package svn2git2aur

import (
	"os/exec"
	"bytes"
)

func pipeline(cmds ...*exec.Cmd) (err error) {
	for i, cmd := range cmds[:len(cmds)-1] {
		cmds[i+1].Stdin, err = cmd.StdoutPipe()
		if err != nil {
			return
		}
	}

	stderr := make([]bytes.Buffer, len(cmds))
	for i, cmd := range cmds {
		cmd.Stderr = &stderr[i]
		if err = cmd.Start(); err != nil {
			break
		}
	}

	for i, cmd := range cmds {
		if cmd.Process == nil {
			continue
		}
		if _err := cmd.Wait(); _err != nil {
			if ee, ok := _err.(*exec.ExitError); ok {
				ee.Stderr = stderr[i].Bytes()
			}
			if err != nil {
				err = _err
			}
		}
	}
	return
}