MDL-82658 mod_forum: calculate maxbytes correctly in reply handler.

mod/forum/classes/message/inbound/reply_handler.php

@@ -67,7 +67,7 @@ public function get_name() {
      * @return bool Whether the message was successfully processed.
      */
     public function process_message(\stdClass $record, \stdClass $messagedata) {
-        global $DB, $USER;
+        global $CFG, $DB, $USER;
 
         // Load the post being replied to.
         $post = $DB->get_record('forum_posts', array('id' => $record->datavalue));
@@ -214,13 +214,13 @@ public function process_message(\stdClass $record, \stdClass $messagedata) {
                 $filesize += $attachment->filesize;
             }
 
-            if ($forum->maxbytes < $filesize) {
+            $maxbytes = get_user_max_upload_file_size($modcontext, $CFG->maxbytes, $course->maxbytes, $forum->maxbytes);
+            if ($maxbytes < $filesize) {
                 // Too many attachments.
-                mtrace("--> User attached {$filesize} bytes of files when only {$forum->maxbytes} where allowed. "
-                     . "Rejecting e-mail.");
+                mtrace("--> User attached {$filesize} bytes of files when only {$maxbytes} were allowed. Rejecting e-mail.");
                 $data = new \stdClass();
                 $data->forum = $forum;
-                $data->maxbytes = display_size($forum->maxbytes, 0);
+                $data->maxbytes = display_size($maxbytes);
                 $data->filesize = display_size($filesize);
                 throw new \core\message\inbound\processing_failed_exception('messageinboundfilesizeexceeded', 'mod_forum', $data);
             }

mod/forum/tests/message/inbound/reply_handler_test.php

@@ -0,0 +1,170 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace mod_forum\message\inbound;
+
+use advanced_testcase;
+use core\context\module;
+use core\message\inbound\{manager, processing_failed_exception};
+use mod_forum_generator;
+use stdClass;
+use Throwable;
+
+/**
+ * Unit tests for the reply handler
+ *
+ * @package     mod_forum
+ * @covers      \mod_forum\message\inbound\reply_handler
+ * @copyright   2024 Paul Holden <[email protected]>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+final class reply_handler_test extends advanced_testcase {
+
+    /**
+     * Test attachment processing
+     */
+    public function test_process_message_attachments(): void {
+        global $DB;
+
+        $this->resetAfterTest();
+
+        $course = $this->getDataGenerator()->create_course(['maxbytes' => 1024]);
+        $forum = $this->getDataGenerator()->create_module('forum', ['course' => $course->id, 'maxbytes' => 0]);
+
+        $user = $this->getDataGenerator()->create_and_enrol($course);
+        $this->setUser($user);
+
+        [$discussion, $post] = $this->create_discussion_with_post($forum, $user);
+
+        $output = $this->reply_handler_process_message($post, 'My reply', 'Hello', (object) [
+            'filename' => 'Foo.txt',
+            'content' => 'Foo',
+            'filesize' => 3,
+        ]);
+
+        $this->assertMatchesRegularExpression('/Processing Foo.txt as an attachment./', $output);
+        $this->assertMatchesRegularExpression('/Attaching Foo.txt to/', $output);
+        $this->assertMatchesRegularExpression('/Created a post \d+ in \d+./', $output);
+
+        // Assert our reply was added with attachment.
+        $newpost = $DB->get_record('forum_posts', [
+            'discussion' => $discussion->id,
+            'subject' => 'My reply',
+            'attachment' => 1,
+        ], '*', MUST_EXIST);
+
+        $attachments = get_file_storage()->get_area_files(
+            module::instance($forum->cmid)->id,
+            'mod_forum',
+            'attachment',
+            $newpost->id,
+            'id',
+            false,
+        );
+        $this->assertCount(1, $attachments);
+        $this->assertEquals('Foo.txt', reset($attachments)->get_filename());
+    }
+
+    /**
+     * Test attachment processing where maxbytes is exceeded
+     */
+    public function test_process_message_attachments_over_maxbytes(): void {
+        $this->resetAfterTest();
+
+        $course = $this->getDataGenerator()->create_course();
+        $forum = $this->getDataGenerator()->create_module('forum', ['course' => $course->id, 'maxbytes' => 2]);
+
+        $user = $this->getDataGenerator()->create_and_enrol($course);
+        $this->setUser($user);
+
+        [$discussion, $post] = $this->create_discussion_with_post($forum, $user);
+
+        $this->expectException(processing_failed_exception::class);
+        $this->expectExceptionMessage('Unable to post your reply, since the total attachment size (3 bytes) is greater than ' .
+            'the maximum size allowed for the forum (2 bytes)');
+        $this->reply_handler_process_message($post, 'My reply', 'Hello', (object) [
+            'filename' => 'Foo.txt',
+            'content' => 'Foo',
+            'filesize' => 3,
+        ]);
+    }
+
+    /**
+     * Helper to generate discussion/post data
+     *
+     * @param stdClass $forum
+     * @param stdClass $user
+     * @return stdClass[]
+     */
+    private function create_discussion_with_post(stdClass $forum, stdClass $user): array {
+        /** @var mod_forum_generator $generator */
+        $generator = $this->getDataGenerator()->get_plugin_generator('mod_forum');
+
+        $discussion = $generator->create_discussion(['course' => $forum->course, 'forum' => $forum->id, 'userid' => $user->id]);
+        $post = $generator->create_post(['discussion' => $discussion->id, 'userid' => $user->id]);
+
+        return [$discussion, $post];
+    }
+
+    /**
+     * Helper to process message details using the reply handler
+     *
+     * @param stdClass $post
+     * @param string $subject
+     * @param string $message
+     * @param stdClass $attachment
+     * @return string Output buffer from the handler
+     */
+    private function reply_handler_process_message(
+        stdClass $post,
+        string $subject,
+        string $message,
+        stdClass $attachment,
+    ): string {
+
+        // Start capturing output.
+        ob_start();
+
+        /** @var reply_handler $handler */
+        $handler = manager::get_handler(reply_handler::class);
+
+        try {
+            $handler->process_message(
+                (object) [
+                    'datavalue' => $post->id,
+                ],
+                (object) [
+                    'envelope' => (object) [
+                        'subject' => $subject,
+                    ],
+                    'plain' => $message,
+                    'attachments' => [
+                        'attachment' => [
+                            $attachment,
+                        ],
+                    ],
+                    'timestamp' => time(),
+                ],
+            );
+        } catch (Throwable $ex) {
+            ob_end_clean();
+            throw $ex;
+        }
+
+        // Return captured output buffer.
+        return (string) ob_get_clean();
+    }
+}