main.go

package main

import (
	"io/ioutil"
	"os"
	"os/exec"
	"path"
)

func main() {
	cwd, _ := os.Getwd()
	dir := cwd
	gopath := os.Getenv("GOPATH")
	for {
		if _, err := os.Stat(path.Join(dir, ".gopath")); err == nil {
			gopath, err = String(ioutil.ReadFile(path.Join(dir, ".gopath")))
			if err != nil || gopath == "" {
				gopath = dir
			}
			if !path.IsAbs(gopath) {
				gopath = path.Join(dir, gopath)
			}
			break
		}
		if dir == "/" {
			break
		}
		dir = path.Dir(dir)
	}
	os.Setenv("GOPATH", gopath)
	if len(os.Args) < 2 {
		os.Stdout.WriteString(gopath + "\n")
		os.Exit(0)
	}
	cmd := exec.Command(os.Args[1], os.Args[2:]...)
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.Run()
}

func String(b []byte, err error) (string, error) {
	return string(b), err
}