Merge pull request #512 from bazsi/filterx-handle-unsigned-length-value-in-stack-allocated-strings

Filterx stack based string allocation fixes

Author: MrAnno

lib/filterx/func-set-fields.c

@@ -358,7 +358,7 @@ _extract_field_key_obj(FilterXExpr *key, GError **error)
 static gboolean
 _are_field_keys_equal(FilterXObject *key_a, FilterXObject *key_b)
 {
-  gsize len_a, len_b;
+  gsize len_a = 0, len_b = 0;
   const gchar *key_a_str = filterx_string_get_value_ref(key_a, &len_a);
   const gchar *key_b_str = filterx_string_get_value_ref(key_b, &len_b);
 

lib/filterx/func-vars.c

@@ -146,7 +146,7 @@ _load_from_dict(FilterXObject *key, FilterXObject *value, gpointer user_data)
       return FALSE;
     }
 
-  gsize key_len;
+  gsize key_len = 0;
   const gchar *key_str = filterx_string_get_value_ref(key, &key_len);
   APPEND_ZERO(key_str, key_str, key_len);
 

lib/filterx/object-string.c

@@ -132,7 +132,7 @@ _string_clone(FilterXObject *s)
 static inline FilterXString *
 _string_new(const gchar *str, gssize str_len, FilterXStringTranslateFunc translate)
 {
-  if (str_len < 0)
+  if (str_len == -1)
     str_len = strlen(str);
 
   FilterXString *self = g_malloc(sizeof(FilterXString) + str_len + 1);

lib/filterx/object-string.h

@@ -53,7 +53,11 @@ FilterXObject *filterx_string_new_translated(const gchar *str, gssize str_len, F
 FilterXObject *filterx_bytes_new(const gchar *str, gssize str_len);
 FilterXObject *filterx_protobuf_new(const gchar *str, gssize str_len);
 
-/* NOTE: Consider using filterx_object_extract_string_ref() to also support message_value. */
+/* NOTE: Consider using filterx_object_extract_string_ref() to also support message_value.
+ *
+ * Also NOTE: the returned string may not be NUL terminated, although often
+ * it will be. Generic code should handle the cases where it is not.
+ */
 static inline const gchar *
 filterx_string_get_value_ref(FilterXObject *s, gsize *length)
 {
@@ -64,6 +68,8 @@ filterx_string_get_value_ref(FilterXObject *s, gsize *length)
 
   if (length)
     *length = self->str_len;
+  else
+    g_assert(self->str[self->str_len] == 0);
   return self->str;
 }
 
@@ -89,7 +95,7 @@ void filterx_string_global_deinit(void);
   { \
     FILTERX_OBJECT_STACK_INIT(string), \
     .str = (cstr), \
-    .str_len = ((cstr_len) < 0 ? strlen(cstr) : (cstr_len)), \
+    .str_len = (((gssize) cstr_len) == -1 ? strlen(cstr) : (cstr_len)), \
   }
 
 #define FILTERX_STRING_DECLARE_ON_STACK(_name, cstr, cstr_len) \