14662.diff on Ticket #14662 – Attachment – WordPress Trac

wp-includes/default-filters.php

         add_filter( $filter, 'convert_chars' );
+}
+// Pre save hierarchy
+add_filter( 'wp_insert_post_parent', 'wp_check_post_hierarchy_for_loops', 10, 2 );
+add_filter( 'wp_update_term_parent', 'wp_check_term_hierarchy_for_loops', 10, 3 );
 // Display filters
 add_filter( 'the_title', 'wptexturize'   );
 add_filter( 'the_title', 'convert_chars' );

wp-includes/taxonomy.php

+                }
+        }
+        // Check $parent to see if it will cause a hierarchy loop
+        $parent = apply_filters( 'wp_update_term_parent', $parent, $term_id, $taxonomy, compact( array_keys( $args ) ), $args );
         // Check for duplicate slug
         $id = $wpdb->get_var( $wpdb->prepare( "SELECT term_id FROM $wpdb->terms WHERE slug = %s", $slug ) );
         if ( $id && ($id != $term_id) ) {
 …
         return false;
+}
+/**
+ * Checks the given subset of the term hierarchy for hierarchy loops.
+ * Prevents loops from forming and breaks those that it finds.
+ *
+ * Attached to the wp_update_term_parent filter.
+ *
+ * @since 3.1
+ * @uses WP_Term_Parent_Map
+ * @uses wp_find_hierarchy_loop()
+ *
+ * @param int $parent term_id of the parent for the term we're checking.
+ * @parem int $term_id The term we're checking.
+ *
+ * @return int The new parent for the term.
+ */
+function wp_check_term_hierarchy_for_loops( $parent, $term_id, $taxonomy ) {
+        // Nothing fancy here - bail
+        if ( !$parent )
+                return 0;
+        // Can't be its own parent
+        if ( $parent == $term_id )
+                return 0;
+        // Now look for larger loops
+        $term_parent_map = new WP_Term_Parent_Map( $taxonomy, array( $term_id => $parent ) );
+        if ( !$loop = wp_find_hierarchy_loop( $term_parent_map, $term_id ) )
+                return $parent; // No loop
+        // Setting $parent to the given value causes a loop
+        if ( isset( $loop[$term_id] ) )
+                return 0;
+        // There's a loop, but it doesn't contain $term_id.  Break the loop.
+        foreach ( array_keys( $loop ) as $loop_member )
+                $term_parent_map[$loop_member] = 0;
+        return $parent;
+}
+/**
+ * Simulates array( $term_id => $parent, ... ) without having to load all terms.
+ *
+ * @link http://php.net/manual/class.arrayaccess.php
+ *
+ * @since 3.1
+ */
+class WP_Term_Parent_Map implements ArrayAccess {
+        public $taxonomy = '';
+        public $override = array();
+        /**
+         * @param string $taxonomy
+         * @param array $override A list of term_id => parent mappings used to override the results of get_term()->parent.
+         *              Useful when checking for loops in hierarchies that are not yet stored in the DB.
+         */
+        public function __construct( $taxonomy, $override = array() ) {
+                $this->taxonomy = $taxonomy;
+                $this->override = $override;
+        }
+        /* ArrayAccess */
+        public function offsetExists( $offset ) {
+                if ( isset( $this->override[$offset] ) )
+                        return true;
+                $term = get_term( $offset, $this->taxonomy );
+                return $term && !is_wp_error( $term );
+        }
+        public function offsetGet( $offset ) {
+                if ( isset( $this->override[$offset] ) )
+                        return $this->override[$offset];
+                $term = get_term( $offset, $this->taxonomy );
+                if ( !$term || is_wp_error( $term ) )
+                        return;
+                return (int) $term->parent;
+        }
+        public function offsetSet( $offset, $value ) {
+                if ( isset( $this->override[$offset] ) )
+                        $this->override[$offset] = $value;
+                else
+                        wp_update_term( $offset, $this->taxonomy, array( 'parent' => $value ) );
+        }
+        public function offsetUnset( $offset ) {
+                if ( isset( $this->override[$offset] ) )
+                        unset( $this->override[$offset] );
+                // else noop
+        }
+}

wp-includes/post.php

         else
                 $post_parent = 0;
+        if ( !empty($post_ID) ) {
+                if ( $post_parent == $post_ID ) {
+                        // Post can't be its own parent
+                        $post_parent = 0;
+                } elseif ( !empty($post_parent) ) {
+                        $parent_post = get_post($post_parent);
+                        // Check for circular dependency
+                        if ( isset( $parent_post->post_parent ) && $parent_post->post_parent == $post_ID )
+                                $post_parent = 0;
+                }
+        }
+        // Check the post_parent to see if it will cause a hierarchy loop
+        $post_parent = apply_filters( 'wp_insert_post_parent', $post_parent, $post_ID, compact( array_keys( $postarr ) ), $postarr );
         if ( isset($menu_order) )
                 $menu_order = (int) $menu_order;
 …
                 add_filter('the_preview', '_set_preview');
+        }
+}
+/**
+ * Checks the given subset of the post hierarchy for hierarchy loops.
+ * Prevents loops from forming and breaks those that it finds.
+ *
+ * Attached to the wp_insert_post_parent filter.
+ *
+ * @since 3.1
+ * @uses WP_Post_Parent_Map
+ * @uses wp_find_hierarchy_loop()
+ *
+ * @param int $post_parent ID of the parent for the post we're checking.
+ * @parem int $post_ID ID of the post we're checking.
+ *
+ * @return int The new post_parent for the post.
+ */
+function wp_check_post_hierarchy_for_loops( $post_parent, $post_ID ) {
+        // Nothing fancy here - bail
+        if ( !$post_parent )
+                return 0;
+        // New post can't cause a loop
+        if ( empty( $post_ID ) )
+                return $post_parent;
+        // Can't be its own parent
+        if ( $post_parent == $post_ID )
+                return 0;
+        // Now look for larger loops
+        $post_parent_map = new WP_Post_Parent_Map( array( $post_ID => $post_parent ) );
+        if ( !$loop = wp_find_hierarchy_loop( $post_parent_map, $post_ID ) )
+                return $post_parent; // No loop
+        // Setting $post_parent to the given value causes a loop
+        if ( isset( $loop[$post_ID] ) )
+                return 0;
+        // There's a loop, but it doesn't contain $post_ID.  Break the loop.
+        foreach ( array_keys( $loop ) as $loop_member )
+                $post_parent_map[$loop_member] = 0;
+        return $post_parent;
+}
+/**
+ * Simulates array( $post_id => $post_parent, ... ) without having to load all posts.
+ *
+ * @link http://php.net/manual/class.arrayaccess.php
+ *
+ * @since 3.1
+ */
+class WP_Post_Parent_Map implements ArrayAccess {
+        public $override = array();
+        /**
+         * @param array $override A list of post_ID => post_parent mappings used to override the results of get_post()->post_parent.
+         *              Useful when checking for loops in hierarchies that are not yet stored in the DB.
+         */
+        public function __construct( $override = array() ) {
+                $this->override = $override;
+        }
+        /* ArrayAccess */
+        public function offsetExists( $offset ) {
+                if ( isset( $this->override[$offset] ) )
+                        return true;
+                return (bool) get_post( $offset );
+        }
+        public function offsetGet( $offset ) {
+                if ( isset( $this->override[$offset] ) )
+                        return $this->override[$offset];
+                if ( !$post = get_post( $offset ) )
+                        return;
+                return (int) $post->post_parent;
+        }
+        public function offsetSet( $offset, $value ) {
+                if ( isset( $this->override[$offset] ) )
+                        $this->override[$offset] = $value;
+                else
+                        wp_update_post( array( 'ID' => $offset, 'post_parent' => $value ) );
+        }
+        public function offsetUnset( $offset ) {
+                if ( isset( $this->override[$offset] ) )
+                        unset( $this->override[$offset] );
+                // else noop
+        }
+}

wp-includes/functions.php

+        }
+}
+?>
+/**
+ * Finds hierarchy loops in an array that maps objects to parents.
+ *
+ * @since 3.1
+ *
+ * @param array $map array( ID => parent_ID, ... )
+ * @param $start The ID to start the loop check at
+ *
+ * @return array IDs of all members of loop
+ */
+function wp_find_hierarchy_loop( $map, $start ) {
+        if ( !$arbitrary_loop_member = wp_find_hierarchy_loop_tortoise_hare( $map, $start ) )
+                return array();
+        return wp_find_hierarchy_loop_tortoise_hare( $map, $arbitrary_loop_member, true );
+}
+/**
+ * Uses the "The Tortoise and the Hare" algorithm to detect loops.
+ *
+ * For every step of the algorithm, the hare takes two steps and the tortoise one.
+ * If the hare ever laps the tortoise, there must be a loop.
+ *
+ * @since 3.1
+ *
+ * @param array $map array( ID => parent_ID, ... )
+ * @param $start The ID to start the loop check at
+ * @param bool $_return_loop Return loop members or just detect presence of loop?
+ *             Only set to true if you already know the given $start is part of a loop
+ *             (otherwise the returned array might include branches)
+ *
+ * @return mixed scalar ID of some arbitrary member of the loop, or array of IDs of all members of loop if $_return_loop
+ */
+function wp_find_hierarchy_loop_tortoise_hare( $map, $start, $_return_loop = false ) {
+        $tortoise = $hare = $evanescent_hare = $start;
+        $return = array();
+        // Set evanescent_hare to one past hare
+        // Increment hare two steps
+        while ( $tortoise && ( $evanescent_hare = $map[$hare] ) && ( $hare = $map[$evanescent_hare] ) ) {
+                if ( $_return_loop )
+                        $return[$tortoise] = $return[$evanescent_hare] = $return[$hare] = true;
+                // tortoise got lapped - must be a loop
+                if ( $tortoise == $evanescent_hare ) {
+                        unset( $return[$hare] ); // $hare is not actually in the loop
+                        return $_return_loop ? $return : $tortoise;
+                } else if ( $tortoise == $hare ) {
+                        return $_return_loop ? $return : $tortoise;
+                }
+                $tortoise = $map[$tortoise]; // Increment tortoise by one step
+        }
+        return false;
+}

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Ticket #14662: 14662.diff

wp-includes/default-filters.php

wp-includes/taxonomy.php

wp-includes/post.php

wp-includes/functions.php

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