undocker/main.go

69 lines
1.4 KiB
Go

package main
import (
"errors"
"os"
goflags "github.com/jessevdk/go-flags"
"github.com/motiejus/code/undocker/rootfs"
"go.uber.org/multierr"
)
type (
params struct {
RootFS cmdRootFS `command:"rootfs" description:"Unpack a docker container image to a single filesystem tarball"`
Manifest cmdManifest `command:"manifest"`
}
cmdManifest struct{} // stub
)
func main() {
if err := run(os.Args); err != nil {
os.Exit(1)
}
os.Exit(0)
}
func run(args []string) error {
var opts params
if _, err := goflags.ParseArgs(&opts, args[1:]); err != nil {
return err
}
return nil
}
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")
}
in, err := os.Open(string(r.PositionalArgs.Infile))
if err != nil {
return err
}
defer func() { err = multierr.Append(err, in.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.RootFS(in, out)
}