// Copyright 2011 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 zip import ( "bufio" "compress/flate" "encoding/binary" "errors" "hash" "hash/crc32" "io" ) // TODO(adg): support zip file comments // TODO(adg): support specifying deflate level // Writer implements a zip file writer. type Writer struct { cw *countWriter dir []*header last *fileWriter closed bool } type header struct { *FileHeader offset uint32 } // NewWriter returns a new Writer writing a zip file to w. func NewWriter(w io.Writer) *Writer { return &Writer{cw: &countWriter{w: bufio.NewWriter(w)}} } // Close finishes writing the zip file by writing the central directory. // It does not (and can not) close the underlying writer. func (w *Writer) Close() error { if w.last != nil && !w.last.closed { if err := w.last.close(); err != nil { return err } w.last = nil } if w.closed { return errors.New("zip: writer closed twice") } w.closed = true // write central directory start := w.cw.count for _, h := range w.dir { var buf [directoryHeaderLen]byte b := writeBuf(buf[:]) b.uint32(uint32(directoryHeaderSignature)) b.uint16(h.CreatorVersion) b.uint16(h.ReaderVersion) b.uint16(h.Flags) b.uint16(h.Method) b.uint16(h.ModifiedTime) b.uint16(h.ModifiedDate) b.uint32(h.CRC32) b.uint32(h.CompressedSize) b.uint32(h.UncompressedSize) b.uint16(uint16(len(h.Name))) b.uint16(uint16(len(h.Extra))) b.uint16(uint16(len(h.Comment))) b = b[4:] // skip disk number start and internal file attr (2x uint16) b.uint32(h.ExternalAttrs) b.uint32(h.offset) if _, err := w.cw.Write(buf[:]); err != nil { return err } if _, err := io.WriteString(w.cw, h.Name); err != nil { return err } if _, err := w.cw.Write(h.Extra); err != nil { return err } if _, err := io.WriteString(w.cw, h.Comment); err != nil { return err } } end := w.cw.count // write end record var buf [directoryEndLen]byte b := writeBuf(buf[:]) b.uint32(uint32(directoryEndSignature)) b = b[4:] // skip over disk number and first disk number (2x uint16) b.uint16(uint16(len(w.dir))) // number of entries this disk b.uint16(uint16(len(w.dir))) // number of entries total b.uint32(uint32(end - start)) // size of directory b.uint32(uint32(start)) // start of directory // skipped size of comment (always zero) if _, err := w.cw.Write(buf[:]); err != nil { return err } return w.cw.w.(*bufio.Writer).Flush() } // Create adds a file to the zip file using the provided name. // It returns a Writer to which the file contents should be written. // The file's contents must be written to the io.Writer before the next // call to Create, CreateHeader, or Close. func (w *Writer) Create(name string) (io.Writer, error) { header := &FileHeader{ Name: name, Method: Deflate, } return w.CreateHeader(header) } // CreateHeader adds a file to the zip file using the provided FileHeader // for the file metadata. // It returns a Writer to which the file contents should be written. // The file's contents must be written to the io.Writer before the next // call to Create, CreateHeader, or Close. func (w *Writer) CreateHeader(fh *FileHeader) (io.Writer, error) { if w.last != nil && !w.last.closed { if err := w.last.close(); err != nil { return nil, err } } fh.Flags |= 0x8 // we will write a data descriptor fh.CreatorVersion = fh.CreatorVersion&0xff00 | 0x14 fh.ReaderVersion = 0x14 fw := &fileWriter{ zipw: w.cw, compCount: &countWriter{w: w.cw}, crc32: crc32.NewIEEE(), } switch fh.Method { case Store: fw.comp = nopCloser{fw.compCount} case Deflate: var err error fw.comp, err = flate.NewWriter(fw.compCount, 5) if err != nil { return nil, err } default: return nil, ErrAlgorithm } fw.rawCount = &countWriter{w: fw.comp} h := &header{ FileHeader: fh, offset: uint32(w.cw.count), } w.dir = append(w.dir, h) fw.header = h if err := writeHeader(w.cw, fh); err != nil { return nil, err } w.last = fw return fw, nil } func writeHeader(w io.Writer, h *FileHeader) error { var buf [fileHeaderLen]byte b := writeBuf(buf[:]) b.uint32(uint32(fileHeaderSignature)) b.uint16(h.ReaderVersion) b.uint16(h.Flags) b.uint16(h.Method) b.uint16(h.ModifiedTime) b.uint16(h.ModifiedDate) b.uint32(h.CRC32) b.uint32(h.CompressedSize) b.uint32(h.UncompressedSize) b.uint16(uint16(len(h.Name))) b.uint16(uint16(len(h.Extra))) if _, err := w.Write(buf[:]); err != nil { return err } if _, err := io.WriteString(w, h.Name); err != nil { return err } _, err := w.Write(h.Extra) return err } type fileWriter struct { *header zipw io.Writer rawCount *countWriter comp io.WriteCloser compCount *countWriter crc32 hash.Hash32 closed bool } func (w *fileWriter) Write(p []byte) (int, error) { if w.closed { return 0, errors.New("zip: write to closed file") } w.crc32.Write(p) return w.rawCount.Write(p) } func (w *fileWriter) close() error { if w.closed { return errors.New("zip: file closed twice") } w.closed = true if err := w.comp.Close(); err != nil { return err } // update FileHeader fh := w.header.FileHeader fh.CRC32 = w.crc32.Sum32() fh.CompressedSize = uint32(w.compCount.count) fh.UncompressedSize = uint32(w.rawCount.count) // write data descriptor var buf [dataDescriptorLen]byte b := writeBuf(buf[:]) b.uint32(dataDescriptorSignature) // de-facto standard, required by OS X b.uint32(fh.CRC32) b.uint32(fh.CompressedSize) b.uint32(fh.UncompressedSize) _, err := w.zipw.Write(buf[:]) return err } type countWriter struct { w io.Writer count int64 } func (w *countWriter) Write(p []byte) (int, error) { n, err := w.w.Write(p) w.count += int64(n) return n, err } type nopCloser struct { io.Writer } func (w nopCloser) Close() error { return nil } type writeBuf []byte func (b *writeBuf) uint16(v uint16) { binary.LittleEndian.PutUint16(*b, v) *b = (*b)[2:] } func (b *writeBuf) uint32(v uint32) { binary.LittleEndian.PutUint32(*b, v) *b = (*b)[4:] }