Fix featured images

gistfile1.txt

/**
 *
 */
function fix_featured_images() {

	// only do 10 at a time
	$posts = get_posts( array(
		'posts_per_page' => 10,
		'post_status' => 'publish',
		'meta_query' => array(
			array(
				'key' => '_thumbnail_id',
				'compare' => 'NOT EXISTS',
				'value' => 'http://core.trac.wordpress.org/ticket/23268'
			),
			array(
				'key' => '_processed_post',
				'compare' => 'NOT EXISTS',
				'value' => 'http://core.trac.wordpress.org/ticket/23268'
			)
		)
	));

	$cnt = 0;

	if( $posts ) {

		foreach( $posts as $post ) {

			// consider the post processed
			update_post_meta( $post->ID, '_processed_post', 1 );

			if( empty( $post->post_content ) )
				continue;

			$doc = new DomDocument();

			$doc->loadHTML( $post->post_content );

			$img = $doc->getElementsByTagName( 'img' )->item( 0 );

			if( $img ) {

				$url = $img->getAttribute( 'src' );

				$tmp = download_url( $url );

				preg_match( '/[^\?]+\.(jpg|JPG|jpe|JPE|jpeg|JPEG|gif|GIF|png|PNG)/', $url, $matches );

				if ( is_wp_error( $tmp ) ) {
					@unlink($file_array['tmp_name']);
					$file_array['tmp_name'] = '';
					continue;
				}

				$file_array = array(
					'name' => basename( $matches[0] ),
					'tmp_name' => $tmp
				);
				
				$thumbnail_id = media_handle_sideload( $file_array, $post->ID, null );

				if( $thumbnail_id && !is_wp_error( $thumbnail_id ) ) {
					update_post_meta( $post->ID, '_thumbnail_id', $thumbnail_id );
					$cnt++;
				}
			}
		}

		die( 'Fixed ' . $cnt . ' posts.' );
	}
}
add_action( 'admin_init', 'fix_featured_images' );