Initial checkin from CRI-O repo

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

16 files changed, 2702 insertions, 0 deletions

diff --git a/vendor/github.com/vbatts/tar-split/LICENSE b/vendor/github.com/vbatts/tar-split/LICENSE
new file mode 100644
index 000000000..ca03685b1
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/LICENSE
@@ -0,0 +1,28 @@
+Copyright (c) 2015 Vincent Batts, Raleigh, NC, USA
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation
+and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors
+may be used to endorse or promote products derived from this software without
+specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/github.com/vbatts/tar-split/README.md b/vendor/github.com/vbatts/tar-split/README.md
new file mode 100644
index 000000000..4c544d823
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/README.md
@@ -0,0 +1,137 @@
+# tar-split
+
+[![Build Status](https://travis-ci.org/vbatts/tar-split.svg?branch=master)](https://travis-ci.org/vbatts/tar-split)
+
+Pristinely disassembling a tar archive, and stashing needed raw bytes and offsets to reassemble a validating original archive.
+
+## Docs
+
+Code API for libraries provided by `tar-split`:
+
+* https://godoc.org/github.com/vbatts/tar-split/tar/asm
+* https://godoc.org/github.com/vbatts/tar-split/tar/storage
+* https://godoc.org/github.com/vbatts/tar-split/archive/tar
+
+## Install
+
+The command line utilitiy is installable via:
+
+```bash
+go get github.com/vbatts/tar-split/cmd/tar-split
+```
+
+## Usage
+
+For cli usage, see its [README.md](cmd/tar-split/README.md).
+For the library see the [docs](#docs)
+
+## Demo
+
+### Basic disassembly and assembly
+
+This demonstrates the `tar-split` command and how to assemble a tar archive from the `tar-data.json.gz`
+
+
+![basic cmd demo thumbnail](https://i.ytimg.com/vi/vh5wyjIOBtc/2.jpg?time=1445027151805)
+[youtube video of basic command demo](https://youtu.be/vh5wyjIOBtc)
+
+### Docker layer preservation
+
+This demonstrates the tar-split integration for docker-1.8. Providing consistent tar archives for the image layer content.
+
+![docker tar-split demo](https://i.ytimg.com/vi_webp/vh5wyjIOBtc/default.webp)
+[youtube vide of docker layer checksums](https://youtu.be/tV_Dia8E8xw)
+
+## Caveat
+
+Eventually this should detect TARs that this is not possible with.
+
+For example stored sparse files that have "holes" in them, will be read as a
+contiguous file, though the archive contents may be recorded in sparse format.
+Therefore when adding the file payload to a reassembled tar, to achieve
+identical output, the file payload would need be precisely re-sparsified. This
+is not something I seek to fix imediately, but would rather have an alert that
+precise reassembly is not possible.
+(see more http://www.gnu.org/software/tar/manual/html_node/Sparse-Formats.html)
+
+
+Other caveat, while tar archives support having multiple file entries for the
+same path, we will not support this feature. If there are more than one entries
+with the same path, expect an err (like `ErrDuplicatePath`) or a resulting tar
+stream that does not validate your original checksum/signature.
+
+## Contract
+
+Do not break the API of stdlib `archive/tar` in our fork (ideally find an upstream mergeable solution).
+
+## Std Version
+
+The version of golang stdlib `archive/tar` is from go1.6
+It is minimally extended to expose the raw bytes of the TAR, rather than just the marshalled headers and file stream.
+
+
+## Design
+
+See the [design](concept/DESIGN.md).
+
+## Stored Metadata
+
+Since the raw bytes of the headers and padding are stored, you may be wondering
+what the size implications are. The headers are at least 512 bytes per
+file (sometimes more), at least 1024 null bytes on the end, and then various
+padding. This makes for a constant linear growth in the stored metadata, with a
+naive storage implementation.
+
+First we'll get an archive to work with. For repeatability, we'll make an
+archive from what you've just cloned:
+
+```bash
+git archive --format=tar -o tar-split.tar HEAD .
+```
+
+```bash
+$ go get github.com/vbatts/tar-split/cmd/tar-split
+$ tar-split checksize ./tar-split.tar
+inspecting "tar-split.tar" (size 210k)
+ -- number of files: 50
+ -- size of metadata uncompressed: 53k
+ -- size of gzip compressed metadata: 3k
+```
+
+So assuming you've managed the extraction of the archive yourself, for reuse of
+the file payloads from a relative path, then the only additional storage
+implications are as little as 3kb.
+
+But let's look at a larger archive, with many files.
+
+```bash
+$ ls -sh ./d.tar
+1.4G ./d.tar
+$ tar-split checksize ~/d.tar 
+inspecting "/home/vbatts/d.tar" (size 1420749k)
+ -- number of files: 38718
+ -- size of metadata uncompressed: 43261k
+ -- size of gzip compressed metadata: 2251k
+```
+
+Here, an archive with 38,718 files has a compressed footprint of about 2mb.
+
+Rolling the null bytes on the end of the archive, we will assume a
+bytes-per-file rate for the storage implications.
+
+| uncompressed | compressed |
+| :----------: | :--------: |
+| ~ 1kb per/file | 0.06kb per/file |
+
+
+## What's Next?
+
+* More implementations of storage Packer and Unpacker
+* More implementations of FileGetter and FilePutter
+* would be interesting to have an assembler stream that implements `io.Seeker`
+
+
+## License
+
+See [LICENSE](LICENSE)
+
diff --git a/vendor/github.com/vbatts/tar-split/archive/tar/common.go b/vendor/github.com/vbatts/tar-split/archive/tar/common.go
new file mode 100644
index 000000000..36f4e2398
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/archive/tar/common.go
@@ -0,0 +1,340 @@
+// 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.
+
+// Package tar 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
+//   http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html
+package tar
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"path"
+	"time"
+)
+
+const (
+	blockSize = 512
+
+	// Types
+	TypeReg           = '0'    // regular file
+	TypeRegA          = '\x00' // regular file
+	TypeLink          = '1'    // hard link
+	TypeSymlink       = '2'    // symbolic link
+	TypeChar          = '3'    // character device node
+	TypeBlock         = '4'    // block device node
+	TypeDir           = '5'    // directory
+	TypeFifo          = '6'    // fifo node
+	TypeCont          = '7'    // reserved
+	TypeXHeader       = 'x'    // extended header
+	TypeXGlobalHeader = 'g'    // global extended header
+	TypeGNULongName   = 'L'    // Next file has a long name
+	TypeGNULongLink   = 'K'    // Next file symlinks to a file w/ a long name
+	TypeGNUSparse     = 'S'    // sparse file
+)
+
+// A Header represents a single header in a tar archive.
+// Some fields may not be populated.
+type Header struct {
+	Name       string    // name of header file entry
+	Mode       int64     // permission and mode bits
+	Uid        int       // user id of owner
+	Gid        int       // group id of owner
+	Size       int64     // length in bytes
+	ModTime    time.Time // modified time
+	Typeflag   byte      // type of header entry
+	Linkname   string    // target name of link
+	Uname      string    // user name of owner
+	Gname      string    // group name of owner
+	Devmajor   int64     // major number of character or block device
+	Devminor   int64     // minor number of character or block device
+	AccessTime time.Time // access time
+	ChangeTime time.Time // status change time
+	Xattrs     map[string]string
+}
+
+// File name constants from the tar spec.
+const (
+	fileNameSize       = 100 // Maximum number of bytes in a standard tar name.
+	fileNamePrefixSize = 155 // Maximum number of ustar extension bytes.
+)
+
+// FileInfo returns an os.FileInfo for the Header.
+func (h *Header) FileInfo() os.FileInfo {
+	return headerFileInfo{h}
+}
+
+// headerFileInfo implements os.FileInfo.
+type headerFileInfo struct {
+	h *Header
+}
+
+func (fi headerFileInfo) Size() int64        { return fi.h.Size }
+func (fi headerFileInfo) IsDir() bool        { return fi.Mode().IsDir() }
+func (fi headerFileInfo) ModTime() time.Time { return fi.h.ModTime }
+func (fi headerFileInfo) Sys() interface{}   { return fi.h }
+
+// Name returns the base name of the file.
+func (fi headerFileInfo) Name() string {
+	if fi.IsDir() {
+		return path.Base(path.Clean(fi.h.Name))
+	}
+	return path.Base(fi.h.Name)
+}
+
+// Mode returns the permission and mode bits for the headerFileInfo.
+func (fi headerFileInfo) Mode() (mode os.FileMode) {
+	// Set file permission bits.
+	mode = os.FileMode(fi.h.Mode).Perm()
+
+	// Set setuid, setgid and sticky bits.
+	if fi.h.Mode&c_ISUID != 0 {
+		// setuid
+		mode |= os.ModeSetuid
+	}
+	if fi.h.Mode&c_ISGID != 0 {
+		// setgid
+		mode |= os.ModeSetgid
+	}
+	if fi.h.Mode&c_ISVTX != 0 {
+		// sticky
+		mode |= os.ModeSticky
+	}
+
+	// Set file mode bits.
+	// clear perm, setuid, setgid and sticky bits.
+	m := os.FileMode(fi.h.Mode) &^ 07777
+	if m == c_ISDIR {
+		// directory
+		mode |= os.ModeDir
+	}
+	if m == c_ISFIFO {
+		// named pipe (FIFO)
+		mode |= os.ModeNamedPipe
+	}
+	if m == c_ISLNK {
+		// symbolic link
+		mode |= os.ModeSymlink
+	}
+	if m == c_ISBLK {
+		// device file
+		mode |= os.ModeDevice
+	}
+	if m == c_ISCHR {
+		// Unix character device
+		mode |= os.ModeDevice
+		mode |= os.ModeCharDevice
+	}
+	if m == c_ISSOCK {
+		// Unix domain socket
+		mode |= os.ModeSocket
+	}
+
+	switch fi.h.Typeflag {
+	case TypeSymlink:
+		// symbolic link
+		mode |= os.ModeSymlink
+	case TypeChar:
+		// character device node
+		mode |= os.ModeDevice
+		mode |= os.ModeCharDevice
+	case TypeBlock:
+		// block device node
+		mode |= os.ModeDevice
+	case TypeDir:
+		// directory
+		mode |= os.ModeDir
+	case TypeFifo:
+		// fifo node
+		mode |= os.ModeNamedPipe
+	}
+
+	return mode
+}
+
+// sysStat, if non-nil, populates h from system-dependent fields of fi.
+var sysStat func(fi os.FileInfo, h *Header) error
+
+// Mode constants from the tar spec.
+const (
+	c_ISUID  = 04000   // Set uid
+	c_ISGID  = 02000   // Set gid
+	c_ISVTX  = 01000   // Save text (sticky bit)
+	c_ISDIR  = 040000  // Directory
+	c_ISFIFO = 010000  // FIFO
+	c_ISREG  = 0100000 // Regular file
+	c_ISLNK  = 0120000 // Symbolic link
+	c_ISBLK  = 060000  // Block special file
+	c_ISCHR  = 020000  // Character special file
+	c_ISSOCK = 0140000 // Socket
+)
+
+// Keywords for the PAX Extended Header
+const (
+	paxAtime    = "atime"
+	paxCharset  = "charset"
+	paxComment  = "comment"
+	paxCtime    = "ctime" // please note that ctime is not a valid pax header.
+	paxGid      = "gid"
+	paxGname    = "gname"
+	paxLinkpath = "linkpath"
+	paxMtime    = "mtime"
+	paxPath     = "path"
+	paxSize     = "size"
+	paxUid      = "uid"
+	paxUname    = "uname"
+	paxXattr    = "SCHILY.xattr."
+	paxNone     = ""
+)
+
+// FileInfoHeader creates a partially-populated Header from fi.
+// If fi describes a symlink, FileInfoHeader records link as the link target.
+// If fi describes a directory, a slash is appended to the name.
+// Because os.FileInfo's Name method returns only the base name of
+// the file it describes, it may be necessary to modify the Name field
+// of the returned header to provide the full path name of the file.
+func FileInfoHeader(fi os.FileInfo, link string) (*Header, error) {
+	if fi == nil {
+		return nil, errors.New("tar: FileInfo is nil")
+	}
+	fm := fi.Mode()
+	h := &Header{
+		Name:    fi.Name(),
+		ModTime: fi.ModTime(),
+		Mode:    int64(fm.Perm()), // or'd with c_IS* constants later
+	}
+	switch {
+	case fm.IsRegular():
+		h.Mode |= c_ISREG
+		h.Typeflag = TypeReg
+		h.Size = fi.Size()
+	case fi.IsDir():
+		h.Typeflag = TypeDir
+		h.Mode |= c_ISDIR
+		h.Name += "/"
+	case fm&os.ModeSymlink != 0:
+		h.Typeflag = TypeSymlink
+		h.Mode |= c_ISLNK
+		h.Linkname = link
+	case fm&os.ModeDevice != 0:
+		if fm&os.ModeCharDevice != 0 {
+			h.Mode |= c_ISCHR
+			h.Typeflag = TypeChar
+		} else {
+			h.Mode |= c_ISBLK
+			h.Typeflag = TypeBlock
+		}
+	case fm&os.ModeNamedPipe != 0:
+		h.Typeflag = TypeFifo
+		h.Mode |= c_ISFIFO
+	case fm&os.ModeSocket != 0:
+		h.Mode |= c_ISSOCK
+	default:
+		return nil, fmt.Errorf("archive/tar: unknown file mode %v", fm)
+	}
+	if fm&os.ModeSetuid != 0 {
+		h.Mode |= c_ISUID
+	}
+	if fm&os.ModeSetgid != 0 {
+		h.Mode |= c_ISGID
+	}
+	if fm&os.ModeSticky != 0 {
+		h.Mode |= c_ISVTX
+	}
+	// If possible, populate additional fields from OS-specific
+	// FileInfo fields.
+	if sys, ok := fi.Sys().(*Header); ok {
+		// This FileInfo came from a Header (not the OS). Use the
+		// original Header to populate all remaining fields.
+		h.Uid = sys.Uid
+		h.Gid = sys.Gid
+		h.Uname = sys.Uname
+		h.Gname = sys.Gname
+		h.AccessTime = sys.AccessTime
+		h.ChangeTime = sys.ChangeTime
+		if sys.Xattrs != nil {
+			h.Xattrs = make(map[string]string)
+			for k, v := range sys.Xattrs {
+				h.Xattrs[k] = v
+			}
+		}
+		if sys.Typeflag == TypeLink {
+			// hard link
+			h.Typeflag = TypeLink
+			h.Size = 0
+			h.Linkname = sys.Linkname
+		}
+	}
+	if sysStat != nil {
+		return h, sysStat(fi, h)
+	}
+	return h, nil
+}
+
+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
+}
+
+func isASCII(s string) bool {
+	for _, c := range s {
+		if c >= 0x80 {
+			return false
+		}
+	}
+	return true
+}
+
+func toASCII(s string) string {
+	if isASCII(s) {
+		return s
+	}
+	var buf bytes.Buffer
+	for _, c := range s {
+		if c < 0x80 {
+			buf.WriteByte(byte(c))
+		}
+	}
+	return buf.String()
+}
+
+// isHeaderOnlyType checks if the given type flag is of the type that has no
+// data section even if a size is specified.
+func isHeaderOnlyType(flag byte) bool {
+	switch flag {
+	case TypeLink, TypeSymlink, TypeChar, TypeBlock, TypeDir, TypeFifo:
+		return true
+	default:
+		return false
+	}
+}
diff --git a/vendor/github.com/vbatts/tar-split/archive/tar/reader.go b/vendor/github.com/vbatts/tar-split/archive/tar/reader.go
new file mode 100644
index 000000000..adf32122e
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/archive/tar/reader.go
@@ -0,0 +1,1064 @@
+// 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.
+
+package tar
+
+// TODO(dsymonds):
+//   - pax extensions
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"io/ioutil"
+	"math"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var (
+	ErrHeader = errors.New("archive/tar: invalid tar header")
+)
+
+const maxNanoSecondIntSize = 9
+
+// A Reader provides sequential access to the contents of a tar archive.
+// A tar archive consists of a sequence of files.
+// The Next method advances to the next file in the archive (including the first),
+// and then it can be treated as an io.Reader to access the file's data.
+type Reader struct {
+	r       io.Reader
+	err     error
+	pad     int64           // amount of padding (ignored) after current file entry
+	curr    numBytesReader  // reader for current file entry
+	hdrBuff [blockSize]byte // buffer to use in readHeader
+
+	RawAccounting bool          // Whether to enable the access needed to reassemble the tar from raw bytes. Some performance/memory hit for this.
+	rawBytes      *bytes.Buffer // last raw bits
+}
+
+type parser struct {
+	err error // Last error seen
+}
+
+// RawBytes accesses the raw bytes of the archive, apart from the file payload itself.
+// This includes the header and padding.
+//
+// This call resets the current rawbytes buffer
+//
+// Only when RawAccounting is enabled, otherwise this returns nil
+func (tr *Reader) RawBytes() []byte {
+	if !tr.RawAccounting {
+		return nil
+	}
+	if tr.rawBytes == nil {
+		tr.rawBytes = bytes.NewBuffer(nil)
+	}
+	// if we've read them, then flush them.
+	defer tr.rawBytes.Reset()
+	return tr.rawBytes.Bytes()
+}
+
+// A numBytesReader is an io.Reader with a numBytes method, returning the number
+// of bytes remaining in the underlying encoded data.
+type numBytesReader interface {
+	io.Reader
+	numBytes() int64
+}
+
+// A regFileReader is a numBytesReader for reading file data from a tar archive.
+type regFileReader struct {
+	r  io.Reader // underlying reader
+	nb int64     // number of unread bytes for current file entry
+}
+
+// A sparseFileReader is a numBytesReader for reading sparse file data from a
+// tar archive.
+type sparseFileReader struct {
+	rfr   numBytesReader // Reads the sparse-encoded file data
+	sp    []sparseEntry  // The sparse map for the file
+	pos   int64          // Keeps track of file position
+	total int64          // Total size of the file
+}
+
+// A sparseEntry holds a single entry in a sparse file's sparse map.
+//
+// Sparse files are represented using a series of sparseEntrys.
+// Despite the name, a sparseEntry represents an actual data fragment that
+// references data found in the underlying archive stream. All regions not
+// covered by a sparseEntry are logically filled with zeros.
+//
+// For example, if the underlying raw file contains the 10-byte data:
+//	var compactData = "abcdefgh"
+//
+// And the sparse map has the following entries:
+//	var sp = []sparseEntry{
+//		{offset: 2,  numBytes: 5} // Data fragment for [2..7]
+//		{offset: 18, numBytes: 3} // Data fragment for [18..21]
+//	}
+//
+// Then the content of the resulting sparse file with a "real" size of 25 is:
+//	var sparseData = "\x00"*2 + "abcde" + "\x00"*11 + "fgh" + "\x00"*4
+type sparseEntry struct {
+	offset   int64 // Starting position of the fragment
+	numBytes int64 // Length of the fragment
+}
+
+// Keywords for GNU sparse files in a PAX extended header
+const (
+	paxGNUSparseNumBlocks = "GNU.sparse.numblocks"
+	paxGNUSparseOffset    = "GNU.sparse.offset"
+	paxGNUSparseNumBytes  = "GNU.sparse.numbytes"
+	paxGNUSparseMap       = "GNU.sparse.map"
+	paxGNUSparseName      = "GNU.sparse.name"
+	paxGNUSparseMajor     = "GNU.sparse.major"
+	paxGNUSparseMinor     = "GNU.sparse.minor"
+	paxGNUSparseSize      = "GNU.sparse.size"
+	paxGNUSparseRealSize  = "GNU.sparse.realsize"
+)
+
+// Keywords for old GNU sparse headers
+const (
+	oldGNUSparseMainHeaderOffset               = 386
+	oldGNUSparseMainHeaderIsExtendedOffset     = 482
+	oldGNUSparseMainHeaderNumEntries           = 4
+	oldGNUSparseExtendedHeaderIsExtendedOffset = 504
+	oldGNUSparseExtendedHeaderNumEntries       = 21
+	oldGNUSparseOffsetSize                     = 12
+	oldGNUSparseNumBytesSize                   = 12
+)
+
+// NewReader creates a new Reader reading from r.
+func NewReader(r io.Reader) *Reader { return &Reader{r: r} }
+
+// Next advances to the next entry in the tar archive.
+//
+// io.EOF is returned at the end of the input.
+func (tr *Reader) Next() (*Header, error) {
+	if tr.RawAccounting {
+		if tr.rawBytes == nil {
+			tr.rawBytes = bytes.NewBuffer(nil)
+		} else {
+			tr.rawBytes.Reset()
+		}
+	}
+
+	if tr.err != nil {
+		return nil, tr.err
+	}
+
+	var hdr *Header
+	var extHdrs map[string]string
+
+	// Externally, Next iterates through the tar archive as if it is a series of
+	// files. Internally, the tar format often uses fake "files" to add meta
+	// data that describes the next file. These meta data "files" should not
+	// normally be visible to the outside. As such, this loop iterates through
+	// one or more "header files" until it finds a "normal file".
+loop:
+	for {
+		tr.err = tr.skipUnread()
+		if tr.err != nil {
+			return nil, tr.err
+		}
+
+		hdr = tr.readHeader()
+		if tr.err != nil {
+			return nil, tr.err
+		}
+		// Check for PAX/GNU special headers and files.
+		switch hdr.Typeflag {
+		case TypeXHeader:
+			extHdrs, tr.err = parsePAX(tr)
+			if tr.err != nil {
+				return nil, tr.err
+			}
+			continue loop // This is a meta header affecting the next header
+		case TypeGNULongName, TypeGNULongLink:
+			var realname []byte
+			realname, tr.err = ioutil.ReadAll(tr)
+			if tr.err != nil {
+				return nil, tr.err
+			}
+
+			if tr.RawAccounting {
+				if _, tr.err = tr.rawBytes.Write(realname); tr.err != nil {
+					return nil, tr.err
+				}
+			}
+
+			// Convert GNU extensions to use PAX headers.
+			if extHdrs == nil {
+				extHdrs = make(map[string]string)
+			}
+			var p parser
+			switch hdr.Typeflag {
+			case TypeGNULongName:
+				extHdrs[paxPath] = p.parseString(realname)
+			case TypeGNULongLink:
+				extHdrs[paxLinkpath] = p.parseString(realname)
+			}
+			if p.err != nil {
+				tr.err = p.err
+				return nil, tr.err
+			}
+			continue loop // This is a meta header affecting the next header
+		default:
+			mergePAX(hdr, extHdrs)
+
+			// Check for a PAX format sparse file
+			sp, err := tr.checkForGNUSparsePAXHeaders(hdr, extHdrs)
+			if err != nil {
+				tr.err = err
+				return nil, err
+			}
+			if sp != nil {
+				// Current file is a PAX format GNU sparse file.
+				// Set the current file reader to a sparse file reader.
+				tr.curr, tr.err = newSparseFileReader(tr.curr, sp, hdr.Size)
+				if tr.err != nil {
+					return nil, tr.err
+				}
+			}
+			break loop // This is a file, so stop
+		}
+	}
+	return hdr, nil
+}
+
+// checkForGNUSparsePAXHeaders checks the PAX headers for GNU sparse headers. If they are found, then
+// this function reads the sparse map and returns it. Unknown sparse formats are ignored, causing the file to
+// be treated as a regular file.
+func (tr *Reader) checkForGNUSparsePAXHeaders(hdr *Header, headers map[string]string) ([]sparseEntry, error) {
+	var sparseFormat string
+
+	// Check for sparse format indicators
+	major, majorOk := headers[paxGNUSparseMajor]
+	minor, minorOk := headers[paxGNUSparseMinor]
+	sparseName, sparseNameOk := headers[paxGNUSparseName]
+	_, sparseMapOk := headers[paxGNUSparseMap]
+	sparseSize, sparseSizeOk := headers[paxGNUSparseSize]
+	sparseRealSize, sparseRealSizeOk := headers[paxGNUSparseRealSize]
+
+	// Identify which, if any, sparse format applies from which PAX headers are set
+	if majorOk && minorOk {
+		sparseFormat = major + "." + minor
+	} else if sparseNameOk && sparseMapOk {
+		sparseFormat = "0.1"
+	} else if sparseSizeOk {
+		sparseFormat = "0.0"
+	} else {
+		// Not a PAX format GNU sparse file.
+		return nil, nil
+	}
+
+	// Check for unknown sparse format
+	if sparseFormat != "0.0" && sparseFormat != "0.1" && sparseFormat != "1.0" {
+		return nil, nil
+	}
+
+	// Update hdr from GNU sparse PAX headers
+	if sparseNameOk {
+		hdr.Name = sparseName
+	}
+	if sparseSizeOk {
+		realSize, err := strconv.ParseInt(sparseSize, 10, 0)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		hdr.Size = realSize
+	} else if sparseRealSizeOk {
+		realSize, err := strconv.ParseInt(sparseRealSize, 10, 0)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		hdr.Size = realSize
+	}
+
+	// Set up the sparse map, according to the particular sparse format in use
+	var sp []sparseEntry
+	var err error
+	switch sparseFormat {
+	case "0.0", "0.1":
+		sp, err = readGNUSparseMap0x1(headers)
+	case "1.0":
+		sp, err = readGNUSparseMap1x0(tr.curr)
+	}
+	return sp, err
+}
+
+// mergePAX merges well known headers according to PAX standard.
+// In general headers with the same name as those found
+// in the header struct overwrite those found in the header
+// struct with higher precision or longer values. Esp. useful
+// for name and linkname fields.
+func mergePAX(hdr *Header, headers map[string]string) error {
+	for k, v := range headers {
+		switch k {
+		case paxPath:
+			hdr.Name = v
+		case paxLinkpath:
+			hdr.Linkname = v
+		case paxGname:
+			hdr.Gname = v
+		case paxUname:
+			hdr.Uname = v
+		case paxUid:
+			uid, err := strconv.ParseInt(v, 10, 0)
+			if err != nil {
+				return err
+			}
+			hdr.Uid = int(uid)
+		case paxGid:
+			gid, err := strconv.ParseInt(v, 10, 0)
+			if err != nil {
+				return err
+			}
+			hdr.Gid = int(gid)
+		case paxAtime:
+			t, err := parsePAXTime(v)
+			if err != nil {
+				return err
+			}
+			hdr.AccessTime = t
+		case paxMtime:
+			t, err := parsePAXTime(v)
+			if err != nil {
+				return err
+			}
+			hdr.ModTime = t
+		case paxCtime:
+			t, err := parsePAXTime(v)
+			if err != nil {
+				return err
+			}
+			hdr.ChangeTime = t
+		case paxSize:
+			size, err := strconv.ParseInt(v, 10, 0)
+			if err != nil {
+				return err
+			}
+			hdr.Size = int64(size)
+		default:
+			if strings.HasPrefix(k, paxXattr) {
+				if hdr.Xattrs == nil {
+					hdr.Xattrs = make(map[string]string)
+				}
+				hdr.Xattrs[k[len(paxXattr):]] = v
+			}
+		}
+	}
+	return nil
+}
+
+// parsePAXTime takes a string of the form %d.%d as described in
+// the PAX specification.
+func parsePAXTime(t string) (time.Time, error) {
+	buf := []byte(t)
+	pos := bytes.IndexByte(buf, '.')
+	var seconds, nanoseconds int64
+	var err error
+	if pos == -1 {
+		seconds, err = strconv.ParseInt(t, 10, 0)
+		if err != nil {
+			return time.Time{}, err
+		}
+	} else {
+		seconds, err = strconv.ParseInt(string(buf[:pos]), 10, 0)
+		if err != nil {
+			return time.Time{}, err
+		}
+		nano_buf := string(buf[pos+1:])
+		// Pad as needed before converting to a decimal.
+		// For example .030 -> .030000000 -> 30000000 nanoseconds
+		if len(nano_buf) < maxNanoSecondIntSize {
+			// Right pad
+			nano_buf += strings.Repeat("0", maxNanoSecondIntSize-len(nano_buf))
+		} else if len(nano_buf) > maxNanoSecondIntSize {
+			// Right truncate
+			nano_buf = nano_buf[:maxNanoSecondIntSize]
+		}
+		nanoseconds, err = strconv.ParseInt(string(nano_buf), 10, 0)
+		if err != nil {
+			return time.Time{}, err
+		}
+	}
+	ts := time.Unix(seconds, nanoseconds)
+	return ts, nil
+}
+
+// parsePAX parses PAX headers.
+// If an extended header (type 'x') is invalid, ErrHeader is returned
+func parsePAX(r io.Reader) (map[string]string, error) {
+	buf, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, err
+	}
+	// leaving this function for io.Reader makes it more testable
+	if tr, ok := r.(*Reader); ok && tr.RawAccounting {
+		if _, err = tr.rawBytes.Write(buf); err != nil {
+			return nil, err
+		}
+	}
+	sbuf := string(buf)
+
+	// For GNU PAX sparse format 0.0 support.
+	// This function transforms the sparse format 0.0 headers into sparse format 0.1 headers.
+	var sparseMap bytes.Buffer
+
+	headers := make(map[string]string)
+	// Each record is constructed as
+	//     "%d %s=%s\n", length, keyword, value
+	for len(sbuf) > 0 {
+		key, value, residual, err := parsePAXRecord(sbuf)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		sbuf = residual
+
+		keyStr := string(key)
+		if keyStr == paxGNUSparseOffset || keyStr == paxGNUSparseNumBytes {
+			// GNU sparse format 0.0 special key. Write to sparseMap instead of using the headers map.
+			sparseMap.WriteString(value)
+			sparseMap.Write([]byte{','})
+		} else {
+			// Normal key. Set the value in the headers map.
+			headers[keyStr] = string(value)
+		}
+	}
+	if sparseMap.Len() != 0 {
+		// Add sparse info to headers, chopping off the extra comma
+		sparseMap.Truncate(sparseMap.Len() - 1)
+		headers[paxGNUSparseMap] = sparseMap.String()
+	}
+	return headers, nil
+}
+
+// parsePAXRecord parses the input PAX record string into a key-value pair.
+// If parsing is successful, it will slice off the currently read record and
+// return the remainder as r.
+//
+// A PAX record is of the following form:
+//	"%d %s=%s\n" % (size, key, value)
+func parsePAXRecord(s string) (k, v, r string, err error) {
+	// The size field ends at the first space.
+	sp := strings.IndexByte(s, ' ')
+	if sp == -1 {
+		return "", "", s, ErrHeader
+	}
+
+	// Parse the first token as a decimal integer.
+	n, perr := strconv.ParseInt(s[:sp], 10, 0) // Intentionally parse as native int
+	if perr != nil || n < 5 || int64(len(s)) < n {
+		return "", "", s, ErrHeader
+	}
+
+	// Extract everything between the space and the final newline.
+	rec, nl, rem := s[sp+1:n-1], s[n-1:n], s[n:]
+	if nl != "\n" {
+		return "", "", s, ErrHeader
+	}
+
+	// The first equals separates the key from the value.
+	eq := strings.IndexByte(rec, '=')
+	if eq == -1 {
+		return "", "", s, ErrHeader
+	}
+	return rec[:eq], rec[eq+1:], rem, nil
+}
+
+// parseString parses bytes as a NUL-terminated C-style string.
+// If a NUL byte is not found then the whole slice is returned as a string.
+func (*parser) parseString(b []byte) string {
+	n := 0
+	for n < len(b) && b[n] != 0 {
+		n++
+	}
+	return string(b[0:n])
+}
+
+// parseNumeric parses the input as being encoded in either base-256 or octal.
+// This function may return negative numbers.
+// If parsing fails or an integer overflow occurs, err will be set.
+func (p *parser) parseNumeric(b []byte) int64 {
+	// Check for base-256 (binary) format first.
+	// If the first bit is set, then all following bits constitute a two's
+	// complement encoded number in big-endian byte order.
+	if len(b) > 0 && b[0]&0x80 != 0 {
+		// Handling negative numbers relies on the following identity:
+		//	-a-1 == ^a
+		//
+		// If the number is negative, we use an inversion mask to invert the
+		// data bytes and treat the value as an unsigned number.
+		var inv byte // 0x00 if positive or zero, 0xff if negative
+		if b[0]&0x40 != 0 {
+			inv = 0xff
+		}
+
+		var x uint64
+		for i, c := range b {
+			c ^= inv // Inverts c only if inv is 0xff, otherwise does nothing
+			if i == 0 {
+				c &= 0x7f // Ignore signal bit in first byte
+			}
+			if (x >> 56) > 0 {
+				p.err = ErrHeader // Integer overflow
+				return 0
+			}
+			x = x<<8 | uint64(c)
+		}
+		if (x >> 63) > 0 {
+			p.err = ErrHeader // Integer overflow
+			return 0
+		}
+		if inv == 0xff {
+			return ^int64(x)
+		}
+		return int64(x)
+	}
+
+	// Normal case is base-8 (octal) format.
+	return p.parseOctal(b)
+}
+
+func (p *parser) parseOctal(b []byte) int64 {
+	// Because unused fields are filled with NULs, we need
+	// to skip leading NULs. Fields may also be padded with
+	// spaces or NULs.
+	// So we remove leading and trailing NULs and spaces to
+	// be sure.
+	b = bytes.Trim(b, " \x00")
+
+	if len(b) == 0 {
+		return 0
+	}
+	x, perr := strconv.ParseUint(p.parseString(b), 8, 64)
+	if perr != nil {
+		p.err = ErrHeader
+	}
+	return int64(x)
+}
+
+// skipUnread skips any unread bytes in the existing file entry, as well as any
+// alignment padding. It returns io.ErrUnexpectedEOF if any io.EOF is
+// encountered in the data portion; it is okay to hit io.EOF in the padding.
+//
+// Note that this function still works properly even when sparse files are being
+// used since numBytes returns the bytes remaining in the underlying io.Reader.
+func (tr *Reader) skipUnread() error {
+	dataSkip := tr.numBytes()      // Number of data bytes to skip
+	totalSkip := dataSkip + tr.pad // Total number of bytes to skip
+	tr.curr, tr.pad = nil, 0
+	if tr.RawAccounting {
+		_, tr.err = io.CopyN(tr.rawBytes, tr.r, totalSkip)
+		return tr.err
+	}
+	// If possible, Seek to the last byte before the end of the data section.
+	// Do this because Seek is often lazy about reporting errors; this will mask
+	// the fact that the tar stream may be truncated. We can rely on the
+	// io.CopyN done shortly afterwards to trigger any IO errors.
+	var seekSkipped int64 // Number of bytes skipped via Seek
+	if sr, ok := tr.r.(io.Seeker); ok && dataSkip > 1 {
+		// Not all io.Seeker can actually Seek. For example, os.Stdin implements
+		// io.Seeker, but calling Seek always returns an error and performs
+		// no action. Thus, we try an innocent seek to the current position
+		// to see if Seek is really supported.
+		pos1, err := sr.Seek(0, os.SEEK_CUR)
+		if err == nil {
+			// Seek seems supported, so perform the real Seek.
+			pos2, err := sr.Seek(dataSkip-1, os.SEEK_CUR)
+			if err != nil {
+				tr.err = err
+				return tr.err
+			}
+			seekSkipped = pos2 - pos1
+		}
+	}
+
+	var copySkipped int64 // Number of bytes skipped via CopyN
+	copySkipped, tr.err = io.CopyN(ioutil.Discard, tr.r, totalSkip-seekSkipped)
+	if tr.err == io.EOF && seekSkipped+copySkipped < dataSkip {
+		tr.err = io.ErrUnexpectedEOF
+	}
+	return tr.err
+}
+
+func (tr *Reader) verifyChecksum(header []byte) bool {
+	if tr.err != nil {
+		return false
+	}
+
+	var p parser
+	given := p.parseOctal(header[148:156])
+	unsigned, signed := checksum(header)
+	return p.err == nil && (given == unsigned || given == signed)
+}
+
+// readHeader reads the next block header and assumes that the underlying reader
+// is already aligned to a block boundary.
+//
+// The err will be set to io.EOF only when one of the following occurs:
+//	* Exactly 0 bytes are read and EOF is hit.
+//	* Exactly 1 block of zeros is read and EOF is hit.
+//	* At least 2 blocks of zeros are read.
+func (tr *Reader) readHeader() *Header {
+	header := tr.hdrBuff[:]
+	copy(header, zeroBlock)
+
+	if n, err := io.ReadFull(tr.r, header); err != nil {
+		tr.err = err
+		// because it could read some of the block, but reach EOF first
+		if tr.err == io.EOF && tr.RawAccounting {
+			if _, err := tr.rawBytes.Write(header[:n]); err != nil {
+				tr.err = err
+			}
+		}
+		return nil // io.EOF is okay here
+	}
+	if tr.RawAccounting {
+		if _, tr.err = tr.rawBytes.Write(header); tr.err != nil {
+			return nil
+		}
+	}
+
+	// Two blocks of zero bytes marks the end of the archive.
+	if bytes.Equal(header, zeroBlock[0:blockSize]) {
+		if n, err := io.ReadFull(tr.r, header); err != nil {
+			tr.err = err
+			// because it could read some of the block, but reach EOF first
+			if tr.err == io.EOF && tr.RawAccounting {
+				if _, err := tr.rawBytes.Write(header[:n]); err != nil {
+					tr.err = err
+				}
+			}
+			return nil // io.EOF is okay here
+		}
+		if tr.RawAccounting {
+			if _, tr.err = tr.rawBytes.Write(header); tr.err != nil {
+				return nil
+			}
+		}
+		if bytes.Equal(header, zeroBlock[0:blockSize]) {
+			tr.err = io.EOF
+		} else {
+			tr.err = ErrHeader // zero block and then non-zero block
+		}
+		return nil
+	}
+
+	if !tr.verifyChecksum(header) {
+		tr.err = ErrHeader
+		return nil
+	}
+
+	// Unpack
+	var p parser
+	hdr := new(Header)
+	s := slicer(header)
+
+	hdr.Name = p.parseString(s.next(100))
+	hdr.Mode = p.parseNumeric(s.next(8))
+	hdr.Uid = int(p.parseNumeric(s.next(8)))
+	hdr.Gid = int(p.parseNumeric(s.next(8)))
+	hdr.Size = p.parseNumeric(s.next(12))
+	hdr.ModTime = time.Unix(p.parseNumeric(s.next(12)), 0)
+	s.next(8) // chksum
+	hdr.Typeflag = s.next(1)[0]
+	hdr.Linkname = p.parseString(s.next(100))
+
+	// The remainder of the header depends on the value of magic.
+	// The original (v7) version of tar had no explicit magic field,
+	// so its magic bytes, like the rest of the block, are NULs.
+	magic := string(s.next(8)) // contains version field as well.
+	var format string
+	switch {
+	case magic[:6] == "ustar\x00": // POSIX tar (1003.1-1988)
+		if string(header[508:512]) == "tar\x00" {
+			format = "star"
+		} else {
+			format = "posix"
+		}
+	case magic == "ustar  \x00": // old GNU tar
+		format = "gnu"
+	}
+
+	switch format {
+	case "posix", "gnu", "star":
+		hdr.Uname = p.parseString(s.next(32))
+		hdr.Gname = p.parseString(s.next(32))
+		devmajor := s.next(8)
+		devminor := s.next(8)
+		if hdr.Typeflag == TypeChar || hdr.Typeflag == TypeBlock {
+			hdr.Devmajor = p.parseNumeric(devmajor)
+			hdr.Devminor = p.parseNumeric(devminor)
+		}
+		var prefix string
+		switch format {
+		case "posix", "gnu":
+			prefix = p.parseString(s.next(155))
+		case "star":
+			prefix = p.parseString(s.next(131))
+			hdr.AccessTime = time.Unix(p.parseNumeric(s.next(12)), 0)
+			hdr.ChangeTime = time.Unix(p.parseNumeric(s.next(12)), 0)
+		}
+		if len(prefix) > 0 {
+			hdr.Name = prefix + "/" + hdr.Name
+		}
+	}
+
+	if p.err != nil {
+		tr.err = p.err
+		return nil
+	}
+
+	nb := hdr.Size
+	if isHeaderOnlyType(hdr.Typeflag) {
+		nb = 0
+	}
+	if nb < 0 {
+		tr.err = ErrHeader
+		return nil
+	}
+
+	// Set the current file reader.
+	tr.pad = -nb & (blockSize - 1) // blockSize is a power of two
+	tr.curr = &regFileReader{r: tr.r, nb: nb}
+
+	// Check for old GNU sparse format entry.
+	if hdr.Typeflag == TypeGNUSparse {
+		// Get the real size of the file.
+		hdr.Size = p.parseNumeric(header[483:495])
+		if p.err != nil {
+			tr.err = p.err
+			return nil
+		}
+
+		// Read the sparse map.
+		sp := tr.readOldGNUSparseMap(header)
+		if tr.err != nil {
+			return nil
+		}
+
+		// Current file is a GNU sparse file. Update the current file reader.
+		tr.curr, tr.err = newSparseFileReader(tr.curr, sp, hdr.Size)
+		if tr.err != nil {
+			return nil
+		}
+	}
+
+	return hdr
+}
+
+// readOldGNUSparseMap reads the sparse map as stored in the old GNU sparse format.
+// The sparse map is stored in the tar header if it's small enough. If it's larger than four entries,
+// then one or more extension headers are used to store the rest of the sparse map.
+func (tr *Reader) readOldGNUSparseMap(header []byte) []sparseEntry {
+	var p parser
+	isExtended := header[oldGNUSparseMainHeaderIsExtendedOffset] != 0
+	spCap := oldGNUSparseMainHeaderNumEntries
+	if isExtended {
+		spCap += oldGNUSparseExtendedHeaderNumEntries
+	}
+	sp := make([]sparseEntry, 0, spCap)
+	s := slicer(header[oldGNUSparseMainHeaderOffset:])
+
+	// Read the four entries from the main tar header
+	for i := 0; i < oldGNUSparseMainHeaderNumEntries; i++ {
+		offset := p.parseNumeric(s.next(oldGNUSparseOffsetSize))
+		numBytes := p.parseNumeric(s.next(oldGNUSparseNumBytesSize))
+		if p.err != nil {
+			tr.err = p.err
+			return nil
+		}
+		if offset == 0 && numBytes == 0 {
+			break
+		}
+		sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
+	}
+
+	for isExtended {
+		// There are more entries. Read an extension header and parse its entries.
+		sparseHeader := make([]byte, blockSize)
+		if _, tr.err = io.ReadFull(tr.r, sparseHeader); tr.err != nil {
+			return nil
+		}
+		if tr.RawAccounting {
+			if _, tr.err = tr.rawBytes.Write(sparseHeader); tr.err != nil {
+				return nil
+			}
+		}
+
+		isExtended = sparseHeader[oldGNUSparseExtendedHeaderIsExtendedOffset] != 0
+		s = slicer(sparseHeader)
+		for i := 0; i < oldGNUSparseExtendedHeaderNumEntries; i++ {
+			offset := p.parseNumeric(s.next(oldGNUSparseOffsetSize))
+			numBytes := p.parseNumeric(s.next(oldGNUSparseNumBytesSize))
+			if p.err != nil {
+				tr.err = p.err
+				return nil
+			}
+			if offset == 0 && numBytes == 0 {
+				break
+			}
+			sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
+		}
+	}
+	return sp
+}
+
+// readGNUSparseMap1x0 reads the sparse map as stored in GNU's PAX sparse format
+// version 1.0. The format of the sparse map consists of a series of
+// newline-terminated numeric fields. The first field is the number of entries
+// and is always present. Following this are the entries, consisting of two
+// fields (offset, numBytes). This function must stop reading at the end
+// boundary of the block containing the last newline.
+//
+// Note that the GNU manual says that numeric values should be encoded in octal
+// format. However, the GNU tar utility itself outputs these values in decimal.
+// As such, this library treats values as being encoded in decimal.
+func readGNUSparseMap1x0(r io.Reader) ([]sparseEntry, error) {
+	var cntNewline int64
+	var buf bytes.Buffer
+	var blk = make([]byte, blockSize)
+
+	// feedTokens copies data in numBlock chunks from r into buf until there are
+	// at least cnt newlines in buf. It will not read more blocks than needed.
+	var feedTokens = func(cnt int64) error {
+		for cntNewline < cnt {
+			if _, err := io.ReadFull(r, blk); err != nil {
+				if err == io.EOF {
+					err = io.ErrUnexpectedEOF
+				}
+				return err
+			}
+			buf.Write(blk)
+			for _, c := range blk {
+				if c == '\n' {
+					cntNewline++
+				}
+			}
+		}
+		return nil
+	}
+
+	// nextToken gets the next token delimited by a newline. This assumes that
+	// at least one newline exists in the buffer.
+	var nextToken = func() string {
+		cntNewline--
+		tok, _ := buf.ReadString('\n')
+		return tok[:len(tok)-1] // Cut off newline
+	}
+
+	// Parse for the number of entries.
+	// Use integer overflow resistant math to check this.
+	if err := feedTokens(1); err != nil {
+		return nil, err
+	}
+	numEntries, err := strconv.ParseInt(nextToken(), 10, 0) // Intentionally parse as native int
+	if err != nil || numEntries < 0 || int(2*numEntries) < int(numEntries) {
+		return nil, ErrHeader
+	}
+
+	// Parse for all member entries.
+	// numEntries is trusted after this since a potential attacker must have
+	// committed resources proportional to what this library used.
+	if err := feedTokens(2 * numEntries); err != nil {
+		return nil, err
+	}
+	sp := make([]sparseEntry, 0, numEntries)
+	for i := int64(0); i < numEntries; i++ {
+		offset, err := strconv.ParseInt(nextToken(), 10, 64)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		numBytes, err := strconv.ParseInt(nextToken(), 10, 64)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
+	}
+	return sp, nil
+}
+
+// readGNUSparseMap0x1 reads the sparse map as stored in GNU's PAX sparse format
+// version 0.1. The sparse map is stored in the PAX headers.
+func readGNUSparseMap0x1(extHdrs map[string]string) ([]sparseEntry, error) {
+	// Get number of entries.
+	// Use integer overflow resistant math to check this.
+	numEntriesStr := extHdrs[paxGNUSparseNumBlocks]
+	numEntries, err := strconv.ParseInt(numEntriesStr, 10, 0) // Intentionally parse as native int
+	if err != nil || numEntries < 0 || int(2*numEntries) < int(numEntries) {
+		return nil, ErrHeader
+	}
+
+	// There should be two numbers in sparseMap for each entry.
+	sparseMap := strings.Split(extHdrs[paxGNUSparseMap], ",")
+	if int64(len(sparseMap)) != 2*numEntries {
+		return nil, ErrHeader
+	}
+
+	// Loop through the entries in the sparse map.
+	// numEntries is trusted now.
+	sp := make([]sparseEntry, 0, numEntries)
+	for i := int64(0); i < numEntries; i++ {
+		offset, err := strconv.ParseInt(sparseMap[2*i], 10, 64)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		numBytes, err := strconv.ParseInt(sparseMap[2*i+1], 10, 64)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
+	}
+	return sp, nil
+}
+
+// numBytes returns the number of bytes left to read in the current file's entry
+// in the tar archive, or 0 if there is no current file.
+func (tr *Reader) numBytes() int64 {
+	if tr.curr == nil {
+		// No current file, so no bytes
+		return 0
+	}
+	return tr.curr.numBytes()
+}
+
+// Read reads from the current entry in the tar archive.
+// It returns 0, io.EOF when it reaches the end of that entry,
+// until Next is called to advance to the next entry.
+//
+// Calling Read on special types like TypeLink, TypeSymLink, TypeChar,
+// TypeBlock, TypeDir, and TypeFifo returns 0, io.EOF regardless of what
+// the Header.Size claims.
+func (tr *Reader) Read(b []byte) (n int, err error) {
+	if tr.err != nil {
+		return 0, tr.err
+	}
+	if tr.curr == nil {
+		return 0, io.EOF
+	}
+
+	n, err = tr.curr.Read(b)
+	if err != nil && err != io.EOF {
+		tr.err = err
+	}
+	return
+}
+
+func (rfr *regFileReader) Read(b []byte) (n int, err error) {
+	if rfr.nb == 0 {
+		// file consumed
+		return 0, io.EOF
+	}
+	if int64(len(b)) > rfr.nb {
+		b = b[0:rfr.nb]
+	}
+	n, err = rfr.r.Read(b)
+	rfr.nb -= int64(n)
+
+	if err == io.EOF && rfr.nb > 0 {
+		err = io.ErrUnexpectedEOF
+	}
+	return
+}
+
+// numBytes returns the number of bytes left to read in the file's data in the tar archive.
+func (rfr *regFileReader) numBytes() int64 {
+	return rfr.nb
+}
+
+// newSparseFileReader creates a new sparseFileReader, but validates all of the
+// sparse entries before doing so.
+func newSparseFileReader(rfr numBytesReader, sp []sparseEntry, total int64) (*sparseFileReader, error) {
+	if total < 0 {
+		return nil, ErrHeader // Total size cannot be negative
+	}
+
+	// Validate all sparse entries. These are the same checks as performed by
+	// the BSD tar utility.
+	for i, s := range sp {
+		switch {
+		case s.offset < 0 || s.numBytes < 0:
+			return nil, ErrHeader // Negative values are never okay
+		case s.offset > math.MaxInt64-s.numBytes:
+			return nil, ErrHeader // Integer overflow with large length
+		case s.offset+s.numBytes > total:
+			return nil, ErrHeader // Region extends beyond the "real" size
+		case i > 0 && sp[i-1].offset+sp[i-1].numBytes > s.offset:
+			return nil, ErrHeader // Regions can't overlap and must be in order
+		}
+	}
+	return &sparseFileReader{rfr: rfr, sp: sp, total: total}, nil
+}
+
+// readHole reads a sparse hole ending at endOffset.
+func (sfr *sparseFileReader) readHole(b []byte, endOffset int64) int {
+	n64 := endOffset - sfr.pos
+	if n64 > int64(len(b)) {
+		n64 = int64(len(b))
+	}
+	n := int(n64)
+	for i := 0; i < n; i++ {
+		b[i] = 0
+	}
+	sfr.pos += n64
+	return n
+}
+
+// Read reads the sparse file data in expanded form.
+func (sfr *sparseFileReader) Read(b []byte) (n int, err error) {
+	// Skip past all empty fragments.
+	for len(sfr.sp) > 0 && sfr.sp[0].numBytes == 0 {
+		sfr.sp = sfr.sp[1:]
+	}
+
+	// If there are no more fragments, then it is possible that there
+	// is one last sparse hole.
+	if len(sfr.sp) == 0 {
+		// This behavior matches the BSD tar utility.
+		// However, GNU tar stops returning data even if sfr.total is unmet.
+		if sfr.pos < sfr.total {
+			return sfr.readHole(b, sfr.total), nil
+		}
+		return 0, io.EOF
+	}
+
+	// In front of a data fragment, so read a hole.
+	if sfr.pos < sfr.sp[0].offset {
+		return sfr.readHole(b, sfr.sp[0].offset), nil
+	}
+
+	// In a data fragment, so read from it.
+	// This math is overflow free since we verify that offset and numBytes can
+	// be safely added when creating the sparseFileReader.
+	endPos := sfr.sp[0].offset + sfr.sp[0].numBytes // End offset of fragment
+	bytesLeft := endPos - sfr.pos                   // Bytes left in fragment
+	if int64(len(b)) > bytesLeft {
+		b = b[:bytesLeft]
+	}
+
+	n, err = sfr.rfr.Read(b)
+	sfr.pos += int64(n)
+	if err == io.EOF {
+		if sfr.pos < endPos {
+			err = io.ErrUnexpectedEOF // There was supposed to be more data
+		} else if sfr.pos < sfr.total {
+			err = nil // There is still an implicit sparse hole at the end
+		}
+	}
+
+	if sfr.pos == endPos {
+		sfr.sp = sfr.sp[1:] // We are done with this fragment, so pop it
+	}
+	return n, err
+}
+
+// numBytes returns the number of bytes left to read in the sparse file's
+// sparse-encoded data in the tar archive.
+func (sfr *sparseFileReader) numBytes() int64 {
+	return sfr.rfr.numBytes()
+}
diff --git a/vendor/github.com/vbatts/tar-split/archive/tar/stat_atim.go b/vendor/github.com/vbatts/tar-split/archive/tar/stat_atim.go
new file mode 100644
index 000000000..cf9cc79c5
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/archive/tar/stat_atim.go
@@ -0,0 +1,20 @@
+// Copyright 2012 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.
+
+// +build linux dragonfly openbsd solaris
+
+package tar
+
+import (
+	"syscall"
+	"time"
+)
+
+func statAtime(st *syscall.Stat_t) time.Time {
+	return time.Unix(st.Atim.Unix())
+}
+
+func statCtime(st *syscall.Stat_t) time.Time {
+	return time.Unix(st.Ctim.Unix())
+}
diff --git a/vendor/github.com/vbatts/tar-split/archive/tar/stat_atimespec.go b/vendor/github.com/vbatts/tar-split/archive/tar/stat_atimespec.go
new file mode 100644
index 000000000..6f17dbe30
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/archive/tar/stat_atimespec.go
@@ -0,0 +1,20 @@
+// Copyright 2012 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.
+
+// +build darwin freebsd netbsd
+
+package tar
+
+import (
+	"syscall"
+	"time"
+)
+
+func statAtime(st *syscall.Stat_t) time.Time {
+	return time.Unix(st.Atimespec.Unix())
+}
+
+func statCtime(st *syscall.Stat_t) time.Time {
+	return time.Unix(st.Ctimespec.Unix())
+}
diff --git a/vendor/github.com/vbatts/tar-split/archive/tar/stat_unix.go b/vendor/github.com/vbatts/tar-split/archive/tar/stat_unix.go
new file mode 100644
index 000000000..cb843db4c
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/archive/tar/stat_unix.go
@@ -0,0 +1,32 @@
+// Copyright 2012 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.
+
+// +build linux darwin dragonfly freebsd openbsd netbsd solaris
+
+package tar
+
+import (
+	"os"
+	"syscall"
+)
+
+func init() {
+	sysStat = statUnix
+}
+
+func statUnix(fi os.FileInfo, h *Header) error {
+	sys, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return nil
+	}
+	h.Uid = int(sys.Uid)
+	h.Gid = int(sys.Gid)
+	// TODO(bradfitz): populate username & group.  os/user
+	// doesn't cache LookupId lookups, and lacks group
+	// lookup functions.
+	h.AccessTime = statAtime(sys)
+	h.ChangeTime = statCtime(sys)
+	// TODO(bradfitz): major/minor device numbers?
+	return nil
+}
diff --git a/vendor/github.com/vbatts/tar-split/archive/tar/writer.go b/vendor/github.com/vbatts/tar-split/archive/tar/writer.go
new file mode 100644
index 000000000..042638175
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/archive/tar/writer.go
@@ -0,0 +1,416 @@
+// 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.
+
+package tar
+
+// TODO(dsymonds):
+// - catch more errors (no first header, etc.)
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"path"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var (
+	ErrWriteTooLong    = errors.New("archive/tar: write too long")
+	ErrFieldTooLong    = errors.New("archive/tar: header field too long")
+	ErrWriteAfterClose = errors.New("archive/tar: write after close")
+	errInvalidHeader   = errors.New("archive/tar: header field too long or contains invalid values")
+)
+
+// A Writer provides sequential writing of a tar archive in POSIX.1 format.
+// A tar archive consists of a sequence of files.
+// Call WriteHeader to begin a new file, and then call Write to supply that file's data,
+// writing at most hdr.Size bytes in total.
+type Writer struct {
+	w          io.Writer
+	err        error
+	nb         int64 // number of unwritten bytes for current file entry
+	pad        int64 // amount of padding to write after current file entry
+	closed     bool
+	usedBinary bool            // whether the binary numeric field extension was used
+	preferPax  bool            // use pax header instead of binary numeric header
+	hdrBuff    [blockSize]byte // buffer to use in writeHeader when writing a regular header
+	paxHdrBuff [blockSize]byte // buffer to use in writeHeader when writing a pax header
+}
+
+type formatter struct {
+	err error // Last error seen
+}
+
+// NewWriter creates a new Writer writing to w.
+func NewWriter(w io.Writer) *Writer { return &Writer{w: w} }
+
+// Flush finishes writing the current file (optional).
+func (tw *Writer) Flush() error {
+	if tw.nb > 0 {
+		tw.err = fmt.Errorf("archive/tar: missed writing %d bytes", tw.nb)
+		return tw.err
+	}
+
+	n := tw.nb + tw.pad
+	for n > 0 && tw.err == nil {
+		nr := n
+		if nr > blockSize {
+			nr = blockSize
+		}
+		var nw int
+		nw, tw.err = tw.w.Write(zeroBlock[0:nr])
+		n -= int64(nw)
+	}
+	tw.nb = 0
+	tw.pad = 0
+	return tw.err
+}
+
+// Write s into b, terminating it with a NUL if there is room.
+func (f *formatter) formatString(b []byte, s string) {
+	if len(s) > len(b) {
+		f.err = ErrFieldTooLong
+		return
+	}
+	ascii := toASCII(s)
+	copy(b, ascii)
+	if len(ascii) < len(b) {
+		b[len(ascii)] = 0
+	}
+}
+
+// Encode x as an octal ASCII string and write it into b with leading zeros.
+func (f *formatter) formatOctal(b []byte, x int64) {
+	s := strconv.FormatInt(x, 8)
+	// leading zeros, but leave room for a NUL.
+	for len(s)+1 < len(b) {
+		s = "0" + s
+	}
+	f.formatString(b, s)
+}
+
+// fitsInBase256 reports whether x can be encoded into n bytes using base-256
+// encoding. Unlike octal encoding, base-256 encoding does not require that the
+// string ends with a NUL character. Thus, all n bytes are available for output.
+//
+// If operating in binary mode, this assumes strict GNU binary mode; which means
+// that the first byte can only be either 0x80 or 0xff. Thus, the first byte is
+// equivalent to the sign bit in two's complement form.
+func fitsInBase256(n int, x int64) bool {
+	var binBits = uint(n-1) * 8
+	return n >= 9 || (x >= -1<<binBits && x < 1<<binBits)
+}
+
+// Write x into b, as binary (GNUtar/star extension).
+func (f *formatter) formatNumeric(b []byte, x int64) {
+	if fitsInBase256(len(b), x) {
+		for i := len(b) - 1; i >= 0; i-- {
+			b[i] = byte(x)
+			x >>= 8
+		}
+		b[0] |= 0x80 // Highest bit indicates binary format
+		return
+	}
+
+	f.formatOctal(b, 0) // Last resort, just write zero
+	f.err = ErrFieldTooLong
+}
+
+var (
+	minTime = time.Unix(0, 0)
+	// There is room for 11 octal digits (33 bits) of mtime.
+	maxTime = minTime.Add((1<<33 - 1) * time.Second)
+)
+
+// WriteHeader writes hdr and prepares to accept the file's contents.
+// WriteHeader calls Flush if it is not the first header.
+// Calling after a Close will return ErrWriteAfterClose.
+func (tw *Writer) WriteHeader(hdr *Header) error {
+	return tw.writeHeader(hdr, true)
+}
+
+// WriteHeader writes hdr and prepares to accept the file's contents.
+// WriteHeader calls Flush if it is not the first header.
+// Calling after a Close will return ErrWriteAfterClose.
+// As this method is called internally by writePax header to allow it to
+// suppress writing the pax header.
+func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
+	if tw.closed {
+		return ErrWriteAfterClose
+	}
+	if tw.err == nil {
+		tw.Flush()
+	}
+	if tw.err != nil {
+		return tw.err
+	}
+
+	// a map to hold pax header records, if any are needed
+	paxHeaders := make(map[string]string)
+
+	// TODO(shanemhansen): we might want to use PAX headers for
+	// subsecond time resolution, but for now let's just capture
+	// too long fields or non ascii characters
+
+	var f formatter
+	var header []byte
+
+	// We need to select which scratch buffer to use carefully,
+	// since this method is called recursively to write PAX headers.
+	// If allowPax is true, this is the non-recursive call, and we will use hdrBuff.
+	// If allowPax is false, we are being called by writePAXHeader, and hdrBuff is
+	// already being used by the non-recursive call, so we must use paxHdrBuff.
+	header = tw.hdrBuff[:]
+	if !allowPax {
+		header = tw.paxHdrBuff[:]
+	}
+	copy(header, zeroBlock)
+	s := slicer(header)
+
+	// Wrappers around formatter that automatically sets paxHeaders if the
+	// argument extends beyond the capacity of the input byte slice.
+	var formatString = func(b []byte, s string, paxKeyword string) {
+		needsPaxHeader := paxKeyword != paxNone && len(s) > len(b) || !isASCII(s)
+		if needsPaxHeader {
+			paxHeaders[paxKeyword] = s
+			return
+		}
+		f.formatString(b, s)
+	}
+	var formatNumeric = func(b []byte, x int64, paxKeyword string) {
+		// Try octal first.
+		s := strconv.FormatInt(x, 8)
+		if len(s) < len(b) {
+			f.formatOctal(b, x)
+			return
+		}
+
+		// If it is too long for octal, and PAX is preferred, use a PAX header.
+		if paxKeyword != paxNone && tw.preferPax {
+			f.formatOctal(b, 0)
+			s := strconv.FormatInt(x, 10)
+			paxHeaders[paxKeyword] = s
+			return
+		}
+
+		tw.usedBinary = true
+		f.formatNumeric(b, x)
+	}
+
+	// keep a reference to the filename to allow to overwrite it later if we detect that we can use ustar longnames instead of pax
+	pathHeaderBytes := s.next(fileNameSize)
+
+	formatString(pathHeaderBytes, hdr.Name, paxPath)
+
+	// Handle out of range ModTime carefully.
+	var modTime int64
+	if !hdr.ModTime.Before(minTime) && !hdr.ModTime.After(maxTime) {
+		modTime = hdr.ModTime.Unix()
+	}
+
+	f.formatOctal(s.next(8), hdr.Mode)               // 100:108
+	formatNumeric(s.next(8), int64(hdr.Uid), paxUid) // 108:116
+	formatNumeric(s.next(8), int64(hdr.Gid), paxGid) // 116:124
+	formatNumeric(s.next(12), hdr.Size, paxSize)     // 124:136
+	formatNumeric(s.next(12), modTime, paxNone)      // 136:148 --- consider using pax for finer granularity
+	s.next(8)                                        // chksum (148:156)
+	s.next(1)[0] = hdr.Typeflag                      // 156:157
+
+	formatString(s.next(100), hdr.Linkname, paxLinkpath)
+
+	copy(s.next(8), []byte("ustar\x0000"))          // 257:265
+	formatString(s.next(32), hdr.Uname, paxUname)   // 265:297
+	formatString(s.next(32), hdr.Gname, paxGname)   // 297:329
+	formatNumeric(s.next(8), hdr.Devmajor, paxNone) // 329:337
+	formatNumeric(s.next(8), hdr.Devminor, paxNone) // 337:345
+
+	// keep a reference to the prefix to allow to overwrite it later if we detect that we can use ustar longnames instead of pax
+	prefixHeaderBytes := s.next(155)
+	formatString(prefixHeaderBytes, "", paxNone) // 345:500  prefix
+
+	// Use the GNU magic instead of POSIX magic if we used any GNU extensions.
+	if tw.usedBinary {
+		copy(header[257:265], []byte("ustar  \x00"))
+	}
+
+	_, paxPathUsed := paxHeaders[paxPath]
+	// try to use a ustar header when only the name is too long
+	if !tw.preferPax && len(paxHeaders) == 1 && paxPathUsed {
+		prefix, suffix, ok := splitUSTARPath(hdr.Name)
+		if ok {
+			// Since we can encode in USTAR format, disable PAX header.
+			delete(paxHeaders, paxPath)
+
+			// Update the path fields
+			formatString(pathHeaderBytes, suffix, paxNone)
+			formatString(prefixHeaderBytes, prefix, paxNone)
+		}
+	}
+
+	// The chksum field is terminated by a NUL and a space.
+	// This is different from the other octal fields.
+	chksum, _ := checksum(header)
+	f.formatOctal(header[148:155], chksum) // Never fails
+	header[155] = ' '
+
+	// Check if there were any formatting errors.
+	if f.err != nil {
+		tw.err = f.err
+		return tw.err
+	}
+
+	if allowPax {
+		for k, v := range hdr.Xattrs {
+			paxHeaders[paxXattr+k] = v
+		}
+	}
+
+	if len(paxHeaders) > 0 {
+		if !allowPax {
+			return errInvalidHeader
+		}
+		if err := tw.writePAXHeader(hdr, paxHeaders); err != nil {
+			return err
+		}
+	}
+	tw.nb = int64(hdr.Size)
+	tw.pad = (blockSize - (tw.nb % blockSize)) % blockSize
+
+	_, tw.err = tw.w.Write(header)
+	return tw.err
+}
+
+// splitUSTARPath splits a path according to USTAR prefix and suffix rules.
+// If the path is not splittable, then it will return ("", "", false).
+func splitUSTARPath(name string) (prefix, suffix string, ok bool) {
+	length := len(name)
+	if length <= fileNameSize || !isASCII(name) {
+		return "", "", false
+	} else if length > fileNamePrefixSize+1 {
+		length = fileNamePrefixSize + 1
+	} else if name[length-1] == '/' {
+		length--
+	}
+
+	i := strings.LastIndex(name[:length], "/")
+	nlen := len(name) - i - 1 // nlen is length of suffix
+	plen := i                 // plen is length of prefix
+	if i <= 0 || nlen > fileNameSize || nlen == 0 || plen > fileNamePrefixSize {
+		return "", "", false
+	}
+	return name[:i], name[i+1:], true
+}
+
+// writePaxHeader writes an extended pax header to the
+// archive.
+func (tw *Writer) writePAXHeader(hdr *Header, paxHeaders map[string]string) error {
+	// Prepare extended header
+	ext := new(Header)
+	ext.Typeflag = TypeXHeader
+	// Setting ModTime is required for reader parsing to
+	// succeed, and seems harmless enough.
+	ext.ModTime = hdr.ModTime
+	// The spec asks that we namespace our pseudo files
+	// with the current pid.  However, this results in differing outputs
+	// for identical inputs.  As such, the constant 0 is now used instead.
+	// golang.org/issue/12358
+	dir, file := path.Split(hdr.Name)
+	fullName := path.Join(dir, "PaxHeaders.0", file)
+
+	ascii := toASCII(fullName)
+	if len(ascii) > 100 {
+		ascii = ascii[:100]
+	}
+	ext.Name = ascii
+	// Construct the body
+	var buf bytes.Buffer
+
+	// Keys are sorted before writing to body to allow deterministic output.
+	var keys []string
+	for k := range paxHeaders {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+
+	for _, k := range keys {
+		fmt.Fprint(&buf, formatPAXRecord(k, paxHeaders[k]))
+	}
+
+	ext.Size = int64(len(buf.Bytes()))
+	if err := tw.writeHeader(ext, false); err != nil {
+		return err
+	}
+	if _, err := tw.Write(buf.Bytes()); err != nil {
+		return err
+	}
+	if err := tw.Flush(); err != nil {
+		return err
+	}
+	return nil
+}
+
+// formatPAXRecord formats a single PAX record, prefixing it with the
+// appropriate length.
+func formatPAXRecord(k, v string) string {
+	const padding = 3 // Extra padding for ' ', '=', and '\n'
+	size := len(k) + len(v) + padding
+	size += len(strconv.Itoa(size))
+	record := fmt.Sprintf("%d %s=%s\n", size, k, v)
+
+	// Final adjustment if adding size field increased the record size.
+	if len(record) != size {
+		size = len(record)
+		record = fmt.Sprintf("%d %s=%s\n", size, k, v)
+	}
+	return record
+}
+
+// Write writes to the current entry in the tar archive.
+// Write returns the error ErrWriteTooLong if more than
+// hdr.Size bytes are written after WriteHeader.
+func (tw *Writer) Write(b []byte) (n int, err error) {
+	if tw.closed {
+		err = ErrWriteAfterClose
+		return
+	}
+	overwrite := false
+	if int64(len(b)) > tw.nb {
+		b = b[0:tw.nb]
+		overwrite = true
+	}
+	n, err = tw.w.Write(b)
+	tw.nb -= int64(n)
+	if err == nil && overwrite {
+		err = ErrWriteTooLong
+		return
+	}
+	tw.err = err
+	return
+}
+
+// Close closes the tar archive, flushing any unwritten
+// data to the underlying writer.
+func (tw *Writer) Close() error {
+	if tw.err != nil || tw.closed {
+		return tw.err
+	}
+	tw.Flush()
+	tw.closed = true
+	if tw.err != nil {
+		return tw.err
+	}
+
+	// trailer: two zero blocks
+	for i := 0; i < 2; i++ {
+		_, tw.err = tw.w.Write(zeroBlock)
+		if tw.err != nil {
+			break
+		}
+	}
+	return tw.err
+}
diff --git a/vendor/github.com/vbatts/tar-split/tar/asm/README.md b/vendor/github.com/vbatts/tar-split/tar/asm/README.md
new file mode 100644
index 000000000..2a3a5b56a
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/tar/asm/README.md
@@ -0,0 +1,44 @@
+asm
+===
+
+This library for assembly and disassembly of tar archives, facilitated by
+`github.com/vbatts/tar-split/tar/storage`.
+
+
+Concerns
+--------
+
+For completely safe assembly/disassembly, there will need to be a Content
+Addressable Storage (CAS) directory, that maps to a checksum in the
+`storage.Entity` of `storage.FileType`.
+
+This is due to the fact that tar archives _can_ allow multiple records for the
+same path, but the last one effectively wins. Even if the prior records had a
+different payload. 
+
+In this way, when assembling an archive from relative paths, if the archive has
+multiple entries for the same path, then all payloads read in from a relative
+path would be identical.
+
+
+Thoughts
+--------
+
+Have a look-aside directory or storage. This way when a clobbering record is
+encountered from the tar stream, then the payload of the prior/existing file is
+stored to the CAS. This way the clobbering record's file payload can be
+extracted, but we'll have preserved the payload needed to reassemble a precise
+tar archive.
+
+clobbered/path/to/file.[0-N]
+
+*alternatively*
+
+We could just _not_ support tar streams that have clobbering file paths.
+Appending records to the archive is not incredibly common, and doesn't happen
+by default for most implementations.  Not supporting them wouldn't be a
+security concern either, as if it did occur, we would reassemble an archive
+that doesn't validate signature/checksum, so it shouldn't be trusted anyway.
+
+Otherwise, this will allow us to defer support for appended files as a FUTURE FEATURE.
+
diff --git a/vendor/github.com/vbatts/tar-split/tar/asm/assemble.go b/vendor/github.com/vbatts/tar-split/tar/asm/assemble.go
new file mode 100644
index 000000000..d624450ab
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/tar/asm/assemble.go
@@ -0,0 +1,130 @@
+package asm
+
+import (
+	"bytes"
+	"fmt"
+	"hash"
+	"hash/crc64"
+	"io"
+	"sync"
+
+	"github.com/vbatts/tar-split/tar/storage"
+)
+
+// NewOutputTarStream returns an io.ReadCloser that is an assembled tar archive
+// stream.
+//
+// It takes a storage.FileGetter, for mapping the file payloads that are to be read in,
+// and a storage.Unpacker, which has access to the rawbytes and file order
+// metadata. With the combination of these two items, a precise assembled Tar
+// archive is possible.
+func NewOutputTarStream(fg storage.FileGetter, up storage.Unpacker) io.ReadCloser {
+	// ... Since these are interfaces, this is possible, so let's not have a nil pointer
+	if fg == nil || up == nil {
+		return nil
+	}
+	pr, pw := io.Pipe()
+	go func() {
+		err := WriteOutputTarStream(fg, up, pw)
+		if err != nil {
+			pw.CloseWithError(err)
+		} else {
+			pw.Close()
+		}
+	}()
+	return pr
+}
+
+// WriteOutputTarStream writes assembled tar archive to a writer.
+func WriteOutputTarStream(fg storage.FileGetter, up storage.Unpacker, w io.Writer) error {
+	// ... Since these are interfaces, this is possible, so let's not have a nil pointer
+	if fg == nil || up == nil {
+		return nil
+	}
+	var copyBuffer []byte
+	var crcHash hash.Hash
+	var crcSum []byte
+	var multiWriter io.Writer
+	for {
+		entry, err := up.Next()
+		if err != nil {
+			if err == io.EOF {
+				return nil
+			}
+			return err
+		}
+		switch entry.Type {
+		case storage.SegmentType:
+			if _, err := w.Write(entry.Payload); err != nil {
+				return err
+			}
+		case storage.FileType:
+			if entry.Size == 0 {
+				continue
+			}
+			fh, err := fg.Get(entry.GetName())
+			if err != nil {
+				return err
+			}
+			if crcHash == nil {
+				crcHash = crc64.New(storage.CRCTable)
+				crcSum = make([]byte, 8)
+				multiWriter = io.MultiWriter(w, crcHash)
+				copyBuffer = byteBufferPool.Get().([]byte)
+				defer byteBufferPool.Put(copyBuffer)
+			} else {
+				crcHash.Reset()
+			}
+
+			if _, err := copyWithBuffer(multiWriter, fh, copyBuffer); err != nil {
+				fh.Close()
+				return err
+			}
+
+			if !bytes.Equal(crcHash.Sum(crcSum[:0]), entry.Payload) {
+				// I would rather this be a comparable ErrInvalidChecksum or such,
+				// but since it's coming through the PipeReader, the context of
+				// _which_ file would be lost...
+				fh.Close()
+				return fmt.Errorf("file integrity checksum failed for %q", entry.GetName())
+			}
+			fh.Close()
+		}
+	}
+}
+
+var byteBufferPool = &sync.Pool{
+	New: func() interface{} {
+		return make([]byte, 32*1024)
+	},
+}
+
+// copyWithBuffer is taken from stdlib io.Copy implementation
+// https://github.com/golang/go/blob/go1.5.1/src/io/io.go#L367
+func copyWithBuffer(dst io.Writer, src io.Reader, buf []byte) (written int64, err error) {
+	for {
+		nr, er := src.Read(buf)
+		if nr > 0 {
+			nw, ew := dst.Write(buf[0:nr])
+			if nw > 0 {
+				written += int64(nw)
+			}
+			if ew != nil {
+				err = ew
+				break
+			}
+			if nr != nw {
+				err = io.ErrShortWrite
+				break
+			}
+		}
+		if er == io.EOF {
+			break
+		}
+		if er != nil {
+			err = er
+			break
+		}
+	}
+	return written, err
+}
diff --git a/vendor/github.com/vbatts/tar-split/tar/asm/disassemble.go b/vendor/github.com/vbatts/tar-split/tar/asm/disassemble.go
new file mode 100644
index 000000000..54ef23aed
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/tar/asm/disassemble.go
@@ -0,0 +1,141 @@
+package asm
+
+import (
+	"io"
+	"io/ioutil"
+
+	"github.com/vbatts/tar-split/archive/tar"
+	"github.com/vbatts/tar-split/tar/storage"
+)
+
+// NewInputTarStream wraps the Reader stream of a tar archive and provides a
+// Reader stream of the same.
+//
+// In the middle it will pack the segments and file metadata to storage.Packer
+// `p`.
+//
+// The the storage.FilePutter is where payload of files in the stream are
+// stashed. If this stashing is not needed, you can provide a nil
+// storage.FilePutter. Since the checksumming is still needed, then a default
+// of NewDiscardFilePutter will be used internally
+func NewInputTarStream(r io.Reader, p storage.Packer, fp storage.FilePutter) (io.Reader, error) {
+	// What to do here... folks will want their own access to the Reader that is
+	// their tar archive stream, but we'll need that same stream to use our
+	// forked 'archive/tar'.
+	// Perhaps do an io.TeeReader that hands back an io.Reader for them to read
+	// from, and we'll MITM the stream to store metadata.
+	// We'll need a storage.FilePutter too ...
+
+	// Another concern, whether to do any storage.FilePutter operations, such that we
+	// don't extract any amount of the archive. But then again, we're not making
+	// files/directories, hardlinks, etc. Just writing the io to the storage.FilePutter.
+	// Perhaps we have a DiscardFilePutter that is a bit bucket.
+
+	// we'll return the pipe reader, since TeeReader does not buffer and will
+	// only read what the outputRdr Read's. Since Tar archives have padding on
+	// the end, we want to be the one reading the padding, even if the user's
+	// `archive/tar` doesn't care.
+	pR, pW := io.Pipe()
+	outputRdr := io.TeeReader(r, pW)
+
+	// we need a putter that will generate the crc64 sums of file payloads
+	if fp == nil {
+		fp = storage.NewDiscardFilePutter()
+	}
+
+	go func() {
+		tr := tar.NewReader(outputRdr)
+		tr.RawAccounting = true
+		for {
+			hdr, err := tr.Next()
+			if err != nil {
+				if err != io.EOF {
+					pW.CloseWithError(err)
+					return
+				}
+				// even when an EOF is reached, there is often 1024 null bytes on
+				// the end of an archive. Collect them too.
+				if b := tr.RawBytes(); len(b) > 0 {
+					_, err := p.AddEntry(storage.Entry{
+						Type:    storage.SegmentType,
+						Payload: b,
+					})
+					if err != nil {
+						pW.CloseWithError(err)
+						return
+					}
+				}
+				break // not return. We need the end of the reader.
+			}
+			if hdr == nil {
+				break // not return. We need the end of the reader.
+			}
+
+			if b := tr.RawBytes(); len(b) > 0 {
+				_, err := p.AddEntry(storage.Entry{
+					Type:    storage.SegmentType,
+					Payload: b,
+				})
+				if err != nil {
+					pW.CloseWithError(err)
+					return
+				}
+			}
+
+			var csum []byte
+			if hdr.Size > 0 {
+				var err error
+				_, csum, err = fp.Put(hdr.Name, tr)
+				if err != nil {
+					pW.CloseWithError(err)
+					return
+				}
+			}
+
+			entry := storage.Entry{
+				Type:    storage.FileType,
+				Size:    hdr.Size,
+				Payload: csum,
+			}
+			// For proper marshalling of non-utf8 characters
+			entry.SetName(hdr.Name)
+
+			// File entries added, regardless of size
+			_, err = p.AddEntry(entry)
+			if err != nil {
+				pW.CloseWithError(err)
+				return
+			}
+
+			if b := tr.RawBytes(); len(b) > 0 {
+				_, err = p.AddEntry(storage.Entry{
+					Type:    storage.SegmentType,
+					Payload: b,
+				})
+				if err != nil {
+					pW.CloseWithError(err)
+					return
+				}
+			}
+		}
+
+		// it is allowable, and not uncommon that there is further padding on the
+		// end of an archive, apart from the expected 1024 null bytes.
+		remainder, err := ioutil.ReadAll(outputRdr)
+		if err != nil && err != io.EOF {
+			pW.CloseWithError(err)
+			return
+		}
+		_, err = p.AddEntry(storage.Entry{
+			Type:    storage.SegmentType,
+			Payload: remainder,
+		})
+		if err != nil {
+			pW.CloseWithError(err)
+			return
+		}
+		pW.Close()
+	}()
+
+	return pR, nil
+}
diff --git a/vendor/github.com/vbatts/tar-split/tar/asm/doc.go b/vendor/github.com/vbatts/tar-split/tar/asm/doc.go
new file mode 100644
index 000000000..4367b9022
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/tar/asm/doc.go
@@ -0,0 +1,9 @@
+/*
+Package asm provides the API for streaming assembly and disassembly of tar
+archives.
+
+Using the `github.com/vbatts/tar-split/tar/storage` for Packing/Unpacking the
+metadata for a stream, as well as an implementation of Getting/Putting the file
+entries' payload.
+*/
+package asm
diff --git a/vendor/github.com/vbatts/tar-split/tar/storage/doc.go b/vendor/github.com/vbatts/tar-split/tar/storage/doc.go
new file mode 100644
index 000000000..83f7089ff
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/tar/storage/doc.go
@@ -0,0 +1,12 @@
+/*
+Package storage is for metadata of a tar archive.
+
+Packing and unpacking the Entries of the stream. The types of streams are
+either segments of raw bytes (for the raw headers and various padding) and for
+an entry marking a file payload.
+
+The raw bytes are stored precisely in the packed (marshalled) Entry, whereas
+the file payload marker include the name of the file, size, and crc64 checksum
+(for basic file integrity).
+*/
+package storage
diff --git a/vendor/github.com/vbatts/tar-split/tar/storage/entry.go b/vendor/github.com/vbatts/tar-split/tar/storage/entry.go
new file mode 100644
index 000000000..c91e7ea1e
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/tar/storage/entry.go
@@ -0,0 +1,78 @@
+package storage
+
+import "unicode/utf8"
+
+// Entries is for sorting by Position
+type Entries []Entry
+
+func (e Entries) Len() int           { return len(e) }
+func (e Entries) Swap(i, j int)      { e[i], e[j] = e[j], e[i] }
+func (e Entries) Less(i, j int) bool { return e[i].Position < e[j].Position }
+
+// Type of Entry
+type Type int
+
+const (
+	// FileType represents a file payload from the tar stream.
+	//
+	// This will be used to map to relative paths on disk. Only Size > 0 will get
+	// read into a resulting output stream (due to hardlinks).
+	FileType Type = 1 + iota
+	// SegmentType represents a raw bytes segment from the archive stream. These raw
+	// byte segments consist of the raw headers and various padding.
+	//
+	// Its payload is to be marshalled base64 encoded.
+	SegmentType
+)
+
+// Entry is the structure for packing and unpacking the information read from
+// the Tar archive.
+//
+// FileType Payload checksum is using `hash/crc64` for basic file integrity,
+// _not_ for cryptography.
+// From http://www.backplane.com/matt/crc64.html, CRC32 has almost 40,000
+// collisions in a sample of 18.2 million, CRC64 had none.
+type Entry struct {
+	Type     Type   `json:"type"`
+	Name     string `json:"name,omitempty"`
+	NameRaw  []byte `json:"name_raw,omitempty"`
+	Size     int64  `json:"size,omitempty"`
+	Payload  []byte `json:"payload"` // SegmentType stores payload here; FileType stores crc64 checksum here;
+	Position int    `json:"position"`
+}
+
+// SetName will check name for valid UTF-8 string, and set the appropriate
+// field. See https://github.com/vbatts/tar-split/issues/17
+func (e *Entry) SetName(name string) {
+	if utf8.ValidString(name) {
+		e.Name = name
+	} else {
+		e.NameRaw = []byte(name)
+	}
+}
+
+// SetNameBytes will check name for valid UTF-8 string, and set the appropriate
+// field
+func (e *Entry) SetNameBytes(name []byte) {
+	if utf8.Valid(name) {
+		e.Name = string(name)
+	} else {
+		e.NameRaw = name
+	}
+}
+
+// GetName returns the string for the entry's name, regardless of the field stored in
+func (e *Entry) GetName() string {
+	if len(e.NameRaw) > 0 {
+		return string(e.NameRaw)
+	}
+	return e.Name
+}
+
+// GetNameBytes returns the bytes for the entry's name, regardless of the field stored in
+func (e *Entry) GetNameBytes() []byte {
+	if len(e.NameRaw) > 0 {
+		return e.NameRaw
+	}
+	return []byte(e.Name)
+}
diff --git a/vendor/github.com/vbatts/tar-split/tar/storage/getter.go b/vendor/github.com/vbatts/tar-split/tar/storage/getter.go
new file mode 100644
index 000000000..ae11f8ffd
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/tar/storage/getter.go
@@ -0,0 +1,104 @@
+package storage
+
+import (
+	"bytes"
+	"errors"
+	"hash/crc64"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+// FileGetter is the interface for getting a stream of a file payload,
+// addressed by name/filename. Presumably, the names will be scoped to relative
+// file paths.
+type FileGetter interface {
+	// Get returns a stream for the provided file path
+	Get(filename string) (output io.ReadCloser, err error)
+}
+
+// FilePutter is the interface for storing a stream of a file payload,
+// addressed by name/filename.
+type FilePutter interface {
+	// Put returns the size of the stream received, and the crc64 checksum for
+	// the provided stream
+	Put(filename string, input io.Reader) (size int64, checksum []byte, err error)
+}
+
+// FileGetPutter is the interface that groups both Getting and Putting file
+// payloads.
+type FileGetPutter interface {
+	FileGetter
+	FilePutter
+}
+
+// NewPathFileGetter returns a FileGetter that is for files relative to path
+// relpath.
+func NewPathFileGetter(relpath string) FileGetter {
+	return &pathFileGetter{root: relpath}
+}
+
+type pathFileGetter struct {
+	root string
+}
+
+func (pfg pathFileGetter) Get(filename string) (io.ReadCloser, error) {
+	return os.Open(filepath.Join(pfg.root, filename))
+}
+
+type bufferFileGetPutter struct {
+	files map[string][]byte
+}
+
+func (bfgp bufferFileGetPutter) Get(name string) (io.ReadCloser, error) {
+	if _, ok := bfgp.files[name]; !ok {
+		return nil, errors.New("no such file")
+	}
+	b := bytes.NewBuffer(bfgp.files[name])
+	return &readCloserWrapper{b}, nil
+}
+
+func (bfgp *bufferFileGetPutter) Put(name string, r io.Reader) (int64, []byte, error) {
+	crc := crc64.New(CRCTable)
+	buf := bytes.NewBuffer(nil)
+	cw := io.MultiWriter(crc, buf)
+	i, err := io.Copy(cw, r)
+	if err != nil {
+		return 0, nil, err
+	}
+	bfgp.files[name] = buf.Bytes()
+	return i, crc.Sum(nil), nil
+}
+
+type readCloserWrapper struct {
+	io.Reader
+}
+
+func (w *readCloserWrapper) Close() error { return nil }
+
+// NewBufferFileGetPutter is a simple in-memory FileGetPutter
+//
+// Implication is this is memory intensive...
+// Probably best for testing or light weight cases.
+func NewBufferFileGetPutter() FileGetPutter {
+	return &bufferFileGetPutter{
+		files: map[string][]byte{},
+	}
+}
+
+// NewDiscardFilePutter is a bit bucket FilePutter
+func NewDiscardFilePutter() FilePutter {
+	return &bitBucketFilePutter{}
+}
+
+type bitBucketFilePutter struct {
+}
+
+func (bbfp *bitBucketFilePutter) Put(name string, r io.Reader) (int64, []byte, error) {
+	c := crc64.New(CRCTable)
+	i, err := io.Copy(c, r)
+	return i, c.Sum(nil), err
+}
+
+// CRCTable is the default table used for crc64 sum calculations
+var CRCTable = crc64.MakeTable(crc64.ISO)
diff --git a/vendor/github.com/vbatts/tar-split/tar/storage/packer.go b/vendor/github.com/vbatts/tar-split/tar/storage/packer.go
new file mode 100644
index 000000000..aba694818
--- /dev/null
+++ b/vendor/github.com/vbatts/tar-split/tar/storage/packer.go
@@ -0,0 +1,127 @@
+package storage
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"path/filepath"
+	"unicode/utf8"
+)
+
+// ErrDuplicatePath occurs when a tar archive has more than one entry for the
+// same file path
+var ErrDuplicatePath = errors.New("duplicates of file paths not supported")
+
+// Packer describes the methods to pack Entries to a storage destination
+type Packer interface {
+	// AddEntry packs the Entry and returns its position
+	AddEntry(e Entry) (int, error)
+}
+
+// Unpacker describes the methods to read Entries from a source
+type Unpacker interface {
+	// Next returns the next Entry being unpacked, or error, until io.EOF
+	Next() (*Entry, error)
+}
+
+/* TODO(vbatts) figure out a good model for this
+type PackUnpacker interface {
+	Packer
+	Unpacker
+}
+*/
+
+type jsonUnpacker struct {
+	seen seenNames
+	dec  *json.Decoder
+}
+
+func (jup *jsonUnpacker) Next() (*Entry, error) {
+	var e Entry
+	err := jup.dec.Decode(&e)
+	if err != nil {
+		return nil, err
+	}
+
+	// check for dup name
+	if e.Type == FileType {
+		cName := filepath.Clean(e.GetName())
+		if _, ok := jup.seen[cName]; ok {
+			return nil, ErrDuplicatePath
+		}
+		jup.seen[cName] = struct{}{}
+	}
+
+	return &e, err
+}
+
+// NewJSONUnpacker provides an Unpacker that reads Entries (SegmentType and
+// FileType) as a json document.
+//
+// Each Entry read are expected to be delimited by new line.
+func NewJSONUnpacker(r io.Reader) Unpacker {
+	return &jsonUnpacker{
+		dec:  json.NewDecoder(r),
+		seen: seenNames{},
+	}
+}
+
+type jsonPacker struct {
+	w    io.Writer
+	e    *json.Encoder
+	pos  int
+	seen seenNames
+}
+
+type seenNames map[string]struct{}
+
+func (jp *jsonPacker) AddEntry(e Entry) (int, error) {
+	// if Name is not valid utf8, switch it to raw first.
+	if e.Name != "" {
+		if !utf8.ValidString(e.Name) {
+			e.NameRaw = []byte(e.Name)
+			e.Name = ""
+		}
+	}
+
+	// check early for dup name
+	if e.Type == FileType {
+		cName := filepath.Clean(e.GetName())
+		if _, ok := jp.seen[cName]; ok {
+			return -1, ErrDuplicatePath
+		}
+		jp.seen[cName] = struct{}{}
+	}
+
+	e.Position = jp.pos
+	err := jp.e.Encode(e)
+	if err != nil {
+		return -1, err
+	}
+
+	// made it this far, increment now
+	jp.pos++
+	return e.Position, nil
+}
+
+// NewJSONPacker provides a Packer that writes each Entry (SegmentType and
+// FileType) as a json document.
+//
+// The Entries are delimited by new line.
+func NewJSONPacker(w io.Writer) Packer {
+	return &jsonPacker{
+		w:    w,
+		e:    json.NewEncoder(w),
+		seen: seenNames{},
+	}
+}
+
+/*
+TODO(vbatts) perhaps have a more compact packer/unpacker, maybe using msgapck
+(https://github.com/ugorji/go)
+
+
+Even though, since our jsonUnpacker and jsonPacker just take
+io.Reader/io.Writer, then we can get away with passing them a
+gzip.Reader/gzip.Writer
+*/