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 too.


mysql-test/r/udf.result:
  Test case to check constants passed UDFs.
mysql-test/t/udf.test:
  Test case to check constants passed UDFs.
sql/item_func.cc:
  UDF _init functions are now passed the length of the constants, rather than the max
  length of the var containing the constant.
sql/udf_example.c:
  Added check_const_len functions. The check_const_len_init functions checks that the
  lengths of constants are correctly passed.
sql/udf_example.def:
  Add new example functions to windows dll export list.

3 files changed, 39 insertions, 1 deletions

diff --git a/sql/item_func.cc b/sql/item_func.cc
index c70cfa1ce2a..21579763635 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -2924,7 +2924,8 @@ 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:
diff --git a/sql/udf_example.c b/sql/udf_example.c
index 0f28c2a14b0..df3a69755ad 100644
--- a/sql/udf_example.c
+++ b/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, "CHECK_CONST_LEN accepts only one argument");
+    return 1;
+  }
+  if (args->args[0] == 0)
+  {
+    initid->ptr= (char*)"Not constant";
+  }
+  else if(strlen(args->args[0]) == args->lengths[0])
+  {
+    initid->ptr= (char*)"Correct length";
+  }
+  else
+  {
+    initid->ptr= (char*)"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 */
diff --git a/sql/udf_example.def b/sql/udf_example.def
index 7a87147d7b6..3d569941cc8 100644
--- a/sql/udf_example.def
+++ b/sql/udf_example.def
@@ -23,3 +23,5 @@ EXPORTS
   avgcost
   is_const
   is_const_init
+  check_const_len
+  check_const_len_init