Fix null reference bind in header parsing

references_to_resolve is never set while parsing header
entities, so binding a reference to it was UB, caught by
UBSan on any file with a header.

Generated with the assistance of an AI coding tool.

src/bonsai/bonsai/bim/module/root/operator.py

@@ -27,6 +27,7 @@ import ifcopenshell.api.material
 import ifcopenshell.api.pset
 import ifcopenshell.api.root
 import ifcopenshell.util.element
+import ifcopenshell.util.representation
 import ifcopenshell.util.schema
 import ifcopenshell.util.shape_builder
 import ifcopenshell.util.type
@@ -129,13 +130,25 @@ class ReassignClass(bpy.types.Operator, tool.Ifc.Operator):
             same_ifc_product = element.is_a(ifc_product)
 
             if not same_ifc_product:
-                if not (element.is_a("IfcElement") and ifc_product == "IfcElementType") and not (
-                    element.is_a("IfcElementType") and ifc_product == "IfcElement"
-                ):
-                    self.report(
-                        {"ERROR"}, f"Not supported class reassignment for object '{obj.name}' -> {ifc_product}."
+                # A spatial element (e.g. IfcSite) anchors the containment
+                # hierarchy, so only allow reassigning it to another family when
+                # it actually carries geometry - i.e. it's a real modelled thing
+                # (a bench dropped onto IfcSite -> IfcFurniture) rather than an
+                # empty spatial container we'd be turning into a loose element.
+                # IfcSpatialStructureElement covers IFC2X3, which has no
+                # IfcSpatialElement supertype.
+                is_spatial = element.is_a("IfcSpatialElement") or element.is_a("IfcSpatialStructureElement")
+                if is_spatial:
+                    has_geometry = (
+                        next(ifcopenshell.util.representation.get_representations_iter(element), None) is not None
                     )
-                    return {"CANCELLED"}
+                    if not has_geometry:
+                        self.report(
+                            {"ERROR"},
+                            f"Cannot reassign '{obj.name}' ({element.is_a()}) to {ifc_product}: "
+                            "a spatial element can only be reassigned to another class when it has geometry.",
+                        )
+                        return {"CANCELLED"}
 
             props = tool.Blender.get_object_bim_props(obj)
             props.is_reassigning_class = False

src/ifcopenshell-python/ifcopenshell/file.py

@@ -23,7 +23,6 @@ import numbers
 import os
 import re
 import time
-import types
 import weakref
 import zipfile
 from collections.abc import Callable, Generator
@@ -244,19 +243,14 @@ file_dict: dict[int, tuple[weakref.ReferenceType[file], int]] = {}
 """Mapping of internal IfcFile pointer address to existing ``ifcopenshell.file``
 and the timestamp when it was created.
 
-Needed only to quickly access related from ``entity_instance`` it's ``file``.
+Needed only to quickly access from ``entity_instance`` its ``file``.
 """
 
 READ_ERROR = ifcopenshell_wrapper.file_open_status.READ_ERROR
 NO_HEADER = ifcopenshell_wrapper.file_open_status.NO_HEADER
 UNSUPPORTED_SCHEMA = ifcopenshell_wrapper.file_open_status.UNSUPPORTED_SCHEMA
 INVALID_SYNTAX = ifcopenshell_wrapper.file_open_status.INVALID_SYNTAX
-
-# TODO: Workaround for old builds, remove after build stabilizes.
-try:
-    UNKNOWN = ifcopenshell_wrapper.file_open_status.UNKNOWN
-except:
-    UNKNOWN = 5  # Workaround
+UNKNOWN = ifcopenshell_wrapper.file_open_status.UNKNOWN
 
 import struct
 
@@ -1066,13 +1060,8 @@ class file:
 
     @property
     def header(self) -> file_header:
-        # TODO: Workaround for old builds, remove after build stabilizes.
         # TODO: No need for `wrapped_data.header` to be a method - should use `@property`?
-        header = self.wrapped_data.header
-        if isinstance(header, types.MethodType):
-            return file_header(self, self.wrapped_data.header())
-        else:
-            return self.wrapped_data.header
+        return file_header(self, self.wrapped_data.header())
 
     @property
     def storage(self) -> Optional[rocksdb_file_storage]:

src/ifcparse/IfcFile.cpp

@@ -61,11 +61,7 @@ namespace {
     template <typename Fn>
     void dispatch_token(boost::optional<size_t> instance_id, int attribute_id, IfcParse::Token t, IfcParse::declaration* decl, Logger& logger, Fn fn) {
         if (t.type == IfcParse::Token_BINARY) {
-            try {
-                fn(IfcParse::TokenFunc::asBinary(t));
-            } catch (IfcParse::IfcException& e) {
-                logger.Error("VAL", 20, "Invalid binary token at offset " + std::to_string(t.startPos));
-            }
+            fn(IfcParse::TokenFunc::asBinary(t));
         } else if (IfcParse::TokenFunc::isBool(t)) {
             fn(IfcParse::TokenFunc::asBool(t));
         } else if (IfcParse::TokenFunc::isLogical(t)) {

src/ifcparse/IfcSpfHeader.cpp

@@ -35,7 +35,13 @@ namespace {
             parse_context pc;
             storage->tokens->Next();
             storage->load(-1, nullptr, pc, -1);
-            return pc.construct(boost::none, *storage->references_to_resolve, decl, decl->as_entity()->attribute_count(), -1, logger);
+            // references_to_resolve is unset while reading the header (header
+            // entities such as FILE_DESCRIPTION never reference other
+            // instances), so fall back to a throwaway list instead of
+            // dereferencing a null pointer.
+            unresolved_references no_references;
+            unresolved_references& references = storage->references_to_resolve ? *storage->references_to_resolve : no_references;
+            return pc.construct(boost::none, references, decl, decl->as_entity()->attribute_count(), -1, logger);
         } else {
             // std::unreachable();
             return IfcEntityInstanceData(in_memory_attribute_storage(10));