From 076e09b195160db3d8dc4602bd5b1efbfb5d9868 Mon Sep 17 00:00:00 2001
From: Yip Rui Fung <rf@yrf.me>
Date: Thu, 4 Feb 2021 19:59:45 +0800
Subject: [PATCH] Prevent user from being able to override the collate /
 charset table creation options.

Bad things would probably happen if they changed it to something that isn't some kind of unicode encoding.

Signed-off-by: Yip Rui Fung <rf@yrf.me>
---
 config/config.sample.php             | 11 +++++------
 lib/private/DB/ConnectionFactory.php | 29 +++++++++++++++++++++-------
 2 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/config/config.sample.php b/config/config.sample.php
index 7aaa98f831..a4c12a1376 100644
--- a/config/config.sample.php
+++ b/config/config.sample.php
@@ -1513,18 +1513,17 @@ $CONFIG = [
 'mysql.utf8mb4' => false,
 
 /**
- * This configuration parameter can be used to override the default options used for table creation.
- * This parameter will take precedence over mysql.utf8mb4 if that is set to true.
+ * This configuration parameter can be used to add or change the default options used for table creation.
+ * For changing charset / collation see mysql.utf8mb4
  *
  * An example use for this parameter is where MariaDB page compression is enabled by default as the
  * COMPRESSED row format is not allowed there, and thus table creation will fail.
- * This option can then be used to override this and change/remove the row_format option.
+ * This option can then be used to override this and change the row_format option.
  *
  */
 'dbdefaulttableoptions' => [
-	'collate' => 'utf8mb4_bin',
-	'charset' => 'utf8mb4',
-	'row_format' => 'compressed'
+	'row_format' => 'dynamic',
+	'page_compressed' => '1'
 ],
 
 /**
diff --git a/lib/private/DB/ConnectionFactory.php b/lib/private/DB/ConnectionFactory.php
index 4ba606f5dd..9ed8b87747 100644
--- a/lib/private/DB/ConnectionFactory.php
+++ b/lib/private/DB/ConnectionFactory.php
@@ -216,19 +216,34 @@ class ConnectionFactory {
 		}
 
 		// set default table creation options
-		$connectionParams['defaultTableOptions'] = $this->config->getValue('dbdefaulttableoptions', [
-			'collate' => 'utf8_bin'
-		]);
+		$defaultTableOptions = [
+			'collate' => 'utf8_bin',
+			'tablePrefix' => $connectionParams['tablePrefix']
+		];
 
-		if ($this->config->getValue('mysql.utf8mb4', false) && is_null($this->config->getValue('dbdefaulttableoptions'))) {
-			$connectionParams['defaultTableOptions'] = [
+		if ($this->config->getValue('mysql.utf8mb4', false)) {
+			$defaultTableOptions = [
 				'collate' => 'utf8mb4_bin',
 				'charset' => 'utf8mb4',
-				'row_format' => 'compressed'
+				'row_format' => 'compressed',
+				'tablePrefix' => $connectionParams['tablePrefix']
 			];
 		}
 
-		$connectionParams['defaultTableOptions']['tablePrefix'] = $connectionParams['tablePrefix'];
+		$configTableOptions = $this->config->getValue('dbdefaulttableoptions', []);
+
+		// prevent user from overriding collation / charset and tablePrefix here (previous behavior.)
+		if (array_key_exists('collate', $configTableOptions)) {
+			unset($configTableOptions['collate']);
+		}
+		if (array_key_exists('charset', $configTableOptions)) {
+			unset($configTableOptions['charset']);
+		}
+		if (array_key_exists('tablePrefix', $configTableOptions)) {
+			unset($configTableOptions['tablePrefix']);
+		}
+
+		$connectionParams['defaultTableOptions'] = array_merge($defaultTableOptions, $configTableOptions);
 
 		return $connectionParams;
 	}