package cmdrootfs import ( "errors" "os" goflags "github.com/jessevdk/go-flags" "github.com/motiejus/code/undocker/rootfs" "go.uber.org/multierr" ) type CmdRootFS struct { PositionalArgs struct { Infile goflags.Filename `long:"infile" description:"Input tarball"` Outfile string `long:"outfile" description:"Output path, stdout is '-'"` } `positional-args:"yes" required:"yes"` } func (r *CmdRootFS) Execute(args []string) (err error) { if len(args) != 0 { return errors.New("too many args") } rd, err := os.Open(string(r.PositionalArgs.Infile)) if err != nil { return err } defer func() { err = multierr.Append(err, rd.Close()) }() var out *os.File outf := string(r.PositionalArgs.Outfile) if outf == "-" { out = os.Stdout } else { out, err = os.Create(outf) if err != nil { return err } } defer func() { err = multierr.Append(err, out.Close()) }() return rootfs.New(rd).WriteTo(out) }