A fix and a test case for Bug#10794 "mysql_stmt_attr_set no

open cursor after mysql_stmt_execute" + post-review fixes.
The bug was caused by wrong flags in stmt->server_status on the client
side: if there was no cursor, the server didn't send server_status
flags to the client, and the old flags were used to set up the
fetch function of a statement. Consequently, stmt_read_row_from_cursor was
used when there was no cursor. The fix fixes the server to always
send server flags to the client.


include/mysql_com.h:
  Update stale comments.
libmysql/libmysql.c:
  Remove an extra assignment.
libmysqld/lib_sql.cc:
  Update to correspond to the changed signature of send_eof
sql/protocol.cc:
  Actual fix for bug#10794: create a function that writes the eof
  packet to network and use it from send_fields. We need to send
  a full eof packet from send_fields to inform the client about
  the cursor status (that there is no cursor in this case).
sql/protocol.h:
  Remove an unused parameter for send_eof.
tests/mysql_client_test.c:
  A test case for Bug#10794 "mysql_stmt_attr_set no open cursor 
  after mysql_stmt_execute"

include/mysql_com.h

@@ -137,14 +137,14 @@ enum enum_server_command
 #define SERVER_QUERY_NO_GOOD_INDEX_USED 16
 #define SERVER_QUERY_NO_INDEX_USED      32
 /*
-  The server was able to fulfill client request and open read-only
-  non-scrollable cursor for the query.  This flag comes in server
-  status with reply to COM_EXECUTE and COM_EXECUTE_DIRECT commands.
+  The server was able to fulfill the clients request and opened a
+  read-only non-scrollable cursor for a query. This flag comes
+  in reply to COM_STMT_EXECUTE and COM_STMT_FETCH commands.
 */
 #define SERVER_STATUS_CURSOR_EXISTS 64
 /*
-  This flag is sent with last row of read-only cursor, in reply to
-  COM_FETCH command.
+  This flag is sent when a read-only cursor is exhausted, in reply to
+  COM_STMT_FETCH command.
 */
 #define SERVER_STATUS_LAST_ROW_SENT 128
 #define SERVER_STATUS_DB_DROPPED        256 /* A database was dropped */

libmysql/libmysql.c

@@ -2726,7 +2726,6 @@ stmt_read_row_from_cursor(MYSQL_STMT *stmt, unsigned char **row)
       set_stmt_errmsg(stmt, net->last_error, net->last_errno, net->sqlstate);
       return 1;
     }
-    stmt->server_status= mysql->server_status;
     if (cli_read_binary_rows(stmt))
       return 1;
     stmt->server_status= mysql->server_status;

libmysqld/lib_sql.cc

@@ -773,7 +773,7 @@ send_ok(THD *thd,ha_rows affected_rows,ulonglong id,const char *message)
 }
 
 void
-send_eof(THD *thd, bool no_flush)
+send_eof(THD *thd)
 {
 }
 

sql/protocol.cc

@@ -28,6 +28,7 @@
 #include <stdarg.h>
 
 static const unsigned int PACKET_BUFFER_EXTRA_ALLOC= 1024;
+static void write_eof_packet(THD *thd, NET *net);
 
 #ifndef EMBEDDED_LIBRARY
 bool Protocol::net_store_data(const char *from, uint length)
@@ -362,43 +363,52 @@ static char eof_buff[1]= { (char) 254 };        /* Marker for end of fields */
 */    
 
 void
-send_eof(THD *thd, bool no_flush)
+send_eof(THD *thd)
 {
   NET *net= &thd->net;
   DBUG_ENTER("send_eof");
   if (net->vio != 0 && !net->no_send_eof)
   {
-    if (thd->client_capabilities & CLIENT_PROTOCOL_41)
-    {
-      uchar buff[5];
-      /* Don't send warn count during SP execution, as the warn_list
-         is cleared between substatements, and mysqltest gets confused */
-      uint tmp= (thd->spcont ? 0 : min(thd->total_warn_count, 65535));
-      buff[0]=254;
-      int2store(buff+1, tmp);
-      /*
-	The following test should never be true, but it's better to do it
-	because if 'is_fatal_error' is set the server is not going to execute
-	other queries (see the if test in dispatch_command / COM_QUERY)
-      */
-      if (thd->is_fatal_error)
-	thd->server_status&= ~SERVER_MORE_RESULTS_EXISTS;
-      int2store(buff+3, thd->server_status);
-      VOID(my_net_write(net,(char*) buff,5));
-      VOID(net_flush(net));
-    }
-    else
-    {
-      VOID(my_net_write(net,eof_buff,1));
-      if (!no_flush)
-	VOID(net_flush(net));
-    }
+    write_eof_packet(thd, net);
+    VOID(net_flush(net));
     thd->net.no_send_error= 1;
     DBUG_PRINT("info", ("EOF sent, so no more error sending allowed"));
   }
   DBUG_VOID_RETURN;
 }
 
+
+/*
+  Format EOF packet according to the current protocol and
+  write it to the network output buffer.
+*/
+
+static void write_eof_packet(THD *thd, NET *net)
+{
+  if (thd->client_capabilities & CLIENT_PROTOCOL_41)
+  {
+    uchar buff[5];
+    /*
+      Don't send warn count during SP execution, as the warn_list
+      is cleared between substatements, and mysqltest gets confused
+    */
+    uint tmp= (thd->spcont ? 0 : min(thd->total_warn_count, 65535));
+    buff[0]= 254;
+    int2store(buff+1, tmp);
+    /*
+      The following test should never be true, but it's better to do it
+      because if 'is_fatal_error' is set the server is not going to execute
+      other queries (see the if test in dispatch_command / COM_QUERY)
+    */
+    if (thd->is_fatal_error)
+      thd->server_status&= ~SERVER_MORE_RESULTS_EXISTS;
+    int2store(buff+3, thd->server_status);
+    VOID(my_net_write(net, (char*) buff, 5));
+  }
+  else
+    VOID(my_net_write(net, eof_buff, 1));
+}
+
 /*
     Please client to send scrambled_password in old format.
   SYNOPSYS
@@ -640,7 +650,7 @@ bool Protocol::send_fields(List<Item> *list, uint flags)
   }
 
   if (flags & SEND_EOF)
-    my_net_write(&thd->net, eof_buff, 1);
+    write_eof_packet(thd, &thd->net);
   DBUG_RETURN(prepare_for_send(list));
 
 err:

sql/protocol.h

@@ -179,7 +179,7 @@ void net_printf_error(THD *thd, uint sql_errno, ...);
 void net_send_error(THD *thd, uint sql_errno=0, const char *err=0);
 void send_ok(THD *thd, ha_rows affected_rows=0L, ulonglong id=0L,
 	     const char *info=0);
-void send_eof(THD *thd, bool no_flush=0);
+void send_eof(THD *thd);
 bool send_old_password_request(THD *thd);
 char *net_store_length(char *packet,uint length);
 char *net_store_data(char *to,const char *from, uint length);

tests/mysql_client_test.c

@@ -13389,6 +13389,93 @@ static void test_bug10736()
   myquery(rc);
 }
 
+/* Bug#10794: cursors, packets out of order */
+
+static void test_bug10794()
+{
+  MYSQL_STMT *stmt, *stmt1;
+  MYSQL_BIND bind[2];
+  char a[21];
+  int id_val;
+  ulong a_len;
+  int rc;
+  const char *stmt_text;
+  int i= 0;
+  ulong type;
+
+  myheader("test_bug10794");
+
+  mysql_query(mysql, "drop table if exists t1");
+  mysql_query(mysql, "create table t1 (id integer not null primary key,"
+                                      "name varchar(20) not null)");
+  stmt= mysql_stmt_init(mysql);
+  stmt_text= "insert into t1 (id, name) values (?, ?)";
+  rc= mysql_stmt_prepare(stmt, stmt_text, strlen(stmt_text));
+  check_execute(stmt, rc);
+  bzero(bind, sizeof(bind));
+  bind[0].buffer_type= MYSQL_TYPE_LONG;
+  bind[0].buffer= (void*) &id_val;
+  bind[1].buffer_type= MYSQL_TYPE_STRING;
+  bind[1].buffer= (void*) a;
+  bind[1].length= &a_len;
+  rc= mysql_stmt_bind_param(stmt, bind);
+  check_execute(stmt, rc);
+  for (i= 0; i < 34; i++)
+  {
+    id_val= (i+1)*10;
+    sprintf(a, "a%d", i);
+    a_len= strlen(a); /* safety against broken sprintf */
+    rc= mysql_stmt_execute(stmt);
+    check_execute(stmt, rc);
+  }
+  stmt_text= "select name from t1";
+  rc= mysql_stmt_prepare(stmt, stmt_text, strlen(stmt_text));
+  type= (ulong) CURSOR_TYPE_READ_ONLY;
+  mysql_stmt_attr_set(stmt, STMT_ATTR_CURSOR_TYPE, (const void*) &type);
+  stmt1= mysql_stmt_init(mysql);
+  mysql_stmt_attr_set(stmt1, STMT_ATTR_CURSOR_TYPE, (const void*) &type);
+  bzero(bind, sizeof(bind));
+  bind[0].buffer_type= MYSQL_TYPE_STRING;
+  bind[0].buffer= (void*) a;
+  bind[0].buffer_length= sizeof(a);
+  bind[0].length= &a_len;
+  rc= mysql_stmt_bind_result(stmt, bind);
+  check_execute(stmt, rc);
+  rc= mysql_stmt_execute(stmt);
+  check_execute(stmt, rc);
+  rc= mysql_stmt_fetch(stmt);
+  check_execute(stmt, rc);
+  if (!opt_silent)
+    printf("Fetched row from stmt: %s\n", a);
+  /* Don't optimize: an attribute of the original test case */
+  mysql_stmt_free_result(stmt);
+  mysql_stmt_reset(stmt);
+  stmt_text= "select name from t1 where id=10";
+  rc= mysql_stmt_prepare(stmt1, stmt_text, strlen(stmt_text));
+  check_execute(stmt1, rc);
+  rc= mysql_stmt_bind_result(stmt1, bind);
+  check_execute(stmt1, rc);
+  rc= mysql_stmt_execute(stmt1);
+  while (1)
+  {
+    rc= mysql_stmt_fetch(stmt1);
+    if (rc == MYSQL_NO_DATA)
+    {
+      if (!opt_silent)
+        printf("End of data in stmt1\n");
+      break;
+    }
+    check_execute(stmt1, rc);
+    if (!opt_silent)
+      printf("Fetched row from stmt1: %s\n", a);
+  }
+  mysql_stmt_close(stmt);
+  mysql_stmt_close(stmt1);
+
+  rc= mysql_query(mysql, "drop table t1");
+  myquery(rc);
+}
+
 
 /*
   Read and parse arguments and MySQL options from my.cnf
@@ -13626,6 +13713,7 @@ static struct my_tests_st my_tests[]= {
   { "test_bug11111", test_bug11111 },
   { "test_bug9992", test_bug9992 },
   { "test_bug10736", test_bug10736 },
+  { "test_bug10794", test_bug10794 },
   { 0, 0 }
 };