Move plugin into the FOXML submodule, and update docs.

modules/dgi_migrate_foxml_standard_mods/README.md

@@ -34,6 +34,14 @@ further information.
 
 The migration can be run using the `foxml_to_dgis` migration group.
 
+## Configuration
+
+### Environment variables
+
+| Variable | Default                    | Description                                                                                                                                                        |
+| --- |----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `DGI_MIGRATE_FOXML_STANDARD_MODS_FILE_METHOD` | (unset, defaults to `copy`) | To `copy` or attempt to reference files `direct`ly. Despite configuration, copying will be forced for URIs referencing parts of base64 encoded archival FOXML. |
+
 ## Troubleshooting/Issues
 
 Having problems or solved a problem? Contact

modules/dgi_migrate_foxml_standard_mods/migrations/dgis_orig_file.yml

@@ -89,7 +89,7 @@ process:
         - '@_ext'
       delimiter: '.'
   uri:
-    - plugin: dgi_migrate.foxml_file
+    - plugin: dgi_migrate_foxml_standard_mods.foxml_file
       source: '@_source_uri'
       destination: constants/file_dest
       date: '@created'

modules/dgi_migrate_foxml_standard_mods/migrations/dgis_tn_file.yml

@@ -85,7 +85,7 @@ process:
         - '@_ext'
       delimiter: '.'
   uri:
-    - plugin: dgi_migrate.foxml_file
+    - plugin: dgi_migrate_foxml_standard_mods.foxml_file
       source: '@_source_uri'
       destination: constants/file_dest
       date: '@created'

src/Plugin/migrate/process/FoxmlFile.php → modules/dgi_migrate_foxml_standard_mods/src/Plugin/migrate/process/FoxmlFile.php

@@ -1,8 +1,10 @@
 <?php
 
-namespace Drupal\dgi_migrate\Plugin\migrate\process;
+namespace Drupal\dgi_migrate_foxml_standard_mods\Plugin\migrate\process;
 
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
+use Drupal\dgi_migrate\Plugin\migrate\process\EnsureNonWritableTrait;
 use Drupal\migrate\MigrateExecutableInterface;
 use Drupal\migrate\Plugin\MigrateProcessInterface;
 use Drupal\migrate\Plugin\MigrationInterface;
@@ -16,15 +18,16 @@
  * Accepts:
  * - method: One of "copy" (to copy the file) or "direct" (to directly use the
  *   file). Defaults to "copy". Can be set with the DGI_MIGRATE_FILE_METHOD
- *   environment variable.
+ *   environment variable. Will be forced to "copy" if the value for "source"
+ *   is not of the "foxml://" scheme.
  * - destination: Property in the row containing the destination, to build out
  *   a destination path if copying.
  * - date: Property in the row containing a date with which to build a path in
  *   the destination, when copying.
  * - filename: Property in the row containing a filename.
  *
  * @MigrateProcessPlugin(
- *   id = "dgi_migrate.foxml_file"
+ *   id = "dgi_migrate_foxml_standard_mods.foxml_file"
  * )
  */
 class FoxmlFile extends ProcessPluginBase implements ContainerFactoryPluginInterface {
@@ -40,6 +43,7 @@ public function __construct(
     $plugin_definition,
     protected ?MigrationInterface $migration,
     protected MigrateProcessInterface $naiveCopyPlugin,
+    protected StreamWrapperManagerInterface $streamWrapperManager,
   ) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
   }
@@ -48,7 +52,7 @@ public function __construct(
    * {@inheritDoc}
    */
   public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
-    $configuration['method'] ??= getenv('DGI_MIGRATE_FILE_METHOD') ?: 'copy';
+    $configuration['method'] ??= getenv('DGI_MIGRATE_FOXML_STANDARD_MODS_FILE_METHOD') ?: 'copy';
     assert(in_array($configuration['method'], ['copy', 'direct']));
     /** @var \Drupal\migrate\Plugin\MigratePluginManagerInterface $process_plugin_manager */
     $process_plugin_manager = $container->get('plugin.manager.migrate.process');
@@ -62,14 +66,25 @@ public static function create(ContainerInterface $container, array $configuratio
         'move' => FALSE,
         'file_exists' => 'rename',
       ], $migration),
+      $container->get('stream_wrapper_manager'),
     );
   }
 
   /**
    * {@inheritDoc}
    */
   public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
-    return match ($this->configuration['method']) {
+    $method = $this->configuration['method'];
+    if ($this->streamWrapperManager::getScheme($value) !== 'foxml') {
+      // XXX: If not "foxml://", force to "copy", as it is probably from
+      // archival FOXML, and we do not want to allow for the possibility of
+      // continuous base 64 decoding of datastreams that might entail, nor is
+      // there an an endpoint to support directly serving "php://filter" URIs
+      // nor "foxml.substream://" stream wrappers associated with doing so.
+      $method = 'copy';
+    }
+
+    return match ($method) {
       'copy' => $this->naiveCopyPlugin->transform(
         [
           $value,