adaptation of the media search plugin to work within the med

<?php
/** TEST
 * http://wordpress.org/support/topic/media-search
 * adaptation of the media search plugin to work within the media popup
 *
 * Plugin Name: Media Search
 * Description: Search media by attached page
 * Version: ***
 * Author: Valera Satsura
 * Author URI: http://satsura.com
 */

/**
 * Rewrite search for media library in admin area
 * @param $request
 * @return string
 */
function media_by_page_search( $request ) {
    global $pagenow, $wpdb;

	if ( is_admin() ) {
		$searchstring = NULL;
		$paged = 1;
		$post_mime_type = NULL;

		// check if this is the media popup (ajax call POST)
		if ( isset($_POST['action']) && $_POST['action'] == 'query-attachments' ) {
			if (isset($_POST['query'])) {
				$post_query = $_POST['query'];
				$searchstring = $post_query['s'];
				$post_mime_type = $post_query['post_mime_type'];
				$paged = $post_query['paged'];
			}
		}

		// check if this is the media library page (GET)
		if ( $pagenow == 'upload.php' && isset($_GET['s']) && !empty($_GET['s']) ) {
			$searchstring = $_GET['s'];
			if (isset($_GET['post_mime_type']))
				$post_mime_type = $_GET['post_mime_type'];
			$paged = get_query_var( 'paged' );
		}

		// That search works only on "Media Library"
		if ( isset($searchstring) && $searchstring != '' ) {

			// Get page limits
			$media_per_page = (int) get_user_option( 'upload_per_page' );
			if ( empty( $media_per_page ) || $media_per_page < 1 )
				$media_per_page = 40;
			$media_per_page = apply_filters( 'upload_per_page', $media_per_page );

			// Start page, $paged = current page number
			$start = (int) $media_per_page * (int) ( (int) $paged - 1 );

			// SQL to search

			// wp_posts > post_title = img title
			// wp_posts > post_content = img description
			// wp_posts > post_excerpt = img caption
			// wp_postmeta > _wp_attachment_image_alt = img alt txt
			// wp_postmeta > _wp_attached_file = path
			$request = "SELECT SQL_CALC_FOUND_ROWS  wp_posts.* FROM wp_posts
				WHERE 1=1
				AND
					(
						(
							(wp_posts.post_title LIKE '%" . $searchstring . "%')
							OR (wp_posts.post_content LIKE '%" . $searchstring . "%')
							OR (wp_posts.post_excerpt LIKE '%" . $searchstring . "%')
						)
						OR
						(
							ID IN
							(
							  select post_id from $wpdb->postmeta as b where b.meta_key = ('_wp_attachment_image_alt' or '_wp_attached_file') and b.meta_value like '%" . $searchstring . "%'
							)
						)
						OR
						(
							post_parent IN
							(
							  select ID from $wpdb->posts as c where c.post_type <> 'attachment' and c.post_title like '%" . $searchstring . "%'
							)
						)
					)
				AND
					wp_posts.post_type = 'attachment'
				AND
					(
						wp_posts.post_status = 'inherit' OR wp_posts.post_status = 'private'
					)";

				if ($post_mime_type && $searchstring != '')
					$request .= " AND
					(
						wp_posts.post_mime_type like '%" . $post_mime_type . "%'
					)";


				$request .= " ORDER BY wp_posts.post_date DESC LIMIT " . (int)$start . ", " . (int)$media_per_page;

		}
	}
    return $request;
}

// Register new search
add_filter( 'posts_request' , 'media_by_page_search' );