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// 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
}
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