[gparted] Fix ntfs resize progress tracker matching spurious text (#760709)

[Curtis Gedak <gedakc src gnome org>]

commit af0ed90d497d045482f480108ce3ef42cda47359
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Mon Jan 18 15:59:51 2016 +0000

    Fix ntfs resize progress tracker matching spurious text (#760709)
    
    When the ntfs resize operation had almost completed, percentage complete
    was >= 99.9%, the progress tracker was passing 0.04 (4%) to the progress
    bar.  After reading the next chunk of output from the ntfsresize command
    the last line contained this text:
        "  4)  set the bootable flag for the partit"
    
    End of the ntfsresize command output for context:
        Relocating needed data ...
        100.00 percent completed
        Updating $BadClust file ...
        Updating $Bitmap file ...
        Updating Boot record ...
        Syncing device ...
        Successfully resized NTFS on device '/dev/sdd4'.
        You can go on to shrink the device for example with Linux fdisk.
        IMPORTANT: When recreating the partition, make sure that you
          1)  create it at the same disk sector (use sector as the unit!)
          2)  create it with the same partition type (usually 7, HPFS/NTFS)
          3)  do not make it smaller than the new NTFS filesystem size
          4)  set the bootable flag for the partition if it existed before
        Otherwise you won't be able to access NTFS or can't boot from the disk!
        If you make a mistake and don't have a partition table backup then you
        can recover the partition table by TestDisk or Parted's rescue mode.
    
    This was occurring because *scanf() can't actually report failure to
    match fixed text after conversion of the last variable.  See code
    comment in ntfs::resize_progress() for more details.  Fix by using
    .find() instead to match the required "percent completed" explicit text
    of the progress information when it appears on the last line.
    
    Bug 760709 - Add progress bars to XFS and EXT2/3/4 file system specific
                 copy methods

 src/ntfs.cc |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)
---
diff --git a/src/ntfs.cc b/src/ntfs.cc
index d701eec..979f6d9 100644
--- a/src/ntfs.cc
+++ b/src/ntfs.cc
@@ -270,8 +270,17 @@ void ntfs::resize_progress( OperationDetail *operationdetail )
        ProgressBar & progressbar = operationdetail->get_progressbar();
        Glib::ustring line = Utils::last_line( output );
        // Text progress on the LAST LINE looks like " 15.24 percent completed"
+       // NOTE:
+       // Specifying text to match following the last converted variable in *scanf() is
+       // ineffective because it reports the number of successfully converted variables
+       // and has no way to indicate following text didn't match.  Specifically:
+       //     sscanf( "%f percent completed", &percent )
+       // will return 1 after successfully converting percent variable as 4 given this
+       // line from the important information at the end of the ntfsresize output:
+       //     "  4)  set the bootable flag for the partit"
+       // Definitely not progress information.
        float percent;
-       if ( sscanf( line.c_str(), "%f percent completed", &percent ) == 1 )
+       if ( line.find( "percent completed" ) != line.npos && sscanf( line.c_str(), "%f", &percent ) == 1 )
        {
                if ( ! progressbar.running() )
                        progressbar.start( 100.0 );