diff options
Diffstat (limited to 'src/pkg/archive/tar/writer.go')
| -rw-r--r-- | src/pkg/archive/tar/writer.go | 383 |
1 files changed, 0 insertions, 383 deletions
diff --git a/src/pkg/archive/tar/writer.go b/src/pkg/archive/tar/writer.go deleted file mode 100644 index 6eff6f6f8..000000000 --- a/src/pkg/archive/tar/writer.go +++ /dev/null @@ -1,383 +0,0 @@ -// 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" - "os" - "path" - "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") - errNameTooLong = errors.New("archive/tar: name too long") - 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 -} - -// 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. -// If the value is too long for the field and allowPax is true add a paxheader record instead -func (tw *Writer) cString(b []byte, s string, allowPax bool, paxKeyword string, paxHeaders map[string]string) { - needsPaxHeader := allowPax && len(s) > len(b) || !isASCII(s) - if needsPaxHeader { - paxHeaders[paxKeyword] = s - return - } - if len(s) > len(b) { - if tw.err == nil { - tw.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 (tw *Writer) octal(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 - } - tw.cString(b, s, false, paxNone, nil) -} - -// Write x into b, either as octal or as binary (GNUtar/star extension). -// If the value is too long for the field and writingPax is enabled both for the field and the add a paxheader record instead -func (tw *Writer) numeric(b []byte, x int64, allowPax bool, paxKeyword string, paxHeaders map[string]string) { - // Try octal first. - s := strconv.FormatInt(x, 8) - if len(s) < len(b) { - tw.octal(b, x) - return - } - - // If it is too long for octal, and pax is preferred, use a pax header - if allowPax && tw.preferPax { - tw.octal(b, 0) - s := strconv.FormatInt(x, 10) - paxHeaders[paxKeyword] = s - return - } - - // Too big: use binary (big-endian). - tw.usedBinary = true - for i := len(b) - 1; x > 0 && i >= 0; i-- { - b[i] = byte(x) - x >>= 8 - } - b[0] |= 0x80 // highest bit indicates binary format -} - -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 - - header := make([]byte, blockSize) - s := slicer(header) - - // 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) - - tw.cString(pathHeaderBytes, hdr.Name, true, paxPath, paxHeaders) - - // Handle out of range ModTime carefully. - var modTime int64 - if !hdr.ModTime.Before(minTime) && !hdr.ModTime.After(maxTime) { - modTime = hdr.ModTime.Unix() - } - - tw.octal(s.next(8), hdr.Mode) // 100:108 - tw.numeric(s.next(8), int64(hdr.Uid), true, paxUid, paxHeaders) // 108:116 - tw.numeric(s.next(8), int64(hdr.Gid), true, paxGid, paxHeaders) // 116:124 - tw.numeric(s.next(12), hdr.Size, true, paxSize, paxHeaders) // 124:136 - tw.numeric(s.next(12), modTime, false, paxNone, nil) // 136:148 --- consider using pax for finer granularity - s.next(8) // chksum (148:156) - s.next(1)[0] = hdr.Typeflag // 156:157 - - tw.cString(s.next(100), hdr.Linkname, true, paxLinkpath, paxHeaders) - - copy(s.next(8), []byte("ustar\x0000")) // 257:265 - tw.cString(s.next(32), hdr.Uname, true, paxUname, paxHeaders) // 265:297 - tw.cString(s.next(32), hdr.Gname, true, paxGname, paxHeaders) // 297:329 - tw.numeric(s.next(8), hdr.Devmajor, false, paxNone, nil) // 329:337 - tw.numeric(s.next(8), hdr.Devminor, false, paxNone, nil) // 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) - tw.cString(prefixHeaderBytes, "", false, paxNone, nil) // 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 { - suffix := hdr.Name - prefix := "" - if len(hdr.Name) > fileNameSize && isASCII(hdr.Name) { - var err error - prefix, suffix, err = tw.splitUSTARLongName(hdr.Name) - if err == nil { - // ok we can use a ustar long name instead of pax, now correct the fields - - // remove the path field from the pax header. this will suppress the pax header - delete(paxHeaders, paxPath) - - // update the path fields - tw.cString(pathHeaderBytes, suffix, false, paxNone, nil) - tw.cString(prefixHeaderBytes, prefix, false, paxNone, nil) - - // Use the ustar magic if we used ustar long names. - if len(prefix) > 0 && !tw.usedBinary { - copy(header[257:265], []byte("ustar\x00")) - } - } - } - } - - // The chksum field is terminated by a NUL and a space. - // This is different from the other octal fields. - chksum, _ := checksum(header) - tw.octal(header[148:155], chksum) - header[155] = ' ' - - if tw.err != nil { - // problem with header; probably integer too big for a field. - return tw.err - } - - if allowPax { - for k, v := range hdr.Xattrs { - paxHeaders[paxXattr+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 -} - -// writeUSTARLongName splits a USTAR long name hdr.Name. -// name must be < 256 characters. errNameTooLong is returned -// if hdr.Name can't be split. The splitting heuristic -// is compatible with gnu tar. -func (tw *Writer) splitUSTARLongName(name string) (prefix, suffix string, err error) { - length := len(name) - if length > fileNamePrefixSize+1 { - length = fileNamePrefixSize + 1 - } else if name[length-1] == '/' { - length-- - } - i := strings.LastIndex(name[:length], "/") - // nlen contains the resulting length in the name field. - // plen contains the resulting length in the prefix field. - nlen := len(name) - i - 1 - plen := i - if i <= 0 || nlen > fileNameSize || nlen == 0 || plen > fileNamePrefixSize { - err = errNameTooLong - return - } - prefix, suffix = name[:i], name[i+1:] - return -} - -// 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. - pid := os.Getpid() - dir, file := path.Split(hdr.Name) - fullName := path.Join(dir, - fmt.Sprintf("PaxHeaders.%d", pid), file) - - ascii := toASCII(fullName) - if len(ascii) > 100 { - ascii = ascii[:100] - } - ext.Name = ascii - // Construct the body - var buf bytes.Buffer - - for k, v := range paxHeaders { - fmt.Fprint(&buf, paxHeader(k+"="+v)) - } - - 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 -} - -// paxHeader formats a single pax record, prefixing it with the appropriate length -func paxHeader(msg string) string { - const padding = 2 // Extra padding for space and newline - size := len(msg) + padding - size += len(strconv.Itoa(size)) - record := fmt.Sprintf("%d %s\n", size, msg) - if len(record) != size { - // Final adjustment if adding size increased - // the number of digits in size - size = len(record) - record = fmt.Sprintf("%d %s\n", size, msg) - } - 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 = ErrWriteTooLong - 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 -} |