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u-root.go
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// Copyright 2015-2018 the u-root Authors. All rights reserved
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Command u-root builds CPIO archives with the given files and Go commands.
package main
import (
"errors"
"flag"
"fmt"
"log"
"log/slog"
"os"
"runtime"
"github.com/dustin/go-humanize"
"github.com/u-root/gobusybox/src/pkg/golang"
"github.com/u-root/mkuimage/uimage"
"github.com/u-root/mkuimage/uimage/mkuimage"
"github.com/u-root/uio/llog"
)
var (
errEmptyFilesArg = errors.New("empty argument to -files")
)
// checkArgs checks for common mistakes that cause confusion.
// 1. -files as the last argument
// 2. -files followed by any switch, indicating a shell expansion problem
// This is usually caused by Makfiles structured as follows
// u-root -files `which ethtool` -files `which bash`
// if ethtool is not installed, the expansion yields
// u-root -files -files `which bash`
// and the rather confusing error message
// 16:14:51 Skipping /usr/bin/bash because it is not a directory
// which, in practice, nobody understands
func checkArgs(args ...string) error {
if len(args) == 0 {
return nil
}
if args[len(args)-1] == "-files" {
return fmt.Errorf("last argument is -files:%w", errEmptyFilesArg)
}
// We know the last arg is not -files; scan the arguments for -files
// followed by a switch.
for i := 0; i < len(args)-1; i++ {
if args[i] == "-files" && args[i+1][0] == '-' {
return fmt.Errorf("-files argument %d is followed by a switch: %w", i, errEmptyFilesArg)
}
}
return nil
}
func main() {
log.SetFlags(log.Ltime)
if err := checkArgs(os.Args...); err != nil {
log.Fatal(err)
}
env := golang.Default(golang.DisableCGO())
f := &mkuimage.Flags{
Commands: mkuimage.CommandFlags{Builder: "bb"},
ArchiveFormat: "cpio",
OutputFile: defaultFile(env),
}
f.RegisterFlags(flag.CommandLine)
l := llog.Default()
l.RegisterVerboseFlag(flag.CommandLine, "v", slog.LevelDebug)
tf := &mkuimage.TemplateFlags{}
tf.RegisterFlags(flag.CommandLine)
flag.Parse()
// Set defaults.
m := []uimage.Modifier{
uimage.WithReplaceEnv(env),
uimage.WithBaseArchive(uimage.DefaultRamfs()),
uimage.WithCPIOOutput(defaultFile(env)),
uimage.WithInit("init"),
uimage.WithShellBang(runtime.GOOS == "plan9" || os.Getenv("GOOS") == "plan9"),
}
if golang.Default().GOOS != "plan9" {
m = append(m, uimage.WithShell("gosh"))
}
pkgs := flag.Args()
// Only add default packages if no config template was given.
//
// Otherwise, the template can't erase the default packages and all
// templates would be forced to use cmds/core/*.
if len(pkgs) == 0 && tf.Config == "" {
pkgs = []string{"github.com/u-root/u-root/cmds/core/*"}
}
if err := mkuimage.CreateUimage(l, m, tf, f, pkgs); err != nil {
l.Errorf("mkuimage error: %v", err)
os.Exit(1)
}
if stat, err := os.Stat(f.OutputFile); err == nil && f.ArchiveFormat == "cpio" {
l.Infof("Successfully built %q (size %d bytes -- %s).", f.OutputFile, stat.Size(), humanize.IBytes(uint64(stat.Size())))
}
}
func defaultFile(env *golang.Environ) string {
if len(env.GOOS) == 0 || len(env.GOARCH) == 0 {
return "/tmp/initramfs.cpio"
}
return fmt.Sprintf("/tmp/initramfs.%s_%s.cpio", env.GOOS, env.GOARCH)
}