Use forked archive/tar package
Use fork of archive/tar to carry changes to tar for all go versions. Signed-off-by: Derek McGowan <derek@mcgstyle.net>
This commit is contained in:
Derek McGowan
364
vendor/github.com/dmcgowan/go-tar/writer.go
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364
vendor/github.com/dmcgowan/go-tar/writer.go
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package tar
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// TODO(dsymonds):
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// - catch more errors (no first header, etc.)
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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"path"
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"sort"
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"strconv"
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"strings"
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"time"
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)
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var (
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ErrWriteTooLong = errors.New("archive/tar: write too long")
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ErrFieldTooLong = errors.New("archive/tar: header field too long")
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ErrWriteAfterClose = errors.New("archive/tar: write after close")
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errInvalidHeader = errors.New("archive/tar: header field too long or contains invalid values")
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)
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// A Writer provides sequential writing of a tar archive in POSIX.1 format.
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// A tar archive consists of a sequence of files.
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// Call WriteHeader to begin a new file, and then call Write to supply that file's data,
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// writing at most hdr.Size bytes in total.
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type Writer struct {
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w io.Writer
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err error
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nb int64 // number of unwritten bytes for current file entry
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pad int64 // amount of padding to write after current file entry
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closed bool
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usedBinary bool // whether the binary numeric field extension was used
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preferPax bool // use PAX header instead of binary numeric header
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hdrBuff block // buffer to use in writeHeader when writing a regular header
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paxHdrBuff block // buffer to use in writeHeader when writing a PAX header
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}
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// NewWriter creates a new Writer writing to w.
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func NewWriter(w io.Writer) *Writer { return &Writer{w: w} }
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// Flush finishes writing the current file (optional).
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func (tw *Writer) Flush() error {
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if tw.nb > 0 {
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tw.err = fmt.Errorf("archive/tar: missed writing %d bytes", tw.nb)
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return tw.err
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}
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n := tw.nb + tw.pad
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for n > 0 && tw.err == nil {
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nr := n
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if nr > blockSize {
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nr = blockSize
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}
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var nw int
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nw, tw.err = tw.w.Write(zeroBlock[0:nr])
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n -= int64(nw)
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}
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tw.nb = 0
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tw.pad = 0
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return tw.err
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}
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var (
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minTime = time.Unix(0, 0)
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// There is room for 11 octal digits (33 bits) of mtime.
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maxTime = minTime.Add((1<<33 - 1) * time.Second)
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)
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// WriteHeader writes hdr and prepares to accept the file's contents.
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// WriteHeader calls Flush if it is not the first header.
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// Calling after a Close will return ErrWriteAfterClose.
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func (tw *Writer) WriteHeader(hdr *Header) error {
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return tw.writeHeader(hdr, true)
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}
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// WriteHeader writes hdr and prepares to accept the file's contents.
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// WriteHeader calls Flush if it is not the first header.
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// Calling after a Close will return ErrWriteAfterClose.
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// As this method is called internally by writePax header to allow it to
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// suppress writing the pax header.
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func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
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if tw.closed {
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return ErrWriteAfterClose
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}
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if tw.err == nil {
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tw.Flush()
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}
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if tw.err != nil {
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return tw.err
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}
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// a map to hold pax header records, if any are needed
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paxHeaders := make(map[string]string)
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// TODO(dsnet): we might want to use PAX headers for
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// subsecond time resolution, but for now let's just capture
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// too long fields or non ascii characters
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// We need to select which scratch buffer to use carefully,
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// since this method is called recursively to write PAX headers.
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// If allowPax is true, this is the non-recursive call, and we will use hdrBuff.
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// If allowPax is false, we are being called by writePAXHeader, and hdrBuff is
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// already being used by the non-recursive call, so we must use paxHdrBuff.
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header := &tw.hdrBuff
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if !allowPax {
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header = &tw.paxHdrBuff
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}
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copy(header[:], zeroBlock[:])
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// Wrappers around formatter that automatically sets paxHeaders if the
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// argument extends beyond the capacity of the input byte slice.
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var f formatter
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var formatString = func(b []byte, s string, paxKeyword string) {
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needsPaxHeader := paxKeyword != paxNone && len(s) > len(b) || !isASCII(s)
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if needsPaxHeader {
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paxHeaders[paxKeyword] = s
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return
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}
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f.formatString(b, s)
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}
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var formatNumeric = func(b []byte, x int64, paxKeyword string) {
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// Try octal first.
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s := strconv.FormatInt(x, 8)
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if len(s) < len(b) {
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f.formatOctal(b, x)
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return
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}
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// If it is too long for octal, and PAX is preferred, use a PAX header.
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if paxKeyword != paxNone && tw.preferPax {
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f.formatOctal(b, 0)
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s := strconv.FormatInt(x, 10)
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paxHeaders[paxKeyword] = s
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return
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}
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tw.usedBinary = true
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f.formatNumeric(b, x)
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}
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// Handle out of range ModTime carefully.
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var modTime int64
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if !hdr.ModTime.Before(minTime) && !hdr.ModTime.After(maxTime) {
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modTime = hdr.ModTime.Unix()
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}
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v7 := header.V7()
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formatString(v7.Name(), hdr.Name, paxPath)
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// TODO(dsnet): The GNU format permits the mode field to be encoded in
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// base-256 format. Thus, we can use formatNumeric instead of formatOctal.
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f.formatOctal(v7.Mode(), hdr.Mode)
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formatNumeric(v7.UID(), int64(hdr.Uid), paxUid)
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formatNumeric(v7.GID(), int64(hdr.Gid), paxGid)
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formatNumeric(v7.Size(), hdr.Size, paxSize)
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// TODO(dsnet): Consider using PAX for finer time granularity.
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formatNumeric(v7.ModTime(), modTime, paxNone)
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v7.TypeFlag()[0] = hdr.Typeflag
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formatString(v7.LinkName(), hdr.Linkname, paxLinkpath)
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ustar := header.USTAR()
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formatString(ustar.UserName(), hdr.Uname, paxUname)
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formatString(ustar.GroupName(), hdr.Gname, paxGname)
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formatNumeric(ustar.DevMajor(), hdr.Devmajor, paxNone)
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formatNumeric(ustar.DevMinor(), hdr.Devminor, paxNone)
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// TODO(dsnet): The logic surrounding the prefix field is broken when trying
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// to encode the header as GNU format. The challenge with the current logic
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// is that we are unsure what format we are using at any given moment until
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// we have processed *all* of the fields. The problem is that by the time
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// all fields have been processed, some work has already been done to handle
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// each field under the assumption that it is for one given format or
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// another. In some situations, this causes the Writer to be confused and
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// encode a prefix field when the format being used is GNU. Thus, producing
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// an invalid tar file.
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//
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// As a short-term fix, we disable the logic to use the prefix field, which
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// will force the badly generated GNU files to become encoded as being
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// the PAX format.
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//
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// As an alternative fix, we could hard-code preferPax to be true. However,
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// this is problematic for the following reasons:
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// * The preferPax functionality is not tested at all.
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// * This can result in headers that try to use both the GNU and PAX
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// features at the same time, which is also wrong.
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//
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// The proper fix for this is to use a two-pass method:
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// * The first pass simply determines what set of formats can possibly
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// encode the given header.
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// * The second pass actually encodes the header as that given format
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// without worrying about violating the format.
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//
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// See the following:
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// https://golang.org/issue/12594
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// https://golang.org/issue/17630
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// https://golang.org/issue/9683
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const usePrefix = false
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// try to use a ustar header when only the name is too long
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_, paxPathUsed := paxHeaders[paxPath]
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if usePrefix && !tw.preferPax && len(paxHeaders) == 1 && paxPathUsed {
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prefix, suffix, ok := splitUSTARPath(hdr.Name)
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if ok {
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// Since we can encode in USTAR format, disable PAX header.
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delete(paxHeaders, paxPath)
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// Update the path fields
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formatString(v7.Name(), suffix, paxNone)
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formatString(ustar.Prefix(), prefix, paxNone)
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}
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}
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if tw.usedBinary {
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header.SetFormat(formatGNU)
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} else {
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header.SetFormat(formatUSTAR)
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}
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// Check if there were any formatting errors.
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if f.err != nil {
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tw.err = f.err
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return tw.err
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}
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if allowPax {
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for k, v := range hdr.Xattrs {
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paxHeaders[paxXattr+k] = v
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}
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}
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if len(paxHeaders) > 0 {
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if !allowPax {
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return errInvalidHeader
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}
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if err := tw.writePAXHeader(hdr, paxHeaders); err != nil {
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return err
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}
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}
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tw.nb = hdr.Size
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tw.pad = (blockSize - (tw.nb % blockSize)) % blockSize
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_, tw.err = tw.w.Write(header[:])
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return tw.err
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}
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// splitUSTARPath splits a path according to USTAR prefix and suffix rules.
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// If the path is not splittable, then it will return ("", "", false).
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func splitUSTARPath(name string) (prefix, suffix string, ok bool) {
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length := len(name)
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if length <= nameSize || !isASCII(name) {
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return "", "", false
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} else if length > prefixSize+1 {
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length = prefixSize + 1
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} else if name[length-1] == '/' {
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length--
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}
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i := strings.LastIndex(name[:length], "/")
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nlen := len(name) - i - 1 // nlen is length of suffix
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plen := i // plen is length of prefix
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if i <= 0 || nlen > nameSize || nlen == 0 || plen > prefixSize {
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return "", "", false
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}
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return name[:i], name[i+1:], true
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}
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// writePaxHeader writes an extended pax header to the
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// archive.
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func (tw *Writer) writePAXHeader(hdr *Header, paxHeaders map[string]string) error {
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// Prepare extended header
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ext := new(Header)
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ext.Typeflag = TypeXHeader
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// Setting ModTime is required for reader parsing to
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// succeed, and seems harmless enough.
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ext.ModTime = hdr.ModTime
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// The spec asks that we namespace our pseudo files
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// with the current pid. However, this results in differing outputs
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// for identical inputs. As such, the constant 0 is now used instead.
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// golang.org/issue/12358
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dir, file := path.Split(hdr.Name)
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fullName := path.Join(dir, "PaxHeaders.0", file)
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ascii := toASCII(fullName)
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if len(ascii) > nameSize {
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ascii = ascii[:nameSize]
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}
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ext.Name = ascii
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// Construct the body
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var buf bytes.Buffer
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// Keys are sorted before writing to body to allow deterministic output.
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keys := make([]string, 0, len(paxHeaders))
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for k := range paxHeaders {
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keys = append(keys, k)
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}
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sort.Strings(keys)
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for _, k := range keys {
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fmt.Fprint(&buf, formatPAXRecord(k, paxHeaders[k]))
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}
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ext.Size = int64(len(buf.Bytes()))
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if err := tw.writeHeader(ext, false); err != nil {
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return err
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}
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if _, err := tw.Write(buf.Bytes()); err != nil {
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return err
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}
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if err := tw.Flush(); err != nil {
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return err
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}
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return nil
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}
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// Write writes to the current entry in the tar archive.
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// Write returns the error ErrWriteTooLong if more than
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// hdr.Size bytes are written after WriteHeader.
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func (tw *Writer) Write(b []byte) (n int, err error) {
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if tw.closed {
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err = ErrWriteAfterClose
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return
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}
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overwrite := false
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if int64(len(b)) > tw.nb {
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b = b[0:tw.nb]
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overwrite = true
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}
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n, err = tw.w.Write(b)
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tw.nb -= int64(n)
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if err == nil && overwrite {
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err = ErrWriteTooLong
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return
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}
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tw.err = err
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return
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}
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// Close closes the tar archive, flushing any unwritten
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// data to the underlying writer.
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func (tw *Writer) Close() error {
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if tw.err != nil || tw.closed {
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return tw.err
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}
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tw.Flush()
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tw.closed = true
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if tw.err != nil {
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return tw.err
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}
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// trailer: two zero blocks
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for i := 0; i < 2; i++ {
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_, tw.err = tw.w.Write(zeroBlock[:])
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if tw.err != nil {
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break
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}
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}
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return tw.err
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}
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