[gparted] Remove use of wipefs to clear file system signatures (#688882)

[Curtis Gedak <gedakc src gnome org>]

commit 2b7e4694737230fde0c9b841e03e0f3eb3699285
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Sat Mar 23 15:09:26 2013 +0000

    Remove use of wipefs to clear file system signatures (#688882)
    
    The wipefs command has the following significant limitations which were
    worked around in previous commits:
    
    1)  Wasn't available in the earliest distributions supported by GParted;
    
    2)  Had to be called 3 times to erase vfat (fat16/32) signatures in all
        but the most recent versions.
    
    This meant we had all the code to clear file system signatures without
    using the wipefs command as well as extra complexity of using wipefs
    too.  So just remove use of the wipefs command.
    
    Bug #688882 - Improve clearing of file system signatures

 include/GParted_Core.h |    2 -
 src/GParted_Core.cc    |   60 ++++++++----------------------------------------
 2 files changed, 10 insertions(+), 52 deletions(-)
---
diff --git a/include/GParted_Core.h b/include/GParted_Core.h
index 9892a65..da4b0c0 100644
--- a/include/GParted_Core.h
+++ b/include/GParted_Core.h
@@ -179,8 +179,6 @@ private:
                                   OperationDetail & operationdetail ) ;
        FileSystem* set_proper_filesystem( const FILESYSTEM & filesystem ) ;
        bool erase_filesystem_signatures( const Partition & partition, OperationDetail & operationdetail ) ;
-       bool wipe_filesystem_signatures( const Glib::ustring & device_path,
-                                        OperationDetail & operationdetail, Glib::ustring & output ) ;
        bool update_bootsector( const Partition & partition, OperationDetail & operationdetail ) ;
 
        //general..     
diff --git a/src/GParted_Core.cc b/src/GParted_Core.cc
index c44088c..ce25e22 100644
--- a/src/GParted_Core.cc
+++ b/src/GParted_Core.cc
@@ -3130,31 +3130,11 @@ bool GParted_Core::filesystem_resize_disallowed( const Partition & partition )
 
 bool GParted_Core::erase_filesystem_signatures( const Partition & partition, OperationDetail & 
operationdetail )
 {
-       bool overall_success = false ;
+       bool overall_success ;
        operationdetail .add_child( OperationDetail(
                        String::ucompose( _("clear old file system signatures in %1"),
                                          partition .get_path() ) ) ) ;
 
-       if ( ! Glib::find_program_in_path( "wipefs" ) .empty() )
-       {
-               Glib::ustring output ;
-               OperationDetail & od = operationdetail .get_last_child() ;
-               bool wipefs_success = wipe_filesystem_signatures( partition .get_path(), od, output ) ;
-
-               //Before util-linux 2.21.0, released Feb 2012, wipefs only erased 1 of
-               //  the 3 vfat (fat16/fat32) signatures each time it was called.  If only
-               //  one vfat signature was wiped, found "(vfat)" only once in the output,
-               //  execute wipefs 2 more time.
-               Glib::ustring::size_type p1 = output .find( "(vfat)" ) ;
-               if (    p1 != Glib::ustring::npos
-                    && output .find( "(vfat)", p1+6 ) == Glib::ustring::npos )
-               {
-                       wipefs_success &= wipe_filesystem_signatures( partition .get_path(), od, output ) ;
-                       wipefs_success &= wipe_filesystem_signatures( partition .get_path(), od, output ) ;
-               }
-               overall_success = wipefs_success ;
-       }
-
        //Get device, disk & partition and open the device.  Allocate buffer and fill with
        //  zeros.  Buffer size is the greater of 4 KiB and the sector size.
        PedDevice* lp_device = NULL ;
@@ -3181,14 +3161,13 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition, Ope
        /*TO TRANSLATORS: looks like  wrote 68.00 KiB of zeros at byte offset 0 */
        const Glib::ustring wrote_zeros_msg = _("wrote %1 of zeros at byte offset %2") ;
 
-       if ( ! overall_success )
+       //Erase all file system primary super blocks including their signatures.
+       //  Overwrite the first 68 KiB with zeros (or larger if if the sector size is
+       //  larger than 4 KiB.  This covers the location all supported file super blocks
+       //  which range offset 0 for vfat, ntfs and xfs all the way up to offset 64 KiB
+       //  for btrfs, reiserfs and reiser4.  This is likely to also include future file
+       //  system super blocks too).
        {
-               //Wipefs either doesn't exist or reported an error clearing the file
-               //  system signatures.  Fall back to writing zeros over the first 68 KiB
-               //  of the partition to clear any super blocks and their signatures.  (May
-               //  be more if the block size is larger than 4 KiB.  File system super
-               //  blocks have a range of locations from offset 0 for vfat, ntfs and xfs
-               //  all the way up to offset 64 KiB for btrfs, reiserfs and reiser4).
                OperationDetail & od = operationdetail .get_last_child() ;
                od .add_child( OperationDetail( _("clear primary signatures") ) ) ;
 
@@ -3224,9 +3203,9 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition, Ope
                overall_success = zero_success ;
        }
 
-       //Erase any nilfs2 secondary super block to prevent erroneous detection by
-       //  libparted because wipefs didn't clear the signature in the secondary super
-       //  block.  Overwrite the last full 4 KiB block with zeros (or larger if the
+       //Also erase any nilfs2 secondary super block at the end of the partition to
+       //  prevent erroneous detection by libparted using the signature in the secondary
+       //  super block.  Overwrite the last full 4 KiB block with zeros (or larger if the
        //  sector size is larger and possibly earlier depending on the sector alignment).
        //  Ref: nilfs-utils-2.1.4/include/nilfs2_fs.h
        //  #define NILFS_SB2_OFFSET_BYTES(devsize) ((((devsize) >> 12) - 1) << 12)
@@ -3308,25 +3287,6 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition, Ope
        return overall_success ;
 }
 
-bool GParted_Core::wipe_filesystem_signatures( const Glib::ustring & path,
-                                               OperationDetail & operationdetail, Glib::ustring & output )
-{
-       bool success ;
-       Glib::ustring error ;
-       Glib::ustring command = "wipefs -a " + path ;
-
-       operationdetail .add_child( OperationDetail( command, STATUS_EXECUTE, FONT_BOLD_ITALIC ) ) ;
-       int exit_status = Utils::execute_command( command, output, error, true ) ;
-       if ( ! output .empty() )
-               operationdetail .get_last_child() .add_child( OperationDetail( output, STATUS_NONE, 
FONT_ITALIC ) ) ;
-       if ( ! error .empty() )
-               operationdetail .get_last_child() .add_child( OperationDetail( error, STATUS_NONE, 
FONT_ITALIC ) ) ;
-       success = ( 0 == exit_status ) ;
-       operationdetail .get_last_child() .set_status( success ? STATUS_SUCCES : STATUS_ERROR ) ;
-
-       return success ;
-}
-
 bool GParted_Core::update_bootsector( const Partition & partition, OperationDetail & operationdetail ) 
 {
        //only for ntfs atm...