BitmapDecoder.Create does not handle FileStream with FileOptions.Asynchronous

[vonzshik]

• .NET Core Version: (e.g. 3.0 Preview1, or daily build number, use dotnet --info)
  5.0.201
• Windows version: (winver)
  19042.867
• Does the bug reproduce also in WPF for .NET Framework 4.8?: Yes/No
  Yes.

Problem description:

BitmapDecoder.Create throws ArgumentException ("Value does not fall within the expected range.") whenever the stream argument is FileStream with FileOptions.Asynchronous.

Actual behavior:

at System.Windows.Media.Imaging.BitmapDecoder.SetupDecoderFromUriOrStream(Uri uri, Stream stream, BitmapCacheOption cacheOption, Guid& clsId, Boolean& isOriginalWritable, Stream& uriStream, UnmanagedMemoryStream& unmanagedMemoryStream, SafeFileHandle& safeFilehandle)
  at System.Windows.Media.Imaging.BitmapDecoder.CreateFromUriOrStream(Uri baseUri, Uri uri, Stream stream, BitmapCreateOptions createOptions, BitmapCacheOption cacheOption, RequestCachePolicy uriCachePolicy, Boolean insertInDecoderCache)
  at System.Windows.Media.Imaging.BitmapDecoder.Create(Stream bitmapStream, BitmapCreateOptions createOptions, BitmapCacheOption cacheOption)

Expected behavior:

BitmapDecoder.Create shouldn't throw an exception.

Minimal repro:

using var fs = new FileStream("image.jpg",
	FileMode.Open,
	FileAccess.Read,
	FileShare.Read,
	4096,
	FileOptions.Asynchronous);

var decoder = BitmapDecoder.Create(fs, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.None);

[lindexi]

The BitmapDecoder.Create will call the IWICImagingFactory_CreateDecoderFromFileHandle_Proxy which in WIC to create the decoder. But the IWICImagingFactory_CreateDecoderFromFileHandle_Proxy can not receive the Asynchronous SafeFilehandle.

IWICImagingFactory_CreateDecoderFromFileHandle_Proxy function - Win32 apps | Microsoft Docs

[vonzshik]

@lindexi thank you for taking a look. I assume there is no API for an async SafeFileHandle, yes?

The fact that I was able to get around this issue by making a proxy stream, which wraps the original FileStream (and the API you've mentioned does confirm my suspicions), makes me think that BitmapDecoder.Create does check whether a provided stream is indeed a FileStream, in which case it uses a different set of API (I guess as a sort of optimization?), unlike for other cases.

If so, maybe it's a good idea to disable this behavior whenever FileStream.IsAsync is true? Otherwise, I think making the exception more verbose will surely help solving this problem for other users.

[lindexi]

@vonzshik I agree with you.

[lindexi]

I write a demo to show the IWICImagingFactory_CreateDecoderFromFileHandle_Proxy do not support the Asynchronous file stream.

    class Program
    {
        static void Main(string[] args)
        {
            CheckHResult(UnsafeNativeMethods.WICCodec.CreateImagingFactory(UnsafeNativeMethods.WICCodec.WINCODEC_SDK_VERSION,
                out var pImagingFactory));

            using var fs = new FileStream("image.jpg",
                FileMode.Open,
                FileAccess.Read,
                FileShare.Read,
                4096,
                FileOptions.Asynchronous);

            Guid vendorMicrosoft = new Guid(MILGuidData.GUID_VendorMicrosoft);
            UInt32 metadataFlags = (uint)WICMetadataCacheOptions.WICMetadataCacheOnDemand;

            CheckHResult
            (
                UnsafeNativeMethods.WICImagingFactory.CreateDecoderFromFileHandle
                (
                    pImagingFactory,
                    fs.SafeFileHandle,
                    ref vendorMicrosoft,
                    metadataFlags,
                    out var decoder
                )
            );
        }

        static void CheckHResult(int hr)
        {
            if (hr < 0)
            {
                Exception exceptionForHR = Marshal.GetExceptionForHR(hr, (IntPtr)(-1));

                throw exceptionForHR;
            }
        }
    }

See https://github.com/lindexi/lindexi_gd/tree/78c73fe25229f0b50992102e59c01cd535e60c31/JemlemlacuLemjakarbabo

[lindexi]

I write a Chinese blog about this, see https://translate.google.com/translate?sl=zh-CN&tl=en&u=https://blog.lindexi.com/post/WPF-%25E5%25B7%25B2%25E7%259F%25A5%25E9%2597%25AE%25E9%25A2%2598-BitmapDecoder.Create-%25E4%25B8%258D%25E6%2594%25AF%25E6%258C%2581%25E4%25BC%25A0%25E5%2585%25A5-Asynchronous-%25E7%259A%2584%25E6%2596%2587%25E4%25BB%25B6%25E6%25B5%2581.html