[gparted] Simplify ext2::get_filesystem_support() with regard ext4 support (#794253)

[Curtis Gedak <gedakc src gnome org>]

commit de6e70d933286f3c65187470c9852fb6d8a60a7d
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Thu Mar 8 11:29:10 2018 +0000

    Simplify ext2::get_filesystem_support() with regard ext4 support (#794253)
    
    E2fsprogs 1.41.0 (from 10 July 2008) first included ext4 support [1].
    As RHEL / CentOS 6 is now the oldest supported distribution, and that
    includes e2fsprogs 1.41.12 (from 22 August 2009) [2] all the e2fs
    programs support ext4 so it is no longer necessary to also depend on
    finding mkfs.ext4 before enabling each supported capability for ext4.
    This makes the ext2::get_filesystem_support() look like all the others
    in which each supported capability only depends on the presence of the
    relevant file system specific command.
    
    [1] Release notes for the e2fsprogs package / E2fsprogs 1.41.0
        http://e2fsprogs.sourceforge.net/e2fsprogs-release.html#1.41.0
    
    [2] pkgs.org > CentOS 6 > CentOS x86_64 > e2fsprogs
        https://centos.pkgs.org/6/centos-x86_64/e2fsprogs-1.41.12-23.el6.x86_64.rpm.html
    
    Bug 794253 - Desupport RHEL / CentOS 5 and raise minimum required
                 versions to glibmm 2.14.0 and gtkmm 2.16.0

 src/ext2.cc |  106 +++++++++++++++++++++++++++++------------------------------
 1 files changed, 52 insertions(+), 54 deletions(-)
---
diff --git a/src/ext2.cc b/src/ext2.cc
index 9b1ca83..7bd191f 100644
--- a/src/ext2.cc
+++ b/src/ext2.cc
@@ -32,17 +32,14 @@ FS ext2::get_filesystem_support()
 
        fs .busy = FS::GPARTED ;
 
-       // Only enable functionality if the relevant mkfs.extX command is found to ensure
-       // that the version of e2fsprogs is new enough to support ext4.  Applying to
-       // ext2/3 is OK as relevant mkfs.ext2/3 commands exist.
        mkfs_cmd = "mkfs." + Utils::get_filesystem_string( specific_type );
+       bool have_64bit_feature = false;
        if ( ! Glib::find_program_in_path( mkfs_cmd ).empty() )
        {
                fs .create = FS::EXTERNAL ;
                fs .create_with_label = FS::EXTERNAL ;
 
                // Determine mkfs.ext4 version specific capabilities.
-               bool have_64bit_feature = false;
                force_auto_64bit = false;
                if ( specific_type == FS_EXT4 )
                {
@@ -76,68 +73,69 @@ FS ext2::get_filesystem_support()
                                                   || ( mke4fs_major_ver == 1 && mke4fs_minor_ver >= 42 );
                        }
                }
+       }
 
-               if ( ! Glib::find_program_in_path( "dumpe2fs").empty() )
-                       fs .read = FS::EXTERNAL ;
+       if ( ! Glib::find_program_in_path( "dumpe2fs").empty() )
+       {
+               fs.read = FS::EXTERNAL;
+               fs.online_read = FS::EXTERNAL;
+       }
 
-               if ( ! Glib::find_program_in_path( "tune2fs" ).empty() )
-               {
-                       fs .read_uuid = FS::EXTERNAL ;
-                       fs .write_uuid = FS::EXTERNAL ;
-               }
+       if ( ! Glib::find_program_in_path( "tune2fs" ).empty() )
+       {
+               fs.read_uuid = FS::EXTERNAL;
+               fs.write_uuid = FS::EXTERNAL;
+       }
 
-               if ( ! Glib::find_program_in_path( "e2label" ).empty() )
-               {
-                       fs .read_label = FS::EXTERNAL ;
-                       fs .write_label = FS::EXTERNAL ;
-               }
+       if ( ! Glib::find_program_in_path( "e2label" ).empty() )
+       {
+               fs.read_label = FS::EXTERNAL;
+               fs.write_label = FS::EXTERNAL;
+       }
 
-               if ( ! Glib::find_program_in_path( "e2fsck" ).empty() )
-                       fs .check = FS::EXTERNAL ;
-       
-               if ( ! Glib::find_program_in_path( "resize2fs" ).empty() )
-               {
-                       fs .grow = FS::EXTERNAL ;
+       if ( ! Glib::find_program_in_path( "e2fsck" ).empty() )
+               fs.check = FS::EXTERNAL;
 
-                       if ( fs .read ) //needed to determine a min file system size..
-                               fs .shrink = FS::EXTERNAL ;
-               }
+       if ( ! Glib::find_program_in_path( "resize2fs" ).empty() )
+       {
+               fs.grow = FS::EXTERNAL;
 
-               if ( fs .check )
-               {
-                       fs.copy = fs.move = FS::GPARTED ;
+               if ( fs.read )  // Needed to determine a min file system size..
+                       fs.shrink = FS::EXTERNAL;
+       }
 
-                       //If supported, use e2image to copy/move the file system as it
-                       //  only copies used blocks, skipping unused blocks.  This is more
-                       //  efficient than copying all blocks used by GParted's internal
-                       //  method.
-                       if ( ! Glib::find_program_in_path( "e2image" ).empty() )
-                       {
-                               Utils::execute_command( "e2image", output, error, true ) ;
-                               if ( Utils::regexp_label( error, "(-o src_offset)" ) == "-o src_offset" )
-                                       fs.copy = fs.move = FS::EXTERNAL ;
-                       }
+       if ( fs.check )
+       {
+               fs.copy = fs.move = FS::GPARTED;
+
+               // If supported, use e2image to copy/move the file system as it only
+               // copies used blocks, skipping unused blocks.  This is more efficient
+               // than copying all blocks used by GParted's internal method.
+               if ( ! Glib::find_program_in_path( "e2image" ).empty() )
+               {
+                       Utils::execute_command( "e2image", output, error, true );
+                       if ( Utils::regexp_label( error, "(-o src_offset)" ) == "-o src_offset" )
+                               fs.copy = fs.move = FS::EXTERNAL;
                }
+       }
 
-               fs .online_read = FS::EXTERNAL ;
 #ifdef ENABLE_ONLINE_RESIZE
-               if ( specific_type != FS_EXT2 && Utils::kernel_version_at_least( 3, 6, 0 ) )
-                       fs .online_grow = fs .grow ;
+       if ( specific_type != FS_EXT2 && Utils::kernel_version_at_least( 3, 6, 0 ) )
+               fs.online_grow = fs.grow;
 #endif
 
-               // Maximum size of an ext2/3/4 volume is 2^32 - 1 blocks, except for ext4
-               // with 64bit feature.  That is just under 16 TiB with a 4K block size.
-               // *   Ext4 Disk Layout, Blocks
-               //     https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#Blocks
-               // FIXME: Rounding down to whole MiB here should not be necessary.  The
-               // Copy, New and Resize/Move dialogs should limit FS correctly without
-               // this.  See bug #766910 comment #12 onwards for further discussion.
-               //     https://bugzilla.gnome.org/show_bug.cgi?id=766910#c12
-               if ( specific_type == FS_EXT2                             ||
-                    specific_type == FS_EXT3                             ||
-                    ( specific_type == FS_EXT4 && ! have_64bit_feature )    )
-                       fs_limits.max_size = Utils::floor_size( 16 * TEBIBYTE - 4 * KIBIBYTE, MEBIBYTE );
-       }
+       // Maximum size of an ext2/3/4 volume is 2^32 - 1 blocks, except for ext4 with
+       // 64bit feature.  That is just under 16 TiB with a 4K block size.
+       // *   Ext4 Disk Layout, Blocks
+       //     https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#Blocks
+       // FIXME: Rounding down to whole MiB here should not be necessary.  The Copy, New
+       // and Resize/Move dialogs should limit FS correctly without this.  See bug
+       // #766910 comment #12 onwards for further discussion.
+       //     https://bugzilla.gnome.org/show_bug.cgi?id=766910#c12
+       if ( specific_type == FS_EXT2                             ||
+            specific_type == FS_EXT3                             ||
+            ( specific_type == FS_EXT4 && ! have_64bit_feature )    )
+               fs_limits.max_size = Utils::floor_size( 16 * TEBIBYTE - 4 * KIBIBYTE, MEBIBYTE );
 
        return fs ;
 }