Move Linux client & common packages into a public repo.

logtail/filch/filch_windows.go

@@ -0,0 +1,44 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package filch
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+)
+
+var kernel32 = syscall.MustLoadDLL("kernel32.dll")
+var procSetStdHandle = kernel32.MustFindProc("SetStdHandle")
+
+func setStdHandle(stdHandle int32, handle syscall.Handle) error {
+	r, _, e := syscall.Syscall(procSetStdHandle.Addr(), 2, uintptr(stdHandle), uintptr(handle), 0)
+	if r == 0 {
+		if e != 0 {
+			return error(e)
+		}
+		return syscall.EINVAL
+	}
+	return nil
+}
+
+func saveStderr() (*os.File, error) {
+	return os.Stderr, nil
+}
+
+func unsaveStderr(f *os.File) error {
+	os.Stderr = f
+	return nil
+}
+
+func dup2Stderr(f *os.File) error {
+	fd := int(f.Fd())
+	err := setStdHandle(syscall.STD_ERROR_HANDLE, syscall.Handle(fd))
+	if err != nil {
+		return fmt.Errorf("dup2Stderr: %w", err)
+	}
+	os.Stderr = f
+	return nil
+}