ReadFile and WriteFile do not match with .NET overlapped structure

[raffaeler]

Actual behavior

The signature generated for the ReadFile and WriteFile structures is:

internal static unsafe winmdroot.Foundation.BOOL WriteFile(SafeHandle hFile, void* lpBuffer,
    uint nNumberOfBytesToWrite, uint* lpNumberOfBytesWritten,
    winmdroot.System.IO.OVERLAPPED* lpOverlapped) {}

On the other hand, .NET already defines System.Threading.NativeOverlapped which must be used with ThreadPoolBoundHandle.GetNativeOverlappedState and other APIs.

As a consequence, when using the asynchronous behaviour on Windows, I can't rely on the generated code, but I have to define separately the PInvokes.

Please note that this is also true for other APIs like:

• GetOverlappedResult
• ClearCommError
• WaitCommEvent
• WIN32_ERROR (must be casted to match Marshal.GetLastWin32Error()

Expected behavior

Whenever .NET defines some interop code, I expect the generated code matches them. Or at least provides a different overload with a native pointer so that it can be used with code different than the one created by the genrator.
In general, when there is a pointer, it would be useful to get overloads with a "void*" to avoid being blocked.

Repro steps

1. NativeMethods.txt content:

CreateFile
ReadFile
WriteFile
GetOverlappedResult
CloseHandle

2. NativeMethods.json content (if present):

N/A

3. Any of your own code that should be shared?

Not needed

Context

• CsWin32 version: <PackageReference Include="Microsoft.Windows.CsWin32" Version="0.1.647-beta">
• Win32Metadata version: N/A
• Target Framework: net6.0
• LangVersion : N/A

[AArnott]

Interoperating with existing .NET APIs is certainly desirable. Let's see what we can do here.

[AArnott]

Thank you for the feedback. We'll get the Overlapped struct issue fixed. For the other APIs, please open individual issues if there are more .NET structs that we should use instead of generating our own.
As for the WIN32_ERROR cast, that's by design. Sadly, C# doesn't allow us to express structs with implicit conversion operators.

[raffaeler]

@AArnott From what I see the fix is valid for any Win32 function using the Overlapped structure, right?
In other words, this include also the fix for ReadFileEx and WriteFileEx and other APIs, right?

BTW what is the trigger that updates the nuget package? When should I expect to see it?

Thank you!

[AArnott]

Yes, the fix will replace all uses of Overlapped, altering all the APIs that reference it.

I expect to release another CsWin32 to nuget.org by Thursday of this week. In the meantime you can consume our nightly builds with these instructions.