Fix for bug #28464: a string argument to 'limit ?' PS - replication fails

Problem: we may get syntactically incorrect queries in the binary log 
if we use a string value user variable executing a PS which 
contains '... limit ?' clause, e.g.
prepare s from "select 1 limit ?"; 
set @a='qwe'; execute s using @a;
  
Fix: raise an error in such cases.


mysql-test/r/limit.result:
  Fix for bug #28464: a string argument to 'limit ?' PS - replication fails
    - test result
mysql-test/t/limit.test:
  Fix for bug #28464: a string argument to 'limit ?' PS - replication fails
    - test case
sql/item.cc:
  Fix for bug #28464: a string argument to 'limit ?' PS - replication fails
    - if Item_param::strict_type is set, check given and required types,
      return an error if not equal.
sql/item.h:
  Fix for bug #28464: a string argument to 'limit ?' PS - replication fails
    - bool strict_type introduced, which indicates that a parameter value must be of 
      the required_result_type type.
    - set_strict_type() function introduced to set required type.
sql/sql_yacc.yy:
  Fix for bug #28464: a string argument to 'limit ?' PS - replication fails
    - as we accept only INTs in the 'limit' clause set parameter's required type.

3 files changed, 14 insertions, 1 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 827c872adbc..155b2a962c8 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -2312,6 +2312,7 @@ default_set_param_func(Item_param *param,
 
 
 Item_param::Item_param(unsigned pos_in_query_arg) :
+  strict_type(FALSE),
   state(NO_VALUE),
   item_result_type(STRING_RESULT),
   /* Don't pretend to be a literal unless value for this item is set. */
@@ -2506,6 +2507,8 @@ bool Item_param::set_from_user_var(THD *thd, const user_var_entry *entry)
   if (entry && entry->value)
   {
     item_result_type= entry->type;
+    if (strict_type && required_result_type != item_result_type)
+      DBUG_RETURN(1);
     switch (entry->type) {
     case REAL_RESULT:
       set_double(*(double*)entry->value);
diff --git a/sql/item.h b/sql/item.h
index f38ce2f5db0..ced7586f099 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -1358,8 +1358,10 @@ class Item_param :public Item
   char cnvbuf[MAX_FIELD_WIDTH];
   String cnvstr;
   Item *cnvitem;
-public:
+  bool strict_type;
+  enum Item_result required_result_type;
 
+public:
   enum enum_item_param_state
   {
     NO_VALUE, NULL_VALUE, INT_VALUE, REAL_VALUE,
@@ -1487,6 +1489,11 @@ public:
     Otherwise return FALSE.
   */
   bool eq(const Item *item, bool binary_cmp) const;
+  void set_strict_type(enum Item_result result_type_arg)
+  {
+    strict_type= TRUE;
+    required_result_type= result_type_arg;
+  }
 };
 
 
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 4a50a602121..7c45d692d95 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -6216,6 +6216,9 @@ limit_options:
 	;
 limit_option:
         param_marker
+        {
+          ((Item_param *) $1)->set_strict_type(INT_RESULT);
+        }
         | ULONGLONG_NUM { $$= new Item_uint($1.str, $1.length); }
         | LONG_NUM     { $$= new Item_uint($1.str, $1.length); }
         | NUM           { $$= new Item_uint($1.str, $1.length); }