Additional fix for BUG#16777: Can not create trigger nor view

w/o definer if --skip-grant-tables specified.
  
The previous patch does not allow to specify empty host name in
DEFINER-clause explicitly.

mysql-test/r/skip_grants.result

-drop table if exists t1,v1;
-drop view if exists t1,v1;
-drop procedure if exists f1;
 use test;
-create procedure f1() select 1;
-drop procedure f1;
-create table t1 (a int);
-create definer='user'@'host' sql security definer view v1 as select * from t1;
-drop view v1;
-drop table t1;
-drop function if exists f1;
-Warnings:
-Note	1305	FUNCTION f1 does not exist
 DROP VIEW IF EXISTS v1;
 DROP VIEW IF EXISTS v2;
+DROP VIEW IF EXISTS v3;
 DROP TABLE IF EXISTS t1;
+DROP PROCEDURE IF EXISTS p1;
+DROP PROCEDURE IF EXISTS p2;
+DROP PROCEDURE IF EXISTS p3;
+DROP FUNCTION IF EXISTS f1;
+DROP FUNCTION IF EXISTS f2;
+DROP FUNCTION IF EXISTS f3;
 CREATE TABLE t1(c INT);
 CREATE TRIGGER t1_bi BEFORE INSERT ON t1
 FOR EACH ROW
 SET @a = 1;
 CREATE VIEW v1 AS SELECT * FROM t1;
+CREATE PROCEDURE p1()
+SELECT 1;
+CREATE FUNCTION f1() RETURNS INT
+RETURN 1;
 CREATE DEFINER=a@b TRIGGER ti_ai AFTER INSERT ON t1
 FOR EACH ROW
 SET @b = 1;
 CREATE DEFINER=a@b VIEW v2 AS SELECT * FROM t1;
+CREATE DEFINER=a@b PROCEDURE p2()
+SELECT 2;
+CREATE DEFINER=a@b FUNCTION f2() RETURNS INT
+RETURN 2;
+CREATE DEFINER=a@'' TRIGGER ti_bu BEFORE UPDATE ON t1
+FOR EACH ROW
+SET @c = 1;
+CREATE DEFINER=a@'' VIEW v3 AS SELECT * FROM t1;
+CREATE DEFINER=a@'' PROCEDURE p3()
+SELECT 3;
+CREATE DEFINER=a@'' FUNCTION f3() RETURNS INT
+RETURN 3;
+SHOW CREATE VIEW v3;
+View	Create View
+v3	CREATE ALGORITHM=UNDEFINED DEFINER=`a`@`` SQL SECURITY DEFINER VIEW `v3` AS select `t1`.`c` AS `c` from `t1`
+SHOW CREATE PROCEDURE p3;
+Procedure	sql_mode	Create Procedure
+p3		CREATE DEFINER=`a`@`` PROCEDURE `p3`()
+SELECT 3
+SHOW CREATE FUNCTION f3;
+Function	sql_mode	Create Function
+f3		CREATE DEFINER=`a`@`` FUNCTION `f3`() RETURNS int(11)
+RETURN 3
 DROP TRIGGER t1_bi;
 DROP TRIGGER ti_ai;
+DROP TRIGGER ti_bu;
 DROP VIEW v1;
 DROP VIEW v2;
+DROP VIEW v3;
 DROP TABLE t1;
+DROP PROCEDURE p1;
+DROP PROCEDURE p2;
+DROP PROCEDURE p3;
+DROP FUNCTION f1;
+DROP FUNCTION f2;
+DROP FUNCTION f3;

mysql-test/r/view_grant.result

@@ -520,11 +520,16 @@ use test;
 drop user mysqltest_1@localhost;
 drop database mysqltest;
 create definer=some_user@`` sql security invoker view v1 as select 1;
-ERROR HY000: Definer is not fully qualified
-create definer=some_user@localhost sql security invoker view v1 as select 1;
+Warnings:
+Note	1449	There is no 'some_user'@'' registered
+create definer=some_user@localhost sql security invoker view v2 as select 1;
 Warnings:
 Note	1449	There is no 'some_user'@'localhost' registered
 show create view v1;
 View	Create View
-v1	CREATE ALGORITHM=UNDEFINED DEFINER=`some_user`@`localhost` SQL SECURITY INVOKER VIEW `v1` AS select 1 AS `1`
+v1	CREATE ALGORITHM=UNDEFINED DEFINER=`some_user`@`` SQL SECURITY INVOKER VIEW `v1` AS select 1 AS `1`
+show create view v2;
+View	Create View
+v2	CREATE ALGORITHM=UNDEFINED DEFINER=`some_user`@`localhost` SQL SECURITY INVOKER VIEW `v2` AS select 1 AS `1`
 drop view v1;
+drop view v2;

mysql-test/t/skip_grants.test

 # This tests not performed with embedded server
 -- source include/not_embedded.inc
 
---disable_warnings
-drop table if exists t1,v1;
-drop view if exists t1,v1;
-drop procedure if exists f1;
---enable_warnings
 use test;
 
-#
-# Test that we can create and drop procedure without warnings
-# see bug#9993
-#
-create procedure f1() select 1;
-drop procedure f1;
-
-#
-# BUG#13504: creation view with DEFINER clause if --skip-grant-tables
-#
-create table t1 (a int);
-create definer='user'@'host' sql security definer view v1 as select * from t1;
-drop view v1;
-drop table t1;
-
-# BUG#17595: DROP FUNCTION IF EXISTS f1 crashes server
-drop function if exists f1;
-
 #
 # BUG#16777: Can not create trigger nor view w/o definer if --skip-grant-tables
 # specified
 #
-# Also, a test that we can create VIEW if privileges check switched off has
-# been moved here.
+# Also, the following test cases have been moved here:
+#   - test that we can create VIEW if privileges check switched off has been
+#     moved here;
+#   - test that we can create and drop procedure without warnings (BUG#9993);
+#   - BUG#17595: "DROP FUNCTION IF EXISTS" crashes server;
+#   - BUG#13504: creation view with DEFINER clause if --skip-grant-tables
 #
 
 # Prepare.
@@ -40,33 +21,90 @@ drop function if exists f1;
 
 DROP VIEW IF EXISTS v1;
 DROP VIEW IF EXISTS v2;
+DROP VIEW IF EXISTS v3;
 
 DROP TABLE IF EXISTS t1;
 
+DROP PROCEDURE IF EXISTS p1;
+DROP PROCEDURE IF EXISTS p2;
+DROP PROCEDURE IF EXISTS p3;
+
+DROP FUNCTION IF EXISTS f1;
+DROP FUNCTION IF EXISTS f2;
+DROP FUNCTION IF EXISTS f3;
+
 --enable_warnings
 
 # Test case.
 
 CREATE TABLE t1(c INT);
 
+# - try to create with implicit definer (definer would be ''@'');
+
 CREATE TRIGGER t1_bi BEFORE INSERT ON t1
   FOR EACH ROW
     SET @a = 1;
 
 CREATE VIEW v1 AS SELECT * FROM t1;
 
+CREATE PROCEDURE p1()
+  SELECT 1;
+
+CREATE FUNCTION f1() RETURNS INT
+  RETURN 1;
+
+# - try to create with explicit definer;
+
 CREATE DEFINER=a@b TRIGGER ti_ai AFTER INSERT ON t1
   FOR EACH ROW
     SET @b = 1;
 
 CREATE DEFINER=a@b VIEW v2 AS SELECT * FROM t1;
 
+CREATE DEFINER=a@b PROCEDURE p2()
+  SELECT 2;
+
+CREATE DEFINER=a@b FUNCTION f2() RETURNS INT
+  RETURN 2;
+
+# - try to create with explicit definer with empty host;
+
+CREATE DEFINER=a@'' TRIGGER ti_bu BEFORE UPDATE ON t1
+  FOR EACH ROW
+    SET @c = 1;
+
+CREATE DEFINER=a@'' VIEW v3 AS SELECT * FROM t1;
+
+CREATE DEFINER=a@'' PROCEDURE p3()
+  SELECT 3;
+
+CREATE DEFINER=a@'' FUNCTION f3() RETURNS INT
+  RETURN 3;
+
+# - check that empty host name is treated correctly;
+
+SHOW CREATE VIEW v3;
+
+SHOW CREATE PROCEDURE p3;
+
+SHOW CREATE FUNCTION f3;
+
 # Cleanup.
 
 DROP TRIGGER t1_bi;
 DROP TRIGGER ti_ai;
+DROP TRIGGER ti_bu;
 
 DROP VIEW v1;
 DROP VIEW v2;
+DROP VIEW v3;
 
 DROP TABLE t1;
+
+DROP PROCEDURE p1;
+DROP PROCEDURE p2;
+DROP PROCEDURE p3;
+
+DROP FUNCTION f1;
+DROP FUNCTION f2;
+DROP FUNCTION f3;

mysql-test/t/view_grant.test

@@ -706,10 +706,9 @@ connection default;
 #
 # DEFINER information check
 #
--- error ER_MALFORMED_DEFINER
 create definer=some_user@`` sql security invoker view v1 as select 1;
-create definer=some_user@localhost sql security invoker view v1 as select 1;
+create definer=some_user@localhost sql security invoker view v2 as select 1;
 show create view v1;
+show create view v2;
 drop view v1;
-
-
+drop view v2;

sql/sql_parse.cc

@@ -7300,8 +7300,7 @@ LEX_USER *create_default_definer(THD *thd)
 
 
 /*
-  Create definer with the given user and host names. Also check that the user
-  and host names satisfy definers requirements.
+  Create definer with the given user and host names.
 
   SYNOPSIS
     create_definer()
@@ -7319,14 +7318,6 @@ LEX_USER *create_definer(THD *thd, LEX_STRING *user_name, LEX_STRING *host_name)
 {
   LEX_USER *definer;
 
-  /* Check that specified host name is valid. */
-
-  if (host_name->length == 0)
-  {
-    my_error(ER_MALFORMED_DEFINER, MYF(0));
-    return 0;
-  }
-
   /* Create and initialize. */
 
   if (! (definer= (LEX_USER*) thd->alloc(sizeof(LEX_USER))))

sql/sql_show.cc

@@ -648,6 +648,18 @@ static const char *require_quotes(const char *name, uint name_length)
 }
 
 
+/*
+  Quote the given identifier if needed and append it to the target string.
+  If the given identifier is empty, it will be quoted.
+
+  SYNOPSIS
+  append_identifier()
+  thd                   thread handler
+  packet                target string
+  name                  the identifier to be appended
+  name_length           length of the appending identifier
+*/
+
 void
 append_identifier(THD *thd, String *packet, const char *name, uint length)
 {
@@ -701,8 +713,11 @@ append_identifier(THD *thd, String *packet, const char *name, uint length)
     length	length of name
 
   IMPLEMENTATION
-    If name is a keyword or includes a special character, then force
-    quoting.
+    Force quoting in the following cases:
+      - name is empty (for one, it is possible when we use this function for
+        quoting user and host names for DEFINER clause);
+      - name is a keyword;
+      - name includes a special character;
     Otherwise identifier is quoted only if the option OPTION_QUOTE_SHOW_CREATE
     is set.
 
@@ -713,7 +728,7 @@ append_identifier(THD *thd, String *packet, const char *name, uint length)
 
 int get_quote_char_for_identifier(THD *thd, const char *name, uint length)
 {
-  if (!length ||
+  if (length &&
       !is_keyword(name,length) &&
       !require_quotes(name, length) &&
       !(thd->options & OPTION_QUOTE_SHOW_CREATE))