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jeremybenn |
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package tar implements access to tar archives.
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// It aims to cover most of the variations, including those produced
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// by GNU and BSD tars.
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//
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// References:
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// http://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5
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// http://www.gnu.org/software/tar/manual/html_node/Standard.html
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package tar
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import "time"
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const (
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blockSize = 512
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// Types
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TypeReg = '0' // regular file
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TypeRegA = '\x00' // regular file
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TypeLink = '1' // hard link
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TypeSymlink = '2' // symbolic link
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TypeChar = '3' // character device node
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TypeBlock = '4' // block device node
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TypeDir = '5' // directory
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TypeFifo = '6' // fifo node
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TypeCont = '7' // reserved
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TypeXHeader = 'x' // extended header
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TypeXGlobalHeader = 'g' // global extended header
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)
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// A Header represents a single header in a tar archive.
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// Some fields may not be populated.
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type Header struct {
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Name string // name of header file entry
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Mode int64 // permission and mode bits
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Uid int // user id of owner
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Gid int // group id of owner
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Size int64 // length in bytes
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ModTime time.Time // modified time
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Typeflag byte // type of header entry
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Linkname string // target name of link
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Uname string // user name of owner
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Gname string // group name of owner
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Devmajor int64 // major number of character or block device
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Devminor int64 // minor number of character or block device
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AccessTime time.Time // access time
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ChangeTime time.Time // status change time
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}
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var zeroBlock = make([]byte, blockSize)
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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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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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type slicer []byte
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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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