Bug#44521 Executing a stored procedure as a prepared statement can sometimes cause

          an assertion in a debug build.

The reason is that the C API doesn't support multiple result sets for prepared
statements and attempting to execute a stored routine which returns multiple result
sets sometimes lead to a network error. The network error sets the diagnostic area
prematurely which later leads to the assert when an attempt is made to set a second
server state.

This patch fixes the issue by changing the scope of the error code returned by
sp_instr_stmt::execute() to include any error which happened during the execution.
To assure that Diagnostic_area::is_sent really mean that the message was sent all
network related functions are checked for return status.

libmysqld/lib_sql.cc:
  * Changed prototype to return success/failure status on net_send_error_packet(),
    net_send_ok(), net_send_eof(), write_eof_packet().
mysql-test/r/sp_notembedded.result:
  * Added test case for bug 44521
mysql-test/t/sp_notembedded.test:
  * Added test case for bug 44521
sql/protocol.cc:
  * Changed prototype to return success/failure status on net_send_error_packet(),
    net_send_ok(), net_send_eof(), write_eof_packet().
sql/protocol.h:
  * Changed prototype to return success/failure status on net_send_error_packet(),
    net_send_ok(), net_send_eof(), write_eof_packet().
sql/sp_head.cc:
  * Changed prototype to return success/failure status on net_send_error_packet(),
    net_send_ok(), net_send_eof(), write_eof_packet().

1 files changed, 2 insertions, 2 deletions

diff --git a/sql/sp_head.cc b/sql/sp_head.cc
index 018937fec2f..0736e5fc2a8 100644
--- a/sql/sp_head.cc
+++ b/sql/sp_head.cc
@@ -1248,7 +1248,7 @@ sp_head::execute(THD *thd)
     */
     if (thd->prelocked_mode == NON_PRELOCKED)
       thd->user_var_events_alloc= thd->mem_root;
-    
+
     err_status= i->execute(thd, &ip);
 
     if (i->free_list)
@@ -2863,7 +2863,7 @@ sp_instr_stmt::execute(THD *thd, uint *nextp)
     if (!thd->is_error())
       thd->main_da.reset_diagnostics_area();
   }
-  DBUG_RETURN(res);
+  DBUG_RETURN(res || thd->is_error());
 }