Plugin Editor: Improve reliability of detecting PHP fatal errors when editing an active plugin.

* Invalidate PHP opcache after file is updated to ensure `include` will ''include'' the written changes.
* Define `WP_ADMIN` when activating plugin in sandbox so plugin code targeting admin will be loaded.
* Do actions that get triggered when loading the admin to ensure plugin code runs that could cause errors on plugin editor screen (and lock out access).
* Fix ability to re-activate a plugin after editing a PHP file other than the main plugin file, and ensure PHP fatal error will be displayed in such cases.
* Consolidate duplicated code into `plugin_sandbox_scrape()` and re-use in `activate_plugin()`.
* Show an error notice instead of a success notice when a file is updated but a plugin was deactivated due to a fatal error.
* Update style of warning when editing an active plugin to be styled as an actual warning notice.

See #12423, #21622.
Fixes #39766.

Built from https://develop.svn.wordpress.org/trunk@41560


git-svn-id: http://core.svn.wordpress.org/trunk@41393 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/css/common-rtl.css

@@ -2203,6 +2203,14 @@ h1.nav-tab-wrapper, /* Back-compat for pre-4.4 */
 #template > div {
 	margin-left: 190px;
 }
+#template .active-plugin-edit-warning {
+	margin-top: 1em;
+	margin-left: 30%;
+	margin-left: calc( 184px + 3% );
+}
+#template .active-plugin-edit-warning p {
+	width: auto;
+}
 
 .metabox-holder .stuffbox > h3, /* Back-compat for pre-4.4 */
 .metabox-holder .postbox > h3, /* Back-compat for pre-4.4 */
@@ -3609,9 +3617,10 @@ img {
 		margin-top: -5px;
 	}
 
-	#template > div {
+	#template > div,
+	#template  .active-plugin-edit-warning {
 		float: none;
-		margin: 0;
+		margin: 1em 0;
 		width: auto;
 	}
 

wp-admin/css/common.css

@@ -2203,6 +2203,14 @@ h1.nav-tab-wrapper, /* Back-compat for pre-4.4 */
 #template > div {
 	margin-right: 190px;
 }
+#template .active-plugin-edit-warning {
+	margin-top: 1em;
+	margin-right: 30%;
+	margin-right: calc( 184px + 3% );
+}
+#template .active-plugin-edit-warning p {
+	width: auto;
+}
 
 .metabox-holder .stuffbox > h3, /* Back-compat for pre-4.4 */
 .metabox-holder .postbox > h3, /* Back-compat for pre-4.4 */
@@ -3609,9 +3617,10 @@ img {
 		margin-top: -5px;
 	}
 
-	#template > div {
+	#template > div,
+	#template  .active-plugin-edit-warning {
 		float: none;
-		margin: 0;
+		margin: 1em 0;
 		width: auto;
 	}
 

wp-admin/includes/plugin.php

@@ -555,10 +555,8 @@ function activate_plugin( $plugin, $redirect = '', $network_wide = false, $silen
 		if ( !empty($redirect) )
 			wp_redirect(add_query_arg('_error_nonce', wp_create_nonce('plugin-activation-error_' . $plugin), $redirect)); // we'll override this later if the plugin can be included without fatal error
 		ob_start();
-		wp_register_plugin_realpath( WP_PLUGIN_DIR . '/' . $plugin );
-		$_wp_plugin_file = $plugin;
-		include_once( WP_PLUGIN_DIR . '/' . $plugin );
-		$plugin = $_wp_plugin_file; // Avoid stomping of the $plugin variable in a plugin.
+
+		plugin_sandbox_scrape( $plugin );
 
 		if ( ! $silent ) {
 			/**
@@ -1881,9 +1879,42 @@ function wp_clean_plugins_cache( $clear_update_cache = true ) {
 }
 
 /**
- * @param string $plugin
+ * Simulate loading the WordPress admin with a given plugin active to attempt to generate errors.
+ *
+ * Actions are re-triggered in the WP bootstrap process for the WP Admin, and the WP_ADMIN constant is defined.
+ *
+ * @since 3.0.0
+ * @since 4.4.0 Function was moved into the `wp-admin/includes/plugin.php` file.
+ * @since 4.9.0 Add defining of WP_ADMIN and triggering admin WP bootstrap actions.
+ *
+ * @global array $wp_actions
+ * @param string $plugin Plugin file to load.
  */
 function plugin_sandbox_scrape( $plugin ) {
+	global $wp_actions;
 	wp_register_plugin_realpath( WP_PLUGIN_DIR . '/' . $plugin );
-	include( WP_PLUGIN_DIR . '/' . $plugin );
+
+	if ( ! defined( 'WP_ADMIN' ) ) {
+		define( 'WP_ADMIN', true );
+	}
+
+	$tested_actions = array(
+		'plugins_loaded' => array(),
+		'setup_theme' => array(),
+		'after_setup_theme' => array(),
+		'init' => array(),
+		'wp_loaded' => array(),
+		'admin_init' => array(),
+	);
+	$old_wp_actions = $wp_actions;
+	array_map( 'remove_all_actions', array_keys( $tested_actions ) );
+
+	include( WP_PLUGIN_DIR . '/' . $plugin );
+
+	// Trigger key actions that are done on the plugin editor to cause the relevant plugin hooks to fire and potentially cause errors.
+	foreach ( $tested_actions as $action => $args ) {
+		do_action_ref_array( $action, $args );
+	}
+
+	$wp_actions = $old_wp_actions; // Restore actions.
 }

wp-admin/plugin-editor.php

@@ -46,7 +46,20 @@ if ( isset( $_REQUEST['plugin'] ) ) {
 
 if ( empty( $plugin ) ) {
 	if ( $file ) {
+
+		// Locate the plugin for a given plugin file being edited.
+		$file_dirname = dirname( $file );
+		foreach ( array_keys( $plugins ) as $plugin_candidate ) {
+			if ( $plugin_candidate === $file || ( '.' !== $file_dirname && dirname( $plugin_candidate ) === $file_dirname ) ) {
+				$plugin = $plugin_candidate;
+				break;
+			}
+		}
+
+		// Fallback to the file as the plugin.
+		if ( empty( $plugin ) ) {
 			$plugin = $file;
+		}
 	} else {
 		$plugin = array_keys( $plugins );
 		$plugin = $plugin[0];
@@ -72,6 +85,10 @@ if ( isset( $_REQUEST['action'] ) && 'update' === $_REQUEST['action'] ) {
 		fwrite($f, $newcontent);
 		fclose($f);
 
+		if ( preg_match( '/\.php$/', $real_file ) && function_exists( 'opcache_invalidate' ) ) {
+			opcache_invalidate( $real_file, true );
+		}
+
 		$network_wide = is_plugin_active_for_network( $file );
 
 		// Deactivate so we can test it.
@@ -220,12 +237,12 @@ if ( isset( $_REQUEST['action'] ) && 'update' === $_REQUEST['action'] ) {
 <?php if (isset($_GET['a'])) : ?>
  <div id="message" class="updated notice is-dismissible"><p><?php _e('File edited successfully.') ?></p></div>
 <?php elseif (isset($_GET['phperror'])) : ?>
- <div id="message" class="updated"><p><?php _e('This plugin has been deactivated because your changes resulted in a <strong>fatal error</strong>.') ?></p>
+ <div id="message" class="notice notice-error"><p><?php _e( 'This plugin has been deactivated because your changes resulted in a <strong>fatal error</strong>.' ); ?></p>
 	<?php
-		if ( wp_verify_nonce( $_GET['_error_nonce'], 'plugin-activation-error_' . $file ) ) {
+		if ( wp_verify_nonce( $_GET['_error_nonce'], 'plugin-activation-error_' . $plugin ) ) {
 			$iframe_url = add_query_arg( array(
 				'action'   => 'error_scrape',
-				'plugin'   => urlencode( $file ),
+				'plugin'   => urlencode( $plugin ),
 				'_wpnonce' => urlencode( $_GET['_error_nonce'] ),
 			), admin_url( 'plugins.php' ) );
 			?>
@@ -315,7 +332,9 @@ foreach ( $plugin_files as $plugin_file ) :
 		<?php endif; ?>
 <?php if ( is_writeable($real_file) ) : ?>
 	<?php if ( in_array( $plugin, (array) get_option( 'active_plugins', array() ) ) ) { ?>
+		<div class="notice notice-warning inline active-plugin-edit-warning">
 			<p><?php _e('<strong>Warning:</strong> Making changes to active plugins is not recommended. If your changes cause a fatal error, the plugin will be automatically deactivated.'); ?></p>
+		</div>
 	<?php } ?>
 	<p class="submit">
 	<?php

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41559';
+$wp_version = '4.9-alpha-41560';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.