// 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; }