From ff2ec2cb95b2cd673dcb199c0e7c45dc58516bef Mon Sep 17 00:00:00 2001
From: Tim Hunt <T.J.Hunt@open.ac.uk>
Date: Fri, 27 Jul 2012 11:42:03 +0100
Subject: [PATCH] MDL-34599 quiz attempts: more robust if page number out of
 range.

Rather than throwing an exception, we should just show the first/last
page of the quiz if the page number is out-of-range.
---
 mod/quiz/attempt.php        |  1 +
 mod/quiz/attemptlib.php     | 12 +++++++++++-
 mod/quiz/processattempt.php | 12 ++++++------
 mod/quiz/review.php         |  5 +++--
 4 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/mod/quiz/attempt.php b/mod/quiz/attempt.php
index 162e67262a7..a24245dd215 100644
--- a/mod/quiz/attempt.php
+++ b/mod/quiz/attempt.php
@@ -41,6 +41,7 @@ $attemptid = required_param('attempt', PARAM_INT);
 $page = optional_param('page', 0, PARAM_INT);
 
 $attemptobj = quiz_attempt::create($attemptid);
+$page = $attemptobj->force_page_number_into_range($page);
 $PAGE->set_url($attemptobj->attempt_url(null, $page));
 
 // Check login.
diff --git a/mod/quiz/attemptlib.php b/mod/quiz/attemptlib.php
index 78a74a61307..7d6b7965df1 100644
--- a/mod/quiz/attemptlib.php
+++ b/mod/quiz/attemptlib.php
@@ -555,6 +555,16 @@ class quiz_attempt {
         }
     }
 
+    /**
+     * If the given page number is out of range (before the first page, or after
+     * the last page, chnage it to be within range).
+     * @param int $page the requested page number.
+     * @return int a safe page number to use.
+     */
+    public function force_page_number_into_range($page) {
+        return min(max($page, 0), count($this->pagelayout) - 1);
+    }
+
     // Simple getters ==========================================================
     public function get_quiz() {
         return $this->quizobj->get_quiz();
@@ -1101,7 +1111,7 @@ class quiz_attempt {
     }
 
     /**
-     * Initialise the JS etc. required all the questions on a page..
+     * Initialise the JS etc. required all the questions on a page.
      * @param mixed $page a page number, or 'all'.
      */
     public function get_html_head_contributions($page = 'all', $showall = false) {
diff --git a/mod/quiz/processattempt.php b/mod/quiz/processattempt.php
index 1757eb5db41..9f391f04ecf 100644
--- a/mod/quiz/processattempt.php
+++ b/mod/quiz/processattempt.php
@@ -37,13 +37,13 @@ require_once($CFG->dirroot . '/mod/quiz/locallib.php');
 $timenow = time();
 
 // Get submitted parameters.
-$attemptid = required_param('attempt', PARAM_INT);
-$next = optional_param('next', false, PARAM_BOOL);
-$thispage = optional_param('thispage', 0, PARAM_INT);
-$nextpage = optional_param('nextpage', 0, PARAM_INT);
+$attemptid     = required_param('attempt',  PARAM_INT);
+$thispage      = required_param('thispage', PARAM_INT);
+$nextpage      = required_param('nextpage', PARAM_INT);
+$next          = optional_param('next',          false, PARAM_BOOL);
 $finishattempt = optional_param('finishattempt', false, PARAM_BOOL);
-$timeup = optional_param('timeup', 0, PARAM_BOOL); // True if form was submitted by timer.
-$scrollpos = optional_param('scrollpos', '', PARAM_RAW);
+$timeup        = optional_param('timeup',        0,      PARAM_BOOL); // True if form was submitted by timer.
+$scrollpos     = optional_param('scrollpos',     '',     PARAM_RAW);
 
 $transaction = $DB->start_delegated_transaction();
 $attemptobj = quiz_attempt::create($attemptid);
diff --git a/mod/quiz/review.php b/mod/quiz/review.php
index 7bb6335d8fe..c19afaa8970 100644
--- a/mod/quiz/review.php
+++ b/mod/quiz/review.php
@@ -31,8 +31,8 @@ require_once($CFG->dirroot . '/mod/quiz/locallib.php');
 require_once($CFG->dirroot . '/mod/quiz/report/reportlib.php');
 
 $attemptid = required_param('attempt', PARAM_INT);
-$page = optional_param('page', 0, PARAM_INT);
-$showall = optional_param('showall', 0, PARAM_BOOL);
+$page      = optional_param('page', 0, PARAM_INT);
+$showall   = optional_param('showall', 0, PARAM_BOOL);
 
 $url = new moodle_url('/mod/quiz/review.php', array('attempt'=>$attemptid));
 if ($page !== 0) {
@@ -44,6 +44,7 @@ if ($showall !== 0) {
 $PAGE->set_url($url);
 
 $attemptobj = quiz_attempt::create($attemptid);
+$page = $attemptobj->force_page_number_into_range($page);
 
 // Check login.
 require_login($attemptobj->get_course(), false, $attemptobj->get_cm());