From 8ae64f6384766ee16a88a04db38c5a27189dd73b Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@git.wordpress.org>
Date: Fri, 16 Jan 2015 16:45:21 +0000
Subject: [PATCH] Bail out of hierarchy loops in `_pad_term_counts()`.

Taxonomy hierarchy loops should not occur naturally, but when they do, the
logic of `_pad_term_counts()` could result in infinite loops, leading to
timeouts. We avoid this by breaking when a loop is detected.

Fixes #20635.

git-svn-id: https://develop.svn.wordpress.org/trunk@31206 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/taxonomy.php          |  6 ++++++
 tests/phpunit/tests/term/getTerms.php | 25 +++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/src/wp-includes/taxonomy.php b/src/wp-includes/taxonomy.php
index 991f59552f..caf2255856 100644
--- a/src/wp-includes/taxonomy.php
+++ b/src/wp-includes/taxonomy.php
@@ -3916,9 +3916,15 @@ function _pad_term_counts(&$terms, $taxonomy) {
 	}
 
 	// Touch every ancestor's lookup row for each post in each term
+	$ancestors = array();
 	foreach ( $term_ids as $term_id ) {
+		$ancestors[] = $term_id;
 		$child = $term_id;
 		while ( !empty( $terms_by_id[$child] ) && $parent = $terms_by_id[$child]->parent ) {
+			if ( in_array( $parent, $ancestors ) ) {
+				break;
+			}
+
 			if ( !empty( $term_items[$term_id] ) )
 				foreach ( $term_items[$term_id] as $item_id => $touches ) {
 					$term_items[$parent][$item_id] = isset($term_items[$parent][$item_id]) ? ++$term_items[$parent][$item_id]: 1;
diff --git a/tests/phpunit/tests/term/getTerms.php b/tests/phpunit/tests/term/getTerms.php
index 8e0abce271..7b04ac8807 100644
--- a/tests/phpunit/tests/term/getTerms.php
+++ b/tests/phpunit/tests/term/getTerms.php
@@ -1039,6 +1039,31 @@ class Tests_Term_getTerms extends WP_UnitTestCase {
 		$this->assertEqualSets( $expected, $actual );
 	}
 
+	/*
+	 * @ticket 20635
+	 */
+	public function test_pad_counts_should_not_recurse_infinitely_when_term_hierarchy_has_a_loop() {
+		remove_filter( 'wp_update_term_parent', 'wp_check_term_hierarchy_for_loops', 10 );
+
+		$c1 = $this->factory->category->create();
+		$c2 = $this->factory->category->create( array( 'parent' => $c1 ) );
+		$c3 = $this->factory->category->create( array( 'parent' => $c2 ) );
+		wp_update_term( $c1, 'category', array( 'parent' => $c3 ) );
+
+		add_filter( 'wp_update_term_parent', 'wp_check_term_hierarchy_for_loops', 10, 3 );
+
+		$posts = $this->factory->post->create_many( 3 );
+		wp_set_post_terms( $posts[0], $c1, 'category' );
+		wp_set_post_terms( $posts[1], $c2, 'category' );
+		wp_set_post_terms( $posts[2], $c3, 'category' );
+
+		$terms = get_terms( 'category', array(
+			'pad_counts' => true,
+		) );
+
+		$this->assertEqualSets( array( $c1, $c2, $c3 ), wp_list_pluck( $terms, 'term_id' ) );
+	}
+
 	protected function create_hierarchical_terms_and_posts() {
 		$terms = array();