mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
synced 2024-12-25 03:40:10 +01:00
2084921e64
`github.com/klauspost/compress/gzip` is more optimized than `compress/gzip`. This gives better gzip compression and decompression speeds.
345 lines
9.5 KiB
Go
345 lines
9.5 KiB
Go
// Copyright 2009 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 gzip implements reading and writing of gzip format compressed files,
|
|
// as specified in RFC 1952.
|
|
package gzip
|
|
|
|
import (
|
|
"bufio"
|
|
"encoding/binary"
|
|
"errors"
|
|
"hash/crc32"
|
|
"io"
|
|
"time"
|
|
|
|
"github.com/klauspost/compress/flate"
|
|
)
|
|
|
|
const (
|
|
gzipID1 = 0x1f
|
|
gzipID2 = 0x8b
|
|
gzipDeflate = 8
|
|
flagText = 1 << 0
|
|
flagHdrCrc = 1 << 1
|
|
flagExtra = 1 << 2
|
|
flagName = 1 << 3
|
|
flagComment = 1 << 4
|
|
)
|
|
|
|
var (
|
|
// ErrChecksum is returned when reading GZIP data that has an invalid checksum.
|
|
ErrChecksum = errors.New("gzip: invalid checksum")
|
|
// ErrHeader is returned when reading GZIP data that has an invalid header.
|
|
ErrHeader = errors.New("gzip: invalid header")
|
|
)
|
|
|
|
var le = binary.LittleEndian
|
|
|
|
// noEOF converts io.EOF to io.ErrUnexpectedEOF.
|
|
func noEOF(err error) error {
|
|
if err == io.EOF {
|
|
return io.ErrUnexpectedEOF
|
|
}
|
|
return err
|
|
}
|
|
|
|
// The gzip file stores a header giving metadata about the compressed file.
|
|
// That header is exposed as the fields of the Writer and Reader structs.
|
|
//
|
|
// Strings must be UTF-8 encoded and may only contain Unicode code points
|
|
// U+0001 through U+00FF, due to limitations of the GZIP file format.
|
|
type Header struct {
|
|
Comment string // comment
|
|
Extra []byte // "extra data"
|
|
ModTime time.Time // modification time
|
|
Name string // file name
|
|
OS byte // operating system type
|
|
}
|
|
|
|
// A Reader is an io.Reader that can be read to retrieve
|
|
// uncompressed data from a gzip-format compressed file.
|
|
//
|
|
// In general, a gzip file can be a concatenation of gzip files,
|
|
// each with its own header. Reads from the Reader
|
|
// return the concatenation of the uncompressed data of each.
|
|
// Only the first header is recorded in the Reader fields.
|
|
//
|
|
// Gzip files store a length and checksum of the uncompressed data.
|
|
// The Reader will return a ErrChecksum when Read
|
|
// reaches the end of the uncompressed data if it does not
|
|
// have the expected length or checksum. Clients should treat data
|
|
// returned by Read as tentative until they receive the io.EOF
|
|
// marking the end of the data.
|
|
type Reader struct {
|
|
Header // valid after NewReader or Reader.Reset
|
|
r flate.Reader
|
|
decompressor io.ReadCloser
|
|
digest uint32 // CRC-32, IEEE polynomial (section 8)
|
|
size uint32 // Uncompressed size (section 2.3.1)
|
|
buf [512]byte
|
|
err error
|
|
multistream bool
|
|
}
|
|
|
|
// NewReader creates a new Reader reading the given reader.
|
|
// If r does not also implement io.ByteReader,
|
|
// the decompressor may read more data than necessary from r.
|
|
//
|
|
// It is the caller's responsibility to call Close on the Reader when done.
|
|
//
|
|
// The Reader.Header fields will be valid in the Reader returned.
|
|
func NewReader(r io.Reader) (*Reader, error) {
|
|
z := new(Reader)
|
|
if err := z.Reset(r); err != nil {
|
|
return nil, err
|
|
}
|
|
return z, nil
|
|
}
|
|
|
|
// Reset discards the Reader z's state and makes it equivalent to the
|
|
// result of its original state from NewReader, but reading from r instead.
|
|
// This permits reusing a Reader rather than allocating a new one.
|
|
func (z *Reader) Reset(r io.Reader) error {
|
|
*z = Reader{
|
|
decompressor: z.decompressor,
|
|
multistream: true,
|
|
}
|
|
if rr, ok := r.(flate.Reader); ok {
|
|
z.r = rr
|
|
} else {
|
|
z.r = bufio.NewReader(r)
|
|
}
|
|
z.Header, z.err = z.readHeader()
|
|
return z.err
|
|
}
|
|
|
|
// Multistream controls whether the reader supports multistream files.
|
|
//
|
|
// If enabled (the default), the Reader expects the input to be a sequence
|
|
// of individually gzipped data streams, each with its own header and
|
|
// trailer, ending at EOF. The effect is that the concatenation of a sequence
|
|
// of gzipped files is treated as equivalent to the gzip of the concatenation
|
|
// of the sequence. This is standard behavior for gzip readers.
|
|
//
|
|
// Calling Multistream(false) disables this behavior; disabling the behavior
|
|
// can be useful when reading file formats that distinguish individual gzip
|
|
// data streams or mix gzip data streams with other data streams.
|
|
// In this mode, when the Reader reaches the end of the data stream,
|
|
// Read returns io.EOF. If the underlying reader implements io.ByteReader,
|
|
// it will be left positioned just after the gzip stream.
|
|
// To start the next stream, call z.Reset(r) followed by z.Multistream(false).
|
|
// If there is no next stream, z.Reset(r) will return io.EOF.
|
|
func (z *Reader) Multistream(ok bool) {
|
|
z.multistream = ok
|
|
}
|
|
|
|
// readString reads a NUL-terminated string from z.r.
|
|
// It treats the bytes read as being encoded as ISO 8859-1 (Latin-1) and
|
|
// will output a string encoded using UTF-8.
|
|
// This method always updates z.digest with the data read.
|
|
func (z *Reader) readString() (string, error) {
|
|
var err error
|
|
needConv := false
|
|
for i := 0; ; i++ {
|
|
if i >= len(z.buf) {
|
|
return "", ErrHeader
|
|
}
|
|
z.buf[i], err = z.r.ReadByte()
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
if z.buf[i] > 0x7f {
|
|
needConv = true
|
|
}
|
|
if z.buf[i] == 0 {
|
|
// Digest covers the NUL terminator.
|
|
z.digest = crc32.Update(z.digest, crc32.IEEETable, z.buf[:i+1])
|
|
|
|
// Strings are ISO 8859-1, Latin-1 (RFC 1952, section 2.3.1).
|
|
if needConv {
|
|
s := make([]rune, 0, i)
|
|
for _, v := range z.buf[:i] {
|
|
s = append(s, rune(v))
|
|
}
|
|
return string(s), nil
|
|
}
|
|
return string(z.buf[:i]), nil
|
|
}
|
|
}
|
|
}
|
|
|
|
// readHeader reads the GZIP header according to section 2.3.1.
|
|
// This method does not set z.err.
|
|
func (z *Reader) readHeader() (hdr Header, err error) {
|
|
if _, err = io.ReadFull(z.r, z.buf[:10]); err != nil {
|
|
// RFC 1952, section 2.2, says the following:
|
|
// A gzip file consists of a series of "members" (compressed data sets).
|
|
//
|
|
// Other than this, the specification does not clarify whether a
|
|
// "series" is defined as "one or more" or "zero or more". To err on the
|
|
// side of caution, Go interprets this to mean "zero or more".
|
|
// Thus, it is okay to return io.EOF here.
|
|
return hdr, err
|
|
}
|
|
if z.buf[0] != gzipID1 || z.buf[1] != gzipID2 || z.buf[2] != gzipDeflate {
|
|
return hdr, ErrHeader
|
|
}
|
|
flg := z.buf[3]
|
|
hdr.ModTime = time.Unix(int64(le.Uint32(z.buf[4:8])), 0)
|
|
// z.buf[8] is XFL and is currently ignored.
|
|
hdr.OS = z.buf[9]
|
|
z.digest = crc32.ChecksumIEEE(z.buf[:10])
|
|
|
|
if flg&flagExtra != 0 {
|
|
if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil {
|
|
return hdr, noEOF(err)
|
|
}
|
|
z.digest = crc32.Update(z.digest, crc32.IEEETable, z.buf[:2])
|
|
data := make([]byte, le.Uint16(z.buf[:2]))
|
|
if _, err = io.ReadFull(z.r, data); err != nil {
|
|
return hdr, noEOF(err)
|
|
}
|
|
z.digest = crc32.Update(z.digest, crc32.IEEETable, data)
|
|
hdr.Extra = data
|
|
}
|
|
|
|
var s string
|
|
if flg&flagName != 0 {
|
|
if s, err = z.readString(); err != nil {
|
|
return hdr, err
|
|
}
|
|
hdr.Name = s
|
|
}
|
|
|
|
if flg&flagComment != 0 {
|
|
if s, err = z.readString(); err != nil {
|
|
return hdr, err
|
|
}
|
|
hdr.Comment = s
|
|
}
|
|
|
|
if flg&flagHdrCrc != 0 {
|
|
if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil {
|
|
return hdr, noEOF(err)
|
|
}
|
|
digest := le.Uint16(z.buf[:2])
|
|
if digest != uint16(z.digest) {
|
|
return hdr, ErrHeader
|
|
}
|
|
}
|
|
|
|
z.digest = 0
|
|
if z.decompressor == nil {
|
|
z.decompressor = flate.NewReader(z.r)
|
|
} else {
|
|
z.decompressor.(flate.Resetter).Reset(z.r, nil)
|
|
}
|
|
return hdr, nil
|
|
}
|
|
|
|
// Read implements io.Reader, reading uncompressed bytes from its underlying Reader.
|
|
func (z *Reader) Read(p []byte) (n int, err error) {
|
|
if z.err != nil {
|
|
return 0, z.err
|
|
}
|
|
|
|
n, z.err = z.decompressor.Read(p)
|
|
z.digest = crc32.Update(z.digest, crc32.IEEETable, p[:n])
|
|
z.size += uint32(n)
|
|
if z.err != io.EOF {
|
|
// In the normal case we return here.
|
|
return n, z.err
|
|
}
|
|
|
|
// Finished file; check checksum and size.
|
|
if _, err := io.ReadFull(z.r, z.buf[:8]); err != nil {
|
|
z.err = noEOF(err)
|
|
return n, z.err
|
|
}
|
|
digest := le.Uint32(z.buf[:4])
|
|
size := le.Uint32(z.buf[4:8])
|
|
if digest != z.digest || size != z.size {
|
|
z.err = ErrChecksum
|
|
return n, z.err
|
|
}
|
|
z.digest, z.size = 0, 0
|
|
|
|
// File is ok; check if there is another.
|
|
if !z.multistream {
|
|
return n, io.EOF
|
|
}
|
|
z.err = nil // Remove io.EOF
|
|
|
|
if _, z.err = z.readHeader(); z.err != nil {
|
|
return n, z.err
|
|
}
|
|
|
|
// Read from next file, if necessary.
|
|
if n > 0 {
|
|
return n, nil
|
|
}
|
|
return z.Read(p)
|
|
}
|
|
|
|
// Support the io.WriteTo interface for io.Copy and friends.
|
|
func (z *Reader) WriteTo(w io.Writer) (int64, error) {
|
|
total := int64(0)
|
|
crcWriter := crc32.NewIEEE()
|
|
for {
|
|
if z.err != nil {
|
|
if z.err == io.EOF {
|
|
return total, nil
|
|
}
|
|
return total, z.err
|
|
}
|
|
|
|
// We write both to output and digest.
|
|
mw := io.MultiWriter(w, crcWriter)
|
|
n, err := z.decompressor.(io.WriterTo).WriteTo(mw)
|
|
total += n
|
|
z.size += uint32(n)
|
|
if err != nil {
|
|
z.err = err
|
|
return total, z.err
|
|
}
|
|
|
|
// Finished file; check checksum + size.
|
|
if _, err := io.ReadFull(z.r, z.buf[0:8]); err != nil {
|
|
if err == io.EOF {
|
|
err = io.ErrUnexpectedEOF
|
|
}
|
|
z.err = err
|
|
return total, err
|
|
}
|
|
z.digest = crcWriter.Sum32()
|
|
digest := le.Uint32(z.buf[:4])
|
|
size := le.Uint32(z.buf[4:8])
|
|
if digest != z.digest || size != z.size {
|
|
z.err = ErrChecksum
|
|
return total, z.err
|
|
}
|
|
z.digest, z.size = 0, 0
|
|
|
|
// File is ok; check if there is another.
|
|
if !z.multistream {
|
|
return total, nil
|
|
}
|
|
crcWriter.Reset()
|
|
z.err = nil // Remove io.EOF
|
|
|
|
if _, z.err = z.readHeader(); z.err != nil {
|
|
if z.err == io.EOF {
|
|
return total, nil
|
|
}
|
|
return total, z.err
|
|
}
|
|
}
|
|
}
|
|
|
|
// Close closes the Reader. It does not close the underlying io.Reader.
|
|
// In order for the GZIP checksum to be verified, the reader must be
|
|
// fully consumed until the io.EOF.
|
|
func (z *Reader) Close() error { return z.decompressor.Close() }
|