MDEV-14116 INET6_NTOA output is set as null to varchar(39) variable

mysql-test/r/func_misc.result

@@ -1407,3 +1407,17 @@ SELECT CONCAT(NAME_CONST('name',15),'오');
 CONCAT(NAME_CONST('name',15),'오')
 15오
 SET NAMES latin1;
+#
+# MDEV-14116 INET6_NTOA output is set as null to varchar(39) variable
+#
+CREATE PROCEDURE p1()
+BEGIN
+DECLARE ip_full_addr varchar(39) DEFAULT "";
+SELECT INET6_NTOA(UNHEX('20000000000000000000000000000000')) into ip_full_addr;
+SELECT ip_full_addr;
+END;
+$$
+CALL p1();
+ip_full_addr
+2000::
+DROP PROCEDURE p1;

mysql-test/t/func_misc.test

@@ -1091,3 +1091,19 @@ SELECT COERCIBILITY(NAME_CONST('name',TIME'00:00:00'));
 SELECT COERCIBILITY(NAME_CONST('name',15));
 SELECT CONCAT(NAME_CONST('name',15),'오');
 SET NAMES latin1;
+
+--echo #
+--echo # MDEV-14116 INET6_NTOA output is set as null to varchar(39) variable
+--echo #
+
+DELIMITER $$;
+CREATE PROCEDURE p1()
+BEGIN
+  DECLARE ip_full_addr varchar(39) DEFAULT "";
+  SELECT INET6_NTOA(UNHEX('20000000000000000000000000000000')) into ip_full_addr;
+  SELECT ip_full_addr;
+END;
+$$
+DELIMITER ;$$
+CALL p1();
+DROP PROCEDURE p1;

sql/item_inetfunc.cc

@@ -181,7 +181,8 @@ String *Item_func_inet_str_base::val_str_ascii(String *buffer)
     return NULL;
   }
 
-  String *arg_str= args[0]->val_str(buffer);
+  StringBuffer<STRING_BUFFER_USUAL_SIZE> tmp;
+  String *arg_str= args[0]->val_str(&tmp);
   if (!arg_str) // Out-of memory happened. The error has been reported.
   {             // Or: the underlying field is NULL
     null_value= true;
@@ -679,7 +680,7 @@ static void ipv6_to_str(const in6_addr *ipv6, char *str)
   @retval true  The string has been converted sucessfully.
 */
 
-bool Item_func_inet6_aton::calc_value(String *arg, String *buffer)
+bool Item_func_inet6_aton::calc_value(const String *arg, String *buffer)
 {
   // ipv4-string -> varbinary(4)
   // ipv6-string -> varbinary(16)
@@ -719,7 +720,7 @@ bool Item_func_inet6_aton::calc_value(String *arg, String *buffer)
   @retval true  The string has been converted sucessfully.
 */
 
-bool Item_func_inet6_ntoa::calc_value(String *arg, String *buffer)
+bool Item_func_inet6_ntoa::calc_value(const String *arg, String *buffer)
 {
   if (arg->charset() != &my_charset_bin)
     return false;

sql/item_inetfunc.h

@@ -99,7 +99,7 @@ class Item_func_inet_str_base : public Item_str_ascii_func
   virtual String *val_str_ascii(String *buffer);
 
 protected:
-  virtual bool calc_value(String *arg, String *buffer) = 0;
+  virtual bool calc_value(const String *arg, String *buffer) = 0;
 };
 
 
@@ -126,7 +126,7 @@ class Item_func_inet6_aton : public Item_func_inet_str_base
   }
 
 protected:
-  virtual bool calc_value(String *arg, String *buffer);
+  virtual bool calc_value(const String *arg, String *buffer);
 };
 
 
@@ -158,7 +158,7 @@ class Item_func_inet6_ntoa : public Item_func_inet_str_base
   }
 
 protected:
-  virtual bool calc_value(String *arg, String *buffer);
+  virtual bool calc_value(const String *arg, String *buffer);
 };