307 lines
7.3 KiB
Go
307 lines
7.3 KiB
Go
package rardecode
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import (
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"bufio"
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"bytes"
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"errors"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"regexp"
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"strconv"
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"strings"
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)
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const (
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maxSfxSize = 0x100000 // maximum number of bytes to read when searching for RAR signature
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sigPrefix = "Rar!\x1A\x07"
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fileFmt15 = iota + 1 // Version 1.5 archive file format
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fileFmt50 // Version 5.0 archive file format
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)
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var (
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errNoSig = errors.New("rardecode: RAR signature not found")
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errVerMismatch = errors.New("rardecode: volume version mistmatch")
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errCorruptHeader = errors.New("rardecode: corrupt block header")
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errCorruptFileHeader = errors.New("rardecode: corrupt file header")
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errBadHeaderCrc = errors.New("rardecode: bad header crc")
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errUnknownArc = errors.New("rardecode: unknown archive version")
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errUnknownDecoder = errors.New("rardecode: unknown decoder version")
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errUnsupportedDecoder = errors.New("rardecode: unsupported decoder version")
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errArchiveContinues = errors.New("rardecode: archive continues in next volume")
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errArchiveEnd = errors.New("rardecode: archive end reached")
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errDecoderOutOfData = errors.New("rardecode: decoder expected more data than is in packed file")
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reDigits = regexp.MustCompile(`\d+`)
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)
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type readBuf []byte
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func (b *readBuf) byte() byte {
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v := (*b)[0]
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*b = (*b)[1:]
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return v
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}
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func (b *readBuf) uint16() uint16 {
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v := uint16((*b)[0]) | uint16((*b)[1])<<8
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*b = (*b)[2:]
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return v
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}
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func (b *readBuf) uint32() uint32 {
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v := uint32((*b)[0]) | uint32((*b)[1])<<8 | uint32((*b)[2])<<16 | uint32((*b)[3])<<24
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*b = (*b)[4:]
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return v
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}
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func (b *readBuf) bytes(n int) []byte {
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v := (*b)[:n]
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*b = (*b)[n:]
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return v
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}
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func (b *readBuf) uvarint() uint64 {
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var x uint64
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var s uint
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for i, n := range *b {
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if n < 0x80 {
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*b = (*b)[i+1:]
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return x | uint64(n)<<s
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}
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x |= uint64(n&0x7f) << s
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s += 7
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}
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// if we run out of bytes, just return 0
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*b = (*b)[len(*b):]
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return 0
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}
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// readFull wraps io.ReadFull to return io.ErrUnexpectedEOF instead
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// of io.EOF when 0 bytes are read.
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func readFull(r io.Reader, buf []byte) error {
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_, err := io.ReadFull(r, buf)
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if err == io.EOF {
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return io.ErrUnexpectedEOF
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}
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return err
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}
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// findSig searches for the RAR signature and version at the beginning of a file.
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// It searches no more than maxSfxSize bytes.
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func findSig(br *bufio.Reader) (int, error) {
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for n := 0; n <= maxSfxSize; {
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b, err := br.ReadSlice(sigPrefix[0])
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n += len(b)
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if err == bufio.ErrBufferFull {
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continue
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} else if err != nil {
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if err == io.EOF {
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err = errNoSig
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}
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return 0, err
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}
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b, err = br.Peek(len(sigPrefix[1:]) + 2)
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if err != nil {
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if err == io.EOF {
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err = errNoSig
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}
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return 0, err
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}
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if !bytes.HasPrefix(b, []byte(sigPrefix[1:])) {
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continue
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}
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b = b[len(sigPrefix)-1:]
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var ver int
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switch {
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case b[0] == 0:
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ver = fileFmt15
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case b[0] == 1 && b[1] == 0:
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ver = fileFmt50
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default:
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continue
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}
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_, _ = br.ReadSlice('\x00')
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return ver, nil
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}
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return 0, errNoSig
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}
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// volume extends a fileBlockReader to be used across multiple
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// files in a multi-volume archive
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type volume struct {
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fileBlockReader
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f *os.File // current file handle
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br *bufio.Reader // buffered reader for current volume file
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dir string // volume directory
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file string // current volume file
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num int // volume number
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old bool // uses old naming scheme
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}
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// nextVolName updates name to the next filename in the archive.
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func (v *volume) nextVolName() {
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if v.num == 0 {
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// check file extensions
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i := strings.LastIndex(v.file, ".")
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if i < 0 {
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// no file extension, add one
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i = len(v.file)
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v.file += ".rar"
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} else {
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ext := strings.ToLower(v.file[i+1:])
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// replace with .rar for empty extensions & self extracting archives
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if ext == "" || ext == "exe" || ext == "sfx" {
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v.file = v.file[:i+1] + "rar"
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}
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}
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if a, ok := v.fileBlockReader.(*archive15); ok {
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v.old = a.old
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}
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// new naming scheme must have volume number in filename
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if !v.old && reDigits.FindStringIndex(v.file) == nil {
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v.old = true
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}
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// For old style naming if 2nd and 3rd character of file extension is not a digit replace
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// with "00" and ignore any trailing characters.
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if v.old && (len(v.file) < i+4 || v.file[i+2] < '0' || v.file[i+2] > '9' || v.file[i+3] < '0' || v.file[i+3] > '9') {
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v.file = v.file[:i+2] + "00"
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return
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}
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}
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// new style volume naming
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if !v.old {
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// find all numbers in volume name
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m := reDigits.FindAllStringIndex(v.file, -1)
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if l := len(m); l > 1 {
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// More than 1 match so assume name.part###of###.rar style.
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// Take the last 2 matches where the first is the volume number.
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m = m[l-2 : l]
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if strings.Contains(v.file[m[0][1]:m[1][0]], ".") || !strings.Contains(v.file[:m[0][0]], ".") {
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// Didn't match above style as volume had '.' between the two numbers or didnt have a '.'
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// before the first match. Use the second number as volume number.
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m = m[1:]
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}
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}
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// extract and increment volume number
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lo, hi := m[0][0], m[0][1]
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n, err := strconv.Atoi(v.file[lo:hi])
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if err != nil {
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n = 0
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} else {
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n++
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}
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// volume number must use at least the same number of characters as previous volume
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vol := fmt.Sprintf("%0"+fmt.Sprint(hi-lo)+"d", n)
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v.file = v.file[:lo] + vol + v.file[hi:]
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return
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}
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// old style volume naming
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i := strings.LastIndex(v.file, ".")
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// get file extension
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b := []byte(v.file[i+1:])
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// start incrementing volume number digits from rightmost
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for j := 2; j >= 0; j-- {
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if b[j] != '9' {
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b[j]++
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break
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}
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// digit overflow
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if j == 0 {
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// last character before '.'
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b[j] = 'A'
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} else {
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// set to '0' and loop to next character
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b[j] = '0'
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}
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}
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v.file = v.file[:i+1] + string(b)
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}
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func (v *volume) next() (*fileBlockHeader, error) {
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for {
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var atEOF bool
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h, err := v.fileBlockReader.next()
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switch err {
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case errArchiveContinues:
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case io.EOF:
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// Read all of volume without finding an end block. The only way
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// to tell if the archive continues is to try to open the next volume.
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atEOF = true
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default:
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return h, err
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}
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v.f.Close()
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v.nextVolName()
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v.f, err = os.Open(v.dir + v.file) // Open next volume file
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if err != nil {
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if atEOF && os.IsNotExist(err) {
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// volume not found so assume that the archive has ended
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return nil, io.EOF
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}
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return nil, err
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}
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v.num++
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v.br.Reset(v.f)
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ver, err := findSig(v.br)
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if err != nil {
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return nil, err
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}
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if v.version() != ver {
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return nil, errVerMismatch
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}
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v.reset() // reset encryption
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}
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}
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func (v *volume) Close() error {
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// may be nil if os.Open fails in next()
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if v.f == nil {
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return nil
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}
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return v.f.Close()
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}
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func openVolume(name, password string) (*volume, error) {
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var err error
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v := new(volume)
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v.dir, v.file = filepath.Split(name)
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v.f, err = os.Open(name)
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if err != nil {
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return nil, err
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}
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v.br = bufio.NewReader(v.f)
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v.fileBlockReader, err = newFileBlockReader(v.br, password)
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if err != nil {
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v.f.Close()
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return nil, err
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}
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return v, nil
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}
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func newFileBlockReader(br *bufio.Reader, pass string) (fileBlockReader, error) {
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runes := []rune(pass)
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if len(runes) > maxPassword {
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pass = string(runes[:maxPassword])
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}
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ver, err := findSig(br)
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if err != nil {
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return nil, err
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}
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switch ver {
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case fileFmt15:
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return newArchive15(br, pass), nil
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case fileFmt50:
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return newArchive50(br, pass), nil
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}
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return nil, errUnknownArc
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}
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