diff options
Diffstat (limited to 'src/archive/zip/writer.go')
| -rw-r--r-- | src/archive/zip/writer.go | 634 |
1 files changed, 634 insertions, 0 deletions
diff --git a/src/archive/zip/writer.go b/src/archive/zip/writer.go new file mode 100644 index 0000000..3b23cc3 --- /dev/null +++ b/src/archive/zip/writer.go @@ -0,0 +1,634 @@ +// 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" + "encoding/binary" + "errors" + "hash" + "hash/crc32" + "io" + "strings" + "unicode/utf8" +) + +var ( + errLongName = errors.New("zip: FileHeader.Name too long") + errLongExtra = errors.New("zip: FileHeader.Extra too long") +) + +// Writer implements a zip file writer. +type Writer struct { + cw *countWriter + dir []*header + last *fileWriter + closed bool + compressors map[uint16]Compressor + comment string + + // testHookCloseSizeOffset if non-nil is called with the size + // of offset of the central directory at Close. + testHookCloseSizeOffset func(size, offset uint64) +} + +type header struct { + *FileHeader + offset uint64 + raw bool +} + +// 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)}} +} + +// SetOffset sets the offset of the beginning of the zip data within the +// underlying writer. It should be used when the zip data is appended to an +// existing file, such as a binary executable. +// It must be called before any data is written. +func (w *Writer) SetOffset(n int64) { + if w.cw.count != 0 { + panic("zip: SetOffset called after data was written") + } + w.cw.count = n +} + +// Flush flushes any buffered data to the underlying writer. +// Calling Flush is not normally necessary; calling Close is sufficient. +func (w *Writer) Flush() error { + return w.cw.w.(*bufio.Writer).Flush() +} + +// SetComment sets the end-of-central-directory comment field. +// It can only be called before Close. +func (w *Writer) SetComment(comment string) error { + if len(comment) > uint16max { + return errors.New("zip: Writer.Comment too long") + } + w.comment = comment + return nil +} + +// Close finishes writing the zip file by writing the central directory. +// It does 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) + if h.isZip64() || h.offset >= uint32max { + // the file needs a zip64 header. store maxint in both + // 32 bit size fields (and offset later) to signal that the + // zip64 extra header should be used. + b.uint32(uint32max) // compressed size + b.uint32(uint32max) // uncompressed size + + // append a zip64 extra block to Extra + var buf [28]byte // 2x uint16 + 3x uint64 + eb := writeBuf(buf[:]) + eb.uint16(zip64ExtraID) + eb.uint16(24) // size = 3x uint64 + eb.uint64(h.UncompressedSize64) + eb.uint64(h.CompressedSize64) + eb.uint64(h.offset) + h.Extra = append(h.Extra, buf[:]...) + } else { + 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) + if h.offset > uint32max { + b.uint32(uint32max) + } else { + b.uint32(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 + + records := uint64(len(w.dir)) + size := uint64(end - start) + offset := uint64(start) + + if f := w.testHookCloseSizeOffset; f != nil { + f(size, offset) + } + + if records >= uint16max || size >= uint32max || offset >= uint32max { + var buf [directory64EndLen + directory64LocLen]byte + b := writeBuf(buf[:]) + + // zip64 end of central directory record + b.uint32(directory64EndSignature) + b.uint64(directory64EndLen - 12) // length minus signature (uint32) and length fields (uint64) + b.uint16(zipVersion45) // version made by + b.uint16(zipVersion45) // version needed to extract + b.uint32(0) // number of this disk + b.uint32(0) // number of the disk with the start of the central directory + b.uint64(records) // total number of entries in the central directory on this disk + b.uint64(records) // total number of entries in the central directory + b.uint64(size) // size of the central directory + b.uint64(offset) // offset of start of central directory with respect to the starting disk number + + // zip64 end of central directory locator + b.uint32(directory64LocSignature) + b.uint32(0) // number of the disk with the start of the zip64 end of central directory + b.uint64(uint64(end)) // relative offset of the zip64 end of central directory record + b.uint32(1) // total number of disks + + if _, err := w.cw.Write(buf[:]); err != nil { + return err + } + + // store max values in the regular end record to signal + // that the zip64 values should be used instead + records = uint16max + size = uint32max + offset = uint32max + } + + // 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(records)) // number of entries this disk + b.uint16(uint16(records)) // number of entries total + b.uint32(uint32(size)) // size of directory + b.uint32(uint32(offset)) // start of directory + b.uint16(uint16(len(w.comment))) // byte size of EOCD comment + if _, err := w.cw.Write(buf[:]); err != nil { + return err + } + if _, err := io.WriteString(w.cw, w.comment); 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 contents will be compressed using the Deflate method. +// The name must be a relative path: it must not start with a drive +// letter (e.g. C:) or leading slash, and only forward slashes are +// allowed. To create a directory instead of a file, add a trailing +// slash to the name. +// 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) +} + +// detectUTF8 reports whether s is a valid UTF-8 string, and whether the string +// must be considered UTF-8 encoding (i.e., not compatible with CP-437, ASCII, +// or any other common encoding). +func detectUTF8(s string) (valid, require bool) { + for i := 0; i < len(s); { + r, size := utf8.DecodeRuneInString(s[i:]) + i += size + // Officially, ZIP uses CP-437, but many readers use the system's + // local character encoding. Most encoding are compatible with a large + // subset of CP-437, which itself is ASCII-like. + // + // Forbid 0x7e and 0x5c since EUC-KR and Shift-JIS replace those + // characters with localized currency and overline characters. + if r < 0x20 || r > 0x7d || r == 0x5c { + if !utf8.ValidRune(r) || (r == utf8.RuneError && size == 1) { + return false, false + } + require = true + } + } + return true, require +} + +// prepare performs the bookkeeping operations required at the start of +// CreateHeader and CreateRaw. +func (w *Writer) prepare(fh *FileHeader) error { + if w.last != nil && !w.last.closed { + if err := w.last.close(); err != nil { + return err + } + } + if len(w.dir) > 0 && w.dir[len(w.dir)-1].FileHeader == fh { + // See https://golang.org/issue/11144 confusion. + return errors.New("archive/zip: invalid duplicate FileHeader") + } + return nil +} + +// CreateHeader adds a file to the zip archive using the provided FileHeader +// for the file metadata. Writer takes ownership of fh and may mutate +// its fields. The caller must not modify fh after calling CreateHeader. +// +// This 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, CreateRaw, or Close. +func (w *Writer) CreateHeader(fh *FileHeader) (io.Writer, error) { + if err := w.prepare(fh); err != nil { + return nil, err + } + + // The ZIP format has a sad state of affairs regarding character encoding. + // Officially, the name and comment fields are supposed to be encoded + // in CP-437 (which is mostly compatible with ASCII), unless the UTF-8 + // flag bit is set. However, there are several problems: + // + // * Many ZIP readers still do not support UTF-8. + // * If the UTF-8 flag is cleared, several readers simply interpret the + // name and comment fields as whatever the local system encoding is. + // + // In order to avoid breaking readers without UTF-8 support, + // we avoid setting the UTF-8 flag if the strings are CP-437 compatible. + // However, if the strings require multibyte UTF-8 encoding and is a + // valid UTF-8 string, then we set the UTF-8 bit. + // + // For the case, where the user explicitly wants to specify the encoding + // as UTF-8, they will need to set the flag bit themselves. + utf8Valid1, utf8Require1 := detectUTF8(fh.Name) + utf8Valid2, utf8Require2 := detectUTF8(fh.Comment) + switch { + case fh.NonUTF8: + fh.Flags &^= 0x800 + case (utf8Require1 || utf8Require2) && (utf8Valid1 && utf8Valid2): + fh.Flags |= 0x800 + } + + fh.CreatorVersion = fh.CreatorVersion&0xff00 | zipVersion20 // preserve compatibility byte + fh.ReaderVersion = zipVersion20 + + // If Modified is set, this takes precedence over MS-DOS timestamp fields. + if !fh.Modified.IsZero() { + // Contrary to the FileHeader.SetModTime method, we intentionally + // do not convert to UTC, because we assume the user intends to encode + // the date using the specified timezone. A user may want this control + // because many legacy ZIP readers interpret the timestamp according + // to the local timezone. + // + // The timezone is only non-UTC if a user directly sets the Modified + // field directly themselves. All other approaches sets UTC. + fh.ModifiedDate, fh.ModifiedTime = timeToMsDosTime(fh.Modified) + + // Use "extended timestamp" format since this is what Info-ZIP uses. + // Nearly every major ZIP implementation uses a different format, + // but at least most seem to be able to understand the other formats. + // + // This format happens to be identical for both local and central header + // if modification time is the only timestamp being encoded. + var mbuf [9]byte // 2*SizeOf(uint16) + SizeOf(uint8) + SizeOf(uint32) + mt := uint32(fh.Modified.Unix()) + eb := writeBuf(mbuf[:]) + eb.uint16(extTimeExtraID) + eb.uint16(5) // Size: SizeOf(uint8) + SizeOf(uint32) + eb.uint8(1) // Flags: ModTime + eb.uint32(mt) // ModTime + fh.Extra = append(fh.Extra, mbuf[:]...) + } + + var ( + ow io.Writer + fw *fileWriter + ) + h := &header{ + FileHeader: fh, + offset: uint64(w.cw.count), + } + + if strings.HasSuffix(fh.Name, "/") { + // Set the compression method to Store to ensure data length is truly zero, + // which the writeHeader method always encodes for the size fields. + // This is necessary as most compression formats have non-zero lengths + // even when compressing an empty string. + fh.Method = Store + fh.Flags &^= 0x8 // we will not write a data descriptor + + // Explicitly clear sizes as they have no meaning for directories. + fh.CompressedSize = 0 + fh.CompressedSize64 = 0 + fh.UncompressedSize = 0 + fh.UncompressedSize64 = 0 + + ow = dirWriter{} + } else { + fh.Flags |= 0x8 // we will write a data descriptor + + fw = &fileWriter{ + zipw: w.cw, + compCount: &countWriter{w: w.cw}, + crc32: crc32.NewIEEE(), + } + comp := w.compressor(fh.Method) + if comp == nil { + return nil, ErrAlgorithm + } + var err error + fw.comp, err = comp(fw.compCount) + if err != nil { + return nil, err + } + fw.rawCount = &countWriter{w: fw.comp} + fw.header = h + ow = fw + } + w.dir = append(w.dir, h) + if err := writeHeader(w.cw, h); err != nil { + return nil, err + } + // If we're creating a directory, fw is nil. + w.last = fw + return ow, nil +} + +func writeHeader(w io.Writer, h *header) error { + const maxUint16 = 1<<16 - 1 + if len(h.Name) > maxUint16 { + return errLongName + } + if len(h.Extra) > maxUint16 { + return errLongExtra + } + + 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) + // In raw mode (caller does the compression), the values are either + // written here or in the trailing data descriptor based on the header + // flags. + if h.raw && !h.hasDataDescriptor() { + b.uint32(h.CRC32) + b.uint32(uint32(min64(h.CompressedSize64, uint32max))) + b.uint32(uint32(min64(h.UncompressedSize64, uint32max))) + } else { + // When this package handle the compression, these values are + // always written to the trailing data descriptor. + b.uint32(0) // crc32 + b.uint32(0) // compressed size + b.uint32(0) // uncompressed size + } + 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 +} + +func min64(x, y uint64) uint64 { + if x < y { + return x + } + return y +} + +// CreateRaw adds a file to the zip archive using the provided FileHeader and +// 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, CreateRaw, or Close. +// +// In contrast to CreateHeader, the bytes passed to Writer are not compressed. +func (w *Writer) CreateRaw(fh *FileHeader) (io.Writer, error) { + if err := w.prepare(fh); err != nil { + return nil, err + } + + fh.CompressedSize = uint32(min64(fh.CompressedSize64, uint32max)) + fh.UncompressedSize = uint32(min64(fh.UncompressedSize64, uint32max)) + + h := &header{ + FileHeader: fh, + offset: uint64(w.cw.count), + raw: true, + } + w.dir = append(w.dir, h) + if err := writeHeader(w.cw, h); err != nil { + return nil, err + } + + if strings.HasSuffix(fh.Name, "/") { + w.last = nil + return dirWriter{}, nil + } + + fw := &fileWriter{ + header: h, + zipw: w.cw, + } + w.last = fw + return fw, nil +} + +// Copy copies the file f (obtained from a Reader) into w. It copies the raw +// form directly bypassing decompression, compression, and validation. +func (w *Writer) Copy(f *File) error { + r, err := f.OpenRaw() + if err != nil { + return err + } + fw, err := w.CreateRaw(&f.FileHeader) + if err != nil { + return err + } + _, err = io.Copy(fw, r) + return err +} + +// RegisterCompressor registers or overrides a custom compressor for a specific +// method ID. If a compressor for a given method is not found, Writer will +// default to looking up the compressor at the package level. +func (w *Writer) RegisterCompressor(method uint16, comp Compressor) { + if w.compressors == nil { + w.compressors = make(map[uint16]Compressor) + } + w.compressors[method] = comp +} + +func (w *Writer) compressor(method uint16) Compressor { + comp := w.compressors[method] + if comp == nil { + comp = compressor(method) + } + return comp +} + +type dirWriter struct{} + +func (dirWriter) Write(b []byte) (int, error) { + if len(b) == 0 { + return 0, nil + } + return 0, errors.New("zip: write to directory") +} + +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") + } + if w.raw { + return w.zipw.Write(p) + } + 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 w.raw { + return w.writeDataDescriptor() + } + if err := w.comp.Close(); err != nil { + return err + } + + // update FileHeader + fh := w.header.FileHeader + fh.CRC32 = w.crc32.Sum32() + fh.CompressedSize64 = uint64(w.compCount.count) + fh.UncompressedSize64 = uint64(w.rawCount.count) + + if fh.isZip64() { + fh.CompressedSize = uint32max + fh.UncompressedSize = uint32max + fh.ReaderVersion = zipVersion45 // requires 4.5 - File uses ZIP64 format extensions + } else { + fh.CompressedSize = uint32(fh.CompressedSize64) + fh.UncompressedSize = uint32(fh.UncompressedSize64) + } + + return w.writeDataDescriptor() +} + +func (w *fileWriter) writeDataDescriptor() error { + if !w.hasDataDescriptor() { + return nil + } + // Write data descriptor. This is more complicated than one would + // think, see e.g. comments in zipfile.c:putextended() and + // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7073588. + // The approach here is to write 8 byte sizes if needed without + // adding a zip64 extra in the local header (too late anyway). + var buf []byte + if w.isZip64() { + buf = make([]byte, dataDescriptor64Len) + } else { + buf = make([]byte, dataDescriptorLen) + } + b := writeBuf(buf) + b.uint32(dataDescriptorSignature) // de-facto standard, required by OS X + b.uint32(w.CRC32) + if w.isZip64() { + b.uint64(w.CompressedSize64) + b.uint64(w.UncompressedSize64) + } else { + b.uint32(w.CompressedSize) + b.uint32(w.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) uint8(v uint8) { + (*b)[0] = v + *b = (*b)[1:] +} + +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:] +} + +func (b *writeBuf) uint64(v uint64) { + binary.LittleEndian.PutUint64(*b, v) + *b = (*b)[8:] +} |