optstr_get_option(o, "gid", &val, &valsz) && val &&
+	    !strncmp(val, "usergid", 7)) {
+		char id[40];
+
+		snprintf(id, sizeof(id), "%u", getgid());
+		rc = mnt_optstr_set_option(&o, "gid", id);
+		if (rc)
+			return rc;
+	}
+
+	if (o != o0)
+		rc = mnt_fs_set_optstr(cxt->fs, o);
+
+	return rc;
+}
+
+static int mnt_context_check_permissions(mnt_context *cxt)
+{
+	return 0; /* TODO */
+}
+
+static int mnt_context_prepare_srcpath(mnt_context *cxt)
+{
+	const char *path;
+	mnt_cache *cache;
+	const char *t, *v, *src;
+	int rc = 0;
+
+	if (!cxt || !cxt->fs)
+		return -EINVAL;
+
+	src = mnt_fs_get_source(cxt->fs);
+
+	/* ignore filesystems without a real source */
+	if (!src || (cxt->fs->flags & (MNT_FS_PSEUDO | MNT_FS_NET)))
+		return 0;
+
+	DBG(CXT, mnt_debug_h(cxt, "preparing srcpath '%s'", src));
+
+	cache = mnt_context_get_cache(cxt);
+
+	if (!mnt_fs_get_tag(cxt->fs, &t, &v)) {
+		/*
+		 * Source is TAG (evaluate)
+		 */
+		if (cache)
+			path = mnt_resolve_tag(t, v, cache);
+
+		rc = path ? mnt_fs_set_source(cxt->fs, path) : -EINVAL;
+	} else {
+		/*
+		 * Source is PATH (canonicalize)
+		 */
+		if (cache) {
+			path = mnt_resolve_path(src, cache);
+			if (strcmp(path, src))
+				rc = mnt_fs_set_source(cxt->fs, path);
+		} else
+			path = src;
+	}
+
+	if (rc) {
+		DBG(CXT, mnt_debug_h(cxt, "failed to prepare srcpath"));
+		return rc;
+	}
+
+	/*
+	 * Initialize loop device
+	 */
+	if (mnt_context_is_loop(cxt) &&
+	    !(cxt->mountflags & (MS_BIND | MS_MOVE |
+			         MS_PROPAGATION | MS_REMOUNT))) {
+		; /* TODO */
+	}
+
+	DBG(CXT, mnt_debug_h(cxt, "final srcpath '%s'", path));
+	return 0;
+}
+
+static int mnt_context_detect_fstype(mnt_context *cxt)
+{
+	return 0; /* TODO */
+}
+
+/**
+ * mnt_context_prepare_mount:
+ * @cxt: mount context
+ *
+ * This function:
+ *	- read information from fstab (if necessary)
+ *	- cleanup mount options
+ *	- check premissions
+ *	- prepare device (e.g. loop device)
+ *	- detect FS type (if necessary)
+ *	- generate mount flags and mount data (if not set yet)
+ *	- prepare for mtab update (if necessary)
+ *
+ * It's strongly recommended to use this function before mnt_context_mount_fs().
+ *
+ * Returns: 0 on success, and negative number in case of error.
+ */
+int mnt_context_prepare_mount(mnt_context *cxt)
+{
+	int rc = 0;
+
+	if (!cxt)
+		return -EINVAL;
+	if (!cxt->spec && !(cxt->fs && (mnt_fs_get_source(cxt->fs) ||
+			                mnt_fs_get_target(cxt->fs))))
+		return -EINVAL;
+
+	rc = mnt_context_apply_fstab(cxt);
+	if (rc)
+		goto err;
+
+	/* prepare mount flags */
+	{
+		unsigned long fl = 0;
+
+		rc = mnt_context_get_mountflags(cxt, &fl);
+		if (rc)
+			return rc;
+		cxt->mountflags = fl;
+
+		fl = 0;
+		rc = mnt_context_get_userspace_mountflags(cxt, &fl);
+		if (rc)
+			return rc;
+		cxt->user_mountflags = fl;
+
+		cxt->flags |= MNT_FL_MOUNTFLAGS_MERGED;
+	}
+
+	rc = mnt_context_subst_optstr(cxt);
+	if (rc)
+		goto err;
+
+	rc = mnt_context_check_permissions(cxt);
+	if (rc)
+		goto err;
+
+	rc = mnt_context_prepare_srcpath(cxt);
+	if (rc)
+		goto err;
+
+	rc = mnt_context_detect_fstype(cxt);
+	if (rc)
+		goto err;
+
+
+	/* TODO: prepare mtab update */
+
+	DBG(CXT, mnt_debug_h(cxt, "sucessfully prepared"));
+	return 0;
+err:
+	DBG(CXT, mnt_debug_h(cxt, "prepare failed"));
+	return rc;
+}
+
+int mnt_context_mount_fs(mnt_context *cxt)
+{
+	if (!cxt)
+		return -EINVAL;
+
+	DBG(CXT, mnt_debug_h(cxt, "mounting:"));
+	DBG(CXT, mnt_fs_print_debug(cxt->fs, stderr));
+	DBG(CXT, mnt_debug_h(cxt, "mountflags: 0x%lx", cxt->mountflags));
+
+	return 0;
+}
+
+#ifdef TEST_PROGRAM
+
+int test_mount(struct mtest *ts, int argc, char *argv[])
+{
+	int idx = 1, rc = 0;
+	mnt_context *cxt;
+
+	if (argc < 2)
+		return -EINVAL;
+
+	cxt = mnt_new_context();
+	if (!cxt)
+		return -ENOMEM;
+
+	if (!strcmp(argv[idx], "-o")) {
+		mnt_context_set_optstr(cxt, argv[idx + 1]);
+		idx += 2;
+	}
+	if (!strcmp(argv[idx], "-t")) {
+		/* TODO: use mnt_context_set_fstype_pattern() */
+		mnt_context_set_fstype(cxt, argv[idx + 1]);
+		idx += 2;
+	}
+
+	if (argc == idx + 1)
+		/* mount <spec> */
+		mnt_context_set_spec(cxt, argv[idx++]);
+
+	else if (argc == idx + 2) {
+		/* mount <device> <mountpoint> */
+		mnt_context_set_source(cxt, argv[idx++]);
+		mnt_context_set_target(cxt, argv[idx++]);
+	}
+
+	rc = mnt_context_prepare_mount(cxt);
+	if (rc)
+		fprintf(stderr, "failed to prepare mount\n");
+	else {
+		rc = mnt_context_mount_fs(cxt);
+		if (rc)
+			fprintf(stderr, "failed to mount\n");
+	}
+
+	mnt_free_context(cxt);
+	return rc;
+}
+
+int main(int argc, char *argv[])
+{
+	struct mtest tss[] = {
+	{ "--mount",    test_mount,        "[-o <opts>] [-t <type>] <spec> | <src> <target>" },
+	{ NULL }
+	};
+
+	return mnt_run_test(tss, argc, argv);
+}
+
+#endif /* TEST_PROGRAM */