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bzimage.go
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bzimage.go
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// Copyright 2012-2018 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.
// bzImage is used to modify bzImage files.
// It reads the image in, applies an operator, and writes a new one out.
//
// Synopsis:
// bzImage [copy <in> <out> ] | [diff <image> <image> ] | [dump <file>] | [initramfs input-bzimage initramfs output-bzimage]
//
// Description:
// Read a bzImage in, change it, write it out, or print info.
package main
import (
"fmt"
"io/ioutil"
"log"
"strings"
flag "github.com/spf13/pflag"
"github.com/u-root/u-root/pkg/bzimage"
)
var argcounts = map[string]int{
"copy": 3,
"diff": 3,
"dump": 2,
"initramfs": 4,
"extract": 3,
}
var (
cmdUsage = "Usage: bzImage [copy <in> <out> ] | [diff <image> <image> ] | [extract <file> <elf-file> ] | [dump <file>] | [initramfs input-bzimage initramfs output-bzimage]"
debug = flag.BoolP("debug", "d", false, "enable debug printing")
)
func usage() {
log.Fatalf(cmdUsage)
}
func main() {
flag.Parse()
if *debug {
bzimage.Debug = log.Printf
}
a := flag.Args()
if len(a) < 2 {
usage()
}
n, ok := argcounts[a[0]]
if !ok || len(a) != n {
usage()
}
var br = &bzimage.BzImage{}
var image []byte
switch a[0] {
case "copy", "diff", "dump", "initramfs", "extract":
var err error
image, err = ioutil.ReadFile(a[1])
if err != nil {
log.Fatal(err)
}
if err = br.UnmarshalBinary(image); err != nil {
log.Fatal(err)
}
}
switch a[0] {
case "copy":
o, err := br.MarshalBinary()
if err != nil {
log.Fatal(err)
}
if len(image) != len(o) {
log.Printf("copy: input len is %d, output len is %d, they have to match", len(image), len(o))
var br2 bzimage.BzImage
if err = br2.UnmarshalBinary(o); err != nil {
log.Fatal(err)
}
fmt.Printf("Input: %s\n", strings.Join(br.Header.Show(), "\n\t"))
fmt.Printf("Output: %s\n", strings.Join(br2.Header.Show(), "\n\t"))
log.Printf("%s", br.Header.Diff(&br2.Header))
log.Fatalf("there is no hope")
}
if err := ioutil.WriteFile(a[2], o, 0666); err != nil {
log.Fatalf("Writing %v: %v", a[2], err)
}
case "diff":
b2, err := ioutil.ReadFile(a[2])
if err != nil {
log.Fatal(err)
}
var br2 = &bzimage.BzImage{}
if err = br2.UnmarshalBinary(b2); err != nil {
log.Fatal(err)
}
fmt.Printf("%s", br.Header.Diff(&br2.Header))
case "dump":
fmt.Printf("%s\n", strings.Join(br.Header.Show(), "\n"))
case "extract":
bzimage.Debug = log.Printf
var i []byte
s, e, err := br.InitRAMFS()
if err != nil {
fmt.Printf("Warning: could not extract initramfs: %v", err)
} else {
i = br.KernelCode[s:e]
}
// Need to add a trailer record to i
fmt.Printf("ramfs is %d bytes", len(i))
for _, v := range []struct {
n string
b []byte
}{
{a[2] + ".boot", br.BootCode},
{a[2] + ".head", br.HeadCode},
{a[2] + ".kern", br.KernelCode},
{a[2] + ".tail", br.TailCode},
{a[2] + ".ramfs", i},
} {
if v.b == nil {
fmt.Printf("Warning: %s is nil", v.n)
continue
}
if err := ioutil.WriteFile(v.n, v.b, 0666); err != nil {
log.Fatalf("Writing %v: %v", v, err)
}
}
case "initramfs":
if err := br.AddInitRAMFS(a[2]); err != nil {
log.Fatal(err)
}
b, err := br.MarshalBinary()
if err != nil {
log.Fatal(err)
}
if err := ioutil.WriteFile(a[3], b, 0644); err != nil {
log.Fatal(err)
}
}
}