352 lines
9.2 KiB
Go
352 lines
9.2 KiB
Go
// Copyright 2011 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 zip
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import (
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"bufio"
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"encoding/binary"
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"errors"
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"hash"
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"hash/crc32"
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"io"
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)
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// TODO(adg): support zip file comments
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// TODO(adg): support specifying deflate level
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// Writer implements a zip file writer.
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type Writer struct {
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cw *countWriter
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dir []*header
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last *fileWriter
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closed bool
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}
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type header struct {
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*FileHeader
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offset uint64
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}
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// NewWriter returns a new Writer writing a zip file to w.
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func NewWriter(w io.Writer) *Writer {
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return &Writer{cw: &countWriter{w: bufio.NewWriter(w)}}
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}
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// Close finishes writing the zip file by writing the central directory.
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// It does not (and can not) close the underlying writer.
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func (w *Writer) Close() error {
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if w.last != nil && !w.last.closed {
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if err := w.last.close(); err != nil {
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return err
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}
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w.last = nil
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}
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if w.closed {
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return errors.New("zip: writer closed twice")
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}
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w.closed = true
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// write central directory
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start := w.cw.count
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for _, h := range w.dir {
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var buf [directoryHeaderLen]byte
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b := writeBuf(buf[:])
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b.uint32(uint32(directoryHeaderSignature))
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b.uint16(h.CreatorVersion)
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b.uint16(h.ReaderVersion)
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b.uint16(h.Flags)
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b.uint16(h.Method)
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b.uint16(h.ModifiedTime)
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b.uint16(h.ModifiedDate)
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b.uint32(h.CRC32)
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if h.isZip64() || h.offset > uint32max {
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// the file needs a zip64 header. store maxint in both
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// 32 bit size fields (and offset later) to signal that the
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// zip64 extra header should be used.
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b.uint32(uint32max) // compressed size
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b.uint32(uint32max) // uncompressed size
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// append a zip64 extra block to Extra
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var buf [28]byte // 2x uint16 + 3x uint64
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eb := writeBuf(buf[:])
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eb.uint16(zip64ExtraId)
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eb.uint16(24) // size = 3x uint64
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eb.uint64(h.UncompressedSize64)
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eb.uint64(h.CompressedSize64)
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eb.uint64(h.offset)
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h.Extra = append(h.Extra, buf[:]...)
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} else {
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b.uint32(h.CompressedSize)
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b.uint32(h.UncompressedSize)
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}
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b.uint16(uint16(len(h.Name)))
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b.uint16(uint16(len(h.Extra)))
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b.uint16(uint16(len(h.Comment)))
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b = b[4:] // skip disk number start and internal file attr (2x uint16)
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b.uint32(h.ExternalAttrs)
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if h.offset > uint32max {
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b.uint32(uint32max)
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} else {
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b.uint32(uint32(h.offset))
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}
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if _, err := w.cw.Write(buf[:]); err != nil {
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return err
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}
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if _, err := io.WriteString(w.cw, h.Name); err != nil {
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return err
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}
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if _, err := w.cw.Write(h.Extra); err != nil {
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return err
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}
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if _, err := io.WriteString(w.cw, h.Comment); err != nil {
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return err
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}
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}
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end := w.cw.count
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records := uint64(len(w.dir))
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size := uint64(end - start)
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offset := uint64(start)
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if records > uint16max || size > uint32max || offset > uint32max {
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var buf [directory64EndLen + directory64LocLen]byte
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b := writeBuf(buf[:])
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// zip64 end of central directory record
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b.uint32(directory64EndSignature)
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b.uint64(directory64EndLen)
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b.uint16(zipVersion45) // version made by
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b.uint16(zipVersion45) // version needed to extract
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b.uint32(0) // number of this disk
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b.uint32(0) // number of the disk with the start of the central directory
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b.uint64(records) // total number of entries in the central directory on this disk
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b.uint64(records) // total number of entries in the central directory
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b.uint64(size) // size of the central directory
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b.uint64(offset) // offset of start of central directory with respect to the starting disk number
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// zip64 end of central directory locator
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b.uint32(directory64LocSignature)
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b.uint32(0) // number of the disk with the start of the zip64 end of central directory
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b.uint64(uint64(end)) // relative offset of the zip64 end of central directory record
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b.uint32(1) // total number of disks
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if _, err := w.cw.Write(buf[:]); err != nil {
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return err
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}
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// store max values in the regular end record to signal that
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// that the zip64 values should be used instead
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records = uint16max
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size = uint32max
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offset = uint32max
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}
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// write end record
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var buf [directoryEndLen]byte
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b := writeBuf(buf[:])
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b.uint32(uint32(directoryEndSignature))
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b = b[4:] // skip over disk number and first disk number (2x uint16)
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b.uint16(uint16(records)) // number of entries this disk
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b.uint16(uint16(records)) // number of entries total
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b.uint32(uint32(size)) // size of directory
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b.uint32(uint32(offset)) // start of directory
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// skipped size of comment (always zero)
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if _, err := w.cw.Write(buf[:]); err != nil {
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return err
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}
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return w.cw.w.(*bufio.Writer).Flush()
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}
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// Create adds a file to the zip file using the provided name.
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// It returns a Writer to which the file contents should be written.
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// The name must be a relative path: it must not start with a drive
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// letter (e.g. C:) or leading slash, and only forward slashes are
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// allowed.
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// The file's contents must be written to the io.Writer before the next
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// call to Create, CreateHeader, or Close.
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func (w *Writer) Create(name string) (io.Writer, error) {
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header := &FileHeader{
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Name: name,
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Method: Deflate,
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}
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return w.CreateHeader(header)
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}
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// CreateHeader adds a file to the zip file using the provided FileHeader
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// for the file metadata.
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// It returns a Writer to which the file contents should be written.
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// The file's contents must be written to the io.Writer before the next
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// call to Create, CreateHeader, or Close.
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func (w *Writer) CreateHeader(fh *FileHeader) (io.Writer, error) {
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if w.last != nil && !w.last.closed {
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if err := w.last.close(); err != nil {
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return nil, err
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}
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}
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fh.Flags |= 0x8 // we will write a data descriptor
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fh.CreatorVersion = fh.CreatorVersion&0xff00 | zipVersion20 // preserve compatibility byte
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fh.ReaderVersion = zipVersion20
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fw := &fileWriter{
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zipw: w.cw,
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compCount: &countWriter{w: w.cw},
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crc32: crc32.NewIEEE(),
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}
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comp := compressor(fh.Method)
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if comp == nil {
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return nil, ErrAlgorithm
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}
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var err error
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fw.comp, err = comp(fw.compCount)
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if err != nil {
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return nil, err
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}
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fw.rawCount = &countWriter{w: fw.comp}
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h := &header{
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FileHeader: fh,
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offset: uint64(w.cw.count),
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}
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w.dir = append(w.dir, h)
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fw.header = h
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if err := writeHeader(w.cw, fh); err != nil {
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return nil, err
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}
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w.last = fw
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return fw, nil
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}
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func writeHeader(w io.Writer, h *FileHeader) error {
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var buf [fileHeaderLen]byte
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b := writeBuf(buf[:])
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b.uint32(uint32(fileHeaderSignature))
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b.uint16(h.ReaderVersion)
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b.uint16(h.Flags)
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b.uint16(h.Method)
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b.uint16(h.ModifiedTime)
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b.uint16(h.ModifiedDate)
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b.uint32(0) // since we are writing a data descriptor crc32,
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b.uint32(0) // compressed size,
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b.uint32(0) // and uncompressed size should be zero
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b.uint16(uint16(len(h.Name)))
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b.uint16(uint16(len(h.Extra)))
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if _, err := w.Write(buf[:]); err != nil {
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return err
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}
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if _, err := io.WriteString(w, h.Name); err != nil {
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return err
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}
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_, err := w.Write(h.Extra)
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return err
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}
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type fileWriter struct {
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*header
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zipw io.Writer
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rawCount *countWriter
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comp io.WriteCloser
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compCount *countWriter
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crc32 hash.Hash32
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closed bool
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}
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func (w *fileWriter) Write(p []byte) (int, error) {
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if w.closed {
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return 0, errors.New("zip: write to closed file")
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}
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w.crc32.Write(p)
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return w.rawCount.Write(p)
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}
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func (w *fileWriter) close() error {
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if w.closed {
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return errors.New("zip: file closed twice")
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}
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w.closed = true
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if err := w.comp.Close(); err != nil {
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return err
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}
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// update FileHeader
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fh := w.header.FileHeader
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fh.CRC32 = w.crc32.Sum32()
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fh.CompressedSize64 = uint64(w.compCount.count)
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fh.UncompressedSize64 = uint64(w.rawCount.count)
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if fh.isZip64() {
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fh.CompressedSize = uint32max
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fh.UncompressedSize = uint32max
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fh.ReaderVersion = zipVersion45 // requires 4.5 - File uses ZIP64 format extensions
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} else {
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fh.CompressedSize = uint32(fh.CompressedSize64)
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fh.UncompressedSize = uint32(fh.UncompressedSize64)
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}
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// Write data descriptor. This is more complicated than one would
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// think, see e.g. comments in zipfile.c:putextended() and
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// http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7073588.
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// The approach here is to write 8 byte sizes if needed without
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// adding a zip64 extra in the local header (too late anyway).
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var buf []byte
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if fh.isZip64() {
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buf = make([]byte, dataDescriptor64Len)
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} else {
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buf = make([]byte, dataDescriptorLen)
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}
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b := writeBuf(buf)
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b.uint32(dataDescriptorSignature) // de-facto standard, required by OS X
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b.uint32(fh.CRC32)
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if fh.isZip64() {
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b.uint64(fh.CompressedSize64)
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b.uint64(fh.UncompressedSize64)
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} else {
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b.uint32(fh.CompressedSize)
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b.uint32(fh.UncompressedSize)
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}
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_, err := w.zipw.Write(buf)
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return err
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}
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type countWriter struct {
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w io.Writer
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count int64
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}
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func (w *countWriter) Write(p []byte) (int, error) {
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n, err := w.w.Write(p)
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w.count += int64(n)
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return n, err
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}
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type nopCloser struct {
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io.Writer
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}
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func (w nopCloser) Close() error {
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return nil
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}
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type writeBuf []byte
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func (b *writeBuf) uint16(v uint16) {
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binary.LittleEndian.PutUint16(*b, v)
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*b = (*b)[2:]
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}
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func (b *writeBuf) uint32(v uint32) {
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binary.LittleEndian.PutUint32(*b, v)
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*b = (*b)[4:]
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}
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func (b *writeBuf) uint64(v uint64) {
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binary.LittleEndian.PutUint64(*b, v)
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*b = (*b)[8:]
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}
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