1 files changed, 659 insertions, 0 deletions

diff --git a/src/archive/tar/writer.go b/src/archive/tar/writer.go
new file mode 100644
index 0000000..1c95f07
--- /dev/null
+++ b/src/archive/tar/writer.go
@@ -0,0 +1,659 @@
+// 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
+
+import (
+	"fmt"
+	"io"
+	"path"
+	"sort"
+	"strings"
+	"time"
+)
+
+// Writer provides sequential writing of a tar archive.
+// Write.WriteHeader begins a new file with the provided Header,
+// and then Writer can be treated as an io.Writer to supply that file's data.
+type Writer struct {
+	w    io.Writer
+	pad  int64      // Amount of padding to write after current file entry
+	curr fileWriter // Writer for current file entry
+	hdr  Header     // Shallow copy of Header that is safe for mutations
+	blk  block      // Buffer to use as temporary local storage
+
+	// err is a persistent error.
+	// It is only the responsibility of every exported method of Writer to
+	// ensure that this error is sticky.
+	err error
+}
+
+// NewWriter creates a new Writer writing to w.
+func NewWriter(w io.Writer) *Writer {
+	return &Writer{w: w, curr: &regFileWriter{w, 0}}
+}
+
+type fileWriter interface {
+	io.Writer
+	fileState
+
+	ReadFrom(io.Reader) (int64, error)
+}
+
+// Flush finishes writing the current file's block padding.
+// The current file must be fully written before Flush can be called.
+//
+// This is unnecessary as the next call to WriteHeader or Close
+// will implicitly flush out the file's padding.
+func (tw *Writer) Flush() error {
+	if tw.err != nil {
+		return tw.err
+	}
+	if nb := tw.curr.logicalRemaining(); nb > 0 {
+		return fmt.Errorf("archive/tar: missed writing %d bytes", nb)
+	}
+	if _, tw.err = tw.w.Write(zeroBlock[:tw.pad]); tw.err != nil {
+		return tw.err
+	}
+	tw.pad = 0
+	return nil
+}
+
+// WriteHeader writes hdr and prepares to accept the file's contents.
+// The Header.Size determines how many bytes can be written for the next file.
+// If the current file is not fully written, then this returns an error.
+// This implicitly flushes any padding necessary before writing the header.
+func (tw *Writer) WriteHeader(hdr *Header) error {
+	if err := tw.Flush(); err != nil {
+		return err
+	}
+	tw.hdr = *hdr // Shallow copy of Header
+
+	// Avoid usage of the legacy TypeRegA flag, and automatically promote
+	// it to use TypeReg or TypeDir.
+	if tw.hdr.Typeflag == TypeRegA {
+		if strings.HasSuffix(tw.hdr.Name, "/") {
+			tw.hdr.Typeflag = TypeDir
+		} else {
+			tw.hdr.Typeflag = TypeReg
+		}
+	}
+
+	// Round ModTime and ignore AccessTime and ChangeTime unless
+	// the format is explicitly chosen.
+	// This ensures nominal usage of WriteHeader (without specifying the format)
+	// does not always result in the PAX format being chosen, which
+	// causes a 1KiB increase to every header.
+	if tw.hdr.Format == FormatUnknown {
+		tw.hdr.ModTime = tw.hdr.ModTime.Round(time.Second)
+		tw.hdr.AccessTime = time.Time{}
+		tw.hdr.ChangeTime = time.Time{}
+	}
+
+	allowedFormats, paxHdrs, err := tw.hdr.allowedFormats()
+	switch {
+	case allowedFormats.has(FormatUSTAR):
+		tw.err = tw.writeUSTARHeader(&tw.hdr)
+		return tw.err
+	case allowedFormats.has(FormatPAX):
+		tw.err = tw.writePAXHeader(&tw.hdr, paxHdrs)
+		return tw.err
+	case allowedFormats.has(FormatGNU):
+		tw.err = tw.writeGNUHeader(&tw.hdr)
+		return tw.err
+	default:
+		return err // Non-fatal error
+	}
+}
+
+func (tw *Writer) writeUSTARHeader(hdr *Header) error {
+	// Check if we can use USTAR prefix/suffix splitting.
+	var namePrefix string
+	if prefix, suffix, ok := splitUSTARPath(hdr.Name); ok {
+		namePrefix, hdr.Name = prefix, suffix
+	}
+
+	// Pack the main header.
+	var f formatter
+	blk := tw.templateV7Plus(hdr, f.formatString, f.formatOctal)
+	f.formatString(blk.toUSTAR().prefix(), namePrefix)
+	blk.setFormat(FormatUSTAR)
+	if f.err != nil {
+		return f.err // Should never happen since header is validated
+	}
+	return tw.writeRawHeader(blk, hdr.Size, hdr.Typeflag)
+}
+
+func (tw *Writer) writePAXHeader(hdr *Header, paxHdrs map[string]string) error {
+	realName, realSize := hdr.Name, hdr.Size
+
+	// TODO(dsnet): Re-enable this when adding sparse support.
+	// See https://golang.org/issue/22735
+	/*
+		// Handle sparse files.
+		var spd sparseDatas
+		var spb []byte
+		if len(hdr.SparseHoles) > 0 {
+			sph := append([]sparseEntry{}, hdr.SparseHoles...) // Copy sparse map
+			sph = alignSparseEntries(sph, hdr.Size)
+			spd = invertSparseEntries(sph, hdr.Size)
+
+			// Format the sparse map.
+			hdr.Size = 0 // Replace with encoded size
+			spb = append(strconv.AppendInt(spb, int64(len(spd)), 10), '\n')
+			for _, s := range spd {
+				hdr.Size += s.Length
+				spb = append(strconv.AppendInt(spb, s.Offset, 10), '\n')
+				spb = append(strconv.AppendInt(spb, s.Length, 10), '\n')
+			}
+			pad := blockPadding(int64(len(spb)))
+			spb = append(spb, zeroBlock[:pad]...)
+			hdr.Size += int64(len(spb)) // Accounts for encoded sparse map
+
+			// Add and modify appropriate PAX records.
+			dir, file := path.Split(realName)
+			hdr.Name = path.Join(dir, "GNUSparseFile.0", file)
+			paxHdrs[paxGNUSparseMajor] = "1"
+			paxHdrs[paxGNUSparseMinor] = "0"
+			paxHdrs[paxGNUSparseName] = realName
+			paxHdrs[paxGNUSparseRealSize] = strconv.FormatInt(realSize, 10)
+			paxHdrs[paxSize] = strconv.FormatInt(hdr.Size, 10)
+			delete(paxHdrs, paxPath) // Recorded by paxGNUSparseName
+		}
+	*/
+	_ = realSize
+
+	// Write PAX records to the output.
+	isGlobal := hdr.Typeflag == TypeXGlobalHeader
+	if len(paxHdrs) > 0 || isGlobal {
+		// Sort keys for deterministic ordering.
+		var keys []string
+		for k := range paxHdrs {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+
+		// Write each record to a buffer.
+		var buf strings.Builder
+		for _, k := range keys {
+			rec, err := formatPAXRecord(k, paxHdrs[k])
+			if err != nil {
+				return err
+			}
+			buf.WriteString(rec)
+		}
+
+		// Write the extended header file.
+		var name string
+		var flag byte
+		if isGlobal {
+			name = realName
+			if name == "" {
+				name = "GlobalHead.0.0"
+			}
+			flag = TypeXGlobalHeader
+		} else {
+			dir, file := path.Split(realName)
+			name = path.Join(dir, "PaxHeaders.0", file)
+			flag = TypeXHeader
+		}
+		data := buf.String()
+		if len(data) > maxSpecialFileSize {
+			return ErrFieldTooLong
+		}
+		if err := tw.writeRawFile(name, data, flag, FormatPAX); err != nil || isGlobal {
+			return err // Global headers return here
+		}
+	}
+
+	// Pack the main header.
+	var f formatter // Ignore errors since they are expected
+	fmtStr := func(b []byte, s string) { f.formatString(b, toASCII(s)) }
+	blk := tw.templateV7Plus(hdr, fmtStr, f.formatOctal)
+	blk.setFormat(FormatPAX)
+	if err := tw.writeRawHeader(blk, hdr.Size, hdr.Typeflag); err != nil {
+		return err
+	}
+
+	// TODO(dsnet): Re-enable this when adding sparse support.
+	// See https://golang.org/issue/22735
+	/*
+		// Write the sparse map and setup the sparse writer if necessary.
+		if len(spd) > 0 {
+			// Use tw.curr since the sparse map is accounted for in hdr.Size.
+			if _, err := tw.curr.Write(spb); err != nil {
+				return err
+			}
+			tw.curr = &sparseFileWriter{tw.curr, spd, 0}
+		}
+	*/
+	return nil
+}
+
+func (tw *Writer) writeGNUHeader(hdr *Header) error {
+	// Use long-link files if Name or Linkname exceeds the field size.
+	const longName = "././@LongLink"
+	if len(hdr.Name) > nameSize {
+		data := hdr.Name + "\x00"
+		if err := tw.writeRawFile(longName, data, TypeGNULongName, FormatGNU); err != nil {
+			return err
+		}
+	}
+	if len(hdr.Linkname) > nameSize {
+		data := hdr.Linkname + "\x00"
+		if err := tw.writeRawFile(longName, data, TypeGNULongLink, FormatGNU); err != nil {
+			return err
+		}
+	}
+
+	// Pack the main header.
+	var f formatter // Ignore errors since they are expected
+	var spd sparseDatas
+	var spb []byte
+	blk := tw.templateV7Plus(hdr, f.formatString, f.formatNumeric)
+	if !hdr.AccessTime.IsZero() {
+		f.formatNumeric(blk.toGNU().accessTime(), hdr.AccessTime.Unix())
+	}
+	if !hdr.ChangeTime.IsZero() {
+		f.formatNumeric(blk.toGNU().changeTime(), hdr.ChangeTime.Unix())
+	}
+	// TODO(dsnet): Re-enable this when adding sparse support.
+	// See https://golang.org/issue/22735
+	/*
+		if hdr.Typeflag == TypeGNUSparse {
+			sph := append([]sparseEntry{}, hdr.SparseHoles...) // Copy sparse map
+			sph = alignSparseEntries(sph, hdr.Size)
+			spd = invertSparseEntries(sph, hdr.Size)
+
+			// Format the sparse map.
+			formatSPD := func(sp sparseDatas, sa sparseArray) sparseDatas {
+				for i := 0; len(sp) > 0 && i < sa.MaxEntries(); i++ {
+					f.formatNumeric(sa.Entry(i).Offset(), sp[0].Offset)
+					f.formatNumeric(sa.Entry(i).Length(), sp[0].Length)
+					sp = sp[1:]
+				}
+				if len(sp) > 0 {
+					sa.IsExtended()[0] = 1
+				}
+				return sp
+			}
+			sp2 := formatSPD(spd, blk.GNU().Sparse())
+			for len(sp2) > 0 {
+				var spHdr block
+				sp2 = formatSPD(sp2, spHdr.Sparse())
+				spb = append(spb, spHdr[:]...)
+			}
+
+			// Update size fields in the header block.
+			realSize := hdr.Size
+			hdr.Size = 0 // Encoded size; does not account for encoded sparse map
+			for _, s := range spd {
+				hdr.Size += s.Length
+			}
+			copy(blk.V7().Size(), zeroBlock[:]) // Reset field
+			f.formatNumeric(blk.V7().Size(), hdr.Size)
+			f.formatNumeric(blk.GNU().RealSize(), realSize)
+		}
+	*/
+	blk.setFormat(FormatGNU)
+	if err := tw.writeRawHeader(blk, hdr.Size, hdr.Typeflag); err != nil {
+		return err
+	}
+
+	// Write the extended sparse map and setup the sparse writer if necessary.
+	if len(spd) > 0 {
+		// Use tw.w since the sparse map is not accounted for in hdr.Size.
+		if _, err := tw.w.Write(spb); err != nil {
+			return err
+		}
+		tw.curr = &sparseFileWriter{tw.curr, spd, 0}
+	}
+	return nil
+}
+
+type (
+	stringFormatter func([]byte, string)
+	numberFormatter func([]byte, int64)
+)
+
+// templateV7Plus fills out the V7 fields of a block using values from hdr.
+// It also fills out fields (uname, gname, devmajor, devminor) that are
+// shared in the USTAR, PAX, and GNU formats using the provided formatters.
+//
+// The block returned is only valid until the next call to
+// templateV7Plus or writeRawFile.
+func (tw *Writer) templateV7Plus(hdr *Header, fmtStr stringFormatter, fmtNum numberFormatter) *block {
+	tw.blk.reset()
+
+	modTime := hdr.ModTime
+	if modTime.IsZero() {
+		modTime = time.Unix(0, 0)
+	}
+
+	v7 := tw.blk.toV7()
+	v7.typeFlag()[0] = hdr.Typeflag
+	fmtStr(v7.name(), hdr.Name)
+	fmtStr(v7.linkName(), hdr.Linkname)
+	fmtNum(v7.mode(), hdr.Mode)
+	fmtNum(v7.uid(), int64(hdr.Uid))
+	fmtNum(v7.gid(), int64(hdr.Gid))
+	fmtNum(v7.size(), hdr.Size)
+	fmtNum(v7.modTime(), modTime.Unix())
+
+	ustar := tw.blk.toUSTAR()
+	fmtStr(ustar.userName(), hdr.Uname)
+	fmtStr(ustar.groupName(), hdr.Gname)
+	fmtNum(ustar.devMajor(), hdr.Devmajor)
+	fmtNum(ustar.devMinor(), hdr.Devminor)
+
+	return &tw.blk
+}
+
+// writeRawFile writes a minimal file with the given name and flag type.
+// It uses format to encode the header format and will write data as the body.
+// It uses default values for all of the other fields (as BSD and GNU tar does).
+func (tw *Writer) writeRawFile(name, data string, flag byte, format Format) error {
+	tw.blk.reset()
+
+	// Best effort for the filename.
+	name = toASCII(name)
+	if len(name) > nameSize {
+		name = name[:nameSize]
+	}
+	name = strings.TrimRight(name, "/")
+
+	var f formatter
+	v7 := tw.blk.toV7()
+	v7.typeFlag()[0] = flag
+	f.formatString(v7.name(), name)
+	f.formatOctal(v7.mode(), 0)
+	f.formatOctal(v7.uid(), 0)
+	f.formatOctal(v7.gid(), 0)
+	f.formatOctal(v7.size(), int64(len(data))) // Must be < 8GiB
+	f.formatOctal(v7.modTime(), 0)
+	tw.blk.setFormat(format)
+	if f.err != nil {
+		return f.err // Only occurs if size condition is violated
+	}
+
+	// Write the header and data.
+	if err := tw.writeRawHeader(&tw.blk, int64(len(data)), flag); err != nil {
+		return err
+	}
+	_, err := io.WriteString(tw, data)
+	return err
+}
+
+// writeRawHeader writes the value of blk, regardless of its value.
+// It sets up the Writer such that it can accept a file of the given size.
+// If the flag is a special header-only flag, then the size is treated as zero.
+func (tw *Writer) writeRawHeader(blk *block, size int64, flag byte) error {
+	if err := tw.Flush(); err != nil {
+		return err
+	}
+	if _, err := tw.w.Write(blk[:]); err != nil {
+		return err
+	}
+	if isHeaderOnlyType(flag) {
+		size = 0
+	}
+	tw.curr = &regFileWriter{tw.w, size}
+	tw.pad = blockPadding(size)
+	return nil
+}
+
+// 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 <= nameSize || !isASCII(name) {
+		return "", "", false
+	} else if length > prefixSize+1 {
+		length = prefixSize + 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 > nameSize || nlen == 0 || plen > prefixSize {
+		return "", "", false
+	}
+	return name[:i], name[i+1:], true
+}
+
+// Write writes to the current file in the tar archive.
+// Write returns the error ErrWriteTooLong if more than
+// Header.Size bytes are written after WriteHeader.
+//
+// Calling Write on special types like TypeLink, TypeSymlink, TypeChar,
+// TypeBlock, TypeDir, and TypeFifo returns (0, ErrWriteTooLong) regardless
+// of what the Header.Size claims.
+func (tw *Writer) Write(b []byte) (int, error) {
+	if tw.err != nil {
+		return 0, tw.err
+	}
+	n, err := tw.curr.Write(b)
+	if err != nil && err != ErrWriteTooLong {
+		tw.err = err
+	}
+	return n, err
+}
+
+// readFrom populates the content of the current file by reading from r.
+// The bytes read must match the number of remaining bytes in the current file.
+//
+// If the current file is sparse and r is an io.ReadSeeker,
+// then readFrom uses Seek to skip past holes defined in Header.SparseHoles,
+// assuming that skipped regions are all NULs.
+// This always reads the last byte to ensure r is the right size.
+//
+// TODO(dsnet): Re-export this when adding sparse file support.
+// See https://golang.org/issue/22735
+func (tw *Writer) readFrom(r io.Reader) (int64, error) {
+	if tw.err != nil {
+		return 0, tw.err
+	}
+	n, err := tw.curr.ReadFrom(r)
+	if err != nil && err != ErrWriteTooLong {
+		tw.err = err
+	}
+	return n, err
+}
+
+// Close closes the tar archive by flushing the padding, and writing the footer.
+// If the current file (from a prior call to WriteHeader) is not fully written,
+// then this returns an error.
+func (tw *Writer) Close() error {
+	if tw.err == ErrWriteAfterClose {
+		return nil
+	}
+	if tw.err != nil {
+		return tw.err
+	}
+
+	// Trailer: two zero blocks.
+	err := tw.Flush()
+	for i := 0; i < 2 && err == nil; i++ {
+		_, err = tw.w.Write(zeroBlock[:])
+	}
+
+	// Ensure all future actions are invalid.
+	tw.err = ErrWriteAfterClose
+	return err // Report IO errors
+}
+
+// regFileWriter is a fileWriter for writing data to a regular file entry.
+type regFileWriter struct {
+	w  io.Writer // Underlying Writer
+	nb int64     // Number of remaining bytes to write
+}
+
+func (fw *regFileWriter) Write(b []byte) (n int, err error) {
+	overwrite := int64(len(b)) > fw.nb
+	if overwrite {
+		b = b[:fw.nb]
+	}
+	if len(b) > 0 {
+		n, err = fw.w.Write(b)
+		fw.nb -= int64(n)
+	}
+	switch {
+	case err != nil:
+		return n, err
+	case overwrite:
+		return n, ErrWriteTooLong
+	default:
+		return n, nil
+	}
+}
+
+func (fw *regFileWriter) ReadFrom(r io.Reader) (int64, error) {
+	return io.Copy(struct{ io.Writer }{fw}, r)
+}
+
+// logicalRemaining implements fileState.logicalRemaining.
+func (fw regFileWriter) logicalRemaining() int64 {
+	return fw.nb
+}
+
+// physicalRemaining implements fileState.physicalRemaining.
+func (fw regFileWriter) physicalRemaining() int64 {
+	return fw.nb
+}
+
+// sparseFileWriter is a fileWriter for writing data to a sparse file entry.
+type sparseFileWriter struct {
+	fw  fileWriter  // Underlying fileWriter
+	sp  sparseDatas // Normalized list of data fragments
+	pos int64       // Current position in sparse file
+}
+
+func (sw *sparseFileWriter) Write(b []byte) (n int, err error) {
+	overwrite := int64(len(b)) > sw.logicalRemaining()
+	if overwrite {
+		b = b[:sw.logicalRemaining()]
+	}
+
+	b0 := b
+	endPos := sw.pos + int64(len(b))
+	for endPos > sw.pos && err == nil {
+		var nf int // Bytes written in fragment
+		dataStart, dataEnd := sw.sp[0].Offset, sw.sp[0].endOffset()
+		if sw.pos < dataStart { // In a hole fragment
+			bf := b[:min(int64(len(b)), dataStart-sw.pos)]
+			nf, err = zeroWriter{}.Write(bf)
+		} else { // In a data fragment
+			bf := b[:min(int64(len(b)), dataEnd-sw.pos)]
+			nf, err = sw.fw.Write(bf)
+		}
+		b = b[nf:]
+		sw.pos += int64(nf)
+		if sw.pos >= dataEnd && len(sw.sp) > 1 {
+			sw.sp = sw.sp[1:] // Ensure last fragment always remains
+		}
+	}
+
+	n = len(b0) - len(b)
+	switch {
+	case err == ErrWriteTooLong:
+		return n, errMissData // Not possible; implies bug in validation logic
+	case err != nil:
+		return n, err
+	case sw.logicalRemaining() == 0 && sw.physicalRemaining() > 0:
+		return n, errUnrefData // Not possible; implies bug in validation logic
+	case overwrite:
+		return n, ErrWriteTooLong
+	default:
+		return n, nil
+	}
+}
+
+func (sw *sparseFileWriter) ReadFrom(r io.Reader) (n int64, err error) {
+	rs, ok := r.(io.ReadSeeker)
+	if ok {
+		if _, err := rs.Seek(0, io.SeekCurrent); err != nil {
+			ok = false // Not all io.Seeker can really seek
+		}
+	}
+	if !ok {
+		return io.Copy(struct{ io.Writer }{sw}, r)
+	}
+
+	var readLastByte bool
+	pos0 := sw.pos
+	for sw.logicalRemaining() > 0 && !readLastByte && err == nil {
+		var nf int64 // Size of fragment
+		dataStart, dataEnd := sw.sp[0].Offset, sw.sp[0].endOffset()
+		if sw.pos < dataStart { // In a hole fragment
+			nf = dataStart - sw.pos
+			if sw.physicalRemaining() == 0 {
+				readLastByte = true
+				nf--
+			}
+			_, err = rs.Seek(nf, io.SeekCurrent)
+		} else { // In a data fragment
+			nf = dataEnd - sw.pos
+			nf, err = io.CopyN(sw.fw, rs, nf)
+		}
+		sw.pos += nf
+		if sw.pos >= dataEnd && len(sw.sp) > 1 {
+			sw.sp = sw.sp[1:] // Ensure last fragment always remains
+		}
+	}
+
+	// If the last fragment is a hole, then seek to 1-byte before EOF, and
+	// read a single byte to ensure the file is the right size.
+	if readLastByte && err == nil {
+		_, err = mustReadFull(rs, []byte{0})
+		sw.pos++
+	}
+
+	n = sw.pos - pos0
+	switch {
+	case err == io.EOF:
+		return n, io.ErrUnexpectedEOF
+	case err == ErrWriteTooLong:
+		return n, errMissData // Not possible; implies bug in validation logic
+	case err != nil:
+		return n, err
+	case sw.logicalRemaining() == 0 && sw.physicalRemaining() > 0:
+		return n, errUnrefData // Not possible; implies bug in validation logic
+	default:
+		return n, ensureEOF(rs)
+	}
+}
+
+func (sw sparseFileWriter) logicalRemaining() int64 {
+	return sw.sp[len(sw.sp)-1].endOffset() - sw.pos
+}
+func (sw sparseFileWriter) physicalRemaining() int64 {
+	return sw.fw.physicalRemaining()
+}
+
+// zeroWriter may only be written with NULs, otherwise it returns errWriteHole.
+type zeroWriter struct{}
+
+func (zeroWriter) Write(b []byte) (int, error) {
+	for i, c := range b {
+		if c != 0 {
+			return i, errWriteHole
+		}
+	}
+	return len(b), nil
+}
+
+// ensureEOF checks whether r is at EOF, reporting ErrWriteTooLong if not so.
+func ensureEOF(r io.Reader) error {
+	n, err := tryReadFull(r, []byte{0})
+	switch {
+	case n > 0:
+		return ErrWriteTooLong
+	case err == io.EOF:
+		return nil
+	default:
+		return err
+	}
+}