Bug#27167197 USING ? IN INSTALL PLUGIN QUERY ABORTS DEBUG, AND HANGS OPTIMIZED SERVER

check_valid_path() uses my_strcspn() that cannot handle invalid characters
properly. This is fixed by a big refactoring in 10.2 (MDEV-6353).

For 5.5, let's simply swap tests, because check_string_char_length()
rejects invalid characters just fine.

mysql-test/r/plugin.result

@@ -277,5 +277,13 @@ UNUSABLE
 uninstall soname 'ha_example';
 select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
 plugin_name
+set names utf8;
+select convert('admin𝌆' using utf8);
+convert('admin𝌆' using utf8)
+admin
+Warnings:
+Warning	1300	Invalid utf8 character string: 'F09D8C'
+install plugin foo soname 'admin𝌆';
+ERROR HY000: No paths allowed for shared library
 insert mysql.plugin values ();
 delete from mysql.plugin where name = '';

mysql-test/t/plugin.test

@@ -224,9 +224,18 @@ select plugin_name from information_schema.plugins where plugin_library like 'ha
 uninstall soname 'ha_example';
 select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
 
+#
+#
+#
+set names utf8;
+select convert('admin𝌆' using utf8);
+--error ER_UDF_NO_PATHS
+install plugin foo soname 'admin𝌆';
+
 #
 # Bug#27302459: EMPTY VALUE IN MYSQL.PLUGIN TABLE CAUSES SERVER TO EXIT ON STARTUP
 #
 insert mysql.plugin values ();
 source include/restart_mysqld.inc;
 delete from mysql.plugin where name = '';
+

sql/sql_plugin.cc

@@ -736,9 +736,9 @@ static st_plugin_dl *plugin_dl_add(const LEX_STRING *dl, int report)
     This is done to ensure that only approved libraries from the
     plugin directory are used (to make this even remotely secure).
   */
-  if (check_valid_path(dl->str, dl->length) ||
-      check_string_char_length((LEX_STRING *) dl, "", NAME_CHAR_LEN,
+  if (check_string_char_length((LEX_STRING *) dl, "", NAME_CHAR_LEN,
                                system_charset_info, 1) ||
+      check_valid_path(dl->str, dl->length) ||
       plugin_dir_len + dl->length + 1 >= FN_REFLEN)
   {
     report_error(report, ER_UDF_NO_PATHS);