1 files changed, 728 insertions, 0 deletions
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
+}