Emulate fcntl.ioctl for command TIOCGWINSZ

Author: BCSharp

src/core/IronPython.Modules/fcntl.cs

@@ -27,6 +27,33 @@ a file object.
         """;
 
 
+    // supporting fcntl.ioctl(fileno, termios.TIOCGWINSZ, buf)
+    // where buf = array.array('h', [0, 0, 0, 0])
+    public static object ioctl(CodeContext context, int fd, int cmd, [NotNone] IBufferProtocol arg, int mutate_flag = 1) {
+        if (cmd == PythonTermios.TIOCGWINSZ) {
+            using IPythonBuffer buf = arg.GetBuffer();
+
+            Span<short> winsize = stackalloc short[4];
+            winsize[0] = (short)Console.WindowHeight;
+            winsize[1] = (short)Console.WindowWidth;
+            winsize[2] = (short)Console.BufferHeight;  // buffer height and width are not accurate on macOS
+            winsize[3] = (short)Console.BufferWidth;
+            Span<byte> payload = MemoryMarshal.Cast<short, byte>(winsize);
+
+            if (buf.IsReadOnly || mutate_flag == 0) {
+                byte[] res = buf.ToArray();
+                payload.Slice(0, Math.Min(payload.Length, res.Length)).CopyTo(res);
+                return Bytes.Make(res);
+            } else {
+                var res = buf.AsSpan();
+                payload.Slice(0, Math.Min(payload.Length, res.Length)).CopyTo(res);
+                return 0;
+            }
+        }
+        throw new NotImplementedException($"ioctl: unsupported command {cmd}");
+    }
+
+
     // FD Flags
     public static int FD_CLOEXEC = 1;
     public static int FASYNC => RuntimeInformation.IsOSPlatform(OSPlatform.OSX) ? 0x0040 : 0x2000;