HandyOrg/HandyControl · error · ArgumentNullException

ArgumentNullException

Error message

ArgumentNullException

What it means

ComStreamFromDataStream wraps a managed System.IO.Stream so it can be exposed as a COM IStream. Its constructor requires a non-null stream and throws ArgumentNullException(name: "dataStream") when null is passed. This guards the internal COM interop adapter from later NullReferenceExceptions.

Solutions

1. Ensure the Stream passed in is non-null: check the result of File.Open/GetManifestResourceStream/Assembly.GetStream before constructing.
2. If the stream may legitimately be missing, throw or report a file-not-found error at the source instead of forwarding null.
3. Catch ArgumentNullException at the interop boundary and map it to a meaningful 'data stream unavailable' error.

Example fix

// before
var comStream = new ComStreamFromDataStream(GetResourceStream(name)); // null if missing

// after
var stream = GetResourceStream(name);
if (stream == null) throw new FileNotFoundException($"Resource '{name}' not found.");
var comStream = new ComStreamFromDataStream(stream);

if (stream == null) throw new FileNotFoundException("Data stream is required but was not found.");

static bool HasStream(Stream s) => s != null;

try { comStream = new ComStreamFromDataStream(stream); }
catch (ArgumentNullException) { comStream = null; ReportMissingStream(); }

When it happens

Trigger: Constructing ComStreamFromDataStream with a null Stream reference — typically when a factory returned null (e.g. File.Open failed upstream and null was passed on) and the result is fed into the COM stream adapter.

Common situations: Clipboard/OLE drag-drop interop code that streams data, resource loading where a stream lookup (GetManifestResourceStream) returned null and was forwarded unchecked.

Related errors

• Wrote an incorrect number of bytes
• Wrote an incorrect number of bytes
• stream null
• NotImplemented
• NotSupportedException

AI-assisted analysis of HandyOrg/HandyControl@2c0875ebd6 (2026-09-14). Data as JSON: /api/errors/495b9e4682b619e3. Report an issue: GitHub.

Appendix: source

Thrown at src/Shared/HandyControl_Shared/Tools/Interop/InteropValues.cs:838

        public int Flags;
        public int Version;
        public int SigCount;
        public int SigSize;

        public IntPtr SigPattern = IntPtr.Zero;
        public IntPtr SigMask = IntPtr.Zero;
    }

    internal class ComStreamFromDataStream : IStream
    {
        protected Stream DataStream;

        // to support seeking ahead of the stream length...
        private long _virtualPosition = -1;

        internal ComStreamFromDataStream(Stream dataStream)
        {
            this.DataStream = dataStream ?? throw new ArgumentNullException(nameof(dataStream));
        }

        private void ActualizeVirtualPosition()
        {
            if (_virtualPosition == -1) return;

            if (_virtualPosition > DataStream.Length)
                DataStream.SetLength(_virtualPosition);

            DataStream.Position = _virtualPosition;

            _virtualPosition = -1;
        }

        public virtual IStream Clone()
        {
            NotImplemented();
            return null;

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