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forgejo/vendor/github.com/nwaples/rardecode/archive.go

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