utf8run.go

package main

import (
	"errors"
	"io"
	"os"
	"os/exec"
	"runtime"
	"syscall"

	"github.com/mattn/go-isatty"
	"golang.org/x/text/encoding/japanese"
	"golang.org/x/text/transform"
)

type Writer struct {
	w io.Writer
	t transform.Transformer
}

func (w *Writer) Write(b []byte) (int, error) {
	bb := make([]byte, len(b)*4/2)
	n, _, _ := w.t.Transform(bb, b, false)
	_, err := w.w.Write(bb[:n])
	return len(b), err
}

func run() int {
	var args []string
	if runtime.GOOS == "windows" {
		args = append([]string{"cmd", "/c"}, os.Args[1:]...)
	} else {
		args = append([]string{"sh", "-c"}, os.Args[1:]...)
	}
	cmd := exec.Command(args[0], args[1:]...)
	if isatty.IsTerminal(os.Stdout.Fd()) {
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr
		cmd.Stdin = os.Stdin
	} else {
		cmd.Stdout = &Writer{os.Stdout, japanese.ShiftJIS.NewDecoder()}
		cmd.Stderr = &Writer{os.Stderr, japanese.ShiftJIS.NewDecoder()}
		cmd.Stdin = os.Stdin
	}
	if err := cmd.Run(); err != nil {
		if err, ok := err.(*exec.ExitError); ok {
			if status, ok := err.Sys().(syscall.WaitStatus); ok {
				return status.ExitStatus()
			} else {
				panic(errors.New("Unimplemented for system where exec.ExitError.Sys() is not syscall.WaitStatus."))
			}
		}
	}
	return 0
}

func main() {
	os.Exit(run())
}