Fix for Bug #17544 "Cannot do atomic log rotate",

Bug #21785 "Server crashes after rename of the log table" and
Bug #21966 "Strange warnings on create like/repair of the log
            tables"

According to the patch, from now on, one should use RENAME to
perform a log table rotation (this should also be reflected in
the manual).

Here is a sample:

use mysql;
CREATE TABLE IF NOT EXISTS general_log2 LIKE general_log;
RENAME TABLE general_log TO general_log_backup, general_log2 TO general_log;

The rules for Rename of the log tables are following:
      IF   1. Log tables are enabled
      AND  2. Rename operates on the log table and nothing is being
              renamed to the log table.
      DO   3. Throw an error message.
      ELSE 4. Perform rename.
 
The very RENAME query will go the the old (backup) table. This is
consistent with the behavoiur we have with binlog ROTATE LOGS
statement.

Other problems, which are solved by the patch are:

1) Now REPAIR of the log table is exclusive operation (as it should be), this
   also eliminates lock-related warnings. and
2) CREATE LIKE TABLE now usese usual read lock on the source table rather
   then name lock, which is too restrictive. This way we get rid of another
   log table-related warning, which occured because of the above fact
   (as a side-effect, name lock resulted in a warning).

mysql-test/r/log_tables.result

@@ -218,3 +218,71 @@ unlock tables;
 use mysql;
 lock tables general_log read local, help_category read local;
 unlock tables;
+use mysql;
+RENAME TABLE general_log TO renamed_general_log;
+ERROR HY000: Cannot rename 'general_log'. When logging enabled, rename to/from log table must rename two tables: the log table to an archive table and another table back to 'general_log'
+RENAME TABLE slow_log TO renamed_slow_log;
+ERROR HY000: Cannot rename 'slow_log'. When logging enabled, rename to/from log table must rename two tables: the log table to an archive table and another table back to 'slow_log'
+truncate table general_log;
+select * from general_log;
+event_time	user_host	thread_id	server_id	command_type	argument
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	select * from general_log
+truncate table slow_log;
+select * from slow_log;
+start_time	user_host	query_time	lock_time	rows_sent	rows_examined	db	last_insert_id	insert_id	server_id	sql_text
+create table general_log_new like general_log;
+rename table general_log TO renamed_general_log, general_log_new TO general_log;
+create table slow_log_new like slow_log;
+rename table slow_log TO renamed_slow_log, slow_log_new TO slow_log;
+rename table general_log TO general_log_new, renamed_general_log TO general_log, slow_log to renamed_slow_log;
+ERROR HY000: Cannot rename 'slow_log'. When logging enabled, rename to/from log table must rename two tables: the log table to an archive table and another table back to 'slow_log'
+select * from general_log;
+event_time	user_host	thread_id	server_id	command_type	argument
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	create table slow_log_new like slow_log
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	rename table slow_log TO renamed_slow_log, slow_log_new TO slow_log
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	rename table general_log TO general_log_new, renamed_general_log TO general_log, slow_log to renamed_slow_log
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	select * from general_log
+select * from renamed_general_log;
+event_time	user_host	thread_id	server_id	command_type	argument
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	select * from general_log
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	truncate table slow_log
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	select * from slow_log
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	create table general_log_new like general_log
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	rename table general_log TO renamed_general_log, general_log_new TO general_log
+select * from slow_log;
+start_time	user_host	query_time	lock_time	rows_sent	rows_examined	db	last_insert_id	insert_id	server_id	sql_text
+select * from renamed_slow_log;
+start_time	user_host	query_time	lock_time	rows_sent	rows_examined	db	last_insert_id	insert_id	server_id	sql_text
+set global general_log='OFF';
+RENAME TABLE general_log TO general_log2;
+set global slow_query_log='OFF';
+RENAME TABLE slow_log TO slow_log2;
+set global general_log='ON';
+ERROR HY000: Cannot activate 'general' log
+set global slow_query_log='ON';
+ERROR HY000: Cannot activate 'slow query' log
+RENAME TABLE general_log2 TO general_log;
+RENAME TABLE slow_log2 TO slow_log;
+set global general_log='ON';
+set global slow_query_log='ON';
+flush logs;
+flush logs;
+drop table renamed_general_log, renamed_slow_log;
+use test;
+use mysql;
+repair table general_log;
+Table	Op	Msg_type	Msg_text
+mysql.general_log	repair	status	OK
+repair table slow_log;
+Table	Op	Msg_type	Msg_text
+mysql.slow_log	repair	status	OK
+create table general_log_new like general_log;
+create table slow_log_new like slow_log;
+show tables like "%log%";
+Tables_in_mysql (%log%)
+general_log
+general_log_new
+slow_log
+slow_log_new
+drop table slow_log_new, general_log_new;
+use test;

mysql-test/t/log_tables.test

@@ -314,6 +314,89 @@ use mysql;
 lock tables general_log read local, help_category read local;
 unlock tables;
 
+#
+# Bug #17544 Cannot do atomic log rotate and
+# Bug #21785 Server crashes after rename of the log table
+#
+
+use mysql;
+# Should result in error
+--error ER_CANT_RENAME_LOG_TABLE
+RENAME TABLE general_log TO renamed_general_log;
+--error ER_CANT_RENAME_LOG_TABLE
+RENAME TABLE slow_log TO renamed_slow_log;
+
+#check rotate logs
+truncate table general_log;
+--replace_column 1 TIMESTAMP 2 USER_HOST 3 THREAD_ID
+select * from general_log;
+
+truncate table slow_log;
+--replace_column 1 TIMESTAMP 2 USER_HOST
+select * from slow_log;
+
+create table general_log_new like general_log;
+rename table general_log TO renamed_general_log, general_log_new TO general_log;
+
+create table slow_log_new like slow_log;
+rename table slow_log TO renamed_slow_log, slow_log_new TO slow_log;
+
+# check that rename checks more then first table in the list
+--error ER_CANT_RENAME_LOG_TABLE
+rename table general_log TO general_log_new, renamed_general_log TO general_log, slow_log to renamed_slow_log;
+
+# now check the content of tables
+--replace_column 1 TIMESTAMP 2 USER_HOST 3 THREAD_ID
+select * from general_log;
+--replace_column 1 TIMESTAMP 2 USER_HOST 3 THREAD_ID
+select * from renamed_general_log;
+
+# the content of the slow log is empty, but we will try a select anyway
+--replace_column 1 TIMESTAMP 2 USER_HOST
+select * from slow_log;
+--replace_column 1 TIMESTAMP 2 USER_HOST
+select * from renamed_slow_log;
+
+# check that we can do whatever we want with disabled log
+set global general_log='OFF';
+RENAME TABLE general_log TO general_log2;
+
+set global slow_query_log='OFF';
+RENAME TABLE slow_log TO slow_log2;
+
+# this should fail
+--error ER_CANT_ACTIVATE_LOG
+set global general_log='ON';
+--error ER_CANT_ACTIVATE_LOG
+set global slow_query_log='ON';
+
+RENAME TABLE general_log2 TO general_log;
+RENAME TABLE slow_log2 TO slow_log;
+
+# this should work
+set global general_log='ON';
+set global slow_query_log='ON';
+# now check flush logs
+flush logs;
+flush logs;
+drop table renamed_general_log, renamed_slow_log;
+use test;
+
+#
+# Bug #21966 Strange warnings on repair of the log tables
+#
+
+use mysql;
+# check that no warning occurs on repair of the log tables
+repair table general_log;
+repair table slow_log;
+# check that no warning occurs on "create like" for the log tables
+create table general_log_new like general_log;
+create table slow_log_new like slow_log;
+show tables like "%log%";
+drop table slow_log_new, general_log_new;
+use test;
+
 # kill all connections
 disconnect con1;
 disconnect con2;

sql/handler.cc

@@ -1427,8 +1427,9 @@ bool handler::check_if_log_table_locking_is_allowed(uint sql_command,
 {
   /*
     Deny locking of the log tables, which is incompatible with
-    concurrent insert. Unless called from a logger THD:
-    general_log_thd or slow_log_thd.
+    concurrent insert. The routine is not called if the table is
+    being locked from a logger THD (general_log_thd or slow_log_thd)
+    or from a privileged thread (see log.cc for details)
   */
   if (table->s->log_table &&
       sql_command != SQLCOM_TRUNCATE &&

sql/handler.h

@@ -957,6 +957,10 @@ class handler :public Sql_alloc
         thd     Handler of the thread, trying to lock the table
         table   Table handler to check
         count   Number of locks already granted to the table
+        called_by_privileged_thread TRUE if called from a logger THD
+                                    (general_log_thd or slow_log_thd)
+                                    or by a privileged thread, which
+                                    has the right to lock log tables.
 
     DESCRIPTION
       Check whether a handler allows to lock the table. For instance,
@@ -972,7 +976,7 @@ class handler :public Sql_alloc
   virtual bool check_if_locking_is_allowed(uint sql_command,
                                            ulong type, TABLE *table,
                                            uint count,
-                                           bool called_by_logger_thread)
+                                           bool called_by_privileged_thread)
   {
     return TRUE;
   }

sql/lock.cc

@@ -691,7 +691,8 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
           check_if_locking_is_allowed(thd->lex->sql_command, thd->lex->type,
                                       table_ptr[i], count,
                                       (thd == logger.get_general_log_thd()) ||
-                                           (thd == logger.get_slow_log_thd())))
+                                      (thd == logger.get_slow_log_thd()) ||
+                                      (thd == logger.get_privileged_thread())))
       DBUG_RETURN(0);
   }
 

sql/log.h

@@ -403,6 +403,9 @@ class Log_event_handler
 };
 
 
+int check_if_log_table(uint db_len, const char *db, uint table_name_len,
+                       const char *table_name, uint check_if_opened);
+
 class Log_to_csv_event_handler: public Log_event_handler
 {
   /*
@@ -411,6 +414,16 @@ class Log_to_csv_event_handler: public Log_event_handler
     THD's of the query. The reason is the locking order and duration.
   */
   THD *general_log_thd, *slow_log_thd;
+  /*
+    This is for the thread, which called tmp_close_log_tables. The thread
+    will be allowed to write-lock the log tables (as it explicitly disabled
+    logging). This is used for such operations as REPAIR, which require
+    exclusive lock on the log tables.
+    NOTE: there can be only one priviliged thread, as one should
+    lock logger with logger.lock() before calling tmp_close_log_tables().
+    So no other thread could get privileged status at the same time.
+  */
+  THD *privileged_thread;
   friend class LOGGER;
   TABLE_LIST general_log, slow_log;
 
@@ -435,13 +448,20 @@ class Log_to_csv_event_handler: public Log_event_handler
                            const char *command_type, uint command_type_len,
                            const char *sql_text, uint sql_text_len,
                             CHARSET_INFO *client_cs);
-  bool flush(THD *thd, TABLE_LIST *close_slow_Log,
-             TABLE_LIST* close_general_log);
+  void tmp_close_log_tables(THD *thd);
   void close_log_table(uint log_type, bool lock_in_use);
   bool reopen_log_table(uint log_type);
+  THD* get_privileged_thread()
+  {
+    return privileged_thread;
+  }
 };
 
 
+/* type of the log table */
+#define QUERY_LOG_SLOW 1
+#define QUERY_LOG_GENERAL 2
+
 class Log_to_file_event_handler: public Log_event_handler
 {
   MYSQL_QUERY_LOG mysql_log;
@@ -497,13 +517,18 @@ class LOGGER
   {}
   void lock() { (void) pthread_mutex_lock(&LOCK_logger); }
   void unlock() { (void) pthread_mutex_unlock(&LOCK_logger); }
-  bool is_general_log_table_enabled()
+  void tmp_close_log_tables(THD *thd);
+  bool is_log_table_enabled(uint log_table_type)
   {
-    return table_log_handler && table_log_handler->general_log.table != 0;
-  }
-  bool is_slow_log_table_enabled()
-  {
-    return table_log_handler && table_log_handler->slow_log.table != 0;
+    switch (log_table_type) {
+    case QUERY_LOG_SLOW:
+      return table_log_handler && table_log_handler->slow_log.table != 0;
+    case QUERY_LOG_GENERAL:
+      return table_log_handler && table_log_handler->general_log.table != 0;
+    default:
+      DBUG_ASSERT(0);
+      return FALSE;                             /* make compiler happy */
+    }
   }
   /*
     We want to initialize all log mutexes as soon as possible,
@@ -541,6 +566,7 @@ class LOGGER
 
   void close_log_table(uint log_type, bool lock_in_use);
   bool reopen_log_table(uint log_type);
+  bool reopen_log_tables();
 
   /* we use this function to setup all enabled log event handlers */
   int set_handlers(uint error_log_printer,
@@ -563,6 +589,13 @@ class LOGGER
       return file_log_handler->get_mysql_log();
     return NULL;
   }
+  THD* get_privileged_thread()
+  {
+    if (table_log_handler)
+      return table_log_handler->get_privileged_thread();
+    else
+      return NULL;
+  }
 };
 
 enum enum_binlog_format {

sql/mysql_priv.h

@@ -1428,10 +1428,6 @@ void sql_print_information(const char *format, ...);
 typedef void (*sql_print_message_func)(const char *format, ...);
 extern sql_print_message_func sql_print_message_handlers[];
 
-/* type of the log table */
-#define QUERY_LOG_SLOW 1
-#define QUERY_LOG_GENERAL 2
-
 int error_log_print(enum loglevel level, const char *format,
                     va_list args);
 

sql/share/errmsg.txt

@@ -5960,3 +5960,5 @@ ER_HOSTNAME
 	eng "host name"
 ER_WRONG_STRING_LENGTH
 	eng "String '%-.70s' is too long for %s (should be no longer than %d)"
+ER_CANT_RENAME_LOG_TABLE
+        eng "Cannot rename '%s'. When logging enabled, rename to/from log table must rename two tables: the log table to an archive table and another table back to '%s'"

sql/sql_delete.cc

@@ -912,28 +912,16 @@ bool mysql_truncate(THD *thd, TABLE_LIST *table_list, bool dont_send_ok)
       DBUG_RETURN(TRUE);
   }
 
+  uint log_type= check_if_log_table(table_list->db_length, table_list->db,
+                                    table_list->table_name_length,
+                                    table_list->table_name, 1);
   /* close log tables in use */
-  if (!my_strcasecmp(system_charset_info, table_list->db, "mysql"))
+  if (log_type)
   {
-    if (opt_log &&
-        !my_strcasecmp(system_charset_info, table_list->table_name,
-                       "general_log"))
-    {
-      lock_logger= 1;
-      logger.lock();
-      logger.close_log_table(QUERY_LOG_GENERAL, FALSE);
-      closed_log_tables= closed_log_tables | QUERY_LOG_GENERAL;
-    }
-    else
-      if (opt_slow_log &&
-          !my_strcasecmp(system_charset_info, table_list->table_name,
-                         "slow_log"))
-      {
-        lock_logger= 1;
-        logger.lock();
-        logger.close_log_table(QUERY_LOG_SLOW, FALSE);
-        closed_log_tables= closed_log_tables | QUERY_LOG_SLOW;
-      }
+    lock_logger= 1;
+    logger.lock();
+    logger.close_log_table(log_type, FALSE);
+    closed_log_tables= closed_log_tables | log_type;
   }
 
   // Remove the .frm extension AIX 5.2 64-bit compiler bug (BUG#16155): this

sql/sql_rename.cc

@@ -35,7 +35,10 @@ static TABLE_LIST *reverse_table_list(TABLE_LIST *table_list);
 bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent)
 {
   bool error= 1;
-  TABLE_LIST *ren_table= 0;
+  TABLE_LIST *ren_table= 0, *new_table;
+  int to_table;
+  char *rename_log_table[2]= {NULL, NULL};
+  int disable_logs= 0;
   DBUG_ENTER("mysql_rename_tables");
 
   /*
@@ -52,6 +55,96 @@ bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent)
 
   if (wait_if_global_read_lock(thd,0,1))
     DBUG_RETURN(1);
+
+  if (logger.is_log_table_enabled(QUERY_LOG_GENERAL) ||
+      logger.is_log_table_enabled(QUERY_LOG_SLOW))
+  {
+
+    /*
+      Rules for rename of a log table:
+
+      IF   1. Log tables are enabled
+      AND  2. Rename operates on the log table and nothing is being
+              renamed to the log table.
+      DO   3. Throw an error message.
+      ELSE 4. Perform rename.
+    */
+
+    for (to_table= 0, ren_table= table_list; ren_table;
+         to_table= 1 - to_table, ren_table= ren_table->next_local)
+    {
+      int log_table_rename= 0;
+
+      if ((log_table_rename=
+           check_if_log_table(ren_table->db_length, ren_table->db,
+                              ren_table->table_name_length,
+                              ren_table->table_name, 1)))
+      {
+        /*
+          Log table encoutered we will need to disable and lock logs
+          for duration of rename.
+        */
+        disable_logs= TRUE;
+
+        /*
+          as we use log_table_rename as an array index, we need it to start
+          with 0, while QUERY_LOG_SLOW == 1 and QUERY_LOG_GENERAL == 2.
+          So, we shift the value to start with 0;
+        */
+        log_table_rename--;
+        if (rename_log_table[log_table_rename])
+        {
+          if (to_table)
+            rename_log_table[log_table_rename]= NULL;
+          else
+          {
+            /*
+              Two renames of "log_table TO" w/o rename "TO log_table" in
+              between.
+            */
+            my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), ren_table->table_name,
+                     ren_table->table_name);
+            DBUG_RETURN(1);
+          }
+        }
+        else
+        {
+          if (to_table)
+          {
+            /*
+              Attempt to rename a table TO log_table w/o renaming
+              log_table TO some table.
+            */
+            my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), ren_table->table_name,
+                     ren_table->table_name);
+            DBUG_RETURN(1);
+          }
+          else
+          {
+            /* save the name of the log table to report an error */
+            rename_log_table[log_table_rename]= ren_table->table_name;
+          }
+        }
+      }
+    }
+    if (rename_log_table[0] || rename_log_table[1])
+    {
+      if (rename_log_table[0])
+        my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), rename_log_table[0],
+                 rename_log_table[0]);
+      else
+        my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), rename_log_table[1],
+                 rename_log_table[1]);
+      DBUG_RETURN(1);
+    }
+
+    if (disable_logs)
+    {
+      logger.lock();
+      logger.tmp_close_log_tables(thd);
+    }
+  }
+
   VOID(pthread_mutex_lock(&LOCK_open));
   if (lock_table_names(thd, table_list))
     goto err;
@@ -95,6 +188,13 @@ bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent)
 
 err:
   pthread_mutex_unlock(&LOCK_open);
+  /* enable logging back if needed */
+  if (disable_logs)
+  {
+    if (logger.reopen_log_tables())
+      error= TRUE;
+    logger.unlock();
+  }
   start_waiting_global_read_lock(thd);
   DBUG_RETURN(error);
 }

sql/sql_table.cc

@@ -1622,11 +1622,8 @@ int mysql_rm_table_part2(THD *thd, TABLE_LIST *tables, bool if_exists,
 
     /* Disable drop of enabled log tables */
     if (share && share->log_table &&
-        ((!my_strcasecmp(system_charset_info, table->table_name,
-                         "general_log") && opt_log &&
-          logger.is_general_log_table_enabled()) ||
-         (!my_strcasecmp(system_charset_info, table->table_name, "slow_log")
-          && opt_slow_log && logger.is_slow_log_table_enabled())))
+        check_if_log_table(table->db_length, table->db,
+                           table->table_name_length, table->table_name, 1))
     {
       my_error(ER_CANT_DROP_LOG_TABLE, MYF(0));
       DBUG_RETURN(1);
@@ -4019,7 +4016,7 @@ static bool mysql_admin_table(THD* thd, TABLE_LIST* tables,
   Item *item;
   Protocol *protocol= thd->protocol;
   LEX *lex= thd->lex;
-  int result_code;
+  int result_code, disable_logs= 0;
   DBUG_ENTER("mysql_admin_table");
 
   if (end_active_trans(thd))
@@ -4064,6 +4061,23 @@ static bool mysql_admin_table(THD* thd, TABLE_LIST* tables,
     thd->no_warnings_for_error= no_warnings_for_error;
     if (view_operator_func == NULL)
       table->required_type=FRMTYPE_TABLE;
+
+    /*
+      If we want to perform an admin operation on the log table
+      (E.g. rename) and lock_type >= TL_READ_NO_INSERT disable
+      log tables
+    */
+
+    if (check_if_log_table(table->db_length, table->db,
+                                  table->table_name_length,
+                                  table->table_name, 1) &&
+        lock_type >= TL_READ_NO_INSERT)
+    {
+      disable_logs= 1;
+      logger.lock();
+      logger.tmp_close_log_tables(thd);
+    }
+
     open_and_lock_tables(thd, table);
     thd->no_warnings_for_error= 0;
     table->next_global= save_next_global;
@@ -4380,11 +4394,24 @@ static bool mysql_admin_table(THD* thd, TABLE_LIST* tables,
   }
 
   send_eof(thd);
+  if (disable_logs)
+  {
+    if (logger.reopen_log_tables())
+      my_error(ER_CANT_ACTIVATE_LOG, MYF(0));
+    logger.unlock();
+  }
   DBUG_RETURN(FALSE);
 
  err:
   ha_autocommit_or_rollback(thd, 1);
   close_thread_tables(thd);			// Shouldn't be needed
+  /* enable logging back if needed */
+  if (disable_logs)
+  {
+    if (logger.reopen_log_tables())
+      my_error(ER_CANT_ACTIVATE_LOG, MYF(0));
+    logger.unlock();
+  }
   if (table)
     table->table=0;
   DBUG_RETURN(TRUE);
@@ -4549,6 +4576,7 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
 {
   TABLE *tmp_table;
   char src_path[FN_REFLEN], dst_path[FN_REFLEN], tmp_path[FN_REFLEN];
+  char src_table_name_buff[FN_REFLEN], src_db_name_buff[FN_REFLEN];
   uint dst_path_length;
   char *db= table->db;
   char *table_name= table->table_name;
@@ -4585,13 +4613,6 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
     DBUG_RETURN(-1);
   }
 
-  bzero((gptr)&src_tables_list, sizeof(src_tables_list));
-  src_tables_list.db= src_db;
-  src_tables_list.table_name= src_table;
-
-  if (lock_and_wait_for_table_name(thd, &src_tables_list))
-    goto err;
-
   if ((tmp_table= find_temporary_table(thd, src_db, src_table)))
     strxmov(src_path, tmp_table->s->path.str, reg_ext, NullS);
   else
@@ -4618,6 +4639,34 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
     goto err;
   }
 
+  if (lower_case_table_names)
+  {
+    if (src_db)
+    {
+      strmake(src_db_name_buff, src_db,
+              min(sizeof(src_db_name_buff) - 1, table_ident->db.length));
+      my_casedn_str(files_charset_info, src_db_name_buff);
+      src_db= src_db_name_buff;
+    }
+    if (src_table)
+    {
+      strmake(src_table_name_buff, src_table,
+              min(sizeof(src_table_name_buff) - 1, table_ident->table.length));
+      my_casedn_str(files_charset_info, src_table_name_buff);
+      src_table= src_table_name_buff;
+    }
+  }
+
+  bzero((gptr)&src_tables_list, sizeof(src_tables_list));
+  src_tables_list.db= src_db;
+  src_tables_list.db_length= table_ident->db.length;
+  src_tables_list.lock_type= TL_READ;
+  src_tables_list.table_name= src_table;
+  src_tables_list.alias= src_table;
+
+  if (simple_open_n_lock_tables(thd, &src_tables_list))
+    DBUG_RETURN(TRUE);
+
   /*
     Validate the destination table
 
@@ -4764,9 +4813,6 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table,
     my_error(ER_TABLE_EXISTS_ERROR, MYF(0), table_name);
 
 err:
-  pthread_mutex_lock(&LOCK_open);
-  unlock_table_name(thd, &src_tables_list);
-  pthread_mutex_unlock(&LOCK_open);
   DBUG_RETURN(res);
 }
 
@@ -5153,37 +5199,27 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
   LINT_INIT(index_add_buffer);
   LINT_INIT(index_drop_buffer);
 
-  if (table_list && table_list->db &&
-      !my_strcasecmp(system_charset_info, table_list->db, "mysql") &&
-      table_list->table_name)
+  if (table_list && table_list->db && table_list->table_name)
   {
-    enum enum_table_kind { NOT_LOG_TABLE= 1, GENERAL_LOG, SLOW_LOG }
-         table_kind= NOT_LOG_TABLE;
+    int table_kind= 0;
 
-    if (!my_strcasecmp(system_charset_info, table_list->table_name,
-                       "general_log"))
-      table_kind= GENERAL_LOG;
-    else
-      if (!my_strcasecmp(system_charset_info, table_list->table_name,
-                         "slow_log"))
-        table_kind= SLOW_LOG;
+    table_kind= check_if_log_table(table_list->db_length, table_list->db,
+                                   table_list->table_name_length,
+                                   table_list->table_name, 0);
 
     /* Disable alter of enabled log tables */
-    if ((table_kind == GENERAL_LOG && opt_log &&
-        logger.is_general_log_table_enabled()) ||
-       (table_kind == SLOW_LOG && opt_slow_log &&
-         logger.is_slow_log_table_enabled()))
+    if (table_kind && logger.is_log_table_enabled(table_kind))
     {
       my_error(ER_CANT_ALTER_LOG_TABLE, MYF(0));
       DBUG_RETURN(TRUE);
     }
 
     /* Disable alter of log tables to unsupported engine */
-    if ((table_kind == GENERAL_LOG || table_kind == SLOW_LOG) &&
+    if (table_kind &&
         (lex_create_info->used_fields & HA_CREATE_USED_ENGINE) &&
         (!lex_create_info->db_type || /* unknown engine */
-        !(lex_create_info->db_type->db_type == DB_TYPE_MYISAM ||
-          lex_create_info->db_type->db_type == DB_TYPE_CSV_DB)))
+         !(lex_create_info->db_type->db_type == DB_TYPE_MYISAM ||
+           lex_create_info->db_type->db_type == DB_TYPE_CSV_DB)))
     {
       my_error(ER_BAD_LOG_ENGINE, MYF(0));
       DBUG_RETURN(TRUE);

sql/table.cc

@@ -363,25 +363,24 @@ int open_table_def(THD *thd, TABLE_SHARE *share, uint db_flags)
     error= open_binary_frm(thd, share, head, file);
     *root_ptr= old_root;
 
-    if (share->db.length == 5 &&
-        !my_strcasecmp(system_charset_info, share->db.str, "mysql"))
+    if (share->db.length == 5 && !(lower_case_table_names ?
+        my_strcasecmp(system_charset_info, share->db.str, "mysql") :
+        strcmp(share->db.str, "mysql")))
     {
       /*
         We can't mark all tables in 'mysql' database as system since we don't
         allow to lock such tables for writing with any other tables (even with
         other system tables) and some privilege tables need this.
       */
-      if (!my_strcasecmp(system_charset_info, share->table_name.str, "proc"))
+      if (!(lower_case_table_names ?
+            my_strcasecmp(system_charset_info, share->table_name.str, "proc") :
+            strcmp(share->table_name.str, "proc")))
         share->system_table= 1;
       else
       {
-        if (!my_strcasecmp(system_charset_info, share->table_name.str,
-                           "general_log"))
-          share->log_table= QUERY_LOG_GENERAL;
-        else
-          if (!my_strcasecmp(system_charset_info, share->table_name.str,
-                             "slow_log"))
-            share->log_table= QUERY_LOG_SLOW;
+        share->log_table= check_if_log_table(share->db.length, share->db.str,
+                                             share->table_name.length,
+                                             share->table_name.str, 0);
       }
     }
     error_given= 1;

storage/csv/ha_tina.cc

@@ -817,9 +817,9 @@ void ha_tina::update_status()
 bool ha_tina::check_if_locking_is_allowed(uint sql_command,
                                           ulong type, TABLE *table,
                                           uint count,
-                                          bool called_by_logger_thread)
+                                          bool called_by_privileged_thread)
 {
-  if (!called_by_logger_thread)
+  if (!called_by_privileged_thread)
     return check_if_log_table_locking_is_allowed(sql_command, type, table);
 
   return TRUE;

storage/myisam/ha_myisam.cc

@@ -255,7 +255,7 @@ int ha_myisam::dump(THD* thd, int fd)
 bool ha_myisam::check_if_locking_is_allowed(uint sql_command,
                                             ulong type, TABLE *table,
                                             uint count,
-                                            bool called_by_logger_thread)
+                                            bool called_by_privileged_thread)
 {
   /*
     To be able to open and lock for reading system tables like 'mysql.proc',
@@ -273,10 +273,10 @@ bool ha_myisam::check_if_locking_is_allowed(uint sql_command,
 
   /*
     Deny locking of the log tables, which is incompatible with
-    concurrent insert. Unless called from a logger THD:
-    general_log_thd or slow_log_thd.
+    concurrent insert. Unless called from a logger THD (general_log_thd
+    or slow_log_thd) or by a privileged thread.
   */
-  if (!called_by_logger_thread)
+  if (!called_by_privileged_thread)
     return check_if_log_table_locking_is_allowed(sql_command, type, table);
 
   return TRUE;