Bug #29804 UDF parameters don't contain correct string length

Previously, UDF *_init functions were passed constant strings with erroneous lengths.
The length came from the containing variable's size, not the length of the value itself.

Now the *_init functions get the constant as a null terminated string with the correct
length supplied.

mysql-test/r/udf.result

@@ -334,4 +334,28 @@ Qcache_queries_in_cache	0
 drop table t1;
 drop function metaphon;
 set GLOBAL query_cache_size=default;
+CREATE TABLE const_len_bug (
+str_const varchar(4000),
+result1 varchar(4000),
+result2 varchar(4000)
+);
+CREATE TRIGGER check_const_len_trigger BEFORE INSERT ON const_len_bug FOR EACH ROW BEGIN
+set NEW.str_const = 'bar';
+set NEW.result2 = check_const_len(NEW.str_const);
+END |
+CREATE PROCEDURE check_const_len_sp (IN str_const VARCHAR(4000))
+BEGIN
+DECLARE result VARCHAR(4000);
+SET result = check_const_len(str_const);
+insert into const_len_bug values(str_const, result, "");
+END |
+CREATE FUNCTION check_const_len RETURNS string SONAME "UDF_EXAMPLE_LIB";
+CALL check_const_len_sp("foo");
+SELECT * from const_len_bug;
+str_const	result1	result2
+bar	Correct length	Correct length
+DROP FUNCTION check_const_len;
+DROP PROCEDURE check_const_len_sp;
+DROP TRIGGER check_const_len_trigger;
+DROP TABLE const_len_bug;
 End of 5.0 tests.

mysql-test/t/udf.test

@@ -364,4 +364,40 @@ drop function metaphon;
 set GLOBAL query_cache_size=default;
 
 
+#
+# Bug #29804  UDF parameters don't contain correct string length
+#
+
+CREATE TABLE const_len_bug (
+  str_const varchar(4000),
+  result1 varchar(4000),
+  result2 varchar(4000)
+);
+
+DELIMITER |;
+CREATE TRIGGER check_const_len_trigger BEFORE INSERT ON const_len_bug FOR EACH ROW BEGIN
+   set NEW.str_const = 'bar';
+   set NEW.result2 = check_const_len(NEW.str_const);
+END |
+
+CREATE PROCEDURE check_const_len_sp (IN str_const VARCHAR(4000))
+BEGIN
+DECLARE result VARCHAR(4000);
+SET result = check_const_len(str_const);
+insert into const_len_bug values(str_const, result, "");
+END |
+DELIMITER ;|
+
+--replace_result $UDF_EXAMPLE_LIB UDF_EXAMPLE_LIB
+eval CREATE FUNCTION check_const_len RETURNS string SONAME "$UDF_EXAMPLE_LIB";
+
+CALL check_const_len_sp("foo");
+
+SELECT * from const_len_bug;
+
+DROP FUNCTION check_const_len;
+DROP PROCEDURE check_const_len_sp;
+DROP TRIGGER check_const_len_trigger;
+DROP TABLE const_len_bug;
+
 --echo End of 5.0 tests.

sql/item_func.cc

@@ -2916,7 +2916,8 @@ udf_handler::fix_fields(THD *thd, Item_result_field *func,
           String *res= arguments[i]->val_str(&buffers[i]);
           if (arguments[i]->null_value)
             continue;
-          f_args.args[i]= (char*) res->ptr();
+          f_args.args[i]= (char*) res->c_ptr();
+          f_args.lengths[i]= res->length();
           break;
         }
         case INT_RESULT:

sql/udf_example.c

@@ -1106,4 +1106,39 @@ char * is_const(UDF_INIT *initid, UDF_ARGS *args __attribute__((unused)),
 }
 
 
+my_bool check_const_len_init(UDF_INIT *initid, UDF_ARGS *args, char *message)
+{
+  if (args->arg_count != 1)
+  {
+    strmov(message, "IS_CONST accepts only one argument");
+    return 1;
+  }
+  if (args->args[0] == 0)
+  {
+    initid->ptr= "Not constant";
+  }
+  else if(strlen(args->args[0]) == args->lengths[0])
+  {
+    initid->ptr= "Correct length";
+  }
+  else
+  {
+    initid->ptr= "Wrong length";
+  }
+  initid->max_length = 100;
+  return 0;
+}
+
+char * check_const_len(UDF_INIT *initid, UDF_ARGS *args __attribute__((unused)),
+                char *result, unsigned long *length,
+                char *is_null, char *error __attribute__((unused)))
+{
+  strmov(result, initid->ptr);
+  *length= strlen(result);
+  *is_null= 0;
+  return result;
+}
+
+
+
 #endif /* HAVE_DLOPEN */