utils: add restore_windows_efi_bootloader

Add restore_windows_efi_bootloader to copy the EFI loader from
the filesystem in the restored system into the EFI partition.

This commit is preparatory work for the new native postinstall code.

src/utils/uefi.py

@@ -162,3 +162,34 @@ def copy_windows_efi_bootloader(disk, partition):
     finally:
         umount(mountpoint)
         umount(esp_mountpoint)
+
+
+def restore_windows_efi_bootloader(disk, partition):
+    device = get_partition_device(disk, partition)
+    mountpoint = device.replace('dev', 'mnt')
+    if not mount_mkdir(device, mountpoint):
+        raise OgError(f'Cannot probe OS family. Unable to mount {device} into {mountpoint}')
+
+    bootlabel = f'Part-{disk:02d}-{partition:02d}'
+    esp, esp_disk, esp_part_number = get_efi_partition(disk, enforce_gpt=True)
+    esp_mountpoint = esp.replace('dev', 'mnt')
+    if not mount_mkdir(esp, esp_mountpoint):
+        umount(mountpoint)
+        raise OgError(f'Unable to mount detected EFI System Partition at {esp} into {esp_mountpoint}')
+
+    try:
+        loader_dir = f'{mountpoint}/ogBoot'
+        destination_dir = f'{esp_mountpoint}/EFI/{bootlabel}/Boot'
+        if os.path.exists(destination_dir):
+            try:
+                shutil.rmtree(destination_dir)
+            except OSError as e:
+                raise OgError(f'Failed to delete {destination_dir}: {e}') from e
+        logging.info(f'Copying {loader_dir} into {destination_dir}')
+        try:
+            shutil.copytree(loader_dir, destination_dir)
+        except OSError as e:
+            raise OgError(f'Failed to copy {loader_dir} into {destination_dir}: {e}') from e
+    finally:
+        umount(mountpoint)
+        umount(esp_mountpoint)