Fix for bug #13525 "Rename table does not keep info of triggers".

Let us transfer triggers associated with table when we rename it (but only if
we are not changing database to which table belongs, in the latter case we will
emit error).


mysql-test/r/trigger.result:
  Added test for bug #13525 "Rename table does not keep info of triggers".
mysql-test/t/trigger.test:
  Added test for bug #13525 "Rename table does not keep info of triggers".
sql/sql_rename.cc:
  rename_tables():
    Now after renaming table's .FRM file and updating handler data we call
    Table_triggers_list::change_table_name() which is reponsible for
    updating .TRG and .TRN files.
sql/sql_table.cc:
  mysql_alter_table():
    Now in case when ALTER should rename table we call
    Table_triggers_list::change_table_name() which is responsible
    for updating .TRG and .TRN files after renaming table.
sql/sql_trigger.cc:
  Added Table_triggers_list::change_table_name() method and
  change_table_name_in_triggers()/trignames() methods responsible for updating
  .TRG and .TRN files for table during its renaming.
  
  Two small cleanups - removed versioning for .TRG files (since it was not working
  before anyway) and emphasized that type of lock specified in tables list is
  unimportant for DROP TABLE (since this statement uses name-locking).
sql/sql_trigger.h:
  Table_triggers_list:
    Added on_table_names_list member to store pointers and lenghts of
    "ON table_name" parts in triggers' definitions to be able easily
    change them during RENAME TABLE.
    Added change_table_name() method and change_table_name_in_trignames/triggers()
    helper methods responsible for updating .TRG and .TRN files.
sql/sql_yacc.yy:
  trigger_tail:
    To be able properly update triggers' definitions with new table names
    when renaming tables we need to know where in CREATE TRIGGER statement
    "ON db_name.table_name" part resides.
    Small cleanup - let us emphasize that for CREATE TRIGGER statement 
    lock type which is specified in table list is unimportant since
    name-locking is used.

1 files changed, 269 insertions, 21 deletions

diff --git a/sql/sql_trigger.cc b/sql/sql_trigger.cc
index 8a26c2bafa2..90c62838759 100644
--- a/sql/sql_trigger.cc
+++ b/sql/sql_trigger.cc
@@ -58,7 +58,6 @@ static File_option triggers_file_parameters[]=
 */
 
 static const int TRG_NUM_REQUIRED_PARAMETERS= 4;
-static const int TRG_MAX_VERSIONS= 3;
 
 /*
   Structure representing contents of .TRN file which are used to support
@@ -455,8 +454,7 @@ bool Table_triggers_list::create_trigger(THD *thd, TABLE_LIST *tables,
                                definer_host->str, NullS) - trg_definer->str;
 
   if (!sql_create_definition_file(&dir, &file, &triggers_file_type,
-                                  (gptr)this, triggers_file_parameters,
-                                  TRG_MAX_VERSIONS))
+                                  (gptr)this, triggers_file_parameters, 0))
     return 0;
 
 err_with_cleanup:
@@ -480,7 +478,8 @@ err_with_cleanup:
     True  - error
 */
 
-static bool rm_trigger_file(char *path, char *db, char *table_name)
+static bool rm_trigger_file(char *path, const char *db,
+                            const char *table_name)
 {
   strxnmov(path, FN_REFLEN, mysql_data_home, "/", db, "/", table_name,
            triggers_file_ext, NullS);
@@ -504,7 +503,8 @@ static bool rm_trigger_file(char *path, char *db, char *table_name)
     True  - error
 */
 
-static bool rm_trigname_file(char *path, char *db, char *trigger_name)
+static bool rm_trigname_file(char *path, const char *db,
+                             const char *trigger_name)
 {
   strxnmov(path, FN_REFLEN, mysql_data_home, "/", db, "/", trigger_name,
            trigname_file_ext, NullS);
@@ -514,6 +514,38 @@ static bool rm_trigname_file(char *path, char *db, char *trigger_name)
 
 
 /*
+  Helper function that saves .TRG file for Table_triggers_list object.
+
+  SYNOPSIS
+    save_trigger_file()
+      triggers    Table_triggers_list object for which file should be saved
+      db          Name of database for subject table
+      table_name  Name of subject table
+
+  RETURN VALUE
+    FALSE  Success
+    TRUE   Error
+*/
+
+static bool save_trigger_file(Table_triggers_list *triggers, const char *db,
+                              const char *table_name)
+{
+  char dir_buff[FN_REFLEN], file_buff[FN_REFLEN];
+  LEX_STRING dir, file;
+
+  strxnmov(dir_buff, FN_REFLEN, mysql_data_home, "/", db, "/", NullS);
+  dir.length= unpack_filename(dir_buff, dir_buff);
+  dir.str= dir_buff;
+  file.length=  strxnmov(file_buff, FN_REFLEN, table_name, triggers_file_ext,
+                         NullS) - file_buff;
+  file.str= file_buff;
+
+  return sql_create_definition_file(&dir, &file, &triggers_file_type,
+                                    (gptr)triggers, triggers_file_parameters, 0);
+}
+
+
+/*
   Drop trigger for table.
 
   SYNOPSIS
@@ -566,20 +598,7 @@ bool Table_triggers_list::drop_trigger(THD *thd, TABLE_LIST *tables)
       }
       else
       {
-        char dir_buff[FN_REFLEN], file_buff[FN_REFLEN];
-        LEX_STRING dir, file;
-
-        strxnmov(dir_buff, FN_REFLEN, mysql_data_home, "/", tables->db,
-                 "/", NullS);
-        dir.length= unpack_filename(dir_buff, dir_buff);
-        dir.str= dir_buff;
-        file.length=  strxnmov(file_buff, FN_REFLEN, tables->table_name,
-                               triggers_file_ext, NullS) - file_buff;
-        file.str= file_buff;
-
-        if (sql_create_definition_file(&dir, &file, &triggers_file_type,
-                                       (gptr)this, triggers_file_parameters,
-                                       TRG_MAX_VERSIONS))
+        if (save_trigger_file(this, tables->db, tables->table_name))
           return 1;
       }
 
@@ -819,13 +838,13 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
       if (!names_only && triggers->prepare_record1_accessors(table))
         DBUG_RETURN(1);
 
-      char *trg_name_buff;
       List_iterator_fast<ulonglong> itm(triggers->definition_modes_list);
       List_iterator_fast<LEX_STRING> it_definer(triggers->
                                                 definers_list);
       LEX *old_lex= thd->lex, lex;
       sp_rcontext *save_spcont= thd->spcont;
       ulong save_sql_mode= thd->variables.sql_mode;
+      LEX_STRING *on_table_name;
 
       thd->lex= &lex;
 
@@ -890,6 +909,21 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
                                            &table->mem_root))
             goto err_with_lex_cleanup;
 
+        if (!(on_table_name= (LEX_STRING*) alloc_root(&table->mem_root,
+                                                      sizeof(LEX_STRING))))
+          goto err_with_lex_cleanup;
+        *on_table_name= lex.ident;
+        if (triggers->on_table_names_list.push_back(on_table_name, &table->mem_root))
+          goto err_with_lex_cleanup;
+
+        /*
+          Let us check that we correctly update trigger definitions when we
+          rename tables with triggers.
+        */
+        DBUG_ASSERT(!my_strcasecmp(table_alias_charset, lex.query_tables->db, db) &&
+                    !my_strcasecmp(table_alias_charset, lex.query_tables->table_name,
+                                   table_name));
+
         if (names_only)
         {
           lex_end(&lex);
@@ -1055,7 +1089,7 @@ static TABLE_LIST *add_table_for_trigger(THD *thd, sp_name *trig)
   lex->query_tables= 0;
   lex->query_tables_last= &lex->query_tables;
   DBUG_RETURN(sp_add_to_query_tables(thd, lex, trig->m_db.str,
-                                     trigname.trigger_table.str, TL_WRITE));
+                                     trigname.trigger_table.str, TL_IGNORE));
 }
 
 
@@ -1125,6 +1159,220 @@ end:
 }
 
 
+/*
+  Update .TRG file after renaming triggers' subject table
+  (change name of table in triggers' definitions).
+
+  SYNOPSIS
+    change_table_name_in_triggers()
+      thd                 Thread context
+      db_name             Database of subject table
+      old_table_name      Old subject table's name
+      new_table_name      New subject table's name
+
+  RETURN VALUE
+    FALSE  Success
+    TRUE   Failure
+*/
+
+bool
+Table_triggers_list::change_table_name_in_triggers(THD *thd,
+                                                   const char *db_name,
+                                                   LEX_STRING *old_table_name,
+                                                   LEX_STRING *new_table_name)
+{
+  char path_buff[FN_REFLEN];
+  LEX_STRING *def, *on_table_name, new_def;
+  ulonglong *sql_mode;
+  ulong save_sql_mode= thd->variables.sql_mode;
+  List_iterator_fast<LEX_STRING> it_def(definitions_list);
+  List_iterator_fast<LEX_STRING> it_on_table_name(on_table_names_list);
+  List_iterator_fast<ulonglong> it_mode(definition_modes_list);
+  uint on_q_table_name_len, before_on_len;
+  String buff;
+
+  DBUG_ASSERT(definitions_list.elements == on_table_names_list.elements &&
+              definitions_list.elements == definition_modes_list.elements);
+
+  while ((def= it_def++))
+  {
+    on_table_name= it_on_table_name++;
+    thd->variables.sql_mode= *(it_mode++);
+
+    /* Construct CREATE TRIGGER statement with new table name. */
+    buff.length(0);
+    before_on_len= on_table_name->str - def->str;
+    buff.append(def->str, before_on_len);
+    buff.append(STRING_WITH_LEN("ON "));
+    append_identifier(thd, &buff, new_table_name->str, new_table_name->length);
+    on_q_table_name_len= buff.length() - before_on_len;
+    buff.append(on_table_name->str + on_table_name->length,
+                def->length - (before_on_len + on_table_name->length));
+    /*
+      It is OK to allocate some memory on table's MEM_ROOT since this
+      table instance will be thrown out at the end of rename anyway.
+    */
+    new_def.str= memdup_root(&table->mem_root, buff.ptr(), buff.length());
+    new_def.length= buff.length();
+    on_table_name->str= new_def.str + before_on_len;
+    on_table_name->length= on_q_table_name_len;
+    *def= new_def;
+  }
+
+  thd->variables.sql_mode= save_sql_mode;
+
+  if (thd->is_fatal_error)
+    return TRUE; /* OOM */
+
+  if (save_trigger_file(this, db_name, new_table_name->str))
+    return TRUE;
+  if (rm_trigger_file(path_buff, db_name, old_table_name->str))
+  {
+    (void) rm_trigger_file(path_buff, db_name, new_table_name->str);
+    return TRUE;
+  }
+  return FALSE;
+}
+
+
+/*
+  Iterate though Table_triggers_list::names_list list and update .TRN files
+  after renaming triggers' subject table.
+
+  SYNOPSIS
+    change_table_name_in_trignames()
+      db_name             Database of subject table
+      new_table_name      New subject table's name
+      stopper             Pointer to Table_triggers_list::names_list at
+                          which we should stop updating.
+
+  RETURN VALUE
+    0      Success
+    non-0  Failure, pointer to Table_triggers_list::names_list element
+           for which update failed.
+*/
+
+LEX_STRING*
+Table_triggers_list::change_table_name_in_trignames(const char *db_name,
+                                                    LEX_STRING *new_table_name,
+                                                    LEX_STRING *stopper)
+{
+  char dir_buff[FN_REFLEN], trigname_buff[FN_REFLEN];
+  struct st_trigname trigname;
+  LEX_STRING dir, trigname_file;
+  LEX_STRING *trigger;
+  List_iterator_fast<LEX_STRING> it_name(names_list);
+
+  strxnmov(dir_buff, FN_REFLEN, mysql_data_home, "/", db_name, "/", NullS);
+  dir.length= unpack_filename(dir_buff, dir_buff);
+  dir.str= dir_buff;
+
+  while ((trigger= it_name++) != stopper)
+  {
+    trigname_file.length= strxnmov(trigname_buff, FN_REFLEN, trigger->str,
+                                   trigname_file_ext, NullS) - trigname_buff;
+    trigname_file.str= trigname_buff;
+
+    trigname.trigger_table= *new_table_name;
+
+    if (sql_create_definition_file(&dir, &trigname_file, &trigname_file_type,
+        (gptr)&trigname, trigname_file_parameters, 0))
+      return trigger;
+  }
+
+  return 0;
+}
+
+
+/*
+  Update .TRG and .TRN files after renaming triggers' subject table.
+
+  SYNOPSIS
+    change_table_name()
+      thd        Thread context
+      db         Old database of subject table
+      old_table  Old name of subject table
+      new_db     New database for subject table
+      new_table  New name of subject table
+
+  NOTE
+    This method tries to leave trigger related files in consistent state,
+    i.e. it either will complete successfully, or will fail leaving files
+    in their initial state.
+
+  RETURN VALUE
+    FALSE  Success
+    TRUE   Error
+*/
+
+bool Table_triggers_list::change_table_name(THD *thd, const char *db,
+                                            const char *old_table,
+                                            const char *new_db,
+                                            const char *new_table)
+{
+  TABLE table;
+  bool result= 0;
+  LEX_STRING *err_trigname;
+  DBUG_ENTER("change_table_name");
+
+  bzero(&table, sizeof(table));
+  init_alloc_root(&table.mem_root, 8192, 0);
+
+  safe_mutex_assert_owner(&LOCK_open);
+
+  if (Table_triggers_list::check_n_load(thd, db, old_table, &table, TRUE))
+  {
+    result= 1;
+    goto end;
+  }
+  if (table.triggers)
+  {
+    LEX_STRING_WITH_INIT old_table_name(old_table, strlen(old_table));
+    LEX_STRING_WITH_INIT new_table_name(new_table, strlen(new_table));
+    /*
+      Since triggers should be in the same schema as their subject tables
+      moving table with them between two schemas raises too many questions.
+      (E.g. what should happen if in new schema we already have trigger
+       with same name ?).
+    */
+    if (my_strcasecmp(table_alias_charset, db, new_db))
+    {
+      my_error(ER_TRG_IN_WRONG_SCHEMA, MYF(0));
+      result= 1;
+      goto end;
+    }
+    if (table.triggers->change_table_name_in_triggers(thd, db,
+                                                      &old_table_name,
+                                                      &new_table_name))
+    {
+      result= 1;
+      goto end;
+    }
+    if ((err_trigname= table.triggers->change_table_name_in_trignames(
+                                         db, &new_table_name, 0)))
+    {
+      /*
+        If we were unable to update one of .TRN files properly we will
+        revert all changes that we have done and report about error.
+        We assume that we will be able to undo our changes without errors
+        (we can't do much if there will be an error anyway).
+      */
+      (void) table.triggers->change_table_name_in_trignames(db,
+                                                            &old_table_name,
+                                                            err_trigname);
+      (void) table.triggers->change_table_name_in_triggers(thd, db,
+                                                           &new_table_name,
+                                                           &old_table_name);
+      result= 1;
+      goto end;
+    }
+  }
+end:
+  delete table.triggers;
+  free_root(&table.mem_root, MYF(0));
+  DBUG_RETURN(result);
+}
+
 
 bool Table_triggers_list::process_triggers(THD *thd, trg_event_type event,
                                            trg_action_time_type time_type,