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

cmd/tar-split/README.md

@@ -0,0 +1,25 @@
+## 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
+```
+
+

cmd/tar-split/main.go

@@ -0,0 +1,175 @@
+// 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)
+}