MDL-15494 - No allowance for the possibility that something might go wrong when processing the response to a question. Backported from HEAD.

lang/en_utf8/question.php

@@ -37,6 +37,7 @@ $string['errorfilecannotbemoved'] = 'Error cannot move file $a.';
 $string['errorfileschanged'] = 'Error files linked to from questions have changed since form was displayed.';
 $string['errormanualgradeoutofrange'] = 'The grade $a->grade is not between 0 and $a->maxgrade for question $a->name. The score and comment have not been saved.';
 $string['errormovingquestions'] = 'Error while moving questions with ids $a.';
+$string['errorprocessingresponses'] = 'An error occurred while processing your responses.';
 $string['errorsavingcomment'] = 'Error saving the comment for question $a->name in the database.';
 $string['errorupdatingattempt'] = 'Error updating attempt $a->id in the database.';
 $string['exportcategory'] = 'Export category';

lib/questionlib.php

@@ -1268,7 +1268,6 @@ function regrade_question_in_attempt($question, $attempt, $cmoptions, $verbose=f
 /**
 * Processes an array of student responses, grading and saving them as appropriate
 *
-* @return boolean         Indicates success/failure
 * @param object $question Full question object, passed by reference
 * @param object $state    Full state object, passed by reference
 * @param object $action   object with the fields ->responses which
@@ -1279,6 +1278,7 @@ function regrade_question_in_attempt($question, $attempt, $cmoptions, $verbose=f
 * @param object $cmoptions
 * @param object $attempt  The attempt is passed by reference so that
 *                         during grading its ->sumgrades field can be updated
+* @return boolean         Indicates success/failure
 */
 function question_process_responses(&$question, &$state, $action, $cmoptions, &$attempt) {
     global $QTYPES;
@@ -1339,7 +1339,9 @@ function question_process_responses(&$question, &$state, $action, $cmoptions, &$
 
     if (!question_isgradingevent($action->event)) {
         // Grade the response but don't update the overall grade
-        $QTYPES[$question->qtype]->grade_responses($question, $state, $cmoptions);
+        if (!$QTYPES[$question->qtype]->grade_responses($question, $state, $cmoptions)) {
+            return false;
+        }
 
         // Temporary hack because question types are not given enough control over what is going
         // on. Used by Opaque questions.
@@ -1375,8 +1377,10 @@ function question_process_responses(&$question, &$state, $action, $cmoptions, &$
         // If we did not find a duplicate or if the attempt is closing, perform grading
         if ((!$sameresponses and QUESTION_EVENTDUPLICATE != $state->event) or
                 QUESTION_EVENTCLOSE == $action->event) {
+            if (!$QTYPES[$question->qtype]->grade_responses($question, $state, $cmoptions)) {
+                return false;
+            }
 
-            $QTYPES[$question->qtype]->grade_responses($question, $state, $cmoptions);
             // Calculate overall grade using correct penalty method
             question_apply_penalty_and_timelimit($question, $state, $attempt, $cmoptions);
         }

mod/quiz/attempt.php

@@ -303,14 +303,27 @@
         // Process each question in turn
 
         $questionidarray = explode(',', $questionids);
+        $success = true;
         foreach($questionidarray as $i) {
             if (!isset($actions[$i])) {
                 $actions[$i]->responses = array('' => '');
                 $actions[$i]->event = QUESTION_EVENTOPEN;
             }
             $actions[$i]->timestamp = $timestamp;
-            question_process_responses($questions[$i], $states[$i], $actions[$i], $quiz, $attempt);
-            save_question_session($questions[$i], $states[$i]);
+            if (question_process_responses($questions[$i], $states[$i], $actions[$i], $quiz, $attempt)) {
+                save_question_session($questions[$i], $states[$i]);
+            } else {
+                $success = false;
+            }
+        }
+
+        if (!$success) {
+            $pagebit = '';
+            if ($page) {
+                $pagebit = '&page=' . $page;
+            }
+            print_error('errorprocessingresponses', 'question',
+                    $CFG->wwwroot . '/mod/quiz/attempt.php?q=' . $quiz->id . $pagebit);
         }
 
         $attempt->timemodified = $timestamp;
@@ -345,12 +358,26 @@
             error('Could not restore question sessions');
         }
 
+        $success = true;
         foreach($closequestions as $key => $question) {
             $action->event = QUESTION_EVENTCLOSE;
             $action->responses = $closestates[$key]->responses;
             $action->timestamp = $closestates[$key]->timestamp;
-            question_process_responses($question, $closestates[$key], $action, $quiz, $attempt);
-            save_question_session($question, $closestates[$key]);
+            
+            if (question_process_responses($question, $closestates[$key], $action, $quiz, $attempt)) {
+                save_question_session($question, $closestates[$key]);
+            } else {
+                $success = false;
+            }
+        }
+
+        if (!$success) {
+            $pagebit = '';
+            if ($page) {
+                $pagebit = '&page=' . $page;
+            }
+            print_error('errorprocessingresponses', 'question',
+                    $CFG->wwwroot . '/mod/quiz/attempt.php?q=' . $quiz->id . $pagebit);
         }
 
         add_to_log($course->id, 'quiz', 'close attempt',

question/preview.php

@@ -163,7 +163,10 @@
         $event = $finishattempt ? QUESTION_EVENTCLOSE : QUESTION_EVENTSUBMIT;
         if ($actions = question_extract_responses($questions, $form, $event)) {
             $actions[$id]->timestamp = 0; // We do not care about timelimits here
-            question_process_responses($questions[$id], $curstate, $actions[$id], $quiz, $attempt);
+            if (!question_process_responses($questions[$id], $curstate, $actions[$id], $quiz, $attempt)) {
+                unset($SESSION->quizpreview);
+                print_error('errorprocessingresponses', 'question', $url->out());
+            }
             if (!$curstate->changed) {
                 // Update the current state rather than creating a new one
                 $historylength--;

question/type/description/questiontype.php

@@ -87,6 +87,7 @@ class description_qtype extends default_questiontype {
     function grade_responses(&$question, &$state, $cmoptions) {
         $state->raw_grade = 0;
         $state->penalty = 0;
+        return true;
     }
 
 }