tests for feedback plugin,

bugfix: garbage in PLUGIN_VAR_STR variables when INSTALL'ing a plugin

mysql-test/include/default_mysqld.cnf:
  disable feedback plugin by default.
  when enabled - tag is as a test run

mysql-test/include/default_mysqld.cnf

@@ -15,6 +15,8 @@ max_heap_table_size=        1M
 
 loose-skip-innodb
 loose-skip-pbxt
+loose-skip-feedback
+loose-feedback-user-info=  mysql-test
 
 loose-innodb_data_file_path=      ibdata1:10M:autoextend
 

mysql-test/r/feedback_plugin_install.result

+install plugin feedback soname 'feedback.so';
+select plugin_status from information_schema.plugins where plugin_name='feedback';
+plugin_status
+ACTIVE
+select * from information_schema.feedback where variable_name like 'feed%'
+       and variable_name not like  '%_uid';
+VARIABLE_NAME	VARIABLE_VALUE
+FEEDBACK_SEND_RETRY_WAIT	60
+FEEDBACK_USER_INFO	mysql-test
+FEEDBACK_SEND_TIMEOUT	60
+FEEDBACK_URL	http://mariadb.org/feedback_plugin/post
+FEEDBACK	1.0
+uninstall plugin feedback;

mysql-test/r/feedback_plugin_load.result

+select plugin_status from information_schema.plugins where plugin_name='feedback';
+plugin_status
+ACTIVE
+select * from information_schema.feedback where variable_name like 'feed%'
+       and variable_name not like  '%_uid';
+VARIABLE_NAME	VARIABLE_VALUE
+FEEDBACK_SEND_RETRY_WAIT	60
+FEEDBACK_USER_INFO	mysql-test
+FEEDBACK_SEND_TIMEOUT	60
+FEEDBACK_URL	http://mariadb.org/feedback_plugin/post
+FEEDBACK	1.0

mysql-test/r/feedback_plugin_send.result

+select plugin_status from information_schema.plugins where plugin_name='feedback';
+plugin_status
+ACTIVE
+select * from information_schema.feedback where variable_name like 'feed%'
+       and variable_name not like  '%_uid';
+VARIABLE_NAME	VARIABLE_VALUE
+FEEDBACK_SEND_RETRY_WAIT	60
+FEEDBACK_USER_INFO	mysql-test
+FEEDBACK_SEND_TIMEOUT	60
+FEEDBACK_URL	http://mariadb.org/feedback_plugin/post
+FEEDBACK	1.0
+feedback plugin: report to 'http://mariadb.org/feedback_plugin/post' was sent
+feedback plugin: server replied 'ok'
+feedback plugin: report to 'http://mariadb.org/feedback_plugin/post' was sent
+feedback plugin: server replied 'ok'

mysql-test/t/feedback_plugin_install.opt

+--loose-feedback

mysql-test/t/feedback_plugin_install.test

+--source include/not_embedded.inc
+
+if (`select length('$FEEDBACK_SO') = 0`) {
+  skip No feedback plugin;
+}
+
+--replace_regex /\.dll/.so/
+eval install plugin feedback soname '$FEEDBACK_SO';
+select plugin_status from information_schema.plugins where plugin_name='feedback';
+--replace_result https http
+select * from information_schema.feedback where variable_name like 'feed%'
+       and variable_name not like  '%_uid';
+uninstall plugin feedback;
+

mysql-test/t/feedback_plugin_load.opt

+--loose-feedback
+--plugin-load=$FEEDBACK_SO

mysql-test/t/feedback_plugin_load.test

+if (`select count(*) = 0 from information_schema.plugins where plugin_name = 'feedback' and plugin_status='active'`)
+{
+  --skip Feedback plugin is not active
+}
+
+select plugin_status from information_schema.plugins where plugin_name='feedback';
+--replace_result https http
+select * from information_schema.feedback where variable_name like 'feed%'
+       and variable_name not like  '%_uid';

mysql-test/t/feedback_plugin_send.test

+source t/feedback_plugin_load.test;
+source include/big_test.inc;
+
+if (!$MTR_FEEDBACK_PLUGIN) {
+  skip MTR_FEEDBACK_PLUGIN is not set;
+}
+
+#
+# Yep. The plugin waits 5 minutes before sending anything,
+# and there's no way to force it to send anything sooner.
+# Let's wait, and hope that mtr is started with --parallel and
+# is doing some work in other workers.
+#
+sleep 310;
+source include/restart_mysqld.inc;
+
+replace_result https http;
+perl;
+  $log_error= $ENV{'MYSQLTEST_VARDIR'} . '/log/mysqld.1.err';
+  open(LOG, '<', $log_error) or die "open(< $log_error): $!";
+  /feedback plugin:.*/ && print "$&\n" while $_=<LOG>;
+  close LOG;
+EOF
+

sql/sql_plugin.cc

@@ -3176,6 +3176,19 @@ static int construct_options(MEM_ROOT *mem_root, struct st_plugin_int *tmp,
                             opt->name, plugin_name);
         }
       }
+      /*
+        PLUGIN_VAR_STR command-line options without PLUGIN_VAR_MEMALLOC, point
+        directly to values in the argv[] array. For plugins started at the
+        server startup, argv[] array is allocated with load_defaults(), and
+        freed when the server is shut down.  But for plugins loaded with
+        INSTALL PLUGIN, the memory allocated with load_defaults() is freed with
+        freed() at the end of mysql_install_plugin(). Which means we cannot
+        allow any pointers into that area.
+        Thus, for all plugins loaded after the server was started,
+        we force all command-line options to be PLUGIN_VAR_MEMALLOC
+      */
+      if (mysqld_server_started && !(opt->flags & PLUGIN_VAR_NOCMDOPT))
+        opt->flags|= PLUGIN_VAR_MEMALLOC;
       break;
     case PLUGIN_VAR_ENUM:
       if (!opt->check)