Posts: Avoid the use of globals in get_the_content() and related functions.

This changeset introduces `$post` parameters to `get_the_content()` and
`wp_trim_excerpt()`. When a `$post` object is passed to one of these functions,
the functions will operate on the data from that object, rather than from the
post globals (`$authordata`, `$page`, etc). This ensures that the functions work
in a predictable manner when used outside of the regular post loop.

The global-mismatch problem is surfaced in cases where `get_the_excerpt()` is
called outside of the post loop, on posts that don't have a defined excerpt. In
these cases, the post globals - used to generate a fallback excerpt - may refer
to the incorrect object, resulting in PHP notices or other unpredictable
behavior. See #36934 for a related issue.

Props spacedmonkey, kraftbj, Shital Patel.
Fixes #42814.
Built from https://develop.svn.wordpress.org/trunk@44941


git-svn-id: http://core.svn.wordpress.org/trunk@44772 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-query.php

@@ -4155,6 +4155,42 @@ class WP_Query {
 			return;
 		}
 
+		$elements = $this->generate_postdata( $post );
+		if ( false === $elements ) {
+			return;
+		}
+
+		$id           = $elements['id'];
+		$authordata   = $elements['authordata'];
+		$currentday   = $elements['currentday'];
+		$currentmonth = $elements['currentmonth'];
+		$page         = $elements['page'];
+		$pages        = $elements['pages'];
+		$multipage    = $elements['multipage'];
+		$more         = $elements['more'];
+		$numpages     = $elements['numpages'];
+
+		return true;
+	}
+
+	/**
+	 * Generate post data.
+	 *
+	 * @since 5.2.0
+	 *
+	 * @param WP_Post|object|int $post WP_Post instance or Post ID/object.
+	 * @return array|bool $elements Elements of post or false on failure.
+	 */
+	public function generate_postdata( $post ) {
+
+		if ( ! ( $post instanceof WP_Post ) ) {
+			$post = get_post( $post );
+		}
+
+		if ( ! $post ) {
+			return false;
+		}
+
 		$id = (int) $post->ID;
 
 		$authordata = get_userdata( $post->post_author );
@@ -4235,7 +4271,9 @@ class WP_Query {
 		 */
 		do_action_ref_array( 'the_post', array( &$post, &$this ) );
 
-		return true;
+		$elements = compact( 'id', 'authordata', 'currentday', 'currentmonth', 'page', 'pages', 'multipage', 'more', 'numpages' );
+
+		return $elements;
 	}
 	/**
 	 * After looping through a nested query, this function

wp-includes/default-filters.php

@@ -182,7 +182,7 @@ add_filter( 'the_excerpt', 'convert_smilies' );
 add_filter( 'the_excerpt', 'convert_chars' );
 add_filter( 'the_excerpt', 'wpautop' );
 add_filter( 'the_excerpt', 'shortcode_unautop' );
-add_filter( 'get_the_excerpt', 'wp_trim_excerpt' );
+add_filter( 'get_the_excerpt', 'wp_trim_excerpt', 10, 2 );
 
 add_filter( 'the_post_thumbnail_caption', 'wptexturize' );
 add_filter( 'the_post_thumbnail_caption', 'convert_smilies' );

wp-includes/formatting.php

@@ -3678,14 +3678,17 @@ function human_time_diff( $from, $to = '' ) {
  * The ' […]' string can be modified by plugins/themes using the {@see 'excerpt_more'} filter
  *
  * @since 1.5.0
+ * @since 5.2.0 Added the `$post` parameter.
  *
  * @param string             $text Optional. The excerpt. If set to empty, an excerpt is generated.
+ * @param WP_Post|object|int $post Optional. WP_Post instance or Post ID/object. Default is null.
  * @return string The excerpt.
  */
-function wp_trim_excerpt( $text = '' ) {
+function wp_trim_excerpt( $text = '', $post = null ) {
 	$raw_excerpt = $text;
 	if ( '' == $text ) {
-		$text = get_the_content( '' );
+		$post = get_post( $post );
+		$text = get_the_content( '', false, $post );
 
 		$text = strip_shortcodes( $text );
 		$text = excerpt_remove_blocks( $text );

wp-includes/post-template.php

@@ -253,6 +253,7 @@ function the_content( $more_link_text = null, $strip_teaser = false ) {
  * Retrieve the post content.
  *
  * @since 0.71
+ * @since 5.2.0 Added the `$post` parameter.
  *
  * @global int   $page      Page number of a single post/page.
  * @global int   $more      Boolean indicator for whether single post/page is being viewed.
@@ -263,12 +264,23 @@ function the_content( $more_link_text = null, $strip_teaser = false ) {
  *
  * @param string             $more_link_text Optional. Content for when there is more text.
  * @param bool               $strip_teaser   Optional. Strip teaser content before the more text. Default is false.
+ * @param WP_Post|object|int $post           Optional. WP_Post instance or Post ID/object. Default is null.
  * @return string
  */
-function get_the_content( $more_link_text = null, $strip_teaser = false ) {
+function get_the_content( $more_link_text = null, $strip_teaser = false, $post = null ) {
 	global $page, $more, $preview, $pages, $multipage;
 
-	$post = get_post();
+	$_post = get_post( $post );
+
+	if ( ! ( $_post instanceof WP_Post ) ) {
+		return '';
+	}
+
+	if ( null === $post ) {
+		$elements = compact( 'page', 'more', 'preview', 'pages', 'multipage' );
+	} else {
+		$elements = generate_postdata( $_post );
+	}
 
 	if ( null === $more_link_text ) {
 		$more_link_text = sprintf(
@@ -276,7 +288,12 @@ function get_the_content( $more_link_text = null, $strip_teaser = false ) {
 			sprintf(
 				/* translators: %s: Name of current post */
 				__( 'Continue reading %s' ),
-				the_title_attribute( array( 'echo' => false ) )
+				the_title_attribute(
+					array(
+						'echo' => false,
+						'post' => $_post,
+					)
+				)
 			),
 			__( '(more…)' )
 		);
@@ -286,15 +303,16 @@ function get_the_content( $more_link_text = null, $strip_teaser = false ) {
 	$has_teaser = false;
 
 	// If post password required and it doesn't match the cookie.
-	if ( post_password_required( $post ) ) {
+	if ( post_password_required( $_post ) ) {
-		return get_the_password_form( $post );
+		return get_the_password_form( $_post );
 	}
 
-	if ( $page > count( $pages ) ) { // if the requested page doesn't exist
+	if ( $elements['page'] > count( $elements['pages'] ) ) { // if the requested page doesn't exist
-		$page = count( $pages ); // give them the highest numbered page that DOES exist
+		$elements['page'] = count( $elements['pages'] ); // give them the highest numbered page that DOES exist
 	}
 
-	$content = $pages[ $page - 1 ];
+	$page_no = $elements['page'];
+	$content = $elements['pages'][ $page_no - 1 ];
 	if ( preg_match( '/<!--more(.*?)?-->/', $content, $matches ) ) {
 		$content = explode( $matches[0], $content, 2 );
 		if ( ! empty( $matches[1] ) && ! empty( $more_link_text ) ) {
@@ -306,21 +324,21 @@ function get_the_content( $more_link_text = null, $strip_teaser = false ) {
 		$content = array( $content );
 	}
 
-	if ( false !== strpos( $post->post_content, '<!--noteaser-->' ) && ( ! $multipage || $page == 1 ) ) {
+	if ( false !== strpos( $_post->post_content, '<!--noteaser-->' ) && ( ! $elements['multipage'] || $elements['page'] == 1 ) ) {
 		$strip_teaser = true;
 	}
 
 	$teaser = $content[0];
 
-	if ( $more && $strip_teaser && $has_teaser ) {
+	if ( $elements['more'] && $strip_teaser && $has_teaser ) {
 		$teaser = '';
 	}
 
 	$output .= $teaser;
 
 	if ( count( $content ) > 1 ) {
-		if ( $more ) {
+		if ( $elements['more'] ) {
-			$output .= '<span id="more-' . $post->ID . '"></span>' . $content[1];
+			$output .= '<span id="more-' . $_post->ID . '"></span>' . $content[1];
 		} else {
 			if ( ! empty( $more_link_text ) ) {
 
@@ -332,7 +350,7 @@ function get_the_content( $more_link_text = null, $strip_teaser = false ) {
 				 * @param string $more_link_element Read More link element.
 				 * @param string $more_link_text    Read More text.
 				 */
-				$output .= apply_filters( 'the_content_more_link', ' <a href="' . get_permalink() . "#more-{$post->ID}\" class=\"more-link\">$more_link_text</a>", $more_link_text );
+				$output .= apply_filters( 'the_content_more_link', ' <a href="' . get_permalink( $_post ) . "#more-{$_post->ID}\" class=\"more-link\">$more_link_text</a>", $more_link_text );
 			}
 			$output = force_balance_tags( $output );
 		}

wp-includes/query.php

@@ -1111,3 +1111,23 @@ function setup_postdata( $post ) {
 
 	return false;
 }
+
+/**
+ * Generates post data.
+ *
+ * @since 5.2.0
+ *
+ * @global WP_Query $wp_query Global WP_Query instance.
+ *
+ * @param WP_Post|object|int $post WP_Post instance or Post ID/object.
+ * @return array|bool Elements of post, or false on failure.
+ */
+function generate_postdata( $post ) {
+	global $wp_query;
+
+	if ( ! empty( $wp_query ) && $wp_query instanceof WP_Query ) {
+		return $wp_query->generate_postdata( $post );
+	}
+
+	return false;
+}

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.2-alpha-44940';
+$wp_version = '5.2-alpha-44941';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.