MDEV-12687 Split Item::send() into virtual method in Type_handler

1 files changed, 11 insertions, 11 deletions

diff --git a/sql/protocol.cc b/sql/protocol.cc
index 340b3a2176a..33742dc01a2 100644
--- a/sql/protocol.cc
+++ b/sql/protocol.cc
@@ -791,8 +791,7 @@ bool Protocol::send_result_set_metadata(List<Item> *list, uint flags)
 {
   List_iterator_fast<Item> it(*list);
   Item *item;
-  uchar buff[MAX_FIELD_WIDTH];
-  String tmp((char*) buff,sizeof(buff),&my_charset_bin);
+  ValueBuffer<MAX_FIELD_WIDTH> tmp;
   Protocol_text prot(thd);
   String *local_packet= prot.storage_packet();
   CHARSET_INFO *thd_charset= thd->variables.character_set_results;
@@ -800,7 +799,9 @@ bool Protocol::send_result_set_metadata(List<Item> *list, uint flags)
 
   if (flags & SEND_NUM_ROWS)
   {				// Packet with number of elements
+    uchar buff[MAX_INT_WIDTH];
     uchar *pos= net_store_length(buff, list->elements);
+    DBUG_ASSERT(pos <= buff + sizeof(buff));
     if (my_net_write(&thd->net, buff, (size_t) (pos-buff)))
       DBUG_RETURN(1);
   }
@@ -968,15 +969,20 @@ bool Protocol::write()
 
 bool Protocol::send_result_set_row(List<Item> *row_items)
 {
-  char buffer[MAX_FIELD_WIDTH];
-  String str_buffer(buffer, sizeof (buffer), &my_charset_bin);
   List_iterator_fast<Item> it(*row_items);
 
   DBUG_ENTER("Protocol::send_result_set_row");
 
   for (Item *item= it++; item; item= it++)
   {
-    if (item->send(this, &str_buffer))
+    /*
+      ValueBuffer::m_string can be altered during Item::send().
+      It's important to declare value_buffer inside the loop,
+      to have ValueBuffer::m_string point to ValueBuffer::buffer
+      on every iteration.
+    */
+    ValueBuffer<MAX_FIELD_WIDTH> value_buffer;
+    if (item->send(this, &value_buffer))
     {
       // If we're out of memory, reclaim some, to help us recover.
       this->free();
@@ -985,12 +991,6 @@ bool Protocol::send_result_set_row(List<Item> *row_items)
     /* Item::send() may generate an error. If so, abort the loop. */
     if (thd->is_error())
       DBUG_RETURN(TRUE);
-
-    /*
-      Reset str_buffer to its original state, as it may have been altered in
-      Item::send().
-    */
-    str_buffer.set(buffer, sizeof(buffer), &my_charset_bin);
   }
 
   DBUG_RETURN(FALSE);