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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 int64;
Gid int64;
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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