Adds bu_list_t members for unsigned SEIs (#432)

Author: bjornvolcker

lib/src/sv_bu_list.c

@@ -96,6 +96,8 @@ bu_list_item_create(const bu_info_t *bu)
   item->bu = (bu_info_t *)bu;
   item->validation_status = get_validation_status_from_bu(bu);
   item->tmp_validation_status = item->validation_status;
+  item->validation_status_if_sei_ok = ' ';
+  item->verified_signature = -1;
 
   return item;
 }

lib/src/sv_internal.h

@@ -179,9 +179,14 @@ struct _bu_list_item_t {
   bool has_been_decoded;  // Marks a SEI as decoded. Decoding it twice might overwrite
   // vital information.
   bool used_in_gop_hash;  // Marks the BU as being part of a computed |gop_hash|.
-
   bool used_for_linked_hash;
 
+  // Members used when there are unsigned SEIs involved. The content of a SEI can only be
+  // trusted once the signed SEI has been verified.
+  char validation_status_if_sei_ok;
+  const bu_list_item_t *associated_sei;  // Which SEI this item is associated with.
+  int verified_signature;
+
   // Members used when synchronizing the first usable SEI with the I-frame(s).
   bool in_validation;  // Marks the SEI that is currently up for use.
   char tmp_validation_status;  // Temporary status used before updating the final one.