Fixed cancelled ReadAsync/WriteAsync throwing the exception of the native operation instead of an OperationCanceledException

src/Magick.NET/Helpers/AsyncStreamWrapper.cs

@@ -59,7 +59,18 @@ public async Task ReadAsync(Action action, CancellationToken cancellationToken)
             TaskScheduler.Default);
         var readTask = ReadAsync(cancellationToken);
 
-        await Task.WhenAll(actionTask, readTask).ConfigureAwait(false);
+        try
+        {
+            await Task.WhenAll(actionTask, readTask).ConfigureAwait(false);
+        }
+        catch when (_exceptionThrown)
+        {
+            // The native operation failed because a stream operation failed. When that failure was
+            // caused by a cancellation the exception of the native operation (e.g. a corrupt image
+            // exception from the coder) should be replaced with an OperationCanceledException.
+            cancellationToken.ThrowIfCancellationRequested();
+            throw;
+        }
 
         if (_exceptionThrown)
             cancellationToken.ThrowIfCancellationRequested();
@@ -88,7 +99,19 @@ public async Task WriteAsync(Action action, CancellationToken cancellationToken)
         var readTask = ReadAsync(cancellationToken);
         var writeTask = WriteAsync(cancellationToken);
 
-        await Task.WhenAll(actionTask, readTask, writeTask).ConfigureAwait(false);
+        try
+        {
+            await Task.WhenAll(actionTask, readTask, writeTask).ConfigureAwait(false);
+        }
+        catch when (_exceptionThrown)
+        {
+            // The native operation failed because a stream operation failed. When that failure was
+            // caused by a cancellation the exception of the native operation (e.g. "Output file
+            // write error --- out of disk space?" from the jpeg coder) should be replaced with
+            // an OperationCanceledException.
+            cancellationToken.ThrowIfCancellationRequested();
+            throw;
+        }
 
         if (_exceptionThrown)
             cancellationToken.ThrowIfCancellationRequested();

tests/Magick.NET.Tests/Helpers/AsyncStreamWrapperTest/TheReadAsyncMethod.cs

@@ -116,5 +116,28 @@ unsafe void ReadSync()
 
             await Assert.ThrowsAsync<OperationCanceledException>(() => wrapper.ReadAsync(ReadSync, cancellationTokenSource.Token));
         }
+
+        [Fact]
+        public async Task ShouldThrowExceptionWhenOperationIsCancelledAndActionThrowsException()
+        {
+            using var stream = new MemoryStream();
+            using var wrapper = AsyncStreamWrapper.CreateForReading(stream);
+
+            using var cancellationTokenSource = new CancellationTokenSource();
+            cancellationTokenSource.Cancel();
+
+            unsafe void ReadSync()
+            {
+                var buffer = new byte[10];
+                fixed (byte* p = buffer)
+                {
+                    var count = wrapper.Read((IntPtr)p, (UIntPtr)10, IntPtr.Zero);
+                    if (count == -1)
+                        throw new InvalidOperationException("Simulates the exception the native code throws when a read fails (e.g. a corrupt image exception).");
+                }
+            }
+
+            await Assert.ThrowsAsync<OperationCanceledException>(() => wrapper.ReadAsync(ReadSync, cancellationTokenSource.Token));
+        }
     }
 }

tests/Magick.NET.Tests/Helpers/AsyncStreamWrapperTest/TheWriteAsyncMethod.cs

@@ -113,5 +113,28 @@ unsafe void WriteSync()
 
             await Assert.ThrowsAsync<OperationCanceledException>(() => wrapper.WriteAsync(WriteSync, cancellationTokenSource.Token));
         }
+
+        [Fact]
+        public async Task ShouldThrowExceptionWhenOperationIsCancelledAndActionThrowsException()
+        {
+            using var stream = new MemoryStream();
+            using var wrapper = AsyncStreamWrapper.CreateForWriting(stream);
+
+            using var cancellationTokenSource = new CancellationTokenSource();
+            cancellationTokenSource.Cancel();
+
+            unsafe void WriteSync()
+            {
+                var buffer = new byte[5];
+                fixed (byte* p = buffer)
+                {
+                    var count = wrapper.Write((IntPtr)p, (UIntPtr)5, IntPtr.Zero);
+                    if (count == -1)
+                        throw new InvalidOperationException("Simulates the exception the native code throws when a write fails (e.g. the jpeg coder).");
+                }
+            }
+
+            await Assert.ThrowsAsync<OperationCanceledException>(() => wrapper.WriteAsync(WriteSync, cancellationTokenSource.Token));
+        }
     }
 }

tests/Magick.NET.Tests/MagickImageTests/TheReadAsyncMethod.cs

@@ -4,6 +4,7 @@
 using System;
 using System.IO;
 using System.Text;
+using System.Threading;
 using System.Threading.Tasks;
 using ImageMagick;
 using Xunit;
@@ -198,6 +199,17 @@ public async Task ShouldThrowExceptionWhenStreamIsNull()
                 await Assert.ThrowsAsync<ArgumentNullException>("stream", () => image.ReadAsync((Stream)null!, TestContext.Current.CancellationToken));
             }
 
+            [Fact]
+            public async Task ShouldThrowOperationCanceledExceptionWhenOperationIsCancelled()
+            {
+                using var image = new MagickImage();
+                using var stream = File.OpenRead(Files.ImageMagickJPG);
+                using var cancellationTokenSource = new CancellationTokenSource();
+                cancellationTokenSource.Cancel();
+
+                await Assert.ThrowsAsync<OperationCanceledException>(() => image.ReadAsync(stream, cancellationTokenSource.Token));
+            }
+
             [Fact]
             public async Task ShouldThrowExceptionWhenStreamIsEmpty()
             {

tests/Magick.NET.Tests/MagickImageTests/TheWriteAsyncMethod.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.IO;
+using System.Threading;
 using System.Threading.Tasks;
 using ImageMagick;
 using ImageMagick.Formats;
@@ -225,6 +226,19 @@ public async Task ShouldThrowExceptionWhenStreamIsNull()
 
                 await Assert.ThrowsAsync<ArgumentNullException>("stream", () => image.WriteAsync((Stream)null!, TestContext.Current.CancellationToken));
             }
+
+            [Fact]
+            public async Task ShouldThrowOperationCanceledExceptionWhenOperationIsCancelled()
+            {
+                using var image = new MagickImage(MagickColors.Red, 100, 100);
+                image.Format = MagickFormat.Jpeg;
+
+                using var stream = new MemoryStream();
+                using var cancellationTokenSource = new CancellationTokenSource();
+                cancellationTokenSource.Cancel();
+
+                await Assert.ThrowsAsync<OperationCanceledException>(() => image.WriteAsync(stream, cancellationTokenSource.Token));
+            }
         }
 
         public class WithStreamAndMagickFormat