Bug#35103 mysql_client_test::test_bug29948 causes sporadic failures

The problem was that the COM_STMT_SEND_LONG_DATA was sending a response
packet if the prepared statement wasn't found in the server (due to
reconnection). The commands COM_STMT_SEND_LONG_DATA and COM_STMT_CLOSE
should not send any packets, even error packets should not be sent since
they are not expected by the client API.

The solution is to clear generated during the execution of the aforementioned
commands and to skip resend of prepared statement commands. Another fix is
that if the connection breaks during the send of prepared statement command,
the command is not sent again since the prepared statement is no longer in the
server.

libmysql/libmysql.c

@@ -2456,7 +2456,7 @@ static my_bool execute(MYSQL_STMT *stmt, char *packet, ulong length)
   int4store(buff+5, 1);                         /* iteration count */
 
   res= test(cli_advanced_command(mysql, COM_STMT_EXECUTE, buff, sizeof(buff),
-                                 packet, length, 1, NULL) ||
+                                 packet, length, 1, stmt) ||
             (*mysql->methods->read_query_result)(mysql));
   stmt->affected_rows= mysql->affected_rows;
   stmt->server_status= mysql->server_status;
@@ -2673,7 +2673,7 @@ stmt_read_row_from_cursor(MYSQL_STMT *stmt, unsigned char **row)
     int4store(buff + 4, stmt->prefetch_rows); /* number of rows to fetch */
     if ((*mysql->methods->advanced_command)(mysql, COM_STMT_FETCH,
                                             buff, sizeof(buff), NullS, 0,
-                                            1, NULL))
+                                            1, stmt))
     {
       set_stmt_errmsg(stmt, net->last_error, net->last_errno, net->sqlstate);
       return 1;
@@ -3340,7 +3340,7 @@ mysql_stmt_send_long_data(MYSQL_STMT *stmt, uint param_number,
     */
     if ((*mysql->methods->advanced_command)(mysql, COM_STMT_SEND_LONG_DATA,
                                             buff, sizeof(buff), data,
-                                            length, 1, NULL))
+                                            length, 1, stmt))
     {
       set_stmt_errmsg(stmt, mysql->net.last_error,
 		      mysql->net.last_errno, mysql->net.sqlstate);
@@ -4737,6 +4737,13 @@ int STDCALL mysql_stmt_store_result(MYSQL_STMT *stmt)
   MYSQL_DATA *result= &stmt->result;
   DBUG_ENTER("mysql_stmt_store_result");
 
+  if (!mysql)
+  {
+    /* mysql can be reset in mysql_close called from mysql_reconnect */
+    set_stmt_error(stmt, CR_SERVER_LOST, unknown_sqlstate);
+    DBUG_RETURN(1);
+  }
+
   mysql= mysql->last_used_con;
 
   if (!stmt->field_count)
@@ -4762,7 +4769,7 @@ int STDCALL mysql_stmt_store_result(MYSQL_STMT *stmt)
     int4store(buff, stmt->stmt_id);
     int4store(buff + 4, (int)~0); /* number of rows to fetch */
     if (cli_advanced_command(mysql, COM_STMT_FETCH, buff, sizeof(buff),
-                             NullS, 0, 1, NULL))
+                             NullS, 0, 1, stmt))
     {
       set_stmt_errmsg(stmt, net->last_error, net->last_errno, net->sqlstate);
       DBUG_RETURN(1);
@@ -4949,7 +4956,7 @@ static my_bool reset_stmt_handle(MYSQL_STMT *stmt, uint flags)
         char buff[MYSQL_STMT_HEADER]; /* packet header: 4 bytes for stmt id */
         int4store(buff, stmt->stmt_id);
         if ((*mysql->methods->advanced_command)(mysql, COM_STMT_RESET, buff,
-                                                sizeof(buff), 0, 0, 0, NULL))
+                                                sizeof(buff), 0, 0, 0, stmt))
         {
           set_stmt_errmsg(stmt, mysql->net.last_error, mysql->net.last_errno,
                           mysql->net.sqlstate);

sql-common/client.c

@@ -665,11 +665,12 @@ my_bool
 cli_advanced_command(MYSQL *mysql, enum enum_server_command command,
 		     const char *header, ulong header_length,
 		     const char *arg, ulong arg_length, my_bool skip_check,
-                     MYSQL_STMT *stmt __attribute__((unused)))
+                     MYSQL_STMT *stmt)
 {
   NET *net= &mysql->net;
   my_bool result= 1;
   init_sigpipe_variables
+  my_bool stmt_skip= stmt ? stmt->state != MYSQL_STMT_INIT_DONE : FALSE;
   DBUG_ENTER("cli_advanced_command");
 
   /* Don't give sigpipe errors if the client doesn't want them */
@@ -677,7 +678,7 @@ cli_advanced_command(MYSQL *mysql, enum enum_server_command command,
 
   if (mysql->net.vio == 0)
   {						/* Do reconnect if possible */
-    if (mysql_reconnect(mysql))
+    if (mysql_reconnect(mysql) || stmt_skip)
       DBUG_RETURN(1);
   }
   if (mysql->status != MYSQL_STATUS_READY ||
@@ -708,7 +709,7 @@ cli_advanced_command(MYSQL *mysql, enum enum_server_command command,
       goto end;
     }
     end_server(mysql);
-    if (mysql_reconnect(mysql))
+    if (mysql_reconnect(mysql) || stmt_skip)
       goto end;
     if (net_write_command(net,(uchar) command, header, header_length,
 			  arg, arg_length))
@@ -2503,6 +2504,9 @@ my_bool mysql_reconnect(MYSQL *mysql)
       if (stmt->state != MYSQL_STMT_INIT_DONE)
       {
         stmt->mysql= 0;
+        stmt->last_errno= CR_SERVER_LOST;
+        strmov(stmt->last_error, ER(CR_SERVER_LOST));
+        strmov(stmt->sqlstate, unknown_sqlstate);
       }
       else
       {

sql/sql_prepare.cc

@@ -2516,7 +2516,7 @@ void mysql_stmt_close(THD *thd, char *packet)
   DBUG_ENTER("mysql_stmt_close");
 
   if (!(stmt= find_prepared_statement(thd, stmt_id, "mysql_stmt_close")))
-    DBUG_VOID_RETURN;
+    goto out;
 
   /*
     The only way currently a statement can be deallocated when it's
@@ -2525,6 +2525,9 @@ void mysql_stmt_close(THD *thd, char *packet)
   DBUG_ASSERT(! (stmt->flags & (uint) Prepared_statement::IS_IN_USE));
   (void) stmt->deallocate();
 
+out:
+  /* clear errors, response packet is not expected */
+  thd->clear_error();
   DBUG_VOID_RETURN;
 }
 
@@ -2591,10 +2594,7 @@ void mysql_stmt_get_longdata(THD *thd, char *packet, ulong packet_length)
 #ifndef EMBEDDED_LIBRARY
   /* Minimal size of long data packet is 6 bytes */
   if (packet_length <= MYSQL_LONG_DATA_HEADER)
-  {
-    my_error(ER_WRONG_ARGUMENTS, MYF(0), "mysql_stmt_send_long_data");
-    DBUG_VOID_RETURN;
-  }
+    goto out;
 #endif
 
   stmt_id= uint4korr(packet);
@@ -2614,7 +2614,7 @@ void mysql_stmt_get_longdata(THD *thd, char *packet, ulong packet_length)
     stmt->last_errno= ER_WRONG_ARGUMENTS;
     sprintf(stmt->last_error, ER(ER_WRONG_ARGUMENTS),
             "mysql_stmt_send_long_data");
-    DBUG_VOID_RETURN;
+    goto out;
   }
 #endif
 
@@ -2630,6 +2630,10 @@ void mysql_stmt_get_longdata(THD *thd, char *packet, ulong packet_length)
     stmt->last_errno= ER_OUTOFMEMORY;
     sprintf(stmt->last_error, ER(ER_OUTOFMEMORY), 0);
   }
+
+out:
+  /* clear errors, response packet is not expected */
+  thd->clear_error();
   DBUG_VOID_RETURN;
 }
 

tests/mysql_client_test.c

@@ -11746,6 +11746,7 @@ static void test_bug5194()
 
     rc= mysql_stmt_execute(stmt);
     check_execute(stmt, rc);
+    mysql_stmt_reset(stmt);
   }
 
   mysql_stmt_close(stmt);
@@ -15942,83 +15943,6 @@ static void test_bug27592()
   DBUG_VOID_RETURN;
 }
 
-#if 0
-
-static void test_bug29948()
-{
-  MYSQL *dbc=NULL;
-  MYSQL_STMT *stmt=NULL;
-  MYSQL_BIND bind;
-
-  int res=0;
-  my_bool auto_reconnect=1, error=0, is_null=0;
-  char kill_buf[20];
-  const char *query;
-  int buf;
-  unsigned long length, cursor_type;
-  
-  dbc = mysql_init(NULL);
-  DIE_UNLESS(dbc);
-
-  mysql_options(dbc, MYSQL_OPT_RECONNECT, (char*)&auto_reconnect);
-  if (!mysql_real_connect(dbc, opt_host, opt_user,
-                           opt_password, current_db, opt_port,
-                           opt_unix_socket,
-                          (CLIENT_FOUND_ROWS | CLIENT_MULTI_STATEMENTS |
-                           CLIENT_MULTI_RESULTS)))
-  {
-    printf("connection failed: %s (%d)", mysql_error(dbc),
-           mysql_errno(dbc));
-    exit(1);
-  }
-
-  bzero(&bind, sizeof(bind));
-  bind.buffer_type= MYSQL_TYPE_LONG;
-  bind.buffer= (char *)&buf;
-  bind.is_null= &is_null;
-  bind.error= &error;
-  bind.length= &length;
-
-  res= mysql_query(dbc, "DROP TABLE IF EXISTS t1");
-  myquery(res);
-  res= mysql_query(dbc, "CREATE TABLE t1 (a INT)");
-  myquery(res);
-  res= mysql_query(dbc, "INSERT INTO t1 VALUES(1)");
-  myquery(res);
-
-  stmt= mysql_stmt_init(dbc);
-  check_stmt(stmt);
-
-  cursor_type= CURSOR_TYPE_READ_ONLY;
-  res= mysql_stmt_attr_set(stmt, STMT_ATTR_CURSOR_TYPE, (void *)&cursor_type);
-  myquery(res);
-
-  query= "SELECT * from t1 where a=?";
-  res= mysql_stmt_prepare(stmt, query, strlen(query));
-  myquery(res);
-
-  res= mysql_stmt_bind_param(stmt, &bind);
-  myquery(res);
-
-  res= mysql_stmt_execute(stmt);
-  check_execute(stmt, res);
-
-  res= mysql_stmt_bind_result(stmt,&bind);
-  check_execute(stmt, res);
-    
-  sprintf(kill_buf, "kill %ld", dbc->thread_id);
-  mysql_query(dbc, kill_buf);
-
-  res= mysql_stmt_store_result(stmt);
-  DIE_UNLESS(res);
-
-  mysql_stmt_free_result(stmt);
-  mysql_stmt_close(stmt);
-  mysql_query(dbc, "DROP TABLE t1");
-  mysql_close(dbc);
-}
-
-#endif
 
 /**
   Bug#29306 Truncated data in MS Access with decimal (3,1) columns in a VIEW
@@ -16546,7 +16470,6 @@ static struct my_tests_st my_tests[]= {
   { "test_bug28505", test_bug28505 },
   { "test_bug28934", test_bug28934 },
   { "test_bug27592", test_bug27592 },
-  /* { "test_bug29948", test_bug29948 }, Bug#35103 */
   { "test_bug29306", test_bug29306 },
   { "test_bug31669", test_bug31669 },
   { "test_bug32265", test_bug32265 },