From 49d327ebf763dca23969ac4afe814617815d1411 Mon Sep 17 00:00:00 2001
From: Dmitry Shulga <Dmitry.Shulga@Sun.COM>
Date: Wed, 21 Jul 2010 14:56:43 +0700
Subject: [PATCH] Fixed bug #42496 - the server could crash on a debug assert
 after a failure to write into a closed socket

---
 sql/protocol.cc    | 15 +++++++++++----
 sql/sql_cache.cc   |  3 ++-
 sql/sql_cursor.cc  |  7 ++++++-
 sql/sql_prepare.cc |  7 +++++--
 4 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/sql/protocol.cc b/sql/protocol.cc
index dc53e029647..dfb78462f13 100644
--- a/sql/protocol.cc
+++ b/sql/protocol.cc
@@ -534,7 +534,11 @@ void Protocol::end_partial_result_set(THD *thd_arg)
 bool Protocol::flush()
 {
 #ifndef EMBEDDED_LIBRARY
-  return net_flush(&thd->net);
+  bool error;
+  thd->main_da.can_overwrite_status= TRUE;
+  error= net_flush(&thd->net);
+  thd->main_da.can_overwrite_status= FALSE;
+  return error;
 #else
   return 0;
 #endif
@@ -574,7 +578,8 @@ bool Protocol::send_fields(List<Item> *list, uint flags)
   if (flags & SEND_NUM_ROWS)
   {				// Packet with number of elements
     uchar *pos= net_store_length(buff, list->elements);
-    (void) my_net_write(&thd->net, buff, (size_t) (pos-buff));
+    if (my_net_write(&thd->net, buff, (size_t) (pos-buff)))
+      DBUG_RETURN(1);
   }
 
 #ifndef DBUG_OFF
@@ -698,7 +703,7 @@ bool Protocol::send_fields(List<Item> *list, uint flags)
     if (flags & SEND_DEFAULTS)
       item->send(&prot, &tmp);			// Send default value
     if (prot.write())
-      break;					/* purecov: inspected */
+      DBUG_RETURN(1);
 #ifndef DBUG_OFF
     field_types[count++]= field.type;
 #endif
@@ -711,7 +716,9 @@ bool Protocol::send_fields(List<Item> *list, uint flags)
       to show that there is no cursor.
       Send no warning information, as it will be sent at statement end.
     */
-    write_eof_packet(thd, &thd->net, thd->server_status, thd->total_warn_count);
+    if (write_eof_packet(thd, &thd->net, thd->server_status,
+                         thd->total_warn_count))
+      DBUG_RETURN(1);
   }
   DBUG_RETURN(prepare_for_send(list));
 
diff --git a/sql/sql_cache.cc b/sql/sql_cache.cc
index f862cbed4f1..fcf4edbdc22 100644
--- a/sql/sql_cache.cc
+++ b/sql/sql_cache.cc
@@ -1653,7 +1653,8 @@ def_week_frmt: %lu, in_trans: %d, autocommit: %d",
 
   thd->limit_found_rows = query->found_rows();
   thd->status_var.last_query_cost= 0.0;
-  thd->main_da.disable_status();
+  if (!thd->main_da.is_set())
+    thd->main_da.disable_status();
 
   BLOCK_UNLOCK_RD(query_block);
   DBUG_RETURN(1);				// Result sent to client
diff --git a/sql/sql_cursor.cc b/sql/sql_cursor.cc
index 6f61dc40f66..d7d029d28d4 100644
--- a/sql/sql_cursor.cc
+++ b/sql/sql_cursor.cc
@@ -658,7 +658,12 @@ void Materialized_cursor::fetch(ulong num_rows)
     if ((res= table->file->rnd_next(table->record[0])))
       break;
     /* Send data only if the read was successful. */
-    result->send_data(item_list);
+    /*
+      If network write failed (i.e. due to a closed socked),
+      the error has already been set. Just return.
+    */
+    if (result->send_data(item_list))
+      return;
   }
 
   switch (res) {
diff --git a/sql/sql_prepare.cc b/sql/sql_prepare.cc
index 041d9f7c30b..bd152866deb 100644
--- a/sql/sql_prepare.cc
+++ b/sql/sql_prepare.cc
@@ -263,8 +263,11 @@ static bool send_prep_stmt(Prepared_statement *stmt, uint columns)
                                           &stmt->lex->param_list,
                                           Protocol::SEND_EOF);
   }
-  /* Flag that a response has already been sent */
-  thd->main_da.disable_status();
+
+  if (!error)
+    /* Flag that a response has already been sent */
+    thd->main_da.disable_status();
+
   DBUG_RETURN(error);
 }
 #else