Move deps from _workspace/ to vendor/

godep restore
pushd $GOPATH/src/github.com/appc/spec
git co master
popd
go get go4.org/errorutil
rm -rf Godeps
godep save ./...
git add vendor
git add -f $(git ls-files --other vendor/)
git co -- Godeps/LICENSES Godeps/.license_file_state Godeps/OWNERS

vendor/github.com/Microsoft/go-winio/LICENSE

@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Microsoft
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+

vendor/github.com/Microsoft/go-winio/README.md

@@ -0,0 +1,15 @@
+# go-winio
+
+This repository contains utilities for efficiently performing Win32 IO operations in 
+Go. Currently, this is focused on accessing named pipes and other file handles, and
+for using named pipes as a net transport.
+
+This code relies on IO completion ports to avoid blocking IO on system threads, allowing Go 
+to reuse the thread to schedule another goroutine. This limits support to Windows Vista and 
+newer operating systems. This is similar to the implementation of network sockets in Go's net
+package.
+
+Please see the LICENSE file for licensing information.
+
+Thanks to natefinch for the inspiration for this library. See https://github.com/natefinch/npipe 
+for another named pipe implementation.

vendor/github.com/Microsoft/go-winio/archive/tar/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2012 The Go Authors. 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.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER 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.

vendor/github.com/Microsoft/go-winio/archive/tar/common.go

@@ -0,0 +1,342 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package tar implements access to tar archives.
+// It aims to cover most of the variations, including those produced
+// by GNU and BSD tars.
+//
+// References:
+//   http://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5
+//   http://www.gnu.org/software/tar/manual/html_node/Standard.html
+//   http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html
+package tar
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"path"
+	"time"
+)
+
+const (
+	blockSize = 512
+
+	// Types
+	TypeReg           = '0'    // regular file
+	TypeRegA          = '\x00' // regular file
+	TypeLink          = '1'    // hard link
+	TypeSymlink       = '2'    // symbolic link
+	TypeChar          = '3'    // character device node
+	TypeBlock         = '4'    // block device node
+	TypeDir           = '5'    // directory
+	TypeFifo          = '6'    // fifo node
+	TypeCont          = '7'    // reserved
+	TypeXHeader       = 'x'    // extended header
+	TypeXGlobalHeader = 'g'    // global extended header
+	TypeGNULongName   = 'L'    // Next file has a long name
+	TypeGNULongLink   = 'K'    // Next file symlinks to a file w/ a long name
+	TypeGNUSparse     = 'S'    // sparse file
+)
+
+// A Header represents a single header in a tar archive.
+// Some fields may not be populated.
+type Header struct {
+	Name       string    // name of header file entry
+	Mode       int64     // permission and mode bits
+	Uid        int       // user id of owner
+	Gid        int       // group id of owner
+	Size       int64     // length in bytes
+	ModTime    time.Time // modified time
+	Typeflag   byte      // type of header entry
+	Linkname   string    // target name of link
+	Uname      string    // user name of owner
+	Gname      string    // group name of owner
+	Devmajor   int64     // major number of character or block device
+	Devminor   int64     // minor number of character or block device
+	AccessTime time.Time // access time
+	ChangeTime time.Time // status change time
+	Xattrs     map[string]string
+	Winheaders map[string]string
+}
+
+// File name constants from the tar spec.
+const (
+	fileNameSize       = 100 // Maximum number of bytes in a standard tar name.
+	fileNamePrefixSize = 155 // Maximum number of ustar extension bytes.
+)
+
+// FileInfo returns an os.FileInfo for the Header.
+func (h *Header) FileInfo() os.FileInfo {
+	return headerFileInfo{h}
+}
+
+// headerFileInfo implements os.FileInfo.
+type headerFileInfo struct {
+	h *Header
+}
+
+func (fi headerFileInfo) Size() int64        { return fi.h.Size }
+func (fi headerFileInfo) IsDir() bool        { return fi.Mode().IsDir() }
+func (fi headerFileInfo) ModTime() time.Time { return fi.h.ModTime }
+func (fi headerFileInfo) Sys() interface{}   { return fi.h }
+
+// Name returns the base name of the file.
+func (fi headerFileInfo) Name() string {
+	if fi.IsDir() {
+		return path.Base(path.Clean(fi.h.Name))
+	}
+	return path.Base(fi.h.Name)
+}
+
+// Mode returns the permission and mode bits for the headerFileInfo.
+func (fi headerFileInfo) Mode() (mode os.FileMode) {
+	// Set file permission bits.
+	mode = os.FileMode(fi.h.Mode).Perm()
+
+	// Set setuid, setgid and sticky bits.
+	if fi.h.Mode&c_ISUID != 0 {
+		// setuid
+		mode |= os.ModeSetuid
+	}
+	if fi.h.Mode&c_ISGID != 0 {
+		// setgid
+		mode |= os.ModeSetgid
+	}
+	if fi.h.Mode&c_ISVTX != 0 {
+		// sticky
+		mode |= os.ModeSticky
+	}
+
+	// Set file mode bits.
+	// clear perm, setuid, setgid and sticky bits.
+	m := os.FileMode(fi.h.Mode) &^ 07777
+	if m == c_ISDIR {
+		// directory
+		mode |= os.ModeDir
+	}
+	if m == c_ISFIFO {
+		// named pipe (FIFO)
+		mode |= os.ModeNamedPipe
+	}
+	if m == c_ISLNK {
+		// symbolic link
+		mode |= os.ModeSymlink
+	}
+	if m == c_ISBLK {
+		// device file
+		mode |= os.ModeDevice
+	}
+	if m == c_ISCHR {
+		// Unix character device
+		mode |= os.ModeDevice
+		mode |= os.ModeCharDevice
+	}
+	if m == c_ISSOCK {
+		// Unix domain socket
+		mode |= os.ModeSocket
+	}
+
+	switch fi.h.Typeflag {
+	case TypeSymlink:
+		// symbolic link
+		mode |= os.ModeSymlink
+	case TypeChar:
+		// character device node
+		mode |= os.ModeDevice
+		mode |= os.ModeCharDevice
+	case TypeBlock:
+		// block device node
+		mode |= os.ModeDevice
+	case TypeDir:
+		// directory
+		mode |= os.ModeDir
+	case TypeFifo:
+		// fifo node
+		mode |= os.ModeNamedPipe
+	}
+
+	return mode
+}
+
+// sysStat, if non-nil, populates h from system-dependent fields of fi.
+var sysStat func(fi os.FileInfo, h *Header) error
+
+// Mode constants from the tar spec.
+const (
+	c_ISUID  = 04000   // Set uid
+	c_ISGID  = 02000   // Set gid
+	c_ISVTX  = 01000   // Save text (sticky bit)
+	c_ISDIR  = 040000  // Directory
+	c_ISFIFO = 010000  // FIFO
+	c_ISREG  = 0100000 // Regular file
+	c_ISLNK  = 0120000 // Symbolic link
+	c_ISBLK  = 060000  // Block special file
+	c_ISCHR  = 020000  // Character special file
+	c_ISSOCK = 0140000 // Socket
+)
+
+// Keywords for the PAX Extended Header
+const (
+	paxAtime    = "atime"
+	paxCharset  = "charset"
+	paxComment  = "comment"
+	paxCtime    = "ctime" // please note that ctime is not a valid pax header.
+	paxGid      = "gid"
+	paxGname    = "gname"
+	paxLinkpath = "linkpath"
+	paxMtime    = "mtime"
+	paxPath     = "path"
+	paxSize     = "size"
+	paxUid      = "uid"
+	paxUname    = "uname"
+	paxXattr    = "SCHILY.xattr."
+	paxWindows  = "MSWINDOWS."
+	paxNone     = ""
+)
+
+// FileInfoHeader creates a partially-populated Header from fi.
+// If fi describes a symlink, FileInfoHeader records link as the link target.
+// If fi describes a directory, a slash is appended to the name.
+// Because os.FileInfo's Name method returns only the base name of
+// the file it describes, it may be necessary to modify the Name field
+// of the returned header to provide the full path name of the file.
+func FileInfoHeader(fi os.FileInfo, link string) (*Header, error) {
+	if fi == nil {
+		return nil, errors.New("tar: FileInfo is nil")
+	}
+	fm := fi.Mode()
+	h := &Header{
+		Name:    fi.Name(),
+		ModTime: fi.ModTime(),
+		Mode:    int64(fm.Perm()), // or'd with c_IS* constants later
+	}
+	switch {
+	case fm.IsRegular():
+		h.Mode |= c_ISREG
+		h.Typeflag = TypeReg
+		h.Size = fi.Size()
+	case fi.IsDir():
+		h.Typeflag = TypeDir
+		h.Mode |= c_ISDIR
+		h.Name += "/"
+	case fm&os.ModeSymlink != 0:
+		h.Typeflag = TypeSymlink
+		h.Mode |= c_ISLNK
+		h.Linkname = link
+	case fm&os.ModeDevice != 0:
+		if fm&os.ModeCharDevice != 0 {
+			h.Mode |= c_ISCHR
+			h.Typeflag = TypeChar
+		} else {
+			h.Mode |= c_ISBLK
+			h.Typeflag = TypeBlock
+		}
+	case fm&os.ModeNamedPipe != 0:
+		h.Typeflag = TypeFifo
+		h.Mode |= c_ISFIFO
+	case fm&os.ModeSocket != 0:
+		h.Mode |= c_ISSOCK
+	default:
+		return nil, fmt.Errorf("archive/tar: unknown file mode %v", fm)
+	}
+	if fm&os.ModeSetuid != 0 {
+		h.Mode |= c_ISUID
+	}
+	if fm&os.ModeSetgid != 0 {
+		h.Mode |= c_ISGID
+	}
+	if fm&os.ModeSticky != 0 {
+		h.Mode |= c_ISVTX
+	}
+	// If possible, populate additional fields from OS-specific
+	// FileInfo fields.
+	if sys, ok := fi.Sys().(*Header); ok {
+		// This FileInfo came from a Header (not the OS). Use the
+		// original Header to populate all remaining fields.
+		h.Uid = sys.Uid
+		h.Gid = sys.Gid
+		h.Uname = sys.Uname
+		h.Gname = sys.Gname
+		h.AccessTime = sys.AccessTime
+		h.ChangeTime = sys.ChangeTime
+		if sys.Xattrs != nil {
+			h.Xattrs = make(map[string]string)
+			for k, v := range sys.Xattrs {
+				h.Xattrs[k] = v
+			}
+		}
+		if sys.Typeflag == TypeLink {
+			// hard link
+			h.Typeflag = TypeLink
+			h.Size = 0
+			h.Linkname = sys.Linkname
+		}
+	}
+	if sysStat != nil {
+		return h, sysStat(fi, h)
+	}
+	return h, nil
+}
+
+var zeroBlock = make([]byte, blockSize)
+
+// POSIX specifies a sum of the unsigned byte values, but the Sun tar uses signed byte values.
+// We compute and return both.
+func checksum(header []byte) (unsigned int64, signed int64) {
+	for i := 0; i < len(header); i++ {
+		if i == 148 {
+			// The chksum field (header[148:156]) is special: it should be treated as space bytes.
+			unsigned += ' ' * 8
+			signed += ' ' * 8
+			i += 7
+			continue
+		}
+		unsigned += int64(header[i])
+		signed += int64(int8(header[i]))
+	}
+	return
+}
+
+type slicer []byte
+
+func (sp *slicer) next(n int) (b []byte) {
+	s := *sp
+	b, *sp = s[0:n], s[n:]
+	return
+}
+
+func isASCII(s string) bool {
+	for _, c := range s {
+		if c >= 0x80 {
+			return false
+		}
+	}
+	return true
+}
+
+func toASCII(s string) string {
+	if isASCII(s) {
+		return s
+	}
+	var buf bytes.Buffer
+	for _, c := range s {
+		if c < 0x80 {
+			buf.WriteByte(byte(c))
+		}
+	}
+	return buf.String()
+}
+
+// isHeaderOnlyType checks if the given type flag is of the type that has no
+// data section even if a size is specified.
+func isHeaderOnlyType(flag byte) bool {
+	switch flag {
+	case TypeLink, TypeSymlink, TypeChar, TypeBlock, TypeDir, TypeFifo:
+		return true
+	default:
+		return false
+	}
+}

vendor/github.com/Microsoft/go-winio/archive/tar/reader.go

@@ -0,0 +1,996 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tar
+
+// TODO(dsymonds):
+//   - pax extensions
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"io/ioutil"
+	"math"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var (
+	ErrHeader = errors.New("archive/tar: invalid tar header")
+)
+
+const maxNanoSecondIntSize = 9
+
+// A Reader provides sequential access to the contents of a tar archive.
+// A tar archive consists of a sequence of files.
+// The Next method advances to the next file in the archive (including the first),
+// and then it can be treated as an io.Reader to access the file's data.
+type Reader struct {
+	r       io.Reader
+	err     error
+	pad     int64           // amount of padding (ignored) after current file entry
+	curr    numBytesReader  // reader for current file entry
+	hdrBuff [blockSize]byte // buffer to use in readHeader
+}
+
+type parser struct {
+	err error // Last error seen
+}
+
+// A numBytesReader is an io.Reader with a numBytes method, returning the number
+// of bytes remaining in the underlying encoded data.
+type numBytesReader interface {
+	io.Reader
+	numBytes() int64
+}
+
+// A regFileReader is a numBytesReader for reading file data from a tar archive.
+type regFileReader struct {
+	r  io.Reader // underlying reader
+	nb int64     // number of unread bytes for current file entry
+}
+
+// A sparseFileReader is a numBytesReader for reading sparse file data from a
+// tar archive.
+type sparseFileReader struct {
+	rfr   numBytesReader // Reads the sparse-encoded file data
+	sp    []sparseEntry  // The sparse map for the file
+	pos   int64          // Keeps track of file position
+	total int64          // Total size of the file
+}
+
+// A sparseEntry holds a single entry in a sparse file's sparse map.
+//
+// Sparse files are represented using a series of sparseEntrys.
+// Despite the name, a sparseEntry represents an actual data fragment that
+// references data found in the underlying archive stream. All regions not
+// covered by a sparseEntry are logically filled with zeros.
+//
+// For example, if the underlying raw file contains the 10-byte data:
+//	var compactData = "abcdefgh"
+//
+// And the sparse map has the following entries:
+//	var sp = []sparseEntry{
+//		{offset: 2,  numBytes: 5} // Data fragment for [2..7]
+//		{offset: 18, numBytes: 3} // Data fragment for [18..21]
+//	}
+//
+// Then the content of the resulting sparse file with a "real" size of 25 is:
+//	var sparseData = "\x00"*2 + "abcde" + "\x00"*11 + "fgh" + "\x00"*4
+type sparseEntry struct {
+	offset   int64 // Starting position of the fragment
+	numBytes int64 // Length of the fragment
+}
+
+// Keywords for GNU sparse files in a PAX extended header
+const (
+	paxGNUSparseNumBlocks = "GNU.sparse.numblocks"
+	paxGNUSparseOffset    = "GNU.sparse.offset"
+	paxGNUSparseNumBytes  = "GNU.sparse.numbytes"
+	paxGNUSparseMap       = "GNU.sparse.map"
+	paxGNUSparseName      = "GNU.sparse.name"
+	paxGNUSparseMajor     = "GNU.sparse.major"
+	paxGNUSparseMinor     = "GNU.sparse.minor"
+	paxGNUSparseSize      = "GNU.sparse.size"
+	paxGNUSparseRealSize  = "GNU.sparse.realsize"
+)
+
+// Keywords for old GNU sparse headers
+const (
+	oldGNUSparseMainHeaderOffset               = 386
+	oldGNUSparseMainHeaderIsExtendedOffset     = 482
+	oldGNUSparseMainHeaderNumEntries           = 4
+	oldGNUSparseExtendedHeaderIsExtendedOffset = 504
+	oldGNUSparseExtendedHeaderNumEntries       = 21
+	oldGNUSparseOffsetSize                     = 12
+	oldGNUSparseNumBytesSize                   = 12
+)
+
+// NewReader creates a new Reader reading from r.
+func NewReader(r io.Reader) *Reader { return &Reader{r: r} }
+
+// Next advances to the next entry in the tar archive.
+//
+// io.EOF is returned at the end of the input.
+func (tr *Reader) Next() (*Header, error) {
+	if tr.err != nil {
+		return nil, tr.err
+	}
+
+	var hdr *Header
+	var extHdrs map[string]string
+
+	// Externally, Next iterates through the tar archive as if it is a series of
+	// files. Internally, the tar format often uses fake "files" to add meta
+	// data that describes the next file. These meta data "files" should not
+	// normally be visible to the outside. As such, this loop iterates through
+	// one or more "header files" until it finds a "normal file".
+loop:
+	for {
+		tr.err = tr.skipUnread()
+		if tr.err != nil {
+			return nil, tr.err
+		}
+
+		hdr = tr.readHeader()
+		if tr.err != nil {
+			return nil, tr.err
+		}
+
+		// Check for PAX/GNU special headers and files.
+		switch hdr.Typeflag {
+		case TypeXHeader:
+			extHdrs, tr.err = parsePAX(tr)
+			if tr.err != nil {
+				return nil, tr.err
+			}
+			continue loop // This is a meta header affecting the next header
+		case TypeGNULongName, TypeGNULongLink:
+			var realname []byte
+			realname, tr.err = ioutil.ReadAll(tr)
+			if tr.err != nil {
+				return nil, tr.err
+			}
+
+			// Convert GNU extensions to use PAX headers.
+			if extHdrs == nil {
+				extHdrs = make(map[string]string)
+			}
+			var p parser
+			switch hdr.Typeflag {
+			case TypeGNULongName:
+				extHdrs[paxPath] = p.parseString(realname)
+			case TypeGNULongLink:
+				extHdrs[paxLinkpath] = p.parseString(realname)
+			}
+			if p.err != nil {
+				tr.err = p.err
+				return nil, tr.err
+			}
+			continue loop // This is a meta header affecting the next header
+		default:
+			mergePAX(hdr, extHdrs)
+
+			// Check for a PAX format sparse file
+			sp, err := tr.checkForGNUSparsePAXHeaders(hdr, extHdrs)
+			if err != nil {
+				tr.err = err
+				return nil, err
+			}
+			if sp != nil {
+				// Current file is a PAX format GNU sparse file.
+				// Set the current file reader to a sparse file reader.
+				tr.curr, tr.err = newSparseFileReader(tr.curr, sp, hdr.Size)
+				if tr.err != nil {
+					return nil, tr.err
+				}
+			}
+			break loop // This is a file, so stop
+		}
+	}
+	return hdr, nil
+}
+
+// checkForGNUSparsePAXHeaders checks the PAX headers for GNU sparse headers. If they are found, then
+// this function reads the sparse map and returns it. Unknown sparse formats are ignored, causing the file to
+// be treated as a regular file.
+func (tr *Reader) checkForGNUSparsePAXHeaders(hdr *Header, headers map[string]string) ([]sparseEntry, error) {
+	var sparseFormat string
+
+	// Check for sparse format indicators
+	major, majorOk := headers[paxGNUSparseMajor]
+	minor, minorOk := headers[paxGNUSparseMinor]
+	sparseName, sparseNameOk := headers[paxGNUSparseName]
+	_, sparseMapOk := headers[paxGNUSparseMap]
+	sparseSize, sparseSizeOk := headers[paxGNUSparseSize]
+	sparseRealSize, sparseRealSizeOk := headers[paxGNUSparseRealSize]
+
+	// Identify which, if any, sparse format applies from which PAX headers are set
+	if majorOk && minorOk {
+		sparseFormat = major + "." + minor
+	} else if sparseNameOk && sparseMapOk {
+		sparseFormat = "0.1"
+	} else if sparseSizeOk {
+		sparseFormat = "0.0"
+	} else {
+		// Not a PAX format GNU sparse file.
+		return nil, nil
+	}
+
+	// Check for unknown sparse format
+	if sparseFormat != "0.0" && sparseFormat != "0.1" && sparseFormat != "1.0" {
+		return nil, nil
+	}
+
+	// Update hdr from GNU sparse PAX headers
+	if sparseNameOk {
+		hdr.Name = sparseName
+	}
+	if sparseSizeOk {
+		realSize, err := strconv.ParseInt(sparseSize, 10, 0)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		hdr.Size = realSize
+	} else if sparseRealSizeOk {
+		realSize, err := strconv.ParseInt(sparseRealSize, 10, 0)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		hdr.Size = realSize
+	}
+
+	// Set up the sparse map, according to the particular sparse format in use
+	var sp []sparseEntry
+	var err error
+	switch sparseFormat {
+	case "0.0", "0.1":
+		sp, err = readGNUSparseMap0x1(headers)
+	case "1.0":
+		sp, err = readGNUSparseMap1x0(tr.curr)
+	}
+	return sp, err
+}
+
+// mergePAX merges well known headers according to PAX standard.
+// In general headers with the same name as those found
+// in the header struct overwrite those found in the header
+// struct with higher precision or longer values. Esp. useful
+// for name and linkname fields.
+func mergePAX(hdr *Header, headers map[string]string) error {
+	for k, v := range headers {
+		switch k {
+		case paxPath:
+			hdr.Name = v
+		case paxLinkpath:
+			hdr.Linkname = v
+		case paxGname:
+			hdr.Gname = v
+		case paxUname:
+			hdr.Uname = v
+		case paxUid:
+			uid, err := strconv.ParseInt(v, 10, 0)
+			if err != nil {
+				return err
+			}
+			hdr.Uid = int(uid)
+		case paxGid:
+			gid, err := strconv.ParseInt(v, 10, 0)
+			if err != nil {
+				return err
+			}
+			hdr.Gid = int(gid)
+		case paxAtime:
+			t, err := parsePAXTime(v)
+			if err != nil {
+				return err
+			}
+			hdr.AccessTime = t
+		case paxMtime:
+			t, err := parsePAXTime(v)
+			if err != nil {
+				return err
+			}
+			hdr.ModTime = t
+		case paxCtime:
+			t, err := parsePAXTime(v)
+			if err != nil {
+				return err
+			}
+			hdr.ChangeTime = t
+		case paxSize:
+			size, err := strconv.ParseInt(v, 10, 0)
+			if err != nil {
+				return err
+			}
+			hdr.Size = int64(size)
+		default:
+			if strings.HasPrefix(k, paxXattr) {
+				if hdr.Xattrs == nil {
+					hdr.Xattrs = make(map[string]string)
+				}
+				hdr.Xattrs[k[len(paxXattr):]] = v
+			} else if strings.HasPrefix(k, paxWindows) {
+				if hdr.Winheaders == nil {
+					hdr.Winheaders = make(map[string]string)
+				}
+				hdr.Winheaders[k[len(paxWindows):]] = v
+			}
+		}
+	}
+	return nil
+}
+
+// parsePAXTime takes a string of the form %d.%d as described in
+// the PAX specification.
+func parsePAXTime(t string) (time.Time, error) {
+	buf := []byte(t)
+	pos := bytes.IndexByte(buf, '.')
+	var seconds, nanoseconds int64
+	var err error
+	if pos == -1 {
+		seconds, err = strconv.ParseInt(t, 10, 0)
+		if err != nil {
+			return time.Time{}, err
+		}
+	} else {
+		seconds, err = strconv.ParseInt(string(buf[:pos]), 10, 0)
+		if err != nil {
+			return time.Time{}, err
+		}
+		nano_buf := string(buf[pos+1:])
+		// Pad as needed before converting to a decimal.
+		// For example .030 -> .030000000 -> 30000000 nanoseconds
+		if len(nano_buf) < maxNanoSecondIntSize {
+			// Right pad
+			nano_buf += strings.Repeat("0", maxNanoSecondIntSize-len(nano_buf))
+		} else if len(nano_buf) > maxNanoSecondIntSize {
+			// Right truncate
+			nano_buf = nano_buf[:maxNanoSecondIntSize]
+		}
+		nanoseconds, err = strconv.ParseInt(string(nano_buf), 10, 0)
+		if err != nil {
+			return time.Time{}, err
+		}
+	}
+	ts := time.Unix(seconds, nanoseconds)
+	return ts, nil
+}
+
+// parsePAX parses PAX headers.
+// If an extended header (type 'x') is invalid, ErrHeader is returned
+func parsePAX(r io.Reader) (map[string]string, error) {
+	buf, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, err
+	}
+	sbuf := string(buf)
+
+	// For GNU PAX sparse format 0.0 support.
+	// This function transforms the sparse format 0.0 headers into sparse format 0.1 headers.
+	var sparseMap bytes.Buffer
+
+	headers := make(map[string]string)
+	// Each record is constructed as
+	//     "%d %s=%s\n", length, keyword, value
+	for len(sbuf) > 0 {
+		key, value, residual, err := parsePAXRecord(sbuf)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		sbuf = residual
+
+		keyStr := string(key)
+		if keyStr == paxGNUSparseOffset || keyStr == paxGNUSparseNumBytes {
+			// GNU sparse format 0.0 special key. Write to sparseMap instead of using the headers map.
+			sparseMap.WriteString(value)
+			sparseMap.Write([]byte{','})
+		} else {
+			// Normal key. Set the value in the headers map.
+			headers[keyStr] = string(value)
+		}
+	}
+	if sparseMap.Len() != 0 {
+		// Add sparse info to headers, chopping off the extra comma
+		sparseMap.Truncate(sparseMap.Len() - 1)
+		headers[paxGNUSparseMap] = sparseMap.String()
+	}
+	return headers, nil
+}
+
+// parsePAXRecord parses the input PAX record string into a key-value pair.
+// If parsing is successful, it will slice off the currently read record and
+// return the remainder as r.
+//
+// A PAX record is of the following form:
+//	"%d %s=%s\n" % (size, key, value)
+func parsePAXRecord(s string) (k, v, r string, err error) {
+	// The size field ends at the first space.
+	sp := strings.IndexByte(s, ' ')
+	if sp == -1 {
+		return "", "", s, ErrHeader
+	}
+
+	// Parse the first token as a decimal integer.
+	n, perr := strconv.ParseInt(s[:sp], 10, 0) // Intentionally parse as native int
+	if perr != nil || n < 5 || int64(len(s)) < n {
+		return "", "", s, ErrHeader
+	}
+
+	// Extract everything between the space and the final newline.
+	rec, nl, rem := s[sp+1:n-1], s[n-1:n], s[n:]
+	if nl != "\n" {
+		return "", "", s, ErrHeader
+	}
+
+	// The first equals separates the key from the value.
+	eq := strings.IndexByte(rec, '=')
+	if eq == -1 {
+		return "", "", s, ErrHeader
+	}
+	return rec[:eq], rec[eq+1:], rem, nil
+}
+
+// parseString parses bytes as a NUL-terminated C-style string.
+// If a NUL byte is not found then the whole slice is returned as a string.
+func (*parser) parseString(b []byte) string {
+	n := 0
+	for n < len(b) && b[n] != 0 {
+		n++
+	}
+	return string(b[0:n])
+}
+
+// parseNumeric parses the input as being encoded in either base-256 or octal.
+// This function may return negative numbers.
+// If parsing fails or an integer overflow occurs, err will be set.
+func (p *parser) parseNumeric(b []byte) int64 {
+	// Check for base-256 (binary) format first.
+	// If the first bit is set, then all following bits constitute a two's
+	// complement encoded number in big-endian byte order.
+	if len(b) > 0 && b[0]&0x80 != 0 {
+		// Handling negative numbers relies on the following identity:
+		//	-a-1 == ^a
+		//
+		// If the number is negative, we use an inversion mask to invert the
+		// data bytes and treat the value as an unsigned number.
+		var inv byte // 0x00 if positive or zero, 0xff if negative
+		if b[0]&0x40 != 0 {
+			inv = 0xff
+		}
+
+		var x uint64
+		for i, c := range b {
+			c ^= inv // Inverts c only if inv is 0xff, otherwise does nothing
+			if i == 0 {
+				c &= 0x7f // Ignore signal bit in first byte
+			}
+			if (x >> 56) > 0 {
+				p.err = ErrHeader // Integer overflow
+				return 0
+			}
+			x = x<<8 | uint64(c)
+		}
+		if (x >> 63) > 0 {
+			p.err = ErrHeader // Integer overflow
+			return 0
+		}
+		if inv == 0xff {
+			return ^int64(x)
+		}
+		return int64(x)
+	}
+
+	// Normal case is base-8 (octal) format.
+	return p.parseOctal(b)
+}
+
+func (p *parser) parseOctal(b []byte) int64 {
+	// Because unused fields are filled with NULs, we need
+	// to skip leading NULs. Fields may also be padded with
+	// spaces or NULs.
+	// So we remove leading and trailing NULs and spaces to
+	// be sure.
+	b = bytes.Trim(b, " \x00")
+
+	if len(b) == 0 {
+		return 0
+	}
+	x, perr := strconv.ParseUint(p.parseString(b), 8, 64)
+	if perr != nil {
+		p.err = ErrHeader
+	}
+	return int64(x)
+}
+
+// skipUnread skips any unread bytes in the existing file entry, as well as any
+// alignment padding. It returns io.ErrUnexpectedEOF if any io.EOF is
+// encountered in the data portion; it is okay to hit io.EOF in the padding.
+//
+// Note that this function still works properly even when sparse files are being
+// used since numBytes returns the bytes remaining in the underlying io.Reader.
+func (tr *Reader) skipUnread() error {
+	dataSkip := tr.numBytes()      // Number of data bytes to skip
+	totalSkip := dataSkip + tr.pad // Total number of bytes to skip
+	tr.curr, tr.pad = nil, 0
+
+	// If possible, Seek to the last byte before the end of the data section.
+	// Do this because Seek is often lazy about reporting errors; this will mask
+	// the fact that the tar stream may be truncated. We can rely on the
+	// io.CopyN done shortly afterwards to trigger any IO errors.
+	var seekSkipped int64 // Number of bytes skipped via Seek
+	if sr, ok := tr.r.(io.Seeker); ok && dataSkip > 1 {
+		// Not all io.Seeker can actually Seek. For example, os.Stdin implements
+		// io.Seeker, but calling Seek always returns an error and performs
+		// no action. Thus, we try an innocent seek to the current position
+		// to see if Seek is really supported.
+		pos1, err := sr.Seek(0, os.SEEK_CUR)
+		if err == nil {
+			// Seek seems supported, so perform the real Seek.
+			pos2, err := sr.Seek(dataSkip-1, os.SEEK_CUR)
+			if err != nil {
+				tr.err = err
+				return tr.err
+			}
+			seekSkipped = pos2 - pos1
+		}
+	}
+
+	var copySkipped int64 // Number of bytes skipped via CopyN
+	copySkipped, tr.err = io.CopyN(ioutil.Discard, tr.r, totalSkip-seekSkipped)
+	if tr.err == io.EOF && seekSkipped+copySkipped < dataSkip {
+		tr.err = io.ErrUnexpectedEOF
+	}
+	return tr.err
+}
+
+func (tr *Reader) verifyChecksum(header []byte) bool {
+	if tr.err != nil {
+		return false
+	}
+
+	var p parser
+	given := p.parseOctal(header[148:156])
+	unsigned, signed := checksum(header)
+	return p.err == nil && (given == unsigned || given == signed)
+}
+
+// readHeader reads the next block header and assumes that the underlying reader
+// is already aligned to a block boundary.
+//
+// The err will be set to io.EOF only when one of the following occurs:
+//	* Exactly 0 bytes are read and EOF is hit.
+//	* Exactly 1 block of zeros is read and EOF is hit.
+//	* At least 2 blocks of zeros are read.
+func (tr *Reader) readHeader() *Header {
+	header := tr.hdrBuff[:]
+	copy(header, zeroBlock)
+
+	if _, tr.err = io.ReadFull(tr.r, header); tr.err != nil {
+		return nil // io.EOF is okay here
+	}
+
+	// Two blocks of zero bytes marks the end of the archive.
+	if bytes.Equal(header, zeroBlock[0:blockSize]) {
+		if _, tr.err = io.ReadFull(tr.r, header); tr.err != nil {
+			return nil // io.EOF is okay here
+		}
+		if bytes.Equal(header, zeroBlock[0:blockSize]) {
+			tr.err = io.EOF
+		} else {
+			tr.err = ErrHeader // zero block and then non-zero block
+		}
+		return nil
+	}
+
+	if !tr.verifyChecksum(header) {
+		tr.err = ErrHeader
+		return nil
+	}
+
+	// Unpack
+	var p parser
+	hdr := new(Header)
+	s := slicer(header)
+
+	hdr.Name = p.parseString(s.next(100))
+	hdr.Mode = p.parseNumeric(s.next(8))
+	hdr.Uid = int(p.parseNumeric(s.next(8)))
+	hdr.Gid = int(p.parseNumeric(s.next(8)))
+	hdr.Size = p.parseNumeric(s.next(12))
+	hdr.ModTime = time.Unix(p.parseNumeric(s.next(12)), 0)
+	s.next(8) // chksum
+	hdr.Typeflag = s.next(1)[0]
+	hdr.Linkname = p.parseString(s.next(100))
+
+	// The remainder of the header depends on the value of magic.
+	// The original (v7) version of tar had no explicit magic field,
+	// so its magic bytes, like the rest of the block, are NULs.
+	magic := string(s.next(8)) // contains version field as well.
+	var format string
+	switch {
+	case magic[:6] == "ustar\x00": // POSIX tar (1003.1-1988)
+		if string(header[508:512]) == "tar\x00" {
+			format = "star"
+		} else {
+			format = "posix"
+		}
+	case magic == "ustar  \x00": // old GNU tar
+		format = "gnu"
+	}
+
+	switch format {
+	case "posix", "gnu", "star":
+		hdr.Uname = p.parseString(s.next(32))
+		hdr.Gname = p.parseString(s.next(32))
+		devmajor := s.next(8)
+		devminor := s.next(8)
+		if hdr.Typeflag == TypeChar || hdr.Typeflag == TypeBlock {
+			hdr.Devmajor = p.parseNumeric(devmajor)
+			hdr.Devminor = p.parseNumeric(devminor)
+		}
+		var prefix string
+		switch format {
+		case "posix", "gnu":
+			prefix = p.parseString(s.next(155))
+		case "star":
+			prefix = p.parseString(s.next(131))
+			hdr.AccessTime = time.Unix(p.parseNumeric(s.next(12)), 0)
+			hdr.ChangeTime = time.Unix(p.parseNumeric(s.next(12)), 0)
+		}
+		if len(prefix) > 0 {
+			hdr.Name = prefix + "/" + hdr.Name
+		}
+	}
+
+	if p.err != nil {
+		tr.err = p.err
+		return nil
+	}
+
+	nb := hdr.Size
+	if isHeaderOnlyType(hdr.Typeflag) {
+		nb = 0
+	}
+	if nb < 0 {
+		tr.err = ErrHeader
+		return nil
+	}
+
+	// Set the current file reader.
+	tr.pad = -nb & (blockSize - 1) // blockSize is a power of two
+	tr.curr = &regFileReader{r: tr.r, nb: nb}
+
+	// Check for old GNU sparse format entry.
+	if hdr.Typeflag == TypeGNUSparse {
+		// Get the real size of the file.
+		hdr.Size = p.parseNumeric(header[483:495])
+		if p.err != nil {
+			tr.err = p.err
+			return nil
+		}
+
+		// Read the sparse map.
+		sp := tr.readOldGNUSparseMap(header)
+		if tr.err != nil {
+			return nil
+		}
+
+		// Current file is a GNU sparse file. Update the current file reader.
+		tr.curr, tr.err = newSparseFileReader(tr.curr, sp, hdr.Size)
+		if tr.err != nil {
+			return nil
+		}
+	}
+
+	return hdr
+}
+
+// readOldGNUSparseMap reads the sparse map as stored in the old GNU sparse format.
+// The sparse map is stored in the tar header if it's small enough. If it's larger than four entries,
+// then one or more extension headers are used to store the rest of the sparse map.
+func (tr *Reader) readOldGNUSparseMap(header []byte) []sparseEntry {
+	var p parser
+	isExtended := header[oldGNUSparseMainHeaderIsExtendedOffset] != 0
+	spCap := oldGNUSparseMainHeaderNumEntries
+	if isExtended {
+		spCap += oldGNUSparseExtendedHeaderNumEntries
+	}
+	sp := make([]sparseEntry, 0, spCap)
+	s := slicer(header[oldGNUSparseMainHeaderOffset:])
+
+	// Read the four entries from the main tar header
+	for i := 0; i < oldGNUSparseMainHeaderNumEntries; i++ {
+		offset := p.parseNumeric(s.next(oldGNUSparseOffsetSize))
+		numBytes := p.parseNumeric(s.next(oldGNUSparseNumBytesSize))
+		if p.err != nil {
+			tr.err = p.err
+			return nil
+		}
+		if offset == 0 && numBytes == 0 {
+			break
+		}
+		sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
+	}
+
+	for isExtended {
+		// There are more entries. Read an extension header and parse its entries.
+		sparseHeader := make([]byte, blockSize)
+		if _, tr.err = io.ReadFull(tr.r, sparseHeader); tr.err != nil {
+			return nil
+		}
+		isExtended = sparseHeader[oldGNUSparseExtendedHeaderIsExtendedOffset] != 0
+		s = slicer(sparseHeader)
+		for i := 0; i < oldGNUSparseExtendedHeaderNumEntries; i++ {
+			offset := p.parseNumeric(s.next(oldGNUSparseOffsetSize))
+			numBytes := p.parseNumeric(s.next(oldGNUSparseNumBytesSize))
+			if p.err != nil {
+				tr.err = p.err
+				return nil
+			}
+			if offset == 0 && numBytes == 0 {
+				break
+			}
+			sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
+		}
+	}
+	return sp
+}
+
+// readGNUSparseMap1x0 reads the sparse map as stored in GNU's PAX sparse format
+// version 1.0. The format of the sparse map consists of a series of
+// newline-terminated numeric fields. The first field is the number of entries
+// and is always present. Following this are the entries, consisting of two
+// fields (offset, numBytes). This function must stop reading at the end
+// boundary of the block containing the last newline.
+//
+// Note that the GNU manual says that numeric values should be encoded in octal
+// format. However, the GNU tar utility itself outputs these values in decimal.
+// As such, this library treats values as being encoded in decimal.
+func readGNUSparseMap1x0(r io.Reader) ([]sparseEntry, error) {
+	var cntNewline int64
+	var buf bytes.Buffer
+	var blk = make([]byte, blockSize)
+
+	// feedTokens copies data in numBlock chunks from r into buf until there are
+	// at least cnt newlines in buf. It will not read more blocks than needed.
+	var feedTokens = func(cnt int64) error {
+		for cntNewline < cnt {
+			if _, err := io.ReadFull(r, blk); err != nil {
+				if err == io.EOF {
+					err = io.ErrUnexpectedEOF
+				}
+				return err
+			}
+			buf.Write(blk)
+			for _, c := range blk {
+				if c == '\n' {
+					cntNewline++
+				}
+			}
+		}
+		return nil
+	}
+
+	// nextToken gets the next token delimited by a newline. This assumes that
+	// at least one newline exists in the buffer.
+	var nextToken = func() string {
+		cntNewline--
+		tok, _ := buf.ReadString('\n')
+		return tok[:len(tok)-1] // Cut off newline
+	}
+
+	// Parse for the number of entries.
+	// Use integer overflow resistant math to check this.
+	if err := feedTokens(1); err != nil {
+		return nil, err
+	}
+	numEntries, err := strconv.ParseInt(nextToken(), 10, 0) // Intentionally parse as native int
+	if err != nil || numEntries < 0 || int(2*numEntries) < int(numEntries) {
+		return nil, ErrHeader
+	}
+
+	// Parse for all member entries.
+	// numEntries is trusted after this since a potential attacker must have
+	// committed resources proportional to what this library used.
+	if err := feedTokens(2 * numEntries); err != nil {
+		return nil, err
+	}
+	sp := make([]sparseEntry, 0, numEntries)
+	for i := int64(0); i < numEntries; i++ {
+		offset, err := strconv.ParseInt(nextToken(), 10, 64)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		numBytes, err := strconv.ParseInt(nextToken(), 10, 64)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
+	}
+	return sp, nil
+}
+
+// readGNUSparseMap0x1 reads the sparse map as stored in GNU's PAX sparse format
+// version 0.1. The sparse map is stored in the PAX headers.
+func readGNUSparseMap0x1(extHdrs map[string]string) ([]sparseEntry, error) {
+	// Get number of entries.
+	// Use integer overflow resistant math to check this.
+	numEntriesStr := extHdrs[paxGNUSparseNumBlocks]
+	numEntries, err := strconv.ParseInt(numEntriesStr, 10, 0) // Intentionally parse as native int
+	if err != nil || numEntries < 0 || int(2*numEntries) < int(numEntries) {
+		return nil, ErrHeader
+	}
+
+	// There should be two numbers in sparseMap for each entry.
+	sparseMap := strings.Split(extHdrs[paxGNUSparseMap], ",")
+	if int64(len(sparseMap)) != 2*numEntries {
+		return nil, ErrHeader
+	}
+
+	// Loop through the entries in the sparse map.
+	// numEntries is trusted now.
+	sp := make([]sparseEntry, 0, numEntries)
+	for i := int64(0); i < numEntries; i++ {
+		offset, err := strconv.ParseInt(sparseMap[2*i], 10, 64)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		numBytes, err := strconv.ParseInt(sparseMap[2*i+1], 10, 64)
+		if err != nil {
+			return nil, ErrHeader
+		}
+		sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
+	}
+	return sp, nil
+}
+
+// numBytes returns the number of bytes left to read in the current file's entry
+// in the tar archive, or 0 if there is no current file.
+func (tr *Reader) numBytes() int64 {
+	if tr.curr == nil {
+		// No current file, so no bytes
+		return 0
+	}
+	return tr.curr.numBytes()
+}
+
+// Read reads from the current entry in the tar archive.
+// It returns 0, io.EOF when it reaches the end of that entry,
+// until Next is called to advance to the next entry.
+//
+// Calling Read on special types like TypeLink, TypeSymLink, TypeChar,
+// TypeBlock, TypeDir, and TypeFifo returns 0, io.EOF regardless of what
+// the Header.Size claims.
+func (tr *Reader) Read(b []byte) (n int, err error) {
+	if tr.err != nil {
+		return 0, tr.err
+	}
+	if tr.curr == nil {
+		return 0, io.EOF
+	}
+
+	n, err = tr.curr.Read(b)
+	if err != nil && err != io.EOF {
+		tr.err = err
+	}
+	return
+}
+
+func (rfr *regFileReader) Read(b []byte) (n int, err error) {
+	if rfr.nb == 0 {
+		// file consumed
+		return 0, io.EOF
+	}
+	if int64(len(b)) > rfr.nb {
+		b = b[0:rfr.nb]
+	}
+	n, err = rfr.r.Read(b)
+	rfr.nb -= int64(n)
+
+	if err == io.EOF && rfr.nb > 0 {
+		err = io.ErrUnexpectedEOF
+	}
+	return
+}
+
+// numBytes returns the number of bytes left to read in the file's data in the tar archive.
+func (rfr *regFileReader) numBytes() int64 {
+	return rfr.nb
+}
+
+// newSparseFileReader creates a new sparseFileReader, but validates all of the
+// sparse entries before doing so.
+func newSparseFileReader(rfr numBytesReader, sp []sparseEntry, total int64) (*sparseFileReader, error) {
+	if total < 0 {
+		return nil, ErrHeader // Total size cannot be negative
+	}
+
+	// Validate all sparse entries. These are the same checks as performed by
+	// the BSD tar utility.
+	for i, s := range sp {
+		switch {
+		case s.offset < 0 || s.numBytes < 0:
+			return nil, ErrHeader // Negative values are never okay
+		case s.offset > math.MaxInt64-s.numBytes:
+			return nil, ErrHeader // Integer overflow with large length
+		case s.offset+s.numBytes > total:
+			return nil, ErrHeader // Region extends beyond the "real" size
+		case i > 0 && sp[i-1].offset+sp[i-1].numBytes > s.offset:
+			return nil, ErrHeader // Regions can't overlap and must be in order
+		}
+	}
+	return &sparseFileReader{rfr: rfr, sp: sp, total: total}, nil
+}
+
+// readHole reads a sparse hole ending at endOffset.
+func (sfr *sparseFileReader) readHole(b []byte, endOffset int64) int {
+	n64 := endOffset - sfr.pos
+	if n64 > int64(len(b)) {
+		n64 = int64(len(b))
+	}
+	n := int(n64)
+	for i := 0; i < n; i++ {
+		b[i] = 0
+	}
+	sfr.pos += n64
+	return n
+}
+
+// Read reads the sparse file data in expanded form.
+func (sfr *sparseFileReader) Read(b []byte) (n int, err error) {
+	// Skip past all empty fragments.
+	for len(sfr.sp) > 0 && sfr.sp[0].numBytes == 0 {
+		sfr.sp = sfr.sp[1:]
+	}
+
+	// If there are no more fragments, then it is possible that there
+	// is one last sparse hole.
+	if len(sfr.sp) == 0 {
+		// This behavior matches the BSD tar utility.
+		// However, GNU tar stops returning data even if sfr.total is unmet.
+		if sfr.pos < sfr.total {
+			return sfr.readHole(b, sfr.total), nil
+		}
+		return 0, io.EOF
+	}
+
+	// In front of a data fragment, so read a hole.
+	if sfr.pos < sfr.sp[0].offset {
+		return sfr.readHole(b, sfr.sp[0].offset), nil
+	}
+
+	// In a data fragment, so read from it.
+	// This math is overflow free since we verify that offset and numBytes can
+	// be safely added when creating the sparseFileReader.
+	endPos := sfr.sp[0].offset + sfr.sp[0].numBytes // End offset of fragment
+	bytesLeft := endPos - sfr.pos                   // Bytes left in fragment
+	if int64(len(b)) > bytesLeft {
+		b = b[:bytesLeft]
+	}
+
+	n, err = sfr.rfr.Read(b)
+	sfr.pos += int64(n)
+	if err == io.EOF {
+		if sfr.pos < endPos {
+			err = io.ErrUnexpectedEOF // There was supposed to be more data
+		} else if sfr.pos < sfr.total {
+			err = nil // There is still an implicit sparse hole at the end
+		}
+	}
+
+	if sfr.pos == endPos {
+		sfr.sp = sfr.sp[1:] // We are done with this fragment, so pop it
+	}
+	return n, err
+}
+
+// numBytes returns the number of bytes left to read in the sparse file's
+// sparse-encoded data in the tar archive.
+func (sfr *sparseFileReader) numBytes() int64 {
+	return sfr.rfr.numBytes()
+}

vendor/github.com/Microsoft/go-winio/archive/tar/stat_atim.go

@@ -0,0 +1,20 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux dragonfly openbsd solaris
+
+package tar
+
+import (
+	"syscall"
+	"time"
+)
+
+func statAtime(st *syscall.Stat_t) time.Time {
+	return time.Unix(st.Atim.Unix())
+}
+
+func statCtime(st *syscall.Stat_t) time.Time {
+	return time.Unix(st.Ctim.Unix())
+}

vendor/github.com/Microsoft/go-winio/archive/tar/stat_atimespec.go

@@ -0,0 +1,20 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin freebsd netbsd
+
+package tar
+
+import (
+	"syscall"
+	"time"
+)
+
+func statAtime(st *syscall.Stat_t) time.Time {
+	return time.Unix(st.Atimespec.Unix())
+}
+
+func statCtime(st *syscall.Stat_t) time.Time {
+	return time.Unix(st.Ctimespec.Unix())
+}

vendor/github.com/Microsoft/go-winio/archive/tar/stat_unix.go

@@ -0,0 +1,32 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux darwin dragonfly freebsd openbsd netbsd solaris
+
+package tar
+
+import (
+	"os"
+	"syscall"
+)
+
+func init() {
+	sysStat = statUnix
+}
+
+func statUnix(fi os.FileInfo, h *Header) error {
+	sys, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return nil
+	}
+	h.Uid = int(sys.Uid)
+	h.Gid = int(sys.Gid)
+	// TODO(bradfitz): populate username & group.  os/user
+	// doesn't cache LookupId lookups, and lacks group
+	// lookup functions.
+	h.AccessTime = statAtime(sys)
+	h.ChangeTime = statCtime(sys)
+	// TODO(bradfitz): major/minor device numbers?
+	return nil
+}

vendor/github.com/Microsoft/go-winio/archive/tar/writer.go

@@ -0,0 +1,419 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tar
+
+// TODO(dsymonds):
+// - catch more errors (no first header, etc.)
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"path"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var (
+	ErrWriteTooLong    = errors.New("archive/tar: write too long")
+	ErrFieldTooLong    = errors.New("archive/tar: header field too long")
+	ErrWriteAfterClose = errors.New("archive/tar: write after close")
+	errInvalidHeader   = errors.New("archive/tar: header field too long or contains invalid values")
+)
+
+// A Writer provides sequential writing of a tar archive in POSIX.1 format.
+// A tar archive consists of a sequence of files.
+// Call WriteHeader to begin a new file, and then call Write to supply that file's data,
+// writing at most hdr.Size bytes in total.
+type Writer struct {
+	w          io.Writer
+	err        error
+	nb         int64 // number of unwritten bytes for current file entry
+	pad        int64 // amount of padding to write after current file entry
+	closed     bool
+	usedBinary bool            // whether the binary numeric field extension was used
+	preferPax  bool            // use pax header instead of binary numeric header
+	hdrBuff    [blockSize]byte // buffer to use in writeHeader when writing a regular header
+	paxHdrBuff [blockSize]byte // buffer to use in writeHeader when writing a pax header
+}
+
+type formatter struct {
+	err error // Last error seen
+}
+
+// NewWriter creates a new Writer writing to w.
+func NewWriter(w io.Writer) *Writer { return &Writer{w: w} }
+
+// Flush finishes writing the current file (optional).
+func (tw *Writer) Flush() error {
+	if tw.nb > 0 {
+		tw.err = fmt.Errorf("archive/tar: missed writing %d bytes", tw.nb)
+		return tw.err
+	}
+
+	n := tw.nb + tw.pad
+	for n > 0 && tw.err == nil {
+		nr := n
+		if nr > blockSize {
+			nr = blockSize
+		}
+		var nw int
+		nw, tw.err = tw.w.Write(zeroBlock[0:nr])
+		n -= int64(nw)
+	}
+	tw.nb = 0
+	tw.pad = 0
+	return tw.err
+}
+
+// Write s into b, terminating it with a NUL if there is room.
+func (f *formatter) formatString(b []byte, s string) {
+	if len(s) > len(b) {
+		f.err = ErrFieldTooLong
+		return
+	}
+	ascii := toASCII(s)
+	copy(b, ascii)
+	if len(ascii) < len(b) {
+		b[len(ascii)] = 0
+	}
+}
+
+// Encode x as an octal ASCII string and write it into b with leading zeros.
+func (f *formatter) formatOctal(b []byte, x int64) {
+	s := strconv.FormatInt(x, 8)
+	// leading zeros, but leave room for a NUL.
+	for len(s)+1 < len(b) {
+		s = "0" + s
+	}
+	f.formatString(b, s)
+}
+
+// fitsInBase256 reports whether x can be encoded into n bytes using base-256
+// encoding. Unlike octal encoding, base-256 encoding does not require that the
+// string ends with a NUL character. Thus, all n bytes are available for output.
+//
+// If operating in binary mode, this assumes strict GNU binary mode; which means
+// that the first byte can only be either 0x80 or 0xff. Thus, the first byte is
+// equivalent to the sign bit in two's complement form.
+func fitsInBase256(n int, x int64) bool {
+	var binBits = uint(n-1) * 8
+	return n >= 9 || (x >= -1<<binBits && x < 1<<binBits)
+}
+
+// Write x into b, as binary (GNUtar/star extension).
+func (f *formatter) formatNumeric(b []byte, x int64) {
+	if fitsInBase256(len(b), x) {
+		for i := len(b) - 1; i >= 0; i-- {
+			b[i] = byte(x)
+			x >>= 8
+		}
+		b[0] |= 0x80 // Highest bit indicates binary format
+		return
+	}
+
+	f.formatOctal(b, 0) // Last resort, just write zero
+	f.err = ErrFieldTooLong
+}
+
+var (
+	minTime = time.Unix(0, 0)
+	// There is room for 11 octal digits (33 bits) of mtime.
+	maxTime = minTime.Add((1<<33 - 1) * time.Second)
+)
+
+// WriteHeader writes hdr and prepares to accept the file's contents.
+// WriteHeader calls Flush if it is not the first header.
+// Calling after a Close will return ErrWriteAfterClose.
+func (tw *Writer) WriteHeader(hdr *Header) error {
+	return tw.writeHeader(hdr, true)
+}
+
+// WriteHeader writes hdr and prepares to accept the file's contents.
+// WriteHeader calls Flush if it is not the first header.
+// Calling after a Close will return ErrWriteAfterClose.
+// As this method is called internally by writePax header to allow it to
+// suppress writing the pax header.
+func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
+	if tw.closed {
+		return ErrWriteAfterClose
+	}
+	if tw.err == nil {
+		tw.Flush()
+	}
+	if tw.err != nil {
+		return tw.err
+	}
+
+	// a map to hold pax header records, if any are needed
+	paxHeaders := make(map[string]string)
+
+	// TODO(shanemhansen): we might want to use PAX headers for
+	// subsecond time resolution, but for now let's just capture
+	// too long fields or non ascii characters
+
+	var f formatter
+	var header []byte
+
+	// We need to select which scratch buffer to use carefully,
+	// since this method is called recursively to write PAX headers.
+	// If allowPax is true, this is the non-recursive call, and we will use hdrBuff.
+	// If allowPax is false, we are being called by writePAXHeader, and hdrBuff is
+	// already being used by the non-recursive call, so we must use paxHdrBuff.
+	header = tw.hdrBuff[:]
+	if !allowPax {
+		header = tw.paxHdrBuff[:]
+	}
+	copy(header, zeroBlock)
+	s := slicer(header)
+
+	// Wrappers around formatter that automatically sets paxHeaders if the
+	// argument extends beyond the capacity of the input byte slice.
+	var formatString = func(b []byte, s string, paxKeyword string) {
+		needsPaxHeader := paxKeyword != paxNone && len(s) > len(b) || !isASCII(s)
+		if needsPaxHeader {
+			paxHeaders[paxKeyword] = s
+			return
+		}
+		f.formatString(b, s)
+	}
+	var formatNumeric = func(b []byte, x int64, paxKeyword string) {
+		// Try octal first.
+		s := strconv.FormatInt(x, 8)
+		if len(s) < len(b) {
+			f.formatOctal(b, x)
+			return
+		}
+
+		// If it is too long for octal, and PAX is preferred, use a PAX header.
+		if paxKeyword != paxNone && tw.preferPax {
+			f.formatOctal(b, 0)
+			s := strconv.FormatInt(x, 10)
+			paxHeaders[paxKeyword] = s
+			return
+		}
+
+		tw.usedBinary = true
+		f.formatNumeric(b, x)
+	}
+
+	// keep a reference to the filename to allow to overwrite it later if we detect that we can use ustar longnames instead of pax
+	pathHeaderBytes := s.next(fileNameSize)
+
+	formatString(pathHeaderBytes, hdr.Name, paxPath)
+
+	// Handle out of range ModTime carefully.
+	var modTime int64
+	if !hdr.ModTime.Before(minTime) && !hdr.ModTime.After(maxTime) {
+		modTime = hdr.ModTime.Unix()
+	}
+
+	f.formatOctal(s.next(8), hdr.Mode)               // 100:108
+	formatNumeric(s.next(8), int64(hdr.Uid), paxUid) // 108:116
+	formatNumeric(s.next(8), int64(hdr.Gid), paxGid) // 116:124
+	formatNumeric(s.next(12), hdr.Size, paxSize)     // 124:136
+	formatNumeric(s.next(12), modTime, paxNone)      // 136:148 --- consider using pax for finer granularity
+	s.next(8)                                        // chksum (148:156)
+	s.next(1)[0] = hdr.Typeflag                      // 156:157
+
+	formatString(s.next(100), hdr.Linkname, paxLinkpath)
+
+	copy(s.next(8), []byte("ustar\x0000"))          // 257:265
+	formatString(s.next(32), hdr.Uname, paxUname)   // 265:297
+	formatString(s.next(32), hdr.Gname, paxGname)   // 297:329
+	formatNumeric(s.next(8), hdr.Devmajor, paxNone) // 329:337
+	formatNumeric(s.next(8), hdr.Devminor, paxNone) // 337:345
+
+	// keep a reference to the prefix to allow to overwrite it later if we detect that we can use ustar longnames instead of pax
+	prefixHeaderBytes := s.next(155)
+	formatString(prefixHeaderBytes, "", paxNone) // 345:500  prefix
+
+	// Use the GNU magic instead of POSIX magic if we used any GNU extensions.
+	if tw.usedBinary {
+		copy(header[257:265], []byte("ustar  \x00"))
+	}
+
+	_, paxPathUsed := paxHeaders[paxPath]
+	// try to use a ustar header when only the name is too long
+	if !tw.preferPax && len(paxHeaders) == 1 && paxPathUsed {
+		prefix, suffix, ok := splitUSTARPath(hdr.Name)
+		if ok {
+			// Since we can encode in USTAR format, disable PAX header.
+			delete(paxHeaders, paxPath)
+
+			// Update the path fields
+			formatString(pathHeaderBytes, suffix, paxNone)
+			formatString(prefixHeaderBytes, prefix, paxNone)
+		}
+	}
+
+	// The chksum field is terminated by a NUL and a space.
+	// This is different from the other octal fields.
+	chksum, _ := checksum(header)
+	f.formatOctal(header[148:155], chksum) // Never fails
+	header[155] = ' '
+
+	// Check if there were any formatting errors.
+	if f.err != nil {
+		tw.err = f.err
+		return tw.err
+	}
+
+	if allowPax {
+		for k, v := range hdr.Xattrs {
+			paxHeaders[paxXattr+k] = v
+		}
+		for k, v := range hdr.Winheaders {
+			paxHeaders[paxWindows+k] = v
+		}
+	}
+
+	if len(paxHeaders) > 0 {
+		if !allowPax {
+			return errInvalidHeader
+		}
+		if err := tw.writePAXHeader(hdr, paxHeaders); err != nil {
+			return err
+		}
+	}
+	tw.nb = int64(hdr.Size)
+	tw.pad = (blockSize - (tw.nb % blockSize)) % blockSize
+
+	_, tw.err = tw.w.Write(header)
+	return tw.err
+}
+
+// splitUSTARPath splits a path according to USTAR prefix and suffix rules.
+// If the path is not splittable, then it will return ("", "", false).
+func splitUSTARPath(name string) (prefix, suffix string, ok bool) {
+	length := len(name)
+	if length <= fileNameSize || !isASCII(name) {
+		return "", "", false
+	} else if length > fileNamePrefixSize+1 {
+		length = fileNamePrefixSize + 1
+	} else if name[length-1] == '/' {
+		length--
+	}
+
+	i := strings.LastIndex(name[:length], "/")
+	nlen := len(name) - i - 1 // nlen is length of suffix
+	plen := i                 // plen is length of prefix
+	if i <= 0 || nlen > fileNameSize || nlen == 0 || plen > fileNamePrefixSize {
+		return "", "", false
+	}
+	return name[:i], name[i+1:], true
+}
+
+// writePaxHeader writes an extended pax header to the
+// archive.
+func (tw *Writer) writePAXHeader(hdr *Header, paxHeaders map[string]string) error {
+	// Prepare extended header
+	ext := new(Header)
+	ext.Typeflag = TypeXHeader
+	// Setting ModTime is required for reader parsing to
+	// succeed, and seems harmless enough.
+	ext.ModTime = hdr.ModTime
+	// The spec asks that we namespace our pseudo files
+	// with the current pid.  However, this results in differing outputs
+	// for identical inputs.  As such, the constant 0 is now used instead.
+	// golang.org/issue/12358
+	dir, file := path.Split(hdr.Name)
+	fullName := path.Join(dir, "PaxHeaders.0", file)
+
+	ascii := toASCII(fullName)
+	if len(ascii) > 100 {
+		ascii = ascii[:100]
+	}
+	ext.Name = ascii
+	// Construct the body
+	var buf bytes.Buffer
+
+	// Keys are sorted before writing to body to allow deterministic output.
+	var keys []string
+	for k := range paxHeaders {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+
+	for _, k := range keys {
+		fmt.Fprint(&buf, formatPAXRecord(k, paxHeaders[k]))
+	}
+
+	ext.Size = int64(len(buf.Bytes()))
+	if err := tw.writeHeader(ext, false); err != nil {
+		return err
+	}
+	if _, err := tw.Write(buf.Bytes()); err != nil {
+		return err
+	}
+	if err := tw.Flush(); err != nil {
+		return err
+	}
+	return nil
+}
+
+// formatPAXRecord formats a single PAX record, prefixing it with the
+// appropriate length.
+func formatPAXRecord(k, v string) string {
+	const padding = 3 // Extra padding for ' ', '=', and '\n'
+	size := len(k) + len(v) + padding
+	size += len(strconv.Itoa(size))
+	record := fmt.Sprintf("%d %s=%s\n", size, k, v)
+
+	// Final adjustment if adding size field increased the record size.
+	if len(record) != size {
+		size = len(record)
+		record = fmt.Sprintf("%d %s=%s\n", size, k, v)
+	}
+	return record
+}
+
+// Write writes to the current entry in the tar archive.
+// Write returns the error ErrWriteTooLong if more than
+// hdr.Size bytes are written after WriteHeader.
+func (tw *Writer) Write(b []byte) (n int, err error) {
+	if tw.closed {
+		err = ErrWriteAfterClose
+		return
+	}
+	overwrite := false
+	if int64(len(b)) > tw.nb {
+		b = b[0:tw.nb]
+		overwrite = true
+	}
+	n, err = tw.w.Write(b)
+	tw.nb -= int64(n)
+	if err == nil && overwrite {
+		err = ErrWriteTooLong
+		return
+	}
+	tw.err = err
+	return
+}
+
+// Close closes the tar archive, flushing any unwritten
+// data to the underlying writer.
+func (tw *Writer) Close() error {
+	if tw.err != nil || tw.closed {
+		return tw.err
+	}
+	tw.Flush()
+	tw.closed = true
+	if tw.err != nil {
+		return tw.err
+	}
+
+	// trailer: two zero blocks
+	for i := 0; i < 2; i++ {
+		_, tw.err = tw.w.Write(zeroBlock)
+		if tw.err != nil {
+			break
+		}
+	}
+	return tw.err
+}

vendor/github.com/Microsoft/go-winio/backup.go

@@ -0,0 +1,241 @@
+package winio
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"runtime"
+	"syscall"
+	"unicode/utf16"
+)
+
+//sys backupRead(h syscall.Handle, b []byte, bytesRead *uint32, abort bool, processSecurity bool, context *uintptr) (err error) = BackupRead
+//sys backupWrite(h syscall.Handle, b []byte, bytesWritten *uint32, abort bool, processSecurity bool, context *uintptr) (err error) = BackupWrite
+
+const (
+	BackupData = uint32(iota + 1)
+	BackupEaData
+	BackupSecurity
+	BackupAlternateData
+	BackupLink
+	BackupPropertyData
+	BackupObjectId
+	BackupReparseData
+	BackupSparseBlock
+	BackupTxfsData
+
+	StreamSparseAttributes = uint32(8)
+)
+
+// BackupHeader represents a backup stream of a file.
+type BackupHeader struct {
+	Id         uint32 // The backup stream ID
+	Attributes uint32 // Stream attributes
+	Size       int64  // The size of the stream in bytes
+	Name       string // The name of the stream (for BackupAlternateData only).
+	Offset     int64  // The offset of the stream in the file (for BackupSparseBlock only).
+}
+
+type win32StreamId struct {
+	StreamId   uint32
+	Attributes uint32
+	Size       uint64
+	NameSize   uint32
+}
+
+// BackupStreamReader reads from a stream produced by the BackupRead Win32 API and produces a series
+// of BackupHeader values.
+type BackupStreamReader struct {
+	r         io.Reader
+	bytesLeft int64
+}
+
+// NewBackupStreamReader produces a BackupStreamReader from any io.Reader.
+func NewBackupStreamReader(r io.Reader) *BackupStreamReader {
+	return &BackupStreamReader{r, 0}
+}
+
+// Next returns the next backup stream and prepares for calls to Write(). It skips the remainder of the current stream if
+// it was not completely read.
+func (r *BackupStreamReader) Next() (*BackupHeader, error) {
+	if r.bytesLeft > 0 {
+		if _, err := io.Copy(ioutil.Discard, r); err != nil {
+			return nil, err
+		}
+	}
+	var wsi win32StreamId
+	if err := binary.Read(r.r, binary.LittleEndian, &wsi); err != nil {
+		return nil, err
+	}
+	hdr := &BackupHeader{
+		Id:         wsi.StreamId,
+		Attributes: wsi.Attributes,
+		Size:       int64(wsi.Size),
+	}
+	if wsi.NameSize != 0 {
+		name := make([]uint16, int(wsi.NameSize/2))
+		if err := binary.Read(r.r, binary.LittleEndian, name); err != nil {
+			return nil, err
+		}
+		hdr.Name = syscall.UTF16ToString(name)
+	}
+	if wsi.StreamId == BackupSparseBlock {
+		if err := binary.Read(r.r, binary.LittleEndian, &hdr.Offset); err != nil {
+			return nil, err
+		}
+		hdr.Size -= 8
+	}
+	r.bytesLeft = hdr.Size
+	return hdr, nil
+}
+
+// Read reads from the current backup stream.
+func (r *BackupStreamReader) Read(b []byte) (int, error) {
+	if r.bytesLeft == 0 {
+		return 0, io.EOF
+	}
+	if int64(len(b)) > r.bytesLeft {
+		b = b[:r.bytesLeft]
+	}
+	n, err := r.r.Read(b)
+	r.bytesLeft -= int64(n)
+	if err == io.EOF {
+		err = io.ErrUnexpectedEOF
+	} else if r.bytesLeft == 0 && err == nil {
+		err = io.EOF
+	}
+	return n, err
+}
+
+// BackupStreamWriter writes a stream compatible with the BackupWrite Win32 API.
+type BackupStreamWriter struct {
+	w         io.Writer
+	bytesLeft int64
+}
+
+// NewBackupStreamWriter produces a BackupStreamWriter on top of an io.Writer.
+func NewBackupStreamWriter(w io.Writer) *BackupStreamWriter {
+	return &BackupStreamWriter{w, 0}
+}
+
+// WriteHeader writes the next backup stream header and prepares for calls to Write().
+func (w *BackupStreamWriter) WriteHeader(hdr *BackupHeader) error {
+	if w.bytesLeft != 0 {
+		return fmt.Errorf("missing %d bytes", w.bytesLeft)
+	}
+	name := utf16.Encode([]rune(hdr.Name))
+	wsi := win32StreamId{
+		StreamId:   hdr.Id,
+		Attributes: hdr.Attributes,
+		Size:       uint64(hdr.Size),
+		NameSize:   uint32(len(name) * 2),
+	}
+	if hdr.Id == BackupSparseBlock {
+		// Include space for the int64 block offset
+		wsi.Size += 8
+	}
+	if err := binary.Write(w.w, binary.LittleEndian, &wsi); err != nil {
+		return err
+	}
+	if len(name) != 0 {
+		if err := binary.Write(w.w, binary.LittleEndian, name); err != nil {
+			return err
+		}
+	}
+	if hdr.Id == BackupSparseBlock {
+		if err := binary.Write(w.w, binary.LittleEndian, hdr.Offset); err != nil {
+			return err
+		}
+	}
+	w.bytesLeft = hdr.Size
+	return nil
+}
+
+// Write writes to the current backup stream.
+func (w *BackupStreamWriter) Write(b []byte) (int, error) {
+	if w.bytesLeft < int64(len(b)) {
+		return 0, fmt.Errorf("too many bytes by %d", int64(len(b))-w.bytesLeft)
+	}
+	n, err := w.w.Write(b)
+	w.bytesLeft -= int64(n)
+	return n, err
+}
+
+// BackupFileReader provides an io.ReadCloser interface on top of the BackupRead Win32 API.
+type BackupFileReader struct {
+	f               *os.File
+	includeSecurity bool
+	ctx             uintptr
+}
+
+// NewBackupFileReader returns a new BackupFileReader from a file handle. If includeSecurity is true,
+// Read will attempt to read the security descriptor of the file.
+func NewBackupFileReader(f *os.File, includeSecurity bool) *BackupFileReader {
+	r := &BackupFileReader{f, includeSecurity, 0}
+	runtime.SetFinalizer(r, func(r *BackupFileReader) { r.Close() })
+	return r
+}
+
+// Read reads a backup stream from the file by calling the Win32 API BackupRead().
+func (r *BackupFileReader) Read(b []byte) (int, error) {
+	var bytesRead uint32
+	err := backupRead(syscall.Handle(r.f.Fd()), b, &bytesRead, false, r.includeSecurity, &r.ctx)
+	if err != nil {
+		return 0, &os.PathError{"BackupRead", r.f.Name(), err}
+	}
+	if bytesRead == 0 {
+		return 0, io.EOF
+	}
+	return int(bytesRead), nil
+}
+
+// Close frees Win32 resources associated with the BackupFileReader. It does not close
+// the underlying file.
+func (r *BackupFileReader) Close() error {
+	if r.ctx != 0 {
+		backupRead(syscall.Handle(r.f.Fd()), nil, nil, true, false, &r.ctx)
+		r.ctx = 0
+	}
+	return nil
+}
+
+// BackupFileWriter provides an io.WriteCloser interface on top of the BackupWrite Win32 API.
+type BackupFileWriter struct {
+	f               *os.File
+	includeSecurity bool
+	ctx             uintptr
+}
+
+// NewBackupFileWrtier returns a new BackupFileWriter from a file handle. If includeSecurity is true,
+// Write() will attempt to restore the security descriptor from the stream.
+func NewBackupFileWriter(f *os.File, includeSecurity bool) *BackupFileWriter {
+	w := &BackupFileWriter{f, includeSecurity, 0}
+	runtime.SetFinalizer(w, func(w *BackupFileWriter) { w.Close() })
+	return w
+}
+
+// Write restores a portion of the file using the provided backup stream.
+func (w *BackupFileWriter) Write(b []byte) (int, error) {
+	var bytesWritten uint32
+	err := backupWrite(syscall.Handle(w.f.Fd()), b, &bytesWritten, false, w.includeSecurity, &w.ctx)
+	if err != nil {
+		return 0, &os.PathError{"BackupWrite", w.f.Name(), err}
+	}
+	if int(bytesWritten) != len(b) {
+		return int(bytesWritten), errors.New("not all bytes could be written")
+	}
+	return len(b), nil
+}
+
+// Close frees Win32 resources associated with the BackupFileWriter. It does not
+// close the underlying file.
+func (w *BackupFileWriter) Close() error {
+	if w.ctx != 0 {
+		backupWrite(syscall.Handle(w.f.Fd()), nil, nil, true, false, &w.ctx)
+		w.ctx = 0
+	}
+	return nil
+}

vendor/github.com/Microsoft/go-winio/backuptar/tar.go

@@ -0,0 +1,362 @@
+package backuptar
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/Microsoft/go-winio"
+	"github.com/Microsoft/go-winio/archive/tar" // until archive/tar supports pax extensions in its interface
+)
+
+const (
+	c_ISUID  = 04000   // Set uid
+	c_ISGID  = 02000   // Set gid
+	c_ISVTX  = 01000   // Save text (sticky bit)
+	c_ISDIR  = 040000  // Directory
+	c_ISFIFO = 010000  // FIFO
+	c_ISREG  = 0100000 // Regular file
+	c_ISLNK  = 0120000 // Symbolic link
+	c_ISBLK  = 060000  // Block special file
+	c_ISCHR  = 020000  // Character special file
+	c_ISSOCK = 0140000 // Socket
+)
+
+const (
+	hdrFileAttributes     = "fileattr"
+	hdrAccessTime         = "accesstime"
+	hdrChangeTime         = "changetime"
+	hdrCreateTime         = "createtime"
+	hdrWriteTime          = "writetime"
+	hdrSecurityDescriptor = "sd"
+	hdrMountPoint         = "mountpoint"
+)
+
+func writeZeroes(w io.Writer, count int64) error {
+	buf := make([]byte, 8192)
+	c := len(buf)
+	for i := int64(0); i < count; i += int64(c) {
+		if int64(c) > count-i {
+			c = int(count - i)
+		}
+		_, err := w.Write(buf[:c])
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func copySparse(t *tar.Writer, br *winio.BackupStreamReader) error {
+	curOffset := int64(0)
+	for {
+		bhdr, err := br.Next()
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
+		if err != nil {
+			return err
+		}
+		if bhdr.Id != winio.BackupSparseBlock {
+			return fmt.Errorf("unexpected stream %d", bhdr.Id)
+		}
+
+		// archive/tar does not support writing sparse files
+		// so just write zeroes to catch up to the current offset.
+		err = writeZeroes(t, bhdr.Offset-curOffset)
+		if bhdr.Size == 0 {
+			break
+		}
+		n, err := io.Copy(t, br)
+		if err != nil {
+			return err
+		}
+		curOffset = bhdr.Offset + n
+	}
+	return nil
+}
+
+func win32TimeFromTar(key string, hdrs map[string]string, unixTime time.Time) syscall.Filetime {
+	if s, ok := hdrs[key]; ok {
+		n, err := strconv.ParseUint(s, 10, 64)
+		if err == nil {
+			return syscall.Filetime{uint32(n & 0xffffffff), uint32(n >> 32)}
+		}
+	}
+	return syscall.NsecToFiletime(unixTime.UnixNano())
+}
+
+func win32TimeToTar(ft syscall.Filetime) (string, time.Time) {
+	return fmt.Sprintf("%d", uint64(ft.LowDateTime)+(uint64(ft.HighDateTime)<<32)), time.Unix(0, ft.Nanoseconds())
+}
+
+// Writes a file to a tar writer using data from a Win32 backup stream.
+//
+// This encodes Win32 metadata as tar pax vendor extensions starting with MSWINDOWS.
+//
+// The additional Win32 metadata is:
+//
+// MSWINDOWS.fileattr: The Win32 file attributes, as a decimal value
+//
+// MSWINDOWS.accesstime: The last access time, as a Filetime expressed as a 64-bit decimal value.
+//
+// MSWINDOWS.createtime: The creation time, as a Filetime expressed as a 64-bit decimal value.
+//
+// MSWINDOWS.changetime: The creation time, as a Filetime expressed as a 64-bit decimal value.
+//
+// MSWINDOWS.writetime: The creation time, as a Filetime expressed as a 64-bit decimal value.
+//
+// MSWINDOWS.sd: The Win32 security descriptor, in SDDL (string) format
+//
+// MSWINDOWS.mountpoint: If present, this is a mount point and not a symlink, even though the type is '2' (symlink)
+func WriteTarFileFromBackupStream(t *tar.Writer, r io.Reader, name string, size int64, fileInfo *winio.FileBasicInfo) error {
+	name = filepath.ToSlash(name)
+	hdr := &tar.Header{
+		Name:       name,
+		Size:       size,
+		Typeflag:   tar.TypeReg,
+		Winheaders: make(map[string]string),
+	}
+	hdr.Winheaders[hdrFileAttributes] = fmt.Sprintf("%d", fileInfo.FileAttributes)
+	hdr.Winheaders[hdrAccessTime], hdr.AccessTime = win32TimeToTar(fileInfo.LastAccessTime)
+	hdr.Winheaders[hdrChangeTime], hdr.ChangeTime = win32TimeToTar(fileInfo.ChangeTime)
+	hdr.Winheaders[hdrCreateTime], _ = win32TimeToTar(fileInfo.CreationTime)
+	hdr.Winheaders[hdrWriteTime], hdr.ModTime = win32TimeToTar(fileInfo.LastWriteTime)
+
+	if (fileInfo.FileAttributes & syscall.FILE_ATTRIBUTE_DIRECTORY) != 0 {
+		hdr.Mode |= c_ISDIR
+		hdr.Size = 0
+		hdr.Typeflag = tar.TypeDir
+	}
+
+	br := winio.NewBackupStreamReader(r)
+	var dataHdr *winio.BackupHeader
+	for dataHdr == nil {
+		bhdr, err := br.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return err
+		}
+		switch bhdr.Id {
+		case winio.BackupData:
+			hdr.Mode |= c_ISREG
+			dataHdr = bhdr
+		case winio.BackupSecurity:
+			sd, err := ioutil.ReadAll(br)
+			if err != nil {
+				return err
+			}
+			sddl, err := winio.SecurityDescriptorToSddl(sd)
+			if err != nil {
+				return err
+			}
+			hdr.Winheaders[hdrSecurityDescriptor] = sddl
+
+		case winio.BackupReparseData:
+			hdr.Mode |= c_ISLNK
+			hdr.Typeflag = tar.TypeSymlink
+			reparseBuffer, err := ioutil.ReadAll(br)
+			rp, err := winio.DecodeReparsePoint(reparseBuffer)
+			if err != nil {
+				return err
+			}
+			if rp.IsMountPoint {
+				hdr.Winheaders[hdrMountPoint] = "1"
+			}
+			hdr.Linkname = rp.Target
+		case winio.BackupEaData, winio.BackupLink, winio.BackupPropertyData, winio.BackupObjectId, winio.BackupTxfsData:
+			// ignore these streams
+		default:
+			return fmt.Errorf("%s: unknown stream ID %d", name, bhdr.Id)
+		}
+	}
+
+	err := t.WriteHeader(hdr)
+	if err != nil {
+		return err
+	}
+
+	if dataHdr != nil {
+		// A data stream was found. Copy the data.
+		if (dataHdr.Attributes & winio.StreamSparseAttributes) == 0 {
+			if size != dataHdr.Size {
+				return fmt.Errorf("%s: mismatch between file size %d and header size %d", name, size, dataHdr.Size)
+			}
+			_, err = io.Copy(t, br)
+			if err != nil {
+				return err
+			}
+		} else {
+			err = copySparse(t, br)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	// Look for streams after the data stream. The only ones we handle are alternate data streams.
+	// Other streams may have metadata that could be serialized, but the tar header has already
+	// been written. In practice, this means that we don't get EA or TXF metadata.
+	for {
+		bhdr, err := br.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return err
+		}
+		switch bhdr.Id {
+		case winio.BackupAlternateData:
+			altName := bhdr.Name
+			if strings.HasSuffix(altName, ":$DATA") {
+				altName = altName[:len(altName)-len(":$DATA")]
+			}
+			if (bhdr.Attributes & winio.StreamSparseAttributes) == 0 {
+				hdr = &tar.Header{
+					Name:       name + altName,
+					Mode:       hdr.Mode,
+					Typeflag:   tar.TypeReg,
+					Size:       bhdr.Size,
+					ModTime:    hdr.ModTime,
+					AccessTime: hdr.AccessTime,
+					ChangeTime: hdr.ChangeTime,
+				}
+				err = t.WriteHeader(hdr)
+				if err != nil {
+					return err
+				}
+				_, err = io.Copy(t, br)
+				if err != nil {
+					return err
+				}
+
+			} else {
+				// Unsupported for now, since the size of the alternate stream is not present
+				// in the backup stream until after the data has been read.
+				return errors.New("tar of sparse alternate data streams is unsupported")
+			}
+		case winio.BackupEaData, winio.BackupLink, winio.BackupPropertyData, winio.BackupObjectId, winio.BackupTxfsData:
+			// ignore these streams
+		default:
+			return fmt.Errorf("%s: unknown stream ID %d after data", name, bhdr.Id)
+		}
+	}
+	return nil
+}
+
+// Retrieves basic Win32 file information from a tar header, using the additional metadata written by
+// WriteTarFileFromBackupStream.
+func FileInfoFromHeader(hdr *tar.Header) (name string, size int64, fileInfo *winio.FileBasicInfo, err error) {
+	name = hdr.Name
+	if hdr.Typeflag == tar.TypeReg || hdr.Typeflag == tar.TypeRegA {
+		size = hdr.Size
+	}
+	fileInfo = &winio.FileBasicInfo{
+		LastAccessTime: win32TimeFromTar(hdrAccessTime, hdr.Winheaders, hdr.AccessTime),
+		LastWriteTime:  win32TimeFromTar(hdrWriteTime, hdr.Winheaders, hdr.ModTime),
+		ChangeTime:     win32TimeFromTar(hdrChangeTime, hdr.Winheaders, hdr.ChangeTime),
+		CreationTime:   win32TimeFromTar(hdrCreateTime, hdr.Winheaders, hdr.ModTime),
+	}
+	if attrStr, ok := hdr.Winheaders[hdrFileAttributes]; ok {
+		attr, err := strconv.ParseUint(attrStr, 10, 32)
+		if err != nil {
+			return "", 0, nil, err
+		}
+		fileInfo.FileAttributes = uintptr(attr)
+	} else {
+		if hdr.Typeflag == tar.TypeDir {
+			fileInfo.FileAttributes |= syscall.FILE_ATTRIBUTE_DIRECTORY
+		}
+	}
+	return
+}
+
+// Writes a Win32 backup stream from the current tar file. Since this function may process multiple
+// tar file entries in order to collect all the alternate data streams for the file, it returns the next
+// tar file that was not processed, or io.EOF is there are no more.
+func WriteBackupStreamFromTarFile(w io.Writer, t *tar.Reader, hdr *tar.Header) (*tar.Header, error) {
+	bw := winio.NewBackupStreamWriter(w)
+	if sddl, ok := hdr.Winheaders[hdrSecurityDescriptor]; ok {
+		sd, err := winio.SddlToSecurityDescriptor(sddl)
+		if err != nil {
+			return nil, err
+		}
+		bhdr := winio.BackupHeader{
+			Id:   winio.BackupSecurity,
+			Size: int64(len(sd)),
+		}
+		err = bw.WriteHeader(&bhdr)
+		if err != nil {
+			return nil, err
+		}
+		_, err = bw.Write(sd)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if hdr.Typeflag == tar.TypeSymlink {
+		_, isMountPoint := hdr.Winheaders[hdrMountPoint]
+		rp := winio.ReparsePoint{
+			Target:       hdr.Linkname,
+			IsMountPoint: isMountPoint,
+		}
+		reparse := winio.EncodeReparsePoint(&rp)
+		bhdr := winio.BackupHeader{
+			Id:   winio.BackupReparseData,
+			Size: int64(len(reparse)),
+		}
+		err := bw.WriteHeader(&bhdr)
+		if err != nil {
+			return nil, err
+		}
+		_, err = bw.Write(reparse)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if hdr.Typeflag == tar.TypeReg || hdr.Typeflag == tar.TypeRegA {
+		bhdr := winio.BackupHeader{
+			Id:   winio.BackupData,
+			Size: hdr.Size,
+		}
+		err := bw.WriteHeader(&bhdr)
+		if err != nil {
+			return nil, err
+		}
+		_, err = io.Copy(bw, t)
+		if err != nil {
+			return nil, err
+		}
+	}
+	// Copy all the alternate data streams and return the next non-ADS header.
+	for {
+		ahdr, err := t.Next()
+		if err != nil {
+			return nil, err
+		}
+		if ahdr.Typeflag != tar.TypeReg || !strings.HasPrefix(ahdr.Name, hdr.Name+":") {
+			return ahdr, nil
+		}
+		bhdr := winio.BackupHeader{
+			Id:   winio.BackupAlternateData,
+			Size: ahdr.Size,
+			Name: ahdr.Name[len(hdr.Name)+1:] + ":$DATA",
+		}
+		err = bw.WriteHeader(&bhdr)
+		if err != nil {
+			return nil, err
+		}
+		_, err = io.Copy(bw, t)
+		if err != nil {
+			return nil, err
+		}
+	}
+}

vendor/github.com/Microsoft/go-winio/file.go

@@ -0,0 +1,219 @@
+package winio
+
+import (
+	"errors"
+	"io"
+	"runtime"
+	"sync"
+	"syscall"
+	"time"
+)
+
+//sys cancelIoEx(file syscall.Handle, o *syscall.Overlapped) (err error) = CancelIoEx
+//sys createIoCompletionPort(file syscall.Handle, port syscall.Handle, key uintptr, threadCount uint32) (newport syscall.Handle, err error) = CreateIoCompletionPort
+//sys getQueuedCompletionStatus(port syscall.Handle, bytes *uint32, key *uintptr, o **ioOperation, timeout uint32) (err error) = GetQueuedCompletionStatus
+//sys setFileCompletionNotificationModes(h syscall.Handle, flags uint8) (err error) = SetFileCompletionNotificationModes
+//sys timeBeginPeriod(period uint32) (n int32) = winmm.timeBeginPeriod
+
+const (
+	cFILE_SKIP_COMPLETION_PORT_ON_SUCCESS = 1
+	cFILE_SKIP_SET_EVENT_ON_HANDLE        = 2
+)
+
+var (
+	ErrFileClosed = errors.New("file has already been closed")
+	ErrTimeout    = &timeoutError{}
+)
+
+type timeoutError struct{}
+
+func (e *timeoutError) Error() string   { return "i/o timeout" }
+func (e *timeoutError) Timeout() bool   { return true }
+func (e *timeoutError) Temporary() bool { return true }
+
+var ioInitOnce sync.Once
+var ioCompletionPort syscall.Handle
+
+// ioResult contains the result of an asynchronous IO operation
+type ioResult struct {
+	bytes uint32
+	err   error
+}
+
+// ioOperation represents an outstanding asynchronous Win32 IO
+type ioOperation struct {
+	o  syscall.Overlapped
+	ch chan ioResult
+}
+
+func initIo() {
+	h, err := createIoCompletionPort(syscall.InvalidHandle, 0, 0, 0xffffffff)
+	if err != nil {
+		panic(err)
+	}
+	ioCompletionPort = h
+	go ioCompletionProcessor(h)
+}
+
+// win32File implements Reader, Writer, and Closer on a Win32 handle without blocking in a syscall.
+// It takes ownership of this handle and will close it if it is garbage collected.
+type win32File struct {
+	handle        syscall.Handle
+	wg            sync.WaitGroup
+	closing       bool
+	readDeadline  time.Time
+	writeDeadline time.Time
+}
+
+// makeWin32File makes a new win32File from an existing file handle
+func makeWin32File(h syscall.Handle) (*win32File, error) {
+	f := &win32File{handle: h}
+	ioInitOnce.Do(initIo)
+	_, err := createIoCompletionPort(h, ioCompletionPort, 0, 0xffffffff)
+	if err != nil {
+		return nil, err
+	}
+	err = setFileCompletionNotificationModes(h, cFILE_SKIP_COMPLETION_PORT_ON_SUCCESS|cFILE_SKIP_SET_EVENT_ON_HANDLE)
+	if err != nil {
+		return nil, err
+	}
+	runtime.SetFinalizer(f, (*win32File).closeHandle)
+	return f, nil
+}
+
+func MakeOpenFile(h syscall.Handle) (io.ReadWriteCloser, error) {
+	return makeWin32File(h)
+}
+
+// closeHandle closes the resources associated with a Win32 handle
+func (f *win32File) closeHandle() {
+	if !f.closing {
+		// cancel all IO and wait for it to complete
+		f.closing = true
+		cancelIoEx(f.handle, nil)
+		f.wg.Wait()
+		// at this point, no new IO can start
+		syscall.Close(f.handle)
+		f.handle = 0
+	}
+}
+
+// Close closes a win32File.
+func (f *win32File) Close() error {
+	f.closeHandle()
+	runtime.SetFinalizer(f, nil)
+	return nil
+}
+
+// prepareIo prepares for a new IO operation
+func (f *win32File) prepareIo() (*ioOperation, error) {
+	f.wg.Add(1)
+	if f.closing {
+		return nil, ErrFileClosed
+	}
+	c := &ioOperation{}
+	c.ch = make(chan ioResult)
+	return c, nil
+}
+
+// ioCompletionProcessor processes completed async IOs forever
+func ioCompletionProcessor(h syscall.Handle) {
+	// Set the timer resolution to 1. This fixes a performance regression in golang 1.6.
+	timeBeginPeriod(1)
+	for {
+		var bytes uint32
+		var key uintptr
+		var op *ioOperation
+		err := getQueuedCompletionStatus(h, &bytes, &key, &op, syscall.INFINITE)
+		if op == nil {
+			panic(err)
+		}
+		op.ch <- ioResult{bytes, err}
+	}
+}
+
+// asyncIo processes the return value from ReadFile or WriteFile, blocking until
+// the operation has actually completed.
+func (f *win32File) asyncIo(c *ioOperation, deadline time.Time, bytes uint32, err error) (int, error) {
+	if err != syscall.ERROR_IO_PENDING {
+		f.wg.Done()
+		return int(bytes), err
+	} else {
+		var r ioResult
+		wait := true
+		timedout := false
+		if f.closing {
+			cancelIoEx(f.handle, &c.o)
+		} else if !deadline.IsZero() {
+			now := time.Now()
+			if !deadline.After(now) {
+				timedout = true
+			} else {
+				timeout := time.After(deadline.Sub(now))
+				select {
+				case r = <-c.ch:
+					wait = false
+				case <-timeout:
+					timedout = true
+				}
+			}
+		}
+		if timedout {
+			cancelIoEx(f.handle, &c.o)
+		}
+		if wait {
+			r = <-c.ch
+		}
+		err = r.err
+		if err == syscall.ERROR_OPERATION_ABORTED {
+			if f.closing {
+				err = ErrFileClosed
+			} else if timedout {
+				err = ErrTimeout
+			}
+		}
+		f.wg.Done()
+		return int(r.bytes), err
+	}
+}
+
+// Read reads from a file handle.
+func (f *win32File) Read(b []byte) (int, error) {
+	c, err := f.prepareIo()
+	if err != nil {
+		return 0, err
+	}
+	var bytes uint32
+	err = syscall.ReadFile(f.handle, b, &bytes, &c.o)
+	n, err := f.asyncIo(c, f.readDeadline, bytes, err)
+
+	// Handle EOF conditions.
+	if err == nil && n == 0 && len(b) != 0 {
+		return 0, io.EOF
+	} else if err == syscall.ERROR_BROKEN_PIPE {
+		return 0, io.EOF
+	} else {
+		return n, err
+	}
+}
+
+// Write writes to a file handle.
+func (f *win32File) Write(b []byte) (int, error) {
+	c, err := f.prepareIo()
+	if err != nil {
+		return 0, err
+	}
+	var bytes uint32
+	err = syscall.WriteFile(f.handle, b, &bytes, &c.o)
+	return f.asyncIo(c, f.writeDeadline, bytes, err)
+}
+
+func (f *win32File) SetReadDeadline(t time.Time) error {
+	f.readDeadline = t
+	return nil
+}
+
+func (f *win32File) SetWriteDeadline(t time.Time) error {
+	f.writeDeadline = t
+	return nil
+}

vendor/github.com/Microsoft/go-winio/fileinfo.go

@@ -0,0 +1,30 @@
+package winio
+
+import (
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+//sys getFileInformationByHandleEx(h syscall.Handle, class uint32, buffer *byte, size uint32) (err error) = GetFileInformationByHandleEx
+//sys setFileInformationByHandle(h syscall.Handle, class uint32, buffer *byte, size uint32) (err error) = SetFileInformationByHandle
+
+type FileBasicInfo struct {
+	CreationTime, LastAccessTime, LastWriteTime, ChangeTime syscall.Filetime
+	FileAttributes                                          uintptr // includes padding
+}
+
+func GetFileBasicInfo(f *os.File) (*FileBasicInfo, error) {
+	bi := &FileBasicInfo{}
+	if err := getFileInformationByHandleEx(syscall.Handle(f.Fd()), 0, (*byte)(unsafe.Pointer(bi)), uint32(unsafe.Sizeof(*bi))); err != nil {
+		return nil, &os.PathError{"GetFileInformationByHandleEx", f.Name(), err}
+	}
+	return bi, nil
+}
+
+func SetFileBasicInfo(f *os.File, bi *FileBasicInfo) error {
+	if err := setFileInformationByHandle(syscall.Handle(f.Fd()), 0, (*byte)(unsafe.Pointer(bi)), uint32(unsafe.Sizeof(*bi))); err != nil {
+		return &os.PathError{"SetFileInformationByHandle", f.Name(), err}
+	}
+	return nil
+}

vendor/github.com/Microsoft/go-winio/pipe.go

@@ -0,0 +1,398 @@
+package winio
+
+import (
+	"errors"
+	"io"
+	"net"
+	"os"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+//sys connectNamedPipe(pipe syscall.Handle, o *syscall.Overlapped) (err error) = ConnectNamedPipe
+//sys createNamedPipe(name string, flags uint32, pipeMode uint32, maxInstances uint32, outSize uint32, inSize uint32, defaultTimeout uint32, sa *securityAttributes) (handle syscall.Handle, err error)  [failretval==syscall.InvalidHandle] = CreateNamedPipeW
+//sys createFile(name string, access uint32, mode uint32, sa *securityAttributes, createmode uint32, attrs uint32, templatefile syscall.Handle) (handle syscall.Handle, err error) [failretval==syscall.InvalidHandle] = CreateFileW
+//sys waitNamedPipe(name string, timeout uint32) (err error) = WaitNamedPipeW
+//sys getNamedPipeInfo(pipe syscall.Handle, flags *uint32, outSize *uint32, inSize *uint32, maxInstances *uint32) (err error) = GetNamedPipeInfo
+//sys getNamedPipeHandleState(pipe syscall.Handle, state *uint32, curInstances *uint32, maxCollectionCount *uint32, collectDataTimeout *uint32, userName *uint16, maxUserNameSize uint32) (err error) = GetNamedPipeHandleStateW
+
+type securityAttributes struct {
+	Length             uint32
+	SecurityDescriptor *byte
+	InheritHandle      uint32
+}
+
+const (
+	cERROR_PIPE_BUSY      = syscall.Errno(231)
+	cERROR_PIPE_CONNECTED = syscall.Errno(535)
+	cERROR_SEM_TIMEOUT    = syscall.Errno(121)
+
+	cPIPE_ACCESS_DUPLEX            = 0x3
+	cFILE_FLAG_FIRST_PIPE_INSTANCE = 0x80000
+	cSECURITY_SQOS_PRESENT         = 0x100000
+	cSECURITY_ANONYMOUS            = 0
+
+	cPIPE_REJECT_REMOTE_CLIENTS = 0x8
+
+	cPIPE_UNLIMITED_INSTANCES = 255
+
+	cNMPWAIT_USE_DEFAULT_WAIT = 0
+	cNMPWAIT_NOWAIT           = 1
+
+	cPIPE_TYPE_MESSAGE = 4
+
+	cPIPE_READMODE_MESSAGE = 2
+)
+
+var (
+	// ErrPipeListenerClosed is returned for pipe operations on listeners that have been closed.
+	// This error should match net.errClosing since docker takes a dependency on its text.
+	ErrPipeListenerClosed = errors.New("use of closed network connection")
+
+	errPipeWriteClosed = errors.New("pipe has been closed for write")
+)
+
+type win32Pipe struct {
+	*win32File
+	path string
+}
+
+type win32MessageBytePipe struct {
+	win32Pipe
+	writeClosed bool
+	readEOF     bool
+}
+
+type pipeAddress string
+
+func (f *win32Pipe) LocalAddr() net.Addr {
+	return pipeAddress(f.path)
+}
+
+func (f *win32Pipe) RemoteAddr() net.Addr {
+	return pipeAddress(f.path)
+}
+
+func (f *win32Pipe) SetDeadline(t time.Time) error {
+	f.SetReadDeadline(t)
+	f.SetWriteDeadline(t)
+	return nil
+}
+
+// CloseWrite closes the write side of a message pipe in byte mode.
+func (f *win32MessageBytePipe) CloseWrite() error {
+	if f.writeClosed {
+		return errPipeWriteClosed
+	}
+	_, err := f.win32File.Write(nil)
+	if err != nil {
+		return err
+	}
+	f.writeClosed = true
+	return nil
+}
+
+// Write writes bytes to a message pipe in byte mode. Zero-byte writes are ignored, since
+// they are used to implement CloseWrite().
+func (f *win32MessageBytePipe) Write(b []byte) (int, error) {
+	if f.writeClosed {
+		return 0, errPipeWriteClosed
+	}
+	if len(b) == 0 {
+		return 0, nil
+	}
+	return f.win32File.Write(b)
+}
+
+// Read reads bytes from a message pipe in byte mode. A read of a zero-byte message on a message
+// mode pipe will return io.EOF, as will all subsequent reads.
+func (f *win32MessageBytePipe) Read(b []byte) (int, error) {
+	if f.readEOF {
+		return 0, io.EOF
+	}
+	n, err := f.win32File.Read(b)
+	if err == io.EOF {
+		// If this was the result of a zero-byte read, then
+		// it is possible that the read was due to a zero-size
+		// message. Since we are simulating CloseWrite with a
+		// zero-byte message, ensure that all future Read() calls
+		// also return EOF.
+		f.readEOF = true
+	}
+	return n, err
+}
+
+func (s pipeAddress) Network() string {
+	return "pipe"
+}
+
+func (s pipeAddress) String() string {
+	return string(s)
+}
+
+// DialPipe connects to a named pipe by path, timing out if the connection
+// takes longer than the specified duration. If timeout is nil, then the timeout
+// is the default timeout established by the pipe server.
+func DialPipe(path string, timeout *time.Duration) (net.Conn, error) {
+	var absTimeout time.Time
+	if timeout != nil {
+		absTimeout = time.Now().Add(*timeout)
+	}
+	var err error
+	var h syscall.Handle
+	for {
+		h, err = createFile(path, syscall.GENERIC_READ|syscall.GENERIC_WRITE, 0, nil, syscall.OPEN_EXISTING, syscall.FILE_FLAG_OVERLAPPED|cSECURITY_SQOS_PRESENT|cSECURITY_ANONYMOUS, 0)
+		if err != cERROR_PIPE_BUSY {
+			break
+		}
+		now := time.Now()
+		var ms uint32
+		if absTimeout.IsZero() {
+			ms = cNMPWAIT_USE_DEFAULT_WAIT
+		} else if now.After(absTimeout) {
+			ms = cNMPWAIT_NOWAIT
+		} else {
+			ms = uint32(absTimeout.Sub(now).Nanoseconds() / 1000 / 1000)
+		}
+		err = waitNamedPipe(path, ms)
+		if err != nil {
+			if err == cERROR_SEM_TIMEOUT {
+				return nil, ErrTimeout
+			}
+			break
+		}
+	}
+	if err != nil {
+		return nil, &os.PathError{Op: "open", Path: path, Err: err}
+	}
+
+	var flags uint32
+	err = getNamedPipeInfo(h, &flags, nil, nil, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	var state uint32
+	err = getNamedPipeHandleState(h, &state, nil, nil, nil, nil, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	if state&cPIPE_READMODE_MESSAGE != 0 {
+		return nil, &os.PathError{Op: "open", Path: path, Err: errors.New("message readmode pipes not supported")}
+	}
+
+	f, err := makeWin32File(h)
+	if err != nil {
+		syscall.Close(h)
+		return nil, err
+	}
+
+	// If the pipe is in message mode, return a message byte pipe, which
+	// supports CloseWrite().
+	if flags&cPIPE_TYPE_MESSAGE != 0 {
+		return &win32MessageBytePipe{
+			win32Pipe: win32Pipe{win32File: f, path: path},
+		}, nil
+	}
+	return &win32Pipe{win32File: f, path: path}, nil
+}
+
+type acceptResponse struct {
+	f   *win32File
+	err error
+}
+
+type win32PipeListener struct {
+	firstHandle        syscall.Handle
+	path               string
+	securityDescriptor []byte
+	config             PipeConfig
+	acceptCh           chan (chan acceptResponse)
+	closeCh            chan int
+	doneCh             chan int
+}
+
+func makeServerPipeHandle(path string, securityDescriptor []byte, c *PipeConfig, first bool) (syscall.Handle, error) {
+	var flags uint32 = cPIPE_ACCESS_DUPLEX | syscall.FILE_FLAG_OVERLAPPED
+	if first {
+		flags |= cFILE_FLAG_FIRST_PIPE_INSTANCE
+	}
+
+	var mode uint32 = cPIPE_REJECT_REMOTE_CLIENTS
+	if c.MessageMode {
+		mode |= cPIPE_TYPE_MESSAGE
+	}
+
+	var sa securityAttributes
+	sa.Length = uint32(unsafe.Sizeof(sa))
+	if securityDescriptor != nil {
+		sa.SecurityDescriptor = &securityDescriptor[0]
+	}
+	h, err := createNamedPipe(path, flags, mode, cPIPE_UNLIMITED_INSTANCES, uint32(c.OutputBufferSize), uint32(c.InputBufferSize), 0, &sa)
+	if err != nil {
+		return 0, &os.PathError{Op: "open", Path: path, Err: err}
+	}
+	return h, nil
+}
+
+func (l *win32PipeListener) makeServerPipe() (*win32File, error) {
+	h, err := makeServerPipeHandle(l.path, l.securityDescriptor, &l.config, false)
+	if err != nil {
+		return nil, err
+	}
+	f, err := makeWin32File(h)
+	if err != nil {
+		syscall.Close(h)
+		return nil, err
+	}
+	return f, nil
+}
+
+func (l *win32PipeListener) listenerRoutine() {
+	closed := false
+	for !closed {
+		select {
+		case <-l.closeCh:
+			closed = true
+		case responseCh := <-l.acceptCh:
+			p, err := l.makeServerPipe()
+			if err == nil {
+				// Wait for the client to connect.
+				ch := make(chan error)
+				go func() {
+					ch <- connectPipe(p)
+				}()
+				select {
+				case err = <-ch:
+					if err != nil {
+						p.Close()
+						p = nil
+					}
+				case <-l.closeCh:
+					// Abort the connect request by closing the handle.
+					p.Close()
+					p = nil
+					err = <-ch
+					if err == nil || err == ErrFileClosed {
+						err = ErrPipeListenerClosed
+					}
+					closed = true
+				}
+			}
+			responseCh <- acceptResponse{p, err}
+		}
+	}
+	syscall.Close(l.firstHandle)
+	l.firstHandle = 0
+	// Notify Close() and Accept() callers that the handle has been closed.
+	close(l.doneCh)
+}
+
+// PipeConfig contain configuration for the pipe listener.
+type PipeConfig struct {
+	// SecurityDescriptor contains a Windows security descriptor in SDDL format.
+	SecurityDescriptor string
+
+	// MessageMode determines whether the pipe is in byte or message mode. In either
+	// case the pipe is read in byte mode by default. The only practical difference in
+	// this implementation is that CloseWrite() is only supported for message mode pipes;
+	// CloseWrite() is implemented as a zero-byte write, but zero-byte writes are only
+	// transferred to the reader (and returned as io.EOF in this implementation)
+	// when the pipe is in message mode.
+	MessageMode bool
+
+	// InputBufferSize specifies the size the input buffer, in bytes.
+	InputBufferSize int32
+
+	// OutputBufferSize specifies the size the input buffer, in bytes.
+	OutputBufferSize int32
+}
+
+// ListenPipe creates a listener on a Windows named pipe path, e.g. \\.\pipe\mypipe.
+// The pipe must not already exist.
+func ListenPipe(path string, c *PipeConfig) (net.Listener, error) {
+	var (
+		sd  []byte
+		err error
+	)
+	if c == nil {
+		c = &PipeConfig{}
+	}
+	if c.SecurityDescriptor != "" {
+		sd, err = SddlToSecurityDescriptor(c.SecurityDescriptor)
+		if err != nil {
+			return nil, err
+		}
+	}
+	h, err := makeServerPipeHandle(path, sd, c, true)
+	if err != nil {
+		return nil, err
+	}
+	// Immediately open and then close a client handle so that the named pipe is
+	// created but not currently accepting connections.
+	h2, err := createFile(path, 0, 0, nil, syscall.OPEN_EXISTING, cSECURITY_SQOS_PRESENT|cSECURITY_ANONYMOUS, 0)
+	if err != nil {
+		syscall.Close(h)
+		return nil, err
+	}
+	syscall.Close(h2)
+	l := &win32PipeListener{
+		firstHandle:        h,
+		path:               path,
+		securityDescriptor: sd,
+		config:             *c,
+		acceptCh:           make(chan (chan acceptResponse)),
+		closeCh:            make(chan int),
+		doneCh:             make(chan int),
+	}
+	go l.listenerRoutine()
+	return l, nil
+}
+
+func connectPipe(p *win32File) error {
+	c, err := p.prepareIo()
+	if err != nil {
+		return err
+	}
+	err = connectNamedPipe(p.handle, &c.o)
+	_, err = p.asyncIo(c, time.Time{}, 0, err)
+	if err != nil && err != cERROR_PIPE_CONNECTED {
+		return err
+	}
+	return nil
+}
+
+func (l *win32PipeListener) Accept() (net.Conn, error) {
+	ch := make(chan acceptResponse)
+	select {
+	case l.acceptCh <- ch:
+		response := <-ch
+		err := response.err
+		if err != nil {
+			return nil, err
+		}
+		if l.config.MessageMode {
+			return &win32MessageBytePipe{
+				win32Pipe: win32Pipe{win32File: response.f, path: l.path},
+			}, nil
+		}
+		return &win32Pipe{win32File: response.f, path: l.path}, nil
+	case <-l.doneCh:
+		return nil, ErrPipeListenerClosed
+	}
+}
+
+func (l *win32PipeListener) Close() error {
+	select {
+	case l.closeCh <- 1:
+		<-l.doneCh
+	case <-l.doneCh:
+	}
+	return nil
+}
+
+func (l *win32PipeListener) Addr() net.Addr {
+	return pipeAddress(l.path)
+}

vendor/github.com/Microsoft/go-winio/privilege.go

@@ -0,0 +1,150 @@
+package winio
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"runtime"
+	"syscall"
+	"unicode/utf16"
+)
+
+//sys adjustTokenPrivileges(token syscall.Handle, releaseAll bool, input *byte, outputSize uint32, output *byte, requiredSize *uint32) (success bool, err error) [true] = advapi32.AdjustTokenPrivileges
+//sys impersonateSelf(level uint32) (err error) = advapi32.ImpersonateSelf
+//sys revertToSelf() (err error) = advapi32.RevertToSelf
+//sys openThreadToken(thread syscall.Handle, accessMask uint32, openAsSelf bool, token *syscall.Handle) (err error) = advapi32.OpenThreadToken
+//sys getCurrentThread() (h syscall.Handle) = GetCurrentThread
+//sys lookupPrivilegeValue(systemName string, name string, luid *uint64) (err error) = advapi32.LookupPrivilegeValueW
+//sys lookupPrivilegeName(systemName string, luid *uint64, buffer *uint16, size *uint32) (err error) = advapi32.LookupPrivilegeNameW
+//sys lookupPrivilegeDisplayName(systemName string, name *uint16, buffer *uint16, size *uint32, languageId *uint32) (err error) = advapi32.LookupPrivilegeDisplayNameW
+
+const (
+	SE_PRIVILEGE_ENABLED = 2
+
+	ERROR_NOT_ALL_ASSIGNED syscall.Errno = 1300
+
+	SeBackupPrivilege  = "SeBackupPrivilege"
+	SeRestorePrivilege = "SeRestorePrivilege"
+)
+
+const (
+	securityAnonymous = iota
+	securityIdentification
+	securityImpersonation
+	securityDelegation
+)
+
+type PrivilegeError struct {
+	privileges []uint64
+}
+
+func (e *PrivilegeError) Error() string {
+	s := ""
+	if len(e.privileges) > 1 {
+		s = "Could not enable privileges "
+	} else {
+		s = "Could not enable privilege "
+	}
+	for i, p := range e.privileges {
+		if i != 0 {
+			s += ", "
+		}
+		s += `"`
+		s += getPrivilegeName(p)
+		s += `"`
+	}
+	return s
+}
+
+func RunWithPrivilege(name string, fn func() error) error {
+	return RunWithPrivileges([]string{name}, fn)
+}
+
+func RunWithPrivileges(names []string, fn func() error) error {
+	var privileges []uint64
+	for _, name := range names {
+		p := uint64(0)
+		err := lookupPrivilegeValue("", name, &p)
+		if err != nil {
+			return err
+		}
+		privileges = append(privileges, p)
+	}
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+	token, err := newThreadToken()
+	if err != nil {
+		return err
+	}
+	defer releaseThreadToken(token)
+	err = adjustPrivileges(token, privileges)
+	if err != nil {
+		return err
+	}
+	return fn()
+}
+
+func adjustPrivileges(token syscall.Handle, privileges []uint64) error {
+	var b bytes.Buffer
+	binary.Write(&b, binary.LittleEndian, uint32(len(privileges)))
+	for _, p := range privileges {
+		binary.Write(&b, binary.LittleEndian, p)
+		binary.Write(&b, binary.LittleEndian, uint32(SE_PRIVILEGE_ENABLED))
+	}
+	prevState := make([]byte, b.Len())
+	reqSize := uint32(0)
+	success, err := adjustTokenPrivileges(token, false, &b.Bytes()[0], uint32(len(prevState)), &prevState[0], &reqSize)
+	if !success {
+		return err
+	}
+	if err == ERROR_NOT_ALL_ASSIGNED {
+		return &PrivilegeError{privileges}
+	}
+	return nil
+}
+
+func getPrivilegeName(luid uint64) string {
+	var nameBuffer [256]uint16
+	bufSize := uint32(len(nameBuffer))
+	err := lookupPrivilegeName("", &luid, &nameBuffer[0], &bufSize)
+	if err != nil {
+		return fmt.Sprintf("<unknown privilege %d>", luid)
+	}
+
+	var displayNameBuffer [256]uint16
+	displayBufSize := uint32(len(displayNameBuffer))
+	var langId uint32
+	err = lookupPrivilegeDisplayName("", &nameBuffer[0], &displayNameBuffer[0], &displayBufSize, &langId)
+	if err != nil {
+		return fmt.Sprintf("<unknown privilege %s>", utf16.Decode(nameBuffer[:bufSize]))
+	}
+
+	return string(utf16.Decode(displayNameBuffer[:displayBufSize]))
+}
+
+func newThreadToken() (syscall.Handle, error) {
+	err := impersonateSelf(securityImpersonation)
+	if err != nil {
+		panic(err)
+		return 0, err
+	}
+
+	var token syscall.Handle
+	err = openThreadToken(getCurrentThread(), syscall.TOKEN_ADJUST_PRIVILEGES|syscall.TOKEN_QUERY, false, &token)
+	if err != nil {
+		rerr := revertToSelf()
+		if rerr != nil {
+			panic(rerr)
+		}
+		return 0, err
+	}
+	return token, nil
+}
+
+func releaseThreadToken(h syscall.Handle) {
+	err := revertToSelf()
+	if err != nil {
+		panic(err)
+	}
+	syscall.Close(h)
+}

vendor/github.com/Microsoft/go-winio/reparse.go

@@ -0,0 +1,124 @@
+package winio
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"strings"
+	"unicode/utf16"
+	"unsafe"
+)
+
+const (
+	reparseTagMountPoint = 0xA0000003
+	reparseTagSymlink    = 0xA000000C
+)
+
+type reparseDataBuffer struct {
+	ReparseTag           uint32
+	ReparseDataLength    uint16
+	Reserved             uint16
+	SubstituteNameOffset uint16
+	SubstituteNameLength uint16
+	PrintNameOffset      uint16
+	PrintNameLength      uint16
+}
+
+// ReparsePoint describes a Win32 symlink or mount point.
+type ReparsePoint struct {
+	Target       string
+	IsMountPoint bool
+}
+
+// UnsupportedReparsePointError is returned when trying to decode a non-symlink or
+// mount point reparse point.
+type UnsupportedReparsePointError struct {
+	Tag uint32
+}
+
+func (e *UnsupportedReparsePointError) Error() string {
+	return fmt.Sprintf("unsupported reparse point %x", e.Tag)
+}
+
+// DecodeReparsePoint decodes a Win32 REPARSE_DATA_BUFFER structure containing either a symlink
+// or a mount point.
+func DecodeReparsePoint(b []byte) (*ReparsePoint, error) {
+	isMountPoint := false
+	tag := binary.LittleEndian.Uint32(b[0:4])
+	switch tag {
+	case reparseTagMountPoint:
+		isMountPoint = true
+	case reparseTagSymlink:
+	default:
+		return nil, &UnsupportedReparsePointError{tag}
+	}
+	nameOffset := 16 + binary.LittleEndian.Uint16(b[12:14])
+	if !isMountPoint {
+		nameOffset += 4
+	}
+	nameLength := binary.LittleEndian.Uint16(b[14:16])
+	name := make([]uint16, nameLength/2)
+	err := binary.Read(bytes.NewReader(b[nameOffset:nameOffset+nameLength]), binary.LittleEndian, &name)
+	if err != nil {
+		return nil, err
+	}
+	return &ReparsePoint{string(utf16.Decode(name)), isMountPoint}, nil
+}
+
+func isDriveLetter(c byte) bool {
+	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
+}
+
+// EncodeReparsePoint encodes a Win32 REPARSE_DATA_BUFFER structure describing a symlink or
+// mount point.
+func EncodeReparsePoint(rp *ReparsePoint) []byte {
+	// Generate an NT path and determine if this is a relative path.
+	var ntTarget string
+	relative := false
+	if strings.HasPrefix(rp.Target, `\\?\`) {
+		ntTarget = rp.Target
+	} else if strings.HasPrefix(rp.Target, `\\`) {
+		ntTarget = `\??\UNC\` + rp.Target[2:]
+	} else if len(rp.Target) >= 2 && isDriveLetter(rp.Target[0]) && rp.Target[1] == ':' {
+		ntTarget = `\??\` + rp.Target
+	} else {
+		ntTarget = rp.Target
+		relative = true
+	}
+
+	// The paths must be NUL-terminated even though they are counted strings.
+	target16 := utf16.Encode([]rune(rp.Target + "\x00"))
+	ntTarget16 := utf16.Encode([]rune(ntTarget + "\x00"))
+
+	size := int(unsafe.Sizeof(reparseDataBuffer{})) - 8
+	size += len(ntTarget16)*2 + len(target16)*2
+
+	tag := uint32(reparseTagMountPoint)
+	if !rp.IsMountPoint {
+		tag = reparseTagSymlink
+		size += 4 // Add room for symlink flags
+	}
+
+	data := reparseDataBuffer{
+		ReparseTag:           tag,
+		ReparseDataLength:    uint16(size),
+		SubstituteNameOffset: 0,
+		SubstituteNameLength: uint16((len(ntTarget16) - 1) * 2),
+		PrintNameOffset:      uint16(len(ntTarget16) * 2),
+		PrintNameLength:      uint16((len(target16) - 1) * 2),
+	}
+
+	var b bytes.Buffer
+	binary.Write(&b, binary.LittleEndian, &data)
+	if !rp.IsMountPoint {
+		flags := uint32(0)
+		if relative {
+			flags |= 1
+		}
+		binary.Write(&b, binary.LittleEndian, flags)
+	}
+
+	binary.Write(&b, binary.LittleEndian, ntTarget16)
+	binary.Write(&b, binary.LittleEndian, target16)
+	return b.Bytes()
+}

vendor/github.com/Microsoft/go-winio/sd.go

@@ -0,0 +1,96 @@
+package winio
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+//sys lookupAccountName(systemName *uint16, accountName string, sid *byte, sidSize *uint32, refDomain *uint16, refDomainSize *uint32, sidNameUse *uint32) (err error) = advapi32.LookupAccountNameW
+//sys convertSidToStringSid(sid *byte, str **uint16) (err error) = advapi32.ConvertSidToStringSidW
+//sys convertStringSecurityDescriptorToSecurityDescriptor(str string, revision uint32, sd *uintptr, size *uint32) (err error) = advapi32.ConvertStringSecurityDescriptorToSecurityDescriptorW
+//sys convertSecurityDescriptorToStringSecurityDescriptor(sd *byte, revision uint32, secInfo uint32, sddl **uint16, sddlSize *uint32) (err error) = advapi32.ConvertSecurityDescriptorToStringSecurityDescriptorW
+//sys localFree(mem uintptr) = LocalFree
+//sys getSecurityDescriptorLength(sd uintptr) (len uint32) = advapi32.GetSecurityDescriptorLength
+
+const (
+	cERROR_NONE_MAPPED = syscall.Errno(1332)
+)
+
+type AccountLookupError struct {
+	Name string
+	Err  error
+}
+
+func (e *AccountLookupError) Error() string {
+	if e.Name == "" {
+		return "lookup account: empty account name specified"
+	}
+	var s string
+	switch e.Err {
+	case cERROR_NONE_MAPPED:
+		s = "not found"
+	default:
+		s = e.Err.Error()
+	}
+	return "lookup account " + e.Name + ": " + s
+}
+
+type SddlConversionError struct {
+	Sddl string
+	Err  error
+}
+
+func (e *SddlConversionError) Error() string {
+	return "convert " + e.Sddl + ": " + e.Err.Error()
+}
+
+// LookupSidByName looks up the SID of an account by name
+func LookupSidByName(name string) (sid string, err error) {
+	if name == "" {
+		return "", &AccountLookupError{name, cERROR_NONE_MAPPED}
+	}
+
+	var sidSize, sidNameUse, refDomainSize uint32
+	err = lookupAccountName(nil, name, nil, &sidSize, nil, &refDomainSize, &sidNameUse)
+	if err != nil && err != syscall.ERROR_INSUFFICIENT_BUFFER {
+		return "", &AccountLookupError{name, err}
+	}
+	sidBuffer := make([]byte, sidSize)
+	refDomainBuffer := make([]uint16, refDomainSize)
+	err = lookupAccountName(nil, name, &sidBuffer[0], &sidSize, &refDomainBuffer[0], &refDomainSize, &sidNameUse)
+	if err != nil {
+		return "", &AccountLookupError{name, err}
+	}
+	var strBuffer *uint16
+	err = convertSidToStringSid(&sidBuffer[0], &strBuffer)
+	if err != nil {
+		return "", &AccountLookupError{name, err}
+	}
+	sid = syscall.UTF16ToString((*[0xffff]uint16)(unsafe.Pointer(strBuffer))[:])
+	localFree(uintptr(unsafe.Pointer(strBuffer)))
+	return sid, nil
+}
+
+func SddlToSecurityDescriptor(sddl string) ([]byte, error) {
+	var sdBuffer uintptr
+	err := convertStringSecurityDescriptorToSecurityDescriptor(sddl, 1, &sdBuffer, nil)
+	if err != nil {
+		return nil, &SddlConversionError{sddl, err}
+	}
+	defer localFree(sdBuffer)
+	sd := make([]byte, getSecurityDescriptorLength(sdBuffer))
+	copy(sd, (*[0xffff]byte)(unsafe.Pointer(sdBuffer))[:len(sd)])
+	return sd, nil
+}
+
+func SecurityDescriptorToSddl(sd []byte) (string, error) {
+	var sddl *uint16
+	// The returned string length seems to including an aribtrary number of terminating NULs.
+	// Don't use it.
+	err := convertSecurityDescriptorToStringSecurityDescriptor(&sd[0], 1, 0xff, &sddl, nil)
+	if err != nil {
+		return "", err
+	}
+	defer localFree(uintptr(unsafe.Pointer(sddl)))
+	return syscall.UTF16ToString((*[0xffff]uint16)(unsafe.Pointer(sddl))[:]), nil
+}

vendor/github.com/Microsoft/go-winio/syscall.go

@@ -0,0 +1,3 @@
+package winio
+
+//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall.go file.go pipe.go sd.go fileinfo.go privilege.go backup.go

vendor/github.com/Microsoft/go-winio/zsyscall.go

@@ -0,0 +1,492 @@
+// MACHINE GENERATED BY 'go generate' COMMAND; DO NOT EDIT
+
+package winio
+
+import "unsafe"
+import "syscall"
+
+var _ unsafe.Pointer
+
+var (
+	modkernel32 = syscall.NewLazyDLL("kernel32.dll")
+	modwinmm    = syscall.NewLazyDLL("winmm.dll")
+	modadvapi32 = syscall.NewLazyDLL("advapi32.dll")
+
+	procCancelIoEx                                           = modkernel32.NewProc("CancelIoEx")
+	procCreateIoCompletionPort                               = modkernel32.NewProc("CreateIoCompletionPort")
+	procGetQueuedCompletionStatus                            = modkernel32.NewProc("GetQueuedCompletionStatus")
+	procSetFileCompletionNotificationModes                   = modkernel32.NewProc("SetFileCompletionNotificationModes")
+	proctimeBeginPeriod                                      = modwinmm.NewProc("timeBeginPeriod")
+	procConnectNamedPipe                                     = modkernel32.NewProc("ConnectNamedPipe")
+	procCreateNamedPipeW                                     = modkernel32.NewProc("CreateNamedPipeW")
+	procCreateFileW                                          = modkernel32.NewProc("CreateFileW")
+	procWaitNamedPipeW                                       = modkernel32.NewProc("WaitNamedPipeW")
+	procGetNamedPipeInfo                                     = modkernel32.NewProc("GetNamedPipeInfo")
+	procGetNamedPipeHandleStateW                             = modkernel32.NewProc("GetNamedPipeHandleStateW")
+	procLookupAccountNameW                                   = modadvapi32.NewProc("LookupAccountNameW")
+	procConvertSidToStringSidW                               = modadvapi32.NewProc("ConvertSidToStringSidW")
+	procConvertStringSecurityDescriptorToSecurityDescriptorW = modadvapi32.NewProc("ConvertStringSecurityDescriptorToSecurityDescriptorW")
+	procConvertSecurityDescriptorToStringSecurityDescriptorW = modadvapi32.NewProc("ConvertSecurityDescriptorToStringSecurityDescriptorW")
+	procLocalFree                                            = modkernel32.NewProc("LocalFree")
+	procGetSecurityDescriptorLength                          = modadvapi32.NewProc("GetSecurityDescriptorLength")
+	procGetFileInformationByHandleEx                         = modkernel32.NewProc("GetFileInformationByHandleEx")
+	procSetFileInformationByHandle                           = modkernel32.NewProc("SetFileInformationByHandle")
+	procAdjustTokenPrivileges                                = modadvapi32.NewProc("AdjustTokenPrivileges")
+	procImpersonateSelf                                      = modadvapi32.NewProc("ImpersonateSelf")
+	procRevertToSelf                                         = modadvapi32.NewProc("RevertToSelf")
+	procOpenThreadToken                                      = modadvapi32.NewProc("OpenThreadToken")
+	procGetCurrentThread                                     = modkernel32.NewProc("GetCurrentThread")
+	procLookupPrivilegeValueW                                = modadvapi32.NewProc("LookupPrivilegeValueW")
+	procLookupPrivilegeNameW                                 = modadvapi32.NewProc("LookupPrivilegeNameW")
+	procLookupPrivilegeDisplayNameW                          = modadvapi32.NewProc("LookupPrivilegeDisplayNameW")
+	procBackupRead                                           = modkernel32.NewProc("BackupRead")
+	procBackupWrite                                          = modkernel32.NewProc("BackupWrite")
+)
+
+func cancelIoEx(file syscall.Handle, o *syscall.Overlapped) (err error) {
+	r1, _, e1 := syscall.Syscall(procCancelIoEx.Addr(), 2, uintptr(file), uintptr(unsafe.Pointer(o)), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func createIoCompletionPort(file syscall.Handle, port syscall.Handle, key uintptr, threadCount uint32) (newport syscall.Handle, err error) {
+	r0, _, e1 := syscall.Syscall6(procCreateIoCompletionPort.Addr(), 4, uintptr(file), uintptr(port), uintptr(key), uintptr(threadCount), 0, 0)
+	newport = syscall.Handle(r0)
+	if newport == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func getQueuedCompletionStatus(port syscall.Handle, bytes *uint32, key *uintptr, o **ioOperation, timeout uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procGetQueuedCompletionStatus.Addr(), 5, uintptr(port), uintptr(unsafe.Pointer(bytes)), uintptr(unsafe.Pointer(key)), uintptr(unsafe.Pointer(o)), uintptr(timeout), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func setFileCompletionNotificationModes(h syscall.Handle, flags uint8) (err error) {
+	r1, _, e1 := syscall.Syscall(procSetFileCompletionNotificationModes.Addr(), 2, uintptr(h), uintptr(flags), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func timeBeginPeriod(period uint32) (n int32) {
+	r0, _, _ := syscall.Syscall(proctimeBeginPeriod.Addr(), 1, uintptr(period), 0, 0)
+	n = int32(r0)
+	return
+}
+
+func connectNamedPipe(pipe syscall.Handle, o *syscall.Overlapped) (err error) {
+	r1, _, e1 := syscall.Syscall(procConnectNamedPipe.Addr(), 2, uintptr(pipe), uintptr(unsafe.Pointer(o)), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func createNamedPipe(name string, flags uint32, pipeMode uint32, maxInstances uint32, outSize uint32, inSize uint32, defaultTimeout uint32, sa *securityAttributes) (handle syscall.Handle, err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return
+	}
+	return _createNamedPipe(_p0, flags, pipeMode, maxInstances, outSize, inSize, defaultTimeout, sa)
+}
+
+func _createNamedPipe(name *uint16, flags uint32, pipeMode uint32, maxInstances uint32, outSize uint32, inSize uint32, defaultTimeout uint32, sa *securityAttributes) (handle syscall.Handle, err error) {
+	r0, _, e1 := syscall.Syscall9(procCreateNamedPipeW.Addr(), 8, uintptr(unsafe.Pointer(name)), uintptr(flags), uintptr(pipeMode), uintptr(maxInstances), uintptr(outSize), uintptr(inSize), uintptr(defaultTimeout), uintptr(unsafe.Pointer(sa)), 0)
+	handle = syscall.Handle(r0)
+	if handle == syscall.InvalidHandle {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func createFile(name string, access uint32, mode uint32, sa *securityAttributes, createmode uint32, attrs uint32, templatefile syscall.Handle) (handle syscall.Handle, err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return
+	}
+	return _createFile(_p0, access, mode, sa, createmode, attrs, templatefile)
+}
+
+func _createFile(name *uint16, access uint32, mode uint32, sa *securityAttributes, createmode uint32, attrs uint32, templatefile syscall.Handle) (handle syscall.Handle, err error) {
+	r0, _, e1 := syscall.Syscall9(procCreateFileW.Addr(), 7, uintptr(unsafe.Pointer(name)), uintptr(access), uintptr(mode), uintptr(unsafe.Pointer(sa)), uintptr(createmode), uintptr(attrs), uintptr(templatefile), 0, 0)
+	handle = syscall.Handle(r0)
+	if handle == syscall.InvalidHandle {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func waitNamedPipe(name string, timeout uint32) (err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return
+	}
+	return _waitNamedPipe(_p0, timeout)
+}
+
+func _waitNamedPipe(name *uint16, timeout uint32) (err error) {
+	r1, _, e1 := syscall.Syscall(procWaitNamedPipeW.Addr(), 2, uintptr(unsafe.Pointer(name)), uintptr(timeout), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func getNamedPipeInfo(pipe syscall.Handle, flags *uint32, outSize *uint32, inSize *uint32, maxInstances *uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procGetNamedPipeInfo.Addr(), 5, uintptr(pipe), uintptr(unsafe.Pointer(flags)), uintptr(unsafe.Pointer(outSize)), uintptr(unsafe.Pointer(inSize)), uintptr(unsafe.Pointer(maxInstances)), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func getNamedPipeHandleState(pipe syscall.Handle, state *uint32, curInstances *uint32, maxCollectionCount *uint32, collectDataTimeout *uint32, userName *uint16, maxUserNameSize uint32) (err error) {
+	r1, _, e1 := syscall.Syscall9(procGetNamedPipeHandleStateW.Addr(), 7, uintptr(pipe), uintptr(unsafe.Pointer(state)), uintptr(unsafe.Pointer(curInstances)), uintptr(unsafe.Pointer(maxCollectionCount)), uintptr(unsafe.Pointer(collectDataTimeout)), uintptr(unsafe.Pointer(userName)), uintptr(maxUserNameSize), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func lookupAccountName(systemName *uint16, accountName string, sid *byte, sidSize *uint32, refDomain *uint16, refDomainSize *uint32, sidNameUse *uint32) (err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(accountName)
+	if err != nil {
+		return
+	}
+	return _lookupAccountName(systemName, _p0, sid, sidSize, refDomain, refDomainSize, sidNameUse)
+}
+
+func _lookupAccountName(systemName *uint16, accountName *uint16, sid *byte, sidSize *uint32, refDomain *uint16, refDomainSize *uint32, sidNameUse *uint32) (err error) {
+	r1, _, e1 := syscall.Syscall9(procLookupAccountNameW.Addr(), 7, uintptr(unsafe.Pointer(systemName)), uintptr(unsafe.Pointer(accountName)), uintptr(unsafe.Pointer(sid)), uintptr(unsafe.Pointer(sidSize)), uintptr(unsafe.Pointer(refDomain)), uintptr(unsafe.Pointer(refDomainSize)), uintptr(unsafe.Pointer(sidNameUse)), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func convertSidToStringSid(sid *byte, str **uint16) (err error) {
+	r1, _, e1 := syscall.Syscall(procConvertSidToStringSidW.Addr(), 2, uintptr(unsafe.Pointer(sid)), uintptr(unsafe.Pointer(str)), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func convertStringSecurityDescriptorToSecurityDescriptor(str string, revision uint32, sd *uintptr, size *uint32) (err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(str)
+	if err != nil {
+		return
+	}
+	return _convertStringSecurityDescriptorToSecurityDescriptor(_p0, revision, sd, size)
+}
+
+func _convertStringSecurityDescriptorToSecurityDescriptor(str *uint16, revision uint32, sd *uintptr, size *uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procConvertStringSecurityDescriptorToSecurityDescriptorW.Addr(), 4, uintptr(unsafe.Pointer(str)), uintptr(revision), uintptr(unsafe.Pointer(sd)), uintptr(unsafe.Pointer(size)), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func convertSecurityDescriptorToStringSecurityDescriptor(sd *byte, revision uint32, secInfo uint32, sddl **uint16, sddlSize *uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procConvertSecurityDescriptorToStringSecurityDescriptorW.Addr(), 5, uintptr(unsafe.Pointer(sd)), uintptr(revision), uintptr(secInfo), uintptr(unsafe.Pointer(sddl)), uintptr(unsafe.Pointer(sddlSize)), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func localFree(mem uintptr) {
+	syscall.Syscall(procLocalFree.Addr(), 1, uintptr(mem), 0, 0)
+	return
+}
+
+func getSecurityDescriptorLength(sd uintptr) (len uint32) {
+	r0, _, _ := syscall.Syscall(procGetSecurityDescriptorLength.Addr(), 1, uintptr(sd), 0, 0)
+	len = uint32(r0)
+	return
+}
+
+func getFileInformationByHandleEx(h syscall.Handle, class uint32, buffer *byte, size uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procGetFileInformationByHandleEx.Addr(), 4, uintptr(h), uintptr(class), uintptr(unsafe.Pointer(buffer)), uintptr(size), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func setFileInformationByHandle(h syscall.Handle, class uint32, buffer *byte, size uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procSetFileInformationByHandle.Addr(), 4, uintptr(h), uintptr(class), uintptr(unsafe.Pointer(buffer)), uintptr(size), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func adjustTokenPrivileges(token syscall.Handle, releaseAll bool, input *byte, outputSize uint32, output *byte, requiredSize *uint32) (success bool, err error) {
+	var _p0 uint32
+	if releaseAll {
+		_p0 = 1
+	} else {
+		_p0 = 0
+	}
+	r0, _, e1 := syscall.Syscall6(procAdjustTokenPrivileges.Addr(), 6, uintptr(token), uintptr(_p0), uintptr(unsafe.Pointer(input)), uintptr(outputSize), uintptr(unsafe.Pointer(output)), uintptr(unsafe.Pointer(requiredSize)))
+	success = r0 != 0
+	if true {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func impersonateSelf(level uint32) (err error) {
+	r1, _, e1 := syscall.Syscall(procImpersonateSelf.Addr(), 1, uintptr(level), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func revertToSelf() (err error) {
+	r1, _, e1 := syscall.Syscall(procRevertToSelf.Addr(), 0, 0, 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func openThreadToken(thread syscall.Handle, accessMask uint32, openAsSelf bool, token *syscall.Handle) (err error) {
+	var _p0 uint32
+	if openAsSelf {
+		_p0 = 1
+	} else {
+		_p0 = 0
+	}
+	r1, _, e1 := syscall.Syscall6(procOpenThreadToken.Addr(), 4, uintptr(thread), uintptr(accessMask), uintptr(_p0), uintptr(unsafe.Pointer(token)), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func getCurrentThread() (h syscall.Handle) {
+	r0, _, _ := syscall.Syscall(procGetCurrentThread.Addr(), 0, 0, 0, 0)
+	h = syscall.Handle(r0)
+	return
+}
+
+func lookupPrivilegeValue(systemName string, name string, luid *uint64) (err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(systemName)
+	if err != nil {
+		return
+	}
+	var _p1 *uint16
+	_p1, err = syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return
+	}
+	return _lookupPrivilegeValue(_p0, _p1, luid)
+}
+
+func _lookupPrivilegeValue(systemName *uint16, name *uint16, luid *uint64) (err error) {
+	r1, _, e1 := syscall.Syscall(procLookupPrivilegeValueW.Addr(), 3, uintptr(unsafe.Pointer(systemName)), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(luid)))
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func lookupPrivilegeName(systemName string, luid *uint64, buffer *uint16, size *uint32) (err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(systemName)
+	if err != nil {
+		return
+	}
+	return _lookupPrivilegeName(_p0, luid, buffer, size)
+}
+
+func _lookupPrivilegeName(systemName *uint16, luid *uint64, buffer *uint16, size *uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procLookupPrivilegeNameW.Addr(), 4, uintptr(unsafe.Pointer(systemName)), uintptr(unsafe.Pointer(luid)), uintptr(unsafe.Pointer(buffer)), uintptr(unsafe.Pointer(size)), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func lookupPrivilegeDisplayName(systemName string, name *uint16, buffer *uint16, size *uint32, languageId *uint32) (err error) {
+	var _p0 *uint16
+	_p0, err = syscall.UTF16PtrFromString(systemName)
+	if err != nil {
+		return
+	}
+	return _lookupPrivilegeDisplayName(_p0, name, buffer, size, languageId)
+}
+
+func _lookupPrivilegeDisplayName(systemName *uint16, name *uint16, buffer *uint16, size *uint32, languageId *uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procLookupPrivilegeDisplayNameW.Addr(), 5, uintptr(unsafe.Pointer(systemName)), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(buffer)), uintptr(unsafe.Pointer(size)), uintptr(unsafe.Pointer(languageId)), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func backupRead(h syscall.Handle, b []byte, bytesRead *uint32, abort bool, processSecurity bool, context *uintptr) (err error) {
+	var _p0 *byte
+	if len(b) > 0 {
+		_p0 = &b[0]
+	}
+	var _p1 uint32
+	if abort {
+		_p1 = 1
+	} else {
+		_p1 = 0
+	}
+	var _p2 uint32
+	if processSecurity {
+		_p2 = 1
+	} else {
+		_p2 = 0
+	}
+	r1, _, e1 := syscall.Syscall9(procBackupRead.Addr(), 7, uintptr(h), uintptr(unsafe.Pointer(_p0)), uintptr(len(b)), uintptr(unsafe.Pointer(bytesRead)), uintptr(_p1), uintptr(_p2), uintptr(unsafe.Pointer(context)), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func backupWrite(h syscall.Handle, b []byte, bytesWritten *uint32, abort bool, processSecurity bool, context *uintptr) (err error) {
+	var _p0 *byte
+	if len(b) > 0 {
+		_p0 = &b[0]
+	}
+	var _p1 uint32
+	if abort {
+		_p1 = 1
+	} else {
+		_p1 = 0
+	}
+	var _p2 uint32
+	if processSecurity {
+		_p2 = 1
+	} else {
+		_p2 = 0
+	}
+	r1, _, e1 := syscall.Syscall9(procBackupWrite.Addr(), 7, uintptr(h), uintptr(unsafe.Pointer(_p0)), uintptr(len(b)), uintptr(unsafe.Pointer(bytesWritten)), uintptr(_p1), uintptr(_p2), uintptr(unsafe.Pointer(context)), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}