Vendor in latest code for storage,image, buildah

vendor in containers/storage
vendor in containers/image
vendor in projectatomic/buildah

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

Closes: #1114
Approved by: mheon

41 files changed, 7232 insertions, 0 deletions

diff --git a/vendor/github.com/ulikunitz/xz/LICENSE b/vendor/github.com/ulikunitz/xz/LICENSE
new file mode 100644
index 000000000..58ebdc162
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/LICENSE
@@ -0,0 +1,26 @@
+Copyright (c) 2014-2016  Ulrich Kunitz
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* 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.
+
+* My name, Ulrich Kunitz, may not 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/ulikunitz/xz/README.md b/vendor/github.com/ulikunitz/xz/README.md
new file mode 100644
index 000000000..969ae7a00
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/README.md
@@ -0,0 +1,71 @@
+# Package xz
+
+This Go language package supports the reading and writing of xz
+compressed streams. It includes also a gxz command for compressing and
+decompressing data. The package is completely written in Go and doesn't
+have any dependency on any C code.
+
+The package is currently under development. There might be bugs and APIs
+are not considered stable. At this time the package cannot compete with
+the xz tool regarding compression speed and size. The algorithms there
+have been developed over a long time and are highly optimized. However
+there are a number of improvements planned and I'm very optimistic about
+parallel compression and decompression. Stay tuned!
+
+# Using the API
+
+The following example program shows how to use the API.
+
+    package main
+
+    import (
+        "bytes"
+        "io"
+        "log"
+        "os"
+
+        "github.com/ulikunitz/xz"
+    )
+
+    func main() {
+        const text = "The quick brown fox jumps over the lazy dog.\n"
+        var buf bytes.Buffer
+        // compress text
+        w, err := xz.NewWriter(&buf)
+        if err != nil {
+            log.Fatalf("xz.NewWriter error %s", err)
+        }
+        if _, err := io.WriteString(w, text); err != nil {
+            log.Fatalf("WriteString error %s", err)
+        }
+        if err := w.Close(); err != nil {
+            log.Fatalf("w.Close error %s", err)
+        }
+        // decompress buffer and write output to stdout
+        r, err := xz.NewReader(&buf)
+        if err != nil {
+            log.Fatalf("NewReader error %s", err)
+        }
+        if _, err = io.Copy(os.Stdout, r); err != nil {
+            log.Fatalf("io.Copy error %s", err)
+        }
+    }
+
+# Using the gxz compression tool
+
+The package includes a gxz command line utility for compression and
+decompression.
+
+Use following command for installation:
+
+    $ go get github.com/ulikunitz/xz/cmd/gxz
+
+To test it call the following command.
+
+    $ gxz bigfile
+
+After some time a much smaller file bigfile.xz will replace bigfile.
+To decompress it use the following command.
+
+    $ gxz -d bigfile.xz
+
diff --git a/vendor/github.com/ulikunitz/xz/bits.go b/vendor/github.com/ulikunitz/xz/bits.go
new file mode 100644
index 000000000..fadc1a594
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/bits.go
@@ -0,0 +1,74 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xz
+
+import (
+	"errors"
+	"io"
+)
+
+// putUint32LE puts the little-endian representation of x into the first
+// four bytes of p.
+func putUint32LE(p []byte, x uint32) {
+	p[0] = byte(x)
+	p[1] = byte(x >> 8)
+	p[2] = byte(x >> 16)
+	p[3] = byte(x >> 24)
+}
+
+// putUint64LE puts the little-endian representation of x into the first
+// eight bytes of p.
+func putUint64LE(p []byte, x uint64) {
+	p[0] = byte(x)
+	p[1] = byte(x >> 8)
+	p[2] = byte(x >> 16)
+	p[3] = byte(x >> 24)
+	p[4] = byte(x >> 32)
+	p[5] = byte(x >> 40)
+	p[6] = byte(x >> 48)
+	p[7] = byte(x >> 56)
+}
+
+// uint32LE converts a little endian representation to an uint32 value.
+func uint32LE(p []byte) uint32 {
+	return uint32(p[0]) | uint32(p[1])<<8 | uint32(p[2])<<16 |
+		uint32(p[3])<<24
+}
+
+// putUvarint puts a uvarint representation of x into the byte slice.
+func putUvarint(p []byte, x uint64) int {
+	i := 0
+	for x >= 0x80 {
+		p[i] = byte(x) | 0x80
+		x >>= 7
+		i++
+	}
+	p[i] = byte(x)
+	return i + 1
+}
+
+// errOverflow indicates an overflow of the 64-bit unsigned integer.
+var errOverflowU64 = errors.New("xz: uvarint overflows 64-bit unsigned integer")
+
+// readUvarint reads a uvarint from the given byte reader.
+func readUvarint(r io.ByteReader) (x uint64, n int, err error) {
+	var s uint
+	i := 0
+	for {
+		b, err := r.ReadByte()
+		if err != nil {
+			return x, i, err
+		}
+		i++
+		if b < 0x80 {
+			if i > 10 || i == 10 && b > 1 {
+				return x, i, errOverflowU64
+			}
+			return x | uint64(b)<<s, i, nil
+		}
+		x |= uint64(b&0x7f) << s
+		s += 7
+	}
+}
diff --git a/vendor/github.com/ulikunitz/xz/crc.go b/vendor/github.com/ulikunitz/xz/crc.go
new file mode 100644
index 000000000..b44dca96e
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/crc.go
@@ -0,0 +1,54 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xz
+
+import (
+	"hash"
+	"hash/crc32"
+	"hash/crc64"
+)
+
+// crc32Hash implements the hash.Hash32 interface with Sum returning the
+// crc32 value in little-endian encoding.
+type crc32Hash struct {
+	hash.Hash32
+}
+
+// Sum returns the crc32 value as little endian.
+func (h crc32Hash) Sum(b []byte) []byte {
+	p := make([]byte, 4)
+	putUint32LE(p, h.Hash32.Sum32())
+	b = append(b, p...)
+	return b
+}
+
+// newCRC32 returns a CRC-32 hash that returns the 64-bit value in
+// little-endian encoding using the IEEE polynomial.
+func newCRC32() hash.Hash {
+	return crc32Hash{Hash32: crc32.NewIEEE()}
+}
+
+// crc64Hash implements the Hash64 interface with Sum returning the
+// CRC-64 value in little-endian encoding.
+type crc64Hash struct {
+	hash.Hash64
+}
+
+// Sum returns the CRC-64 value in little-endian encoding.
+func (h crc64Hash) Sum(b []byte) []byte {
+	p := make([]byte, 8)
+	putUint64LE(p, h.Hash64.Sum64())
+	b = append(b, p...)
+	return b
+}
+
+// crc64Table is used to create a CRC-64 hash.
+var crc64Table = crc64.MakeTable(crc64.ECMA)
+
+// newCRC64 returns a CRC-64 hash that returns the 64-bit value in
+// little-endian encoding using the ECMA polynomial.
+func newCRC64() hash.Hash {
+	return crc64Hash{Hash64: crc64.New(crc64Table)}
+}
diff --git a/vendor/github.com/ulikunitz/xz/example.go b/vendor/github.com/ulikunitz/xz/example.go
new file mode 100644
index 000000000..855e60aee
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/example.go
@@ -0,0 +1,40 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package main
+
+import (
+	"bytes"
+	"io"
+	"log"
+	"os"
+
+	"github.com/ulikunitz/xz"
+)
+
+func main() {
+	const text = "The quick brown fox jumps over the lazy dog.\n"
+	var buf bytes.Buffer
+	// compress text
+	w, err := xz.NewWriter(&buf)
+	if err != nil {
+		log.Fatalf("xz.NewWriter error %s", err)
+	}
+	if _, err := io.WriteString(w, text); err != nil {
+		log.Fatalf("WriteString error %s", err)
+	}
+	if err := w.Close(); err != nil {
+		log.Fatalf("w.Close error %s", err)
+	}
+	// decompress buffer and write output to stdout
+	r, err := xz.NewReader(&buf)
+	if err != nil {
+		log.Fatalf("NewReader error %s", err)
+	}
+	if _, err = io.Copy(os.Stdout, r); err != nil {
+		log.Fatalf("io.Copy error %s", err)
+	}
+}
diff --git a/vendor/github.com/ulikunitz/xz/format.go b/vendor/github.com/ulikunitz/xz/format.go
new file mode 100644
index 000000000..798159c6c
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/format.go
@@ -0,0 +1,728 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xz
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"errors"
+	"fmt"
+	"hash"
+	"hash/crc32"
+	"io"
+
+	"github.com/ulikunitz/xz/lzma"
+)
+
+// allZeros checks whether a given byte slice has only zeros.
+func allZeros(p []byte) bool {
+	for _, c := range p {
+		if c != 0 {
+			return false
+		}
+	}
+	return true
+}
+
+// padLen returns the length of the padding required for the given
+// argument.
+func padLen(n int64) int {
+	k := int(n % 4)
+	if k > 0 {
+		k = 4 - k
+	}
+	return k
+}
+
+/*** Header ***/
+
+// headerMagic stores the magic bytes for the header
+var headerMagic = []byte{0xfd, '7', 'z', 'X', 'Z', 0x00}
+
+// HeaderLen provides the length of the xz file header.
+const HeaderLen = 12
+
+// Constants for the checksum methods supported by xz.
+const (
+	CRC32  byte = 0x1
+	CRC64       = 0x4
+	SHA256      = 0xa
+)
+
+// errInvalidFlags indicates that flags are invalid.
+var errInvalidFlags = errors.New("xz: invalid flags")
+
+// verifyFlags returns the error errInvalidFlags if the value is
+// invalid.
+func verifyFlags(flags byte) error {
+	switch flags {
+	case CRC32, CRC64, SHA256:
+		return nil
+	default:
+		return errInvalidFlags
+	}
+}
+
+// flagstrings maps flag values to strings.
+var flagstrings = map[byte]string{
+	CRC32:  "CRC-32",
+	CRC64:  "CRC-64",
+	SHA256: "SHA-256",
+}
+
+// flagString returns the string representation for the given flags.
+func flagString(flags byte) string {
+	s, ok := flagstrings[flags]
+	if !ok {
+		return "invalid"
+	}
+	return s
+}
+
+// newHashFunc returns a function that creates hash instances for the
+// hash method encoded in flags.
+func newHashFunc(flags byte) (newHash func() hash.Hash, err error) {
+	switch flags {
+	case CRC32:
+		newHash = newCRC32
+	case CRC64:
+		newHash = newCRC64
+	case SHA256:
+		newHash = sha256.New
+	default:
+		err = errInvalidFlags
+	}
+	return
+}
+
+// header provides the actual content of the xz file header: the flags.
+type header struct {
+	flags byte
+}
+
+// Errors returned by readHeader.
+var errHeaderMagic = errors.New("xz: invalid header magic bytes")
+
+// ValidHeader checks whether data is a correct xz file header. The
+// length of data must be HeaderLen.
+func ValidHeader(data []byte) bool {
+	var h header
+	err := h.UnmarshalBinary(data)
+	return err == nil
+}
+
+// String returns a string representation of the flags.
+func (h header) String() string {
+	return flagString(h.flags)
+}
+
+// UnmarshalBinary reads header from the provided data slice.
+func (h *header) UnmarshalBinary(data []byte) error {
+	// header length
+	if len(data) != HeaderLen {
+		return errors.New("xz: wrong file header length")
+	}
+
+	// magic header
+	if !bytes.Equal(headerMagic, data[:6]) {
+		return errHeaderMagic
+	}
+
+	// checksum
+	crc := crc32.NewIEEE()
+	crc.Write(data[6:8])
+	if uint32LE(data[8:]) != crc.Sum32() {
+		return errors.New("xz: invalid checksum for file header")
+	}
+
+	// stream flags
+	if data[6] != 0 {
+		return errInvalidFlags
+	}
+	flags := data[7]
+	if err := verifyFlags(flags); err != nil {
+		return err
+	}
+
+	h.flags = flags
+	return nil
+}
+
+// MarshalBinary generates the xz file header.
+func (h *header) MarshalBinary() (data []byte, err error) {
+	if err = verifyFlags(h.flags); err != nil {
+		return nil, err
+	}
+
+	data = make([]byte, 12)
+	copy(data, headerMagic)
+	data[7] = h.flags
+
+	crc := crc32.NewIEEE()
+	crc.Write(data[6:8])
+	putUint32LE(data[8:], crc.Sum32())
+
+	return data, nil
+}
+
+/*** Footer ***/
+
+// footerLen defines the length of the footer.
+const footerLen = 12
+
+// footerMagic contains the footer magic bytes.
+var footerMagic = []byte{'Y', 'Z'}
+
+// footer represents the content of the xz file footer.
+type footer struct {
+	indexSize int64
+	flags     byte
+}
+
+// String prints a string representation of the footer structure.
+func (f footer) String() string {
+	return fmt.Sprintf("%s index size %d", flagString(f.flags), f.indexSize)
+}
+
+// Minimum and maximum for the size of the index (backward size).
+const (
+	minIndexSize = 4
+	maxIndexSize = (1 << 32) * 4
+)
+
+// MarshalBinary converts footer values into an xz file footer. Note
+// that the footer value is checked for correctness.
+func (f *footer) MarshalBinary() (data []byte, err error) {
+	if err = verifyFlags(f.flags); err != nil {
+		return nil, err
+	}
+	if !(minIndexSize <= f.indexSize && f.indexSize <= maxIndexSize) {
+		return nil, errors.New("xz: index size out of range")
+	}
+	if f.indexSize%4 != 0 {
+		return nil, errors.New(
+			"xz: index size not aligned to four bytes")
+	}
+
+	data = make([]byte, footerLen)
+
+	// backward size (index size)
+	s := (f.indexSize / 4) - 1
+	putUint32LE(data[4:], uint32(s))
+	// flags
+	data[9] = f.flags
+	// footer magic
+	copy(data[10:], footerMagic)
+
+	// CRC-32
+	crc := crc32.NewIEEE()
+	crc.Write(data[4:10])
+	putUint32LE(data, crc.Sum32())
+
+	return data, nil
+}
+
+// UnmarshalBinary sets the footer value by unmarshalling an xz file
+// footer.
+func (f *footer) UnmarshalBinary(data []byte) error {
+	if len(data) != footerLen {
+		return errors.New("xz: wrong footer length")
+	}
+
+	// magic bytes
+	if !bytes.Equal(data[10:], footerMagic) {
+		return errors.New("xz: footer magic invalid")
+	}
+
+	// CRC-32
+	crc := crc32.NewIEEE()
+	crc.Write(data[4:10])
+	if uint32LE(data) != crc.Sum32() {
+		return errors.New("xz: footer checksum error")
+	}
+
+	var g footer
+	// backward size (index size)
+	g.indexSize = (int64(uint32LE(data[4:])) + 1) * 4
+
+	// flags
+	if data[8] != 0 {
+		return errInvalidFlags
+	}
+	g.flags = data[9]
+	if err := verifyFlags(g.flags); err != nil {
+		return err
+	}
+
+	*f = g
+	return nil
+}
+
+/*** Block Header ***/
+
+// blockHeader represents the content of an xz block header.
+type blockHeader struct {
+	compressedSize   int64
+	uncompressedSize int64
+	filters          []filter
+}
+
+// String converts the block header into a string.
+func (h blockHeader) String() string {
+	var buf bytes.Buffer
+	first := true
+	if h.compressedSize >= 0 {
+		fmt.Fprintf(&buf, "compressed size %d", h.compressedSize)
+		first = false
+	}
+	if h.uncompressedSize >= 0 {
+		if !first {
+			buf.WriteString(" ")
+		}
+		fmt.Fprintf(&buf, "uncompressed size %d", h.uncompressedSize)
+		first = false
+	}
+	for _, f := range h.filters {
+		if !first {
+			buf.WriteString(" ")
+		}
+		fmt.Fprintf(&buf, "filter %s", f)
+		first = false
+	}
+	return buf.String()
+}
+
+// Masks for the block flags.
+const (
+	filterCountMask         = 0x03
+	compressedSizePresent   = 0x40
+	uncompressedSizePresent = 0x80
+	reservedBlockFlags      = 0x3C
+)
+
+// errIndexIndicator signals that an index indicator (0x00) has been found
+// instead of an expected block header indicator.
+var errIndexIndicator = errors.New("xz: found index indicator")
+
+// readBlockHeader reads the block header.
+func readBlockHeader(r io.Reader) (h *blockHeader, n int, err error) {
+	var buf bytes.Buffer
+	buf.Grow(20)
+
+	// block header size
+	z, err := io.CopyN(&buf, r, 1)
+	n = int(z)
+	if err != nil {
+		return nil, n, err
+	}
+	s := buf.Bytes()[0]
+	if s == 0 {
+		return nil, n, errIndexIndicator
+	}
+
+	// read complete header
+	headerLen := (int(s) + 1) * 4
+	buf.Grow(headerLen - 1)
+	z, err = io.CopyN(&buf, r, int64(headerLen-1))
+	n += int(z)
+	if err != nil {
+		return nil, n, err
+	}
+
+	// unmarshal block header
+	h = new(blockHeader)
+	if err = h.UnmarshalBinary(buf.Bytes()); err != nil {
+		return nil, n, err
+	}
+
+	return h, n, nil
+}
+
+// readSizeInBlockHeader reads the uncompressed or compressed size
+// fields in the block header. The present value informs the function
+// whether the respective field is actually present in the header.
+func readSizeInBlockHeader(r io.ByteReader, present bool) (n int64, err error) {
+	if !present {
+		return -1, nil
+	}
+	x, _, err := readUvarint(r)
+	if err != nil {
+		return 0, err
+	}
+	if x >= 1<<63 {
+		return 0, errors.New("xz: size overflow in block header")
+	}
+	return int64(x), nil
+}
+
+// UnmarshalBinary unmarshals the block header.
+func (h *blockHeader) UnmarshalBinary(data []byte) error {
+	// Check header length
+	s := data[0]
+	if data[0] == 0 {
+		return errIndexIndicator
+	}
+	headerLen := (int(s) + 1) * 4
+	if len(data) != headerLen {
+		return fmt.Errorf("xz: data length %d; want %d", len(data),
+			headerLen)
+	}
+	n := headerLen - 4
+
+	// Check CRC-32
+	crc := crc32.NewIEEE()
+	crc.Write(data[:n])
+	if crc.Sum32() != uint32LE(data[n:]) {
+		return errors.New("xz: checksum error for block header")
+	}
+
+	// Block header flags
+	flags := data[1]
+	if flags&reservedBlockFlags != 0 {
+		return errors.New("xz: reserved block header flags set")
+	}
+
+	r := bytes.NewReader(data[2:n])
+
+	// Compressed size
+	var err error
+	h.compressedSize, err = readSizeInBlockHeader(
+		r, flags&compressedSizePresent != 0)
+	if err != nil {
+		return err
+	}
+
+	// Uncompressed size
+	h.uncompressedSize, err = readSizeInBlockHeader(
+		r, flags&uncompressedSizePresent != 0)
+	if err != nil {
+		return err
+	}
+
+	h.filters, err = readFilters(r, int(flags&filterCountMask)+1)
+	if err != nil {
+		return err
+	}
+
+	// Check padding
+	// Since headerLen is a multiple of 4 we don't need to check
+	// alignment.
+	k := r.Len()
+	// The standard spec says that the padding should have not more
+	// than 3 bytes. However we found paddings of 4 or 5 in the
+	// wild. See https://github.com/ulikunitz/xz/pull/11 and
+	// https://github.com/ulikunitz/xz/issues/15
+	//
+	// The only reasonable approach seems to be to ignore the
+	// padding size. We still check that all padding bytes are zero.
+	if !allZeros(data[n-k : n]) {
+		return errPadding
+	}
+	return nil
+}
+
+// MarshalBinary marshals the binary header.
+func (h *blockHeader) MarshalBinary() (data []byte, err error) {
+	if !(minFilters <= len(h.filters) && len(h.filters) <= maxFilters) {
+		return nil, errors.New("xz: filter count wrong")
+	}
+	for i, f := range h.filters {
+		if i < len(h.filters)-1 {
+			if f.id() == lzmaFilterID {
+				return nil, errors.New(
+					"xz: LZMA2 filter is not the last")
+			}
+		} else {
+			// last filter
+			if f.id() != lzmaFilterID {
+				return nil, errors.New("xz: " +
+					"last filter must be the LZMA2 filter")
+			}
+		}
+	}
+
+	var buf bytes.Buffer
+	// header size must set at the end
+	buf.WriteByte(0)
+
+	// flags
+	flags := byte(len(h.filters) - 1)
+	if h.compressedSize >= 0 {
+		flags |= compressedSizePresent
+	}
+	if h.uncompressedSize >= 0 {
+		flags |= uncompressedSizePresent
+	}
+	buf.WriteByte(flags)
+
+	p := make([]byte, 10)
+	if h.compressedSize >= 0 {
+		k := putUvarint(p, uint64(h.compressedSize))
+		buf.Write(p[:k])
+	}
+	if h.uncompressedSize >= 0 {
+		k := putUvarint(p, uint64(h.uncompressedSize))
+		buf.Write(p[:k])
+	}
+
+	for _, f := range h.filters {
+		fp, err := f.MarshalBinary()
+		if err != nil {
+			return nil, err
+		}
+		buf.Write(fp)
+	}
+
+	// padding
+	for i := padLen(int64(buf.Len())); i > 0; i-- {
+		buf.WriteByte(0)
+	}
+
+	// crc place holder
+	buf.Write(p[:4])
+
+	data = buf.Bytes()
+	if len(data)%4 != 0 {
+		panic("data length not aligned")
+	}
+	s := len(data)/4 - 1
+	if !(1 < s && s <= 255) {
+		panic("wrong block header size")
+	}
+	data[0] = byte(s)
+
+	crc := crc32.NewIEEE()
+	crc.Write(data[:len(data)-4])
+	putUint32LE(data[len(data)-4:], crc.Sum32())
+
+	return data, nil
+}
+
+// Constants used for marshalling and unmarshalling filters in the xz
+// block header.
+const (
+	minFilters    = 1
+	maxFilters    = 4
+	minReservedID = 1 << 62
+)
+
+// filter represents a filter in the block header.
+type filter interface {
+	id() uint64
+	UnmarshalBinary(data []byte) error
+	MarshalBinary() (data []byte, err error)
+	reader(r io.Reader, c *ReaderConfig) (fr io.Reader, err error)
+	writeCloser(w io.WriteCloser, c *WriterConfig) (fw io.WriteCloser, err error)
+	// filter must be last filter
+	last() bool
+}
+
+// readFilter reads a block filter from the block header. At this point
+// in time only the LZMA2 filter is supported.
+func readFilter(r io.Reader) (f filter, err error) {
+	br := lzma.ByteReader(r)
+
+	// index
+	id, _, err := readUvarint(br)
+	if err != nil {
+		return nil, err
+	}
+
+	var data []byte
+	switch id {
+	case lzmaFilterID:
+		data = make([]byte, lzmaFilterLen)
+		data[0] = lzmaFilterID
+		if _, err = io.ReadFull(r, data[1:]); err != nil {
+			return nil, err
+		}
+		f = new(lzmaFilter)
+	default:
+		if id >= minReservedID {
+			return nil, errors.New(
+				"xz: reserved filter id in block stream header")
+		}
+		return nil, errors.New("xz: invalid filter id")
+	}
+	if err = f.UnmarshalBinary(data); err != nil {
+		return nil, err
+	}
+	return f, err
+}
+
+// readFilters reads count filters. At this point in time only the count
+// 1 is supported.
+func readFilters(r io.Reader, count int) (filters []filter, err error) {
+	if count != 1 {
+		return nil, errors.New("xz: unsupported filter count")
+	}
+	f, err := readFilter(r)
+	if err != nil {
+		return nil, err
+	}
+	return []filter{f}, err
+}
+
+// writeFilters writes the filters.
+func writeFilters(w io.Writer, filters []filter) (n int, err error) {
+	for _, f := range filters {
+		p, err := f.MarshalBinary()
+		if err != nil {
+			return n, err
+		}
+		k, err := w.Write(p)
+		n += k
+		if err != nil {
+			return n, err
+		}
+	}
+	return n, nil
+}
+
+/*** Index ***/
+
+// record describes a block in the xz file index.
+type record struct {
+	unpaddedSize     int64
+	uncompressedSize int64
+}
+
+// readRecord reads an index record.
+func readRecord(r io.ByteReader) (rec record, n int, err error) {
+	u, k, err := readUvarint(r)
+	n += k
+	if err != nil {
+		return rec, n, err
+	}
+	rec.unpaddedSize = int64(u)
+	if rec.unpaddedSize < 0 {
+		return rec, n, errors.New("xz: unpadded size negative")
+	}
+
+	u, k, err = readUvarint(r)
+	n += k
+	if err != nil {
+		return rec, n, err
+	}
+	rec.uncompressedSize = int64(u)
+	if rec.uncompressedSize < 0 {
+		return rec, n, errors.New("xz: uncompressed size negative")
+	}
+
+	return rec, n, nil
+}
+
+// MarshalBinary converts an index record in its binary encoding.
+func (rec *record) MarshalBinary() (data []byte, err error) {
+	// maximum length of a uvarint is 10
+	p := make([]byte, 20)
+	n := putUvarint(p, uint64(rec.unpaddedSize))
+	n += putUvarint(p[n:], uint64(rec.uncompressedSize))
+	return p[:n], nil
+}
+
+// writeIndex writes the index, a sequence of records.
+func writeIndex(w io.Writer, index []record) (n int64, err error) {
+	crc := crc32.NewIEEE()
+	mw := io.MultiWriter(w, crc)
+
+	// index indicator
+	k, err := mw.Write([]byte{0})
+	n += int64(k)
+	if err != nil {
+		return n, err
+	}
+
+	// number of records
+	p := make([]byte, 10)
+	k = putUvarint(p, uint64(len(index)))
+	k, err = mw.Write(p[:k])
+	n += int64(k)
+	if err != nil {
+		return n, err
+	}
+
+	// list of records
+	for _, rec := range index {
+		p, err := rec.MarshalBinary()
+		if err != nil {
+			return n, err
+		}
+		k, err = mw.Write(p)
+		n += int64(k)
+		if err != nil {
+			return n, err
+		}
+	}
+
+	// index padding
+	k, err = mw.Write(make([]byte, padLen(int64(n))))
+	n += int64(k)
+	if err != nil {
+		return n, err
+	}
+
+	// crc32 checksum
+	putUint32LE(p, crc.Sum32())
+	k, err = w.Write(p[:4])
+	n += int64(k)
+
+	return n, err
+}
+
+// readIndexBody reads the index from the reader. It assumes that the
+// index indicator has already been read.
+func readIndexBody(r io.Reader) (records []record, n int64, err error) {
+	crc := crc32.NewIEEE()
+	// index indicator
+	crc.Write([]byte{0})
+
+	br := lzma.ByteReader(io.TeeReader(r, crc))
+
+	// number of records
+	u, k, err := readUvarint(br)
+	n += int64(k)
+	if err != nil {
+		return nil, n, err
+	}
+	recLen := int(u)
+	if recLen < 0 || uint64(recLen) != u {
+		return nil, n, errors.New("xz: record number overflow")
+	}
+
+	// list of records
+	records = make([]record, recLen)
+	for i := range records {
+		records[i], k, err = readRecord(br)
+		n += int64(k)
+		if err != nil {
+			return nil, n, err
+		}
+	}
+
+	p := make([]byte, padLen(int64(n+1)), 4)
+	k, err = io.ReadFull(br.(io.Reader), p)
+	n += int64(k)
+	if err != nil {
+		return nil, n, err
+	}
+	if !allZeros(p) {
+		return nil, n, errors.New("xz: non-zero byte in index padding")
+	}
+
+	// crc32
+	s := crc.Sum32()
+	p = p[:4]
+	k, err = io.ReadFull(br.(io.Reader), p)
+	n += int64(k)
+	if err != nil {
+		return records, n, err
+	}
+	if uint32LE(p) != s {
+		return nil, n, errors.New("xz: wrong checksum for index")
+	}
+
+	return records, n, nil
+}
diff --git a/vendor/github.com/ulikunitz/xz/internal/hash/cyclic_poly.go b/vendor/github.com/ulikunitz/xz/internal/hash/cyclic_poly.go
new file mode 100644
index 000000000..a32887872
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/internal/hash/cyclic_poly.go
@@ -0,0 +1,181 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package hash
+
+// CyclicPoly provides a cyclic polynomial rolling hash.
+type CyclicPoly struct {
+	h uint64
+	p []uint64
+	i int
+}
+
+// ror rotates the unsigned 64-bit integer to right. The argument s must be
+// less than 64.
+func ror(x uint64, s uint) uint64 {
+	return (x >> s) | (x << (64 - s))
+}
+
+// NewCyclicPoly creates a new instance of the CyclicPoly structure. The
+// argument n gives the number of bytes for which a hash will be executed.
+// This number must be positive; the method panics if this isn't the case.
+func NewCyclicPoly(n int) *CyclicPoly {
+	if n < 1 {
+		panic("argument n must be positive")
+	}
+	return &CyclicPoly{p: make([]uint64, 0, n)}
+}
+
+// Len returns the length of the byte sequence for which a hash is generated.
+func (r *CyclicPoly) Len() int {
+	return cap(r.p)
+}
+
+// RollByte hashes the next byte and returns a hash value. The complete becomes
+// available after at least Len() bytes have been hashed.
+func (r *CyclicPoly) RollByte(x byte) uint64 {
+	y := hash[x]
+	if len(r.p) < cap(r.p) {
+		r.h = ror(r.h, 1) ^ y
+		r.p = append(r.p, y)
+	} else {
+		r.h ^= ror(r.p[r.i], uint(cap(r.p)-1))
+		r.h = ror(r.h, 1) ^ y
+		r.p[r.i] = y
+		r.i = (r.i + 1) % cap(r.p)
+	}
+	return r.h
+}
+
+// Stores the hash for the individual bytes.
+var hash = [256]uint64{
+	0x2e4fc3f904065142, 0xc790984cfbc99527,
+	0x879f95eb8c62f187, 0x3b61be86b5021ef2,
+	0x65a896a04196f0a5, 0xc5b307b80470b59e,
+	0xd3bff376a70df14b, 0xc332f04f0b3f1701,
+	0x753b5f0e9abf3e0d, 0xb41538fdfe66ef53,
+	0x1906a10c2c1c0208, 0xfb0c712a03421c0d,
+	0x38be311a65c9552b, 0xfee7ee4ca6445c7e,
+	0x71aadeded184f21e, 0xd73426fccda23b2d,
+	0x29773fb5fb9600b5, 0xce410261cd32981a,
+	0xfe2848b3c62dbc2d, 0x459eaaff6e43e11c,
+	0xc13e35fc9c73a887, 0xf30ed5c201e76dbc,
+	0xa5f10b3910482cea, 0x2945d59be02dfaad,
+	0x06ee334ff70571b5, 0xbabf9d8070f44380,
+	0xee3e2e9912ffd27c, 0x2a7118d1ea6b8ea7,
+	0x26183cb9f7b1664c, 0xea71dac7da068f21,
+	0xea92eca5bd1d0bb7, 0x415595862defcd75,
+	0x248a386023c60648, 0x9cf021ab284b3c8a,
+	0xfc9372df02870f6c, 0x2b92d693eeb3b3fc,
+	0x73e799d139dc6975, 0x7b15ae312486363c,
+	0xb70e5454a2239c80, 0x208e3fb31d3b2263,
+	0x01f563cabb930f44, 0x2ac4533d2a3240d8,
+	0x84231ed1064f6f7c, 0xa9f020977c2a6d19,
+	0x213c227271c20122, 0x09fe8a9a0a03d07a,
+	0x4236dc75bcaf910c, 0x460a8b2bead8f17e,
+	0xd9b27be1aa07055f, 0xd202d5dc4b11c33e,
+	0x70adb010543bea12, 0xcdae938f7ea6f579,
+	0x3f3d870208672f4d, 0x8e6ccbce9d349536,
+	0xe4c0871a389095ae, 0xf5f2a49152bca080,
+	0x9a43f9b97269934e, 0xc17b3753cb6f475c,
+	0xd56d941e8e206bd4, 0xac0a4f3e525eda00,
+	0xa06d5a011912a550, 0x5537ed19537ad1df,
+	0xa32fe713d611449d, 0x2a1d05b47c3b579f,
+	0x991d02dbd30a2a52, 0x39e91e7e28f93eb0,
+	0x40d06adb3e92c9ac, 0x9b9d3afde1c77c97,
+	0x9a3f3f41c02c616f, 0x22ecd4ba00f60c44,
+	0x0b63d5d801708420, 0x8f227ca8f37ffaec,
+	0x0256278670887c24, 0x107e14877dbf540b,
+	0x32c19f2786ac1c05, 0x1df5b12bb4bc9c61,
+	0xc0cac129d0d4c4e2, 0x9fdb52ee9800b001,
+	0x31f601d5d31c48c4, 0x72ff3c0928bcaec7,
+	0xd99264421147eb03, 0x535a2d6d38aefcfe,
+	0x6ba8b4454a916237, 0xfa39366eaae4719c,
+	0x10f00fd7bbb24b6f, 0x5bd23185c76c84d4,
+	0xb22c3d7e1b00d33f, 0x3efc20aa6bc830a8,
+	0xd61c2503fe639144, 0x30ce625441eb92d3,
+	0xe5d34cf359e93100, 0xa8e5aa13f2b9f7a5,
+	0x5c2b8d851ca254a6, 0x68fb6c5e8b0d5fdf,
+	0xc7ea4872c96b83ae, 0x6dd5d376f4392382,
+	0x1be88681aaa9792f, 0xfef465ee1b6c10d9,
+	0x1f98b65ed43fcb2e, 0x4d1ca11eb6e9a9c9,
+	0x7808e902b3857d0b, 0x171c9c4ea4607972,
+	0x58d66274850146df, 0x42b311c10d3981d1,
+	0x647fa8c621c41a4c, 0xf472771c66ddfedc,
+	0x338d27e3f847b46b, 0x6402ce3da97545ce,
+	0x5162db616fc38638, 0x9c83be97bc22a50e,
+	0x2d3d7478a78d5e72, 0xe621a9b938fd5397,
+	0x9454614eb0f81c45, 0x395fb6e742ed39b6,
+	0x77dd9179d06037bf, 0xc478d0fee4d2656d,
+	0x35d9d6cb772007af, 0x83a56e92c883f0f6,
+	0x27937453250c00a1, 0x27bd6ebc3a46a97d,
+	0x9f543bf784342d51, 0xd158f38c48b0ed52,
+	0x8dd8537c045f66b4, 0x846a57230226f6d5,
+	0x6b13939e0c4e7cdf, 0xfca25425d8176758,
+	0x92e5fc6cd52788e6, 0x9992e13d7a739170,
+	0x518246f7a199e8ea, 0xf104c2a71b9979c7,
+	0x86b3ffaabea4768f, 0x6388061cf3e351ad,
+	0x09d9b5295de5bbb5, 0x38bf1638c2599e92,
+	0x1d759846499e148d, 0x4c0ff015e5f96ef4,
+	0xa41a94cfa270f565, 0x42d76f9cb2326c0b,
+	0x0cf385dd3c9c23ba, 0x0508a6c7508d6e7a,
+	0x337523aabbe6cf8d, 0x646bb14001d42b12,
+	0xc178729d138adc74, 0xf900ef4491f24086,
+	0xee1a90d334bb5ac4, 0x9755c92247301a50,
+	0xb999bf7c4ff1b610, 0x6aeeb2f3b21e8fc9,
+	0x0fa8084cf91ac6ff, 0x10d226cf136e6189,
+	0xd302057a07d4fb21, 0x5f03800e20a0fcc3,
+	0x80118d4ae46bd210, 0x58ab61a522843733,
+	0x51edd575c5432a4b, 0x94ee6ff67f9197f7,
+	0x765669e0e5e8157b, 0xa5347830737132f0,
+	0x3ba485a69f01510c, 0x0b247d7b957a01c3,
+	0x1b3d63449fd807dc, 0x0fdc4721c30ad743,
+	0x8b535ed3829b2b14, 0xee41d0cad65d232c,
+	0xe6a99ed97a6a982f, 0x65ac6194c202003d,
+	0x692accf3a70573eb, 0xcc3c02c3e200d5af,
+	0x0d419e8b325914a3, 0x320f160f42c25e40,
+	0x00710d647a51fe7a, 0x3c947692330aed60,
+	0x9288aa280d355a7a, 0xa1806a9b791d1696,
+	0x5d60e38496763da1, 0x6c69e22e613fd0f4,
+	0x977fc2a5aadffb17, 0xfb7bd063fc5a94ba,
+	0x460c17992cbaece1, 0xf7822c5444d3297f,
+	0x344a9790c69b74aa, 0xb80a42e6cae09dce,
+	0x1b1361eaf2b1e757, 0xd84c1e758e236f01,
+	0x88e0b7be347627cc, 0x45246009b7a99490,
+	0x8011c6dd3fe50472, 0xc341d682bffb99d7,
+	0x2511be93808e2d15, 0xd5bc13d7fd739840,
+	0x2a3cd030679ae1ec, 0x8ad9898a4b9ee157,
+	0x3245fef0a8eaf521, 0x3d6d8dbbb427d2b0,
+	0x1ed146d8968b3981, 0x0c6a28bf7d45f3fc,
+	0x4a1fd3dbcee3c561, 0x4210ff6a476bf67e,
+	0xa559cce0d9199aac, 0xde39d47ef3723380,
+	0xe5b69d848ce42e35, 0xefa24296f8e79f52,
+	0x70190b59db9a5afc, 0x26f166cdb211e7bf,
+	0x4deaf2df3c6b8ef5, 0xf171dbdd670f1017,
+	0xb9059b05e9420d90, 0x2f0da855c9388754,
+	0x611d5e9ab77949cc, 0x2912038ac01163f4,
+	0x0231df50402b2fba, 0x45660fc4f3245f58,
+	0xb91cc97c7c8dac50, 0xb72d2aafe4953427,
+	0xfa6463f87e813d6b, 0x4515f7ee95d5c6a2,
+	0x1310e1c1a48d21c3, 0xad48a7810cdd8544,
+	0x4d5bdfefd5c9e631, 0xa43ed43f1fdcb7de,
+	0xe70cfc8fe1ee9626, 0xef4711b0d8dda442,
+	0xb80dd9bd4dab6c93, 0xa23be08d31ba4d93,
+	0x9b37db9d0335a39c, 0x494b6f870f5cfebc,
+	0x6d1b3c1149dda943, 0x372c943a518c1093,
+	0xad27af45e77c09c4, 0x3b6f92b646044604,
+	0xac2917909f5fcf4f, 0x2069a60e977e5557,
+	0x353a469e71014de5, 0x24be356281f55c15,
+	0x2b6d710ba8e9adea, 0x404ad1751c749c29,
+	0xed7311bf23d7f185, 0xba4f6976b4acc43e,
+	0x32d7198d2bc39000, 0xee667019014d6e01,
+	0x494ef3e128d14c83, 0x1f95a152baecd6be,
+	0x201648dff1f483a5, 0x68c28550c8384af6,
+	0x5fc834a6824a7f48, 0x7cd06cb7365eaf28,
+	0xd82bbd95e9b30909, 0x234f0d1694c53f6d,
+	0xd2fb7f4a96d83f4a, 0xff0d5da83acac05e,
+	0xf8f6b97f5585080a, 0x74236084be57b95b,
+	0xa25e40c03bbc36ad, 0x6b6e5c14ce88465b,
+	0x4378ffe93e1528c5, 0x94ca92a17118e2d2,
+}
diff --git a/vendor/github.com/ulikunitz/xz/internal/hash/doc.go b/vendor/github.com/ulikunitz/xz/internal/hash/doc.go
new file mode 100644
index 000000000..f99ec2206
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/internal/hash/doc.go
@@ -0,0 +1,14 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package hash provides rolling hashes.
+
+Rolling hashes have to be used for maintaining the positions of n-byte
+sequences in the dictionary buffer.
+
+The package provides currently the Rabin-Karp rolling hash and a Cyclic
+Polynomial hash. Both support the Hashes method to be used with an interface.
+*/
+package hash
diff --git a/vendor/github.com/ulikunitz/xz/internal/hash/rabin_karp.go b/vendor/github.com/ulikunitz/xz/internal/hash/rabin_karp.go
new file mode 100644
index 000000000..58635b113
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/internal/hash/rabin_karp.go
@@ -0,0 +1,66 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package hash
+
+// A is the default constant for Robin-Karp rolling hash. This is a random
+// prime.
+const A = 0x97b548add41d5da1
+
+// RabinKarp supports the computation of a rolling hash.
+type RabinKarp struct {
+	A uint64
+	// a^n
+	aOldest uint64
+	h       uint64
+	p       []byte
+	i       int
+}
+
+// NewRabinKarp creates a new RabinKarp value. The argument n defines the
+// length of the byte sequence to be hashed. The default constant will will be
+// used.
+func NewRabinKarp(n int) *RabinKarp {
+	return NewRabinKarpConst(n, A)
+}
+
+// NewRabinKarpConst creates a new RabinKarp value. The argument n defines the
+// length of the byte sequence to be hashed. The argument a provides the
+// constant used to compute the hash.
+func NewRabinKarpConst(n int, a uint64) *RabinKarp {
+	if n <= 0 {
+		panic("number of bytes n must be positive")
+	}
+	aOldest := uint64(1)
+	// There are faster methods. For the small n required by the LZMA
+	// compressor O(n) is sufficient.
+	for i := 0; i < n; i++ {
+		aOldest *= a
+	}
+	return &RabinKarp{
+		A: a, aOldest: aOldest,
+		p: make([]byte, 0, n),
+	}
+}
+
+// Len returns the length of the byte sequence.
+func (r *RabinKarp) Len() int {
+	return cap(r.p)
+}
+
+// RollByte computes the hash after x has been added.
+func (r *RabinKarp) RollByte(x byte) uint64 {
+	if len(r.p) < cap(r.p) {
+		r.h += uint64(x)
+		r.h *= r.A
+		r.p = append(r.p, x)
+	} else {
+		r.h -= uint64(r.p[r.i]) * r.aOldest
+		r.h += uint64(x)
+		r.h *= r.A
+		r.p[r.i] = x
+		r.i = (r.i + 1) % cap(r.p)
+	}
+	return r.h
+}
diff --git a/vendor/github.com/ulikunitz/xz/internal/hash/roller.go b/vendor/github.com/ulikunitz/xz/internal/hash/roller.go
new file mode 100644
index 000000000..ab6a19ca4
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/internal/hash/roller.go
@@ -0,0 +1,29 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package hash
+
+// Roller provides an interface for rolling hashes. The hash value will become
+// valid after hash has been called Len times.
+type Roller interface {
+	Len() int
+	RollByte(x byte) uint64
+}
+
+// Hashes computes all hash values for the array p. Note that the state of the
+// roller is changed.
+func Hashes(r Roller, p []byte) []uint64 {
+	n := r.Len()
+	if len(p) < n {
+		return nil
+	}
+	h := make([]uint64, len(p)-n+1)
+	for i := 0; i < n-1; i++ {
+		r.RollByte(p[i])
+	}
+	for i := range h {
+		h[i] = r.RollByte(p[i+n-1])
+	}
+	return h
+}
diff --git a/vendor/github.com/ulikunitz/xz/internal/xlog/xlog.go b/vendor/github.com/ulikunitz/xz/internal/xlog/xlog.go
new file mode 100644
index 000000000..0ba45e8ff
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/internal/xlog/xlog.go
@@ -0,0 +1,457 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package xlog provides a simple logging package that allows to disable
+// certain message categories. It defines a type, Logger, with multiple
+// methods for formatting output. The package has also a predefined
+// 'standard' Logger accessible through helper function Print[f|ln],
+// Fatal[f|ln], Panic[f|ln], Warn[f|ln], Print[f|ln] and Debug[f|ln]
+// that are easier to use then creating a Logger manually. That logger
+// writes to standard error and prints the date and time of each logged
+// message, which can be configured using the function SetFlags.
+//
+// The Fatal functions call os.Exit(1) after the message is output
+// unless not suppressed by the flags. The Panic functions call panic
+// after the writing the log message unless suppressed.
+package xlog
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"runtime"
+	"sync"
+	"time"
+)
+
+// The flags define what information is prefixed to each log entry
+// generated by the Logger. The Lno* versions allow the suppression of
+// specific output. The bits are or'ed together to control what will be
+// printed. There is no control over the order of the items printed and
+// the format. The full format is:
+//
+//   2009-01-23 01:23:23.123123 /a/b/c/d.go:23: message
+//
+const (
+	Ldate         = 1 << iota // the date: 2009-01-23
+	Ltime                     // the time: 01:23:23
+	Lmicroseconds             // microsecond resolution: 01:23:23.123123
+	Llongfile                 // full file name and line number: /a/b/c/d.go:23
+	Lshortfile                // final file name element and line number: d.go:23
+	Lnopanic                  // suppresses output from Panic[f|ln] but not the panic call
+	Lnofatal                  // suppresses output from Fatal[f|ln] but not the exit
+	Lnowarn                   // suppresses output from Warn[f|ln]
+	Lnoprint                  // suppresses output from Print[f|ln]
+	Lnodebug                  // suppresses output from Debug[f|ln]
+	// initial values for the standard logger
+	Lstdflags = Ldate | Ltime | Lnodebug
+)
+
+// A Logger represents an active logging object that generates lines of
+// output to an io.Writer. Each logging operation if not suppressed
+// makes a single call to the Writer's Write method. A Logger can be
+// used simultaneously from multiple goroutines; it guarantees to
+// serialize access to the Writer.
+type Logger struct {
+	mu sync.Mutex // ensures atomic writes; and protects the following
+	// fields
+	prefix string    // prefix to write at beginning of each line
+	flag   int       // properties
+	out    io.Writer // destination for output
+	buf    []byte    // for accumulating text to write
+}
+
+// New creates a new Logger. The out argument sets the destination to
+// which the log output will be written. The prefix appears at the
+// beginning of each log line. The flag argument defines the logging
+// properties.
+func New(out io.Writer, prefix string, flag int) *Logger {
+	return &Logger{out: out, prefix: prefix, flag: flag}
+}
+
+// std is the standard logger used by the package scope functions.
+var std = New(os.Stderr, "", Lstdflags)
+
+// itoa converts the integer to ASCII. A negative widths will avoid
+// zero-padding. The function supports only non-negative integers.
+func itoa(buf *[]byte, i int, wid int) {
+	var u = uint(i)
+	if u == 0 && wid <= 1 {
+		*buf = append(*buf, '0')
+		return
+	}
+	var b [32]byte
+	bp := len(b)
+	for ; u > 0 || wid > 0; u /= 10 {
+		bp--
+		wid--
+		b[bp] = byte(u%10) + '0'
+	}
+	*buf = append(*buf, b[bp:]...)
+}
+
+// formatHeader puts the header into the buf field of the buffer.
+func (l *Logger) formatHeader(t time.Time, file string, line int) {
+	l.buf = append(l.buf, l.prefix...)
+	if l.flag&(Ldate|Ltime|Lmicroseconds) != 0 {
+		if l.flag&Ldate != 0 {
+			year, month, day := t.Date()
+			itoa(&l.buf, year, 4)
+			l.buf = append(l.buf, '-')
+			itoa(&l.buf, int(month), 2)
+			l.buf = append(l.buf, '-')
+			itoa(&l.buf, day, 2)
+			l.buf = append(l.buf, ' ')
+		}
+		if l.flag&(Ltime|Lmicroseconds) != 0 {
+			hour, min, sec := t.Clock()
+			itoa(&l.buf, hour, 2)
+			l.buf = append(l.buf, ':')
+			itoa(&l.buf, min, 2)
+			l.buf = append(l.buf, ':')
+			itoa(&l.buf, sec, 2)
+			if l.flag&Lmicroseconds != 0 {
+				l.buf = append(l.buf, '.')
+				itoa(&l.buf, t.Nanosecond()/1e3, 6)
+			}
+			l.buf = append(l.buf, ' ')
+		}
+	}
+	if l.flag&(Lshortfile|Llongfile) != 0 {
+		if l.flag&Lshortfile != 0 {
+			short := file
+			for i := len(file) - 1; i > 0; i-- {
+				if file[i] == '/' {
+					short = file[i+1:]
+					break
+				}
+			}
+			file = short
+		}
+		l.buf = append(l.buf, file...)
+		l.buf = append(l.buf, ':')
+		itoa(&l.buf, line, -1)
+		l.buf = append(l.buf, ": "...)
+	}
+}
+
+func (l *Logger) output(calldepth int, now time.Time, s string) error {
+	var file string
+	var line int
+	if l.flag&(Lshortfile|Llongfile) != 0 {
+		l.mu.Unlock()
+		var ok bool
+		_, file, line, ok = runtime.Caller(calldepth)
+		if !ok {
+			file = "???"
+			line = 0
+		}
+		l.mu.Lock()
+	}
+	l.buf = l.buf[:0]
+	l.formatHeader(now, file, line)
+	l.buf = append(l.buf, s...)
+	if len(s) == 0 || s[len(s)-1] != '\n' {
+		l.buf = append(l.buf, '\n')
+	}
+	_, err := l.out.Write(l.buf)
+	return err
+}
+
+// Output writes the string s with the header controlled by the flags to
+// the l.out writer. A newline will be appended if s doesn't end in a
+// newline. Calldepth is used to recover the PC, although all current
+// calls of Output use the call depth 2. Access to the function is serialized.
+func (l *Logger) Output(calldepth, noflag int, v ...interface{}) error {
+	now := time.Now()
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	if l.flag&noflag != 0 {
+		return nil
+	}
+	s := fmt.Sprint(v...)
+	return l.output(calldepth+1, now, s)
+}
+
+// Outputf works like output but formats the output like Printf.
+func (l *Logger) Outputf(calldepth int, noflag int, format string, v ...interface{}) error {
+	now := time.Now()
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	if l.flag&noflag != 0 {
+		return nil
+	}
+	s := fmt.Sprintf(format, v...)
+	return l.output(calldepth+1, now, s)
+}
+
+// Outputln works like output but formats the output like Println.
+func (l *Logger) Outputln(calldepth int, noflag int, v ...interface{}) error {
+	now := time.Now()
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	if l.flag&noflag != 0 {
+		return nil
+	}
+	s := fmt.Sprintln(v...)
+	return l.output(calldepth+1, now, s)
+}
+
+// Panic prints the message like Print and calls panic. The printing
+// might be suppressed by the flag Lnopanic.
+func (l *Logger) Panic(v ...interface{}) {
+	l.Output(2, Lnopanic, v...)
+	s := fmt.Sprint(v...)
+	panic(s)
+}
+
+// Panic prints the message like Print and calls panic. The printing
+// might be suppressed by the flag Lnopanic.
+func Panic(v ...interface{}) {
+	std.Output(2, Lnopanic, v...)
+	s := fmt.Sprint(v...)
+	panic(s)
+}
+
+// Panicf prints the message like Printf and calls panic. The printing
+// might be suppressed by the flag Lnopanic.
+func (l *Logger) Panicf(format string, v ...interface{}) {
+	l.Outputf(2, Lnopanic, format, v...)
+	s := fmt.Sprintf(format, v...)
+	panic(s)
+}
+
+// Panicf prints the message like Printf and calls panic. The printing
+// might be suppressed by the flag Lnopanic.
+func Panicf(format string, v ...interface{}) {
+	std.Outputf(2, Lnopanic, format, v...)
+	s := fmt.Sprintf(format, v...)
+	panic(s)
+}
+
+// Panicln prints the message like Println and calls panic. The printing
+// might be suppressed by the flag Lnopanic.
+func (l *Logger) Panicln(v ...interface{}) {
+	l.Outputln(2, Lnopanic, v...)
+	s := fmt.Sprintln(v...)
+	panic(s)
+}
+
+// Panicln prints the message like Println and calls panic. The printing
+// might be suppressed by the flag Lnopanic.
+func Panicln(v ...interface{}) {
+	std.Outputln(2, Lnopanic, v...)
+	s := fmt.Sprintln(v...)
+	panic(s)
+}
+
+// Fatal prints the message like Print and calls os.Exit(1). The
+// printing might be suppressed by the flag Lnofatal.
+func (l *Logger) Fatal(v ...interface{}) {
+	l.Output(2, Lnofatal, v...)
+	os.Exit(1)
+}
+
+// Fatal prints the message like Print and calls os.Exit(1). The
+// printing might be suppressed by the flag Lnofatal.
+func Fatal(v ...interface{}) {
+	std.Output(2, Lnofatal, v...)
+	os.Exit(1)
+}
+
+// Fatalf prints the message like Printf and calls os.Exit(1). The
+// printing might be suppressed by the flag Lnofatal.
+func (l *Logger) Fatalf(format string, v ...interface{}) {
+	l.Outputf(2, Lnofatal, format, v...)
+	os.Exit(1)
+}
+
+// Fatalf prints the message like Printf and calls os.Exit(1). The
+// printing might be suppressed by the flag Lnofatal.
+func Fatalf(format string, v ...interface{}) {
+	std.Outputf(2, Lnofatal, format, v...)
+	os.Exit(1)
+}
+
+// Fatalln prints the message like Println and calls os.Exit(1). The
+// printing might be suppressed by the flag Lnofatal.
+func (l *Logger) Fatalln(format string, v ...interface{}) {
+	l.Outputln(2, Lnofatal, v...)
+	os.Exit(1)
+}
+
+// Fatalln prints the message like Println and calls os.Exit(1). The
+// printing might be suppressed by the flag Lnofatal.
+func Fatalln(format string, v ...interface{}) {
+	std.Outputln(2, Lnofatal, v...)
+	os.Exit(1)
+}
+
+// Warn prints the message like Print. The printing might be suppressed
+// by the flag Lnowarn.
+func (l *Logger) Warn(v ...interface{}) {
+	l.Output(2, Lnowarn, v...)
+}
+
+// Warn prints the message like Print. The printing might be suppressed
+// by the flag Lnowarn.
+func Warn(v ...interface{}) {
+	std.Output(2, Lnowarn, v...)
+}
+
+// Warnf prints the message like Printf. The printing might be suppressed
+// by the flag Lnowarn.
+func (l *Logger) Warnf(format string, v ...interface{}) {
+	l.Outputf(2, Lnowarn, format, v...)
+}
+
+// Warnf prints the message like Printf. The printing might be suppressed
+// by the flag Lnowarn.
+func Warnf(format string, v ...interface{}) {
+	std.Outputf(2, Lnowarn, format, v...)
+}
+
+// Warnln prints the message like Println. The printing might be suppressed
+// by the flag Lnowarn.
+func (l *Logger) Warnln(v ...interface{}) {
+	l.Outputln(2, Lnowarn, v...)
+}
+
+// Warnln prints the message like Println. The printing might be suppressed
+// by the flag Lnowarn.
+func Warnln(v ...interface{}) {
+	std.Outputln(2, Lnowarn, v...)
+}
+
+// Print prints the message like fmt.Print. The printing might be suppressed
+// by the flag Lnoprint.
+func (l *Logger) Print(v ...interface{}) {
+	l.Output(2, Lnoprint, v...)
+}
+
+// Print prints the message like fmt.Print. The printing might be suppressed
+// by the flag Lnoprint.
+func Print(v ...interface{}) {
+	std.Output(2, Lnoprint, v...)
+}
+
+// Printf prints the message like fmt.Printf. The printing might be suppressed
+// by the flag Lnoprint.
+func (l *Logger) Printf(format string, v ...interface{}) {
+	l.Outputf(2, Lnoprint, format, v...)
+}
+
+// Printf prints the message like fmt.Printf. The printing might be suppressed
+// by the flag Lnoprint.
+func Printf(format string, v ...interface{}) {
+	std.Outputf(2, Lnoprint, format, v...)
+}
+
+// Println prints the message like fmt.Println. The printing might be
+// suppressed by the flag Lnoprint.
+func (l *Logger) Println(v ...interface{}) {
+	l.Outputln(2, Lnoprint, v...)
+}
+
+// Println prints the message like fmt.Println. The printing might be
+// suppressed by the flag Lnoprint.
+func Println(v ...interface{}) {
+	std.Outputln(2, Lnoprint, v...)
+}
+
+// Debug prints the message like Print. The printing might be suppressed
+// by the flag Lnodebug.
+func (l *Logger) Debug(v ...interface{}) {
+	l.Output(2, Lnodebug, v...)
+}
+
+// Debug prints the message like Print. The printing might be suppressed
+// by the flag Lnodebug.
+func Debug(v ...interface{}) {
+	std.Output(2, Lnodebug, v...)
+}
+
+// Debugf prints the message like Printf. The printing might be suppressed
+// by the flag Lnodebug.
+func (l *Logger) Debugf(format string, v ...interface{}) {
+	l.Outputf(2, Lnodebug, format, v...)
+}
+
+// Debugf prints the message like Printf. The printing might be suppressed
+// by the flag Lnodebug.
+func Debugf(format string, v ...interface{}) {
+	std.Outputf(2, Lnodebug, format, v...)
+}
+
+// Debugln prints the message like Println. The printing might be suppressed
+// by the flag Lnodebug.
+func (l *Logger) Debugln(v ...interface{}) {
+	l.Outputln(2, Lnodebug, v...)
+}
+
+// Debugln prints the message like Println. The printing might be suppressed
+// by the flag Lnodebug.
+func Debugln(v ...interface{}) {
+	std.Outputln(2, Lnodebug, v...)
+}
+
+// Flags returns the current flags used by the logger.
+func (l *Logger) Flags() int {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	return l.flag
+}
+
+// Flags returns the current flags used by the standard logger.
+func Flags() int {
+	return std.Flags()
+}
+
+// SetFlags sets the flags of the logger.
+func (l *Logger) SetFlags(flag int) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.flag = flag
+}
+
+// SetFlags sets the flags for the standard logger.
+func SetFlags(flag int) {
+	std.SetFlags(flag)
+}
+
+// Prefix returns the prefix used by the logger.
+func (l *Logger) Prefix() string {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	return l.prefix
+}
+
+// Prefix returns the prefix used by the standard logger of the package.
+func Prefix() string {
+	return std.Prefix()
+}
+
+// SetPrefix sets the prefix for the logger.
+func (l *Logger) SetPrefix(prefix string) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.prefix = prefix
+}
+
+// SetPrefix sets the prefix of the standard logger of the package.
+func SetPrefix(prefix string) {
+	std.SetPrefix(prefix)
+}
+
+// SetOutput sets the output of the logger.
+func (l *Logger) SetOutput(w io.Writer) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.out = w
+}
+
+// SetOutput sets the output for the standard logger of the package.
+func SetOutput(w io.Writer) {
+	std.SetOutput(w)
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/bintree.go b/vendor/github.com/ulikunitz/xz/lzma/bintree.go
new file mode 100644
index 000000000..a781bd195
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/bintree.go
@@ -0,0 +1,523 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"unicode"
+)
+
+// node represents a node in the binary tree.
+type node struct {
+	// x is the search value
+	x uint32
+	// p parent node
+	p uint32
+	// l left child
+	l uint32
+	// r right child
+	r uint32
+}
+
+// wordLen is the number of bytes represented by the v field of a node.
+const wordLen = 4
+
+// binTree supports the identification of the next operation based on a
+// binary tree.
+//
+// Nodes will be identified by their index into the ring buffer.
+type binTree struct {
+	dict *encoderDict
+	// ring buffer of nodes
+	node []node
+	// absolute offset of the entry for the next node. Position 4
+	// byte larger.
+	hoff int64
+	// front position in the node ring buffer
+	front uint32
+	// index of the root node
+	root uint32
+	// current x value
+	x uint32
+	// preallocated array
+	data []byte
+}
+
+// null represents the nonexistent index. We can't use zero because it
+// would always exist or we would need to decrease the index for each
+// reference.
+const null uint32 = 1<<32 - 1
+
+// newBinTree initializes the binTree structure. The capacity defines
+// the size of the buffer and defines the maximum distance for which
+// matches will be found.
+func newBinTree(capacity int) (t *binTree, err error) {
+	if capacity < 1 {
+		return nil, errors.New(
+			"newBinTree: capacity must be larger than zero")
+	}
+	if int64(capacity) >= int64(null) {
+		return nil, errors.New(
+			"newBinTree: capacity must less 2^{32}-1")
+	}
+	t = &binTree{
+		node: make([]node, capacity),
+		hoff: -int64(wordLen),
+		root: null,
+		data: make([]byte, maxMatchLen),
+	}
+	return t, nil
+}
+
+func (t *binTree) SetDict(d *encoderDict) { t.dict = d }
+
+// WriteByte writes a single byte into the binary tree.
+func (t *binTree) WriteByte(c byte) error {
+	t.x = (t.x << 8) | uint32(c)
+	t.hoff++
+	if t.hoff < 0 {
+		return nil
+	}
+	v := t.front
+	if int64(v) < t.hoff {
+		// We are overwriting old nodes stored in the tree.
+		t.remove(v)
+	}
+	t.node[v].x = t.x
+	t.add(v)
+	t.front++
+	if int64(t.front) >= int64(len(t.node)) {
+		t.front = 0
+	}
+	return nil
+}
+
+// Writes writes a sequence of bytes into the binTree structure.
+func (t *binTree) Write(p []byte) (n int, err error) {
+	for _, c := range p {
+		t.WriteByte(c)
+	}
+	return len(p), nil
+}
+
+// add puts the node v into the tree. The node must not be part of the
+// tree before.
+func (t *binTree) add(v uint32) {
+	vn := &t.node[v]
+	// Set left and right to null indices.
+	vn.l, vn.r = null, null
+	// If the binary tree is empty make v the root.
+	if t.root == null {
+		t.root = v
+		vn.p = null
+		return
+	}
+	x := vn.x
+	p := t.root
+	// Search for the right leave link and add the new node.
+	for {
+		pn := &t.node[p]
+		if x <= pn.x {
+			if pn.l == null {
+				pn.l = v
+				vn.p = p
+				return
+			}
+			p = pn.l
+		} else {
+			if pn.r == null {
+				pn.r = v
+				vn.p = p
+				return
+			}
+			p = pn.r
+		}
+	}
+}
+
+// parent returns the parent node index of v and the pointer to v value
+// in the parent.
+func (t *binTree) parent(v uint32) (p uint32, ptr *uint32) {
+	if t.root == v {
+		return null, &t.root
+	}
+	p = t.node[v].p
+	if t.node[p].l == v {
+		ptr = &t.node[p].l
+	} else {
+		ptr = &t.node[p].r
+	}
+	return
+}
+
+// Remove node v.
+func (t *binTree) remove(v uint32) {
+	vn := &t.node[v]
+	p, ptr := t.parent(v)
+	l, r := vn.l, vn.r
+	if l == null {
+		// Move the right child up.
+		*ptr = r
+		if r != null {
+			t.node[r].p = p
+		}
+		return
+	}
+	if r == null {
+		// Move the left child up.
+		*ptr = l
+		t.node[l].p = p
+		return
+	}
+
+	// Search the in-order predecessor u.
+	un := &t.node[l]
+	ur := un.r
+	if ur == null {
+		// In order predecessor is l. Move it up.
+		un.r = r
+		t.node[r].p = l
+		un.p = p
+		*ptr = l
+		return
+	}
+	var u uint32
+	for {
+		// Look for the max value in the tree where l is root.
+		u = ur
+		ur = t.node[u].r
+		if ur == null {
+			break
+		}
+	}
+	// replace u with ul
+	un = &t.node[u]
+	ul := un.l
+	up := un.p
+	t.node[up].r = ul
+	if ul != null {
+		t.node[ul].p = up
+	}
+
+	// replace v by u
+	un.l, un.r = l, r
+	t.node[l].p = u
+	t.node[r].p = u
+	*ptr = u
+	un.p = p
+}
+
+// search looks for the node that have the value x or for the nodes that
+// brace it. The node highest in the tree with the value x will be
+// returned. All other nodes with the same value live in left subtree of
+// the returned node.
+func (t *binTree) search(v uint32, x uint32) (a, b uint32) {
+	a, b = null, null
+	if v == null {
+		return
+	}
+	for {
+		vn := &t.node[v]
+		if x <= vn.x {
+			if x == vn.x {
+				return v, v
+			}
+			b = v
+			if vn.l == null {
+				return
+			}
+			v = vn.l
+		} else {
+			a = v
+			if vn.r == null {
+				return
+			}
+			v = vn.r
+		}
+	}
+}
+
+// max returns the node with maximum value in the subtree with v as
+// root.
+func (t *binTree) max(v uint32) uint32 {
+	if v == null {
+		return null
+	}
+	for {
+		r := t.node[v].r
+		if r == null {
+			return v
+		}
+		v = r
+	}
+}
+
+// min returns the node with the minimum value in the subtree with v as
+// root.
+func (t *binTree) min(v uint32) uint32 {
+	if v == null {
+		return null
+	}
+	for {
+		l := t.node[v].l
+		if l == null {
+			return v
+		}
+		v = l
+	}
+}
+
+// pred returns the in-order predecessor of node v.
+func (t *binTree) pred(v uint32) uint32 {
+	if v == null {
+		return null
+	}
+	u := t.max(t.node[v].l)
+	if u != null {
+		return u
+	}
+	for {
+		p := t.node[v].p
+		if p == null {
+			return null
+		}
+		if t.node[p].r == v {
+			return p
+		}
+		v = p
+	}
+}
+
+// succ returns the in-order successor of node v.
+func (t *binTree) succ(v uint32) uint32 {
+	if v == null {
+		return null
+	}
+	u := t.min(t.node[v].r)
+	if u != null {
+		return u
+	}
+	for {
+		p := t.node[v].p
+		if p == null {
+			return null
+		}
+		if t.node[p].l == v {
+			return p
+		}
+		v = p
+	}
+}
+
+// xval converts the first four bytes of a into an 32-bit unsigned
+// integer in big-endian order.
+func xval(a []byte) uint32 {
+	var x uint32
+	switch len(a) {
+	default:
+		x |= uint32(a[3])
+		fallthrough
+	case 3:
+		x |= uint32(a[2]) << 8
+		fallthrough
+	case 2:
+		x |= uint32(a[1]) << 16
+		fallthrough
+	case 1:
+		x |= uint32(a[0]) << 24
+	case 0:
+	}
+	return x
+}
+
+// dumpX converts value x into a four-letter string.
+func dumpX(x uint32) string {
+	a := make([]byte, 4)
+	for i := 0; i < 4; i++ {
+		c := byte(x >> uint((3-i)*8))
+		if unicode.IsGraphic(rune(c)) {
+			a[i] = c
+		} else {
+			a[i] = '.'
+		}
+	}
+	return string(a)
+}
+
+// dumpNode writes a representation of the node v into the io.Writer.
+func (t *binTree) dumpNode(w io.Writer, v uint32, indent int) {
+	if v == null {
+		return
+	}
+
+	vn := &t.node[v]
+
+	t.dumpNode(w, vn.r, indent+2)
+
+	for i := 0; i < indent; i++ {
+		fmt.Fprint(w, " ")
+	}
+	if vn.p == null {
+		fmt.Fprintf(w, "node %d %q parent null\n", v, dumpX(vn.x))
+	} else {
+		fmt.Fprintf(w, "node %d %q parent %d\n", v, dumpX(vn.x), vn.p)
+	}
+
+	t.dumpNode(w, vn.l, indent+2)
+}
+
+// dump prints a representation of the binary tree into the writer.
+func (t *binTree) dump(w io.Writer) error {
+	bw := bufio.NewWriter(w)
+	t.dumpNode(bw, t.root, 0)
+	return bw.Flush()
+}
+
+func (t *binTree) distance(v uint32) int {
+	dist := int(t.front) - int(v)
+	if dist <= 0 {
+		dist += len(t.node)
+	}
+	return dist
+}
+
+type matchParams struct {
+	rep [4]uint32
+	// length when match will be accepted
+	nAccept int
+	// nodes to check
+	check int
+	// finish if length get shorter
+	stopShorter bool
+}
+
+func (t *binTree) match(m match, distIter func() (int, bool), p matchParams,
+) (r match, checked int, accepted bool) {
+	buf := &t.dict.buf
+	for {
+		if checked >= p.check {
+			return m, checked, true
+		}
+		dist, ok := distIter()
+		if !ok {
+			return m, checked, false
+		}
+		checked++
+		if m.n > 0 {
+			i := buf.rear - dist + m.n - 1
+			if i < 0 {
+				i += len(buf.data)
+			} else if i >= len(buf.data) {
+				i -= len(buf.data)
+			}
+			if buf.data[i] != t.data[m.n-1] {
+				if p.stopShorter {
+					return m, checked, false
+				}
+				continue
+			}
+		}
+		n := buf.matchLen(dist, t.data)
+		switch n {
+		case 0:
+			if p.stopShorter {
+				return m, checked, false
+			}
+			continue
+		case 1:
+			if uint32(dist-minDistance) != p.rep[0] {
+				continue
+			}
+		}
+		if n < m.n || (n == m.n && int64(dist) >= m.distance) {
+			continue
+		}
+		m = match{int64(dist), n}
+		if n >= p.nAccept {
+			return m, checked, true
+		}
+	}
+}
+
+func (t *binTree) NextOp(rep [4]uint32) operation {
+	// retrieve maxMatchLen data
+	n, _ := t.dict.buf.Peek(t.data[:maxMatchLen])
+	if n == 0 {
+		panic("no data in buffer")
+	}
+	t.data = t.data[:n]
+
+	var (
+		m                  match
+		x, u, v            uint32
+		iterPred, iterSucc func() (int, bool)
+	)
+	p := matchParams{
+		rep:     rep,
+		nAccept: maxMatchLen,
+		check:   32,
+	}
+	i := 4
+	iterSmall := func() (dist int, ok bool) {
+		i--
+		if i <= 0 {
+			return 0, false
+		}
+		return i, true
+	}
+	m, checked, accepted := t.match(m, iterSmall, p)
+	if accepted {
+		goto end
+	}
+	p.check -= checked
+	x = xval(t.data)
+	u, v = t.search(t.root, x)
+	if u == v && len(t.data) == 4 {
+		iter := func() (dist int, ok bool) {
+			if u == null {
+				return 0, false
+			}
+			dist = t.distance(u)
+			u, v = t.search(t.node[u].l, x)
+			if u != v {
+				u = null
+			}
+			return dist, true
+		}
+		m, _, _ = t.match(m, iter, p)
+		goto end
+	}
+	p.stopShorter = true
+	iterSucc = func() (dist int, ok bool) {
+		if v == null {
+			return 0, false
+		}
+		dist = t.distance(v)
+		v = t.succ(v)
+		return dist, true
+	}
+	m, checked, accepted = t.match(m, iterSucc, p)
+	if accepted {
+		goto end
+	}
+	p.check -= checked
+	iterPred = func() (dist int, ok bool) {
+		if u == null {
+			return 0, false
+		}
+		dist = t.distance(u)
+		u = t.pred(u)
+		return dist, true
+	}
+	m, _, _ = t.match(m, iterPred, p)
+end:
+	if m.n == 0 {
+		return lit{t.data[0]}
+	}
+	return m
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/bitops.go b/vendor/github.com/ulikunitz/xz/lzma/bitops.go
new file mode 100644
index 000000000..e9bab0199
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/bitops.go
@@ -0,0 +1,45 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+/* Naming conventions follows the CodeReviewComments in the Go Wiki. */
+
+// ntz32Const is used by the functions NTZ and NLZ.
+const ntz32Const = 0x04d7651f
+
+// ntz32Table is a helper table for de Bruijn algorithm by Danny Dubé.
+// See Henry S. Warren, Jr. "Hacker's Delight" section 5-1 figure 5-26.
+var ntz32Table = [32]int8{
+	0, 1, 2, 24, 3, 19, 6, 25,
+	22, 4, 20, 10, 16, 7, 12, 26,
+	31, 23, 18, 5, 21, 9, 15, 11,
+	30, 17, 8, 14, 29, 13, 28, 27,
+}
+
+// ntz32 computes the number of trailing zeros for an unsigned 32-bit integer.
+func ntz32(x uint32) int {
+	if x == 0 {
+		return 32
+	}
+	x = (x & -x) * ntz32Const
+	return int(ntz32Table[x>>27])
+}
+
+// nlz32 computes the number of leading zeros for an unsigned 32-bit integer.
+func nlz32(x uint32) int {
+	// Smear left most bit to the right
+	x |= x >> 1
+	x |= x >> 2
+	x |= x >> 4
+	x |= x >> 8
+	x |= x >> 16
+	// Use ntz mechanism to calculate nlz.
+	x++
+	if x == 0 {
+		return 0
+	}
+	x *= ntz32Const
+	return 32 - int(ntz32Table[x>>27])
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/breader.go b/vendor/github.com/ulikunitz/xz/lzma/breader.go
new file mode 100644
index 000000000..5350d814f
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/breader.go
@@ -0,0 +1,39 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"io"
+)
+
+// breader provides the ReadByte function for a Reader. It doesn't read
+// more data from the reader than absolutely necessary.
+type breader struct {
+	io.Reader
+	// helper slice to save allocations
+	p []byte
+}
+
+// ByteReader converts an io.Reader into an io.ByteReader.
+func ByteReader(r io.Reader) io.ByteReader {
+	br, ok := r.(io.ByteReader)
+	if !ok {
+		return &breader{r, make([]byte, 1)}
+	}
+	return br
+}
+
+// ReadByte read byte function.
+func (r *breader) ReadByte() (c byte, err error) {
+	n, err := r.Reader.Read(r.p)
+	if n < 1 {
+		if err == nil {
+			err = errors.New("breader.ReadByte: no data")
+		}
+		return 0, err
+	}
+	return r.p[0], nil
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/buffer.go b/vendor/github.com/ulikunitz/xz/lzma/buffer.go
new file mode 100644
index 000000000..50e0b6d57
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/buffer.go
@@ -0,0 +1,171 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+)
+
+// buffer provides a circular buffer of bytes. If the front index equals
+// the rear index the buffer is empty. As a consequence front cannot be
+// equal rear for a full buffer. So a full buffer has a length that is
+// one byte less the the length of the data slice.
+type buffer struct {
+	data  []byte
+	front int
+	rear  int
+}
+
+// newBuffer creates a buffer with the given size.
+func newBuffer(size int) *buffer {
+	return &buffer{data: make([]byte, size+1)}
+}
+
+// Cap returns the capacity of the buffer.
+func (b *buffer) Cap() int {
+	return len(b.data) - 1
+}
+
+// Resets the buffer. The front and rear index are set to zero.
+func (b *buffer) Reset() {
+	b.front = 0
+	b.rear = 0
+}
+
+// Buffered returns the number of bytes buffered.
+func (b *buffer) Buffered() int {
+	delta := b.front - b.rear
+	if delta < 0 {
+		delta += len(b.data)
+	}
+	return delta
+}
+
+// Available returns the number of bytes available for writing.
+func (b *buffer) Available() int {
+	delta := b.rear - 1 - b.front
+	if delta < 0 {
+		delta += len(b.data)
+	}
+	return delta
+}
+
+// addIndex adds a non-negative integer to the index i and returns the
+// resulting index. The function takes care of wrapping the index as
+// well as potential overflow situations.
+func (b *buffer) addIndex(i int, n int) int {
+	// subtraction of len(b.data) prevents overflow
+	i += n - len(b.data)
+	if i < 0 {
+		i += len(b.data)
+	}
+	return i
+}
+
+// Read reads bytes from the buffer into p and returns the number of
+// bytes read. The function never returns an error but might return less
+// data than requested.
+func (b *buffer) Read(p []byte) (n int, err error) {
+	n, err = b.Peek(p)
+	b.rear = b.addIndex(b.rear, n)
+	return n, err
+}
+
+// Peek reads bytes from the buffer into p without changing the buffer.
+// Peek will never return an error but might return less data than
+// requested.
+func (b *buffer) Peek(p []byte) (n int, err error) {
+	m := b.Buffered()
+	n = len(p)
+	if m < n {
+		n = m
+		p = p[:n]
+	}
+	k := copy(p, b.data[b.rear:])
+	if k < n {
+		copy(p[k:], b.data)
+	}
+	return n, nil
+}
+
+// Discard skips the n next bytes to read from the buffer, returning the
+// bytes discarded.
+//
+// If Discards skips fewer than n bytes, it returns an error.
+func (b *buffer) Discard(n int) (discarded int, err error) {
+	if n < 0 {
+		return 0, errors.New("buffer.Discard: negative argument")
+	}
+	m := b.Buffered()
+	if m < n {
+		n = m
+		err = errors.New(
+			"buffer.Discard: discarded less bytes then requested")
+	}
+	b.rear = b.addIndex(b.rear, n)
+	return n, err
+}
+
+// ErrNoSpace indicates that there is insufficient space for the Write
+// operation.
+var ErrNoSpace = errors.New("insufficient space")
+
+// Write puts data into the  buffer. If less bytes are written than
+// requested ErrNoSpace is returned.
+func (b *buffer) Write(p []byte) (n int, err error) {
+	m := b.Available()
+	n = len(p)
+	if m < n {
+		n = m
+		p = p[:m]
+		err = ErrNoSpace
+	}
+	k := copy(b.data[b.front:], p)
+	if k < n {
+		copy(b.data, p[k:])
+	}
+	b.front = b.addIndex(b.front, n)
+	return n, err
+}
+
+// WriteByte writes a single byte into the buffer. The error ErrNoSpace
+// is returned if no single byte is available in the buffer for writing.
+func (b *buffer) WriteByte(c byte) error {
+	if b.Available() < 1 {
+		return ErrNoSpace
+	}
+	b.data[b.front] = c
+	b.front = b.addIndex(b.front, 1)
+	return nil
+}
+
+// prefixLen returns the length of the common prefix of a and b.
+func prefixLen(a, b []byte) int {
+	if len(a) > len(b) {
+		a, b = b, a
+	}
+	for i, c := range a {
+		if b[i] != c {
+			return i
+		}
+	}
+	return len(a)
+}
+
+// matchLen returns the length of the common prefix for the given
+// distance from the rear and the byte slice p.
+func (b *buffer) matchLen(distance int, p []byte) int {
+	var n int
+	i := b.rear - distance
+	if i < 0 {
+		if n = prefixLen(p, b.data[len(b.data)+i:]); n < -i {
+			return n
+		}
+		p = p[n:]
+		i = 0
+	}
+	n += prefixLen(p, b.data[i:])
+	return n
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/bytewriter.go b/vendor/github.com/ulikunitz/xz/lzma/bytewriter.go
new file mode 100644
index 000000000..a3696ba08
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/bytewriter.go
@@ -0,0 +1,37 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"io"
+)
+
+// ErrLimit indicates that the limit of the LimitedByteWriter has been
+// reached.
+var ErrLimit = errors.New("limit reached")
+
+// LimitedByteWriter provides a byte writer that can be written until a
+// limit is reached. The field N provides the number of remaining
+// bytes.
+type LimitedByteWriter struct {
+	BW io.ByteWriter
+	N  int64
+}
+
+// WriteByte writes a single byte to the limited byte writer. It returns
+// ErrLimit if the limit has been reached. If the byte is successfully
+// written the field N of the LimitedByteWriter will be decremented by
+// one.
+func (l *LimitedByteWriter) WriteByte(c byte) error {
+	if l.N <= 0 {
+		return ErrLimit
+	}
+	if err := l.BW.WriteByte(c); err != nil {
+		return err
+	}
+	l.N--
+	return nil
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/decoder.go b/vendor/github.com/ulikunitz/xz/lzma/decoder.go
new file mode 100644
index 000000000..16e14db39
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/decoder.go
@@ -0,0 +1,277 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"fmt"
+	"io"
+)
+
+// decoder decodes a raw LZMA stream without any header.
+type decoder struct {
+	// dictionary; the rear pointer of the buffer will be used for
+	// reading the data.
+	Dict *decoderDict
+	// decoder state
+	State *state
+	// range decoder
+	rd *rangeDecoder
+	// start stores the head value of the dictionary for the LZMA
+	// stream
+	start int64
+	// size of uncompressed data
+	size int64
+	// end-of-stream encountered
+	eos bool
+	// EOS marker found
+	eosMarker bool
+}
+
+// newDecoder creates a new decoder instance. The parameter size provides
+// the expected byte size of the decompressed data. If the size is
+// unknown use a negative value. In that case the decoder will look for
+// a terminating end-of-stream marker.
+func newDecoder(br io.ByteReader, state *state, dict *decoderDict, size int64) (d *decoder, err error) {
+	rd, err := newRangeDecoder(br)
+	if err != nil {
+		return nil, err
+	}
+	d = &decoder{
+		State: state,
+		Dict:  dict,
+		rd:    rd,
+		size:  size,
+		start: dict.pos(),
+	}
+	return d, nil
+}
+
+// Reopen restarts the decoder with a new byte reader and a new size. Reopen
+// resets the Decompressed counter to zero.
+func (d *decoder) Reopen(br io.ByteReader, size int64) error {
+	var err error
+	if d.rd, err = newRangeDecoder(br); err != nil {
+		return err
+	}
+	d.start = d.Dict.pos()
+	d.size = size
+	d.eos = false
+	return nil
+}
+
+// decodeLiteral decodes a single literal from the LZMA stream.
+func (d *decoder) decodeLiteral() (op operation, err error) {
+	litState := d.State.litState(d.Dict.byteAt(1), d.Dict.head)
+	match := d.Dict.byteAt(int(d.State.rep[0]) + 1)
+	s, err := d.State.litCodec.Decode(d.rd, d.State.state, match, litState)
+	if err != nil {
+		return nil, err
+	}
+	return lit{s}, nil
+}
+
+// errEOS indicates that an EOS marker has been found.
+var errEOS = errors.New("EOS marker found")
+
+// readOp decodes the next operation from the compressed stream. It
+// returns the operation. If an explicit end of stream marker is
+// identified the eos error is returned.
+func (d *decoder) readOp() (op operation, err error) {
+	// Value of the end of stream (EOS) marker
+	const eosDist = 1<<32 - 1
+
+	state, state2, posState := d.State.states(d.Dict.head)
+
+	b, err := d.State.isMatch[state2].Decode(d.rd)
+	if err != nil {
+		return nil, err
+	}
+	if b == 0 {
+		// literal
+		op, err := d.decodeLiteral()
+		if err != nil {
+			return nil, err
+		}
+		d.State.updateStateLiteral()
+		return op, nil
+	}
+	b, err = d.State.isRep[state].Decode(d.rd)
+	if err != nil {
+		return nil, err
+	}
+	if b == 0 {
+		// simple match
+		d.State.rep[3], d.State.rep[2], d.State.rep[1] =
+			d.State.rep[2], d.State.rep[1], d.State.rep[0]
+
+		d.State.updateStateMatch()
+		// The length decoder returns the length offset.
+		n, err := d.State.lenCodec.Decode(d.rd, posState)
+		if err != nil {
+			return nil, err
+		}
+		// The dist decoder returns the distance offset. The actual
+		// distance is 1 higher.
+		d.State.rep[0], err = d.State.distCodec.Decode(d.rd, n)
+		if err != nil {
+			return nil, err
+		}
+		if d.State.rep[0] == eosDist {
+			d.eosMarker = true
+			return nil, errEOS
+		}
+		op = match{n: int(n) + minMatchLen,
+			distance: int64(d.State.rep[0]) + minDistance}
+		return op, nil
+	}
+	b, err = d.State.isRepG0[state].Decode(d.rd)
+	if err != nil {
+		return nil, err
+	}
+	dist := d.State.rep[0]
+	if b == 0 {
+		// rep match 0
+		b, err = d.State.isRepG0Long[state2].Decode(d.rd)
+		if err != nil {
+			return nil, err
+		}
+		if b == 0 {
+			d.State.updateStateShortRep()
+			op = match{n: 1, distance: int64(dist) + minDistance}
+			return op, nil
+		}
+	} else {
+		b, err = d.State.isRepG1[state].Decode(d.rd)
+		if err != nil {
+			return nil, err
+		}
+		if b == 0 {
+			dist = d.State.rep[1]
+		} else {
+			b, err = d.State.isRepG2[state].Decode(d.rd)
+			if err != nil {
+				return nil, err
+			}
+			if b == 0 {
+				dist = d.State.rep[2]
+			} else {
+				dist = d.State.rep[3]
+				d.State.rep[3] = d.State.rep[2]
+			}
+			d.State.rep[2] = d.State.rep[1]
+		}
+		d.State.rep[1] = d.State.rep[0]
+		d.State.rep[0] = dist
+	}
+	n, err := d.State.repLenCodec.Decode(d.rd, posState)
+	if err != nil {
+		return nil, err
+	}
+	d.State.updateStateRep()
+	op = match{n: int(n) + minMatchLen, distance: int64(dist) + minDistance}
+	return op, nil
+}
+
+// apply takes the operation and transforms the decoder dictionary accordingly.
+func (d *decoder) apply(op operation) error {
+	var err error
+	switch x := op.(type) {
+	case match:
+		err = d.Dict.writeMatch(x.distance, x.n)
+	case lit:
+		err = d.Dict.WriteByte(x.b)
+	default:
+		panic("op is neither a match nor a literal")
+	}
+	return err
+}
+
+// decompress fills the dictionary unless no space for new data is
+// available. If the end of the LZMA stream has been reached io.EOF will
+// be returned.
+func (d *decoder) decompress() error {
+	if d.eos {
+		return io.EOF
+	}
+	for d.Dict.Available() >= maxMatchLen {
+		op, err := d.readOp()
+		switch err {
+		case nil:
+			break
+		case errEOS:
+			d.eos = true
+			if !d.rd.possiblyAtEnd() {
+				return errDataAfterEOS
+			}
+			if d.size >= 0 && d.size != d.Decompressed() {
+				return errSize
+			}
+			return io.EOF
+		case io.EOF:
+			d.eos = true
+			return io.ErrUnexpectedEOF
+		default:
+			return err
+		}
+		if err = d.apply(op); err != nil {
+			return err
+		}
+		if d.size >= 0 && d.Decompressed() >= d.size {
+			d.eos = true
+			if d.Decompressed() > d.size {
+				return errSize
+			}
+			if !d.rd.possiblyAtEnd() {
+				switch _, err = d.readOp(); err {
+				case nil:
+					return errSize
+				case io.EOF:
+					return io.ErrUnexpectedEOF
+				case errEOS:
+					break
+				default:
+					return err
+				}
+			}
+			return io.EOF
+		}
+	}
+	return nil
+}
+
+// Errors that may be returned while decoding data.
+var (
+	errDataAfterEOS = errors.New("lzma: data after end of stream marker")
+	errSize         = errors.New("lzma: wrong uncompressed data size")
+)
+
+// Read reads data from the buffer. If no more data is available io.EOF is
+// returned.
+func (d *decoder) Read(p []byte) (n int, err error) {
+	var k int
+	for {
+		// Read of decoder dict never returns an error.
+		k, err = d.Dict.Read(p[n:])
+		if err != nil {
+			panic(fmt.Errorf("dictionary read error %s", err))
+		}
+		if k == 0 && d.eos {
+			return n, io.EOF
+		}
+		n += k
+		if n >= len(p) {
+			return n, nil
+		}
+		if err = d.decompress(); err != nil && err != io.EOF {
+			return n, err
+		}
+	}
+}
+
+// Decompressed returns the number of bytes decompressed by the decoder.
+func (d *decoder) Decompressed() int64 {
+	return d.Dict.pos() - d.start
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/decoderdict.go b/vendor/github.com/ulikunitz/xz/lzma/decoderdict.go
new file mode 100644
index 000000000..564a12b83
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/decoderdict.go
@@ -0,0 +1,135 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"fmt"
+)
+
+// decoderDict provides the dictionary for the decoder. The whole
+// dictionary is used as reader buffer.
+type decoderDict struct {
+	buf  buffer
+	head int64
+}
+
+// newDecoderDict creates a new decoder dictionary. The whole dictionary
+// will be used as reader buffer.
+func newDecoderDict(dictCap int) (d *decoderDict, err error) {
+	// lower limit supports easy test cases
+	if !(1 <= dictCap && int64(dictCap) <= MaxDictCap) {
+		return nil, errors.New("lzma: dictCap out of range")
+	}
+	d = &decoderDict{buf: *newBuffer(dictCap)}
+	return d, nil
+}
+
+// Reset clears the dictionary. The read buffer is not changed, so the
+// buffered data can still be read.
+func (d *decoderDict) Reset() {
+	d.head = 0
+}
+
+// WriteByte writes a single byte into the dictionary. It is used to
+// write literals into the dictionary.
+func (d *decoderDict) WriteByte(c byte) error {
+	if err := d.buf.WriteByte(c); err != nil {
+		return err
+	}
+	d.head++
+	return nil
+}
+
+// pos returns the position of the dictionary head.
+func (d *decoderDict) pos() int64 { return d.head }
+
+// dictLen returns the actual length of the dictionary.
+func (d *decoderDict) dictLen() int {
+	capacity := d.buf.Cap()
+	if d.head >= int64(capacity) {
+		return capacity
+	}
+	return int(d.head)
+}
+
+// byteAt returns a byte stored in the dictionary. If the distance is
+// non-positive or exceeds the current length of the dictionary the zero
+// byte is returned.
+func (d *decoderDict) byteAt(dist int) byte {
+	if !(0 < dist && dist <= d.dictLen()) {
+		return 0
+	}
+	i := d.buf.front - dist
+	if i < 0 {
+		i += len(d.buf.data)
+	}
+	return d.buf.data[i]
+}
+
+// writeMatch writes the match at the top of the dictionary. The given
+// distance must point in the current dictionary and the length must not
+// exceed the maximum length 273 supported in LZMA.
+//
+// The error value ErrNoSpace indicates that no space is available in
+// the dictionary for writing. You need to read from the dictionary
+// first.
+func (d *decoderDict) writeMatch(dist int64, length int) error {
+	if !(0 < dist && dist <= int64(d.dictLen())) {
+		return errors.New("writeMatch: distance out of range")
+	}
+	if !(0 < length && length <= maxMatchLen) {
+		return errors.New("writeMatch: length out of range")
+	}
+	if length > d.buf.Available() {
+		return ErrNoSpace
+	}
+	d.head += int64(length)
+
+	i := d.buf.front - int(dist)
+	if i < 0 {
+		i += len(d.buf.data)
+	}
+	for length > 0 {
+		var p []byte
+		if i >= d.buf.front {
+			p = d.buf.data[i:]
+			i = 0
+		} else {
+			p = d.buf.data[i:d.buf.front]
+			i = d.buf.front
+		}
+		if len(p) > length {
+			p = p[:length]
+		}
+		if _, err := d.buf.Write(p); err != nil {
+			panic(fmt.Errorf("d.buf.Write returned error %s", err))
+		}
+		length -= len(p)
+	}
+	return nil
+}
+
+// Write writes the given bytes into the dictionary and advances the
+// head.
+func (d *decoderDict) Write(p []byte) (n int, err error) {
+	n, err = d.buf.Write(p)
+	d.head += int64(n)
+	return n, err
+}
+
+// Available returns the number of available bytes for writing into the
+// decoder dictionary.
+func (d *decoderDict) Available() int { return d.buf.Available() }
+
+// Read reads data from the buffer contained in the decoder dictionary.
+func (d *decoderDict) Read(p []byte) (n int, err error) { return d.buf.Read(p) }
+
+// Buffered returns the number of bytes currently buffered in the
+// decoder dictionary.
+func (d *decoderDict) buffered() int { return d.buf.Buffered() }
+
+// Peek gets data from the buffer without advancing the rear index.
+func (d *decoderDict) peek(p []byte) (n int, err error) { return d.buf.Peek(p) }
diff --git a/vendor/github.com/ulikunitz/xz/lzma/directcodec.go b/vendor/github.com/ulikunitz/xz/lzma/directcodec.go
new file mode 100644
index 000000000..e08eb989f
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/directcodec.go
@@ -0,0 +1,49 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import "fmt"
+
+// directCodec allows the encoding and decoding of values with a fixed number
+// of bits. The number of bits must be in the range [1,32].
+type directCodec byte
+
+// makeDirectCodec creates a directCodec. The function panics if the number of
+// bits is not in the range [1,32].
+func makeDirectCodec(bits int) directCodec {
+	if !(1 <= bits && bits <= 32) {
+		panic(fmt.Errorf("bits=%d out of range", bits))
+	}
+	return directCodec(bits)
+}
+
+// Bits returns the number of bits supported by this codec.
+func (dc directCodec) Bits() int {
+	return int(dc)
+}
+
+// Encode uses the range encoder to encode a value with the fixed number of
+// bits. The most-significant bit is encoded first.
+func (dc directCodec) Encode(e *rangeEncoder, v uint32) error {
+	for i := int(dc) - 1; i >= 0; i-- {
+		if err := e.DirectEncodeBit(v >> uint(i)); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Decode uses the range decoder to decode a value with the given number of
+// given bits. The most-significant bit is decoded first.
+func (dc directCodec) Decode(d *rangeDecoder) (v uint32, err error) {
+	for i := int(dc) - 1; i >= 0; i-- {
+		x, err := d.DirectDecodeBit()
+		if err != nil {
+			return 0, err
+		}
+		v = (v << 1) | x
+	}
+	return v, nil
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/distcodec.go b/vendor/github.com/ulikunitz/xz/lzma/distcodec.go
new file mode 100644
index 000000000..b053a2dce
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/distcodec.go
@@ -0,0 +1,156 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+// Constants used by the distance codec.
+const (
+	// minimum supported distance
+	minDistance = 1
+	// maximum supported distance, value is used for the eos marker.
+	maxDistance = 1 << 32
+	// number of the supported len states
+	lenStates = 4
+	// start for the position models
+	startPosModel = 4
+	// first index with align bits support
+	endPosModel = 14
+	// bits for the position slots
+	posSlotBits = 6
+	// number of align bits
+	alignBits = 4
+	// maximum position slot
+	maxPosSlot = 63
+)
+
+// distCodec provides encoding and decoding of distance values.
+type distCodec struct {
+	posSlotCodecs [lenStates]treeCodec
+	posModel      [endPosModel - startPosModel]treeReverseCodec
+	alignCodec    treeReverseCodec
+}
+
+// deepcopy initializes dc as deep copy of the source.
+func (dc *distCodec) deepcopy(src *distCodec) {
+	if dc == src {
+		return
+	}
+	for i := range dc.posSlotCodecs {
+		dc.posSlotCodecs[i].deepcopy(&src.posSlotCodecs[i])
+	}
+	for i := range dc.posModel {
+		dc.posModel[i].deepcopy(&src.posModel[i])
+	}
+	dc.alignCodec.deepcopy(&src.alignCodec)
+}
+
+// distBits returns the number of bits required to encode dist.
+func distBits(dist uint32) int {
+	if dist < startPosModel {
+		return 6
+	}
+	// slot s > 3, dist d
+	// s = 2(bits(d)-1) + bit(d, bits(d)-2)
+	// s>>1 = bits(d)-1
+	// bits(d) = 32-nlz32(d)
+	// s>>1=31-nlz32(d)
+	// n = 5 + (s>>1) = 36 - nlz32(d)
+	return 36 - nlz32(dist)
+}
+
+// newDistCodec creates a new distance codec.
+func (dc *distCodec) init() {
+	for i := range dc.posSlotCodecs {
+		dc.posSlotCodecs[i] = makeTreeCodec(posSlotBits)
+	}
+	for i := range dc.posModel {
+		posSlot := startPosModel + i
+		bits := (posSlot >> 1) - 1
+		dc.posModel[i] = makeTreeReverseCodec(bits)
+	}
+	dc.alignCodec = makeTreeReverseCodec(alignBits)
+}
+
+// lenState converts the value l to a supported lenState value.
+func lenState(l uint32) uint32 {
+	if l >= lenStates {
+		l = lenStates - 1
+	}
+	return l
+}
+
+// Encode encodes the distance using the parameter l. Dist can have values from
+// the full range of uint32 values. To get the distance offset the actual match
+// distance has to be decreased by 1. A distance offset of 0xffffffff (eos)
+// indicates the end of the stream.
+func (dc *distCodec) Encode(e *rangeEncoder, dist uint32, l uint32) (err error) {
+	// Compute the posSlot using nlz32
+	var posSlot uint32
+	var bits uint32
+	if dist < startPosModel {
+		posSlot = dist
+	} else {
+		bits = uint32(30 - nlz32(dist))
+		posSlot = startPosModel - 2 + (bits << 1)
+		posSlot += (dist >> uint(bits)) & 1
+	}
+
+	if err = dc.posSlotCodecs[lenState(l)].Encode(e, posSlot); err != nil {
+		return
+	}
+
+	switch {
+	case posSlot < startPosModel:
+		return nil
+	case posSlot < endPosModel:
+		tc := &dc.posModel[posSlot-startPosModel]
+		return tc.Encode(dist, e)
+	}
+	dic := directCodec(bits - alignBits)
+	if err = dic.Encode(e, dist>>alignBits); err != nil {
+		return
+	}
+	return dc.alignCodec.Encode(dist, e)
+}
+
+// Decode decodes the distance offset using the parameter l. The dist value
+// 0xffffffff (eos) indicates the end of the stream. Add one to the distance
+// offset to get the actual match distance.
+func (dc *distCodec) Decode(d *rangeDecoder, l uint32) (dist uint32, err error) {
+	posSlot, err := dc.posSlotCodecs[lenState(l)].Decode(d)
+	if err != nil {
+		return
+	}
+
+	// posSlot equals distance
+	if posSlot < startPosModel {
+		return posSlot, nil
+	}
+
+	// posSlot uses the individual models
+	bits := (posSlot >> 1) - 1
+	dist = (2 | (posSlot & 1)) << bits
+	var u uint32
+	if posSlot < endPosModel {
+		tc := &dc.posModel[posSlot-startPosModel]
+		if u, err = tc.Decode(d); err != nil {
+			return 0, err
+		}
+		dist += u
+		return dist, nil
+	}
+
+	// posSlots use direct encoding and a single model for the four align
+	// bits.
+	dic := directCodec(bits - alignBits)
+	if u, err = dic.Decode(d); err != nil {
+		return 0, err
+	}
+	dist += u << alignBits
+	if u, err = dc.alignCodec.Decode(d); err != nil {
+		return 0, err
+	}
+	dist += u
+	return dist, nil
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/encoder.go b/vendor/github.com/ulikunitz/xz/lzma/encoder.go
new file mode 100644
index 000000000..18ce00992
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/encoder.go
@@ -0,0 +1,268 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"fmt"
+	"io"
+)
+
+// opLenMargin provides the upper limit of the number of bytes required
+// to encode a single operation.
+const opLenMargin = 10
+
+// compressFlags control the compression process.
+type compressFlags uint32
+
+// Values for compressFlags.
+const (
+	// all data should be compressed, even if compression is not
+	// optimal.
+	all compressFlags = 1 << iota
+)
+
+// encoderFlags provide the flags for an encoder.
+type encoderFlags uint32
+
+// Flags for the encoder.
+const (
+	// eosMarker requests an EOS marker to be written.
+	eosMarker encoderFlags = 1 << iota
+)
+
+// Encoder compresses data buffered in the encoder dictionary and writes
+// it into a byte writer.
+type encoder struct {
+	dict  *encoderDict
+	state *state
+	re    *rangeEncoder
+	start int64
+	// generate eos marker
+	marker bool
+	limit  bool
+	margin int
+}
+
+// newEncoder creates a new encoder. If the byte writer must be
+// limited use LimitedByteWriter provided by this package. The flags
+// argument supports the eosMarker flag, controlling whether a
+// terminating end-of-stream marker must be written.
+func newEncoder(bw io.ByteWriter, state *state, dict *encoderDict,
+	flags encoderFlags) (e *encoder, err error) {
+
+	re, err := newRangeEncoder(bw)
+	if err != nil {
+		return nil, err
+	}
+	e = &encoder{
+		dict:   dict,
+		state:  state,
+		re:     re,
+		marker: flags&eosMarker != 0,
+		start:  dict.Pos(),
+		margin: opLenMargin,
+	}
+	if e.marker {
+		e.margin += 5
+	}
+	return e, nil
+}
+
+// Write writes the bytes from p into the dictionary. If not enough
+// space is available the data in the dictionary buffer will be
+// compressed to make additional space available. If the limit of the
+// underlying writer has been reached ErrLimit will be returned.
+func (e *encoder) Write(p []byte) (n int, err error) {
+	for {
+		k, err := e.dict.Write(p[n:])
+		n += k
+		if err == ErrNoSpace {
+			if err = e.compress(0); err != nil {
+				return n, err
+			}
+			continue
+		}
+		return n, err
+	}
+}
+
+// Reopen reopens the encoder with a new byte writer.
+func (e *encoder) Reopen(bw io.ByteWriter) error {
+	var err error
+	if e.re, err = newRangeEncoder(bw); err != nil {
+		return err
+	}
+	e.start = e.dict.Pos()
+	e.limit = false
+	return nil
+}
+
+// writeLiteral writes a literal into the LZMA stream
+func (e *encoder) writeLiteral(l lit) error {
+	var err error
+	state, state2, _ := e.state.states(e.dict.Pos())
+	if err = e.state.isMatch[state2].Encode(e.re, 0); err != nil {
+		return err
+	}
+	litState := e.state.litState(e.dict.ByteAt(1), e.dict.Pos())
+	match := e.dict.ByteAt(int(e.state.rep[0]) + 1)
+	err = e.state.litCodec.Encode(e.re, l.b, state, match, litState)
+	if err != nil {
+		return err
+	}
+	e.state.updateStateLiteral()
+	return nil
+}
+
+// iverson implements the Iverson operator as proposed by Donald Knuth in his
+// book Concrete Mathematics.
+func iverson(ok bool) uint32 {
+	if ok {
+		return 1
+	}
+	return 0
+}
+
+// writeMatch writes a repetition operation into the operation stream
+func (e *encoder) writeMatch(m match) error {
+	var err error
+	if !(minDistance <= m.distance && m.distance <= maxDistance) {
+		panic(fmt.Errorf("match distance %d out of range", m.distance))
+	}
+	dist := uint32(m.distance - minDistance)
+	if !(minMatchLen <= m.n && m.n <= maxMatchLen) &&
+		!(dist == e.state.rep[0] && m.n == 1) {
+		panic(fmt.Errorf(
+			"match length %d out of range; dist %d rep[0] %d",
+			m.n, dist, e.state.rep[0]))
+	}
+	state, state2, posState := e.state.states(e.dict.Pos())
+	if err = e.state.isMatch[state2].Encode(e.re, 1); err != nil {
+		return err
+	}
+	g := 0
+	for ; g < 4; g++ {
+		if e.state.rep[g] == dist {
+			break
+		}
+	}
+	b := iverson(g < 4)
+	if err = e.state.isRep[state].Encode(e.re, b); err != nil {
+		return err
+	}
+	n := uint32(m.n - minMatchLen)
+	if b == 0 {
+		// simple match
+		e.state.rep[3], e.state.rep[2], e.state.rep[1], e.state.rep[0] =
+			e.state.rep[2], e.state.rep[1], e.state.rep[0], dist
+		e.state.updateStateMatch()
+		if err = e.state.lenCodec.Encode(e.re, n, posState); err != nil {
+			return err
+		}
+		return e.state.distCodec.Encode(e.re, dist, n)
+	}
+	b = iverson(g != 0)
+	if err = e.state.isRepG0[state].Encode(e.re, b); err != nil {
+		return err
+	}
+	if b == 0 {
+		// g == 0
+		b = iverson(m.n != 1)
+		if err = e.state.isRepG0Long[state2].Encode(e.re, b); err != nil {
+			return err
+		}
+		if b == 0 {
+			e.state.updateStateShortRep()
+			return nil
+		}
+	} else {
+		// g in {1,2,3}
+		b = iverson(g != 1)
+		if err = e.state.isRepG1[state].Encode(e.re, b); err != nil {
+			return err
+		}
+		if b == 1 {
+			// g in {2,3}
+			b = iverson(g != 2)
+			err = e.state.isRepG2[state].Encode(e.re, b)
+			if err != nil {
+				return err
+			}
+			if b == 1 {
+				e.state.rep[3] = e.state.rep[2]
+			}
+			e.state.rep[2] = e.state.rep[1]
+		}
+		e.state.rep[1] = e.state.rep[0]
+		e.state.rep[0] = dist
+	}
+	e.state.updateStateRep()
+	return e.state.repLenCodec.Encode(e.re, n, posState)
+}
+
+// writeOp writes a single operation to the range encoder. The function
+// checks whether there is enough space available to close the LZMA
+// stream.
+func (e *encoder) writeOp(op operation) error {
+	if e.re.Available() < int64(e.margin) {
+		return ErrLimit
+	}
+	switch x := op.(type) {
+	case lit:
+		return e.writeLiteral(x)
+	case match:
+		return e.writeMatch(x)
+	default:
+		panic("unexpected operation")
+	}
+}
+
+// compress compressed data from the dictionary buffer. If the flag all
+// is set, all data in the dictionary buffer will be compressed. The
+// function returns ErrLimit if the underlying writer has reached its
+// limit.
+func (e *encoder) compress(flags compressFlags) error {
+	n := 0
+	if flags&all == 0 {
+		n = maxMatchLen - 1
+	}
+	d := e.dict
+	m := d.m
+	for d.Buffered() > n {
+		op := m.NextOp(e.state.rep)
+		if err := e.writeOp(op); err != nil {
+			return err
+		}
+		d.Discard(op.Len())
+	}
+	return nil
+}
+
+// eosMatch is a pseudo operation that indicates the end of the stream.
+var eosMatch = match{distance: maxDistance, n: minMatchLen}
+
+// Close terminates the LZMA stream. If requested the end-of-stream
+// marker will be written. If the byte writer limit has been or will be
+// reached during compression of the remaining data in the buffer the
+// LZMA stream will be closed and data will remain in the buffer.
+func (e *encoder) Close() error {
+	err := e.compress(all)
+	if err != nil && err != ErrLimit {
+		return err
+	}
+	if e.marker {
+		if err := e.writeMatch(eosMatch); err != nil {
+			return err
+		}
+	}
+	err = e.re.Close()
+	return err
+}
+
+// Compressed returns the number bytes of the input data that been
+// compressed.
+func (e *encoder) Compressed() int64 {
+	return e.dict.Pos() - e.start
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/encoderdict.go b/vendor/github.com/ulikunitz/xz/lzma/encoderdict.go
new file mode 100644
index 000000000..9d0fbc703
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/encoderdict.go
@@ -0,0 +1,149 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"fmt"
+	"io"
+)
+
+// matcher is an interface that supports the identification of the next
+// operation.
+type matcher interface {
+	io.Writer
+	SetDict(d *encoderDict)
+	NextOp(rep [4]uint32) operation
+}
+
+// encoderDict provides the dictionary of the encoder. It includes an
+// addtional buffer atop of the actual dictionary.
+type encoderDict struct {
+	buf      buffer
+	m        matcher
+	head     int64
+	capacity int
+	// preallocated array
+	data [maxMatchLen]byte
+}
+
+// newEncoderDict creates the encoder dictionary. The argument bufSize
+// defines the size of the additional buffer.
+func newEncoderDict(dictCap, bufSize int, m matcher) (d *encoderDict, err error) {
+	if !(1 <= dictCap && int64(dictCap) <= MaxDictCap) {
+		return nil, errors.New(
+			"lzma: dictionary capacity out of range")
+	}
+	if bufSize < 1 {
+		return nil, errors.New(
+			"lzma: buffer size must be larger than zero")
+	}
+	d = &encoderDict{
+		buf:      *newBuffer(dictCap + bufSize),
+		capacity: dictCap,
+		m:        m,
+	}
+	m.SetDict(d)
+	return d, nil
+}
+
+// Discard discards n bytes. Note that n must not be larger than
+// MaxMatchLen.
+func (d *encoderDict) Discard(n int) {
+	p := d.data[:n]
+	k, _ := d.buf.Read(p)
+	if k < n {
+		panic(fmt.Errorf("lzma: can't discard %d bytes", n))
+	}
+	d.head += int64(n)
+	d.m.Write(p)
+}
+
+// Len returns the data available in the encoder dictionary.
+func (d *encoderDict) Len() int {
+	n := d.buf.Available()
+	if int64(n) > d.head {
+		return int(d.head)
+	}
+	return n
+}
+
+// DictLen returns the actual length of data in the dictionary.
+func (d *encoderDict) DictLen() int {
+	if d.head < int64(d.capacity) {
+		return int(d.head)
+	}
+	return d.capacity
+}
+
+// Available returns the number of bytes that can be written by a
+// following Write call.
+func (d *encoderDict) Available() int {
+	return d.buf.Available() - d.DictLen()
+}
+
+// Write writes data into the dictionary buffer. Note that the position
+// of the dictionary head will not be moved. If there is not enough
+// space in the buffer ErrNoSpace will be returned.
+func (d *encoderDict) Write(p []byte) (n int, err error) {
+	m := d.Available()
+	if len(p) > m {
+		p = p[:m]
+		err = ErrNoSpace
+	}
+	var e error
+	if n, e = d.buf.Write(p); e != nil {
+		err = e
+	}
+	return n, err
+}
+
+// Pos returns the position of the head.
+func (d *encoderDict) Pos() int64 { return d.head }
+
+// ByteAt returns the byte at the given distance.
+func (d *encoderDict) ByteAt(distance int) byte {
+	if !(0 < distance && distance <= d.Len()) {
+		return 0
+	}
+	i := d.buf.rear - distance
+	if i < 0 {
+		i += len(d.buf.data)
+	}
+	return d.buf.data[i]
+}
+
+// CopyN copies the last n bytes from the dictionary into the provided
+// writer. This is used for copying uncompressed data into an
+// uncompressed segment.
+func (d *encoderDict) CopyN(w io.Writer, n int) (written int, err error) {
+	if n <= 0 {
+		return 0, nil
+	}
+	m := d.Len()
+	if n > m {
+		n = m
+		err = ErrNoSpace
+	}
+	i := d.buf.rear - n
+	var e error
+	if i < 0 {
+		i += len(d.buf.data)
+		if written, e = w.Write(d.buf.data[i:]); e != nil {
+			return written, e
+		}
+		i = 0
+	}
+	var k int
+	k, e = w.Write(d.buf.data[i:d.buf.rear])
+	written += k
+	if e != nil {
+		err = e
+	}
+	return written, err
+}
+
+// Buffered returns the number of bytes in the buffer.
+func (d *encoderDict) Buffered() int { return d.buf.Buffered() }
diff --git a/vendor/github.com/ulikunitz/xz/lzma/hashtable.go b/vendor/github.com/ulikunitz/xz/lzma/hashtable.go
new file mode 100644
index 000000000..d786a9745
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/hashtable.go
@@ -0,0 +1,309 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/ulikunitz/xz/internal/hash"
+)
+
+/* For compression we need to find byte sequences that match the byte
+ * sequence at the dictionary head. A hash table is a simple method to
+ * provide this capability.
+ */
+
+// maxMatches limits the number of matches requested from the Matches
+// function. This controls the speed of the overall encoding.
+const maxMatches = 16
+
+// shortDists defines the number of short distances supported by the
+// implementation.
+const shortDists = 8
+
+// The minimum is somehow arbitrary but the maximum is limited by the
+// memory requirements of the hash table.
+const (
+	minTableExponent = 9
+	maxTableExponent = 20
+)
+
+// newRoller contains the function used to create an instance of the
+// hash.Roller.
+var newRoller = func(n int) hash.Roller { return hash.NewCyclicPoly(n) }
+
+// hashTable stores the hash table including the rolling hash method.
+//
+// We implement chained hashing into a circular buffer. Each entry in
+// the circular buffer stores the delta distance to the next position with a
+// word that has the same hash value.
+type hashTable struct {
+	dict *encoderDict
+	// actual hash table
+	t []int64
+	// circular list data with the offset to the next word
+	data  []uint32
+	front int
+	// mask for computing the index for the hash table
+	mask uint64
+	// hash offset; initial value is -int64(wordLen)
+	hoff int64
+	// length of the hashed word
+	wordLen int
+	// hash roller for computing the hash values for the Write
+	// method
+	wr hash.Roller
+	// hash roller for computing arbitrary hashes
+	hr hash.Roller
+	// preallocated slices
+	p         [maxMatches]int64
+	distances [maxMatches + shortDists]int
+}
+
+// hashTableExponent derives the hash table exponent from the dictionary
+// capacity.
+func hashTableExponent(n uint32) int {
+	e := 30 - nlz32(n)
+	switch {
+	case e < minTableExponent:
+		e = minTableExponent
+	case e > maxTableExponent:
+		e = maxTableExponent
+	}
+	return e
+}
+
+// newHashTable creates a new hash table for words of length wordLen
+func newHashTable(capacity int, wordLen int) (t *hashTable, err error) {
+	if !(0 < capacity) {
+		return nil, errors.New(
+			"newHashTable: capacity must not be negative")
+	}
+	exp := hashTableExponent(uint32(capacity))
+	if !(1 <= wordLen && wordLen <= 4) {
+		return nil, errors.New("newHashTable: " +
+			"argument wordLen out of range")
+	}
+	n := 1 << uint(exp)
+	if n <= 0 {
+		panic("newHashTable: exponent is too large")
+	}
+	t = &hashTable{
+		t:       make([]int64, n),
+		data:    make([]uint32, capacity),
+		mask:    (uint64(1) << uint(exp)) - 1,
+		hoff:    -int64(wordLen),
+		wordLen: wordLen,
+		wr:      newRoller(wordLen),
+		hr:      newRoller(wordLen),
+	}
+	return t, nil
+}
+
+func (t *hashTable) SetDict(d *encoderDict) { t.dict = d }
+
+// buffered returns the number of bytes that are currently hashed.
+func (t *hashTable) buffered() int {
+	n := t.hoff + 1
+	switch {
+	case n <= 0:
+		return 0
+	case n >= int64(len(t.data)):
+		return len(t.data)
+	}
+	return int(n)
+}
+
+// addIndex adds n to an index ensuring that is stays inside the
+// circular buffer for the hash chain.
+func (t *hashTable) addIndex(i, n int) int {
+	i += n - len(t.data)
+	if i < 0 {
+		i += len(t.data)
+	}
+	return i
+}
+
+// putDelta puts the delta instance at the current front of the circular
+// chain buffer.
+func (t *hashTable) putDelta(delta uint32) {
+	t.data[t.front] = delta
+	t.front = t.addIndex(t.front, 1)
+}
+
+// putEntry puts a new entry into the hash table. If there is already a
+// value stored it is moved into the circular chain buffer.
+func (t *hashTable) putEntry(h uint64, pos int64) {
+	if pos < 0 {
+		return
+	}
+	i := h & t.mask
+	old := t.t[i] - 1
+	t.t[i] = pos + 1
+	var delta int64
+	if old >= 0 {
+		delta = pos - old
+		if delta > 1<<32-1 || delta > int64(t.buffered()) {
+			delta = 0
+		}
+	}
+	t.putDelta(uint32(delta))
+}
+
+// WriteByte converts a single byte into a hash and puts them into the hash
+// table.
+func (t *hashTable) WriteByte(b byte) error {
+	h := t.wr.RollByte(b)
+	t.hoff++
+	t.putEntry(h, t.hoff)
+	return nil
+}
+
+// Write converts the bytes provided into hash tables and stores the
+// abbreviated offsets into the hash table. The method will never return an
+// error.
+func (t *hashTable) Write(p []byte) (n int, err error) {
+	for _, b := range p {
+		// WriteByte doesn't generate an error.
+		t.WriteByte(b)
+	}
+	return len(p), nil
+}
+
+// getMatches the matches for a specific hash. The functions returns the
+// number of positions found.
+//
+// TODO: Make a getDistances because that we are actually interested in.
+func (t *hashTable) getMatches(h uint64, positions []int64) (n int) {
+	if t.hoff < 0 || len(positions) == 0 {
+		return 0
+	}
+	buffered := t.buffered()
+	tailPos := t.hoff + 1 - int64(buffered)
+	rear := t.front - buffered
+	if rear >= 0 {
+		rear -= len(t.data)
+	}
+	// get the slot for the hash
+	pos := t.t[h&t.mask] - 1
+	delta := pos - tailPos
+	for {
+		if delta < 0 {
+			return n
+		}
+		positions[n] = tailPos + delta
+		n++
+		if n >= len(positions) {
+			return n
+		}
+		i := rear + int(delta)
+		if i < 0 {
+			i += len(t.data)
+		}
+		u := t.data[i]
+		if u == 0 {
+			return n
+		}
+		delta -= int64(u)
+	}
+}
+
+// hash computes the rolling hash for the word stored in p. For correct
+// results its length must be equal to t.wordLen.
+func (t *hashTable) hash(p []byte) uint64 {
+	var h uint64
+	for _, b := range p {
+		h = t.hr.RollByte(b)
+	}
+	return h
+}
+
+// Matches fills the positions slice with potential matches. The
+// functions returns the number of positions filled into positions. The
+// byte slice p must have word length of the hash table.
+func (t *hashTable) Matches(p []byte, positions []int64) int {
+	if len(p) != t.wordLen {
+		panic(fmt.Errorf(
+			"byte slice must have length %d", t.wordLen))
+	}
+	h := t.hash(p)
+	return t.getMatches(h, positions)
+}
+
+// NextOp identifies the next operation using the hash table.
+//
+// TODO: Use all repetitions to find matches.
+func (t *hashTable) NextOp(rep [4]uint32) operation {
+	// get positions
+	data := t.dict.data[:maxMatchLen]
+	n, _ := t.dict.buf.Peek(data)
+	data = data[:n]
+	var p []int64
+	if n < t.wordLen {
+		p = t.p[:0]
+	} else {
+		p = t.p[:maxMatches]
+		n = t.Matches(data[:t.wordLen], p)
+		p = p[:n]
+	}
+
+	// convert positions in potential distances
+	head := t.dict.head
+	dists := append(t.distances[:0], 1, 2, 3, 4, 5, 6, 7, 8)
+	for _, pos := range p {
+		dis := int(head - pos)
+		if dis > shortDists {
+			dists = append(dists, dis)
+		}
+	}
+
+	// check distances
+	var m match
+	dictLen := t.dict.DictLen()
+	for _, dist := range dists {
+		if dist > dictLen {
+			continue
+		}
+
+		// Here comes a trick. We are only interested in matches
+		// that are longer than the matches we have been found
+		// before. So before we test the whole byte sequence at
+		// the given distance, we test the first byte that would
+		// make the match longer. If it doesn't match the byte
+		// to match, we don't to care any longer.
+		i := t.dict.buf.rear - dist + m.n
+		if i < 0 {
+			i += len(t.dict.buf.data)
+		}
+		if t.dict.buf.data[i] != data[m.n] {
+			// We can't get a longer match. Jump to the next
+			// distance.
+			continue
+		}
+
+		n := t.dict.buf.matchLen(dist, data)
+		switch n {
+		case 0:
+			continue
+		case 1:
+			if uint32(dist-minDistance) != rep[0] {
+				continue
+			}
+		}
+		if n > m.n {
+			m = match{int64(dist), n}
+			if n == len(data) {
+				// No better match will be found.
+				break
+			}
+		}
+	}
+
+	if m.n == 0 {
+		return lit{data[0]}
+	}
+	return m
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/header.go b/vendor/github.com/ulikunitz/xz/lzma/header.go
new file mode 100644
index 000000000..bc708969f
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/header.go
@@ -0,0 +1,167 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"fmt"
+)
+
+// uint32LE reads an uint32 integer from a byte slice
+func uint32LE(b []byte) uint32 {
+	x := uint32(b[3]) << 24
+	x |= uint32(b[2]) << 16
+	x |= uint32(b[1]) << 8
+	x |= uint32(b[0])
+	return x
+}
+
+// uint64LE converts the uint64 value stored as little endian to an uint64
+// value.
+func uint64LE(b []byte) uint64 {
+	x := uint64(b[7]) << 56
+	x |= uint64(b[6]) << 48
+	x |= uint64(b[5]) << 40
+	x |= uint64(b[4]) << 32
+	x |= uint64(b[3]) << 24
+	x |= uint64(b[2]) << 16
+	x |= uint64(b[1]) << 8
+	x |= uint64(b[0])
+	return x
+}
+
+// putUint32LE puts an uint32 integer into a byte slice that must have at least
+// a length of 4 bytes.
+func putUint32LE(b []byte, x uint32) {
+	b[0] = byte(x)
+	b[1] = byte(x >> 8)
+	b[2] = byte(x >> 16)
+	b[3] = byte(x >> 24)
+}
+
+// putUint64LE puts the uint64 value into the byte slice as little endian
+// value. The byte slice b must have at least place for 8 bytes.
+func putUint64LE(b []byte, x uint64) {
+	b[0] = byte(x)
+	b[1] = byte(x >> 8)
+	b[2] = byte(x >> 16)
+	b[3] = byte(x >> 24)
+	b[4] = byte(x >> 32)
+	b[5] = byte(x >> 40)
+	b[6] = byte(x >> 48)
+	b[7] = byte(x >> 56)
+}
+
+// noHeaderSize defines the value of the length field in the LZMA header.
+const noHeaderSize uint64 = 1<<64 - 1
+
+// HeaderLen provides the length of the LZMA file header.
+const HeaderLen = 13
+
+// header represents the header of an LZMA file.
+type header struct {
+	properties Properties
+	dictCap    int
+	// uncompressed size; negative value if no size is given
+	size int64
+}
+
+// marshalBinary marshals the header.
+func (h *header) marshalBinary() (data []byte, err error) {
+	if err = h.properties.verify(); err != nil {
+		return nil, err
+	}
+	if !(0 <= h.dictCap && int64(h.dictCap) <= MaxDictCap) {
+		return nil, fmt.Errorf("lzma: DictCap %d out of range",
+			h.dictCap)
+	}
+
+	data = make([]byte, 13)
+
+	// property byte
+	data[0] = h.properties.Code()
+
+	// dictionary capacity
+	putUint32LE(data[1:5], uint32(h.dictCap))
+
+	// uncompressed size
+	var s uint64
+	if h.size > 0 {
+		s = uint64(h.size)
+	} else {
+		s = noHeaderSize
+	}
+	putUint64LE(data[5:], s)
+
+	return data, nil
+}
+
+// unmarshalBinary unmarshals the header.
+func (h *header) unmarshalBinary(data []byte) error {
+	if len(data) != HeaderLen {
+		return errors.New("lzma.unmarshalBinary: data has wrong length")
+	}
+
+	// properties
+	var err error
+	if h.properties, err = PropertiesForCode(data[0]); err != nil {
+		return err
+	}
+
+	// dictionary capacity
+	h.dictCap = int(uint32LE(data[1:]))
+	if h.dictCap < 0 {
+		return errors.New(
+			"LZMA header: dictionary capacity exceeds maximum " +
+				"integer")
+	}
+
+	// uncompressed size
+	s := uint64LE(data[5:])
+	if s == noHeaderSize {
+		h.size = -1
+	} else {
+		h.size = int64(s)
+		if h.size < 0 {
+			return errors.New(
+				"LZMA header: uncompressed size " +
+					"out of int64 range")
+		}
+	}
+
+	return nil
+}
+
+// validDictCap checks whether the dictionary capacity is correct. This
+// is used to weed out wrong file headers.
+func validDictCap(dictcap int) bool {
+	if int64(dictcap) == MaxDictCap {
+		return true
+	}
+	for n := uint(10); n < 32; n++ {
+		if dictcap == 1<<n {
+			return true
+		}
+		if dictcap == 1<<n+1<<(n-1) {
+			return true
+		}
+	}
+	return false
+}
+
+// ValidHeader checks for a valid LZMA file header. It allows only
+// dictionary sizes of 2^n or 2^n+2^(n-1) with n >= 10 or 2^32-1. If
+// there is an explicit size it must not exceed 256 GiB. The length of
+// the data argument must be HeaderLen.
+func ValidHeader(data []byte) bool {
+	var h header
+	if err := h.unmarshalBinary(data); err != nil {
+		return false
+	}
+	if !validDictCap(h.dictCap) {
+		return false
+	}
+	return h.size < 0 || h.size <= 1<<38
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/header2.go b/vendor/github.com/ulikunitz/xz/lzma/header2.go
new file mode 100644
index 000000000..ac6a71a5a
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/header2.go
@@ -0,0 +1,398 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"fmt"
+	"io"
+)
+
+const (
+	// maximum size of compressed data in a chunk
+	maxCompressed = 1 << 16
+	// maximum size of uncompressed data in a chunk
+	maxUncompressed = 1 << 21
+)
+
+// chunkType represents the type of an LZMA2 chunk. Note that this
+// value is an internal representation and no actual encoding of a LZMA2
+// chunk header.
+type chunkType byte
+
+// Possible values for the chunk type.
+const (
+	// end of stream
+	cEOS chunkType = iota
+	// uncompressed; reset dictionary
+	cUD
+	// uncompressed; no reset of dictionary
+	cU
+	// LZMA compressed; no reset
+	cL
+	// LZMA compressed; reset state
+	cLR
+	// LZMA compressed; reset state; new property value
+	cLRN
+	// LZMA compressed; reset state; new property value; reset dictionary
+	cLRND
+)
+
+// chunkTypeStrings provide a string representation for the chunk types.
+var chunkTypeStrings = [...]string{
+	cEOS:  "EOS",
+	cU:    "U",
+	cUD:   "UD",
+	cL:    "L",
+	cLR:   "LR",
+	cLRN:  "LRN",
+	cLRND: "LRND",
+}
+
+// String returns a string representation of the chunk type.
+func (c chunkType) String() string {
+	if !(cEOS <= c && c <= cLRND) {
+		return "unknown"
+	}
+	return chunkTypeStrings[c]
+}
+
+// Actual encodings for the chunk types in the value. Note that the high
+// uncompressed size bits are stored in the header byte additionally.
+const (
+	hEOS  = 0
+	hUD   = 1
+	hU    = 2
+	hL    = 1 << 7
+	hLR   = 1<<7 | 1<<5
+	hLRN  = 1<<7 | 1<<6
+	hLRND = 1<<7 | 1<<6 | 1<<5
+)
+
+// errHeaderByte indicates an unsupported value for the chunk header
+// byte. These bytes starts the variable-length chunk header.
+var errHeaderByte = errors.New("lzma: unsupported chunk header byte")
+
+// headerChunkType converts the header byte into a chunk type. It
+// ignores the uncompressed size bits in the chunk header byte.
+func headerChunkType(h byte) (c chunkType, err error) {
+	if h&hL == 0 {
+		// no compression
+		switch h {
+		case hEOS:
+			c = cEOS
+		case hUD:
+			c = cUD
+		case hU:
+			c = cU
+		default:
+			return 0, errHeaderByte
+		}
+		return
+	}
+	switch h & hLRND {
+	case hL:
+		c = cL
+	case hLR:
+		c = cLR
+	case hLRN:
+		c = cLRN
+	case hLRND:
+		c = cLRND
+	default:
+		return 0, errHeaderByte
+	}
+	return
+}
+
+// uncompressedHeaderLen provides the length of an uncompressed header
+const uncompressedHeaderLen = 3
+
+// headerLen returns the length of the LZMA2 header for a given chunk
+// type.
+func headerLen(c chunkType) int {
+	switch c {
+	case cEOS:
+		return 1
+	case cU, cUD:
+		return uncompressedHeaderLen
+	case cL, cLR:
+		return 5
+	case cLRN, cLRND:
+		return 6
+	}
+	panic(fmt.Errorf("unsupported chunk type %d", c))
+}
+
+// chunkHeader represents the contents of a chunk header.
+type chunkHeader struct {
+	ctype        chunkType
+	uncompressed uint32
+	compressed   uint16
+	props        Properties
+}
+
+// String returns a string representation of the chunk header.
+func (h *chunkHeader) String() string {
+	return fmt.Sprintf("%s %d %d %s", h.ctype, h.uncompressed,
+		h.compressed, &h.props)
+}
+
+// UnmarshalBinary reads the content of the chunk header from the data
+// slice. The slice must have the correct length.
+func (h *chunkHeader) UnmarshalBinary(data []byte) error {
+	if len(data) == 0 {
+		return errors.New("no data")
+	}
+	c, err := headerChunkType(data[0])
+	if err != nil {
+		return err
+	}
+
+	n := headerLen(c)
+	if len(data) < n {
+		return errors.New("incomplete data")
+	}
+	if len(data) > n {
+		return errors.New("invalid data length")
+	}
+
+	*h = chunkHeader{ctype: c}
+	if c == cEOS {
+		return nil
+	}
+
+	h.uncompressed = uint32(uint16BE(data[1:3]))
+	if c <= cU {
+		return nil
+	}
+	h.uncompressed |= uint32(data[0]&^hLRND) << 16
+
+	h.compressed = uint16BE(data[3:5])
+	if c <= cLR {
+		return nil
+	}
+
+	h.props, err = PropertiesForCode(data[5])
+	return err
+}
+
+// MarshalBinary encodes the chunk header value. The function checks
+// whether the content of the chunk header is correct.
+func (h *chunkHeader) MarshalBinary() (data []byte, err error) {
+	if h.ctype > cLRND {
+		return nil, errors.New("invalid chunk type")
+	}
+	if err = h.props.verify(); err != nil {
+		return nil, err
+	}
+
+	data = make([]byte, headerLen(h.ctype))
+
+	switch h.ctype {
+	case cEOS:
+		return data, nil
+	case cUD:
+		data[0] = hUD
+	case cU:
+		data[0] = hU
+	case cL:
+		data[0] = hL
+	case cLR:
+		data[0] = hLR
+	case cLRN:
+		data[0] = hLRN
+	case cLRND:
+		data[0] = hLRND
+	}
+
+	putUint16BE(data[1:3], uint16(h.uncompressed))
+	if h.ctype <= cU {
+		return data, nil
+	}
+	data[0] |= byte(h.uncompressed>>16) &^ hLRND
+
+	putUint16BE(data[3:5], h.compressed)
+	if h.ctype <= cLR {
+		return data, nil
+	}
+
+	data[5] = h.props.Code()
+	return data, nil
+}
+
+// readChunkHeader reads the chunk header from the IO reader.
+func readChunkHeader(r io.Reader) (h *chunkHeader, err error) {
+	p := make([]byte, 1, 6)
+	if _, err = io.ReadFull(r, p); err != nil {
+		return
+	}
+	c, err := headerChunkType(p[0])
+	if err != nil {
+		return
+	}
+	p = p[:headerLen(c)]
+	if _, err = io.ReadFull(r, p[1:]); err != nil {
+		return
+	}
+	h = new(chunkHeader)
+	if err = h.UnmarshalBinary(p); err != nil {
+		return nil, err
+	}
+	return h, nil
+}
+
+// uint16BE converts a big-endian uint16 representation to an uint16
+// value.
+func uint16BE(p []byte) uint16 {
+	return uint16(p[0])<<8 | uint16(p[1])
+}
+
+// putUint16BE puts the big-endian uint16 presentation into the given
+// slice.
+func putUint16BE(p []byte, x uint16) {
+	p[0] = byte(x >> 8)
+	p[1] = byte(x)
+}
+
+// chunkState is used to manage the state of the chunks
+type chunkState byte
+
+// start and stop define the initial and terminating state of the chunk
+// state
+const (
+	start chunkState = 'S'
+	stop             = 'T'
+)
+
+// errors for the chunk state handling
+var (
+	errChunkType = errors.New("lzma: unexpected chunk type")
+	errState     = errors.New("lzma: wrong chunk state")
+)
+
+// next transitions state based on chunk type input
+func (c *chunkState) next(ctype chunkType) error {
+	switch *c {
+	// start state
+	case 'S':
+		switch ctype {
+		case cEOS:
+			*c = 'T'
+		case cUD:
+			*c = 'R'
+		case cLRND:
+			*c = 'L'
+		default:
+			return errChunkType
+		}
+	// normal LZMA mode
+	case 'L':
+		switch ctype {
+		case cEOS:
+			*c = 'T'
+		case cUD:
+			*c = 'R'
+		case cU:
+			*c = 'U'
+		case cL, cLR, cLRN, cLRND:
+			break
+		default:
+			return errChunkType
+		}
+	// reset required
+	case 'R':
+		switch ctype {
+		case cEOS:
+			*c = 'T'
+		case cUD, cU:
+			break
+		case cLRN, cLRND:
+			*c = 'L'
+		default:
+			return errChunkType
+		}
+	// uncompressed
+	case 'U':
+		switch ctype {
+		case cEOS:
+			*c = 'T'
+		case cUD:
+			*c = 'R'
+		case cU:
+			break
+		case cL, cLR, cLRN, cLRND:
+			*c = 'L'
+		default:
+			return errChunkType
+		}
+	// terminal state
+	case 'T':
+		return errChunkType
+	default:
+		return errState
+	}
+	return nil
+}
+
+// defaultChunkType returns the default chunk type for each chunk state.
+func (c chunkState) defaultChunkType() chunkType {
+	switch c {
+	case 'S':
+		return cLRND
+	case 'L', 'U':
+		return cL
+	case 'R':
+		return cLRN
+	default:
+		// no error
+		return cEOS
+	}
+}
+
+// maxDictCap defines the maximum dictionary capacity supported by the
+// LZMA2 dictionary capacity encoding.
+const maxDictCap = 1<<32 - 1
+
+// maxDictCapCode defines the maximum dictionary capacity code.
+const maxDictCapCode = 40
+
+// The function decodes the dictionary capacity byte, but doesn't change
+// for the correct range of the given byte.
+func decodeDictCap(c byte) int64 {
+	return (2 | int64(c)&1) << (11 + (c>>1)&0x1f)
+}
+
+// DecodeDictCap decodes the encoded dictionary capacity. The function
+// returns an error if the code is out of range.
+func DecodeDictCap(c byte) (n int64, err error) {
+	if c >= maxDictCapCode {
+		if c == maxDictCapCode {
+			return maxDictCap, nil
+		}
+		return 0, errors.New("lzma: invalid dictionary size code")
+	}
+	return decodeDictCap(c), nil
+}
+
+// EncodeDictCap encodes a dictionary capacity. The function returns the
+// code for the capacity that is greater or equal n. If n exceeds the
+// maximum support dictionary capacity, the maximum value is returned.
+func EncodeDictCap(n int64) byte {
+	a, b := byte(0), byte(40)
+	for a < b {
+		c := a + (b-a)>>1
+		m := decodeDictCap(c)
+		if n <= m {
+			if n == m {
+				return c
+			}
+			b = c
+		} else {
+			a = c + 1
+		}
+	}
+	return a
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/lengthcodec.go b/vendor/github.com/ulikunitz/xz/lzma/lengthcodec.go
new file mode 100644
index 000000000..e51773092
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/lengthcodec.go
@@ -0,0 +1,129 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import "errors"
+
+// maxPosBits defines the number of bits of the position value that are used to
+// to compute the posState value. The value is used to select the tree codec
+// for length encoding and decoding.
+const maxPosBits = 4
+
+// minMatchLen and maxMatchLen give the minimum and maximum values for
+// encoding and decoding length values. minMatchLen is also used as base
+// for the encoded length values.
+const (
+	minMatchLen = 2
+	maxMatchLen = minMatchLen + 16 + 256 - 1
+)
+
+// lengthCodec support the encoding of the length value.
+type lengthCodec struct {
+	choice [2]prob
+	low    [1 << maxPosBits]treeCodec
+	mid    [1 << maxPosBits]treeCodec
+	high   treeCodec
+}
+
+// deepcopy initializes the lc value as deep copy of the source value.
+func (lc *lengthCodec) deepcopy(src *lengthCodec) {
+	if lc == src {
+		return
+	}
+	lc.choice = src.choice
+	for i := range lc.low {
+		lc.low[i].deepcopy(&src.low[i])
+	}
+	for i := range lc.mid {
+		lc.mid[i].deepcopy(&src.mid[i])
+	}
+	lc.high.deepcopy(&src.high)
+}
+
+// init initializes a new length codec.
+func (lc *lengthCodec) init() {
+	for i := range lc.choice {
+		lc.choice[i] = probInit
+	}
+	for i := range lc.low {
+		lc.low[i] = makeTreeCodec(3)
+	}
+	for i := range lc.mid {
+		lc.mid[i] = makeTreeCodec(3)
+	}
+	lc.high = makeTreeCodec(8)
+}
+
+// lBits gives the number of bits used for the encoding of the l value
+// provided to the range encoder.
+func lBits(l uint32) int {
+	switch {
+	case l < 8:
+		return 4
+	case l < 16:
+		return 5
+	default:
+		return 10
+	}
+}
+
+// Encode encodes the length offset. The length offset l can be compute by
+// subtracting minMatchLen (2) from the actual length.
+//
+//   l = length - minMatchLen
+//
+func (lc *lengthCodec) Encode(e *rangeEncoder, l uint32, posState uint32,
+) (err error) {
+	if l > maxMatchLen-minMatchLen {
+		return errors.New("lengthCodec.Encode: l out of range")
+	}
+	if l < 8 {
+		if err = lc.choice[0].Encode(e, 0); err != nil {
+			return
+		}
+		return lc.low[posState].Encode(e, l)
+	}
+	if err = lc.choice[0].Encode(e, 1); err != nil {
+		return
+	}
+	if l < 16 {
+		if err = lc.choice[1].Encode(e, 0); err != nil {
+			return
+		}
+		return lc.mid[posState].Encode(e, l-8)
+	}
+	if err = lc.choice[1].Encode(e, 1); err != nil {
+		return
+	}
+	if err = lc.high.Encode(e, l-16); err != nil {
+		return
+	}
+	return nil
+}
+
+// Decode reads the length offset. Add minMatchLen to compute the actual length
+// to the length offset l.
+func (lc *lengthCodec) Decode(d *rangeDecoder, posState uint32,
+) (l uint32, err error) {
+	var b uint32
+	if b, err = lc.choice[0].Decode(d); err != nil {
+		return
+	}
+	if b == 0 {
+		l, err = lc.low[posState].Decode(d)
+		return
+	}
+	if b, err = lc.choice[1].Decode(d); err != nil {
+		return
+	}
+	if b == 0 {
+		l, err = lc.mid[posState].Decode(d)
+		l += 8
+		return
+	}
+	l, err = lc.high.Decode(d)
+	l += 16
+	return
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/literalcodec.go b/vendor/github.com/ulikunitz/xz/lzma/literalcodec.go
new file mode 100644
index 000000000..c949d6ebd
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/literalcodec.go
@@ -0,0 +1,132 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+// literalCodec supports the encoding of literal. It provides 768 probability
+// values per literal state. The upper 512 probabilities are used with the
+// context of a match bit.
+type literalCodec struct {
+	probs []prob
+}
+
+// deepcopy initializes literal codec c as a deep copy of the source.
+func (c *literalCodec) deepcopy(src *literalCodec) {
+	if c == src {
+		return
+	}
+	c.probs = make([]prob, len(src.probs))
+	copy(c.probs, src.probs)
+}
+
+// init initializes the literal codec.
+func (c *literalCodec) init(lc, lp int) {
+	switch {
+	case !(minLC <= lc && lc <= maxLC):
+		panic("lc out of range")
+	case !(minLP <= lp && lp <= maxLP):
+		panic("lp out of range")
+	}
+	c.probs = make([]prob, 0x300<<uint(lc+lp))
+	for i := range c.probs {
+		c.probs[i] = probInit
+	}
+}
+
+// Encode encodes the byte s using a range encoder as well as the current LZMA
+// encoder state, a match byte and the literal state.
+func (c *literalCodec) Encode(e *rangeEncoder, s byte,
+	state uint32, match byte, litState uint32,
+) (err error) {
+	k := litState * 0x300
+	probs := c.probs[k : k+0x300]
+	symbol := uint32(1)
+	r := uint32(s)
+	if state >= 7 {
+		m := uint32(match)
+		for {
+			matchBit := (m >> 7) & 1
+			m <<= 1
+			bit := (r >> 7) & 1
+			r <<= 1
+			i := ((1 + matchBit) << 8) | symbol
+			if err = probs[i].Encode(e, bit); err != nil {
+				return
+			}
+			symbol = (symbol << 1) | bit
+			if matchBit != bit {
+				break
+			}
+			if symbol >= 0x100 {
+				break
+			}
+		}
+	}
+	for symbol < 0x100 {
+		bit := (r >> 7) & 1
+		r <<= 1
+		if err = probs[symbol].Encode(e, bit); err != nil {
+			return
+		}
+		symbol = (symbol << 1) | bit
+	}
+	return nil
+}
+
+// Decode decodes a literal byte using the range decoder as well as the LZMA
+// state, a match byte, and the literal state.
+func (c *literalCodec) Decode(d *rangeDecoder,
+	state uint32, match byte, litState uint32,
+) (s byte, err error) {
+	k := litState * 0x300
+	probs := c.probs[k : k+0x300]
+	symbol := uint32(1)
+	if state >= 7 {
+		m := uint32(match)
+		for {
+			matchBit := (m >> 7) & 1
+			m <<= 1
+			i := ((1 + matchBit) << 8) | symbol
+			bit, err := d.DecodeBit(&probs[i])
+			if err != nil {
+				return 0, err
+			}
+			symbol = (symbol << 1) | bit
+			if matchBit != bit {
+				break
+			}
+			if symbol >= 0x100 {
+				break
+			}
+		}
+	}
+	for symbol < 0x100 {
+		bit, err := d.DecodeBit(&probs[symbol])
+		if err != nil {
+			return 0, err
+		}
+		symbol = (symbol << 1) | bit
+	}
+	s = byte(symbol - 0x100)
+	return s, nil
+}
+
+// minLC and maxLC define the range for LC values.
+const (
+	minLC = 0
+	maxLC = 8
+)
+
+// minLC and maxLC define the range for LP values.
+const (
+	minLP = 0
+	maxLP = 4
+)
+
+// minState and maxState define a range for the state values stored in
+// the State values.
+const (
+	minState = 0
+	maxState = 11
+)
diff --git a/vendor/github.com/ulikunitz/xz/lzma/matchalgorithm.go b/vendor/github.com/ulikunitz/xz/lzma/matchalgorithm.go
new file mode 100644
index 000000000..4a244eb1a
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/matchalgorithm.go
@@ -0,0 +1,52 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import "errors"
+
+// MatchAlgorithm identifies an algorithm to find matches in the
+// dictionary.
+type MatchAlgorithm byte
+
+// Supported matcher algorithms.
+const (
+	HashTable4 MatchAlgorithm = iota
+	BinaryTree
+)
+
+// maStrings are used by the String method.
+var maStrings = map[MatchAlgorithm]string{
+	HashTable4: "HashTable4",
+	BinaryTree: "BinaryTree",
+}
+
+// String returns a string representation of the Matcher.
+func (a MatchAlgorithm) String() string {
+	if s, ok := maStrings[a]; ok {
+		return s
+	}
+	return "unknown"
+}
+
+var errUnsupportedMatchAlgorithm = errors.New(
+	"lzma: unsupported match algorithm value")
+
+// verify checks whether the matcher value is supported.
+func (a MatchAlgorithm) verify() error {
+	if _, ok := maStrings[a]; !ok {
+		return errUnsupportedMatchAlgorithm
+	}
+	return nil
+}
+
+func (a MatchAlgorithm) new(dictCap int) (m matcher, err error) {
+	switch a {
+	case HashTable4:
+		return newHashTable(dictCap, 4)
+	case BinaryTree:
+		return newBinTree(dictCap)
+	}
+	return nil, errUnsupportedMatchAlgorithm
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/operation.go b/vendor/github.com/ulikunitz/xz/lzma/operation.go
new file mode 100644
index 000000000..733bb99da
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/operation.go
@@ -0,0 +1,80 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"fmt"
+	"unicode"
+)
+
+// operation represents an operation on the dictionary during encoding or
+// decoding.
+type operation interface {
+	Len() int
+}
+
+// rep represents a repetition at the given distance and the given length
+type match struct {
+	// supports all possible distance values, including the eos marker
+	distance int64
+	// length
+	n int
+}
+
+// verify checks whether the match is valid. If that is not the case an
+// error is returned.
+func (m match) verify() error {
+	if !(minDistance <= m.distance && m.distance <= maxDistance) {
+		return errors.New("distance out of range")
+	}
+	if !(1 <= m.n && m.n <= maxMatchLen) {
+		return errors.New("length out of range")
+	}
+	return nil
+}
+
+// l return the l-value for the match, which is the difference of length
+// n and 2.
+func (m match) l() uint32 {
+	return uint32(m.n - minMatchLen)
+}
+
+// dist returns the dist value for the match, which is one less of the
+// distance stored in the match.
+func (m match) dist() uint32 {
+	return uint32(m.distance - minDistance)
+}
+
+// Len returns the number of bytes matched.
+func (m match) Len() int {
+	return m.n
+}
+
+// String returns a string representation for the repetition.
+func (m match) String() string {
+	return fmt.Sprintf("M{%d,%d}", m.distance, m.n)
+}
+
+// lit represents a single byte literal.
+type lit struct {
+	b byte
+}
+
+// Len returns 1 for the single byte literal.
+func (l lit) Len() int {
+	return 1
+}
+
+// String returns a string representation for the literal.
+func (l lit) String() string {
+	var c byte
+	if unicode.IsPrint(rune(l.b)) {
+		c = l.b
+	} else {
+		c = '.'
+	}
+	return fmt.Sprintf("L{%c/%02x}", c, l.b)
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/prob.go b/vendor/github.com/ulikunitz/xz/lzma/prob.go
new file mode 100644
index 000000000..24d50ec68
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/prob.go
@@ -0,0 +1,53 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+// movebits defines the number of bits used for the updates of probability
+// values.
+const movebits = 5
+
+// probbits defines the number of bits of a probability value.
+const probbits = 11
+
+// probInit defines 0.5 as initial value for prob values.
+const probInit prob = 1 << (probbits - 1)
+
+// Type prob represents probabilities. The type can also be used to encode and
+// decode single bits.
+type prob uint16
+
+// Dec decreases the probability. The decrease is proportional to the
+// probability value.
+func (p *prob) dec() {
+	*p -= *p >> movebits
+}
+
+// Inc increases the probability. The Increase is proportional to the
+// difference of 1 and the probability value.
+func (p *prob) inc() {
+	*p += ((1 << probbits) - *p) >> movebits
+}
+
+// Computes the new bound for a given range using the probability value.
+func (p prob) bound(r uint32) uint32 {
+	return (r >> probbits) * uint32(p)
+}
+
+// Bits returns 1. One is the number of bits that can be encoded or decoded
+// with a single prob value.
+func (p prob) Bits() int {
+	return 1
+}
+
+// Encode encodes the least-significant bit of v. Note that the p value will be
+// changed.
+func (p *prob) Encode(e *rangeEncoder, v uint32) error {
+	return e.EncodeBit(v, p)
+}
+
+// Decode decodes a single bit. Note that the p value will change.
+func (p *prob) Decode(d *rangeDecoder) (v uint32, err error) {
+	return d.DecodeBit(p)
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/properties.go b/vendor/github.com/ulikunitz/xz/lzma/properties.go
new file mode 100644
index 000000000..23418e25d
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/properties.go
@@ -0,0 +1,69 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"fmt"
+)
+
+// maximum and minimum values for the LZMA properties.
+const (
+	minPB = 0
+	maxPB = 4
+)
+
+// maxPropertyCode is the possible maximum of a properties code byte.
+const maxPropertyCode = (maxPB+1)*(maxLP+1)*(maxLC+1) - 1
+
+// Properties contains the parameters LC, LP and PB. The parameter LC
+// defines the number of literal context bits; parameter LP the number
+// of literal position bits and PB the number of position bits.
+type Properties struct {
+	LC int
+	LP int
+	PB int
+}
+
+// String returns the properties in a string representation.
+func (p *Properties) String() string {
+	return fmt.Sprintf("LC %d LP %d PB %d", p.LC, p.LP, p.PB)
+}
+
+// PropertiesForCode converts a properties code byte into a Properties value.
+func PropertiesForCode(code byte) (p Properties, err error) {
+	if code > maxPropertyCode {
+		return p, errors.New("lzma: invalid properties code")
+	}
+	p.LC = int(code % 9)
+	code /= 9
+	p.LP = int(code % 5)
+	code /= 5
+	p.PB = int(code % 5)
+	return p, err
+}
+
+// verify checks the properties for correctness.
+func (p *Properties) verify() error {
+	if p == nil {
+		return errors.New("lzma: properties are nil")
+	}
+	if !(minLC <= p.LC && p.LC <= maxLC) {
+		return errors.New("lzma: lc out of range")
+	}
+	if !(minLP <= p.LP && p.LP <= maxLP) {
+		return errors.New("lzma: lp out of range")
+	}
+	if !(minPB <= p.PB && p.PB <= maxPB) {
+		return errors.New("lzma: pb out of range")
+	}
+	return nil
+}
+
+// Code converts the properties to a byte. The function assumes that
+// the properties components are all in range.
+func (p Properties) Code() byte {
+	return byte((p.PB*5+p.LP)*9 + p.LC)
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/rangecodec.go b/vendor/github.com/ulikunitz/xz/lzma/rangecodec.go
new file mode 100644
index 000000000..6361c5e7c
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/rangecodec.go
@@ -0,0 +1,248 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"io"
+)
+
+// rangeEncoder implements range encoding of single bits. The low value can
+// overflow therefore we need uint64. The cache value is used to handle
+// overflows.
+type rangeEncoder struct {
+	lbw      *LimitedByteWriter
+	nrange   uint32
+	low      uint64
+	cacheLen int64
+	cache    byte
+}
+
+// maxInt64 provides the  maximal value of the int64 type
+const maxInt64 = 1<<63 - 1
+
+// newRangeEncoder creates a new range encoder.
+func newRangeEncoder(bw io.ByteWriter) (re *rangeEncoder, err error) {
+	lbw, ok := bw.(*LimitedByteWriter)
+	if !ok {
+		lbw = &LimitedByteWriter{BW: bw, N: maxInt64}
+	}
+	return &rangeEncoder{
+		lbw:      lbw,
+		nrange:   0xffffffff,
+		cacheLen: 1}, nil
+}
+
+// Available returns the number of bytes that still can be written. The
+// method takes the bytes that will be currently written by Close into
+// account.
+func (e *rangeEncoder) Available() int64 {
+	return e.lbw.N - (e.cacheLen + 4)
+}
+
+// writeByte writes a single byte to the underlying writer. An error is
+// returned if the limit is reached. The written byte will be counted if
+// the underlying writer doesn't return an error.
+func (e *rangeEncoder) writeByte(c byte) error {
+	if e.Available() < 1 {
+		return ErrLimit
+	}
+	return e.lbw.WriteByte(c)
+}
+
+// DirectEncodeBit encodes the least-significant bit of b with probability 1/2.
+func (e *rangeEncoder) DirectEncodeBit(b uint32) error {
+	e.nrange >>= 1
+	e.low += uint64(e.nrange) & (0 - (uint64(b) & 1))
+
+	// normalize
+	const top = 1 << 24
+	if e.nrange >= top {
+		return nil
+	}
+	e.nrange <<= 8
+	return e.shiftLow()
+}
+
+// EncodeBit encodes the least significant bit of b. The p value will be
+// updated by the function depending on the bit encoded.
+func (e *rangeEncoder) EncodeBit(b uint32, p *prob) error {
+	bound := p.bound(e.nrange)
+	if b&1 == 0 {
+		e.nrange = bound
+		p.inc()
+	} else {
+		e.low += uint64(bound)
+		e.nrange -= bound
+		p.dec()
+	}
+
+	// normalize
+	const top = 1 << 24
+	if e.nrange >= top {
+		return nil
+	}
+	e.nrange <<= 8
+	return e.shiftLow()
+}
+
+// Close writes a complete copy of the low value.
+func (e *rangeEncoder) Close() error {
+	for i := 0; i < 5; i++ {
+		if err := e.shiftLow(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// shiftLow shifts the low value for 8 bit. The shifted byte is written into
+// the byte writer. The cache value is used to handle overflows.
+func (e *rangeEncoder) shiftLow() error {
+	if uint32(e.low) < 0xff000000 || (e.low>>32) != 0 {
+		tmp := e.cache
+		for {
+			err := e.writeByte(tmp + byte(e.low>>32))
+			if err != nil {
+				return err
+			}
+			tmp = 0xff
+			e.cacheLen--
+			if e.cacheLen <= 0 {
+				if e.cacheLen < 0 {
+					panic("negative cacheLen")
+				}
+				break
+			}
+		}
+		e.cache = byte(uint32(e.low) >> 24)
+	}
+	e.cacheLen++
+	e.low = uint64(uint32(e.low) << 8)
+	return nil
+}
+
+// rangeDecoder decodes single bits of the range encoding stream.
+type rangeDecoder struct {
+	br     io.ByteReader
+	nrange uint32
+	code   uint32
+}
+
+// init initializes the range decoder, by reading from the byte reader.
+func (d *rangeDecoder) init() error {
+	d.nrange = 0xffffffff
+	d.code = 0
+
+	b, err := d.br.ReadByte()
+	if err != nil {
+		return err
+	}
+	if b != 0 {
+		return errors.New("newRangeDecoder: first byte not zero")
+	}
+
+	for i := 0; i < 4; i++ {
+		if err = d.updateCode(); err != nil {
+			return err
+		}
+	}
+
+	if d.code >= d.nrange {
+		return errors.New("newRangeDecoder: d.code >= d.nrange")
+	}
+
+	return nil
+}
+
+// newRangeDecoder initializes a range decoder. It reads five bytes from the
+// reader and therefore may return an error.
+func newRangeDecoder(br io.ByteReader) (d *rangeDecoder, err error) {
+	d = &rangeDecoder{br: br, nrange: 0xffffffff}
+
+	b, err := d.br.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+	if b != 0 {
+		return nil, errors.New("newRangeDecoder: first byte not zero")
+	}
+
+	for i := 0; i < 4; i++ {
+		if err = d.updateCode(); err != nil {
+			return nil, err
+		}
+	}
+
+	if d.code >= d.nrange {
+		return nil, errors.New("newRangeDecoder: d.code >= d.nrange")
+	}
+
+	return d, nil
+}
+
+// possiblyAtEnd checks whether the decoder may be at the end of the stream.
+func (d *rangeDecoder) possiblyAtEnd() bool {
+	return d.code == 0
+}
+
+// DirectDecodeBit decodes a bit with probability 1/2. The return value b will
+// contain the bit at the least-significant position. All other bits will be
+// zero.
+func (d *rangeDecoder) DirectDecodeBit() (b uint32, err error) {
+	d.nrange >>= 1
+	d.code -= d.nrange
+	t := 0 - (d.code >> 31)
+	d.code += d.nrange & t
+	b = (t + 1) & 1
+
+	// d.code will stay less then d.nrange
+
+	// normalize
+	// assume d.code < d.nrange
+	const top = 1 << 24
+	if d.nrange >= top {
+		return b, nil
+	}
+	d.nrange <<= 8
+	// d.code < d.nrange will be maintained
+	return b, d.updateCode()
+}
+
+// decodeBit decodes a single bit. The bit will be returned at the
+// least-significant position. All other bits will be zero. The probability
+// value will be updated.
+func (d *rangeDecoder) DecodeBit(p *prob) (b uint32, err error) {
+	bound := p.bound(d.nrange)
+	if d.code < bound {
+		d.nrange = bound
+		p.inc()
+		b = 0
+	} else {
+		d.code -= bound
+		d.nrange -= bound
+		p.dec()
+		b = 1
+	}
+	// normalize
+	// assume d.code < d.nrange
+	const top = 1 << 24
+	if d.nrange >= top {
+		return b, nil
+	}
+	d.nrange <<= 8
+	// d.code < d.nrange will be maintained
+	return b, d.updateCode()
+}
+
+// updateCode reads a new byte into the code.
+func (d *rangeDecoder) updateCode() error {
+	b, err := d.br.ReadByte()
+	if err != nil {
+		return err
+	}
+	d.code = (d.code << 8) | uint32(b)
+	return nil
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/reader.go b/vendor/github.com/ulikunitz/xz/lzma/reader.go
new file mode 100644
index 000000000..2ef3dcaaa
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/reader.go
@@ -0,0 +1,100 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package lzma supports the decoding and encoding of LZMA streams.
+// Reader and Writer support the classic LZMA format. Reader2 and
+// Writer2 support the decoding and encoding of LZMA2 streams.
+//
+// The package is written completely in Go and doesn't rely on any external
+// library.
+package lzma
+
+import (
+	"errors"
+	"io"
+)
+
+// ReaderConfig stores the parameters for the reader of the classic LZMA
+// format.
+type ReaderConfig struct {
+	DictCap int
+}
+
+// fill converts the zero values of the configuration to the default values.
+func (c *ReaderConfig) fill() {
+	if c.DictCap == 0 {
+		c.DictCap = 8 * 1024 * 1024
+	}
+}
+
+// Verify checks the reader configuration for errors. Zero values will
+// be replaced by default values.
+func (c *ReaderConfig) Verify() error {
+	c.fill()
+	if !(MinDictCap <= c.DictCap && int64(c.DictCap) <= MaxDictCap) {
+		return errors.New("lzma: dictionary capacity is out of range")
+	}
+	return nil
+}
+
+// Reader provides a reader for LZMA files or streams.
+type Reader struct {
+	lzma io.Reader
+	h    header
+	d    *decoder
+}
+
+// NewReader creates a new reader for an LZMA stream using the classic
+// format. NewReader reads and checks the header of the LZMA stream.
+func NewReader(lzma io.Reader) (r *Reader, err error) {
+	return ReaderConfig{}.NewReader(lzma)
+}
+
+// NewReader creates a new reader for an LZMA stream in the classic
+// format. The function reads and verifies the the header of the LZMA
+// stream.
+func (c ReaderConfig) NewReader(lzma io.Reader) (r *Reader, err error) {
+	if err = c.Verify(); err != nil {
+		return nil, err
+	}
+	data := make([]byte, HeaderLen)
+	if _, err := io.ReadFull(lzma, data); err != nil {
+		if err == io.EOF {
+			return nil, errors.New("lzma: unexpected EOF")
+		}
+		return nil, err
+	}
+	r = &Reader{lzma: lzma}
+	if err = r.h.unmarshalBinary(data); err != nil {
+		return nil, err
+	}
+	if r.h.dictCap < MinDictCap {
+		return nil, errors.New("lzma: dictionary capacity too small")
+	}
+	dictCap := r.h.dictCap
+	if c.DictCap > dictCap {
+		dictCap = c.DictCap
+	}
+
+	state := newState(r.h.properties)
+	dict, err := newDecoderDict(dictCap)
+	if err != nil {
+		return nil, err
+	}
+	r.d, err = newDecoder(ByteReader(lzma), state, dict, r.h.size)
+	if err != nil {
+		return nil, err
+	}
+	return r, nil
+}
+
+// EOSMarker indicates that an EOS marker has been encountered.
+func (r *Reader) EOSMarker() bool {
+	return r.d.eosMarker
+}
+
+// Read returns uncompressed data.
+func (r *Reader) Read(p []byte) (n int, err error) {
+	return r.d.Read(p)
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/reader2.go b/vendor/github.com/ulikunitz/xz/lzma/reader2.go
new file mode 100644
index 000000000..a55cfaa4e
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/reader2.go
@@ -0,0 +1,232 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"errors"
+	"io"
+
+	"github.com/ulikunitz/xz/internal/xlog"
+)
+
+// Reader2Config stores the parameters for the LZMA2 reader.
+// format.
+type Reader2Config struct {
+	DictCap int
+}
+
+// fill converts the zero values of the configuration to the default values.
+func (c *Reader2Config) fill() {
+	if c.DictCap == 0 {
+		c.DictCap = 8 * 1024 * 1024
+	}
+}
+
+// Verify checks the reader configuration for errors. Zero configuration values
+// will be replaced by default values.
+func (c *Reader2Config) Verify() error {
+	c.fill()
+	if !(MinDictCap <= c.DictCap && int64(c.DictCap) <= MaxDictCap) {
+		return errors.New("lzma: dictionary capacity is out of range")
+	}
+	return nil
+}
+
+// Reader2 supports the reading of LZMA2 chunk sequences. Note that the
+// first chunk should have a dictionary reset and the first compressed
+// chunk a properties reset. The chunk sequence may not be terminated by
+// an end-of-stream chunk.
+type Reader2 struct {
+	r   io.Reader
+	err error
+
+	dict        *decoderDict
+	ur          *uncompressedReader
+	decoder     *decoder
+	chunkReader io.Reader
+
+	cstate chunkState
+	ctype  chunkType
+}
+
+// NewReader2 creates a reader for an LZMA2 chunk sequence.
+func NewReader2(lzma2 io.Reader) (r *Reader2, err error) {
+	return Reader2Config{}.NewReader2(lzma2)
+}
+
+// NewReader2 creates an LZMA2 reader using the given configuration.
+func (c Reader2Config) NewReader2(lzma2 io.Reader) (r *Reader2, err error) {
+	if err = c.Verify(); err != nil {
+		return nil, err
+	}
+	r = &Reader2{r: lzma2, cstate: start}
+	r.dict, err = newDecoderDict(c.DictCap)
+	if err != nil {
+		return nil, err
+	}
+	if err = r.startChunk(); err != nil {
+		r.err = err
+	}
+	return r, nil
+}
+
+// uncompressed tests whether the chunk type specifies an uncompressed
+// chunk.
+func uncompressed(ctype chunkType) bool {
+	return ctype == cU || ctype == cUD
+}
+
+// startChunk parses a new chunk.
+func (r *Reader2) startChunk() error {
+	r.chunkReader = nil
+	header, err := readChunkHeader(r.r)
+	if err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
+		return err
+	}
+	xlog.Debugf("chunk header %v", header)
+	if err = r.cstate.next(header.ctype); err != nil {
+		return err
+	}
+	if r.cstate == stop {
+		return io.EOF
+	}
+	if header.ctype == cUD || header.ctype == cLRND {
+		r.dict.Reset()
+	}
+	size := int64(header.uncompressed) + 1
+	if uncompressed(header.ctype) {
+		if r.ur != nil {
+			r.ur.Reopen(r.r, size)
+		} else {
+			r.ur = newUncompressedReader(r.r, r.dict, size)
+		}
+		r.chunkReader = r.ur
+		return nil
+	}
+	br := ByteReader(io.LimitReader(r.r, int64(header.compressed)+1))
+	if r.decoder == nil {
+		state := newState(header.props)
+		r.decoder, err = newDecoder(br, state, r.dict, size)
+		if err != nil {
+			return err
+		}
+		r.chunkReader = r.decoder
+		return nil
+	}
+	switch header.ctype {
+	case cLR:
+		r.decoder.State.Reset()
+	case cLRN, cLRND:
+		r.decoder.State = newState(header.props)
+	}
+	err = r.decoder.Reopen(br, size)
+	if err != nil {
+		return err
+	}
+	r.chunkReader = r.decoder
+	return nil
+}
+
+// Read reads data from the LZMA2 chunk sequence.
+func (r *Reader2) Read(p []byte) (n int, err error) {
+	if r.err != nil {
+		return 0, r.err
+	}
+	for n < len(p) {
+		var k int
+		k, err = r.chunkReader.Read(p[n:])
+		n += k
+		if err != nil {
+			if err == io.EOF {
+				err = r.startChunk()
+				if err == nil {
+					continue
+				}
+			}
+			r.err = err
+			return n, err
+		}
+		if k == 0 {
+			r.err = errors.New("lzma: Reader2 doesn't get data")
+			return n, r.err
+		}
+	}
+	return n, nil
+}
+
+// EOS returns whether the LZMA2 stream has been terminated by an
+// end-of-stream chunk.
+func (r *Reader2) EOS() bool {
+	return r.cstate == stop
+}
+
+// uncompressedReader is used to read uncompressed chunks.
+type uncompressedReader struct {
+	lr   io.LimitedReader
+	Dict *decoderDict
+	eof  bool
+	err  error
+}
+
+// newUncompressedReader initializes a new uncompressedReader.
+func newUncompressedReader(r io.Reader, dict *decoderDict, size int64) *uncompressedReader {
+	ur := &uncompressedReader{
+		lr:   io.LimitedReader{R: r, N: size},
+		Dict: dict,
+	}
+	return ur
+}
+
+// Reopen reinitializes an uncompressed reader.
+func (ur *uncompressedReader) Reopen(r io.Reader, size int64) {
+	ur.err = nil
+	ur.eof = false
+	ur.lr = io.LimitedReader{R: r, N: size}
+}
+
+// fill reads uncompressed data into the dictionary.
+func (ur *uncompressedReader) fill() error {
+	if !ur.eof {
+		n, err := io.CopyN(ur.Dict, &ur.lr, int64(ur.Dict.Available()))
+		if err != io.EOF {
+			return err
+		}
+		ur.eof = true
+		if n > 0 {
+			return nil
+		}
+	}
+	if ur.lr.N != 0 {
+		return io.ErrUnexpectedEOF
+	}
+	return io.EOF
+}
+
+// Read reads uncompressed data from the limited reader.
+func (ur *uncompressedReader) Read(p []byte) (n int, err error) {
+	if ur.err != nil {
+		return 0, ur.err
+	}
+	for {
+		var k int
+		k, err = ur.Dict.Read(p[n:])
+		n += k
+		if n >= len(p) {
+			return n, nil
+		}
+		if err != nil {
+			break
+		}
+		err = ur.fill()
+		if err != nil {
+			break
+		}
+	}
+	ur.err = err
+	return n, err
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/state.go b/vendor/github.com/ulikunitz/xz/lzma/state.go
new file mode 100644
index 000000000..502351052
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/state.go
@@ -0,0 +1,151 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+// states defines the overall state count
+const states = 12
+
+// State maintains the full state of the operation encoding or decoding
+// process.
+type state struct {
+	rep         [4]uint32
+	isMatch     [states << maxPosBits]prob
+	isRepG0Long [states << maxPosBits]prob
+	isRep       [states]prob
+	isRepG0     [states]prob
+	isRepG1     [states]prob
+	isRepG2     [states]prob
+	litCodec    literalCodec
+	lenCodec    lengthCodec
+	repLenCodec lengthCodec
+	distCodec   distCodec
+	state       uint32
+	posBitMask  uint32
+	Properties  Properties
+}
+
+// initProbSlice initializes a slice of probabilities.
+func initProbSlice(p []prob) {
+	for i := range p {
+		p[i] = probInit
+	}
+}
+
+// Reset sets all state information to the original values.
+func (s *state) Reset() {
+	p := s.Properties
+	*s = state{
+		Properties: p,
+		// dict:       s.dict,
+		posBitMask: (uint32(1) << uint(p.PB)) - 1,
+	}
+	initProbSlice(s.isMatch[:])
+	initProbSlice(s.isRep[:])
+	initProbSlice(s.isRepG0[:])
+	initProbSlice(s.isRepG1[:])
+	initProbSlice(s.isRepG2[:])
+	initProbSlice(s.isRepG0Long[:])
+	s.litCodec.init(p.LC, p.LP)
+	s.lenCodec.init()
+	s.repLenCodec.init()
+	s.distCodec.init()
+}
+
+// initState initializes the state.
+func initState(s *state, p Properties) {
+	*s = state{Properties: p}
+	s.Reset()
+}
+
+// newState creates a new state from the give Properties.
+func newState(p Properties) *state {
+	s := &state{Properties: p}
+	s.Reset()
+	return s
+}
+
+// deepcopy initializes s as a deep copy of the source.
+func (s *state) deepcopy(src *state) {
+	if s == src {
+		return
+	}
+	s.rep = src.rep
+	s.isMatch = src.isMatch
+	s.isRepG0Long = src.isRepG0Long
+	s.isRep = src.isRep
+	s.isRepG0 = src.isRepG0
+	s.isRepG1 = src.isRepG1
+	s.isRepG2 = src.isRepG2
+	s.litCodec.deepcopy(&src.litCodec)
+	s.lenCodec.deepcopy(&src.lenCodec)
+	s.repLenCodec.deepcopy(&src.repLenCodec)
+	s.distCodec.deepcopy(&src.distCodec)
+	s.state = src.state
+	s.posBitMask = src.posBitMask
+	s.Properties = src.Properties
+}
+
+// cloneState creates a new clone of the give state.
+func cloneState(src *state) *state {
+	s := new(state)
+	s.deepcopy(src)
+	return s
+}
+
+// updateStateLiteral updates the state for a literal.
+func (s *state) updateStateLiteral() {
+	switch {
+	case s.state < 4:
+		s.state = 0
+		return
+	case s.state < 10:
+		s.state -= 3
+		return
+	}
+	s.state -= 6
+}
+
+// updateStateMatch updates the state for a match.
+func (s *state) updateStateMatch() {
+	if s.state < 7 {
+		s.state = 7
+	} else {
+		s.state = 10
+	}
+}
+
+// updateStateRep updates the state for a repetition.
+func (s *state) updateStateRep() {
+	if s.state < 7 {
+		s.state = 8
+	} else {
+		s.state = 11
+	}
+}
+
+// updateStateShortRep updates the state for a short repetition.
+func (s *state) updateStateShortRep() {
+	if s.state < 7 {
+		s.state = 9
+	} else {
+		s.state = 11
+	}
+}
+
+// states computes the states of the operation codec.
+func (s *state) states(dictHead int64) (state1, state2, posState uint32) {
+	state1 = s.state
+	posState = uint32(dictHead) & s.posBitMask
+	state2 = (s.state << maxPosBits) | posState
+	return
+}
+
+// litState computes the literal state.
+func (s *state) litState(prev byte, dictHead int64) uint32 {
+	lp, lc := uint(s.Properties.LP), uint(s.Properties.LC)
+	litState := ((uint32(dictHead) & ((1 << lp) - 1)) << lc) |
+		(uint32(prev) >> (8 - lc))
+	return litState
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/treecodecs.go b/vendor/github.com/ulikunitz/xz/lzma/treecodecs.go
new file mode 100644
index 000000000..504b3d78e
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/treecodecs.go
@@ -0,0 +1,133 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+// treeCodec encodes or decodes values with a fixed bit size. It is using a
+// tree of probability value. The root of the tree is the most-significant bit.
+type treeCodec struct {
+	probTree
+}
+
+// makeTreeCodec makes a tree codec. The bits value must be inside the range
+// [1,32].
+func makeTreeCodec(bits int) treeCodec {
+	return treeCodec{makeProbTree(bits)}
+}
+
+// deepcopy initializes tc as a deep copy of the source.
+func (tc *treeCodec) deepcopy(src *treeCodec) {
+	tc.probTree.deepcopy(&src.probTree)
+}
+
+// Encode uses the range encoder to encode a fixed-bit-size value.
+func (tc *treeCodec) Encode(e *rangeEncoder, v uint32) (err error) {
+	m := uint32(1)
+	for i := int(tc.bits) - 1; i >= 0; i-- {
+		b := (v >> uint(i)) & 1
+		if err := e.EncodeBit(b, &tc.probs[m]); err != nil {
+			return err
+		}
+		m = (m << 1) | b
+	}
+	return nil
+}
+
+// Decodes uses the range decoder to decode a fixed-bit-size value. Errors may
+// be caused by the range decoder.
+func (tc *treeCodec) Decode(d *rangeDecoder) (v uint32, err error) {
+	m := uint32(1)
+	for j := 0; j < int(tc.bits); j++ {
+		b, err := d.DecodeBit(&tc.probs[m])
+		if err != nil {
+			return 0, err
+		}
+		m = (m << 1) | b
+	}
+	return m - (1 << uint(tc.bits)), nil
+}
+
+// treeReverseCodec is another tree codec, where the least-significant bit is
+// the start of the probability tree.
+type treeReverseCodec struct {
+	probTree
+}
+
+// deepcopy initializes the treeReverseCodec as a deep copy of the
+// source.
+func (tc *treeReverseCodec) deepcopy(src *treeReverseCodec) {
+	tc.probTree.deepcopy(&src.probTree)
+}
+
+// makeTreeReverseCodec creates treeReverseCodec value. The bits argument must
+// be in the range [1,32].
+func makeTreeReverseCodec(bits int) treeReverseCodec {
+	return treeReverseCodec{makeProbTree(bits)}
+}
+
+// Encode uses range encoder to encode a fixed-bit-size value. The range
+// encoder may cause errors.
+func (tc *treeReverseCodec) Encode(v uint32, e *rangeEncoder) (err error) {
+	m := uint32(1)
+	for i := uint(0); i < uint(tc.bits); i++ {
+		b := (v >> i) & 1
+		if err := e.EncodeBit(b, &tc.probs[m]); err != nil {
+			return err
+		}
+		m = (m << 1) | b
+	}
+	return nil
+}
+
+// Decodes uses the range decoder to decode a fixed-bit-size value. Errors
+// returned by the range decoder will be returned.
+func (tc *treeReverseCodec) Decode(d *rangeDecoder) (v uint32, err error) {
+	m := uint32(1)
+	for j := uint(0); j < uint(tc.bits); j++ {
+		b, err := d.DecodeBit(&tc.probs[m])
+		if err != nil {
+			return 0, err
+		}
+		m = (m << 1) | b
+		v |= b << j
+	}
+	return v, nil
+}
+
+// probTree stores enough probability values to be used by the treeEncode and
+// treeDecode methods of the range coder types.
+type probTree struct {
+	probs []prob
+	bits  byte
+}
+
+// deepcopy initializes the probTree value as a deep copy of the source.
+func (t *probTree) deepcopy(src *probTree) {
+	if t == src {
+		return
+	}
+	t.probs = make([]prob, len(src.probs))
+	copy(t.probs, src.probs)
+	t.bits = src.bits
+}
+
+// makeProbTree initializes a probTree structure.
+func makeProbTree(bits int) probTree {
+	if !(1 <= bits && bits <= 32) {
+		panic("bits outside of range [1,32]")
+	}
+	t := probTree{
+		bits:  byte(bits),
+		probs: make([]prob, 1<<uint(bits)),
+	}
+	for i := range t.probs {
+		t.probs[i] = probInit
+	}
+	return t
+}
+
+// Bits provides the number of bits for the values to de- or encode.
+func (t *probTree) Bits() int {
+	return int(t.bits)
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/writer.go b/vendor/github.com/ulikunitz/xz/lzma/writer.go
new file mode 100644
index 000000000..efe34fb6b
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/writer.go
@@ -0,0 +1,209 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"bufio"
+	"errors"
+	"io"
+)
+
+// MinDictCap and MaxDictCap provide the range of supported dictionary
+// capacities.
+const (
+	MinDictCap = 1 << 12
+	MaxDictCap = 1<<32 - 1
+)
+
+// WriterConfig defines the configuration parameter for a writer.
+type WriterConfig struct {
+	// Properties for the encoding. If the it is nil the value
+	// {LC: 3, LP: 0, PB: 2} will be chosen.
+	Properties *Properties
+	// The capacity of the dictionary. If DictCap is zero, the value
+	// 8 MiB will be chosen.
+	DictCap int
+	// Size of the lookahead buffer; value 0 indicates default size
+	// 4096
+	BufSize int
+	// Match algorithm
+	Matcher MatchAlgorithm
+	// SizeInHeader indicates that the header will contain an
+	// explicit size.
+	SizeInHeader bool
+	// Size of the data to be encoded. A positive value will imply
+	// than an explicit size will be set in the header.
+	Size int64
+	// EOSMarker requests whether the EOSMarker needs to be written.
+	// If no explicit size is been given the EOSMarker will be
+	// set automatically.
+	EOSMarker bool
+}
+
+// fill converts zero-value fields to their explicit default values.
+func (c *WriterConfig) fill() {
+	if c.Properties == nil {
+		c.Properties = &Properties{LC: 3, LP: 0, PB: 2}
+	}
+	if c.DictCap == 0 {
+		c.DictCap = 8 * 1024 * 1024
+	}
+	if c.BufSize == 0 {
+		c.BufSize = 4096
+	}
+	if c.Size > 0 {
+		c.SizeInHeader = true
+	}
+	if !c.SizeInHeader {
+		c.EOSMarker = true
+	}
+}
+
+// Verify checks WriterConfig for errors. Verify will replace zero
+// values with default values.
+func (c *WriterConfig) Verify() error {
+	c.fill()
+	var err error
+	if c == nil {
+		return errors.New("lzma: WriterConfig is nil")
+	}
+	if c.Properties == nil {
+		return errors.New("lzma: WriterConfig has no Properties set")
+	}
+	if err = c.Properties.verify(); err != nil {
+		return err
+	}
+	if !(MinDictCap <= c.DictCap && int64(c.DictCap) <= MaxDictCap) {
+		return errors.New("lzma: dictionary capacity is out of range")
+	}
+	if !(maxMatchLen <= c.BufSize) {
+		return errors.New("lzma: lookahead buffer size too small")
+	}
+	if c.SizeInHeader {
+		if c.Size < 0 {
+			return errors.New("lzma: negative size not supported")
+		}
+	} else if !c.EOSMarker {
+		return errors.New("lzma: EOS marker is required")
+	}
+	if err = c.Matcher.verify(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// header returns the header structure for this configuration.
+func (c *WriterConfig) header() header {
+	h := header{
+		properties: *c.Properties,
+		dictCap:    c.DictCap,
+		size:       -1,
+	}
+	if c.SizeInHeader {
+		h.size = c.Size
+	}
+	return h
+}
+
+// Writer writes an LZMA stream in the classic format.
+type Writer struct {
+	h   header
+	bw  io.ByteWriter
+	buf *bufio.Writer
+	e   *encoder
+}
+
+// NewWriter creates a new LZMA writer for the classic format. The
+// method will write the header to the underlying stream.
+func (c WriterConfig) NewWriter(lzma io.Writer) (w *Writer, err error) {
+	if err = c.Verify(); err != nil {
+		return nil, err
+	}
+	w = &Writer{h: c.header()}
+
+	var ok bool
+	w.bw, ok = lzma.(io.ByteWriter)
+	if !ok {
+		w.buf = bufio.NewWriter(lzma)
+		w.bw = w.buf
+	}
+	state := newState(w.h.properties)
+	m, err := c.Matcher.new(w.h.dictCap)
+	if err != nil {
+		return nil, err
+	}
+	dict, err := newEncoderDict(w.h.dictCap, c.BufSize, m)
+	if err != nil {
+		return nil, err
+	}
+	var flags encoderFlags
+	if c.EOSMarker {
+		flags = eosMarker
+	}
+	if w.e, err = newEncoder(w.bw, state, dict, flags); err != nil {
+		return nil, err
+	}
+
+	if err = w.writeHeader(); err != nil {
+		return nil, err
+	}
+	return w, nil
+}
+
+// NewWriter creates a new LZMA writer using the classic format. The
+// function writes the header to the underlying stream.
+func NewWriter(lzma io.Writer) (w *Writer, err error) {
+	return WriterConfig{}.NewWriter(lzma)
+}
+
+// writeHeader writes the LZMA header into the stream.
+func (w *Writer) writeHeader() error {
+	data, err := w.h.marshalBinary()
+	if err != nil {
+		return err
+	}
+	_, err = w.bw.(io.Writer).Write(data)
+	return err
+}
+
+// Write puts data into the Writer.
+func (w *Writer) Write(p []byte) (n int, err error) {
+	if w.h.size >= 0 {
+		m := w.h.size
+		m -= w.e.Compressed() + int64(w.e.dict.Buffered())
+		if m < 0 {
+			m = 0
+		}
+		if m < int64(len(p)) {
+			p = p[:m]
+			err = ErrNoSpace
+		}
+	}
+	var werr error
+	if n, werr = w.e.Write(p); werr != nil {
+		err = werr
+	}
+	return n, err
+}
+
+// Close closes the writer stream. It ensures that all data from the
+// buffer will be compressed and the LZMA stream will be finished.
+func (w *Writer) Close() error {
+	if w.h.size >= 0 {
+		n := w.e.Compressed() + int64(w.e.dict.Buffered())
+		if n != w.h.size {
+			return errSize
+		}
+	}
+	err := w.e.Close()
+	if w.buf != nil {
+		ferr := w.buf.Flush()
+		if err == nil {
+			err = ferr
+		}
+	}
+	return err
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzma/writer2.go b/vendor/github.com/ulikunitz/xz/lzma/writer2.go
new file mode 100644
index 000000000..7c1afe157
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/writer2.go
@@ -0,0 +1,305 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+import (
+	"bytes"
+	"errors"
+	"io"
+)
+
+// Writer2Config is used to create a Writer2 using parameters.
+type Writer2Config struct {
+	// The properties for the encoding. If the it is nil the value
+	// {LC: 3, LP: 0, PB: 2} will be chosen.
+	Properties *Properties
+	// The capacity of the dictionary. If DictCap is zero, the value
+	// 8 MiB will be chosen.
+	DictCap int
+	// Size of the lookahead buffer; value 0 indicates default size
+	// 4096
+	BufSize int
+	// Match algorithm
+	Matcher MatchAlgorithm
+}
+
+// fill replaces zero values with default values.
+func (c *Writer2Config) fill() {
+	if c.Properties == nil {
+		c.Properties = &Properties{LC: 3, LP: 0, PB: 2}
+	}
+	if c.DictCap == 0 {
+		c.DictCap = 8 * 1024 * 1024
+	}
+	if c.BufSize == 0 {
+		c.BufSize = 4096
+	}
+}
+
+// Verify checks the Writer2Config for correctness. Zero values will be
+// replaced by default values.
+func (c *Writer2Config) Verify() error {
+	c.fill()
+	var err error
+	if c == nil {
+		return errors.New("lzma: WriterConfig is nil")
+	}
+	if c.Properties == nil {
+		return errors.New("lzma: WriterConfig has no Properties set")
+	}
+	if err = c.Properties.verify(); err != nil {
+		return err
+	}
+	if !(MinDictCap <= c.DictCap && int64(c.DictCap) <= MaxDictCap) {
+		return errors.New("lzma: dictionary capacity is out of range")
+	}
+	if !(maxMatchLen <= c.BufSize) {
+		return errors.New("lzma: lookahead buffer size too small")
+	}
+	if c.Properties.LC+c.Properties.LP > 4 {
+		return errors.New("lzma: sum of lc and lp exceeds 4")
+	}
+	if err = c.Matcher.verify(); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Writer2 supports the creation of an LZMA2 stream. But note that
+// written data is buffered, so call Flush or Close to write data to the
+// underlying writer. The Close method writes the end-of-stream marker
+// to the stream. So you may be able to concatenate the output of two
+// writers as long the output of the first writer has only been flushed
+// but not closed.
+//
+// Any change to the fields Properties, DictCap must be done before the
+// first call to Write, Flush or Close.
+type Writer2 struct {
+	w io.Writer
+
+	start   *state
+	encoder *encoder
+
+	cstate chunkState
+	ctype  chunkType
+
+	buf bytes.Buffer
+	lbw LimitedByteWriter
+}
+
+// NewWriter2 creates an LZMA2 chunk sequence writer with the default
+// parameters and options.
+func NewWriter2(lzma2 io.Writer) (w *Writer2, err error) {
+	return Writer2Config{}.NewWriter2(lzma2)
+}
+
+// NewWriter2 creates a new LZMA2 writer using the given configuration.
+func (c Writer2Config) NewWriter2(lzma2 io.Writer) (w *Writer2, err error) {
+	if err = c.Verify(); err != nil {
+		return nil, err
+	}
+	w = &Writer2{
+		w:      lzma2,
+		start:  newState(*c.Properties),
+		cstate: start,
+		ctype:  start.defaultChunkType(),
+	}
+	w.buf.Grow(maxCompressed)
+	w.lbw = LimitedByteWriter{BW: &w.buf, N: maxCompressed}
+	m, err := c.Matcher.new(c.DictCap)
+	if err != nil {
+		return nil, err
+	}
+	d, err := newEncoderDict(c.DictCap, c.BufSize, m)
+	if err != nil {
+		return nil, err
+	}
+	w.encoder, err = newEncoder(&w.lbw, cloneState(w.start), d, 0)
+	if err != nil {
+		return nil, err
+	}
+	return w, nil
+}
+
+// written returns the number of bytes written to the current chunk
+func (w *Writer2) written() int {
+	if w.encoder == nil {
+		return 0
+	}
+	return int(w.encoder.Compressed()) + w.encoder.dict.Buffered()
+}
+
+// errClosed indicates that the writer is closed.
+var errClosed = errors.New("lzma: writer closed")
+
+// Writes data to LZMA2 stream. Note that written data will be buffered.
+// Use Flush or Close to ensure that data is written to the underlying
+// writer.
+func (w *Writer2) Write(p []byte) (n int, err error) {
+	if w.cstate == stop {
+		return 0, errClosed
+	}
+	for n < len(p) {
+		m := maxUncompressed - w.written()
+		if m <= 0 {
+			panic("lzma: maxUncompressed reached")
+		}
+		var q []byte
+		if n+m < len(p) {
+			q = p[n : n+m]
+		} else {
+			q = p[n:]
+		}
+		k, err := w.encoder.Write(q)
+		n += k
+		if err != nil && err != ErrLimit {
+			return n, err
+		}
+		if err == ErrLimit || k == m {
+			if err = w.flushChunk(); err != nil {
+				return n, err
+			}
+		}
+	}
+	return n, nil
+}
+
+// writeUncompressedChunk writes an uncompressed chunk to the LZMA2
+// stream.
+func (w *Writer2) writeUncompressedChunk() error {
+	u := w.encoder.Compressed()
+	if u <= 0 {
+		return errors.New("lzma: can't write empty uncompressed chunk")
+	}
+	if u > maxUncompressed {
+		panic("overrun of uncompressed data limit")
+	}
+	switch w.ctype {
+	case cLRND:
+		w.ctype = cUD
+	default:
+		w.ctype = cU
+	}
+	w.encoder.state = w.start
+
+	header := chunkHeader{
+		ctype:        w.ctype,
+		uncompressed: uint32(u - 1),
+	}
+	hdata, err := header.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	if _, err = w.w.Write(hdata); err != nil {
+		return err
+	}
+	_, err = w.encoder.dict.CopyN(w.w, int(u))
+	return err
+}
+
+// writeCompressedChunk writes a compressed chunk to the underlying
+// writer.
+func (w *Writer2) writeCompressedChunk() error {
+	if w.ctype == cU || w.ctype == cUD {
+		panic("chunk type uncompressed")
+	}
+
+	u := w.encoder.Compressed()
+	if u <= 0 {
+		return errors.New("writeCompressedChunk: empty chunk")
+	}
+	if u > maxUncompressed {
+		panic("overrun of uncompressed data limit")
+	}
+	c := w.buf.Len()
+	if c <= 0 {
+		panic("no compressed data")
+	}
+	if c > maxCompressed {
+		panic("overrun of compressed data limit")
+	}
+	header := chunkHeader{
+		ctype:        w.ctype,
+		uncompressed: uint32(u - 1),
+		compressed:   uint16(c - 1),
+		props:        w.encoder.state.Properties,
+	}
+	hdata, err := header.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	if _, err = w.w.Write(hdata); err != nil {
+		return err
+	}
+	_, err = io.Copy(w.w, &w.buf)
+	return err
+}
+
+// writes a single chunk to the underlying writer.
+func (w *Writer2) writeChunk() error {
+	u := int(uncompressedHeaderLen + w.encoder.Compressed())
+	c := headerLen(w.ctype) + w.buf.Len()
+	if u < c {
+		return w.writeUncompressedChunk()
+	}
+	return w.writeCompressedChunk()
+}
+
+// flushChunk terminates the current chunk. The encoder will be reset
+// to support the next chunk.
+func (w *Writer2) flushChunk() error {
+	if w.written() == 0 {
+		return nil
+	}
+	var err error
+	if err = w.encoder.Close(); err != nil {
+		return err
+	}
+	if err = w.writeChunk(); err != nil {
+		return err
+	}
+	w.buf.Reset()
+	w.lbw.N = maxCompressed
+	if err = w.encoder.Reopen(&w.lbw); err != nil {
+		return err
+	}
+	if err = w.cstate.next(w.ctype); err != nil {
+		return err
+	}
+	w.ctype = w.cstate.defaultChunkType()
+	w.start = cloneState(w.encoder.state)
+	return nil
+}
+
+// Flush writes all buffered data out to the underlying stream. This
+// could result in multiple chunks to be created.
+func (w *Writer2) Flush() error {
+	if w.cstate == stop {
+		return errClosed
+	}
+	for w.written() > 0 {
+		if err := w.flushChunk(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Close terminates the LZMA2 stream with an EOS chunk.
+func (w *Writer2) Close() error {
+	if w.cstate == stop {
+		return errClosed
+	}
+	if err := w.Flush(); err != nil {
+		return nil
+	}
+	// write zero byte EOS chunk
+	_, err := w.w.Write([]byte{0})
+	if err != nil {
+		return err
+	}
+	w.cstate = stop
+	return nil
+}
diff --git a/vendor/github.com/ulikunitz/xz/lzmafilter.go b/vendor/github.com/ulikunitz/xz/lzmafilter.go
new file mode 100644
index 000000000..69cf5f7c2
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzmafilter.go
@@ -0,0 +1,117 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xz
+
+import (
+	"errors"
+	"fmt"
+	"io"
+
+	"github.com/ulikunitz/xz/lzma"
+)
+
+// LZMA filter constants.
+const (
+	lzmaFilterID  = 0x21
+	lzmaFilterLen = 3
+)
+
+// lzmaFilter declares the LZMA2 filter information stored in an xz
+// block header.
+type lzmaFilter struct {
+	dictCap int64
+}
+
+// String returns a representation of the LZMA filter.
+func (f lzmaFilter) String() string {
+	return fmt.Sprintf("LZMA dict cap %#x", f.dictCap)
+}
+
+// id returns the ID for the LZMA2 filter.
+func (f lzmaFilter) id() uint64 { return lzmaFilterID }
+
+// MarshalBinary converts the lzmaFilter in its encoded representation.
+func (f lzmaFilter) MarshalBinary() (data []byte, err error) {
+	c := lzma.EncodeDictCap(f.dictCap)
+	return []byte{lzmaFilterID, 1, c}, nil
+}
+
+// UnmarshalBinary unmarshals the given data representation of the LZMA2
+// filter.
+func (f *lzmaFilter) UnmarshalBinary(data []byte) error {
+	if len(data) != lzmaFilterLen {
+		return errors.New("xz: data for LZMA2 filter has wrong length")
+	}
+	if data[0] != lzmaFilterID {
+		return errors.New("xz: wrong LZMA2 filter id")
+	}
+	if data[1] != 1 {
+		return errors.New("xz: wrong LZMA2 filter size")
+	}
+	dc, err := lzma.DecodeDictCap(data[2])
+	if err != nil {
+		return errors.New("xz: wrong LZMA2 dictionary size property")
+	}
+
+	f.dictCap = dc
+	return nil
+}
+
+// reader creates a new reader for the LZMA2 filter.
+func (f lzmaFilter) reader(r io.Reader, c *ReaderConfig) (fr io.Reader,
+	err error) {
+
+	config := new(lzma.Reader2Config)
+	if c != nil {
+		config.DictCap = c.DictCap
+	}
+	dc := int(f.dictCap)
+	if dc < 1 {
+		return nil, errors.New("xz: LZMA2 filter parameter " +
+			"dictionary capacity overflow")
+	}
+	if dc > config.DictCap {
+		config.DictCap = dc
+	}
+
+	fr, err = config.NewReader2(r)
+	if err != nil {
+		return nil, err
+	}
+	return fr, nil
+}
+
+// writeCloser creates a io.WriteCloser for the LZMA2 filter.
+func (f lzmaFilter) writeCloser(w io.WriteCloser, c *WriterConfig,
+) (fw io.WriteCloser, err error) {
+	config := new(lzma.Writer2Config)
+	if c != nil {
+		*config = lzma.Writer2Config{
+			Properties: c.Properties,
+			DictCap:    c.DictCap,
+			BufSize:    c.BufSize,
+			Matcher:    c.Matcher,
+		}
+	}
+
+	dc := int(f.dictCap)
+	if dc < 1 {
+		return nil, errors.New("xz: LZMA2 filter parameter " +
+			"dictionary capacity overflow")
+	}
+	if dc > config.DictCap {
+		config.DictCap = dc
+	}
+
+	fw, err = config.NewWriter2(w)
+	if err != nil {
+		return nil, err
+	}
+	return fw, nil
+}
+
+// last returns true, because an LZMA2 filter must be the last filter in
+// the filter list.
+func (f lzmaFilter) last() bool { return true }
diff --git a/vendor/github.com/ulikunitz/xz/reader.go b/vendor/github.com/ulikunitz/xz/reader.go
new file mode 100644
index 000000000..0634c6bcc
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/reader.go
@@ -0,0 +1,373 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package xz supports the compression and decompression of xz files. It
+// supports version 1.0.4 of the specification without the non-LZMA2
+// filters. See http://tukaani.org/xz/xz-file-format-1.0.4.txt
+package xz
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"hash"
+	"io"
+
+	"github.com/ulikunitz/xz/internal/xlog"
+	"github.com/ulikunitz/xz/lzma"
+)
+
+// ReaderConfig defines the parameters for the xz reader. The
+// SingleStream parameter requests the reader to assume that the
+// underlying stream contains only a single stream.
+type ReaderConfig struct {
+	DictCap      int
+	SingleStream bool
+}
+
+// fill replaces all zero values with their default values.
+func (c *ReaderConfig) fill() {
+	if c.DictCap == 0 {
+		c.DictCap = 8 * 1024 * 1024
+	}
+}
+
+// Verify checks the reader parameters for Validity. Zero values will be
+// replaced by default values.
+func (c *ReaderConfig) Verify() error {
+	if c == nil {
+		return errors.New("xz: reader parameters are nil")
+	}
+	lc := lzma.Reader2Config{DictCap: c.DictCap}
+	if err := lc.Verify(); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Reader supports the reading of one or multiple xz streams.
+type Reader struct {
+	ReaderConfig
+
+	xz io.Reader
+	sr *streamReader
+}
+
+// streamReader decodes a single xz stream
+type streamReader struct {
+	ReaderConfig
+
+	xz      io.Reader
+	br      *blockReader
+	newHash func() hash.Hash
+	h       header
+	index   []record
+}
+
+// NewReader creates a new xz reader using the default parameters.
+// The function reads and checks the header of the first XZ stream. The
+// reader will process multiple streams including padding.
+func NewReader(xz io.Reader) (r *Reader, err error) {
+	return ReaderConfig{}.NewReader(xz)
+}
+
+// NewReader creates an xz stream reader. The created reader will be
+// able to process multiple streams and padding unless a SingleStream
+// has been set in the reader configuration c.
+func (c ReaderConfig) NewReader(xz io.Reader) (r *Reader, err error) {
+	if err = c.Verify(); err != nil {
+		return nil, err
+	}
+	r = &Reader{
+		ReaderConfig: c,
+		xz:           xz,
+	}
+	if r.sr, err = c.newStreamReader(xz); err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
+		return nil, err
+	}
+	return r, nil
+}
+
+var errUnexpectedData = errors.New("xz: unexpected data after stream")
+
+// Read reads uncompressed data from the stream.
+func (r *Reader) Read(p []byte) (n int, err error) {
+	for n < len(p) {
+		if r.sr == nil {
+			if r.SingleStream {
+				data := make([]byte, 1)
+				_, err = io.ReadFull(r.xz, data)
+				if err != io.EOF {
+					return n, errUnexpectedData
+				}
+				return n, io.EOF
+			}
+			for {
+				r.sr, err = r.ReaderConfig.newStreamReader(r.xz)
+				if err != errPadding {
+					break
+				}
+			}
+			if err != nil {
+				return n, err
+			}
+		}
+		k, err := r.sr.Read(p[n:])
+		n += k
+		if err != nil {
+			if err == io.EOF {
+				r.sr = nil
+				continue
+			}
+			return n, err
+		}
+	}
+	return n, nil
+}
+
+var errPadding = errors.New("xz: padding (4 zero bytes) encountered")
+
+// newStreamReader creates a new xz stream reader using the given configuration
+// parameters. NewReader reads and checks the header of the xz stream.
+func (c ReaderConfig) newStreamReader(xz io.Reader) (r *streamReader, err error) {
+	if err = c.Verify(); err != nil {
+		return nil, err
+	}
+	data := make([]byte, HeaderLen)
+	if _, err := io.ReadFull(xz, data[:4]); err != nil {
+		return nil, err
+	}
+	if bytes.Equal(data[:4], []byte{0, 0, 0, 0}) {
+		return nil, errPadding
+	}
+	if _, err = io.ReadFull(xz, data[4:]); err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
+		return nil, err
+	}
+	r = &streamReader{
+		ReaderConfig: c,
+		xz:           xz,
+		index:        make([]record, 0, 4),
+	}
+	if err = r.h.UnmarshalBinary(data); err != nil {
+		return nil, err
+	}
+	xlog.Debugf("xz header %s", r.h)
+	if r.newHash, err = newHashFunc(r.h.flags); err != nil {
+		return nil, err
+	}
+	return r, nil
+}
+
+// errIndex indicates an error with the xz file index.
+var errIndex = errors.New("xz: error in xz file index")
+
+// readTail reads the index body and the xz footer.
+func (r *streamReader) readTail() error {
+	index, n, err := readIndexBody(r.xz)
+	if err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
+		return err
+	}
+	if len(index) != len(r.index) {
+		return fmt.Errorf("xz: index length is %d; want %d",
+			len(index), len(r.index))
+	}
+	for i, rec := range r.index {
+		if rec != index[i] {
+			return fmt.Errorf("xz: record %d is %v; want %v",
+				i, rec, index[i])
+		}
+	}
+
+	p := make([]byte, footerLen)
+	if _, err = io.ReadFull(r.xz, p); err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
+		return err
+	}
+	var f footer
+	if err = f.UnmarshalBinary(p); err != nil {
+		return err
+	}
+	xlog.Debugf("xz footer %s", f)
+	if f.flags != r.h.flags {
+		return errors.New("xz: footer flags incorrect")
+	}
+	if f.indexSize != int64(n)+1 {
+		return errors.New("xz: index size in footer wrong")
+	}
+	return nil
+}
+
+// Read reads actual data from the xz stream.
+func (r *streamReader) Read(p []byte) (n int, err error) {
+	for n < len(p) {
+		if r.br == nil {
+			bh, hlen, err := readBlockHeader(r.xz)
+			if err != nil {
+				if err == errIndexIndicator {
+					if err = r.readTail(); err != nil {
+						return n, err
+					}
+					return n, io.EOF
+				}
+				return n, err
+			}
+			xlog.Debugf("block %v", *bh)
+			r.br, err = r.ReaderConfig.newBlockReader(r.xz, bh,
+				hlen, r.newHash())
+			if err != nil {
+				return n, err
+			}
+		}
+		k, err := r.br.Read(p[n:])
+		n += k
+		if err != nil {
+			if err == io.EOF {
+				r.index = append(r.index, r.br.record())
+				r.br = nil
+			} else {
+				return n, err
+			}
+		}
+	}
+	return n, nil
+}
+
+// countingReader is a reader that counts the bytes read.
+type countingReader struct {
+	r io.Reader
+	n int64
+}
+
+// Read reads data from the wrapped reader and adds it to the n field.
+func (lr *countingReader) Read(p []byte) (n int, err error) {
+	n, err = lr.r.Read(p)
+	lr.n += int64(n)
+	return n, err
+}
+
+// blockReader supports the reading of a block.
+type blockReader struct {
+	lxz       countingReader
+	header    *blockHeader
+	headerLen int
+	n         int64
+	hash      hash.Hash
+	r         io.Reader
+	err       error
+}
+
+// newBlockReader creates a new block reader.
+func (c *ReaderConfig) newBlockReader(xz io.Reader, h *blockHeader,
+	hlen int, hash hash.Hash) (br *blockReader, err error) {
+
+	br = &blockReader{
+		lxz:       countingReader{r: xz},
+		header:    h,
+		headerLen: hlen,
+		hash:      hash,
+	}
+
+	fr, err := c.newFilterReader(&br.lxz, h.filters)
+	if err != nil {
+		return nil, err
+	}
+	br.r = io.TeeReader(fr, br.hash)
+
+	return br, nil
+}
+
+// uncompressedSize returns the uncompressed size of the block.
+func (br *blockReader) uncompressedSize() int64 {
+	return br.n
+}
+
+// compressedSize returns the compressed size of the block.
+func (br *blockReader) compressedSize() int64 {
+	return br.lxz.n
+}
+
+// unpaddedSize computes the unpadded size for the block.
+func (br *blockReader) unpaddedSize() int64 {
+	n := int64(br.headerLen)
+	n += br.compressedSize()
+	n += int64(br.hash.Size())
+	return n
+}
+
+// record returns the index record for the current block.
+func (br *blockReader) record() record {
+	return record{br.unpaddedSize(), br.uncompressedSize()}
+}
+
+// errBlockSize indicates that the size of the block in the block header
+// is wrong.
+var errBlockSize = errors.New("xz: wrong uncompressed size for block")
+
+// Read reads data from the block.
+func (br *blockReader) Read(p []byte) (n int, err error) {
+	n, err = br.r.Read(p)
+	br.n += int64(n)
+
+	u := br.header.uncompressedSize
+	if u >= 0 && br.uncompressedSize() > u {
+		return n, errors.New("xz: wrong uncompressed size for block")
+	}
+	c := br.header.compressedSize
+	if c >= 0 && br.compressedSize() > c {
+		return n, errors.New("xz: wrong compressed size for block")
+	}
+	if err != io.EOF {
+		return n, err
+	}
+	if br.uncompressedSize() < u || br.compressedSize() < c {
+		return n, io.ErrUnexpectedEOF
+	}
+
+	s := br.hash.Size()
+	k := padLen(br.lxz.n)
+	q := make([]byte, k+s, k+2*s)
+	if _, err = io.ReadFull(br.lxz.r, q); err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
+		return n, err
+	}
+	if !allZeros(q[:k]) {
+		return n, errors.New("xz: non-zero block padding")
+	}
+	checkSum := q[k:]
+	computedSum := br.hash.Sum(checkSum[s:])
+	if !bytes.Equal(checkSum, computedSum) {
+		return n, errors.New("xz: checksum error for block")
+	}
+	return n, io.EOF
+}
+
+func (c *ReaderConfig) newFilterReader(r io.Reader, f []filter) (fr io.Reader,
+	err error) {
+
+	if err = verifyFilters(f); err != nil {
+		return nil, err
+	}
+
+	fr = r
+	for i := len(f) - 1; i >= 0; i-- {
+		fr, err = f[i].reader(fr, c)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return fr, nil
+}
diff --git a/vendor/github.com/ulikunitz/xz/writer.go b/vendor/github.com/ulikunitz/xz/writer.go
new file mode 100644
index 000000000..c126f7099
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/writer.go
@@ -0,0 +1,386 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xz
+
+import (
+	"errors"
+	"hash"
+	"io"
+
+	"github.com/ulikunitz/xz/lzma"
+)
+
+// WriterConfig describe the parameters for an xz writer.
+type WriterConfig struct {
+	Properties *lzma.Properties
+	DictCap    int
+	BufSize    int
+	BlockSize  int64
+	// checksum method: CRC32, CRC64 or SHA256
+	CheckSum byte
+	// match algorithm
+	Matcher lzma.MatchAlgorithm
+}
+
+// fill replaces zero values with default values.
+func (c *WriterConfig) fill() {
+	if c.Properties == nil {
+		c.Properties = &lzma.Properties{LC: 3, LP: 0, PB: 2}
+	}
+	if c.DictCap == 0 {
+		c.DictCap = 8 * 1024 * 1024
+	}
+	if c.BufSize == 0 {
+		c.BufSize = 4096
+	}
+	if c.BlockSize == 0 {
+		c.BlockSize = maxInt64
+	}
+	if c.CheckSum == 0 {
+		c.CheckSum = CRC64
+	}
+}
+
+// Verify checks the configuration for errors. Zero values will be
+// replaced by default values.
+func (c *WriterConfig) Verify() error {
+	if c == nil {
+		return errors.New("xz: writer configuration is nil")
+	}
+	c.fill()
+	lc := lzma.Writer2Config{
+		Properties: c.Properties,
+		DictCap:    c.DictCap,
+		BufSize:    c.BufSize,
+		Matcher:    c.Matcher,
+	}
+	if err := lc.Verify(); err != nil {
+		return err
+	}
+	if c.BlockSize <= 0 {
+		return errors.New("xz: block size out of range")
+	}
+	if err := verifyFlags(c.CheckSum); err != nil {
+		return err
+	}
+	return nil
+}
+
+// filters creates the filter list for the given parameters.
+func (c *WriterConfig) filters() []filter {
+	return []filter{&lzmaFilter{int64(c.DictCap)}}
+}
+
+// maxInt64 defines the maximum 64-bit signed integer.
+const maxInt64 = 1<<63 - 1
+
+// verifyFilters checks the filter list for the length and the right
+// sequence of filters.
+func verifyFilters(f []filter) error {
+	if len(f) == 0 {
+		return errors.New("xz: no filters")
+	}
+	if len(f) > 4 {
+		return errors.New("xz: more than four filters")
+	}
+	for _, g := range f[:len(f)-1] {
+		if g.last() {
+			return errors.New("xz: last filter is not last")
+		}
+	}
+	if !f[len(f)-1].last() {
+		return errors.New("xz: wrong last filter")
+	}
+	return nil
+}
+
+// newFilterWriteCloser converts a filter list into a WriteCloser that
+// can be used by a blockWriter.
+func (c *WriterConfig) newFilterWriteCloser(w io.Writer, f []filter) (fw io.WriteCloser, err error) {
+	if err = verifyFilters(f); err != nil {
+		return nil, err
+	}
+	fw = nopWriteCloser(w)
+	for i := len(f) - 1; i >= 0; i-- {
+		fw, err = f[i].writeCloser(fw, c)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return fw, nil
+}
+
+// nopWCloser implements a WriteCloser with a Close method not doing
+// anything.
+type nopWCloser struct {
+	io.Writer
+}
+
+// Close returns nil and doesn't do anything else.
+func (c nopWCloser) Close() error {
+	return nil
+}
+
+// nopWriteCloser converts the Writer into a WriteCloser with a Close
+// function that does nothing beside returning nil.
+func nopWriteCloser(w io.Writer) io.WriteCloser {
+	return nopWCloser{w}
+}
+
+// Writer compresses data written to it. It is an io.WriteCloser.
+type Writer struct {
+	WriterConfig
+
+	xz      io.Writer
+	bw      *blockWriter
+	newHash func() hash.Hash
+	h       header
+	index   []record
+	closed  bool
+}
+
+// newBlockWriter creates a new block writer writes the header out.
+func (w *Writer) newBlockWriter() error {
+	var err error
+	w.bw, err = w.WriterConfig.newBlockWriter(w.xz, w.newHash())
+	if err != nil {
+		return err
+	}
+	if err = w.bw.writeHeader(w.xz); err != nil {
+		return err
+	}
+	return nil
+}
+
+// closeBlockWriter closes a block writer and records the sizes in the
+// index.
+func (w *Writer) closeBlockWriter() error {
+	var err error
+	if err = w.bw.Close(); err != nil {
+		return err
+	}
+	w.index = append(w.index, w.bw.record())
+	return nil
+}
+
+// NewWriter creates a new xz writer using default parameters.
+func NewWriter(xz io.Writer) (w *Writer, err error) {
+	return WriterConfig{}.NewWriter(xz)
+}
+
+// NewWriter creates a new Writer using the given configuration parameters.
+func (c WriterConfig) NewWriter(xz io.Writer) (w *Writer, err error) {
+	if err = c.Verify(); err != nil {
+		return nil, err
+	}
+	w = &Writer{
+		WriterConfig: c,
+		xz:           xz,
+		h:            header{c.CheckSum},
+		index:        make([]record, 0, 4),
+	}
+	if w.newHash, err = newHashFunc(c.CheckSum); err != nil {
+		return nil, err
+	}
+	data, err := w.h.MarshalBinary()
+	if _, err = xz.Write(data); err != nil {
+		return nil, err
+	}
+	if err = w.newBlockWriter(); err != nil {
+		return nil, err
+	}
+	return w, nil
+
+}
+
+// Write compresses the uncompressed data provided.
+func (w *Writer) Write(p []byte) (n int, err error) {
+	if w.closed {
+		return 0, errClosed
+	}
+	for {
+		k, err := w.bw.Write(p[n:])
+		n += k
+		if err != errNoSpace {
+			return n, err
+		}
+		if err = w.closeBlockWriter(); err != nil {
+			return n, err
+		}
+		if err = w.newBlockWriter(); err != nil {
+			return n, err
+		}
+	}
+}
+
+// Close closes the writer and adds the footer to the Writer. Close
+// doesn't close the underlying writer.
+func (w *Writer) Close() error {
+	if w.closed {
+		return errClosed
+	}
+	w.closed = true
+	var err error
+	if err = w.closeBlockWriter(); err != nil {
+		return err
+	}
+
+	f := footer{flags: w.h.flags}
+	if f.indexSize, err = writeIndex(w.xz, w.index); err != nil {
+		return err
+	}
+	data, err := f.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	if _, err = w.xz.Write(data); err != nil {
+		return err
+	}
+	return nil
+}
+
+// countingWriter is a writer that counts all data written to it.
+type countingWriter struct {
+	w io.Writer
+	n int64
+}
+
+// Write writes data to the countingWriter.
+func (cw *countingWriter) Write(p []byte) (n int, err error) {
+	n, err = cw.w.Write(p)
+	cw.n += int64(n)
+	if err == nil && cw.n < 0 {
+		return n, errors.New("xz: counter overflow")
+	}
+	return
+}
+
+// blockWriter is writes a single block.
+type blockWriter struct {
+	cxz countingWriter
+	// mw combines io.WriteCloser w and the hash.
+	mw        io.Writer
+	w         io.WriteCloser
+	n         int64
+	blockSize int64
+	closed    bool
+	headerLen int
+
+	filters []filter
+	hash    hash.Hash
+}
+
+// newBlockWriter creates a new block writer.
+func (c *WriterConfig) newBlockWriter(xz io.Writer, hash hash.Hash) (bw *blockWriter, err error) {
+	bw = &blockWriter{
+		cxz:       countingWriter{w: xz},
+		blockSize: c.BlockSize,
+		filters:   c.filters(),
+		hash:      hash,
+	}
+	bw.w, err = c.newFilterWriteCloser(&bw.cxz, bw.filters)
+	if err != nil {
+		return nil, err
+	}
+	bw.mw = io.MultiWriter(bw.w, bw.hash)
+	return bw, nil
+}
+
+// writeHeader writes the header. If the function is called after Close
+// the commpressedSize and uncompressedSize fields will be filled.
+func (bw *blockWriter) writeHeader(w io.Writer) error {
+	h := blockHeader{
+		compressedSize:   -1,
+		uncompressedSize: -1,
+		filters:          bw.filters,
+	}
+	if bw.closed {
+		h.compressedSize = bw.compressedSize()
+		h.uncompressedSize = bw.uncompressedSize()
+	}
+	data, err := h.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	if _, err = w.Write(data); err != nil {
+		return err
+	}
+	bw.headerLen = len(data)
+	return nil
+}
+
+// compressed size returns the amount of data written to the underlying
+// stream.
+func (bw *blockWriter) compressedSize() int64 {
+	return bw.cxz.n
+}
+
+// uncompressedSize returns the number of data written to the
+// blockWriter
+func (bw *blockWriter) uncompressedSize() int64 {
+	return bw.n
+}
+
+// unpaddedSize returns the sum of the header length, the uncompressed
+// size of the block and the hash size.
+func (bw *blockWriter) unpaddedSize() int64 {
+	if bw.headerLen <= 0 {
+		panic("xz: block header not written")
+	}
+	n := int64(bw.headerLen)
+	n += bw.compressedSize()
+	n += int64(bw.hash.Size())
+	return n
+}
+
+// record returns the record for the current stream. Call Close before
+// calling this method.
+func (bw *blockWriter) record() record {
+	return record{bw.unpaddedSize(), bw.uncompressedSize()}
+}
+
+var errClosed = errors.New("xz: writer already closed")
+
+var errNoSpace = errors.New("xz: no space")
+
+// Write writes uncompressed data to the block writer.
+func (bw *blockWriter) Write(p []byte) (n int, err error) {
+	if bw.closed {
+		return 0, errClosed
+	}
+
+	t := bw.blockSize - bw.n
+	if int64(len(p)) > t {
+		err = errNoSpace
+		p = p[:t]
+	}
+
+	var werr error
+	n, werr = bw.mw.Write(p)
+	bw.n += int64(n)
+	if werr != nil {
+		return n, werr
+	}
+	return n, err
+}
+
+// Close closes the writer.
+func (bw *blockWriter) Close() error {
+	if bw.closed {
+		return errClosed
+	}
+	bw.closed = true
+	if err := bw.w.Close(); err != nil {
+		return err
+	}
+	s := bw.hash.Size()
+	k := padLen(bw.cxz.n)
+	p := make([]byte, k+s)
+	bw.hash.Sum(p[k:k])
+	if _, err := bw.cxz.w.Write(p); err != nil {
+		return err
+	}
+	return nil
+}