[gparted] Also use libparted to probe for encrypted file systems (#148)

[Curtis Gedak <gedakc src gnome org>]

commit 1adb28b0c4fb8299d9c9f123d179d9e5a776f4a4
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Mon Mar 29 22:13:22 2021 +0100

    Also use libparted to probe for encrypted file systems (#148)
    
    Even though blkid is considered mandatory [1] GParted should still
    perform reasonably when blkid is not available, provided that is not too
    onerous a task.  Also use libparted file system identification inside
    encryption mappings.
    
    [1] 749a2495716a82a7287fad943109b6cfb927245c
        Document blkid command as a mandatory requirement (#753436)
    
    Closes 148 - Encrypted file systems are no longer recognised

 src/GParted_Core.cc | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)
---
diff --git a/src/GParted_Core.cc b/src/GParted_Core.cc
index 155c7d40..1a4b2ae6 100644
--- a/src/GParted_Core.cc
+++ b/src/GParted_Core.cc
@@ -1082,8 +1082,19 @@ FSType GParted_Core::detect_filesystem_in_encryption_mapping(const Glib::ustring
        PedDevice *lp_device = NULL;
        if (get_device(path, lp_device))
        {
-               fstype = detect_filesystem(lp_device, NULL, messages);
+               // Run libparted partition table and file system identification.  Only use
+               // (get the first partition) if it's a "loop" table; because GParted only
+               // supports one block device to one encryption mapping to one file system.
                PedDisk *lp_disk = NULL;
+               PedPartition *lp_partition = NULL;
+               if (get_disk(lp_device, lp_disk) && lp_disk->type && lp_disk->type->name &&
+                   strcmp(lp_disk->type->name, "loop") == 0                               )
+               {
+                       lp_partition = ped_disk_next_partition(lp_disk, NULL);
+               }
+
+               fstype = detect_filesystem(lp_device, lp_partition, messages);
+
                destroy_device_and_disk(lp_device, lp_disk);
        }