cmd: ubi: don't allow to rename a volume to a name that already exist

This commits add a check on the command ubi rename. This check avoids
to rename a volume to with a name that is already used on another ubi
volume. If two volumes has the same name, then the ubi device can't be
mounted anymore.
Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>

cmd/ubi.c

@@ -264,6 +264,11 @@ static int ubi_rename_vol(char *oldname, char *newname)
 		return ENODEV;
 	}
 
+	if (!ubi_check(newname)) {
+		printf("%s: volume %s already exist\n", __func__, newname);
+		return EINVAL;
+	}
+
 	printf("Rename UBI volume %s to %s\n", oldname, newname);
 
 	if (ubi->ro_mode) {