This the 4-th patch in scope of CS patch (BUG#11986).

The patch contains the following changes:
  - Introduce auxilary functions to convenient work with character sets:
    - resolve_charset();
    - resolve_collation();
    - get_default_db_collation();
  - Introduce lex_string_set();
  - Refactor Table_trigger_list::process_triggers() &
    sp_head::execute_trigger() to be consistent with other code;
  - Move reusable code from add_table_for_trigger() into
    build_trn_path(), check_trn_exists() and load_table_name_for_trigger()
    to be used in the following patch.
  - Rename triggers_file_ext and trigname_file_ext into TRN_EXT and
    TRG_EXT respectively.

include/my_sys.h

@@ -904,6 +904,14 @@ extern CHARSET_INFO *get_charset(uint cs_number, myf flags);
 extern CHARSET_INFO *get_charset_by_name(const char *cs_name, myf flags);
 extern CHARSET_INFO *get_charset_by_csname(const char *cs_name,
 					   uint cs_flags, myf my_flags);
+
+extern bool resolve_charset(CHARSET_INFO **cs,
+                            const char *cs_name,
+                            CHARSET_INFO *default_cs);
+extern bool resolve_collation(CHARSET_INFO **cl,
+                              const char *cl_name,
+                              CHARSET_INFO *default_cl);
+
 extern void free_charsets(void);
 extern char *get_charsets_dir(char *buf);
 extern my_bool my_charset_same(CHARSET_INFO *cs1, CHARSET_INFO *cs2);

mysys/charset.c

@@ -573,6 +573,70 @@ CHARSET_INFO *get_charset_by_csname(const char *cs_name,
 }
 
 
+/**
+  Resolve character set by the character set name (utf8, latin1, ...).
+
+  The function tries to resolve character set by the specified name. If
+  there is character set with the given name, it is assigned to the "cs"
+  parameter and FALSE is returned. If there is no such character set,
+  "default_cs" is assigned to the "cs" and TRUE is returned.
+
+  @param[out] cs        Variable to store character set.
+  @param[in] cs_name    Character set name.
+  @param[in] default_cs Default character set.
+
+  @return FALSE if character set was resolved successfully; TRUE if there
+  is no character set with given name.
+*/
+
+bool resolve_charset(CHARSET_INFO **cs,
+                     const char *cs_name,
+                     CHARSET_INFO *default_cs)
+{
+  *cs= get_charset_by_csname(cs_name, MY_CS_PRIMARY, MYF(0));
+
+  if (*cs == NULL)
+  {
+    *cs= default_cs;
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
+
+/**
+  Resolve collation by the collation name (utf8_general_ci, ...).
+
+  The function tries to resolve collation by the specified name. If there
+  is collation with the given name, it is assigned to the "cl" parameter
+  and FALSE is returned. If there is no such collation, "default_cl" is
+  assigned to the "cl" and TRUE is returned.
+
+  @param[out] cl        Variable to store collation.
+  @param[in] cl_name    Collation name.
+  @param[in] default_cl Default collation.
+
+  @return FALSE if collation was resolved successfully; TRUE if there is no
+  collation with given name.
+*/
+
+bool resolve_collation(CHARSET_INFO **cl,
+                       const char *cl_name,
+                       CHARSET_INFO *default_cl)
+{
+  *cl= get_charset_by_name(cl_name, MYF(0));
+
+  if (*cl == NULL)
+  {
+    *cl= default_cl;
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
+
 /*
   Escape string with backslashes (\)
 

sql/handler.cc

@@ -3376,8 +3376,8 @@ TYPELIB *ha_known_exts(void)
     const char **ext, *old_ext;
 
     known_extensions_id= mysys_usage_id;
-    found_exts.push_back((char*) triggers_file_ext);
-    found_exts.push_back((char*) trigname_file_ext);
+    found_exts.push_back((char*) TRG_EXT);
+    found_exts.push_back((char*) TRN_EXT);
 
     plugin_foreach(NULL, exts_handlerton,
                    MYSQL_STORAGE_ENGINE_PLUGIN, &found_exts);

sql/mysql_priv.h

@@ -101,7 +101,7 @@ char* query_table_status(THD *thd,const char *db,const char *table_name);
                         ER_WARN_DEPRECATED_SYNTAX, ER(ER_WARN_DEPRECATED_SYNTAX),    \
                         (Old), (Ver), (New));                                        \
     else                                                                             \
-      sql_print_warning("The syntax %s is deprecated and will be removed "           \
+      sql_print_warning("The syntax '%s' is deprecated and will be removed "         \
                         "in MySQL %s. Please use %s instead.", (Old), (Ver), (New)); \
   } while(0)
 
@@ -1590,6 +1590,7 @@ bool check_db_dir_existence(const char *db_name);
 bool load_db_opt(THD *thd, const char *path, HA_CREATE_INFO *create);
 bool load_db_opt_by_name(THD *thd, const char *db_name,
                          HA_CREATE_INFO *db_create_info);
+CHARSET_INFO *get_default_db_collation(THD *thd, const char *db_name);
 bool my_dbopt_init(void);
 void my_dbopt_cleanup(void);
 extern int creating_database; // How many database locks are made
@@ -1610,8 +1611,8 @@ extern const char *first_keyword, *my_localhost, *delayed_user, *binary_keyword;
 extern const char **errmesg;			/* Error messages */
 extern const char *myisam_recover_options_str;
 extern const char *in_left_expr_name, *in_additional_cond, *in_having_cond;
-extern const char * const triggers_file_ext;
-extern const char * const trigname_file_ext;
+extern const char * const TRG_EXT;
+extern const char * const TRN_EXT;
 extern Eq_creator eq_creator;
 extern Ne_creator ne_creator;
 extern Gt_creator gt_creator;
@@ -2146,6 +2147,12 @@ bool schema_table_store_record(THD *thd, TABLE *table);
 int item_create_init();
 void item_create_cleanup();
 
+inline void lex_string_set(LEX_STRING *lex_str, const char *c_str)
+{
+  lex_str->str= (char *) c_str;
+  lex_str->length= strlen(c_str);
+}
+
 #endif /* MYSQL_SERVER */
 #endif /* MYSQL_CLIENT */
 

sql/sp_head.cc

@@ -1268,30 +1268,31 @@ set_routine_security_ctx(THD *thd, sp_head *sp, bool is_proc,
 #endif // ! NO_EMBEDDED_ACCESS_CHECKS
 
 
-/*
+/**
+  Execute trigger stored program.
+
   Execute a trigger:
-   - changes security context for triggers
-   - switch to new memroot
-   - call sp_head::execute
-   - restore old memroot
-   - restores security context
+   - changes security context for triggers;
+   - switch to new memroot;
+   - call sp_head::execute;
+   - restore old memroot;
+   - restores security context.
+
+  @param thd        Thread context.
+  @param db_name    Database name.
+  @param table_name Table name.
+  @param grant_info GRANT_INFO structure to be filled with information
+                    about definer's privileges on subject table.
 
-  SYNOPSIS
-    sp_head::execute_trigger()
-      thd               Thread handle
-      db                database name
-      table             table name
-      grant_info        GRANT_INFO structure to be filled with
-                        information about definer's privileges
-                        on subject table
-   
-  RETURN
-    FALSE  on success
-    TRUE   on error
+  @return Error status.
+    @retval FALSE on success.
+    @retval TRUE  on error.
 */
 
 bool
-sp_head::execute_trigger(THD *thd, const char *db, const char *table,
+sp_head::execute_trigger(THD *thd,
+                         const LEX_STRING *db_name,
+                         const LEX_STRING *table_name,
                          GRANT_INFO *grant_info)
 {
   sp_rcontext *octx = thd->spcont;
@@ -1304,6 +1305,46 @@ sp_head::execute_trigger(THD *thd, const char *db, const char *table,
   DBUG_ENTER("sp_head::execute_trigger");
   DBUG_PRINT("info", ("trigger %s", m_name.str));
 
+#ifndef NO_EMBEDDED_ACCESS_CHECKS
+  Security_context *save_ctx= NULL;
+
+
+  if (m_chistics->suid != SP_IS_NOT_SUID &&
+      m_security_ctx.change_security_context(thd,
+                                             &m_definer_user,
+                                             &m_definer_host,
+                                             &m_db,
+                                             &save_ctx))
+    DBUG_RETURN(TRUE);
+
+  /*
+    Fetch information about table-level privileges for subject table into
+    GRANT_INFO instance. The access check itself will happen in
+    Item_trigger_field, where this information will be used along with
+    information about column-level privileges.
+  */
+
+  fill_effective_table_privileges(thd,
+                                  grant_info,
+                                  db_name->str,
+                                  table_name->str);
+
+  /* Check that the definer has TRIGGER privilege on the subject table. */
+
+  if (!(grant_info->privilege & TRIGGER_ACL))
+  {
+    char priv_desc[128];
+    get_privilege_desc(priv_desc, sizeof(priv_desc), TRIGGER_ACL);
+
+    my_error(ER_TABLEACCESS_DENIED_ERROR, MYF(0), priv_desc,
+             thd->security_ctx->priv_user, thd->security_ctx->host_or_ip,
+             table_name->str);
+
+    m_security_ctx.restore_security_context(thd, save_ctx);
+    DBUG_RETURN(TRUE);
+  }
+#endif // NO_EMBEDDED_ACCESS_CHECKS
+
   /*
     Prepare arena and memroot for objects which lifetime is whole
     duration of trigger call (sp_rcontext, it's tables and items,
@@ -1336,6 +1377,11 @@ sp_head::execute_trigger(THD *thd, const char *db, const char *table,
 
 err_with_cleanup:
   thd->restore_active_arena(&call_arena, &backup_arena);
+
+#ifndef NO_EMBEDDED_ACCESS_CHECKS
+  m_security_ctx.restore_security_context(thd, save_ctx);
+#endif // NO_EMBEDDED_ACCESS_CHECKS
+
   delete nctx;
   call_arena.free_items();
   free_root(&call_mem_root, MYF(0));

sql/sp_head.h

@@ -216,8 +216,10 @@ public:
   destroy();
 
   bool
-  execute_trigger(THD *thd, const char *db, const char *table,
-                  GRANT_INFO *grant_onfo);
+  execute_trigger(THD *thd,
+                  const LEX_STRING *db_name,
+                  const LEX_STRING *table_name,
+                  GRANT_INFO *grant_info);
 
   bool
   execute_function(THD *thd, Item **args, uint argcount, Field *return_fld);

sql/sql_db.cc

@@ -538,6 +538,37 @@ bool load_db_opt_by_name(THD *thd, const char *db_name,
 }
 
 
+/**
+  Return default database collation.
+
+  @param thd     Thread context.
+  @param db_name Database name.
+
+  @return CHARSET_INFO object. The operation always return valid character
+    set, even if the database does not exist.
+*/
+
+CHARSET_INFO *get_default_db_collation(THD *thd, const char *db_name)
+{
+  HA_CREATE_INFO db_info;
+
+  if (thd->db != NULL && strcmp(db_name, thd->db) == 0)
+    return thd->db_charset;
+
+  load_db_opt_by_name(thd, db_name, &db_info);
+
+  /*
+    NOTE: even if load_db_opt_by_name() fails,
+    db_info.default_table_charset contains valid character set
+    (collation_server). We should not fail if load_db_opt_by_name() fails,
+    because it is valid case. If a database has been created just by
+    "mkdir", it does not contain db.opt file, but it is valid database.
+  */
+
+  return db_info.default_table_charset;
+}
+
+
 /*
   Create a database
 
@@ -751,10 +782,8 @@ bool mysql_alter_db(THD *thd, const char *db, HA_CREATE_INFO *create_info)
   if ((error=write_db_opt(thd, path, create_info)))
     goto exit;
 
-  /*
-     Change options if current database is being altered
-     TODO: Delete this code
-  */
+  /* Change options if current database is being altered. */
+
   if (thd->db && !strcmp(thd->db,db))
   {
     thd->db_charset= create_info->default_table_charset ?
@@ -1358,6 +1387,7 @@ bool mysql_change_db(THD *thd, const LEX_STRING *new_db_name, bool force_switch)
 
   Security_context *sctx= thd->security_ctx;
   ulong db_access= sctx->db_access;
+  CHARSET_INFO *db_default_cl;
 
   DBUG_ENTER("mysql_change_db");
   DBUG_PRINT("enter",("name: '%s'", new_db_name->str));
@@ -1487,16 +1517,9 @@ bool mysql_change_db(THD *thd, const LEX_STRING *new_db_name, bool force_switch)
     attributes and will be freed in THD::~THD().
   */
 
-  {
-    HA_CREATE_INFO db_options;
+  db_default_cl= get_default_db_collation(thd, new_db_file_name.str);
 
-    load_db_opt_by_name(thd, new_db_name->str, &db_options);
-
-    mysql_change_db_impl(thd, &new_db_file_name, db_access,
-                         db_options.default_table_charset ?
-                         db_options.default_table_charset :
-                         thd->variables.collation_server);
-  }
+  mysql_change_db_impl(thd, &new_db_file_name, db_access, db_default_cl);
 
   DBUG_RETURN(FALSE);
 }

sql/sql_trigger.h

@@ -17,7 +17,7 @@
 /*
   This class holds all information about triggers of table.
 
-  QQ: Will it be merged into TABLE in future ?
+  QQ: Will it be merged into TABLE in the future ?
 */
 
 class Table_triggers_list: public Sql_alloc
@@ -143,6 +143,17 @@ private:
 extern const LEX_STRING trg_action_time_type_names[];
 extern const LEX_STRING trg_event_type_names[];
 
-int
-add_table_for_trigger(THD *thd, sp_name *trig, bool if_exists,
-                      TABLE_LIST **table);
+bool add_table_for_trigger(THD *thd,
+                           sp_name *trg_name,
+                           bool continue_if_not_exist,
+                           TABLE_LIST **table);
+
+void build_trn_path(THD *thd, const sp_name *trg_name, LEX_STRING *trn_path);
+
+bool check_trn_exists(const LEX_STRING *trn_path);
+
+bool load_table_name_for_trigger(THD *thd,
+                                 const sp_name *trg_name,
+                                 const LEX_STRING *trn_path,
+                                 LEX_STRING *tbl_name);
+