Changed database, tablename and alias to be LEX_CSTRING

This was done in, among other things:
- thd->db and thd->db_length
- TABLE_LIST tablename, db, alias and schema_name
- Audit plugin database name
- lex->db
- All db and table names in Alter_table_ctx
- st_select_lex db

Other things:
- Changed a lot of functions to take const LEX_CSTRING* as argument
  for db, table_name and alias. See init_one_table() as an example.
- Changed some function arguments from LEX_CSTRING to const LEX_CSTRING
- Changed some lists from LEX_STRING to LEX_CSTRING
- threads_mysql.result changed because process list_db wasn't always
  correctly updated
- New append_identifier() function that takes LEX_CSTRING* as arguments
- Added new element tmp_buff to Alter_table_ctx to separate temp name
  handling from temporary space
- Ensure we store the length after my_casedn_str() of table/db names
- Removed not used version of rename_table_in_stat_tables()
- Changed Natural_join_column::table_name and db_name() to never return
  NULL (used for print)
- thd->get_db() now returns db as a printable string (thd->db.str or "")

7 files changed, 49 insertions, 50 deletions

diff --git a/plugin/audit_null/audit_null.c b/plugin/audit_null/audit_null.c
index 2747063670c..0f4efc25ef3 100644
--- a/plugin/audit_null/audit_null.c
+++ b/plugin/audit_null/audit_null.c
@@ -145,7 +145,7 @@ static void audit_null_notify(MYSQL_THD thd __attribute__((unused)),
       break;
     case MYSQL_AUDIT_TABLE_RENAME:
       snprintf(buf, sizeof(buf), "rename to %s.%s",
-               event_table->new_database, event_table->new_table);
+               event_table->new_database.str, event_table->new_table.str);
       buf[sizeof(buf)-1]= 0;
       op= buf;
       break;
@@ -154,7 +154,7 @@ static void audit_null_notify(MYSQL_THD thd __attribute__((unused)),
     fprintf(f, "%s[%s] @ %s [%s]\t%s.%s : %s\n",
             event_table->priv_user, event_table->user,
             event_table->host, ip,
-            event_table->database, event_table->table, op);
+            event_table->database.str, event_table->table.str, op);
   }
 }
 
diff --git a/plugin/feedback/feedback.cc b/plugin/feedback/feedback.cc
index 8ed6ef64b0c..826a929643d 100644
--- a/plugin/feedback/feedback.cc
+++ b/plugin/feedback/feedback.cc
@@ -93,7 +93,7 @@ static COND* make_cond(THD *thd, TABLE_LIST *tables, LEX_STRING *filter)
 {
   Item_cond_or *res= NULL;
   Name_resolution_context nrc;
-  const char *db= tables->db, *table= tables->alias;
+  const char *db= tables->db.str, *table= tables->alias.str;
   LEX_CSTRING *field= &tables->table->field[0]->field_name;
   CHARSET_INFO *cs= &my_charset_latin1;
 
diff --git a/plugin/feedback/sender_thread.cc b/plugin/feedback/sender_thread.cc
index bcd10f6713f..0463a70a383 100644
--- a/plugin/feedback/sender_thread.cc
+++ b/plugin/feedback/sender_thread.cc
@@ -105,8 +105,7 @@ static int prepare_for_fill(TABLE_LIST *tables)
   thd->set_time();
   thd->init_for_queries();
   thd->real_id= pthread_self();
-  thd->db= NULL;
-  thd->db_length= 0;
+  thd->db= null_clex_str;
   thd->security_ctx->host_or_ip= "";
   thd->security_ctx->db_access= DB_ACLS;
   thd->security_ctx->master_access= ~NO_ACCESS;
@@ -114,11 +113,9 @@ static int prepare_for_fill(TABLE_LIST *tables)
   lex_start(thd);
   mysql_init_select(thd->lex);
 
-  tables->init_one_table(INFORMATION_SCHEMA_NAME.str,
-                         INFORMATION_SCHEMA_NAME.length,
-                         i_s_feedback->table_name,
-                         strlen(i_s_feedback->table_name),
-                         0, TL_READ);
+  LEX_CSTRING tbl_name= {i_s_feedback->table_name, strlen(i_s_feedback->table_name) };
+
+  tables->init_one_table(&INFORMATION_SCHEMA_NAME, &tbl_name, 0, TL_READ);
   tables->schema_table= i_s_feedback;
   tables->table= create_schema_table(thd, tables);
   if (!tables->table)
diff --git a/plugin/handler_socket/handlersocket/database.cpp b/plugin/handler_socket/handlersocket/database.cpp
index b21d58d243b..a76428b29d3 100644
--- a/plugin/handler_socket/handlersocket/database.cpp
+++ b/plugin/handler_socket/handlersocket/database.cpp
@@ -297,9 +297,9 @@ dbcontext::init_thread(const void *stack_bottom, volatile int& shutdown_flag)
       #else
       thd->options |= OPTION_BIN_LOG;
       #endif
-      safeFree(thd->db);
-      thd->db = 0;
-      thd->db = my_strdup("handlersocket", MYF(0));
+      safeFree((char*) thd->db.str);
+      thd->db.str= my_strdup("handlersocket", MYF(0));
+      thd->db.length= sizeof("handlersocket")-1;
     }
     thd->variables.option_bits |= OPTION_TABLE_LOCK;
     my_pthread_setspecific_ptr(THR_THD, thd);
@@ -1005,8 +1005,9 @@ dbcontext::cmd_open(dbcallback_i& cb, const cmd_open_args& arg)
     bool refresh = true;
     const thr_lock_type lock_type = for_write_flag ? TL_WRITE : TL_READ;
     #if MYSQL_VERSION_ID >= 50505
-    tables.init_one_table(arg.dbn, strlen(arg.dbn), arg.tbl, strlen(arg.tbl),
-      arg.tbl, lock_type);
+    LEX_CSTRING db_name=  { arg.dbn, strlen(arg.dbn) };
+    LEX_CSTRING tbl_name= { arg.tbl, strlen(arg.tbl) };
+    tables.init_one_table(&db_name, &tbl_name, 0, lock_type);
     tables.mdl_request.init(MDL_key::TABLE, arg.dbn, arg.tbl,
       for_write_flag ? MDL_SHARED_WRITE : MDL_SHARED_READ, MDL_TRANSACTION);
     Open_table_context ot_act(thd, 0);
diff --git a/plugin/server_audit/server_audit.c b/plugin/server_audit/server_audit.c
index 6b0443344e9..38046de61f9 100644
--- a/plugin/server_audit/server_audit.c
+++ b/plugin/server_audit/server_audit.c
@@ -1088,7 +1088,7 @@ static void setup_connection_connect(struct connection_info *cn,
   cn->log_always= 0;
   cn->thread_id= event->thread_id;
   get_str_n(cn->db, &cn->db_length, sizeof(cn->db),
-            event->database, event->database_length);
+            event->database.str, event->database.length);
   get_str_n(cn->user, &cn->user_length, sizeof(cn->db),
             event->user, event->user_length);
   get_str_n(cn->host, &cn->host_length, sizeof(cn->host),
@@ -1176,7 +1176,7 @@ static void setup_connection_table(struct connection_info *cn,
   cn->log_always= 0;
   cn->query_length= 0;
   get_str_n(cn->db, &cn->db_length, sizeof(cn->db),
-            event->database, event->database_length);
+            event->database.str, event->database.length);
   get_str_n(cn->user, &cn->user_length, sizeof(cn->db),
             event->user, SAFE_STRLEN(event->user));
   get_str_n(cn->host, &cn->host_length, sizeof(cn->host),
@@ -1324,7 +1324,7 @@ static int log_connection_event(const struct mysql_event_connection *event,
                     event->ip, event->ip_length,
                     event->thread_id, 0, type);
   csize+= my_snprintf(message+csize, sizeof(message) - 1 - csize,
-    ",%.*s,,%d", event->database_length, event->database, event->status);
+    ",%.*s,,%d", event->database.length, event->database.str, event->status);
   message[csize]= '\n';
   return write_log(message, csize + 1);
 }
@@ -1742,8 +1742,8 @@ static int log_table(const struct connection_info *cn,
                     event->ip, (unsigned int)SAFE_STRLEN(event->ip),
                     event->thread_id, cn->query_id, type);
   csize+= my_snprintf(message+csize, sizeof(message) - 1 - csize,
-            ",%.*s,%.*s,",event->database_length, event->database,
-                          event->table_length, event->table);
+            ",%.*s,%.*s,",event->database.length, event->database.str,
+                          event->table.length, event->table.str);
   message[csize]= '\n';
   return write_log(message, csize + 1);
 }
@@ -1764,10 +1764,10 @@ static int log_rename(const struct connection_info *cn,
                     event->ip, (unsigned int)SAFE_STRLEN(event->ip),
                     event->thread_id, cn->query_id, "RENAME");
   csize+= my_snprintf(message+csize, sizeof(message) - 1 - csize,
-            ",%.*s,%.*s|%.*s.%.*s,",event->database_length, event->database,
-                         event->table_length, event->table,
-                         event->new_database_length, event->new_database,
-                         event->new_table_length, event->new_table);
+            ",%.*s,%.*s|%.*s.%.*s,",event->database.length, event->database.str,
+                         event->table.length, event->table.str,
+                         event->new_database.length, event->new_database.str,
+                         event->new_table.length, event->new_table.str);
   message[csize]= '\n';
   return write_log(message, csize + 1);
 }
@@ -1832,7 +1832,7 @@ static void update_connection_info(struct connection_info *cn,
             /* Change DB */
             if (mysql_57_started)
               get_str_n(cn->db, &cn->db_length, sizeof(cn->db),
-                  event->database, event->database_length);
+                  event->database.str, event->database.length);
             else
               get_str_n(cn->db, &cn->db_length, sizeof(cn->db),
                   event->general_query, event->general_query_length);
@@ -1858,9 +1858,9 @@ static void update_connection_info(struct connection_info *cn,
           if (ci_needs_setup(cn))
             setup_connection_query(cn, event);
 
-          if (mode == 0 && cn->db_length == 0 && event->database_length > 0)
+          if (mode == 0 && cn->db_length == 0 && event->database.length > 0)
             get_str_n(cn->db, &cn->db_length, sizeof(cn->db),
-                      event->database, event->database_length);
+                      event->database.str, event->database.length);
 
           if (event->general_error_code == 0)
           {
@@ -1875,7 +1875,7 @@ static void update_connection_info(struct connection_info *cn,
                     event->general_query + 4, event->general_query_length - 4);
               else
                 get_str_n(cn->db, &cn->db_length, sizeof(cn->db),
-                    event->database, event->database_length);
+                    event->database.str, event->database.length);
             }
           }
           update_general_user(cn, event);
@@ -1916,9 +1916,9 @@ static void update_connection_info(struct connection_info *cn,
                 event->ip, SAFE_STRLEN(event->ip));
     }
 
-    if (cn->db_length == 0 && event->database_length != 0)
+    if (cn->db_length == 0 && event->database.length != 0)
       get_str_n(cn->db, &cn->db_length, sizeof(cn->db),
-                event->database, event->database_length);
+                event->database.str, event->database.length);
 
     if (mode == 0)
       cn->query_id= event->query_id;
@@ -2145,8 +2145,8 @@ static void auditing_v8(MYSQL_THD thd, struct mysql_event_general_v8 *ev_v8)
   event.general_charset= ev_v8->general_charset;
   event.general_time= ev_v8->general_time;
   event.general_rows= ev_v8->general_rows;
-  event.database= 0;
-  event.database_length= 0;
+  event.database.str= 0;
+  event.database.length= 0;
 
   if (event.general_query_length > 0)
   {
@@ -2154,8 +2154,8 @@ static void auditing_v8(MYSQL_THD thd, struct mysql_event_general_v8 *ev_v8)
     event.general_command= "Query";
     event.general_command_length= 5;
 #ifdef __linux__
-    event.database= *(char **) (((char *) thd) + db_off);
-    event.database_length= *(size_t *) (((char *) thd) + db_len_off);
+    event.database.str= *(char **) (((char *) thd) + db_off);
+    event.database.length= *(size_t *) (((char *) thd) + db_len_off);
 #endif /*__linux*/
   }
 #ifdef __linux__
diff --git a/plugin/userstat/index_stats.cc b/plugin/userstat/index_stats.cc
index 87e6da63e38..0528507c50e 100644
--- a/plugin/userstat/index_stats.cc
+++ b/plugin/userstat/index_stats.cc
@@ -17,27 +17,26 @@ static int index_stats_fill(THD *thd, TABLE_LIST *tables, COND *cond)
     INDEX_STATS *index_stats =
       (INDEX_STATS*) my_hash_element(&global_index_stats, i);
     TABLE_LIST tmp_table;
-    char *index_name;
-    size_t schema_name_length, table_name_length, index_name_length;
+    const char *index_name;
+    size_t index_name_length;
 
     bzero((char*) &tmp_table,sizeof(tmp_table));
-    tmp_table.db=         index_stats->index;
-    tmp_table.table_name= strend(index_stats->index)+1;
+    tmp_table.db.str=    index_stats->index;
+    tmp_table.db.length= strlen(index_stats->index);
+    tmp_table.table_name.str= index_stats->index + tmp_table.db.length + 1;
+    tmp_table.table_name.length= strlen(tmp_table.table_name.str);
     tmp_table.grant.privilege= 0;
-    if (check_access(thd, SELECT_ACL, tmp_table.db,
+    if (check_access(thd, SELECT_ACL, tmp_table.db.str,
                       &tmp_table.grant.privilege, NULL, 0, 1) ||
         check_grant(thd, SELECT_ACL, &tmp_table, 1, UINT_MAX, 1))
       continue;
 
-    index_name=         strend(tmp_table.table_name)+1;
-    schema_name_length= (tmp_table.table_name - index_stats->index) -1;
-    table_name_length=  (index_name - tmp_table.table_name)-1;
-    index_name_length=  (index_stats->index_name_length - schema_name_length -
-                         table_name_length - 3);
+    index_name=         tmp_table.table_name.str + tmp_table.table_name.length + 1;
+    index_name_length=  (index_stats->index_name_length - tmp_table.db.length -
+                         tmp_table.table_name.length - 3);
 
-    table->field[0]->store(tmp_table.db, (uint)schema_name_length,
-                           system_charset_info);
-    table->field[1]->store(tmp_table.table_name, (uint) table_name_length,
+    table->field[0]->store(tmp_table.db.str, tmp_table.db.length, system_charset_info);
+    table->field[1]->store(tmp_table.table_name.str, tmp_table.table_name.length,
                            system_charset_info);
     table->field[2]->store(index_name, (uint) index_name_length, system_charset_info);
     table->field[3]->store((longlong)index_stats->rows_read, TRUE);
diff --git a/plugin/userstat/table_stats.cc b/plugin/userstat/table_stats.cc
index 7b522a388d7..3119e516e06 100644
--- a/plugin/userstat/table_stats.cc
+++ b/plugin/userstat/table_stats.cc
@@ -26,10 +26,12 @@ static int table_stats_fill(THD *thd, TABLE_LIST *tables, COND *cond)
     table_name_length= strlen(table_stats->table + schema_length + 1);
 
     bzero((char*) &tmp_table,sizeof(tmp_table));
-    tmp_table.db=         table_stats->table;
-    tmp_table.table_name= end_of_schema+1;
+    tmp_table.db.str= table_stats->table;
+    tmp_table.db.length= schema_length;
+    tmp_table.table_name.str= end_of_schema+1;
+    tmp_table.table_name.length= table_name_length;
     tmp_table.grant.privilege= 0;
-    if (check_access(thd, SELECT_ACL, tmp_table.db,
+    if (check_access(thd, SELECT_ACL, tmp_table.db.str,
                      &tmp_table.grant.privilege, NULL, 0, 1) ||
         check_grant(thd, SELECT_ACL, &tmp_table, 1, UINT_MAX,
                     1))