- Patch #742246 by jbrown, noahb, aspilicious, alexanderpas, rfay:handle uncaught exceptions.

includes/bootstrap.inc

@@ -2051,11 +2051,10 @@ function _drupal_exception_handler($exception) {
   catch (Exception $exception2) {
     // Another uncaught exception was thrown while handling the first one.
     // If we are displaying errors, then do so with no possibility of a further uncaught exception being thrown.
-    $error_level = variable_get('error_level', ERROR_REPORTING_DISPLAY_ALL);
-    if ($error_level == ERROR_REPORTING_DISPLAY_ALL || (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update')) {
-      print 'Additional uncaught exception thrown while handling exception.<br /><br />';
-      print '<b>Original</b><br />' . _drupal_render_exception_safe($exception) . '<br /><br />';
-      print '<b>Additional</b><br />' . _drupal_render_exception_safe($exception2) . '<br /><br />';
+    if (error_displayable()) {
+      print '<h1>Additional uncaught exception thrown while handling exception.</h1>';
+      print '<h2>Original</h2><p>' . _drupal_render_exception_safe($exception) . '</p>';
+      print '<h2>Additional</h2><p>' . _drupal_render_exception_safe($exception2) . '</p><hr />';
     }
   }
 }
@@ -2963,11 +2962,10 @@ function _drupal_shutdown_function() {
   }
   catch (Exception $exception) {
     // If we are displaying errors, then do so with no possibility of a further uncaught exception being thrown.
-    $error_level = variable_get('error_level', ERROR_REPORTING_DISPLAY_ALL);
-    if ($error_level == ERROR_REPORTING_DISPLAY_ALL || (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update')) {
-      require_once DRUPAL_ROOT . '/includes/errors.inc';
-      print 'Uncaught exception thrown in shutdown function.<br /><br />';
-      print _drupal_render_exception_safe($exception) . '<br /><br />';
+   require_once DRUPAL_ROOT . '/includes/errors.inc';
+   if (error_displayable()) {
+      print '<h1>Uncaught exception thrown in shutdown function.</h1>';
+      print '<p>' . _drupal_render_exception_safe($exception) . '</p><hr />';
     }
   }
 }

includes/errors.inc

@@ -138,6 +138,29 @@ function _drupal_render_exception_safe($exception) {
   return strtr('%type: %message in %function (line %line of %file).', _drupal_decode_exception($exception));
 }
 
+/**
+ * Determines whether an error should be displayed.
+ *
+ * When in maintenance mode or when error_level is ERROR_REPORTING_DISPLAY_ALL,
+ * all errors should be displayed. For ERROR_REPORTING_DISPLAY_SOME, $error
+ * will be examined to determine if it should be displayed.
+ *
+ * @param $error
+ *   Optional error to examine for ERROR_REPORTING_DISPLAY_SOME.
+ *
+ * @return
+ *   TRUE if an error should be displayed.
+ */
+function error_displayable($error = NULL) {
+  $error_level = variable_get('error_level', ERROR_REPORTING_DISPLAY_ALL);
+  $updating = (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update');
+  $all_errors_displayed = ($error_level == ERROR_REPORTING_DISPLAY_ALL);
+  $error_needs_display = ($error_level == ERROR_REPORTING_DISPLAY_SOME &&
+    isset($error) && $error['%type'] != 'Notice' && $error['%type'] != 'Strict warning');
+
+  return ($updating || $all_errors_displayed || $error_needs_display);
+}
+
 /**
  * Log a PHP error or exception, display an error page in fatal cases.
  *
@@ -200,9 +223,7 @@ function _drupal_log_error($error, $fatal = FALSE) {
   else {
     // Display the message if the current error reporting level allows this type
     // of message to be displayed, and unconditionnaly in update.php.
-    $error_level = variable_get('error_level', ERROR_REPORTING_DISPLAY_ALL);
-    $display_error = $error_level == ERROR_REPORTING_DISPLAY_ALL || ($error_level == ERROR_REPORTING_DISPLAY_SOME && $error['%type'] != 'Notice' && $error['%type'] != 'Strict warning');
-    if ($display_error || (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update')) {
+    if (error_displayable($error)) {
       $class = 'error';
 
       // If error type is 'User notice' then treat it as debug information

includes/session.inc

@@ -140,46 +140,58 @@ function _drupal_session_read($sid) {
 function _drupal_session_write($sid, $value) {
   global $user, $is_https;
 
-  if (!drupal_save_session()) {
-    // We don't have anything to do if we are not allowed to save the session.
-    return;
-  }
-
-  $fields = array(
-    'uid' => $user->uid,
-    'cache' => isset($user->cache) ? $user->cache : 0,
-    'hostname' => ip_address(),
-    'session' => $value,
-    'timestamp' => REQUEST_TIME,
-  );
-  $key = array('sid' => $sid);
-  if ($is_https) {
-    $key['ssid'] = $sid;
-    $insecure_session_name = substr(session_name(), 1);
-    // The "secure pages" setting allows a site to simultaneously use both
-    // secure and insecure session cookies. If enabled, use the insecure session
-    // identifier as the sid.
-    if (variable_get('https', FALSE) && isset($_COOKIE[$insecure_session_name])) {
-      $key['sid'] = $_COOKIE[$insecure_session_name];
+  // The exception handler is not active at this point, so we need to do it manually.
+  try {
+    if (!drupal_save_session()) {
+      // We don't have anything to do if we are not allowed to save the session.
+      return;
     }
-  }
-  db_merge('sessions')
-    ->key($key)
-    ->fields($fields)
-    ->execute();
 
-  // Last access time is updated no more frequently than once every 180 seconds.
-  // This reduces contention in the users table.
-  if ($user->uid && REQUEST_TIME - $user->access > variable_get('session_write_interval', 180)) {
-    db_update('users')
-      ->fields(array(
-        'access' => REQUEST_TIME
-      ))
-      ->condition('uid', $user->uid)
+    $fields = array(
+      'uid' => $user->uid,
+      'cache' => isset($user->cache) ? $user->cache : 0,
+      'hostname' => ip_address(),
+      'session' => $value,
+      'timestamp' => REQUEST_TIME,
+    );
+    $key = array('sid' => $sid);
+    if ($is_https) {
+      $key['ssid'] = $sid;
+      $insecure_session_name = substr(session_name(), 1);
+      // The "secure pages" setting allows a site to simultaneously use both
+      // secure and insecure session cookies. If enabled, use the insecure session
+      // identifier as the sid.
+      if (variable_get('https', FALSE) && isset($_COOKIE[$insecure_session_name])) {
+        $key['sid'] = $_COOKIE[$insecure_session_name];
+      }
+    }
+    db_merge('sessions')
+      ->key($key)
+      ->fields($fields)
       ->execute();
-  }
 
-  return TRUE;
+    // Last access time is updated no more frequently than once every 180 seconds.
+    // This reduces contention in the users table.
+    if ($user->uid && REQUEST_TIME - $user->access > variable_get('session_write_interval', 180)) {
+      db_update('users')
+        ->fields(array(
+          'access' => REQUEST_TIME
+        ))
+        ->condition('uid', $user->uid)
+        ->execute();
+    }
+
+    return TRUE;
+  }
+  catch (Exception $exception) {
+    require_once DRUPAL_ROOT . '/includes/errors.inc';
+    // If we are displaying errors, then do so with no possibility of a further uncaught exception being thrown.
+    if (error_displayable()) {
+      print '<h1>Uncaught exception thrown in session handler.</h1>';
+      print '<p>' . _drupal_render_exception_safe($exception) . '</p><hr />';
+    }
+    return FALSE;
+  }
 }
 
 /**