fix: support arbitrary width integers (fixes: pdfminer#886)

pdfminer/utils.py

@@ -359,22 +359,12 @@ def choplist(n: int, seq: Iterable[_T]) -> Iterator[Tuple[_T, ...]]:
 
 
 def nunpack(s: bytes, default: int = 0) -> int:
-    """Unpacks 1 to 4 or 8 byte integers (big endian)."""
+    """Unpacks variable-length integers (big endian)."""
     length = len(s)
     if not length:
         return default
-    elif length == 1:
-        return ord(s)
-    elif length == 2:
-        return cast(int, struct.unpack(">H", s)[0])
-    elif length == 3:
-        return cast(int, struct.unpack(">L", b"\x00" + s)[0])
-    elif length == 4:
-        return cast(int, struct.unpack(">L", s)[0])
-    elif length == 8:
-        return cast(int, struct.unpack(">Q", s)[0])
     else:
-        raise PDFTypeError("invalid length: %d" % length)
+        return int.from_bytes(s, "big")
 
 
 PDFDocEncoding = "".join(