fixed bug saving files with history entries which contain attachments.

bin/kdbx.dart

@@ -27,7 +27,6 @@ void main(List<String> arguments) {
     }
     print(error);
     exit(64);
-    return null;
   });
 
   //  final inputFile = args['input'] as String;

lib/src/kdbx_entry.dart

@@ -85,6 +85,16 @@ class KdbxEntry extends KdbxObject {
 
   final List<KdbxEntry> history;
 
+  @override
+  set file(KdbxFile file) {
+    super.file = file;
+    // TODO this looks like some weird workaround, get rid of the
+    // `file` reference.
+    for (final historyEntry in history) {
+      historyEntry.file = file;
+    }
+  }
+
   XmlElement get _historyElement => node
           .findElements(KdbxXml.NODE_HISTORY)
           .singleWhere((_) => true, orElse: () {
@@ -132,7 +142,7 @@ class KdbxEntry extends KdbxObject {
       if (binary.isInline) {
         binary.saveToXml(value);
       } else {
-        final binaryIndex = file.ctx.findBinaryId(binary);
+        final binaryIndex = ctx.findBinaryId(binary);
         value.addAttribute(KdbxXml.ATTR_REF, binaryIndex.toString());
       }
       return XmlElement(XmlName(KdbxXml.NODE_BINARY))

lib/src/kdbx_object.dart

@@ -75,22 +75,26 @@ abstract class KdbxNode with Changeable<KdbxNode> {
 }
 
 abstract class KdbxObject extends KdbxNode {
-  KdbxObject.create(
+  KdbxObject.create(this.ctx, this.file, String nodeName, KdbxGroup parent)
-      KdbxReadWriteContext ctx, this.file, String nodeName, KdbxGroup parent)
+      : assert(ctx != null),
-      : times = KdbxTimes.create(ctx),
+        times = KdbxTimes.create(ctx),
         _parent = parent,
         super.create(nodeName) {
     _uuid.set(KdbxUuid.random());
   }
 
-  KdbxObject.read(KdbxReadWriteContext ctx, KdbxGroup parent, XmlElement node)
+  KdbxObject.read(this.ctx, KdbxGroup parent, XmlElement node)
-      : times = KdbxTimes.read(node.findElements('Times').single, ctx),
+      : assert(ctx != null),
+        times = KdbxTimes.read(node.findElements('Times').single, ctx),
         _parent = parent,
         super.read(node);
 
   /// the file this object is part of. will be set AFTER loading, etc.
+  /// TODO: We should probably get rid of this `file` reference.
   KdbxFile file;
 
+  final KdbxReadWriteContext ctx;
+
   final KdbxTimes times;
 
   KdbxUuid get uuid => _uuid.get();

test/kdbx4_test.dart

@@ -1,6 +1,5 @@
 import 'dart:io';
 
-import 'package:argon2_ffi_base/argon2_ffi_base.dart';
 import 'package:kdbx/kdbx.dart';
 import 'package:kdbx/src/kdbx_header.dart';
 import 'package:logging/logging.dart';