| // Copyright 2009 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // The tar package implements access to tar archives. |
| // It aims to cover most of the variations, including those produced |
| // by GNU and BSD tars. |
| // |
| // References: |
| // http://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5 |
| // http://www.gnu.org/software/tar/manual/html_node/Standard.html |
| package tar |
| |
| const ( |
| blockSize = 512 |
| |
| // Types |
| TypeReg = '0' |
| TypeRegA = '\x00' |
| TypeLink = '1' |
| TypeSymlink = '2' |
| TypeChar = '3' |
| TypeBlock = '4' |
| TypeDir = '5' |
| TypeFifo = '6' |
| TypeCont = '7' |
| TypeXHeader = 'x' |
| TypeXGlobalHeader = 'g' |
| ) |
| |
| // A Header represents a single header in a tar archive. |
| // Some fields may not be populated. |
| type Header struct { |
| Name string |
| Mode int64 |
| Uid int |
| Gid int |
| Size int64 |
| Mtime int64 |
| Typeflag byte |
| Linkname string |
| Uname string |
| Gname string |
| Devmajor int64 |
| Devminor int64 |
| Atime int64 |
| Ctime int64 |
| } |
| |
| var zeroBlock = make([]byte, blockSize) |
| |
| // POSIX specifies a sum of the unsigned byte values, but the Sun tar uses signed byte values. |
| // We compute and return both. |
| func checksum(header []byte) (unsigned int64, signed int64) { |
| for i := 0; i < len(header); i++ { |
| if i == 148 { |
| // The chksum field (header[148:156]) is special: it should be treated as space bytes. |
| unsigned += ' ' * 8 |
| signed += ' ' * 8 |
| i += 7 |
| continue |
| } |
| unsigned += int64(header[i]) |
| signed += int64(int8(header[i])) |
| } |
| return |
| } |
| |
| type slicer []byte |
| |
| func (sp *slicer) next(n int) (b []byte) { |
| s := *sp |
| b, *sp = s[0:n], s[n:] |
| return |
| } |