You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: user_unix.go
    path of file: ./repos/podman/vendor/github.com/containers/buildah/pkg/chrootuser
    
    the code of the file until where you have to start completion: //go:build linux || freebsd
// +build linux freebsd

package chrootuser

import (
	"bufio"
	"flag"
	"fmt"
	"io"
	"os"
	"os/exec"
	"os/user"
	"strconv"
	"strings"
	"sync"

	"github.com/containers/storage/pkg
    
func openChrootedFileMain() {
	status := 0
	flag.Parse()
	if len(flag.Args()) < 1 {
		os.Exit(1)
	}
	// Our first parameter is the directory to chroot into.
	if err := unix.Chdir(flag.Arg(0)); err != nil {
		fmt.Fprintf(os.Stderr, "chdir(): %v", err)
		os.Exit(1)
	}
	if err := unix.Chroot(flag.Arg(0)); err != nil {
		fmt.Fprintf(os.Stderr, "chroot(): %v", err)
		os.Exit(1)
	}
	// Anything else is a file we want to dump out.
	for _, filename := range flag.Args()[1:] {
		f, err := os.Open(filename)
		if err != nil {
			fmt.Fprintf(os.Stderr, "open(%q): %v", filename, err)
			status = 1
			continue
		}
		_, err = io.Copy(os.Stdout, f)
		if err != nil {
			fmt.Fprintf(os.Stderr, "read(%q): %v", filename, err)
		}
		f.Close()
	}
	os.Exit(status)
}