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.

2 files changed, 37 insertions, 1 deletions

diff --git a/sql/item_func.cc b/sql/item_func.cc
index 9a26169ad30..4492b7519aa 100644
--- a/sql/item_func.cc
+++ b/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:
diff --git a/sql/udf_example.c b/sql/udf_example.c
index b603464568e..5165a577555 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, "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 */