Avoid reading trailing junk for a reiser4 label (#689318)

For a reiser4 file system with exactly the maximum size 16 character
label, debugfs.reiser4 may include junk at the end of the label it
prints.  (It reads the label into a 16 character array and prints it as
a string, but there isn't a nul terminating character).

    # mkfs.reiser4 --yes --label abcdefghij123456 /dev/sda13
    # debugfs.reiser4 /dev/sda13 2> /dev/null | grep label:
    label:          abcdefghij123456!

Trim the read label to at most 16 characters.

Bug #689318 - filesystem type specific support for partition name
              maximum length

src/reiser4.cc

@@ -97,6 +97,9 @@ void reiser4::read_label( Partition & partition )
 	if ( ! Utils::execute_command( "debugfs.reiser4 " + partition .get_path(), output, error, true ) )
 	{
 		Glib::ustring label = Utils::regexp_label( output, "^label:[[:blank:]]*(.*)$" ) ;
+		//Avoid reading any trailing junk after the label
+		if ( label .length() > 16 )
+			label .resize( 16 ) ;
 		if ( label != "<none>" )
 			partition .set_label( label ) ;
 		else