[gparted] Stop relying on specific values of PED_PARTITION_* enum

[Curtis Gedak <gedakc src gnome org>]

commit 3b3d8e44b684041c776659f49198ae9d2e1acc6a
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Tue Nov 17 16:05:19 2015 +0000

    Stop relying on specific values of PED_PARTITION_* enum
    
    The expressions used in the call to Set() were comparing
    lp_partition->type to 0 for the type parameter and passing it as a bool
    for the inside_extended parameter.  Libparted lp_partition->type is
    actually an enumeration.  The code was only working because of the
    specific values assigned to the symbolic names, PED_PARTITION_NORMAL = 0
    and PED_PARTITION_EXTENDED is non-zero (true).
    
    Make the code use the symbolic names and not depend on the actual
    enumeration values, which should be considered changeable and private to
    libparted.

 src/GParted_Core.cc |   21 +++++++++++++++++++--
 1 files changed, 19 insertions(+), 2 deletions(-)
---
diff --git a/src/GParted_Core.cc b/src/GParted_Core.cc
index ba11b2e..59fa485 100644
--- a/src/GParted_Core.cc
+++ b/src/GParted_Core.cc
@@ -1244,6 +1244,20 @@ void GParted_Core::set_device_partitions( Device & device, PedDevice* lp_device,
                //Retrieve partition path
                Glib::ustring partition_path = get_partition_path( lp_partition );
 
+               // NOTE: lp_partition->type bit field
+               // lp_partition->type is a bit field using enumerated names for each bit.
+               // GParted is only interested in partitions with these single bits set:
+               // PED_PARTITION_NORMAL, PED_PARTITION_LOGICAL and PED_PARTITION_EXTENDED.
+               // Partitions, ranges of blocks, with other bits set representing free
+               // space and disk label meta-data, PED_PARTITION_FREESPACE and
+               // PED_PARTITION_METADATA bits respectively, are ignore and GParted
+               // creates it own unallocated partitions and accounts for partition
+               // tables.
+               // References:
+               // *   struct PedPartition and type PedPartitionType
+               //     https://www.gnu.org/software/parted/api/struct__PedPartition.html
+               // *   enum _PedPartitionType
+               //     http://git.savannah.gnu.org/cgit/parted.git/tree/include/parted/disk.in.h?id=v3.2#n45
                switch ( lp_partition ->type )
                {
                        case PED_PARTITION_NORMAL:
@@ -1272,13 +1286,14 @@ void GParted_Core::set_device_partitions( Device & device, PedDevice* lp_device,
                                partition_temp->Set( device .get_path(),
                                                     partition_path,
                                                     lp_partition->num,
-                                                    ( lp_partition->type == 0 ) ? TYPE_PRIMARY : 
TYPE_LOGICAL,
+                                                    ( lp_partition->type == PED_PARTITION_NORMAL ) ? 
TYPE_PRIMARY
+                                                                                                   : 
TYPE_LOGICAL,
                                                     false,
                                                     filesystem,
                                                     lp_partition->geom.start,
                                                     lp_partition->geom.end,
                                                     device.sector_size,
-                                                    lp_partition->type,
+                                                    ( lp_partition->type == PED_PARTITION_LOGICAL ),
                                                     partition_is_busy );
                                partition_temp->messages = detect_messages;
                                partition_temp->add_paths( pp_info.get_alternate_paths( 
partition_temp->get_path() ) );
@@ -1309,6 +1324,8 @@ void GParted_Core::set_device_partitions( Device & device, PedDevice* lp_device,
                                break ;
 
                        default:
+                               // Ignore libparted reported partitions with other type
+                               // bits set.
                                break;
                }