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-rw-r--r--src/archive/zip/reader.go453
1 files changed, 453 insertions, 0 deletions
diff --git a/src/archive/zip/reader.go b/src/archive/zip/reader.go
new file mode 100644
index 000000000..8136b840d
--- /dev/null
+++ b/src/archive/zip/reader.go
@@ -0,0 +1,453 @@
+// Copyright 2010 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"
+ "os"
+)
+
+var (
+ ErrFormat = errors.New("zip: not a valid zip file")
+ ErrAlgorithm = errors.New("zip: unsupported compression algorithm")
+ ErrChecksum = errors.New("zip: checksum error")
+)
+
+type Reader struct {
+ r io.ReaderAt
+ File []*File
+ Comment string
+}
+
+type ReadCloser struct {
+ f *os.File
+ Reader
+}
+
+type File struct {
+ FileHeader
+ zipr io.ReaderAt
+ zipsize int64
+ headerOffset int64
+}
+
+func (f *File) hasDataDescriptor() bool {
+ return f.Flags&0x8 != 0
+}
+
+// OpenReader will open the Zip file specified by name and return a ReadCloser.
+func OpenReader(name string) (*ReadCloser, error) {
+ f, err := os.Open(name)
+ if err != nil {
+ return nil, err
+ }
+ fi, err := f.Stat()
+ if err != nil {
+ f.Close()
+ return nil, err
+ }
+ r := new(ReadCloser)
+ if err := r.init(f, fi.Size()); err != nil {
+ f.Close()
+ return nil, err
+ }
+ r.f = f
+ return r, nil
+}
+
+// NewReader returns a new Reader reading from r, which is assumed to
+// have the given size in bytes.
+func NewReader(r io.ReaderAt, size int64) (*Reader, error) {
+ zr := new(Reader)
+ if err := zr.init(r, size); err != nil {
+ return nil, err
+ }
+ return zr, nil
+}
+
+func (z *Reader) init(r io.ReaderAt, size int64) error {
+ end, err := readDirectoryEnd(r, size)
+ if err != nil {
+ return err
+ }
+ z.r = r
+ z.File = make([]*File, 0, end.directoryRecords)
+ z.Comment = end.comment
+ rs := io.NewSectionReader(r, 0, size)
+ if _, err = rs.Seek(int64(end.directoryOffset), os.SEEK_SET); err != nil {
+ return err
+ }
+ buf := bufio.NewReader(rs)
+
+ // The count of files inside a zip is truncated to fit in a uint16.
+ // Gloss over this by reading headers until we encounter
+ // a bad one, and then only report a ErrFormat or UnexpectedEOF if
+ // the file count modulo 65536 is incorrect.
+ for {
+ f := &File{zipr: r, zipsize: size}
+ err = readDirectoryHeader(f, buf)
+ if err == ErrFormat || err == io.ErrUnexpectedEOF {
+ break
+ }
+ if err != nil {
+ return err
+ }
+ z.File = append(z.File, f)
+ }
+ if uint16(len(z.File)) != uint16(end.directoryRecords) { // only compare 16 bits here
+ // Return the readDirectoryHeader error if we read
+ // the wrong number of directory entries.
+ return err
+ }
+ return nil
+}
+
+// Close closes the Zip file, rendering it unusable for I/O.
+func (rc *ReadCloser) Close() error {
+ return rc.f.Close()
+}
+
+// DataOffset returns the offset of the file's possibly-compressed
+// data, relative to the beginning of the zip file.
+//
+// Most callers should instead use Open, which transparently
+// decompresses data and verifies checksums.
+func (f *File) DataOffset() (offset int64, err error) {
+ bodyOffset, err := f.findBodyOffset()
+ if err != nil {
+ return
+ }
+ return f.headerOffset + bodyOffset, nil
+}
+
+// Open returns a ReadCloser that provides access to the File's contents.
+// Multiple files may be read concurrently.
+func (f *File) Open() (rc io.ReadCloser, err error) {
+ bodyOffset, err := f.findBodyOffset()
+ if err != nil {
+ return
+ }
+ size := int64(f.CompressedSize64)
+ r := io.NewSectionReader(f.zipr, f.headerOffset+bodyOffset, size)
+ dcomp := decompressor(f.Method)
+ if dcomp == nil {
+ err = ErrAlgorithm
+ return
+ }
+ rc = dcomp(r)
+ var desr io.Reader
+ if f.hasDataDescriptor() {
+ desr = io.NewSectionReader(f.zipr, f.headerOffset+bodyOffset+size, dataDescriptorLen)
+ }
+ rc = &checksumReader{rc, crc32.NewIEEE(), f, desr, nil}
+ return
+}
+
+type checksumReader struct {
+ rc io.ReadCloser
+ hash hash.Hash32
+ f *File
+ desr io.Reader // if non-nil, where to read the data descriptor
+ err error // sticky error
+}
+
+func (r *checksumReader) Read(b []byte) (n int, err error) {
+ if r.err != nil {
+ return 0, r.err
+ }
+ n, err = r.rc.Read(b)
+ r.hash.Write(b[:n])
+ if err == nil {
+ return
+ }
+ if err == io.EOF {
+ if r.desr != nil {
+ if err1 := readDataDescriptor(r.desr, r.f); err1 != nil {
+ err = err1
+ } else if r.hash.Sum32() != r.f.CRC32 {
+ err = ErrChecksum
+ }
+ } else {
+ // If there's not a data descriptor, we still compare
+ // the CRC32 of what we've read against the file header
+ // or TOC's CRC32, if it seems like it was set.
+ if r.f.CRC32 != 0 && r.hash.Sum32() != r.f.CRC32 {
+ err = ErrChecksum
+ }
+ }
+ }
+ r.err = err
+ return
+}
+
+func (r *checksumReader) Close() error { return r.rc.Close() }
+
+// findBodyOffset does the minimum work to verify the file has a header
+// and returns the file body offset.
+func (f *File) findBodyOffset() (int64, error) {
+ var buf [fileHeaderLen]byte
+ if _, err := f.zipr.ReadAt(buf[:], f.headerOffset); err != nil {
+ return 0, err
+ }
+ b := readBuf(buf[:])
+ if sig := b.uint32(); sig != fileHeaderSignature {
+ return 0, ErrFormat
+ }
+ b = b[22:] // skip over most of the header
+ filenameLen := int(b.uint16())
+ extraLen := int(b.uint16())
+ return int64(fileHeaderLen + filenameLen + extraLen), nil
+}
+
+// readDirectoryHeader attempts to read a directory header from r.
+// It returns io.ErrUnexpectedEOF if it cannot read a complete header,
+// and ErrFormat if it doesn't find a valid header signature.
+func readDirectoryHeader(f *File, r io.Reader) error {
+ var buf [directoryHeaderLen]byte
+ if _, err := io.ReadFull(r, buf[:]); err != nil {
+ return err
+ }
+ b := readBuf(buf[:])
+ if sig := b.uint32(); sig != directoryHeaderSignature {
+ return ErrFormat
+ }
+ f.CreatorVersion = b.uint16()
+ f.ReaderVersion = b.uint16()
+ f.Flags = b.uint16()
+ f.Method = b.uint16()
+ f.ModifiedTime = b.uint16()
+ f.ModifiedDate = b.uint16()
+ f.CRC32 = b.uint32()
+ f.CompressedSize = b.uint32()
+ f.UncompressedSize = b.uint32()
+ f.CompressedSize64 = uint64(f.CompressedSize)
+ f.UncompressedSize64 = uint64(f.UncompressedSize)
+ filenameLen := int(b.uint16())
+ extraLen := int(b.uint16())
+ commentLen := int(b.uint16())
+ b = b[4:] // skipped start disk number and internal attributes (2x uint16)
+ f.ExternalAttrs = b.uint32()
+ f.headerOffset = int64(b.uint32())
+ d := make([]byte, filenameLen+extraLen+commentLen)
+ if _, err := io.ReadFull(r, d); err != nil {
+ return err
+ }
+ f.Name = string(d[:filenameLen])
+ f.Extra = d[filenameLen : filenameLen+extraLen]
+ f.Comment = string(d[filenameLen+extraLen:])
+
+ if len(f.Extra) > 0 {
+ b := readBuf(f.Extra)
+ for len(b) >= 4 { // need at least tag and size
+ tag := b.uint16()
+ size := b.uint16()
+ if int(size) > len(b) {
+ return ErrFormat
+ }
+ if tag == zip64ExtraId {
+ // update directory values from the zip64 extra block
+ eb := readBuf(b[:size])
+ if len(eb) >= 8 {
+ f.UncompressedSize64 = eb.uint64()
+ }
+ if len(eb) >= 8 {
+ f.CompressedSize64 = eb.uint64()
+ }
+ if len(eb) >= 8 {
+ f.headerOffset = int64(eb.uint64())
+ }
+ }
+ b = b[size:]
+ }
+ // Should have consumed the whole header.
+ // But popular zip & JAR creation tools are broken and
+ // may pad extra zeros at the end, so accept those
+ // too. See golang.org/issue/8186.
+ for _, v := range b {
+ if v != 0 {
+ return ErrFormat
+ }
+ }
+ }
+ return nil
+}
+
+func readDataDescriptor(r io.Reader, f *File) error {
+ var buf [dataDescriptorLen]byte
+
+ // The spec says: "Although not originally assigned a
+ // signature, the value 0x08074b50 has commonly been adopted
+ // as a signature value for the data descriptor record.
+ // Implementers should be aware that ZIP files may be
+ // encountered with or without this signature marking data
+ // descriptors and should account for either case when reading
+ // ZIP files to ensure compatibility."
+ //
+ // dataDescriptorLen includes the size of the signature but
+ // first read just those 4 bytes to see if it exists.
+ if _, err := io.ReadFull(r, buf[:4]); err != nil {
+ return err
+ }
+ off := 0
+ maybeSig := readBuf(buf[:4])
+ if maybeSig.uint32() != dataDescriptorSignature {
+ // No data descriptor signature. Keep these four
+ // bytes.
+ off += 4
+ }
+ if _, err := io.ReadFull(r, buf[off:12]); err != nil {
+ return err
+ }
+ b := readBuf(buf[:12])
+ if b.uint32() != f.CRC32 {
+ return ErrChecksum
+ }
+
+ // The two sizes that follow here can be either 32 bits or 64 bits
+ // but the spec is not very clear on this and different
+ // interpretations has been made causing incompatibilities. We
+ // already have the sizes from the central directory so we can
+ // just ignore these.
+
+ return nil
+}
+
+func readDirectoryEnd(r io.ReaderAt, size int64) (dir *directoryEnd, err error) {
+ // look for directoryEndSignature in the last 1k, then in the last 65k
+ var buf []byte
+ var directoryEndOffset int64
+ for i, bLen := range []int64{1024, 65 * 1024} {
+ if bLen > size {
+ bLen = size
+ }
+ buf = make([]byte, int(bLen))
+ if _, err := r.ReadAt(buf, size-bLen); err != nil && err != io.EOF {
+ return nil, err
+ }
+ if p := findSignatureInBlock(buf); p >= 0 {
+ buf = buf[p:]
+ directoryEndOffset = size - bLen + int64(p)
+ break
+ }
+ if i == 1 || bLen == size {
+ return nil, ErrFormat
+ }
+ }
+
+ // read header into struct
+ b := readBuf(buf[4:]) // skip signature
+ d := &directoryEnd{
+ diskNbr: uint32(b.uint16()),
+ dirDiskNbr: uint32(b.uint16()),
+ dirRecordsThisDisk: uint64(b.uint16()),
+ directoryRecords: uint64(b.uint16()),
+ directorySize: uint64(b.uint32()),
+ directoryOffset: uint64(b.uint32()),
+ commentLen: b.uint16(),
+ }
+ l := int(d.commentLen)
+ if l > len(b) {
+ return nil, errors.New("zip: invalid comment length")
+ }
+ d.comment = string(b[:l])
+
+ p, err := findDirectory64End(r, directoryEndOffset)
+ if err == nil && p >= 0 {
+ err = readDirectory64End(r, p, d)
+ }
+ if err != nil {
+ return nil, err
+ }
+
+ // Make sure directoryOffset points to somewhere in our file.
+ if o := int64(d.directoryOffset); o < 0 || o >= size {
+ return nil, ErrFormat
+ }
+ return d, nil
+}
+
+// findDirectory64End tries to read the zip64 locator just before the
+// directory end and returns the offset of the zip64 directory end if
+// found.
+func findDirectory64End(r io.ReaderAt, directoryEndOffset int64) (int64, error) {
+ locOffset := directoryEndOffset - directory64LocLen
+ if locOffset < 0 {
+ return -1, nil // no need to look for a header outside the file
+ }
+ buf := make([]byte, directory64LocLen)
+ if _, err := r.ReadAt(buf, locOffset); err != nil {
+ return -1, err
+ }
+ b := readBuf(buf)
+ if sig := b.uint32(); sig != directory64LocSignature {
+ return -1, nil
+ }
+ b = b[4:] // skip number of the disk with the start of the zip64 end of central directory
+ p := b.uint64() // relative offset of the zip64 end of central directory record
+ return int64(p), nil
+}
+
+// readDirectory64End reads the zip64 directory end and updates the
+// directory end with the zip64 directory end values.
+func readDirectory64End(r io.ReaderAt, offset int64, d *directoryEnd) (err error) {
+ buf := make([]byte, directory64EndLen)
+ if _, err := r.ReadAt(buf, offset); err != nil {
+ return err
+ }
+
+ b := readBuf(buf)
+ if sig := b.uint32(); sig != directory64EndSignature {
+ return ErrFormat
+ }
+
+ b = b[12:] // skip dir size, version and version needed (uint64 + 2x uint16)
+ d.diskNbr = b.uint32() // number of this disk
+ d.dirDiskNbr = b.uint32() // number of the disk with the start of the central directory
+ d.dirRecordsThisDisk = b.uint64() // total number of entries in the central directory on this disk
+ d.directoryRecords = b.uint64() // total number of entries in the central directory
+ d.directorySize = b.uint64() // size of the central directory
+ d.directoryOffset = b.uint64() // offset of start of central directory with respect to the starting disk number
+
+ return nil
+}
+
+func findSignatureInBlock(b []byte) int {
+ for i := len(b) - directoryEndLen; i >= 0; i-- {
+ // defined from directoryEndSignature in struct.go
+ if b[i] == 'P' && b[i+1] == 'K' && b[i+2] == 0x05 && b[i+3] == 0x06 {
+ // n is length of comment
+ n := int(b[i+directoryEndLen-2]) | int(b[i+directoryEndLen-1])<<8
+ if n+directoryEndLen+i <= len(b) {
+ return i
+ }
+ }
+ }
+ return -1
+}
+
+type readBuf []byte
+
+func (b *readBuf) uint16() uint16 {
+ v := binary.LittleEndian.Uint16(*b)
+ *b = (*b)[2:]
+ return v
+}
+
+func (b *readBuf) uint32() uint32 {
+ v := binary.LittleEndian.Uint32(*b)
+ *b = (*b)[4:]
+ return v
+}
+
+func (b *readBuf) uint64() uint64 {
+ v := binary.LittleEndian.Uint64(*b)
+ *b = (*b)[8:]
+ return v
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-17 10:18:19 +0000