move rootfs, add gofmt

BUILD

@@ -2,7 +2,10 @@ load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
 
 go_library(
     name = "undocker_lib",
-    srcs = ["main.go"],
+    srcs = [
+        "main.go",
+        "rootfs.go",
+    ],
     importpath = "github.com/motiejus/code/undocker",
     visibility = ["//visibility:private"],
     deps = ["@com_github_jessevdk_go_flags//:go-flags"],

main.go

@@ -1,19 +1,20 @@
 package main
 
 import (
-	"fmt"
 	"os"
-	"errors"
 
 	goflags "github.com/jessevdk/go-flags"
 )
 
-type opts struct {
-	PositionalArgs struct {
-		Infile     goflags.Filename `long:"infile" description:"Docker container tarball"`
-		Outfile string           `long:"outfile" description:"Output tarball"`
-	} `positional-args:"yes" required:"yes"`
-}
+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 {
@@ -23,17 +24,10 @@ func main() {
 }
 
 func run(args []string) error {
-	var flags opts
-	args1, err := goflags.ParseArgs(&flags, args)
-	if err != nil {
+	var opts params
+	if _, err := goflags.ParseArgs(&opts, args[1:]); err != nil {
 		return err
 	}
-	if len(args1) != 0 {
-		return errors.New("too many args")
-	}
-
-	fmt.Printf("infile: %s\n", flags.PositionalArgs.Infile)
-	fmt.Printf("outfile: %s\n", flags.PositionalArgs.Outfile)
 
 	return nil
 }

rootfs.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"errors"
+
+	goflags "github.com/jessevdk/go-flags"
+)
+
+type cmdRootFS struct {
+	PositionalArgs struct {
+		Infile  goflags.Filename `long:"infile" description:"Input tarball"`
+		Outfile string           `long:"outfile" description:"Output tarball (flattened file system)"`
+	} `positional-args:"yes" required:"yes"`
+}
+
+func (r *cmdRootFS) Execute(args []string) error {
+	if len(args) != 0 {
+		return errors.New("too many args")
+	}
+	return nil
+}