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archive/zip: more efficient reader and bug fix
Fixes #2090. R=golang-dev, bradfitz CC=golang-dev https://golang.org/cl/4815068
This commit is contained in:
Andrew Gerrand
parent
60dac9b3db
commit
e0b6f4721f
@ -6,7 +6,6 @@ package zip
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import (
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"bufio"
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"bytes"
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"compress/flate"
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"hash"
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"hash/crc32"
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@ -37,8 +36,7 @@ type File struct {
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FileHeader
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zipr io.ReaderAt
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zipsize int64
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headerOffset uint32
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bodyOffset int64
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headerOffset int64
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}
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func (f *File) hasDataDescriptor() bool {
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@ -90,12 +88,12 @@ func (z *Reader) init(r io.ReaderAt, size int64) os.Error {
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// The count of files inside a zip is truncated to fit in a uint16.
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// Gloss over this by reading headers until we encounter
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// a bad one, and then only report a FormatError if
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// a bad one, and then only report a FormatError or UnexpectedEOF if
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// the file count modulo 65536 is incorrect.
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for {
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f := &File{zipr: r, zipsize: size}
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err := readDirectoryHeader(f, buf)
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if err == FormatError {
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err = readDirectoryHeader(f, buf)
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if err == FormatError || err == io.ErrUnexpectedEOF {
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break
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}
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if err != nil {
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@ -104,9 +102,10 @@ func (z *Reader) init(r io.ReaderAt, size int64) os.Error {
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z.File = append(z.File, f)
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}
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if uint16(len(z.File)) != end.directoryRecords {
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return FormatError
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// Return the readDirectoryHeader error if we read
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// the wrong number of directory entries.
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return err
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}
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return nil
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}
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@ -116,26 +115,18 @@ func (rc *ReadCloser) Close() os.Error {
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}
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// Open returns a ReadCloser that provides access to the File's contents.
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// It is safe to Open and Read from files concurrently.
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func (f *File) Open() (rc io.ReadCloser, err os.Error) {
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off := int64(f.headerOffset)
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bodyOffset, err := f.findBodyOffset()
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if err != nil {
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return
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}
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size := int64(f.CompressedSize)
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if f.bodyOffset == 0 {
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r := io.NewSectionReader(f.zipr, off, f.zipsize-off)
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if err = readFileHeader(f, r); err != nil {
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return
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}
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if f.bodyOffset, err = r.Seek(0, os.SEEK_CUR); err != nil {
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return
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}
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if size == 0 {
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size = int64(f.CompressedSize)
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}
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}
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if f.hasDataDescriptor() && size == 0 {
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if size == 0 && f.hasDataDescriptor() {
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// permit SectionReader to see the rest of the file
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size = f.zipsize - (off + f.bodyOffset)
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size = f.zipsize - (f.headerOffset + bodyOffset)
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}
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r := io.NewSectionReader(f.zipr, off+f.bodyOffset, size)
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r := io.NewSectionReader(f.zipr, f.headerOffset+bodyOffset, size)
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switch f.Method {
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case Store: // (no compression)
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rc = ioutil.NopCloser(r)
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@ -176,75 +167,99 @@ func (r *checksumReader) Read(b []byte) (n int, err os.Error) {
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func (r *checksumReader) Close() os.Error { return r.rc.Close() }
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func readFileHeader(f *File, r io.Reader) (err os.Error) {
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defer recoverError(&err)
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var (
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signature uint32
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filenameLength uint16
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extraLength uint16
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)
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read(r, &signature)
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if signature != fileHeaderSignature {
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func readFileHeader(f *File, r io.Reader) os.Error {
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var b [fileHeaderLen]byte
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if _, err := io.ReadFull(r, b[:]); err != nil {
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return err
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}
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c := binary.LittleEndian
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if sig := c.Uint32(b[:4]); sig != fileHeaderSignature {
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return FormatError
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}
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read(r, &f.ReaderVersion)
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read(r, &f.Flags)
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read(r, &f.Method)
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read(r, &f.ModifiedTime)
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read(r, &f.ModifiedDate)
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read(r, &f.CRC32)
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read(r, &f.CompressedSize)
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read(r, &f.UncompressedSize)
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read(r, &filenameLength)
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read(r, &extraLength)
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f.Name = string(readByteSlice(r, filenameLength))
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f.Extra = readByteSlice(r, extraLength)
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return
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f.ReaderVersion = c.Uint16(b[4:6])
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f.Flags = c.Uint16(b[6:8])
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f.Method = c.Uint16(b[8:10])
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f.ModifiedTime = c.Uint16(b[10:12])
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f.ModifiedDate = c.Uint16(b[12:14])
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f.CRC32 = c.Uint32(b[14:18])
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f.CompressedSize = c.Uint32(b[18:22])
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f.UncompressedSize = c.Uint32(b[22:26])
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filenameLen := int(c.Uint16(b[26:28]))
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extraLen := int(c.Uint16(b[28:30]))
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d := make([]byte, filenameLen+extraLen)
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if _, err := io.ReadFull(r, d); err != nil {
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return err
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}
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f.Name = string(d[:filenameLen])
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f.Extra = d[filenameLen:]
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return nil
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}
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func readDirectoryHeader(f *File, r io.Reader) (err os.Error) {
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defer recoverError(&err)
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var (
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signature uint32
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filenameLength uint16
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extraLength uint16
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commentLength uint16
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startDiskNumber uint16 // unused
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internalAttributes uint16 // unused
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externalAttributes uint32 // unused
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)
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read(r, &signature)
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if signature != directoryHeaderSignature {
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// findBodyOffset does the minimum work to verify the file has a header
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// and returns the file body offset.
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func (f *File) findBodyOffset() (int64, os.Error) {
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r := io.NewSectionReader(f.zipr, f.headerOffset, f.zipsize-f.headerOffset)
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var b [fileHeaderLen]byte
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if _, err := io.ReadFull(r, b[:]); err != nil {
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return 0, err
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}
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c := binary.LittleEndian
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if sig := c.Uint32(b[:4]); sig != fileHeaderSignature {
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return 0, FormatError
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}
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filenameLen := int(c.Uint16(b[26:28]))
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extraLen := int(c.Uint16(b[28:30]))
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return int64(fileHeaderLen + filenameLen + extraLen), nil
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}
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// readDirectoryHeader attempts to read a directory header from r.
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// It returns io.ErrUnexpectedEOF if it cannot read a complete header,
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// and FormatError if it doesn't find a valid header signature.
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func readDirectoryHeader(f *File, r io.Reader) os.Error {
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var b [directoryHeaderLen]byte
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if _, err := io.ReadFull(r, b[:]); err != nil {
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return err
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}
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c := binary.LittleEndian
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if sig := c.Uint32(b[:4]); sig != directoryHeaderSignature {
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return FormatError
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}
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read(r, &f.CreatorVersion)
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read(r, &f.ReaderVersion)
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read(r, &f.Flags)
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read(r, &f.Method)
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read(r, &f.ModifiedTime)
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read(r, &f.ModifiedDate)
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read(r, &f.CRC32)
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read(r, &f.CompressedSize)
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read(r, &f.UncompressedSize)
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read(r, &filenameLength)
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read(r, &extraLength)
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read(r, &commentLength)
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read(r, &startDiskNumber)
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read(r, &internalAttributes)
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read(r, &externalAttributes)
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read(r, &f.headerOffset)
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f.Name = string(readByteSlice(r, filenameLength))
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f.Extra = readByteSlice(r, extraLength)
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f.Comment = string(readByteSlice(r, commentLength))
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return
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f.CreatorVersion = c.Uint16(b[4:6])
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f.ReaderVersion = c.Uint16(b[6:8])
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f.Flags = c.Uint16(b[8:10])
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f.Method = c.Uint16(b[10:12])
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f.ModifiedTime = c.Uint16(b[12:14])
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f.ModifiedDate = c.Uint16(b[14:16])
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f.CRC32 = c.Uint32(b[16:20])
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f.CompressedSize = c.Uint32(b[20:24])
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f.UncompressedSize = c.Uint32(b[24:28])
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filenameLen := int(c.Uint16(b[28:30]))
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extraLen := int(c.Uint16(b[30:32]))
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commentLen := int(c.Uint16(b[32:34]))
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// startDiskNumber := c.Uint16(b[34:36]) // Unused
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// internalAttributes := c.Uint16(b[36:38]) // Unused
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// externalAttributes := c.Uint32(b[38:42]) // Unused
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f.headerOffset = int64(c.Uint32(b[42:46]))
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d := make([]byte, filenameLen+extraLen+commentLen)
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if _, err := io.ReadFull(r, d); err != nil {
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return err
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}
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f.Name = string(d[:filenameLen])
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f.Extra = d[filenameLen : filenameLen+extraLen]
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f.Comment = string(d[filenameLen+extraLen:])
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return nil
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}
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func readDataDescriptor(r io.Reader, f *File) (err os.Error) {
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defer recoverError(&err)
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read(r, &f.CRC32)
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read(r, &f.CompressedSize)
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read(r, &f.UncompressedSize)
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return
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func readDataDescriptor(r io.Reader, f *File) os.Error {
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var b [dataDescriptorLen]byte
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if _, err := io.ReadFull(r, b[:]); err != nil {
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return err
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}
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c := binary.LittleEndian
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f.CRC32 = c.Uint32(b[:4])
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f.CompressedSize = c.Uint32(b[4:8])
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f.UncompressedSize = c.Uint32(b[8:12])
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return nil
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}
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func readDirectoryEnd(r io.ReaderAt, size int64) (dir *directoryEnd, err os.Error) {
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@ -268,48 +283,29 @@ func readDirectoryEnd(r io.ReaderAt, size int64) (dir *directoryEnd, err os.Erro
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}
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// read header into struct
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defer recoverError(&err)
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br := bytes.NewBuffer(b[4:]) // skip over signature
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c := binary.LittleEndian
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d := new(directoryEnd)
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read(br, &d.diskNbr)
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read(br, &d.dirDiskNbr)
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read(br, &d.dirRecordsThisDisk)
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read(br, &d.directoryRecords)
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read(br, &d.directorySize)
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read(br, &d.directoryOffset)
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read(br, &d.commentLen)
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d.comment = string(readByteSlice(br, d.commentLen))
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d.diskNbr = c.Uint16(b[4:6])
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d.dirDiskNbr = c.Uint16(b[6:8])
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d.dirRecordsThisDisk = c.Uint16(b[8:10])
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d.directoryRecords = c.Uint16(b[10:12])
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d.directorySize = c.Uint32(b[12:16])
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d.directoryOffset = c.Uint32(b[16:20])
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d.commentLen = c.Uint16(b[20:22])
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d.comment = string(b[22 : 22+int(d.commentLen)])
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return d, nil
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}
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func findSignatureInBlock(b []byte) int {
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const minSize = 4 + 2 + 2 + 2 + 2 + 4 + 4 + 2 // fixed part of header
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for i := len(b) - minSize; i >= 0; i-- {
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for i := len(b) - directoryEndLen; i >= 0; i-- {
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// defined from directoryEndSignature in struct.go
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if b[i] == 'P' && b[i+1] == 'K' && b[i+2] == 0x05 && b[i+3] == 0x06 {
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// n is length of comment
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n := int(b[i+minSize-2]) | int(b[i+minSize-1])<<8
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if n+minSize+i == len(b) {
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n := int(b[i+directoryEndLen-2]) | int(b[i+directoryEndLen-1])<<8
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if n+directoryEndLen+i == len(b) {
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return i
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}
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}
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}
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return -1
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}
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func read(r io.Reader, data interface{}) {
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if err := binary.Read(r, binary.LittleEndian, data); err != nil {
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panic(err)
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}
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}
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func readByteSlice(r io.Reader, l uint16) []byte {
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b := make([]byte, l)
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if l == 0 {
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return b
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}
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if _, err := io.ReadFull(r, b); err != nil {
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panic(err)
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}
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return b
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}
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@ -162,6 +162,8 @@ func readTestFile(t *testing.T, ft ZipTestFile, f *File) {
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t.Errorf("%s: mtime=%s (%d); want %s (%d)", f.Name, time.SecondsToUTC(got), got, mtime, want)
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}
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size0 := f.UncompressedSize
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var b bytes.Buffer
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r, err := f.Open()
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if err != nil {
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@ -169,6 +171,10 @@ func readTestFile(t *testing.T, ft ZipTestFile, f *File) {
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return
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}
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if size1 := f.UncompressedSize; size0 != size1 {
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t.Errorf("file %q changed f.UncompressedSize from %d to %d", f.Name, size0, size1)
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}
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_, err = io.Copy(&b, r)
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if err != nil {
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t.Error(err)
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@ -24,6 +24,9 @@ const (
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fileHeaderSignature = 0x04034b50
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directoryHeaderSignature = 0x02014b50
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directoryEndSignature = 0x06054b50
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fileHeaderLen = 30 // + filename + extra
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directoryHeaderLen = 46 // + filename + extra + comment
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directoryEndLen = 22 // + comment
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dataDescriptorLen = 12
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)
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