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https://github.com/vbatts/tar-split.git
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old.go: no need to keep this sitting here
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parent
72c5103763
commit
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1 changed files with 0 additions and 236 deletions
236
old.go
236
old.go
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@ -1,236 +0,0 @@
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// +build ignore
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package main
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import (
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"bytes"
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"crypto"
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"encoding/json"
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"errors"
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"flag"
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"io"
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"log"
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"os"
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"strconv"
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)
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func main() {
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flag.Parse()
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tarInfos := []TarInfo{}
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for _, arg := range flag.Args() {
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func() {
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// Open the tar archive
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fh, err := os.Open(arg)
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if err != nil {
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log.Fatal(err)
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}
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defer fh.Close()
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fi, err := fh.Stat()
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if err != nil {
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log.Fatal(err)
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}
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ti := TarInfo{
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Name: arg,
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Size: fi.Size(),
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}
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for {
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buf, err := readHeader(fh)
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if err != nil {
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if err == io.EOF {
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break
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}
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log.Fatal(err)
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}
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if !verifyChecksum(buf) {
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log.Fatal(ErrHeader)
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}
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s := slicer(buf)
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name := cString(s.next(100))
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s.next(8) // mode
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s.next(8) // uid
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s.next(8) // gid
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size, err := octal(s.next(12))
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if err != nil {
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log.Fatal(err)
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}
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e := Entry{
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Header: buf,
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Name: name,
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Size: size,
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}
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log.Printf("%#v", e)
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ti.Entries = append(ti.Entries, e)
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// TODO(vbatts) some pax types need further reading, for their headers ...
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// XXX this where it is broken
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if _, err := fh.Seek(size, 1); err != nil {
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log.Fatal(err)
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}
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}
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tarInfos = append(tarInfos, ti)
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}()
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}
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if *flOutputJson != "" {
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fh, err := os.Create(*flOutputJson)
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if err != nil {
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log.Fatal(err)
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}
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defer fh.Close()
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jsonBuf, err := json.Marshal(tarInfos)
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if err != nil {
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log.Fatal(err)
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}
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_, err = fh.Write(jsonBuf)
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if err != nil {
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log.Fatal(err)
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}
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}
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}
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const BlockSize = 512
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var (
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zeroBlock = make([]byte, BlockSize)
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hdrBuff = make([]byte, BlockSize)
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ErrHeader = errors.New("archive/tar: invalid tar header")
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flOutputJson = flag.String("o", "", "output json of the tar archives")
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)
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// cString parses bytes as a NUL-terminated C-style string.
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// If a NUL byte is not found then the whole slice is returned as a string.
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//
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// copied from 'archive/tar/reader.go'
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func cString(b []byte) string {
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n := 0
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for n < len(b) && b[n] != 0 {
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n++
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}
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return string(b[0:n])
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}
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// parse the octal value from the byte array
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//
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// copied from 'archive/tar/reader.go'
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func octal(b []byte) (int64, error) {
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// Check for binary format first.
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if len(b) > 0 && b[0]&0x80 != 0 {
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var x int64
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for i, c := range b {
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if i == 0 {
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c &= 0x7f // ignore signal bit in first byte
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}
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x = x<<8 | int64(c)
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}
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return x, nil
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}
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// Because unused fields are filled with NULs, we need
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// to skip leading NULs. Fields may also be padded with
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// spaces or NULs.
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// So we remove leading and trailing NULs and spaces to
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// be sure.
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b = bytes.Trim(b, " \x00")
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if len(b) == 0 {
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return 0, nil
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}
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x, err := strconv.ParseUint(cString(b), 8, 64)
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return int64(x), err
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}
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// copied from 'archive/tar/reader.go'
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func verifyChecksum(header []byte) bool {
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given, err := octal(header[148:156])
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if err != nil {
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return false
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}
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unsigned, signed := checksum(header)
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return given == unsigned || given == signed
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}
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// POSIX specifies a sum of the unsigned byte values, but the Sun tar uses signed byte values.
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// We compute and return both.
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//
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// copied from 'archive/tar/reader.go'
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func checksum(header []byte) (unsigned int64, signed int64) {
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for i := 0; i < len(header); i++ {
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if i == 148 {
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// The chksum field (header[148:156]) is special: it should be treated as space bytes.
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unsigned += ' ' * 8
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signed += ' ' * 8
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i += 7
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continue
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}
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unsigned += int64(header[i])
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signed += int64(int8(header[i]))
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}
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return
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}
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// copied from 'archive/tar/reader.go'
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type slicer []byte
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// copied from 'archive/tar/reader.go'
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func (sp *slicer) next(n int) (b []byte) {
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s := *sp
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b, *sp = s[0:n], s[n:]
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return
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}
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// readHeader looks for the first header segement from the provided reader
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//
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// partially copied from 'archive/tar/reader.go'
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func readHeader(r io.Reader) ([]byte, error) {
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// prep our buffer
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buf := hdrBuff[:]
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copy(buf, zeroBlock)
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if _, err := io.ReadFull(r, buf); err != nil {
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return nil, err
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}
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// Two blocks of zero bytes marks the end of the archive.
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if bytes.Equal(buf, zeroBlock[0:BlockSize]) {
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if _, err := io.ReadFull(r, buf); err != nil {
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return nil, err
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}
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if bytes.Equal(buf, zeroBlock[0:BlockSize]) {
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return nil, io.EOF
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}
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return nil, ErrHeader // zero block and then non-zero block
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}
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return buf, nil
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}
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type (
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// for a whole tar archive
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TarInfo struct {
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Name string
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Size int64
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Entries []Entry
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// TODO(vbatts) would be nice to satisfy the Reader interface, so that this could be passed directly to tar.Reader
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}
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// each file from the tar archive has it's header copied exactly,
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//and payload of it's file Checksummed if the file size is greater than 0
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Entry struct {
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Pos int64
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Name string
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Header []byte
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Size int64
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Checksum []byte
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Hash crypto.Hash
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// TODO(vbatts) perhaps have info to find the file on disk, to provide an io.Reader
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}
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)
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