Fix Mastodon import for archives with nested root folder (#2581)

Author: obenland

.github/changelog/2581-from-description

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Mastodon importer now unpacks nested archives instead of getting confused by the extra folder.

includes/wp-admin/import/class-mastodon.php

@@ -225,15 +225,15 @@ public static function import() {
 
 		// Unzip package to working directory.
 		\unzip_file( $file, self::$archive );
-		$files = $wp_filesystem->dirlist( self::$archive );
+		self::maybe_unwrap_archive();
 
-		if ( ! isset( $files['outbox.json'] ) ) {
+		if ( ! $wp_filesystem->exists( self::$archive . '/outbox.json' ) ) {
 			echo '<p><strong>' . \esc_html( $error_message ) . '</strong><br />';
 			echo \esc_html__( 'The archive does not contain an Outbox file, please try again.', 'activitypub' ) . '</p>';
+			return;
 		}
 
-		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
-		self::$outbox = \json_decode( \file_get_contents( self::$archive . '/outbox.json' ), true );
+		self::$outbox = \json_decode( $wp_filesystem->get_contents( self::$archive . '/outbox.json' ), true );
 
 		\wp_suspend_cache_invalidation();
 		\wp_defer_term_counting( true );
@@ -434,4 +434,32 @@ private static function prepend_archive_path( $attachment ) {
 
 		return $attachment;
 	}
+
+	/**
+	 * Detect and unwrap single nested directory in archive.
+	 *
+	 * Some Mastodon exports wrap all files in a root folder. This method
+	 * detects this pattern and updates the archive path to point inside it.
+	 */
+	private static function maybe_unwrap_archive() {
+		global $wp_filesystem;
+
+		$files = $wp_filesystem->dirlist( self::$archive );
+
+		// Check if there's exactly one directory at root level.
+		if ( count( $files ) !== 1 ) {
+			return;
+		}
+
+		$first = reset( $files );
+		if ( 'd' !== $first['type'] ) {
+			return;
+		}
+
+		// Check if outbox.json exists inside the nested directory.
+		$nested_path = self::$archive . '/' . $first['name'];
+		if ( $wp_filesystem->exists( $nested_path . '/outbox.json' ) ) {
+			self::$archive = $nested_path;
+		}
+	}
 }

tests/phpunit/tests/includes/wp-admin/import/class-test-mastodon.php

@@ -856,4 +856,41 @@ public function test_import_posts_calls_filter_hook() {
 
 		remove_filter( 'activitypub_import_mastodon_post_data', $filter_callback );
 	}
+
+	/**
+	 * Test maybe_unwrap_archive() unwraps nested folder structure.
+	 */
+	public function test_maybe_unwrap_archive_with_nested_folder() {
+		\WP_Filesystem();
+		global $wp_filesystem;
+
+		// Create temp directory structure: archive/nested-folder/outbox.json.
+		$temp_dir   = \get_temp_dir() . 'activitypub-test-' . \uniqid();
+		$nested_dir = $temp_dir . '/nested-folder';
+
+		\wp_mkdir_p( $nested_dir );
+		$wp_filesystem->put_contents( $nested_dir . '/outbox.json', '{}' );
+
+		// Set self::$archive via Reflection.
+		$reflection = new ReflectionClass( Mastodon::class );
+
+		$archive_property = $reflection->getProperty( 'archive' );
+		if ( \PHP_VERSION_ID < 80100 ) {
+			$archive_property->setAccessible( true );
+		}
+		$archive_property->setValue( null, $temp_dir );
+
+		// Call private method via Reflection.
+		$method = $reflection->getMethod( 'maybe_unwrap_archive' );
+		if ( \PHP_VERSION_ID < 80100 ) {
+			$method->setAccessible( true );
+		}
+		$method->invoke( null );
+
+		// Assert archive path was updated to nested folder.
+		$this->assertSame( $nested_dir, $archive_property->getValue() );
+
+		// Cleanup.
+		$wp_filesystem->delete( $temp_dir, true );
+	}
 }