do_enclose( string $content = null, int|WP_Post $post )

检查要作为附件添加的视频和音频链接的内容。
Check content for video and audio links to add as enclosures.

说明（Description）

将不添加已添加的存储模块，并将删除不再位于日志中的存储模块。这称为pingback和trackback。

参数（Parameters）

返回（Return）

源码（Source）

/**
 * Check content for video and audio links to add as enclosures.
 *
 * Will not add enclosures that have already been added and will
 * remove enclosures that are no longer in the post. This is called as
 * pingbacks and trackbacks.
 *
 * @since 1.5.0
 *
 * @global wpdb $wpdb
 *
 * @param string $content Post Content.
 * @param int    $post_ID Post ID.
 */
function do_enclose( $content, $post_ID ) {
	global $wpdb;

	//TODO: Tidy this ghetto code up and make the debug code optional
	include_once( ABSPATH . WPINC . '/class-IXR.php' );

	$post_links = array();

	$pung = get_enclosed( $post_ID );

	$post_links_temp = wp_extract_urls( $content );

	foreach ( $pung as $link_test ) {
		if ( ! in_array( $link_test, $post_links_temp ) ) { // link no longer in post
			$mids = $wpdb->get_col( $wpdb->prepare("SELECT meta_id FROM $wpdb->postmeta WHERE post_id = %d AND meta_key = 'enclosure' AND meta_value LIKE %s", $post_ID, $wpdb->esc_like( $link_test ) . '%') );
			foreach ( $mids as $mid )
				delete_metadata_by_mid( 'post', $mid );
		}
	}

	foreach ( (array) $post_links_temp as $link_test ) {
		if ( !in_array( $link_test, $pung ) ) { // If we haven't pung it already
			$test = @parse_url( $link_test );
			if ( false === $test )
				continue;
			if ( isset( $test['query'] ) )
				$post_links[] = $link_test;
			elseif ( isset($test['path']) && ( $test['path'] != '/' ) &&  ($test['path'] != '' ) )
				$post_links[] = $link_test;
		}
	}

	foreach ( (array) $post_links as $url ) {
		if ( $url != '' && !$wpdb->get_var( $wpdb->prepare( "SELECT post_id FROM $wpdb->postmeta WHERE post_id = %d AND meta_key = 'enclosure' AND meta_value LIKE %s", $post_ID, $wpdb->esc_like( $url ) . '%' ) ) ) {

			if ( $headers = wp_get_http_headers( $url) ) {
				$len = isset( $headers['content-length'] ) ? (int) $headers['content-length'] : 0;
				$type = isset( $headers['content-type'] ) ? $headers['content-type'] : '';
				$allowed_types = array( 'video', 'audio' );

				// Check to see if we can figure out the mime type from
				// the extension
				$url_parts = @parse_url( $url );
				if ( false !== $url_parts ) {
					$extension = pathinfo( $url_parts['path'], PATHINFO_EXTENSION );
					if ( !empty( $extension ) ) {
						foreach ( wp_get_mime_types() as $exts => $mime ) {
							if ( preg_match( '!^(' . $exts . ')$!i', $extension ) ) {
								$type = $mime;
								break;
							}
						}
					}
				}

				if ( in_array( substr( $type, 0, strpos( $type, "/" ) ), $allowed_types ) ) {
					add_post_meta( $post_ID, 'enclosure', "$url
$len
$mime
" );
				}
			}
		}
	}
}