- final fixes for bug#16431 (Events: An event which alters itself disappears)

- fix for bug#16423 (Events: SHOW CREATE EVENT doesn't work)
- this Changeset commits makes CREATE/UPDATE/DELETE EVENT real DDL statements
  by committing the currently open transaction before they are executed.
- this Changeset also fixes a trailing space problem since the very early days
  of the internal cron
- adds sophisticated checking of whether mysql.event was tampered accidentally
  or with purpose by an user.
- adds a lot of inline function documentation - documents everything left
  uncodumented
- INTERVAL_XXXX to XXX in I_S.EVENTS.INTERVAL_FIELD

WL#1034 (Internal CRON)


mysql-test/r/events.result:
  update result
mysql-test/t/events.test:
  add test cases for SHOW CREATE EVENT
  add test cases where the structure of mysql.event is changed and error reporting in this case
sql/event.cc:
  - do a lot more checking on mysql.event whether it's valid
    introduced generic function table_check_intact() which can be used also
    for checking whether a system table (mysql.*) has been tampered by user
    and report an error in this case. The checking is quite strict, thus
    maybe some mechanism can be added later that loosens this like some
    session variable, for instance, i_am_aware_that_i_can_damage_my_data
    so the table will be opened nevertheless we think that it's not valid.
  - add evex_show_create_event(THD *thd, sp_name *spn, LEX_STRING definer)
  - document a loooot. not a single function left undocumented.
sql/event.h:
  - add evex_show_create_event(THD *thd, sp_name *spn, LEX_STRING definer)
  - change get_show_create_event() to get_create_event()
  - add TABLE_FIELD_W_TYPE used by table_check_intact()
  - add event_timed::sql_mode so it can be used by show create event. currently
    always 0, will be fixed by a patch for another bug. At least makes the code
    of show create event complete.
sql/event_executor.cc:
  - add evex_check_system_tables() that checks on boot and event
    main thread startup that mysql.db and mysql.user tables are correct.
  - document everything!
sql/event_priv.h:
  remove a line
sql/event_timed.cc:
  - implement SHOW CREATE EVENT
  - document undocumented functions!
sql/share/errmsg.txt:
  - fix an error message and add two new
sql/sql_acl.cc:
  - add mysql.db table definition to use by table_check_intact()
  - exchange some of the positions by numbers from mysql.db to enum names (see sql_acl.h)
sql/sql_acl.h:
  - define the structure of mysql.db table
sql/sql_parse.cc:
  - handle SQLCOM_SHOW_CREATE_EVENT
  - end the current transaction becase CREATE/UPDATE/DELETE EVENT is a DDL
    statement
sql/sql_show.cc:
  - remove interval_type_to_name
  - use common function event_reconstruct_interval_expression()
    that reconstructs the expression given at create/alter, to some
    extent - interval of 2:62 MINUTE_SECOND will be reconstructed as
    interval of 3:02 MINUTE_SECOND!
sql/sql_yacc.yy:
  init the definer of event_timed also when doing SHOW CREATE EVENT
  because it's needed for checking into mysql.event
sql/table.cc:
  - remove stale code. only mysql.event should be a 'system_table'
  - add table_check_intact() to check the consistency of a table.
    mostly usable with mysql.xxx tables.
sql/table.h:
  - export TABLE_FIELD_W_TYPE and table_check_intact() which are used for 
    checking the structure of a table. mostly usable for mysql.xxx tables.

mysql-test/t/events.test

@@ -33,6 +33,138 @@ select count(*) from t_event3;
 drop event event3;
 drop table t_event3;
 
+
+set names utf8;
+#
+# SHOW CREATE EVENT test begin
+#
+CREATE EVENT root6 ON SCHEDULE EVERY '10:20' MINUTE_SECOND ON COMPLETION PRESERVE ENABLE COMMENT 'some comment' DO select 1;
+SHOW CREATE EVENT root6;
+create event root7 on schedule every 2 year do select 1;
+SHOW CREATE EVENT root7;
+create event root8 on schedule every '2:5' year_month do select 1;
+SHOW CREATE EVENT root8;
+create event root8_1 on schedule every '2:15' year_month do select 1;
+SHOW CREATE EVENT root8_1;
+create event root9 on schedule every 2 week ON COMPLETION PRESERVE DISABLE COMMENT 'коментар на кирилица' do select 1;
+SHOW CREATE EVENT root9;
+create event root10 on schedule every '20:5' day_hour do select 1;
+SHOW CREATE EVENT root10;
+create event root11 on schedule every '20:25' day_hour do select 1;
+SHOW CREATE EVENT root11;
+create event root12 on schedule every '20:25' hour_minute do select 1;
+SHOW CREATE EVENT root12;
+create event root13 on schedule every '25:25' hour_minute do select 1;
+SHOW CREATE EVENT root13;
+create event root13_1 on schedule every '11:65' hour_minute do select 1;
+SHOW CREATE EVENT root13_1;
+create event root14 on schedule every '35:35' minute_second do select 1;
+SHOW CREATE EVENT root14;
+create event root15 on schedule every '35:66' minute_second do select 1;
+SHOW CREATE EVENT root15;
+create event root16 on schedule every '35:56' day_minute do select 1;
+SHOW CREATE EVENT root16;
+create event root17 on schedule every '35:12:45' day_minute do select 1;
+SHOW CREATE EVENT root17;
+create event root17_1 on schedule every '35:25:65' day_minute do select 1;
+SHOW CREATE EVENT root17_1;
+create event root18 on schedule every '35:12:45' hour_second do select 1;
+SHOW CREATE EVENT root18;
+create event root19 on schedule every '15:59:85' hour_second do select 1;
+SHOW CREATE EVENT root19;
+create event root20 on schedule every '50:20:12:45' day_second do select 1;
+SHOW CREATE EVENT root20;
+set names cp1251;
+create event ðóóò21 on schedule every '50:23:59:95' day_second COMMENT 'òîâà å 1251 êîìåíòàð' do select 1;
+SHOW CREATE EVENT ðóóò21;
+insert into mysql.event (db, name, body, definer, interval_value, interval_field) values (database(), "root22", "select 1", user(), 100, "SECOND_MICROSECOND");
+--error 1535
+show create event root22;
+--error 1535
+SHOW EVENTS;
+drop event root22;
+drop event root6;
+drop event root7;
+drop event root8;
+drop event root8_1;
+drop event root9;
+drop event root10;
+drop event root11;
+drop event root12;
+drop event root13;
+drop event root13_1;
+drop event root14;
+drop event root15;
+drop event root16;
+drop event root17;
+drop event root17_1;
+drop event root18;
+drop event root19;
+drop event root20;
+drop event ðóóò21;
+
+set names latin1;
+#
+# SHOW CREATE EVENT test end
+#
+
+#
+# mysql.event intact checking start
+#
+# There should be at least 1 second between the ALTERs or we can't catch the change of create_time!!
+#
+CREATE EVENT intact_check ON SCHEDULE EVERY 10 HOUR DO SELECT "nothing";
+--replace_column 8 # 9 #
+SHOW EVENTS;
+ALTER TABLE mysql.event ADD dummy INT FIRST;
+--error 1525
+SHOW EVENTS;
+ALTER TABLE mysql.event DROP dummy, ADD dummy2 VARCHAR(64) FIRST;
+--error 1525
+SHOW EVENTS;
+ALTER TABLE mysql.event DROP dummy2;
+--replace_column 8 # 9 #
+SHOW EVENTS;
+CREATE TABLE event_like LIKE mysql.event;
+INSERT INTO event_like SELECT * FROM mysql.event;
+#sleep a bit or we won't catch the change of time
+--sleep 1
+ALTER TABLE mysql.event MODIFY db char(20) character set utf8 collate utf8_bin default '';
+#wait a bit or we won't see the difference because of seconds resolution
+--sleep 1
+SHOW CREATE TABLE mysql.event;
+--error 1526
+SELECT event_name FROM INFORMATION_SCHEMA.EVENTS;
+--sleep 1
+ALTER TABLE mysql.event MODIFY db char(64) character set utf8 collate utf8_bin default '';
+--sleep 1
+--echo "This should work"
+--replace_column 8 # 9 #
+SHOW EVENTS;
+--sleep 1
+ALTER TABLE mysql.event MODIFY db char(64) character set cp1251 default '';
+--error 1526
+SELECT event_name FROM INFORMATION_SCHEMA.EVENTS;
+--sleep 1
+ALTER TABLE mysql.event MODIFY db varchar(64) character set utf8 collate utf8_bin default '';
+--error 1526
+SELECT event_name FROM INFORMATION_SCHEMA.EVENTS;
+--sleep 1
+ALTER TABLE mysql.event DROP comment, DROP starts;
+--sleep 1
+--error 1525
+SELECT event_name FROM INFORMATION_SCHEMA.EVENTS;
+DROP TABLE mysql.event;
+CREATE TABLE mysql.event like event_like;
+INSERT INTO  mysql.event SELECT * FROM event_like;
+DROP TABLE event_like;
+--replace_column 8 # 9 #
+SHOW EVENTS;
+DROP EVENT intact_check;
+#
+# mysql.event intact checking end
+#
+
 #
 #INFORMATION_SCHEMA.EVENTS test begin
 #

sql/event.h

@@ -108,6 +108,7 @@ public:
   enum enum_event_on_completion on_completion;
   enum enum_event_status status;
   sp_head *sphead;
+  ulong sql_mode;
 
   const uchar *body_begin;
   
@@ -118,8 +119,9 @@ public:
   event_timed():running(0), status_changed(false), last_executed_changed(false),
                 expression(0), created(0), modified(0),
                 on_completion(MYSQL_EVENT_ON_COMPLETION_DROP),
-                status(MYSQL_EVENT_ENABLED), sphead(0), dropped(false),
-                free_sphead_on_delete(true), flags(0)
+                status(MYSQL_EVENT_ENABLED), sphead(0), sql_mode(0),
+                body_begin(0), dropped(false), free_sphead_on_delete(true),
+                flags(0)
                 
   {
     pthread_mutex_init(&this->LOCK_running, MY_MUTEX_INIT_FAST);
@@ -176,8 +178,8 @@ public:
   bool
   update_fields(THD *thd);
 
-  char *
-  get_show_create_event(THD *thd, uint32 *length);
+  int
+  get_create_event(THD *thd, String *buf);
   
   int
   execute(THD *thd, MEM_ROOT *mem_root= NULL);
@@ -220,8 +222,16 @@ evex_drop_event(THD *thd, event_timed *et, bool drop_if_exists,
 int
 evex_open_event_table(THD *thd, enum thr_lock_type lock_type, TABLE **table);
 
+int
+evex_show_create_event(THD *thd, sp_name *spn, LEX_STRING definer);
+
 int sortcmp_lex_string(LEX_STRING s, LEX_STRING t, CHARSET_INFO *cs);
 
+int
+event_reconstruct_interval_expression(String *buf,
+                                      interval_type interval,
+                                      longlong expression);
+
 int
 init_events();
 

sql/event_executor.cc

@@ -32,9 +32,9 @@
 extern  ulong thread_created;
 extern const char *my_localhost;
 
-pthread_mutex_t LOCK_event_arrays,
-                LOCK_workers_count,
-                LOCK_evex_running;
+pthread_mutex_t LOCK_event_arrays,  // mutex for when working with the queue
+                LOCK_workers_count, // mutex for when inc/dec uint workers_count
+                LOCK_evex_running;  // mutes for managing bool evex_is_running
 
 
 bool evex_is_running= false;
@@ -61,6 +61,19 @@ event_executor_worker(void *arg);
 pthread_handler_t
 event_executor_main(void *arg);
 
+
+/*
+   Returns the seconds difference of 2 TIME structs
+
+   SYNOPSIS
+     evex_time_diff()
+      a - TIME struct 1
+      b - TIME struct 2
+   
+   Returns:
+    the seconds difference
+*/
+
 static int
 evex_time_diff(TIME *a, TIME *b)
 {
@@ -68,6 +81,19 @@ evex_time_diff(TIME *a, TIME *b)
 }
 
 
+/*
+   Inits the mutexes used by the scheduler module
+
+   SYNOPSIS
+     evex_init_mutexes()
+          
+   NOTES
+    The mutexes are :
+      LOCK_event_arrays
+      LOCK_workers_count
+      LOCK_evex_running
+*/
+
 static void
 evex_init_mutexes()
 {
@@ -83,6 +109,75 @@ evex_init_mutexes()
 }
 
 
+/*
+  Opens mysql.db and mysql.user and checks whether
+  1. mysql.db has column Event_priv at column 20 (0 based);
+  2. mysql.user has column Event_priv at column 29 (0 based);
+  
+  Synopsis
+    evex_check_system_tables()
+*/
+
+void
+evex_check_system_tables()
+{
+  THD *thd= current_thd;
+  TABLE_LIST tables;
+  bool not_used;
+  Open_tables_state backup;
+
+  // thd is 0x0 during boot of the server. Later it's !=0x0
+  if (!thd)
+    return;
+
+  thd->reset_n_backup_open_tables_state(&backup);
+  
+  bzero((char*) &tables, sizeof(tables));
+  tables.db= (char*) "mysql";
+  tables.table_name= tables.alias= (char*) "db";
+  tables.lock_type= TL_READ;
+
+  if (simple_open_n_lock_tables(thd, &tables))
+    sql_print_error("Cannot open mysql.db");
+  else
+  {
+    table_check_intact(tables.table, MYSQL_DB_FIELD_COUNT, mysql_db_table_fields,
+                     &mysql_db_table_last_check,ER_EVENT_CANNOT_LOAD_FROM_TABLE);                           
+    close_thread_tables(thd);
+  }
+
+  bzero((char*) &tables, sizeof(tables));
+  tables.db= (char*) "mysql";
+  tables.table_name= tables.alias= (char*) "user";
+  tables.lock_type= TL_READ;
+
+  if (simple_open_n_lock_tables(thd, &tables))
+    sql_print_error("Cannot open mysql.db");
+  else
+  {
+    if (tables.table->s->fields < 29 ||
+      strncmp(tables.table->field[29]->field_name,
+                STRING_WITH_LEN("Event_priv")))
+      sql_print_error("mysql.user has no `Event_priv` column at position 29");
+
+    close_thread_tables(thd);
+  }
+
+  thd->restore_backup_open_tables_state(&backup);
+}
+
+
+/*
+   Inits the scheduler. Called on server start and every time the scheduler
+   is started with switching the event_scheduler global variable to TRUE 
+
+   SYNOPSIS
+     init_events()
+          
+   NOTES
+    Inits the mutexes used by the scheduler. Done at server start.
+*/
+
 int
 init_events()
 {
@@ -91,6 +186,8 @@ init_events()
   DBUG_ENTER("init_events");
 
   DBUG_PRINT("info",("Starting events main thread"));
+  
+  evex_check_system_tables();
 
   evex_init_mutexes();
 
@@ -113,6 +210,16 @@ init_events()
 }
 
 
+/*
+   Cleans up scheduler memory. Called on server shutdown.
+
+   SYNOPSIS
+     shutdown_events()
+          
+   NOTES
+    Destroys the mutexes.
+*/
+
 void
 shutdown_events()
 {
@@ -129,6 +236,22 @@ shutdown_events()
 }
 
 
+/*
+   Inits an scheduler thread handler, both the main and a worker
+
+   SYNOPSIS
+     init_event_thread()
+       thd - the THD of the thread. Has to be allocated by the caller.
+          
+   NOTES
+      1. The host of the thead is my_localhost
+      2. thd->net is initted with NULL - no communication.
+  
+  Returns
+     0  - OK
+    -1  - Error
+*/
+
 static int
 init_event_thread(THD* thd)
 {
@@ -165,6 +288,22 @@ init_event_thread(THD* thd)
   DBUG_RETURN(0);
 }
 
+
+/*
+   The main scheduler thread. Inits the priority queue on start and
+   destroys it on thread shutdown. Forks child threads for every event
+   execution. Sleeps between thread forking and does not do a busy wait.
+
+   SYNOPSIS
+     event_executor_main() 
+       arg - unused
+          
+   NOTES
+      1. The host of the thead is my_localhost
+      2. thd->net is initted with NULL - no communication.
+  
+*/
+
 pthread_handler_t
 event_executor_main(void *arg)
 {
@@ -436,6 +575,15 @@ err_no_thd:
 }
 
 
+/*
+   Function that executes an event in a child thread. Setups the 
+   environment for the event execution and cleans after that.
+
+   SYNOPSIS
+     event_executor_worker()
+       arg - the event_timed object to be processed
+*/
+
 pthread_handler_t
 event_executor_worker(void *event_void)
 {
@@ -561,6 +709,24 @@ err_no_thd:
 }
 
 
+/*
+   Loads all ENABLED events from mysql.event into the prioritized
+   queue. Called during scheduler main thread initialization. Compiles
+   the events. Creates event_timed instances for every ENABLED event
+   from mysql.event.
+
+   SYNOPSIS
+     evex_load_events_from_db()
+       thd - Thread context. Used for memory allocation in some cases.
+     
+   RETURNS
+     0  - OK
+    -1  - Error
+    
+   NOTES
+     Reports the error to the console
+*/
+
 static int
 evex_load_events_from_db(THD *thd)
 {
@@ -647,7 +813,22 @@ end:
 }
 
 
-bool sys_var_event_executor::update(THD *thd, set_var *var)
+/*
+   The update method of the global variable event_scheduler.
+   If event_scheduler is switched from 0 to 1 then the scheduler main
+   thread is started.
+
+   SYNOPSIS
+     event_executor_worker()
+       thd - Thread context (unused)
+       car - the new value
+   
+   Returns
+     0 - OK (always)
+*/
+
+bool
+sys_var_event_executor::update(THD *thd, set_var *var)
 {
   // here start the thread if not running.
   DBUG_ENTER("sys_var_event_executor::update");

sql/event_priv.h

@@ -40,7 +40,6 @@ evex_db_find_event_aux(THD *thd, const LEX_STRING dbname,
 int 
 event_timed_compare_q(void *vptr, byte* a, byte *b);
 
-
 #define EXEC_QUEUE_QUEUE_NAME executing_queue
 #define EXEC_QUEUE_DARR_NAME evex_executing_queue
 

sql/event_timed.cc

@@ -116,7 +116,10 @@ event_timed::init_body(THD *thd)
   while (body.length && body_begin[body.length-1] == '\0')
     body.length--;
 
-  body.str= strmake_root(root, (char *)body_begin, body.length);
+  //the first is always space which I cannot skip in the parser
+  DBUG_ASSERT(*body_begin == ' ');
+  body.length--;
+  body.str= strmake_root(root, (char *)body_begin + 1, body.length);
 
   DBUG_VOID_RETURN;
 }
@@ -847,6 +850,15 @@ err:
 }
 
 
+/*
+  Set the internal last_executed TIME struct to now. NOW is the
+  time according to thd->query_start(), so the THD's clock.
+  
+  Synopsis
+    event_timed::drop()
+      thd - thread context
+*/
+
 void
 event_timed::mark_last_executed(THD *thd)
 {
@@ -864,7 +876,13 @@ event_timed::mark_last_executed(THD *thd)
 
 
 /*
-  Returns :
+  Drops the event
+  
+  Synopsis
+    event_timed::drop()
+      thd - thread context
+
+  RETURNS :
     0 - OK
    -1 - Cannot open mysql.event
    -2 - Cannot find the event in mysql.event (already deleted?)
@@ -894,6 +912,22 @@ event_timed::drop(THD *thd)
 }
 
 
+/*
+  Saves status and last_executed_at to the disk if changed.
+  
+  Synopsis
+    event_timed::drop()
+      thd - thread context
+
+  Returns :
+    0 - OK
+    SP_OPEN_TABLE_FAILED - Error while opening mysql.event for writing
+    EVEX_WRITE_ROW_FAILED - On error to write to disk
+   
+   others - return code from SE in case deletion of the event row
+            failed.
+*/
+
 bool
 event_timed::update_fields(THD *thd)
 {
@@ -951,40 +985,75 @@ done:
 }
 
 
-char *
-event_timed::get_show_create_event(THD *thd, uint32 *length)
+/*
+  Get SHOW CREATE EVENT as string
+  
+  thd  - Thread
+  buf  - String*, should be already allocated. CREATE EVENT goes inside.
+  
+  Returns:
+  0 - OK
+  1 - Error (for now if mysql.event has been tampered and MICROSECONDS
+      interval or derivative has been put there.
+*/
+
+int
+event_timed::get_create_event(THD *thd, String *buf)
 {
-  char *dst, *ret;
-  uint len, tmp_len;
-  DBUG_ENTER("get_show_create_event");
+  int multipl= 0;
+  char tmp_buff[128];
+  String expr_buf(tmp_buff, sizeof(tmp_buff), system_charset_info);
+  expr_buf.length(0);
+
+  DBUG_ENTER("get_create_event");
   DBUG_PRINT("ret_info",("body_len=[%d]body=[%s]", body.length, body.str));
 
-  len = strlen("CREATE EVENT `") + dbname.length + strlen("`.`") + name.length +
-        strlen("` ON SCHEDULE EVERY 5 MINUTE DO ") + body.length;// + strlen(";");
-  
-  ret= dst= (char*) alloc_root(thd->mem_root, len + 1);
-  memcpy(dst, "CREATE EVENT `", tmp_len= strlen("CREATE EVENT `"));
-  dst+= tmp_len;
-  memcpy(dst, dbname.str, tmp_len=dbname.length);
-  dst+= tmp_len;
-  memcpy(dst, "`.`", tmp_len= strlen("`.`"));
-  dst+= tmp_len;
-  memcpy(dst, name.str, tmp_len= name.length);
-  dst+= tmp_len;
-  memcpy(dst, "` ON SCHEDULE EVERY 5 MINUTE DO ",
-         tmp_len= strlen("` ON SCHEDULE EVERY 5 MINUTE DO "));
-  dst+= tmp_len;
-
-  memcpy(dst, body.str, tmp_len= body.length);
-  dst+= tmp_len;
-//  memcpy(dst, ";", 1);
-//  ++dst;
-  *dst= '\0';
- 
-  *length= len;
-  
-  DBUG_PRINT("ret_info",("len=%d",*length));
-  DBUG_RETURN(ret);
+  if (expression &&
+      event_reconstruct_interval_expression(&expr_buf, interval, expression))
+      DBUG_RETURN(1);
+
+  buf->append(STRING_WITH_LEN("CREATE EVENT "));
+  append_identifier(thd, buf, dbname.str, dbname.length);
+  buf->append(STRING_WITH_LEN("."));
+  append_identifier(thd, buf, name.str, name.length);
+
+  buf->append(STRING_WITH_LEN(" ON SCHEDULE "));
+  if (expression)
+  {
+    buf->append(STRING_WITH_LEN("EVERY "));
+    buf->append(expr_buf);
+  }
+  else
+  {
+    char dtime_buff[20*2+32];// +32 to make my_snprintf_{8bit|ucs2} happy
+    buf->append(STRING_WITH_LEN("AT '"));
+    /* 
+      pass the buffer and the second param tells fills the buffer and returns
+      the number of chars to copy
+    */
+    buf->append(dtime_buff, my_datetime_to_str(&execute_at, dtime_buff));
+    buf->append(STRING_WITH_LEN("'"));
+  }
+
+  if (on_completion == MYSQL_EVENT_ON_COMPLETION_DROP)
+    buf->append(STRING_WITH_LEN(" ON COMPLETION NOT PRESERVE "));
+  else
+    buf->append(STRING_WITH_LEN(" ON COMPLETION PRESERVE "));
+
+  if (status == MYSQL_EVENT_ENABLED)
+    buf->append(STRING_WITH_LEN("ENABLE"));
+  else
+    buf->append(STRING_WITH_LEN("DISABLE"));
+
+  if (comment.length)
+  {
+    buf->append(STRING_WITH_LEN(" COMMENT "));
+    append_unescaped(buf, comment.str, comment.length);
+  }
+  buf->append(STRING_WITH_LEN(" DO "));
+  buf->append(body.str, body.length);  
+
+  DBUG_RETURN(0);
 }
 
 
@@ -1045,13 +1114,21 @@ done:
 
 
 /*
+  Compiles an event before it's execution. Compiles the anonymous
+  sp_head object held by the event
+  
+  Synopsis
+    event_timed::compile()
+      thd      - thread context, used for memory allocation mostly
+      mem_root - if != NULL then this memory root is used for allocs
+                 instead of thd->mem_root   
+  
   Returns
                      0 - Success
     EVEX_COMPILE_ERROR - Error during compilation
 
 */
 
-
 int
 event_timed::compile(THD *thd, MEM_ROOT *mem_root)
 {
@@ -1064,9 +1141,13 @@ event_timed::compile(THD *thd, MEM_ROOT *mem_root)
   char *old_query;
   uint old_query_len;
   st_sp_chistics *p;
-  CHARSET_INFO *old_character_set_client, *old_collation_connection,
+  char create_buf[2048];
+  String show_create(create_buf, sizeof(create_buf), system_charset_info);
+  CHARSET_INFO *old_character_set_client,
+               *old_collation_connection,
                *old_character_set_results;
-
+  
+  show_create.length(0);
   old_character_set_client= thd->variables.character_set_client;
   old_character_set_results= thd->variables.character_set_results;
   old_collation_connection= thd->variables.collation_connection;
@@ -1089,7 +1170,11 @@ event_timed::compile(THD *thd, MEM_ROOT *mem_root)
   old_query= thd->query;
   old_db= thd->db;
   thd->db= dbname.str;
-  thd->query= get_show_create_event(thd, &thd->query_length);
+
+  get_create_event(thd, &show_create);
+
+  thd->query= show_create.c_ptr();
+  thd->query_length= show_create.length();
   DBUG_PRINT("event_timed::compile", ("query:%s",thd->query));
 
   thd->lex= &lex;

sql/share/errmsg.txt

@@ -5779,10 +5779,10 @@ ER_EVENT_OPEN_TABLE_FAILED
         eng "Failed to open mysql.event"
 ER_EVENT_NEITHER_M_EXPR_NOR_M_AT
         eng "No datetime expression provided"
-ER_EVENT_COL_COUNT_DOESNT_MATCH
-        eng "Column count of %s.%s is wrong. Table probably corrupted"
+ER_COL_COUNT_DOESNT_MATCH_CORRUPTED
+        eng "Column count of mysql.%s is wrong. Table probably corrupted. Expected %d, found %d."
 ER_EVENT_CANNOT_LOAD_FROM_TABLE
-        eng "Cannot load from mysql.event. Table probably corrupted"
+        eng "Cannot load from mysql.%s. Table probably corrupted. See error log."
 ER_EVENT_CANNOT_DELETE
         eng "Failed to delete the event from mysql.event"
 ER_EVENT_COMPILE_ERROR
@@ -5798,3 +5798,5 @@ ER_CANT_WRITE_LOCK_LOG_TABLE
         eng "You can't write-lock a log table. Only read access is possible."
 ER_CANT_READ_LOCK_LOG_TABLE
         eng "You can't use usual read lock with log tables. Try READ LOCAL instead."
+ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE
+        eng "Column count of mysql.%s is wrong. Expected %d, found %d. Created with MySQL %d, now running %d. Please use scripts/mysql_fix_privilege_tables"

sql/sql_acl.cc

@@ -36,6 +36,122 @@
 
 #define FIRST_NON_YN_FIELD 26
 
+time_t mysql_db_table_last_check= 0L;
+
+TABLE_FIELD_W_TYPE mysql_db_table_fields[MYSQL_DB_FIELD_COUNT] = {
+  {
+    {(char *) STRING_WITH_LEN("Host")},            
+    {(char *) STRING_WITH_LEN("char(60)")},
+    {NULL, 0}
+  }, 
+  {
+    {(char *) STRING_WITH_LEN("Db")},            
+    {(char *) STRING_WITH_LEN("char(64)")},
+    {NULL, 0}
+  }, 
+  {
+    {(char *) STRING_WITH_LEN("User")},
+    {(char *) STRING_WITH_LEN("char(16)")},
+    {NULL, 0}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Select_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Insert_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Update_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Delete_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Create_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Drop_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Grant_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("References_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Index_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Alter_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Create_tmp_table_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Lock_tables_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Create_view_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Show_view_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Create_routine_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Alter_routine_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Execute_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Event_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  },
+  {
+    {(char *) STRING_WITH_LEN("Trigger_priv")},
+    {(char *) STRING_WITH_LEN("enum('N','Y')")},
+    {(char *) STRING_WITH_LEN("utf8")}
+  }
+};
+
+
 class acl_entry :public hash_filo_element
 {
 public:
@@ -435,14 +551,14 @@ static my_bool acl_load(THD *thd, TABLE_LIST *tables)
   while (!(read_record_info.read_record(&read_record_info)))
   {
     ACL_DB db;
-    update_hostname(&db.host,get_field(&mem, table->field[0]));
-    db.db=get_field(&mem, table->field[1]);
+    update_hostname(&db.host,get_field(&mem, table->field[MYSQL_DB_FIELD_HOST]));
+    db.db=get_field(&mem, table->field[MYSQL_DB_FIELD_DB]);
     if (!db.db)
     {
       sql_print_warning("Found an entry in the 'db' table with empty database name; Skipped");
       continue;
     }
-    db.user=get_field(&mem, table->field[2]);
+    db.user=get_field(&mem, table->field[MYSQL_DB_FIELD_USER]);
     if (check_no_resolve && hostname_requires_resolving(db.host.hostname))
     {
       sql_print_warning("'db' entry '%s %s@%s' "

sql/sql_acl.h

@@ -129,6 +129,36 @@
 				     (((A) & ALTER_PROC_ACL) >> 23) | \
 				     (((A) & GRANT_ACL) >> 8))
 
+enum mysql_db_table_field
+{
+  MYSQL_DB_FIELD_HOST = 0,
+  MYSQL_DB_FIELD_DB,
+  MYSQL_DB_FIELD_USER,
+  MYSQL_DB_FIELD_SELECT_PRIV,
+  MYSQL_DB_FIELD_INSERT_PRIV,
+  MYSQL_DB_FIELD_UPDATE_PRIV,
+  MYSQL_DB_FIELD_DELETE_PRIV,
+  MYSQL_DB_FIELD_CREATE_PRIV,
+  MYSQL_DB_FIELD_DROP_PRIV,
+  MYSQL_DB_FIELD_GRANT_PRIV,
+  MYSQL_DB_FIELD_REFERENCES_PRIV,
+  MYSQL_DB_FIELD_INDEX_PRIV,
+  MYSQL_DB_FIELD_ALTER_PRIV,
+  MYSQL_DB_FIELD_CREATE_TMP_TABLE_PRIV,
+  MYSQL_DB_FIELD_LOCK_TABLES_PRIV,
+  MYSQL_DB_FIELD_CREATE_VIEW_PRIV,
+  MYSQL_DB_FIELD_SHOW_VIEW_PRIV,
+  MYSQL_DB_FIELD_CREATE_ROUTINE_PRIV,
+  MYSQL_DB_FIELD_ALTER_ROUTINE_PRIV,
+  MYSQL_DB_FIELD_EXECUTE_PRIV,
+  MYSQL_DB_FIELD_EVENT_PRIV,
+  MYSQL_DB_FIELD_TRIGGER_PRIV,
+  MYSQL_DB_FIELD_COUNT
+};
+
+extern TABLE_FIELD_W_TYPE mysql_db_table_fields[];
+extern time_t mysql_db_table_last_check;
+
 /* Classes */
 
 struct acl_host_and_ip

sql/sql_parse.cc

@@ -3735,6 +3735,14 @@ end_with_restore_list:
   }
   case SQLCOM_SHOW_CREATE_EVENT:
   {
+    DBUG_ASSERT(lex->spname);
+    DBUG_ASSERT(lex->et);
+    if (! lex->spname->m_db.str)
+    {
+      my_message(ER_NO_DB_ERROR, ER(ER_NO_DB_ERROR), MYF(0));
+      res= true;
+      break;
+    }
     if (check_access(thd, EVENT_ACL, lex->spname->m_db.str, 0, 0, 0,
                      is_schema_db(lex->spname->m_db.str)))
       break;
@@ -3744,8 +3752,7 @@ end_with_restore_list:
       my_error(ER_TOO_LONG_IDENT, MYF(0), lex->spname->m_name.str);
       goto error;
     }
-    /* TODO : Implement it */
-    send_ok(thd, 1);
+    res= evex_show_create_event(thd, lex->spname, lex->et->definer);
     break;
   }
   case SQLCOM_CREATE_FUNCTION:                  // UDF function

sql/sql_show.cc

@@ -3772,30 +3772,6 @@ static int get_schema_partitions_record(THD *thd, struct st_table_list *tables,
 }
 
 
-static LEX_STRING interval_type_to_name[] = {
-  {(char *) STRING_WITH_LEN("INTERVAL_YEAR")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_QUARTER")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_MONTH")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_DAY")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_HOUR")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_MINUTE")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_WEEK")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_SECOND")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_MICROSECOND ")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_YEAR_MONTH")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_DAY_HOUR")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_DAY_MINUTE")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_DAY_SECOND")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_HOUR_MINUTE")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_HOUR_SECOND")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_MINUTE_SECOND")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_DAY_MICROSECOND")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_HOUR_MICROSECOND")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_MINUTE_MICROSECOND")}, 
-  {(char *) STRING_WITH_LEN("INTERVAL_SECOND_MICROSECOND")}
-}; 
-
-
 static interval_type get_real_interval_type(interval_type i_type)
 {
   switch (i_type) {
@@ -3869,6 +3845,7 @@ fill_events_copy_to_schema_table(THD *thd, TABLE *sch_table, TABLE *event_table)
   sch_table->field[9]->set_null();
   if (et.expression)
   {
+    String show_str;
     //type
     sch_table->field[5]->store(STRING_WITH_LEN("RECURRING"), scs);
     //execute_at
@@ -3877,9 +3854,11 @@ fill_events_copy_to_schema_table(THD *thd, TABLE *sch_table, TABLE *event_table)
     sch_table->field[7]->set_notnull();
     sch_table->field[7]->store((longlong) et.expression);
     //interval_type
-    LEX_STRING *ival=&interval_type_to_name[get_real_interval_type(et.interval)];
+    if (event_reconstruct_interval_expression(&show_str, et.interval,
+                                              et.expression))
+      DBUG_RETURN(1);
     sch_table->field[8]->set_notnull();
-    sch_table->field[8]->store(ival->str, ival->length, scs);
+    sch_table->field[8]->store(show_str.c_ptr(), show_str.length(), scs);
     //starts & ends
     sch_table->field[10]->set_notnull();
     sch_table->field[10]->store_time(&et.starts, MYSQL_TIMESTAMP_DATETIME);

sql/sql_yacc.yy

@@ -8402,6 +8402,10 @@ show_param:
           {
             Lex->sql_command = SQLCOM_SHOW_CREATE_EVENT;
             Lex->spname= $3;
+            Lex->et= new event_timed();
+            if (!Lex->et)
+              YYABORT;
+            Lex->et->init_definer(YYTHD);
           }
       ;
 

sql/table.cc

@@ -343,9 +343,7 @@ int open_table_def(THD *thd, TABLE_SHARE *share, uint db_flags)
         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")
-          || !my_strcasecmp(system_charset_info, share->table_name.str,
-                            "event"))
+      if (!my_strcasecmp(system_charset_info, share->table_name.str, "proc"))
         share->system_table= 1;
       else
       {
@@ -2296,6 +2294,144 @@ bool check_column_name(const char *name)
   return last_char_is_space || (uint) (name - start) > NAME_LEN;
 }
 
+
+/*
+  Checks whether a table is intact. Should be done *just* after the table has
+  been opened.
+  
+  Synopsis
+    table_check_intact()
+      table         - the table to check
+      table_f_count - expected number of columns in the table
+      table_def     - expected structure of the table (column name and type)
+    last_create_time- the table->file->create_time of the table in memory
+                      we have checked last time
+      error_num     - ER_XXXX from the error messages file. When 0 no error
+                      is sent to the client in case types does not match.
+                      If different col number either 
+                      ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE or 
+                      ER_COL_COUNT_DOESNT_MATCH_CORRUPTED is used
+
+  RETURNS
+    0   - OK
+    1   - There was an error
+*/
+
+my_bool
+table_check_intact(TABLE *table, uint table_f_count,
+                   TABLE_FIELD_W_TYPE *table_def, time_t *last_create_time,
+                   int error_num)
+{
+  uint i;
+  my_bool error= FALSE;
+  my_bool fields_diff_count;
+  DBUG_ENTER("table_check_intact");
+  DBUG_PRINT("info",("table=%s expected_count=%d",table->alias, table_f_count));
+  DBUG_PRINT("info",("last_create_time=%d", *last_create_time));
+  
+  if ((fields_diff_count= (table->s->fields != table_f_count)) ||
+      (*last_create_time != table->file->create_time))
+  {
+    DBUG_PRINT("info", ("I am suspecting, checking table"));
+    if (fields_diff_count)
+    {
+      // previous MySQL version
+      error= TRUE;
+      if (MYSQL_VERSION_ID > table->s->mysql_version)
+        my_error(ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE, MYF(0), table->alias,
+                 table_f_count, table->s->fields, table->s->mysql_version,
+                 MYSQL_VERSION_ID);
+      else if (MYSQL_VERSION_ID == table->s->mysql_version)
+        my_error(ER_COL_COUNT_DOESNT_MATCH_CORRUPTED,MYF(0), table->alias,
+                 table_f_count, table->s->fields);
+      else
+        /*
+          moving from newer mysql to older one -> let's say not an error but
+          will check the definition afterwards. If a column was added at the end
+          then we don't care much since it's not in the middle.
+        */
+        error= FALSE;
+    }
+    //definitely something has changed
+    char buffer[255];
+    for (i=0 ;i < table_f_count; ++i, ++table_def)
+    {      
+      Field *field= table->field[i];
+      String sql_type(buffer, sizeof(buffer), system_charset_info);
+      sql_type.length(0);
+      /*
+        name changes are not fatal, we use sequence numbers => no prob for us
+        but this can show tampered table or broken table.
+      */
+      if (!fields_diff_count || i < table->s->fields)
+      {
+        if (strncmp(field->field_name, table_def->name.str,
+                                       table_def->name.length))
+        {
+          sql_print_error("(%s) Expected field %s at position %d, found %s",
+                          table->alias, table_def->name.str, i,
+                          field->field_name);
+        }
+                        
+        /*
+          IF the type does not match than something is really wrong
+          Check up to length - 1. Why?
+          1. datetime -> datetim -> the same
+          2. int(11) -> int(11  -> the same
+          3. set('one','two') -> set('one','two'  
+             so for sets if the same prefix is there it's ok if more are
+             added as part of the set. The same is valid for enum. So a new
+             table running on a old server will be valid.
+        */ 
+        field->sql_type(sql_type);
+        if (strncmp(sql_type.c_ptr(), table_def->type.str,
+                    table_def->type.length - 1))
+        {
+          sql_print_error("(%s) Expected field %s at position %d to have type "
+                          "%s, found %s", table->alias, table_def->name.str,
+                          i, table_def->type.str, sql_type.c_ptr()); 
+          error= TRUE;
+        }
+        else if (table_def->cset.str && !field->has_charset())
+        {
+          sql_print_error("(%s) Expected field %s at position %d to have "
+                          "character set '%s' but found no such", table->alias,
+                          table_def->name.str, i, table_def->cset.str);        
+          error= TRUE;
+        }
+        else if (table_def->cset.str && 
+                 strcmp(field->charset()->csname, table_def->cset.str))
+        {
+          sql_print_error("(%s) Expected field %s at position %d to have "
+                          "character set '%s' but found '%s'", table->alias,
+                          table_def->name.str, i, table_def->cset.str,
+                          field->charset()->csname);
+          error= TRUE;
+        }
+      }
+      else
+      {
+        sql_print_error("(%s) Expected field %s at position %d to have type %s "
+                        " but no field found.", table_def->name.str,
+                        table_def->name.str, i, table_def->type.str);
+        error= TRUE;        
+      }
+    }
+    if (!error)
+      *last_create_time= table->file->create_time;
+    else if (!fields_diff_count && error_num)
+      my_error(error_num,MYF(0), table->alias, table_f_count, table->s->fields);
+  }
+  else
+  {
+    DBUG_PRINT("info", ("Table seems ok without through checking."));
+    *last_create_time= table->file->create_time;
+  }
+   
+  DBUG_RETURN(error);  
+}
+
+
 /*
   Create Item_field for each column in the table.
 

sql/table.h

@@ -864,4 +864,15 @@ typedef struct st_open_table_list{
   uint32 in_use,locked;
 } OPEN_TABLE_LIST;
 
+typedef struct st_table_field_w_type
+{
+  LEX_STRING name;
+  LEX_STRING type;
+  LEX_STRING cset;
+} TABLE_FIELD_W_TYPE;
+
 
+my_bool
+table_check_intact(TABLE *table, uint table_f_count,
+                   TABLE_FIELD_W_TYPE *table_def, time_t *last_create_time,
+                   int error_num);