<form method="POST">
    <h3>Editing: rss.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
/**
 * Server-side rendering of the `core/rss` block.
 *
 * @package WordPress
 */

/**
 * Renders the `core/rss` block on server.
 *
 * @since 5.2.0
 *
 * @param array $attributes The block attributes.
 *
 * @return string Returns the block content with received rss items.
 */
function render_block_core_rss( $attributes ) {
	if ( in_array( untrailingslashit( $attributes['feedURL'] ), array( site_url(), home_url() ), true ) ) {
		return '&lt;div class=&quot;components-placeholder&quot;&gt;&lt;div class=&quot;notice notice-error&quot;&gt;' . __( 'Adding an RSS feed to this site’s homepage is not supported, as it could lead to a loop that slows down your site. Try using another block, like the &lt;strong&gt;Latest Posts&lt;/strong&gt; block, to list posts from the site.' ) . '&lt;/div&gt;&lt;/div&gt;';
	}

	$rss = fetch_feed( $attributes['feedURL'] );

	if ( is_wp_error( $rss ) ) {
		return '&lt;div class=&quot;components-placeholder&quot;&gt;&lt;div class=&quot;notice notice-error&quot;&gt;&lt;strong&gt;' . __( 'RSS Error:' ) . '&lt;/strong&gt; ' . esc_html( $rss-&gt;get_error_message() ) . '&lt;/div&gt;&lt;/div&gt;';
	}

	if ( ! $rss-&gt;get_item_quantity() ) {
		return '&lt;div class=&quot;components-placeholder&quot;&gt;&lt;div class=&quot;notice notice-error&quot;&gt;' . __( 'An error has occurred, which probably means the feed is down. Try again later.' ) . '&lt;/div&gt;&lt;/div&gt;';
	}

	$rss_items  = $rss-&gt;get_items( 0, $attributes['itemsToShow'] );
	$list_items = '';
	foreach ( $rss_items as $item ) {
		$title = esc_html( trim( strip_tags( $item-&gt;get_title() ) ) );
		if ( empty( $title ) ) {
			$title = __( '(no title)' );
		}
		$link = $item-&gt;get_link();
		$link = esc_url( $link );
		if ( $link ) {
			$title = &quot;&lt;a href='{$link}'&gt;{$title}&lt;/a&gt;&quot;;
		}
		$title = &quot;&lt;div class='wp-block-rss__item-title'&gt;{$title}&lt;/div&gt;&quot;;

		$date = '';
		if ( $attributes['displayDate'] ) {
			$date = $item-&gt;get_date( 'U' );

			if ( $date ) {
				$date = sprintf(
					'&lt;time datetime=&quot;%1$s&quot; class=&quot;wp-block-rss__item-publish-date&quot;&gt;%2$s&lt;/time&gt; ',
					esc_attr( date_i18n( 'c', $date ) ),
					esc_attr( date_i18n( get_option( 'date_format' ), $date ) )
				);
			}
		}

		$author = '';
		if ( $attributes['displayAuthor'] ) {
			$author = $item-&gt;get_author();
			if ( is_object( $author ) ) {
				$author = $author-&gt;get_name();
				if ( ! empty( $author ) ) {
					$author = '&lt;span class=&quot;wp-block-rss__item-author&quot;&gt;' . sprintf(
						/* translators: byline. %s: author. */
						__( 'by %s' ),
						esc_html( strip_tags( $author ) )
					) . '&lt;/span&gt;';
				}
			}
		}

		$excerpt     = '';
		$description = $item-&gt;get_description();
		if ( $attributes['displayExcerpt'] &amp;&amp; ! empty( $description ) ) {
			$excerpt = html_entity_decode( $description, ENT_QUOTES, get_option( 'blog_charset' ) );
			$excerpt = esc_attr( wp_trim_words( $excerpt, $attributes['excerptLength'], ' [&amp;hellip;]' ) );

			// Change existing [...] to [&amp;hellip;].
			if ( '[...]' === substr( $excerpt, -5 ) ) {
				$excerpt = substr( $excerpt, 0, -5 ) . '[&amp;hellip;]';
			}

			$excerpt = '&lt;div class=&quot;wp-block-rss__item-excerpt&quot;&gt;' . esc_html( $excerpt ) . '&lt;/div&gt;';
		}

		$list_items .= &quot;&lt;li class='wp-block-rss__item'&gt;{$title}{$date}{$author}{$excerpt}&lt;/li&gt;&quot;;
	}

	$classnames = array();
	if ( isset( $attributes['blockLayout'] ) &amp;&amp; 'grid' === $attributes['blockLayout'] ) {
		$classnames[] = 'is-grid';
	}
	if ( isset( $attributes['columns'] ) &amp;&amp; 'grid' === $attributes['blockLayout'] ) {
		$classnames[] = 'columns-' . $attributes['columns'];
	}
	if ( $attributes['displayDate'] ) {
		$classnames[] = 'has-dates';
	}
	if ( $attributes['displayAuthor'] ) {
		$classnames[] = 'has-authors';
	}
	if ( $attributes['displayExcerpt'] ) {
		$classnames[] = 'has-excerpts';
	}

	$wrapper_attributes = get_block_wrapper_attributes( array( 'class' =&gt; implode( ' ', $classnames ) ) );

	return sprintf( '&lt;ul %s&gt;%s&lt;/ul&gt;', $wrapper_attributes, $list_items );
}

/**
 * Registers the `core/rss` block on server.
 *
 * @since 5.2.0
 */
function register_block_core_rss() {
	register_block_type_from_metadata(
		__DIR__ . '/rss',
		array(
			'render_callback' =&gt; 'render_block_core_rss',
		)
	);
}
add_action( 'init', 'register_block_core_rss' );
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