Add support for real-time updating of union values

fox-it · Oct 29, 2023 · 961fc80 · 961fc80
1 parent 82df7ca
commit 961fc80
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Showing 7 changed files with 273 additions and 66 deletions.
diff --git a/dissect/cstruct/compiler.py b/dissect/cstruct/compiler.py
@@ -66,7 +66,7 @@ def compile(self, structure: type[Structure]) -> type[Structure]:
             return structure
 
         try:
-            structure._read = self.compile_read(structure.fields, structure.__name__, structure.align)
+            structure._read = self.compile_read(structure.fields, structure.__name__, structure.__align__)
             structure.__compiled__ = True
         except Exception as e:
             # Silently ignore, we didn't compile unfortunately
@@ -218,19 +218,11 @@ def align_to_field(field: Field) -> Iterator[str]:
             yield f"stream.seek(-stream.tell() & (cls.alignment - 1), {io.SEEK_CUR})"
 
     def _generate_structure(self, field: Field) -> Iterator[str]:
-        if field.type.anonymous:
-            template = f"""
-            _s = stream.tell()
-            _v = {self._map_field(field)}._read(stream, context=r)
-            r.update(_v._values)
-            s.update(_v._sizes)
-            """
-        else:
-            template = f"""
-            _s = stream.tell()
-            r["{field.name}"] = {self._map_field(field)}._read(stream, context=r)
-            s["{field.name}"] = stream.tell() - _s
-            """
+        template = f"""
+        _s = stream.tell()
+        r["{field.name}"] = {self._map_field(field)}._read(stream, context=r)
+        s["{field.name}"] = stream.tell() - _s
+        """
 
         yield dedent(template)
 

diff --git a/dissect/cstruct/cstruct.py b/dissect/cstruct/cstruct.py
@@ -189,7 +189,7 @@ def __getattr__(self, attr: str) -> Any:
         raise AttributeError(f"Invalid attribute: {attr}")
 
     def _next_anonymous(self) -> str:
-        name = f"anonymous_{self._anonymous_count}"
+        name = f"__anonymous_{self._anonymous_count}__"
         self._anonymous_count += 1
         return name
 
@@ -364,8 +364,8 @@ def _make_struct(
             None,
             attrs={
                 "fields": fields,
-                "align": align,
-                "anonymous": anonymous,
+                "__align__": align,
+                "__anonymous__": anonymous,
             },
         )
 

diff --git a/dissect/cstruct/types/enum.py b/dissect/cstruct/types/enum.py
@@ -15,13 +15,16 @@ class EnumMetaType(EnumMeta, MetaType):
 
     def __call__(
         cls,
-        value: Union[cstruct, int, BinaryIO, bytes],
+        value: Union[cstruct, int, BinaryIO, bytes] = None,
         name: Optional[str] = None,
         type_: Optional[MetaType] = None,
         *args,
         **kwargs,
     ):
         if name is None:
+            if value is None:
+                value = cls.type()
+
             if not isinstance(value, int):
                 # value is a parsable value
                 value = cls.type(value)