Source

File: wp-includes/post.php

function update_attached_file( $attachment_id, $file ) {
	if ( ! get_post( $attachment_id ) ) {
		return false;
	}

	/**
	 * Filters the path to the attached file to update.
	 *
	 * @since 2.1.0
	 *
	 * @param string $file          Path to the attached file to update.
	 * @param int    $attachment_id Attachment ID.
	 */
	$file = apply_filters( 'update_attached_file', $file, $attachment_id );

	$file = _wp_relative_upload_path( $file );
	if ( $file ) {
		return update_post_meta( $attachment_id, '_wp_attached_file', $file );
	} else {
		return delete_post_meta( $attachment_id, '_wp_attached_file' );
	}
}