From 9df4ae4189398b5d7b46b72b9cbbe942f2cef255 Mon Sep 17 00:00:00 2001
From: David Monllao <davidm@moodle.com>
Date: Thu, 21 Apr 2016 14:47:09 +0800
Subject: [PATCH] MDL-51603 dataformats: coding_exception if output buffering

---
 lib/dataformatlib.php | 4 ++--
 lib/tablelib.php      | 6 ++----
 lib/upgrade.txt       | 1 +
 report/log/index.php  | 4 ----
 4 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/lib/dataformatlib.php b/lib/dataformatlib.php
index f192ef82d44..36b51731002 100644
--- a/lib/dataformatlib.php
+++ b/lib/dataformatlib.php
@@ -38,8 +38,8 @@
  */
 function download_as_dataformat($filename, $dataformat, $columns, $iterator, $callback = null) {
 
-    if (!NO_OUTPUT_BUFFERING) {
-        throw new coding_exception("NO_OUTPUT_BUFFERING must be set to true before calling download_as_dataformat");
+    if (ob_get_length()) {
+        throw new coding_exception("Output can not be buffered before calling download_as_dataformat");
     }
 
     $classname = 'dataformat_' . $dataformat . '\writer';
diff --git a/lib/tablelib.php b/lib/tablelib.php
index d33942c3ce1..ce3ff202fe5 100644
--- a/lib/tablelib.php
+++ b/lib/tablelib.php
@@ -1704,10 +1704,8 @@ class table_dataformat_export_format extends table_default_export_format_parent
     public function __construct(&$table, $dataformat) {
         parent::__construct($table);
 
-        if (!NO_OUTPUT_BUFFERING) {
-            // Ideally this would throw a coding exception but we are more forgiving here due
-            // to the large amount of code already using table_sql.
-            debugging("NO_OUTPUT_BUFFERING should be set to true before downloading", DEBUG_DEVELOPER);
+        if (ob_get_length()) {
+            throw new coding_exception("Output can not be buffered before instantiating table_dataformat_export_format");
         }
 
         $classname = 'dataformat_' . $dataformat . '\writer';
diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index 172d9c2eab7..c9129594734 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -116,6 +116,7 @@ information provided here is intended especially for developers.
 * behat_util::is_server_running() is removed, please use behat_util::check_server_status() instead.
 * Behat\Mink\Selector\SelectorsHandler::xpathLiteral() method is deprecated use behat_context_helper::escape instead
   when building Xpath, or pass the unescaped value when using the named selector.',
+* table_sql download process is using the new data formats plugin which you can't use if you are buffering any output
 
 === 3.0 ===
 
diff --git a/report/log/index.php b/report/log/index.php
index 79bcff15520..d5e00ee29df 100644
--- a/report/log/index.php
+++ b/report/log/index.php
@@ -22,10 +22,6 @@
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
-if (!empty($_GET['download'])) {
-    define('NO_OUTPUT_BUFFERING', true);
-}
-
 require('../../config.php');
 require_once($CFG->dirroot.'/course/lib.php');
 require_once($CFG->dirroot.'/report/log/locallib.php');