Fail if ini_set/ini_get are disabled

We might support operation without these two later, but it's quite a lot
of work and nobody was really requesting this.

Fixes #13471

Signed-off-by: Michal Čihař <michal@cihar.com>

ChangeLog

@@ -12,6 +12,7 @@ phpMyAdmin - ChangeLog
 - issue #13382 Fixed size of index edit dialog
 - issue #13489 Fixed rendering SQL lint errors
 - issue #13468 Avoid breakage if set_time_limit is disabled
+- issue #13471 Fail if ini_set/ini_get are disabled
 
 4.7.2 (2017-06-29)
 - issue #13314 Make theme selection keep current server

libraries/common.inc.php

@@ -474,6 +474,19 @@ if (@extension_loaded('mbstring') && !empty(@ini_get('mbstring.func_overload')))
     );
 }
 
+/**
+ * The ini_set and ini_get functions can be disabled using
+ * disable_functions but we're relying quite a lot of them.
+ */
+if (! function_exists('ini_get') || ! function_exists('ini_set')) {
+    PMA_fatalError(
+        __(
+            'You have disabled ini_get and/or ini_set in php.ini. '
+            . 'This option is incompatible with phpMyAdmin!'
+        )
+    );
+}
+
 /******************************************************************************/
 /* setup servers                                       LABEL_setup_servers    */