MDEV-38451 SHOW FUNCTION CODE package_func crashes on the second execution

Routine name resolution performed on a temporary memory root
during execution. So on the second execution LEX::spname members
pointed to a cleared memory.

Fixing to peform the resolution to parse time, like the CALL statement does.
During the execution time LEX::spname members now stay untouched.

mysql-test/suite/compat/oracle/r/sp-package-code.result

@@ -243,3 +243,33 @@ Pos	Instruction
 7	jump 11
 DROP PACKAGE pkg1;
 DROP TABLE t1;
+# Start of 10.11 tests
+#
+# MDEV-38451 `SHOW FUNCTION CODE package_func` crashes on the second execution
+#
+CREATE PACKAGE pkg1 AS
+PROCEDURE p1();
+END;
+$$
+CREATE PACKAGE BODY pkg1 AS
+FUNCTION f1() RETURN INT AS
+BEGIN
+RETURN 10;
+END;
+PROCEDURE p1() AS
+BEGIN
+SHOW FUNCTION CODE f1;
+END;
+END;
+$$
+CALL pkg1.p1;
+Pos	Instruction
+0	freturn int 10
+CALL pkg1.p1;
+Pos	Instruction
+0	freturn int 10
+CALL pkg1.p1;
+Pos	Instruction
+0	freturn int 10
+DROP PACKAGE pkg1;
+# End of 10.11 tests

mysql-test/suite/compat/oracle/t/sp-package-code.test

@@ -180,3 +180,33 @@ SHOW PROCEDURE CODE pkg1.p1;
 SHOW PACKAGE BODY CODE pkg1;
 DROP PACKAGE pkg1;
 DROP TABLE t1;
+
+--echo # Start of 10.11 tests
+
+--echo #
+--echo # MDEV-38451 `SHOW FUNCTION CODE package_func` crashes on the second execution
+--echo #
+
+DELIMITER $$;
+CREATE PACKAGE pkg1 AS
+  PROCEDURE p1();
+END;
+$$
+CREATE PACKAGE BODY pkg1 AS
+  FUNCTION f1() RETURN INT AS
+  BEGIN
+    RETURN 10;
+  END;
+  PROCEDURE p1() AS
+  BEGIN
+    SHOW FUNCTION CODE f1;
+  END;
+END;
+$$
+DELIMITER ;$$
+CALL pkg1.p1;
+CALL pkg1.p1;
+CALL pkg1.p1;
+DROP PACKAGE pkg1;
+
+--echo # End of 10.11 tests

sql/sql_class.h

@@ -8120,6 +8120,8 @@ class Database_qualified_name
 public:
   LEX_CSTRING m_db;
   LEX_CSTRING m_name;
+  Database_qualified_name()
+  { }
   Database_qualified_name(const LEX_CSTRING *db, const LEX_CSTRING *name)
    :m_db(*db), m_name(*name)
   { }

sql/sql_cmd.h

@@ -180,4 +180,38 @@ public:
   }
 };
 
+
+#ifndef DBUG_OFF
+/**
+  Sql_cmd_call represents the SHOW CODE statement:
+  - SHOW PROCEDURE CODE
+  - SHOW FUNCTION CODE
+  - SHOW PACKAGE BODY CODE
+*/
+class Sql_cmd_show_routine_code : public Sql_cmd
+{
+public:
+  class sp_name *m_name;
+  const class Sp_handler *m_handler;
+  enum_sql_command m_sql_command;
+  Sql_cmd_show_routine_code(class sp_name *name,
+                            const class Sp_handler *handler,
+                            enum_sql_command sql_command)
+   :m_name(name),
+    m_handler(handler),
+    m_sql_command(sql_command)
+  {}
+
+  virtual ~Sql_cmd_show_routine_code() = default;
+
+  bool execute(THD *thd) override;
+
+  enum_sql_command sql_command_code() const override
+  {
+    return m_sql_command;
+  }
+};
+#endif // DBUG_OFF
+
+
 #endif // SQL_CMD_INCLUDED

sql/sql_lex.cc

@@ -9390,6 +9390,27 @@ bool LEX::add_create_view(THD *thd, DDL_options_st ddl,
 }
 
 
+bool LEX::show_routine_code_start(THD *thd, enum_sql_command cmd, sp_name *name)
+{
+#ifdef DBUG_OFF
+  my_error(ER_FEATURE_DISABLED, MYF(0),
+           "SHOW PROCEDURE|FUNCTION CODE", "--with-debug");
+  return true;
+#else
+  sql_command= cmd;
+  Database_qualified_name pkgname;
+  const Sp_handler *sph= Sp_handler::handler(cmd);
+  if (sph->sp_resolve_package_routine(thd, thd->lex->sphead,
+                                      name, &sph, &pkgname))
+    return true;
+  if (!(m_sql_cmd= new (thd->mem_root) Sql_cmd_show_routine_code(name, sph,
+                                                                 cmd)))
+    return true;
+  return false;
+#endif
+}
+
+
 bool LEX::call_statement_start(THD *thd, sp_name *name)
 {
   Database_qualified_name pkgname(&null_clex_str, &null_clex_str);

sql/sql_lex.h

@@ -3971,6 +3971,7 @@ public:
                                const sp_name *name,
                                const sp_name *name2,
                                const char *cpp_body_end);
+  bool show_routine_code_start(THD *thd, enum_sql_command cmd, sp_name *name);
   bool call_statement_start(THD *thd, sp_name *name);
   bool call_statement_start(THD *thd, const Lex_ident_sys_st *name);
   bool call_statement_start(THD *thd, const Lex_ident_sys_st *name1,

sql/sql_parse.cc

@@ -3288,6 +3288,24 @@ static bool prepare_db_action(THD *thd, privilege_t want_access,
 }
 
 
+#ifndef DBUG_OFF
+bool Sql_cmd_show_routine_code::execute(THD *thd)
+{
+  sp_head *sp;
+  if (m_handler->sp_cache_routine(thd, m_name, &sp))
+    return true;
+  if (!sp || sp->show_routine_code(thd))
+  {
+    /* We don't distinguish between errors for now */
+    my_error(ER_SP_DOES_NOT_EXIST, MYF(0),
+             m_handler->type_str(), m_name->m_name.str);
+    return true;
+  }
+  return false;
+}
+#endif // DBUG_OFF
+
+
 bool Sql_cmd_call::execute(THD *thd)
 {
   TABLE_LIST *all_tables= thd->lex->query_tables;
@@ -5967,34 +5985,6 @@ mysql_execute_command(THD *thd, bool is_called_from_prepared_stmt)
         goto error;
       break;
     }
-  case SQLCOM_SHOW_PROC_CODE:
-  case SQLCOM_SHOW_FUNC_CODE:
-  case SQLCOM_SHOW_PACKAGE_BODY_CODE:
-    {
-#ifndef DBUG_OFF
-      Database_qualified_name pkgname(&null_clex_str, &null_clex_str);
-      sp_head *sp;
-      const Sp_handler *sph= Sp_handler::handler(lex->sql_command);
-      WSREP_SYNC_WAIT(thd, WSREP_SYNC_WAIT_BEFORE_SHOW);
-      if (sph->sp_resolve_package_routine(thd, thd->lex->sphead,
-                                          lex->spname, &sph, &pkgname))
-        return true;
-      if (sph->sp_cache_routine(thd, lex->spname, &sp))
-        goto error;
-      if (!sp || sp->show_routine_code(thd))
-      {
-        /* We don't distinguish between errors for now */
-        my_error(ER_SP_DOES_NOT_EXIST, MYF(0),
-                 sph->type_str(), lex->spname->m_name.str);
-        goto error;
-      }
-      break;
-#else
-      my_error(ER_FEATURE_DISABLED, MYF(0),
-               "SHOW PROCEDURE|FUNCTION CODE", "--with-debug");
-      goto error;
-#endif // ifndef DBUG_OFF
-    }
   case SQLCOM_SHOW_CREATE_TRIGGER:
     {
       if (check_ident_length(&lex->spname->m_name))
@@ -6199,6 +6189,9 @@ mysql_execute_command(THD *thd, bool is_called_from_prepared_stmt)
   case SQLCOM_SIGNAL:
   case SQLCOM_RESIGNAL:
   case SQLCOM_GET_DIAGNOSTICS:
+  case SQLCOM_SHOW_PROC_CODE:
+  case SQLCOM_SHOW_FUNC_CODE:
+  case SQLCOM_SHOW_PACKAGE_BODY_CODE:
   case SQLCOM_CALL:
   case SQLCOM_REVOKE:
   case SQLCOM_GRANT:

sql/sql_yacc.yy

@@ -14024,23 +14024,25 @@ show_param:
           }
         | PROCEDURE_SYM CODE_SYM sp_name
           {
-            Lex->sql_command= SQLCOM_SHOW_PROC_CODE;
-            Lex->spname= $3;
+            if (Lex->show_routine_code_start(thd, SQLCOM_SHOW_PROC_CODE, $3))
+              MYSQL_YYABORT;
           }
         | FUNCTION_SYM CODE_SYM sp_name
           {
-            Lex->sql_command= SQLCOM_SHOW_FUNC_CODE;
-            Lex->spname= $3;
+            if (Lex->show_routine_code_start(thd, SQLCOM_SHOW_FUNC_CODE, $3))
+              MYSQL_YYABORT;
           }
         | PACKAGE_MARIADB_SYM BODY_MARIADB_SYM CODE_SYM sp_name
           {
-            Lex->sql_command= SQLCOM_SHOW_PACKAGE_BODY_CODE;
-            Lex->spname= $4;
+            if (Lex->show_routine_code_start(thd, SQLCOM_SHOW_PACKAGE_BODY_CODE,
+                                             $4))
+              MYSQL_YYABORT;
           }
         | PACKAGE_ORACLE_SYM BODY_ORACLE_SYM CODE_SYM sp_name
           {
-            Lex->sql_command= SQLCOM_SHOW_PACKAGE_BODY_CODE;
-            Lex->spname= $4;
+            if (Lex->show_routine_code_start(thd, SQLCOM_SHOW_PACKAGE_BODY_CODE,
+                                             $4))
+              MYSQL_YYABORT;
           }
         | CREATE EVENT_SYM sp_name
           {