peek sockets instead of selecting

Signed-off-by: Edoardo Vacchi <evacchi@users.noreply.github.com>

internal/platform/fdset_windows.go

@@ -65,7 +65,7 @@ func (f *FdSet) SetRegular(r WinSockFdSet) {
 	f.regular = r
 }
 
-// Regular returns a WinSockFdSet containing the handles in this FdSet that are pipes.
+// Pipes returns a WinSockFdSet containing the handles in this FdSet that are pipes.
 func (f *FdSet) Pipes() *WinSockFdSet {
 	if f == nil {
 		return nil
@@ -187,13 +187,12 @@ func (f *WinSockFdSet) Get(index int) syscall.Handle {
 	return f.handles[index]
 }
 
-// isSocket returns true if the given file handle is a pipe.
+// isSocket returns true if the given file handle
+// is a pipe.
 func isSocket(fd syscall.Handle) bool {
-	// If the call to GetNamedPipeInfo succeeds then
-	// the handle is a pipe handle, otherwise it is a socket.
 	r, _, errno := syscall.SyscallN(
 		procGetNamedPipeInfo.Addr(),
-		uintptr(unsafe.Pointer(nil)),
+		uintptr(fd),
 		uintptr(unsafe.Pointer(nil)),
 		uintptr(unsafe.Pointer(nil)),
 		uintptr(unsafe.Pointer(nil)))

internal/sysfs/select_windows.go

@@ -95,26 +95,6 @@ func selectAllHandles(ctx context.Context, r, w, e *platform.FdSet, duration *ti
 			afterCh = after.C
 		}
 
-		// winsock_select is a blocking call. We spin a goroutine
-		// and write back to a channel the result. We consume
-		// this result in the for loop together with the polling
-		// routines.
-		type selectResult struct {
-			n     int
-			errno sys.Errno
-		}
-
-		winsockSelectCh := make(chan selectResult, 1)
-		defer close(winsockSelectCh)
-
-		go func() {
-			res := selectResult{}
-			res.n, res.errno = winsock_select(rs, ws, es, duration)
-			winsockSelectCh <- res
-		}()
-
-		nsocks := 0
-
 	outer:
 		for {
 			select {
@@ -125,24 +105,15 @@ func selectAllHandles(ctx context.Context, r, w, e *platform.FdSet, duration *ti
 			case <-tickCh:
 				rp, errno = peekAllPipes(r.Pipes())
 				npipes = rp.Count()
-				if errno != 0 || npipes > 0 {
+				if errno != 0 {
 					break outer
 				}
-			case res := <-winsockSelectCh:
-				nsocks = res.n
-				if res.errno != 0 {
+
+				zero := time.Duration(0)
+				nsocks, errno = winsock_select(rs, ws, es, &zero)
+				if errno != 0 {
 					break outer
 				}
-				// winsock_select has returned with no result, ignore
-				// and wait for the other pipes.
-				if nsocks == 0 {
-					continue
-				}
-				// If select has return successfully we peek for the last time at the other pipes
-				// to see if data is available and return the sum.
-				rp, errno = peekAllPipes(r.Pipes())
-				npipes = rp.Count()
-				break outer
 			}
 		}
 	}