[gparted] Remove prohibited characters from FAT16/32 labels (#755608)

[Curtis Gedak <gedakc src gnome org>]

commit 584137b32b4deed2c20022628baaee6b38570fa5
Author: Albert Young <youngac3 gmail com>
Date:   Tue Sep 29 23:02:43 2015 -0500

    Remove prohibited characters from FAT16/32 labels (#755608)
    
    GParted waits forever when attempting to set a FAT16/32 file system
    label which contains prohibited characters [1][2].  This is because
    mlabel asks a question and is waiting for input.  Force cancelling the
    operation doesn't work either as GParted sends signal 2 (interrupt i.e.
    [Ctrl-C]) but mtools commands specifically ignores this and a number of
    other signals.  Have to kill mlabel with signal 9 (kill) to regain
    control of GParted.
    
    Mlabel command with prohibited characters in the label:
    
        # export MTOOLS_SKIP_CHECK=1
        # mlabel ::"MYLABEL/   " -i /dev/sdb10
        Long file name "MYLABEL/   " contains illegal character(s).
        a)utorename A)utorename-all r)ename R)ename-all
        s)kip S)kip-all q)uit (aArRsSq):
    
    Remove prohibited characters from FAT16/32 file systems labels when
    creating and labelling them.  Also upper case the label to meet label
    requirements [1][2].  This silently corrects the label and the actual
    label applied will be displayed when GParted refreshes after applying
    the operation.
    
    [1] Microsoft TechNet: Label
        https://technet.microsoft.com/en-us/library/bb490925.aspx
    
    [2] Replicated in Wikikedia: label (command)
        https://en.wikipedia.org/wiki/Label_%28command%29
    
    Bug 755608 - Labeling fat16/fat32 partitions hangs if certain characters
                 included in label

 include/fat16.h |    2 +-
 src/fat16.cc    |   24 +++++++++++++++++++-----
 2 files changed, 20 insertions(+), 6 deletions(-)
---
diff --git a/include/fat16.h b/include/fat16.h
index 4285cd3..2c5db2d 100644
--- a/include/fat16.h
+++ b/include/fat16.h
@@ -43,7 +43,7 @@ public:
 
 private:
        static const Glib::ustring Change_UUID_Warning [] ;
-       const Glib::ustring pad_label( const Glib::ustring &label ) const ;
+       const Glib::ustring sanitize_label( const Glib::ustring & label ) const;
 };
 
 } //GParted
diff --git a/src/fat16.cc b/src/fat16.cc
index e203422..7f449c0 100644
--- a/src/fat16.cc
+++ b/src/fat16.cc
@@ -193,7 +193,8 @@ bool fat16::write_label( const Partition & partition, OperationDetail & operatio
        if ( partition.get_filesystem_label().empty() )
                cmd = "mlabel -c :: -i " + partition.get_path();
        else
-               cmd = "mlabel ::\"" + pad_label( partition.get_filesystem_label() ) + "\" -i " + 
partition.get_path();
+               cmd = "mlabel ::\"" + sanitize_label( partition.get_filesystem_label() ) + "\" -i "
+                   + partition.get_path();
 
        return ! execute_command( cmd, operationdetail, EXEC_CHECK_STATUS );
 }
@@ -229,7 +230,7 @@ bool fat16::create( const Partition & new_partition, OperationDetail & operation
 {
        Glib::ustring fat_size = specific_type == FS_FAT16 ? "16" : "32" ;
        return ! execute_command( create_cmd + " -F" + fat_size + " -v -I -n \"" +
-                                 pad_label( new_partition.get_filesystem_label() ) + "\" " +
+                                 sanitize_label( new_partition.get_filesystem_label() ) + "\" " +
                                  new_partition.get_path(),
                                  operationdetail,
                                  EXEC_CHECK_STATUS|EXEC_CANCEL_SAFE );
@@ -246,11 +247,24 @@ bool fat16::check_repair( const Partition & partition, OperationDetail & operati
 
 //Private methods
 
-//Pad fat label with spaces to prevent mlabel writing corrupted labels.  See bug #700228
-const Glib::ustring fat16::pad_label( const Glib::ustring &label ) const
+const Glib::ustring fat16::sanitize_label( const Glib::ustring &label ) const
 {
-       Glib::ustring new_label = label ;
+       Glib::ustring uppercase_label = label.uppercase();
+       Glib::ustring new_label;
+
+       // Copy uppercase label excluding prohibited characters.
+       // [1] Microsoft TechNet: Label
+       //     https://technet.microsoft.com/en-us/library/bb490925.aspx
+       // [2] Replicated in Wikikedia: label (command)
+       //     https://en.wikipedia.org/wiki/Label_%28command%29
+       Glib::ustring prohibited_chars( "*?.,;:/\\|+=<>[]" );
+       for ( unsigned int i = 0 ; i < label.size() ; i ++ )
+               if ( prohibited_chars.find( uppercase_label[i] ) == Glib::ustring::npos )
+                       new_label.push_back( uppercase_label[i] );
+
+       // Pad with spaces to prevent mlabel writing corrupted labels.  See bug #700228.
        new_label .resize( Utils::get_filesystem_label_maxlength( specific_type ), ' ' ) ;
+
        return new_label ;
 }