A fix and a test case for Bug#29050 Creation of a legal stored procedure

fails if a database is not selected prior.

The problem manifested itself when a user tried to
create a routine that had non-fully-qualified identifiers in its bodies
and there was no current database selected.

This is a regression introduced by the fix for Bug 19022:

The patch for Bug 19022 changes the code to always produce a warning
if we can't resolve the current database in the parser. 
In this case this was not necessary, since even though the produced
parsed tree was incorrect, we never re-use sphead
that was obtained at first parsing of CREATE PROCEDURE.
The sphead that is anyhow used is always obtained through db_load_routine,
and there we change the current database to sphead->m_db before
calling yyparse.

The idea of the fix is to resolve the current database directly using 
lex->sphead->m_db member when parsing a stored routine body, when
such is present.

This patch removes the need to reset the current database
when loading a trigger or routine definition into SP cache.
The redundant code will be removed in 5.1.

mysql-test/r/sp.result

@@ -6183,4 +6183,22 @@ call mysqltest_db1.sp_bug28551();
 show warnings;
 Level	Code	Message
 drop database mysqltest_db1;
+drop database if exists mysqltest_db1;
+drop table if exists test.t1;
+create database mysqltest_db1;
+use mysqltest_db1;
+drop database mysqltest_db1;
+create table test.t1 (id int);
+insert into test.t1 (id) values (1);
+create procedure test.sp_bug29050() begin select * from t1; end//
+show warnings;
+Level	Code	Message
+call test.sp_bug29050();
+id
+1
+show warnings;
+Level	Code	Message
+use test;
+drop procedure sp_bug29050;
+drop table t1;
 End of 5.0 tests

mysql-test/r/trigger.result

@@ -351,7 +351,7 @@ create trigger trg1 before insert on mysqltest.t1 for each row set @a:= 1;
 ERROR HY000: Trigger in wrong schema
 use mysqltest;
 create trigger test.trg1 before insert on t1 for each row set @a:= 1;
-ERROR HY000: Trigger in wrong schema
+ERROR 42S02: Table 'test.t1' doesn't exist
 drop database mysqltest;
 use test;
 create table t1 (i int, j int default 10, k int not null, key (k));
@@ -842,7 +842,7 @@ drop table t1;
 create trigger t1_bi before insert on test.t1 for each row set @a:=0;
 ERROR 3D000: No database selected
 create trigger test.t1_bi before insert on t1 for each row set @a:=0;
-ERROR 3D000: No database selected
+ERROR 42S02: Table 'test.t1' doesn't exist
 drop trigger t1_bi;
 ERROR 3D000: No database selected
 create table t1 (id int);

mysql-test/t/sp.test

@@ -7142,5 +7142,30 @@ create procedure mysqltest_db1.sp_bug28551() begin end;
 call mysqltest_db1.sp_bug28551();
 show warnings;
 drop database mysqltest_db1;
+#
+# Bug#29050 Creation of a legal stored procedure fails if a database is not
+# selected prior
+#
+--disable_warnings
+drop database if exists mysqltest_db1;
+drop table if exists test.t1;
+--enable_warnings
+create database mysqltest_db1;
+use mysqltest_db1;
+# For the sake of its side effect
+drop database mysqltest_db1; 
+# Now we have no current database selected.
+create table test.t1 (id int);
+insert into test.t1 (id) values (1);
+delimiter //;
+create procedure test.sp_bug29050() begin select * from t1; end//
+delimiter ;//
+show warnings;
+call test.sp_bug29050();
+show warnings;
+# Restore the old current database
+use test;
+drop procedure sp_bug29050;
+drop table t1;
 
 --echo End of 5.0 tests

mysql-test/t/trigger.test

@@ -406,7 +406,7 @@ create table mysqltest.t1 (i int);
 --error ER_TRG_IN_WRONG_SCHEMA
 create trigger trg1 before insert on mysqltest.t1 for each row set @a:= 1;
 use mysqltest;
---error ER_TRG_IN_WRONG_SCHEMA
+--error ER_NO_SUCH_TABLE
 create trigger test.trg1 before insert on t1 for each row set @a:= 1;
 drop database mysqltest;
 use test;
@@ -1040,7 +1040,7 @@ drop table t1;
 connection addconwithoutdb;
 --error ER_NO_DB_ERROR
 create trigger t1_bi before insert on test.t1 for each row set @a:=0;
---error ER_NO_DB_ERROR
+--error ER_NO_SUCH_TABLE
 create trigger test.t1_bi before insert on t1 for each row set @a:=0;
 --error ER_NO_DB_ERROR
 drop trigger t1_bi;

sql/sql_lex.cc

@@ -1974,6 +1974,43 @@ uint8 st_lex::get_effective_with_check(st_table_list *view)
 }
 
 
+/**
+  This method should be called only during parsing.
+  It is aware of compound statements (stored routine bodies)
+  and will initialize the destination with the default
+  database of the stored routine, rather than the default
+  database of the connection it is parsed in.
+  E.g. if one has no current database selected, or current database 
+  set to 'bar' and then issues:
+
+  CREATE PROCEDURE foo.p1() BEGIN SELECT * FROM t1 END//
+
+  t1 is meant to refer to foo.t1, not to bar.t1.
+
+  This method is needed to support this rule.
+
+  @return TRUE in case of error (parsing should be aborted, FALSE in
+  case of success
+*/
+
+bool
+st_lex::copy_db_to(char **p_db, uint *p_db_length) const
+{
+  if (sphead)
+  {
+    DBUG_ASSERT(sphead->m_db.str && sphead->m_db.length);
+    /*
+      It is safe to assign the string by-pointer, both sphead and
+      its statements reside in the same memory root.
+    */
+    *p_db= sphead->m_db.str;
+    if (p_db_length)
+      *p_db_length= sphead->m_db.length;
+    return FALSE;
+  }
+  return thd->copy_db_to(p_db, p_db_length);
+}
+
 /*
   initialize limit counters
 

sql/sql_lex.h

@@ -1237,6 +1237,8 @@ typedef struct st_lex : public Query_tables_list
     context_stack.pop();
   }
 
+  bool copy_db_to(char **p_db, uint *p_db_length) const;
+
   Name_resolution_context *current_context()
   {
     return context_stack.head();

sql/sql_parse.cc

@@ -6397,7 +6397,7 @@ TABLE_LIST *st_select_lex::add_table_to_list(THD *thd,
     ptr->db= table->db.str;
     ptr->db_length= table->db.length;
   }
-  else if (thd->copy_db_to(&ptr->db, &ptr->db_length))
+  else if (lex->copy_db_to(&ptr->db, &ptr->db_length))
     DBUG_RETURN(0);
 
   ptr->alias= alias_str;

sql/sql_yacc.yy

@@ -1565,14 +1565,14 @@ sp_name:
 	  }
 	| ident
 	  {
-            THD *thd= YYTHD;
+            LEX *lex= Lex;
             LEX_STRING db;
 	    if (check_routine_name($1))
             {
 	      my_error(ER_SP_WRONG_NAME, MYF(0), $1.str);
 	      MYSQL_YYABORT;
 	    }
-            if (thd->copy_db_to(&db.str, &db.length))
+            if (lex->copy_db_to(&db.str, &db.length))
               MYSQL_YYABORT;
 	    $$= new sp_name(db, $1, false);
             if ($$)
@@ -3624,10 +3624,9 @@ alter:
           opt_create_database_options
 	  {
 	    LEX *lex=Lex;
-            THD *thd= Lex->thd;
 	    lex->sql_command=SQLCOM_ALTER_DB;
 	    lex->name= $3;
-            if (lex->name == NULL && thd->copy_db_to(&lex->name, NULL))
+            if (lex->name == NULL && lex->copy_db_to(&lex->name, NULL))
               MYSQL_YYABORT;
 	  }
 	| ALTER PROCEDURE sp_name
@@ -3795,10 +3794,9 @@ alter_list_item:
 	| RENAME opt_to table_ident
 	  {
 	    LEX *lex=Lex;
-            THD *thd= lex->thd;
 	    lex->select_lex.db=$3->db.str;
             if (lex->select_lex.db == NULL &&
-                thd->copy_db_to(&lex->select_lex.db, NULL))
+                lex->copy_db_to(&lex->select_lex.db, NULL))
             {
               MYSQL_YYABORT;
             }
@@ -5148,7 +5146,7 @@ simple_expr:
             {
               THD *thd= lex->thd;
               LEX_STRING db;
-              if (thd->copy_db_to(&db.str, &db.length))
+              if (lex->copy_db_to(&db.str, &db.length))
                 MYSQL_YYABORT;
               sp_name *name= new sp_name(db, $1, false);
               if (name)
@@ -9025,8 +9023,7 @@ grant_ident:
 	'*'
 	  {
 	    LEX *lex= Lex;
-            THD *thd= lex->thd;
+            if (lex->copy_db_to(&lex->current_select->db, NULL))
-            if (thd->copy_db_to(&lex->current_select->db, NULL))
               MYSQL_YYABORT;
 	    if (lex->grant == GLOBAL_ACLS)
 	      lex->grant = DB_ACLS & ~GRANT_ACL;