mount: add support for mixed usage of SPECes

This patch improves a way how the mount works with SPECes (devname,
LABEL or UUID) and nodes (mountpoints) from command line.

The patch adds support for mixed usage of SPECes -- it means on
command line is different SPEC than in the /etc/fstab file. For
example:

command line:
   mount LABEL=foo
fstab:
   UID=915b048a-998d-4ee5-9e6b-7fcaaf34d3c5 /mnt/foo auto default

The mount command doesn't strictly require same SPEC on command line
and in fstab anymore. You can be more creative and mix UUID, LABEL
or device name.

This implementation is more effective that convert *all* entries from
/etc/fstab to a real devnames.

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

1 files changed, 102 insertions, 51 deletions

diff --git a/mount/mount.c b/mount/mount.c
index 3ebf4db76..d9a4b81aa 100644
--- a/mount/mount.c
+++ b/mount/mount.c
@@ -1645,14 +1645,91 @@ usage (FILE *fp, int n) {
 	exit (n);
 }
 
+/* returns mount entry from fstab */
+static struct mntentchn *
+getfs(const char *spec, const char *uuid, const char *label)
+{
+	struct mntentchn *mc = NULL;
+	const char *devname = NULL;
+
+	/*
+	 * A) 99% of all cases, the spec on cmdline matches
+	 *    with spec in fstab
+	 */
+	if (uuid)
+		mc = getfs_by_uuid(uuid);
+	else if (label)
+		mc = getfs_by_label(label);
+	else {
+		mc = getfs_by_spec(spec);
+
+		if (!mc)
+			mc = getfs_by_dir(spec);
+	}
+	if (mc)
+		return mc;
+
+	/*
+	 * B) UUID or LABEL on cmdline, but devname in fstab
+	 */
+	if (uuid)
+		devname = fsprobe_get_devname_by_uuid(uuid);
+	else if (label)
+		devname = fsprobe_get_devname_by_label(label);
+	else
+		devname = fsprobe_get_devname(spec);
+
+	if (devname)
+		mc = getfs_by_devname(devname);
+
+	/*
+	 * C) mixed
+	 */
+	if (!mc && devname) {
+		const char *id = NULL;
+
+		if (!label && (!spec || strncmp(spec, "LABEL=", 6))) {
+			id = fsprobe_get_label_by_devname(devname);
+			if (id)
+				mc = getfs_by_label(id);
+		}
+		if (!mc && !uuid && (!spec || strncmp(spec, "UUID=", 5))) {
+			id = fsprobe_get_uuid_by_devname(devname);
+			if (id)
+				mc = getfs_by_uuid(id);
+		}
+		my_free(id);
+
+		if (mc) {
+			/* use real device name to avoid repetitional
+			 * conversion from LABEL/UUID to devname
+			 */
+			my_free(mc->m.mnt_fsname);
+			mc->m.mnt_fsname = xstrdup(devname);
+		}
+	}
+
+	/*
+	 * D) remount -- try /etc/mtab
+	 *    Earlier mtab was tried first, but this would sometimes try the
+	 *    wrong mount in case mtab had the root device entry wrong.
+	 */
+	if (!mc)
+		mc = getmntfile (devname ? devname : spec);
+
+	if (devname)
+		my_free(devname);
+	return mc;
+}
+
 char *progname;
 
 int
 main(int argc, char *argv[]) {
 	int c, result = 0, specseen;
 	char *options = NULL, *test_opts = NULL, *node;
-	const char *spec;
-	char *volumelabel = NULL;
+	const char *spec = NULL;
+	char *label = NULL;
 	char *uuid = NULL;
 	char *types = NULL;
 	char *p;
@@ -1705,7 +1782,7 @@ main(int argc, char *argv[]) {
 			list_with_volumelabel = 1;
 			break;
 		case 'L':
-			volumelabel = optarg;
+			label = optarg;
 			break;
 		case 'n':		/* do not write /etc/mtab */
 			++nomtab;
@@ -1825,7 +1902,7 @@ main(int argc, char *argv[]) {
 	argc -= optind;
 	argv += optind;
 
-	specseen = (uuid || volumelabel) ? 1 : 0; 	/* yes, .. i know */
+	specseen = (uuid || label) ? 1 : 0;	/* yes, .. i know */
 
 	if (argc+specseen == 0 && !mount_all) {
 		if (options || mounttype)
@@ -1847,19 +1924,6 @@ main(int argc, char *argv[]) {
 		create_mtab ();
 	}
 
-	if (specseen) {
-		if (uuid)
-			spec = fsprobe_get_devname_by_uuid(uuid);
-		else
-			spec = fsprobe_get_devname_by_label(volumelabel);
-
-		if (!spec)
-			die (EX_USAGE, _("mount: no such partition found"));
-		if (verbose)
-			printf(_("mount: mounting %s\n"), spec);
-	} else
-		spec = NULL;		/* just for gcc */
-
 	switch (argc+specseen) {
 	case 0:
 		/* mount -a */
@@ -1869,39 +1933,20 @@ main(int argc, char *argv[]) {
 		break;
 
 	case 1:
-		/* mount [-nfrvw] [-o options] special | node */
+		/* mount [-nfrvw] [-o options] special | node
+		 * (/etc/fstab is necessary)
+		 */
 		if (types != NULL)
 			usage (stderr, EX_USAGE);
-		if (specseen) {
-			/* We know the device. Where shall we mount it? */
-			mc = (uuid ? getfs_by_uuid (uuid)
-			           : getfs_by_label (volumelabel));
-			if (mc == NULL)
-				mc = getfs_by_spec (spec);
-			if (mc == NULL)
-				die (EX_USAGE,
-				     _("mount: cannot find %s in %s"),
-				     spec, _PATH_FSTAB);
-			mc->m.mnt_fsname = spec;
-		} else {
-			/* Try to find the other pathname in fstab.  */
-			spec = canonicalize (*argv);
-			if ((mc = getfs_by_spec (spec)) == NULL &&
-			    (mc = getfs_by_dir (spec)) == NULL &&
-			    /* Try noncanonical name in fstab
-			       perhaps /dev/cdrom or /dos is a symlink */
-			    (mc = getfs_by_spec (*argv)) == NULL &&
-			    (mc = getfs_by_dir (*argv)) == NULL &&
-			    /* Try mtab - maybe this was a remount */
-			    (mc = getmntfile (spec)) == NULL)
-				die (EX_USAGE,
-				     _("mount: can't find %s in %s or %s"),
-				     spec, _PATH_FSTAB, MOUNTED);
-			/* Earlier mtab was tried first, but this would
-			   sometimes try the wrong mount in case mtab had
-			   the root device entry wrong. */
-
-			my_free(spec);
+
+		mc = getfs(*argv, uuid, label);
+		if (!mc) {
+			if (uuid || label)
+				die (EX_USAGE, _("mount: no such partition found"));
+
+			die (EX_USAGE,
+			     _("mount: can't find %s in %s or %s"),
+			     spec, _PATH_FSTAB, MOUNTED);
 		}
 
 		result = mount_one (xstrdup (mc->m.mnt_fsname),
@@ -1911,17 +1956,23 @@ main(int argc, char *argv[]) {
 		break;
 
 	case 2:
-		/* mount [-nfrvw] [-t vfstype] [-o options] special node */
+		/* mount special node  (/etc/fstab is not necessary) */
 		if (specseen) {
-			/* we have spec already */
+			/* mount -L label node   (or -U uuid) */
+			spec = uuid ?	fsprobe_get_devname_by_uuid(uuid) :
+					fsprobe_get_devname_by_label(label);
 			node = argv[0];
 		} else {
+			/* mount special node */
 			spec = argv[0];
 			node = argv[1];
 		}
+		if (!spec)
+			die (EX_USAGE, _("mount: no such partition found"));
+
 		result = mount_one (spec, node, types, NULL, options, 0, 0);
 		break;
-      
+
 	default:
 		usage (stderr, EX_USAGE);
 	}