Refactor the way terminal handles are managed so the native library fully abstracts them.

Author: alexrp

src/core/Native/TerminalInterop.cs

@@ -2,6 +2,11 @@ namespace Vezel.Cathode.Native;
 
 internal static unsafe partial class TerminalInterop
 {
+    [StructLayout(LayoutKind.Sequential)]
+    public struct TerminalDescriptor
+    {
+    }
+
     public enum TerminalException
     {
         None,
@@ -98,19 +103,24 @@ bool TryLoad(out nint handle, params string[] paths)
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
     public static partial void Initialize();
 
-    [LibraryImport(Library, EntryPoint = "cathode_get_handles")]
+    [LibraryImport(Library, EntryPoint = "cathode_get_descriptors")]
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
-    public static partial void GetHandles(nuint* stdIn, nuint* stdOut, nuint* stdErr, nuint* ttyIn, nuint* ttyOut);
+    public static partial void GetDescriptors(
+        TerminalDescriptor** stdIn,
+        TerminalDescriptor** stdOut,
+        TerminalDescriptor** stdErr,
+        TerminalDescriptor** ttyIn,
+        TerminalDescriptor** ttyOut);
 
     [LibraryImport(Library, EntryPoint = "cathode_is_valid")]
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
     [return: MarshalAs(UnmanagedType.U1)]
-    public static partial bool IsValid(nuint handle, [MarshalAs(UnmanagedType.U1)] bool write);
+    public static partial bool IsValid(TerminalDescriptor* descriptor, [MarshalAs(UnmanagedType.U1)] bool write);
 
     [LibraryImport(Library, EntryPoint = "cathode_is_interactive")]
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
     [return: MarshalAs(UnmanagedType.U1)]
-    public static partial bool IsInteractive(nuint handle);
+    public static partial bool IsInteractive(TerminalDescriptor* descriptor);
 
     [LibraryImport(Library, EntryPoint = "cathode_query_size")]
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
@@ -133,13 +143,13 @@ public static partial TerminalResult SetMode(
 
     [LibraryImport(Library, EntryPoint = "cathode_read")]
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
-    public static partial TerminalResult Read(nuint handle, byte* buffer, int length, int* progress);
+    public static partial TerminalResult Read(TerminalDescriptor* descriptor, byte* buffer, int length, int* progress);
 
     [LibraryImport(Library, EntryPoint = "cathode_write")]
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
-    public static partial TerminalResult Write(nuint handle, byte* buffer, int length, int* progress);
+    public static partial TerminalResult Write(TerminalDescriptor* descriptor, byte* buffer, int length, int* progress);
 
     [LibraryImport(Library, EntryPoint = "cathode_poll")]
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
-    public static partial void Poll([MarshalAs(UnmanagedType.U1)] bool write, nuint* handles, bool* results, int count);
+    public static partial void Poll([MarshalAs(UnmanagedType.U1)] bool write, int* fds, bool* results, int count);
 }

src/core/Terminals/NativeTerminalReader.cs

@@ -2,47 +2,47 @@
 
 namespace Vezel.Cathode.Terminals;
 
-internal sealed class NativeTerminalReader : TerminalReader
+internal sealed unsafe class NativeTerminalReader : TerminalReader
 {
     // Note that the buffer size used affects how many characters the Windows console host will allow the user to type
     // in a single line (in cooked mode).
     private const int ReadBufferSize = 4096;
 
     public NativeVirtualTerminal Terminal { get; }
 
-    public nuint Handle { get; }
+    public TerminalInterop.TerminalDescriptor* Descriptor { get; }
 
-    public override sealed Stream Stream { get; }
+    public override Stream Stream { get; }
 
-    public override sealed TextReader TextReader { get; }
+    public override TextReader TextReader { get; }
 
-    public override sealed bool IsValid { get; }
+    public override bool IsValid { get; }
 
-    public override sealed bool IsInteractive { get; }
+    public override bool IsInteractive { get; }
 
     private readonly SemaphoreSlim _semaphore;
 
     private readonly Action<nuint, CancellationToken>? _cancellationHook;
 
     public NativeTerminalReader(
         NativeVirtualTerminal terminal,
-        nuint handle,
+        TerminalInterop.TerminalDescriptor* descriptor,
         SemaphoreSlim semaphore,
         Action<nuint, CancellationToken>? cancellationHook)
     {
         Terminal = terminal;
-        Handle = handle;
+        Descriptor = descriptor;
         _semaphore = semaphore;
         _cancellationHook = cancellationHook;
         Stream = new SynchronizedStream(new TerminalInputStream(this));
         TextReader =
             new SynchronizedTextReader(
                 new StreamReader(Stream, Cathode.Terminal.Encoding, false, ReadBufferSize, true));
-        IsValid = TerminalInterop.IsValid(handle, write: false);
-        IsInteractive = TerminalInterop.IsInteractive(handle);
+        IsValid = TerminalInterop.IsValid(descriptor, write: false);
+        IsInteractive = TerminalInterop.IsInteractive(descriptor);
     }
 
-    private unsafe int ReadPartialNative(scoped Span<byte> buffer, CancellationToken cancellationToken)
+    private int ReadPartialNative(scoped Span<byte> buffer, CancellationToken cancellationToken)
     {
         using var guard = Terminal.Control.Guard();
 
@@ -53,12 +53,12 @@ private unsafe int ReadPartialNative(scoped Span<byte> buffer, CancellationToken
 
         using (_semaphore.Enter(cancellationToken))
         {
-            _cancellationHook?.Invoke(Handle, cancellationToken);
+            _cancellationHook?.Invoke((nuint)Descriptor, cancellationToken);
 
             int progress;
 
             fixed (byte* p = buffer)
-                TerminalInterop.Read(Handle, p, buffer.Length, &progress).ThrowIfError();
+                TerminalInterop.Read(Descriptor, p, buffer.Length, &progress).ThrowIfError();
 
             return progress;
         }

src/core/Terminals/NativeTerminalWriter.cs

@@ -2,35 +2,35 @@
 
 namespace Vezel.Cathode.Terminals;
 
-internal sealed class NativeTerminalWriter : TerminalWriter
+internal sealed unsafe class NativeTerminalWriter : TerminalWriter
 {
     // Unlike NativeTerminalReader, the buffer size here is arbitrary and only has performance implications.
     private const int WriteBufferSize = 256;
 
     public NativeVirtualTerminal Terminal { get; }
 
-    public nuint Handle { get; }
+    public TerminalInterop.TerminalDescriptor* Descriptor { get; }
 
-    public override sealed Stream Stream { get; }
+    public override Stream Stream { get; }
 
-    public override sealed TextWriter TextWriter { get; }
+    public override TextWriter TextWriter { get; }
 
-    public override sealed bool IsValid { get; }
+    public override bool IsValid { get; }
 
-    public override sealed bool IsInteractive { get; }
+    public override bool IsInteractive { get; }
 
     private readonly SemaphoreSlim _semaphore;
 
     private readonly Action<nuint, CancellationToken>? _cancellationHook;
 
     public NativeTerminalWriter(
         NativeVirtualTerminal terminal,
-        nuint handle,
+        TerminalInterop.TerminalDescriptor* descriptor,
         SemaphoreSlim semaphore,
         Action<nuint, CancellationToken>? cancellationHook)
     {
         Terminal = terminal;
-        Handle = handle;
+        Descriptor = descriptor;
         _semaphore = semaphore;
         _cancellationHook = cancellationHook;
         Stream = new SynchronizedStream(new TerminalOutputStream(this));
@@ -39,11 +39,11 @@ public NativeTerminalWriter(
             {
                 AutoFlush = true,
             });
-        IsValid = TerminalInterop.IsValid(handle, write: true);
-        IsInteractive = TerminalInterop.IsInteractive(handle);
+        IsValid = TerminalInterop.IsValid(descriptor, write: true);
+        IsInteractive = TerminalInterop.IsInteractive(descriptor);
     }
 
-    private unsafe int WritePartialNative(scoped ReadOnlySpan<byte> buffer, CancellationToken cancellationToken)
+    private int WritePartialNative(scoped ReadOnlySpan<byte> buffer, CancellationToken cancellationToken)
     {
         using var guard = Terminal.Control.Guard();
 
@@ -54,12 +54,12 @@ private unsafe int WritePartialNative(scoped ReadOnlySpan<byte> buffer, Cancella
 
         using (_semaphore.Enter(cancellationToken))
         {
-            _cancellationHook?.Invoke(Handle, cancellationToken);
+            _cancellationHook?.Invoke((nuint)Descriptor, cancellationToken);
 
             int progress;
 
             fixed (byte* p = buffer)
-                TerminalInterop.Write(Handle, p, buffer.Length, &progress).ThrowIfError();
+                TerminalInterop.Write(Descriptor, p, buffer.Length, &progress).ThrowIfError();
 
             return progress;
         }

src/core/Terminals/NativeVirtualTerminal.cs

@@ -14,8 +14,6 @@ internal abstract class NativeVirtualTerminal : SystemVirtualTerminal
 
     public override sealed NativeTerminalWriter TerminalOut { get; }
 
-    [SuppressMessage("", "CA2000")]
-    [SuppressMessage("", "CA2214")]
     private protected unsafe NativeVirtualTerminal()
     {
         // Ensure that the native library is fully loaded and initialized before we do anything terminal-related.
@@ -24,13 +22,23 @@ private protected unsafe NativeVirtualTerminal()
         var inLock = new SemaphoreSlim(1, 1);
         var outLock = new SemaphoreSlim(1, 1);
 
-        nuint stdIn;
-        nuint stdOut;
-        nuint stdErr;
-        nuint ttyIn;
-        nuint ttyOut;
+        TerminalInterop.TerminalDescriptor* stdIn;
+        TerminalInterop.TerminalDescriptor* stdOut;
+        TerminalInterop.TerminalDescriptor* stdErr;
+        TerminalInterop.TerminalDescriptor* ttyIn;
+        TerminalInterop.TerminalDescriptor* ttyOut;
 
-        TerminalInterop.GetHandles(&stdIn, &stdOut, &stdErr, &ttyIn, &ttyOut);
+        TerminalInterop.GetDescriptors(&stdIn, &stdOut, &stdErr, &ttyIn, &ttyOut);
+
+        NativeTerminalReader CreateReader(TerminalInterop.TerminalDescriptor* descriptor, SemaphoreSlim semaphore)
+        {
+            return new(this, descriptor, semaphore, CreateCancellationHook(write: false));
+        }
+
+        NativeTerminalWriter CreateWriter(TerminalInterop.TerminalDescriptor* descriptor, SemaphoreSlim semaphore)
+        {
+            return new(this, descriptor, semaphore, CreateCancellationHook(write: true));
+        }
 
         StandardIn = CreateReader(stdIn, inLock);
         StandardOut = CreateWriter(stdOut, outLock);
@@ -39,9 +47,7 @@ private protected unsafe NativeVirtualTerminal()
         TerminalOut = CreateWriter(ttyOut, outLock);
     }
 
-    protected abstract NativeTerminalReader CreateReader(nuint handle, SemaphoreSlim semaphore);
-
-    protected abstract NativeTerminalWriter CreateWriter(nuint handle, SemaphoreSlim semaphore);
+    protected abstract Action<nuint, CancellationToken>? CreateCancellationHook(bool write);
 
     private protected override sealed unsafe Size? QuerySize()
     {

src/core/Terminals/UnixCancellationPipe.cs

@@ -5,6 +5,8 @@ namespace Vezel.Cathode.Terminals;
 [SuppressMessage("", "CA1001")]
 internal sealed class UnixCancellationPipe
 {
+    // TODO: Move this logic to src/native/driver-unix.c.
+
     private readonly AnonymousPipeServerStream _server;
 
     private readonly AnonymousPipeClientStream _client;
@@ -18,7 +20,7 @@ public UnixCancellationPipe(bool write)
         _write = write;
     }
 
-    public unsafe void PollWithCancellation(nuint handle, CancellationToken cancellationToken)
+    public unsafe void PollWithCancellation(int fd, CancellationToken cancellationToken)
     {
         // Note that the runtime sets up a SIGPIPE handler for us.
 
@@ -31,8 +33,8 @@ public unsafe void PollWithCancellation(nuint handle, CancellationToken cancella
         {
             var handles = stackalloc[]
             {
-                (nuint)pipeHandle.DangerousGetHandle(),
-                handle,
+                (int)pipeHandle.DangerousGetHandle(),
+                fd,
             };
             var results = stackalloc bool[2];
 

src/core/Terminals/UnixVirtualTerminal.cs

@@ -6,13 +6,10 @@ internal sealed class UnixVirtualTerminal : NativeVirtualTerminal
 
     public static UnixVirtualTerminal Instance { get; } = new();
 
-    [SuppressMessage("", "IDE0052")]
     private readonly PosixSignalRegistration _sigWinch;
 
-    [SuppressMessage("", "IDE0052")]
     private readonly PosixSignalRegistration _sigCont;
 
-    [SuppressMessage("", "IDE0052")]
     private readonly PosixSignalRegistration _sigChld;
 
     public unsafe UnixVirtualTerminal()
@@ -57,17 +54,14 @@ void HandleSignal(PosixSignalContext context)
         _sigChld = PosixSignalRegistration.Create(PosixSignal.SIGCHLD, HandleSignal);
     }
 
-    protected override NativeTerminalReader CreateReader(nuint handle, SemaphoreSlim semaphore)
+    protected override unsafe Action<nuint, CancellationToken> CreateCancellationHook(bool write)
     {
-        var pipe = new UnixCancellationPipe(write: false);
+        var pipe = new UnixCancellationPipe(write);
 
-        return new(this, handle, semaphore, cancellationHook: pipe.PollWithCancellation);
-    }
-
-    protected override NativeTerminalWriter CreateWriter(nuint handle, SemaphoreSlim semaphore)
-    {
-        var pipe = new UnixCancellationPipe(write: true);
-
-        return new(this, handle, semaphore, cancellationHook: pipe.PollWithCancellation);
+        return (descriptor, cancellationToken) =>
+        {
+            if (cancellationToken.CanBeCanceled)
+                pipe.PollWithCancellation(*(int*)descriptor, cancellationToken);
+        };
     }
 }

src/core/Terminals/WindowsVirtualTerminal.cs

@@ -20,13 +20,8 @@ private WindowsVirtualTerminal()
     {
     }
 
-    protected override NativeTerminalReader CreateReader(nuint handle, SemaphoreSlim semaphore)
+    protected override unsafe Action<nuint, CancellationToken>? CreateCancellationHook(bool write)
     {
-        return new(this, handle, semaphore, cancellationHook: null);
-    }
-
-    protected override NativeTerminalWriter CreateWriter(nuint handle, SemaphoreSlim semaphore)
-    {
-        return new(this, handle, semaphore, cancellationHook: null);
+        return null;
     }
 }