Fix parsing of inner blocks when auto-generating an excerpt. Helps to prevent cases where dynamic inner blocks may cause an infinite loop if trying to auto-generate an excerpt.

Props desrosj, pento, gziolo, azaozz.
Fixes #46133.

git-svn-id: https://develop.svn.wordpress.org/trunk@45265 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/blocks.php

@@ -125,10 +125,9 @@ function get_dynamic_block_names() {
  * @return string The parsed and filtered content.
  */
 function excerpt_remove_blocks( $content ) {
-	$allowed_blocks = array(
+	$allowed_inner_blocks = array(
 		// Classic blocks have their blockName set to null.
 		null,
-		'core/columns',
 		'core/freeform',
 		'core/heading',
 		'core/html',
@@ -141,6 +140,9 @@ function excerpt_remove_blocks( $content ) {
 		'core/table',
 		'core/verse',
 	);
+
+	$allowed_blocks = array_merge( $allowed_inner_blocks, array( 'core/columns' ) );
+
 	/**
 	 * Filters the list of blocks that can contribute to the excerpt.
 	 *
@@ -154,12 +156,55 @@ function excerpt_remove_blocks( $content ) {
 	$allowed_blocks = apply_filters( 'excerpt_allowed_blocks', $allowed_blocks );
 	$blocks         = parse_blocks( $content );
 	$output         = '';
+
 	foreach ( $blocks as $block ) {
 		if ( in_array( $block['blockName'], $allowed_blocks, true ) ) {
+			if ( ! empty( $block['innerBlocks'] ) ) {
+				if ( 'core/columns' === $block['blockName'] ) {
+					$output .= _excerpt_render_inner_columns_blocks( $block, $allowed_inner_blocks );
+					continue;
+				}
+
+				// Skip the block if it has disallowed or nested inner blocks.
+				foreach ( $block['innerBlocks'] as $inner_block ) {
+					if (
+						! in_array( $inner_block['blockName'], $allowed_inner_blocks, true ) ||
+						! empty( $inner_block['innerBlocks'] )
+					) {
+						continue 2;
+					}
+				}
+			}
+
 			$output .= render_block( $block );
 		}
 	}
-	 return $output;
+
+	return $output;
+}
+
+/**
+ * Render inner blocks from the `core/columns` block for generating an excerpt.
+ *
+ * @since 5.2.0
+ * @access private
+ *
+ * @param array $columns        The parsed columns block.
+ * @param array $allowed_blocks The list of allowed inner blocks.
+ * @return string The rendered inner blocks.
+ */
+function _excerpt_render_inner_columns_blocks( $columns, $allowed_blocks ) {
+	$output = '';
+
+	foreach ( $columns['innerBlocks'] as $column ) {
+		foreach ( $column['innerBlocks'] as $inner_block ) {
+			if ( in_array( $inner_block['blockName'], $allowed_blocks, true ) && empty( $inner_block['innerBlocks'] ) ) {
+				$output .= render_block( $inner_block );
+			}
+		}
+	}
+
+	return $output;
 }
 
 /**

tests/phpunit/tests/formatting/ExcerptRemoveBlocks.php

@@ -0,0 +1,129 @@
+<?php
+
+/**
+ * @group formatting
+ * @covers ::excerpt_remove_blocks
+ * @ticket 46133
+ */
+class Tests_Formatting_ExcerptRemoveBlocks extends WP_UnitTestCase {
+
+	public static $post_id;
+
+	public $content = '
+<!-- wp:paragraph -->
+<p>paragraph</p>
+<!-- /wp:paragraph -->
+<!-- wp:latest-posts {"postsToShow":3,"displayPostDate":true,"order":"asc","orderBy":"title"} /-->
+<!-- wp:spacer -->
+<div style="height:100px" aria-hidden="true" class="wp-block-spacer"></div>
+<!-- /wp:spacer -->
+<!-- wp:columns {"columns":1} -->
+<div class="wp-block-columns has-1-columns">
+	<!-- wp:column -->
+	<div class="wp-block-column">
+		<!-- wp:archives {"displayAsDropdown":false,"showPostCounts":false} /-->
+		
+		<!-- wp:paragraph -->
+		<p>paragraph inside column</p>
+		<!-- /wp:paragraph -->
+	</div>
+	<!-- /wp:column -->
+</div>
+<!-- /wp:columns -->
+';
+
+	public $filtered_content = '
+
+<p>paragraph</p>
+
+
+
+
+		<p>paragraph inside column</p>
+		
+';
+
+	/**
+	 * Fake block rendering function.
+	 *
+	 * @since 5.2.0
+	 *
+	 * @return string Block output.
+	 */
+	function render_fake_block() {
+		return get_the_excerpt( self::$post_id );
+	}
+
+	/**
+	 * Set up.
+	 *
+	 * @since 5.2.0
+	 */
+	function setUp() {
+		parent::setUp();
+		self::$post_id = $this->factory()->post->create(
+			array(
+				'post_excerpt' => '', // Empty excerpt, so it has to be generated.
+				'post_content' => '<!-- wp:core/fake /-->',
+			)
+		);
+		register_block_type(
+			'core/fake',
+			array(
+				'render_callback' => array( $this, 'render_fake_block' ),
+			)
+		);
+	}
+
+	/**
+	 * Tear down.
+	 *
+	 * @since 5.2.0
+	 */
+	function tearDown() {
+		parent::tearDown();
+		$registry = WP_Block_Type_Registry::get_instance();
+		$registry->unregister( 'core/fake' );
+		wp_delete_post( self::$post_id, true );
+	}
+
+	/**
+	 * Tests excerpt_remove_blocks().
+	 *
+	 * @ticket 46133
+	 */
+	function test_excerpt_remove_blocks() {
+		// Simple dynamic block..
+		$content = '<!-- wp:core/block /-->';
+
+		$this->assertEmpty( excerpt_remove_blocks( $content ) );
+
+		// Dynamic block with options, embedded in other content.
+		$this->assertEquals( $this->filtered_content, excerpt_remove_blocks( $this->content ) );
+	}
+
+	/**
+	 * Tests that dynamic blocks don't cause an out-of-memory error.
+	 *
+	 * When dynamic blocks happen to generate an excerpt, they can cause an
+	 * infinite loop if that block is part of the post's content.
+	 *
+	 * `wp_trim_excerpt()` applies the `the_content` filter, which has
+	 * `do_blocks` attached to it, trying to render the block which again will
+	 * attempt to return an excerpt of that post.
+	 *
+	 * This infinite loop can be avoided by stripping dynamic blocks before
+	 * `the_content` gets applied, just like shortcodes.
+	 *
+	 * @ticket 46133
+	 */
+	function test_excerpt_infinite_loop() {
+		$query = new WP_Query(
+			array(
+				'post__in' => array( self::$post_id ),
+			)
+		);
+		$query->the_post();
+		$this->assertEmpty( do_blocks( '<!-- wp:core/fake /-->' ) );
+	}
+}