Source

File: wp-admin/includes/post.php

function wp_edit_attachments_query_vars( $q = false ) {
	if ( false === $q ) {
		$q = $_GET;
	}
	$q['m']         = isset( $q['m'] ) ? (int) $q['m'] : 0;
	$q['cat']       = isset( $q['cat'] ) ? (int) $q['cat'] : 0;
	$q['post_type'] = 'attachment';
	$post_type      = get_post_type_object( 'attachment' );
	$states         = 'inherit';
	if ( current_user_can( $post_type->cap->read_private_posts ) ) {
		$states .= ',private';
	}

	$q['post_status'] = isset( $q['status'] ) && 'trash' === $q['status'] ? 'trash' : $states;
	$q['post_status'] = isset( $q['attachment-filter'] ) && 'trash' === $q['attachment-filter'] ? 'trash' : $states;

	$media_per_page = (int) get_user_option( 'upload_per_page' );
	if ( empty( $media_per_page ) || $media_per_page < 1 ) {
		$media_per_page = 20;
	}

	/**
	 * Filters the number of items to list per page when listing media items.
	 *
	 * @since 2.9.0
	 *
	 * @param int $media_per_page Number of media to list. Default 20.
	 */
	$q['posts_per_page'] = apply_filters( 'upload_per_page', $media_per_page );

	$post_mime_types = get_post_mime_types();
	if ( isset( $q['post_mime_type'] ) && ! array_intersect( (array) $q['post_mime_type'], array_keys( $post_mime_types ) ) ) {
		unset( $q['post_mime_type'] );
	}

	foreach ( array_keys( $post_mime_types ) as $type ) {
		if ( isset( $q['attachment-filter'] ) && "post_mime_type:$type" === $q['attachment-filter'] ) {
			$q['post_mime_type'] = $type;
			break;
		}
	}

	if ( isset( $q['detached'] ) || ( isset( $q['attachment-filter'] ) && 'detached' === $q['attachment-filter'] ) ) {
		$q['post_parent'] = 0;
	}

	if ( isset( $q['mine'] ) || ( isset( $q['attachment-filter'] ) && 'mine' === $q['attachment-filter'] ) ) {
		$q['author'] = get_current_user_id();
	}

	// Filter query clauses to include filenames.
	if ( isset( $q['s'] ) ) {
		add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
	}

	return $q;
}