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cmd/tar-split: adding a cli tool for asm/disasm

This commit is contained in:
Vincent Batts 2015-07-20 15:51:20 -04:00
parent 6094dcaeca
commit fd84b2fdfd
2 changed files with 200 additions and 0 deletions

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cmd/tar-split/README.md Normal file
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## tar-split utility
## Usage
### Disassembly
```bash
$ sha256sum archive.tar
d734a748db93ec873392470510b8a1c88929abd8fae2540dc43d5b26f7537868 archive.tar
$ mkdir ./x
$ tar-split d --output tar-data.json.gz ./archive.tar | tar -C ./x -x
time="2015-07-20T15:45:04-04:00" level=info msg="created tar-data.json.gz from ./archive.tar (read 204800 bytes)"
```
### Assembly
```bash
$ tar-split a --output new.tar --input ./tar-data.json.gz --path ./x/
INFO[0000] created new.tar from ./x/ and ./tar-data.json.gz (wrote 204800 bytes)
$ sha256sum new.tar
d734a748db93ec873392470510b8a1c88929abd8fae2540dc43d5b26f7537868 new.tar
```

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cmd/tar-split/main.go Normal file
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// go:generate git tag | tail -1
package main
import (
"compress/gzip"
"io"
"os"
"github.com/Sirupsen/logrus"
"github.com/codegangsta/cli"
"github.com/vbatts/tar-split/tar/asm"
"github.com/vbatts/tar-split/tar/storage"
)
func main() {
app := cli.NewApp()
app.Name = "tar-split"
app.Usage = "tar assembly and disassembly utility"
app.Version = "0.9.2"
app.Author = "Vincent Batts"
app.Email = "vbatts@hashbangbash.com"
app.Action = cli.ShowAppHelp
app.Before = func(c *cli.Context) error {
logrus.SetOutput(os.Stderr)
if c.Bool("debug") {
logrus.SetLevel(logrus.DebugLevel)
}
return nil
}
app.Flags = []cli.Flag{
cli.BoolFlag{
Name: "debug, D",
Usage: "debug output",
// defaults to false
},
}
app.Commands = []cli.Command{
{
Name: "disasm",
Aliases: []string{"d"},
Usage: "disassemble the input tar stream",
Action: CommandDisasm,
Flags: []cli.Flag{
cli.StringFlag{
Name: "output",
Value: "tar-data.json.gz",
Usage: "output of disassembled tar stream",
},
},
},
{
Name: "asm",
Aliases: []string{"a"},
Usage: "assemble tar stream",
Action: CommandAsm,
Flags: []cli.Flag{
cli.StringFlag{
Name: "input",
Value: "tar-data.json.gz",
Usage: "input of disassembled tar stream",
},
cli.StringFlag{
Name: "output",
Value: "-",
Usage: "reassembled tar archive",
},
cli.StringFlag{
Name: "path",
Value: "",
Usage: "relative path of extracted tar",
},
},
},
}
if err := app.Run(os.Args); err != nil {
logrus.Fatal(err)
}
}
func CommandDisasm(c *cli.Context) {
if len(c.Args()) != 1 {
logrus.Fatalf("please specify tar to be disabled <NAME|->")
}
if len(c.String("output")) == 0 {
logrus.Fatalf("--output filename must be set")
}
// Set up the tar input stream
var inputStream io.Reader
if c.Args()[0] == "-" {
inputStream = os.Stdin
} else {
fh, err := os.Open(c.Args()[0])
if err != nil {
logrus.Fatal(err)
}
defer fh.Close()
inputStream = fh
}
// Set up the metadata storage
mf, err := os.OpenFile(c.String("output"), os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.FileMode(0600))
if err != nil {
logrus.Fatal(err)
}
defer mf.Close()
mfz := gzip.NewWriter(mf)
defer mfz.Close()
metaPacker := storage.NewJSONPacker(mfz)
// we're passing nil here for the file putter, because the ApplyDiff will
// handle the extraction of the archive
its, err := asm.NewInputTarStream(inputStream, metaPacker, nil)
if err != nil {
logrus.Fatal(err)
}
i, err := io.Copy(os.Stdout, its)
if err != nil {
logrus.Fatal(err)
}
logrus.Infof("created %s from %s (read %d bytes)", c.String("output"), c.Args()[0], i)
}
func CommandAsm(c *cli.Context) {
if len(c.Args()) > 0 {
logrus.Warnf("%d additional arguments passed are ignored", len(c.Args()))
}
if len(c.String("input")) == 0 {
logrus.Fatalf("--input filename must be set")
}
if len(c.String("output")) == 0 {
logrus.Fatalf("--output filename must be set ([FILENAME|-])")
}
if len(c.String("path")) == 0 {
logrus.Fatalf("--path must be set")
}
var outputStream io.Writer
if c.String("output") == "-" {
outputStream = os.Stdout
} else {
fh, err := os.Create(c.String("output"))
if err != nil {
logrus.Fatal(err)
}
defer fh.Close()
outputStream = fh
}
// Get the tar metadata reader
mf, err := os.Open(c.String("input"))
if err != nil {
logrus.Fatal(err)
}
defer mf.Close()
mfz, err := gzip.NewReader(mf)
if err != nil {
logrus.Fatal(err)
}
defer mfz.Close()
metaUnpacker := storage.NewJSONUnpacker(mfz)
// XXX maybe get the absolute path here
fileGetter := storage.NewPathFileGetter(c.String("path"))
ots := asm.NewOutputTarStream(fileGetter, metaUnpacker)
defer ots.Close()
i, err := io.Copy(outputStream, ots)
if err != nil {
logrus.Fatal(err)
}
logrus.Infof("created %s from %s and %s (wrote %d bytes)", c.String("output"), c.String("path"), c.String("input"), i)
}