Fix for remaining issues described in Bug #1664

"mysql_send_long_data() API call is completely broken".

Now we are resetting some members (long_data_supplied/null_value...) of Item_param to its 
initial state after each execution of prepared statement. We also manipulating 
Item_param::maybe_null/null_value only via Item_param::set_* setters which makes code a bit 
more robust.


sql/item.cc:
  Now we are assuming that Item_param may be NULL until we know this fact exactly.
  Added non-empty implementation of Item_param::reset() method which should be used
  for restoring Item_param state after each statment execution. (We need to clear 
  long_data_supplied flag, we also clear some other Item_param members here since it
  makes code simpler.)
sql/item.h:
  Now Item_param::reset() method really does something.
sql/sql_prepare.cc:
  Now we are calling Item_param::reset() for each parameter after execution for resetting Item_param
  to initial state. So we no longer don't need Prepared_statement::long_data_flag. We also 
  set Item_param::null_value/maybe_null value in Item_param::set_* and reset() methods 
  instead of doing it explicitly in insert_params_* functions (this by the way lowers 
  probability that we will forget to update one of such functions).
tests/client_test.c:
  Added test for Bug#1664 "mysql_send_long_data() API call is broken".

1 files changed, 33 insertions, 1 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 72583ea02bb..44a05c42526 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -605,12 +605,19 @@ Item_param::Item_param(unsigned position) :
   set_param_func(default_set_param_func)
 {
   name= (char*) "?";
+  /* 
+    Since we can't say whenever this item can be NULL or cannot be NULL
+    before mysql_stmt_execute(), so we assuming that it can be NULL until
+    value is set.
+  */
+  maybe_null= 1;
 }
 
 void Item_param::set_null()
 {
   DBUG_ENTER("Item_param::set_null");
-  maybe_null= null_value= value_is_set= 1;
+  /* These are cleared after each execution by reset() method */
+  null_value= value_is_set= 1;
   DBUG_VOID_RETURN;
 }
 
@@ -620,6 +627,7 @@ void Item_param::set_int(longlong i)
   int_value= (longlong)i;
   item_type= INT_ITEM;
   value_is_set= 1;
+  maybe_null= 0;
   DBUG_PRINT("info", ("integer: %lld", int_value));
   DBUG_VOID_RETURN;
 }
@@ -630,6 +638,7 @@ void Item_param::set_double(double value)
   real_value=value;
   item_type= REAL_ITEM;
   value_is_set= 1;
+  maybe_null= 0;
   DBUG_PRINT("info", ("double: %lg", real_value));
   DBUG_VOID_RETURN;
 }
@@ -641,6 +650,7 @@ void Item_param::set_value(const char *str, uint length)
   str_value.copy(str,length,default_charset());
   item_type= STRING_ITEM;
   value_is_set= 1;
+  maybe_null= 0;
   DBUG_PRINT("info", ("string: %s", str_value.ptr()));
   DBUG_VOID_RETURN;
 }
@@ -665,6 +675,7 @@ void Item_param::set_time(TIME *tm, timestamp_type type)
   item_is_time= TRUE;
   item_type= STRING_ITEM;
   value_is_set= 1;
+  maybe_null= 0;
 }
 
 
@@ -673,6 +684,27 @@ void Item_param::set_longdata(const char *str, ulong length)
   str_value.append(str,length);
   long_data_supplied= 1;
   value_is_set= 1;
+  maybe_null= 0;
+}
+
+
+/*
+    Resets parameter after execution.
+  
+  SYNOPSIS
+     Item_param::reset()
+ 
+  NOTES
+    We clear null_value here instead of setting it in set_* methods, 
+    because we want more easily handle case for long data.
+*/
+
+void Item_param::reset()
+{  
+  str_value.set("", 0, &my_charset_bin);
+  value_is_set= long_data_supplied= 0;
+  maybe_null= 1;
+  null_value= 0;
 }