1 files changed, 75 insertions, 0 deletions
diff --git a/libgo/go/archive/tar/common.go b/libgo/go/archive/tar/common.go
new file mode 100644
index 000000000..5b781ff3d
--- /dev/null
+++ b/libgo/go/archive/tar/common.go
@@ -0,0 +1,75 @@
+// 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
+}