virtualbox/cap: fix path comparison for extra disks in snapshots

When a VirtualBox VM has snapshots, the primary disk location may be under
the Snapshots subdirectory, causing path comparison with other disks to
fail. Update the comparison logic to also consider the parent directory
of the Snapshots folder, allowing existing extra disks to be found and
preventing attempts to recreate them that would result in VERR_ALREADY_EXISTS
errors.

Fixes #13352

Signed-off-by: GitHub Copilot <[email protected]>

Author: GitHub Copilot

plugins/providers/virtualbox/cap/configure_disks.rb

@@ -128,8 +128,24 @@ def self.handle_configure_disk(machine, disk, controller_name)
             # associated with the guest, since disk names are not unique
             # globally to VirtualBox.
             primary = storage_controllers.get_primary_attachment
+
+            # Determine candidate directories for the primary disk. When a VM
+            # has snapshots, VirtualBox may place snapshot differencing disks
+            # under a 'Snapshots' subdirectory while original disks live in the
+            # parent VM folder. For example:
+            #  - /.../test_default_xxx/data.vdi
+            #  - /.../test_default_xxx/Snapshots/{uuid}.vdi
+            # In that case, primary[:location] may point to the Snapshots path
+            # so we should also consider the parent directory when attempting
+            # to match existing extra disks by location.
+            primary_dir = File.dirname(primary[:location])
+            primary_dir_candidates = [primary_dir]
+            if File.basename(primary_dir) == "Snapshots"
+              primary_dir_candidates << File.dirname(primary_dir)
+            end
+
             existing_disk = machine.provider.driver.list_hdds.detect do |d|
-              File.dirname(d["Location"]) == File.dirname(primary[:location]) &&
+              primary_dir_candidates.include?(File.dirname(d["Location"])) &&
                 d["Disk Name"] == disk.name
             end