Add cruntar - untar for ChromeOS.

README.md

@@ -19,6 +19,8 @@ Contents:
                     the time to expiry and checking for revocations.
         clustersh/  Run commands or transfer files across multiple
                     servers via SSH.
+        cruntar/    Untar an archive with hard links, copying instead of
+                    linking.
         csrpubdump/ Dump the public key from an X.509 certificate request.
         fragment/   Print a fragment of a file.
         jlp/        JSON linter/prettifier.

cmd/cruntar/README

@@ -0,0 +1,20 @@
+ChromeOS untar
+
+This is a tool that is intended to support untarring on SquashFS file
+systems. In particular, every time it encounters a hard link, it
+will just create a copy of the file.
+
+Usage: cruntar [-jmvpz] archive [dest]
+
+Flags:
+        -a      Shortcut for -m -p: preserve owners and file mode.
+        -j      The archive is compressed with bzip2.
+        -m      Preserve file modes.
+        -p      Preserve ownership.
+        -v      Print the name of each file as it is being processed.
+        -z      The archive is compressed with gzip.
+
+I wrote this after running into problems with untarring the
+gcc-arm-eabi-none toolchain. The shared storage in Termux under
+ChromeOS doesn't support hard links, so I opted to just make a copy
+rather than dealing with links and whatnot.

cmd/cruntar/main.go

@@ -0,0 +1,265 @@
+package main
+
+import (
+	"archive/tar"
+	"compress/bzip2"
+	"compress/gzip"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"github.com/kisom/goutils/die"
+)
+
+var (
+	preserveOwners bool
+	preserveMode bool
+	verbose bool
+)
+
+func setupFile(hdr *tar.Header, file *os.File) error {
+	if preserveMode {
+		if verbose {
+			fmt.Printf("\tchmod %0#o\n", hdr.Mode)
+		}
+		err := file.Chmod(os.FileMode(hdr.Mode))
+		if err != nil {
+			return err
+		}
+	}
+	
+	if preserveOwners {
+		fmt.Printf("\tchown %d:%d\n", hdr.Uid, hdr.Gid)
+		err := file.Chown(hdr.Uid, hdr.Gid)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func linkTarget(target, top string) string {
+	if filepath.IsAbs(target) {
+		return target
+	}
+
+	return filepath.Clean(filepath.Join(target, top))
+}
+
+func processFile(tfr *tar.Reader, hdr *tar.Header, top string) error {
+	if verbose {
+		fmt.Println(hdr.Name)
+	}
+	filePath := filepath.Clean(filepath.Join(top, hdr.Name))
+	switch hdr.Typeflag {
+	case tar.TypeReg, tar.TypeRegA:
+		file, err := os.Create(filePath)
+		if err != nil {
+			return err
+		}
+
+		_, err = io.Copy(file, tfr)
+		if err != nil {
+			return err
+		}
+
+		err = setupFile(hdr, file)
+		if err != nil {
+			return err
+		}
+	case tar.TypeLink:
+		file, err := os.Create(filePath)
+		if err != nil {
+			return err
+		}
+
+		source, err := os.Open(hdr.Linkname)
+		if err != nil {
+			return err
+		}
+
+		_, err = io.Copy(file, source)
+		if err != nil {
+			return err
+		}
+
+		err = setupFile(hdr, file)
+		if err != nil {
+			return err
+		}
+	case tar.TypeSymlink:
+		err := os.Symlink(linkTarget(hdr.Linkname, top), filePath)
+		if err != nil {
+			return err
+		}
+	case tar.TypeDir:
+		err := os.MkdirAll(filePath, os.FileMode(hdr.Mode))
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+var compression = map[string]bool{
+	"gzip":  false,
+	"bzip2": false,
+}
+
+type bzipCloser struct {
+	r io.Reader
+}
+
+func (brc *bzipCloser) Read(p []byte) (int, error) {
+	return brc.r.Read(p)
+}
+
+func (brc *bzipCloser) Close() error {
+	return nil
+}
+
+func newBzipCloser(r io.ReadCloser) (io.ReadCloser, error) {
+	br := bzip2.NewReader(r)
+	return &bzipCloser{r: br}, nil
+}
+
+var compressFuncs = map[string]func(io.ReadCloser) (io.ReadCloser, error){
+	"gzip":  func(r io.ReadCloser) (io.ReadCloser, error) { return gzip.NewReader(r) },
+	"bzip2": newBzipCloser,
+}
+
+func verifyCompression() bool {
+	var compressed bool
+	for _, v := range compression {
+		if compressed && v {
+			return false
+		}
+		compressed = compressed || v
+	}
+	return true
+}
+
+func getReader(r io.ReadCloser) (io.ReadCloser, error) {
+	for c, v := range compression {
+		if v {
+			return compressFuncs[c](r)
+		}
+	}
+
+	return r, nil
+}
+
+func openArchive(path string) (io.ReadCloser, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+
+	r, err := getReader(file)
+	if err != nil {
+		return nil, err
+	}
+
+	return r, nil
+}
+
+var compressFlags struct {
+	z bool
+	j bool
+}
+
+func parseCompressFlags() error {
+	if compressFlags.z {
+		compression["gzip"] = true
+	}
+
+	if compressFlags.j {
+		compression["bzip2"] = true
+	}
+
+	if !verifyCompression() {
+		return errors.New("multiple compression formats specified")
+	}
+
+	return nil
+}
+
+func usage(w io.Writer) {
+	fmt.Fprintf(w, `ChromeOS untar
+
+This is a tool that is intended to support untarring on SquashFS file
+systems. In particular, every time it encounters a hard link, it
+will just create a copy of the file.
+
+Usage: cruntar [-jmvpz] archive [dest]
+
+Flags:
+	-a	Shortcut for -m -p: preserve owners and file mode.
+	-j	The archive is compressed with bzip2.
+	-m	Preserve file modes.
+	-p	Preserve ownership.
+	-v	Print the name of each file as it is being processed.
+	-z	The archive is compressed with gzip.
+`)
+}
+
+func init() {
+	flag.Usage = func() { usage(os.Stderr) }
+}
+
+func main() {
+	var archive, help bool
+	flag.BoolVar(&archive, "a", false, "Shortcut for -m -p: preserve owners and file mode.")
+	flag.BoolVar(&help, "h", false, "print a help message")
+	flag.BoolVar(&compressFlags.j, "j", false, "bzip2 compression")
+	flag.BoolVar(&preserveMode, "m", false, "preserve file modes")
+	flag.BoolVar(&preserveOwners, "p", false, "preserve ownership")
+	flag.BoolVar(&verbose, "v", false, "verbose mode")
+	flag.BoolVar(&compressFlags.z, "z", false, "gzip compression")
+	flag.Parse()
+
+	if help {
+		usage(os.Stdout)
+		os.Exit(0)
+	}
+	
+	if archive {
+		preserveMode = true
+		preserveOwners = true
+	}
+
+	err := parseCompressFlags()
+	die.If(err)
+
+	if flag.NArg() == 0 {
+		return
+	}
+
+	top := "./"
+	if flag.NArg() > 1 {
+		top = flag.Arg(1)
+	}
+
+	r, err := openArchive(flag.Arg(0))
+	die.If(err)
+
+	tfr := tar.NewReader(r)
+	for {
+		hdr, err := tfr.Next()
+		if err == io.EOF {
+			break
+		}
+		die.If(err)
+
+		err = processFile(tfr, hdr, top)
+		die.If(err)
+
+	}
+
+	r.Close()
+}