mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-05 10:02:47 +00:00
435 lines
13 KiB
Go
435 lines
13 KiB
Go
|
// Copyright 2019+ Klaus Post. All rights reserved.
|
||
|
// License information can be found in the LICENSE file.
|
||
|
// Based on work by Yann Collet, released under BSD License.
|
||
|
|
||
|
package zstd
|
||
|
|
||
|
import (
|
||
|
"encoding/binary"
|
||
|
"errors"
|
||
|
"hash/crc32"
|
||
|
"io"
|
||
|
|
||
|
"github.com/klauspost/compress/huff0"
|
||
|
snappy "github.com/klauspost/compress/internal/snapref"
|
||
|
)
|
||
|
|
||
|
const (
|
||
|
snappyTagLiteral = 0x00
|
||
|
snappyTagCopy1 = 0x01
|
||
|
snappyTagCopy2 = 0x02
|
||
|
snappyTagCopy4 = 0x03
|
||
|
)
|
||
|
|
||
|
const (
|
||
|
snappyChecksumSize = 4
|
||
|
snappyMagicBody = "sNaPpY"
|
||
|
|
||
|
// snappyMaxBlockSize is the maximum size of the input to encodeBlock. It is not
|
||
|
// part of the wire format per se, but some parts of the encoder assume
|
||
|
// that an offset fits into a uint16.
|
||
|
//
|
||
|
// Also, for the framing format (Writer type instead of Encode function),
|
||
|
// https://github.com/google/snappy/blob/master/framing_format.txt says
|
||
|
// that "the uncompressed data in a chunk must be no longer than 65536
|
||
|
// bytes".
|
||
|
snappyMaxBlockSize = 65536
|
||
|
|
||
|
// snappyMaxEncodedLenOfMaxBlockSize equals MaxEncodedLen(snappyMaxBlockSize), but is
|
||
|
// hard coded to be a const instead of a variable, so that obufLen can also
|
||
|
// be a const. Their equivalence is confirmed by
|
||
|
// TestMaxEncodedLenOfMaxBlockSize.
|
||
|
snappyMaxEncodedLenOfMaxBlockSize = 76490
|
||
|
)
|
||
|
|
||
|
const (
|
||
|
chunkTypeCompressedData = 0x00
|
||
|
chunkTypeUncompressedData = 0x01
|
||
|
chunkTypePadding = 0xfe
|
||
|
chunkTypeStreamIdentifier = 0xff
|
||
|
)
|
||
|
|
||
|
var (
|
||
|
// ErrSnappyCorrupt reports that the input is invalid.
|
||
|
ErrSnappyCorrupt = errors.New("snappy: corrupt input")
|
||
|
// ErrSnappyTooLarge reports that the uncompressed length is too large.
|
||
|
ErrSnappyTooLarge = errors.New("snappy: decoded block is too large")
|
||
|
// ErrSnappyUnsupported reports that the input isn't supported.
|
||
|
ErrSnappyUnsupported = errors.New("snappy: unsupported input")
|
||
|
|
||
|
errUnsupportedLiteralLength = errors.New("snappy: unsupported literal length")
|
||
|
)
|
||
|
|
||
|
// SnappyConverter can read SnappyConverter-compressed streams and convert them to zstd.
|
||
|
// Conversion is done by converting the stream directly from Snappy without intermediate
|
||
|
// full decoding.
|
||
|
// Therefore the compression ratio is much less than what can be done by a full decompression
|
||
|
// and compression, and a faulty Snappy stream may lead to a faulty Zstandard stream without
|
||
|
// any errors being generated.
|
||
|
// No CRC value is being generated and not all CRC values of the Snappy stream are checked.
|
||
|
// However, it provides really fast recompression of Snappy streams.
|
||
|
// The converter can be reused to avoid allocations, even after errors.
|
||
|
type SnappyConverter struct {
|
||
|
r io.Reader
|
||
|
err error
|
||
|
buf []byte
|
||
|
block *blockEnc
|
||
|
}
|
||
|
|
||
|
// Convert the Snappy stream supplied in 'in' and write the zStandard stream to 'w'.
|
||
|
// If any error is detected on the Snappy stream it is returned.
|
||
|
// The number of bytes written is returned.
|
||
|
func (r *SnappyConverter) Convert(in io.Reader, w io.Writer) (int64, error) {
|
||
|
initPredefined()
|
||
|
r.err = nil
|
||
|
r.r = in
|
||
|
if r.block == nil {
|
||
|
r.block = &blockEnc{}
|
||
|
r.block.init()
|
||
|
}
|
||
|
r.block.initNewEncode()
|
||
|
if len(r.buf) != snappyMaxEncodedLenOfMaxBlockSize+snappyChecksumSize {
|
||
|
r.buf = make([]byte, snappyMaxEncodedLenOfMaxBlockSize+snappyChecksumSize)
|
||
|
}
|
||
|
r.block.litEnc.Reuse = huff0.ReusePolicyNone
|
||
|
var written int64
|
||
|
var readHeader bool
|
||
|
{
|
||
|
header := frameHeader{WindowSize: snappyMaxBlockSize}.appendTo(r.buf[:0])
|
||
|
|
||
|
var n int
|
||
|
n, r.err = w.Write(header)
|
||
|
if r.err != nil {
|
||
|
return written, r.err
|
||
|
}
|
||
|
written += int64(n)
|
||
|
}
|
||
|
|
||
|
for {
|
||
|
if !r.readFull(r.buf[:4], true) {
|
||
|
// Add empty last block
|
||
|
r.block.reset(nil)
|
||
|
r.block.last = true
|
||
|
err := r.block.encodeLits(r.block.literals, false)
|
||
|
if err != nil {
|
||
|
return written, err
|
||
|
}
|
||
|
n, err := w.Write(r.block.output)
|
||
|
if err != nil {
|
||
|
return written, err
|
||
|
}
|
||
|
written += int64(n)
|
||
|
|
||
|
return written, r.err
|
||
|
}
|
||
|
chunkType := r.buf[0]
|
||
|
if !readHeader {
|
||
|
if chunkType != chunkTypeStreamIdentifier {
|
||
|
println("chunkType != chunkTypeStreamIdentifier", chunkType)
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
return written, r.err
|
||
|
}
|
||
|
readHeader = true
|
||
|
}
|
||
|
chunkLen := int(r.buf[1]) | int(r.buf[2])<<8 | int(r.buf[3])<<16
|
||
|
if chunkLen > len(r.buf) {
|
||
|
println("chunkLen > len(r.buf)", chunkType)
|
||
|
r.err = ErrSnappyUnsupported
|
||
|
return written, r.err
|
||
|
}
|
||
|
|
||
|
// The chunk types are specified at
|
||
|
// https://github.com/google/snappy/blob/master/framing_format.txt
|
||
|
switch chunkType {
|
||
|
case chunkTypeCompressedData:
|
||
|
// Section 4.2. Compressed data (chunk type 0x00).
|
||
|
if chunkLen < snappyChecksumSize {
|
||
|
println("chunkLen < snappyChecksumSize", chunkLen, snappyChecksumSize)
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
return written, r.err
|
||
|
}
|
||
|
buf := r.buf[:chunkLen]
|
||
|
if !r.readFull(buf, false) {
|
||
|
return written, r.err
|
||
|
}
|
||
|
//checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
|
||
|
buf = buf[snappyChecksumSize:]
|
||
|
|
||
|
n, hdr, err := snappyDecodedLen(buf)
|
||
|
if err != nil {
|
||
|
r.err = err
|
||
|
return written, r.err
|
||
|
}
|
||
|
buf = buf[hdr:]
|
||
|
if n > snappyMaxBlockSize {
|
||
|
println("n > snappyMaxBlockSize", n, snappyMaxBlockSize)
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
return written, r.err
|
||
|
}
|
||
|
r.block.reset(nil)
|
||
|
r.block.pushOffsets()
|
||
|
if err := decodeSnappy(r.block, buf); err != nil {
|
||
|
r.err = err
|
||
|
return written, r.err
|
||
|
}
|
||
|
if r.block.size+r.block.extraLits != n {
|
||
|
printf("invalid size, want %d, got %d\n", n, r.block.size+r.block.extraLits)
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
return written, r.err
|
||
|
}
|
||
|
err = r.block.encode(nil, false, false)
|
||
|
switch err {
|
||
|
case errIncompressible:
|
||
|
r.block.popOffsets()
|
||
|
r.block.reset(nil)
|
||
|
r.block.literals, err = snappy.Decode(r.block.literals[:n], r.buf[snappyChecksumSize:chunkLen])
|
||
|
if err != nil {
|
||
|
return written, err
|
||
|
}
|
||
|
err = r.block.encodeLits(r.block.literals, false)
|
||
|
if err != nil {
|
||
|
return written, err
|
||
|
}
|
||
|
case nil:
|
||
|
default:
|
||
|
return written, err
|
||
|
}
|
||
|
|
||
|
n, r.err = w.Write(r.block.output)
|
||
|
if r.err != nil {
|
||
|
return written, err
|
||
|
}
|
||
|
written += int64(n)
|
||
|
continue
|
||
|
case chunkTypeUncompressedData:
|
||
|
if debugEncoder {
|
||
|
println("Uncompressed, chunklen", chunkLen)
|
||
|
}
|
||
|
// Section 4.3. Uncompressed data (chunk type 0x01).
|
||
|
if chunkLen < snappyChecksumSize {
|
||
|
println("chunkLen < snappyChecksumSize", chunkLen, snappyChecksumSize)
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
return written, r.err
|
||
|
}
|
||
|
r.block.reset(nil)
|
||
|
buf := r.buf[:snappyChecksumSize]
|
||
|
if !r.readFull(buf, false) {
|
||
|
return written, r.err
|
||
|
}
|
||
|
checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
|
||
|
// Read directly into r.decoded instead of via r.buf.
|
||
|
n := chunkLen - snappyChecksumSize
|
||
|
if n > snappyMaxBlockSize {
|
||
|
println("n > snappyMaxBlockSize", n, snappyMaxBlockSize)
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
return written, r.err
|
||
|
}
|
||
|
r.block.literals = r.block.literals[:n]
|
||
|
if !r.readFull(r.block.literals, false) {
|
||
|
return written, r.err
|
||
|
}
|
||
|
if snappyCRC(r.block.literals) != checksum {
|
||
|
println("literals crc mismatch")
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
return written, r.err
|
||
|
}
|
||
|
err := r.block.encodeLits(r.block.literals, false)
|
||
|
if err != nil {
|
||
|
return written, err
|
||
|
}
|
||
|
n, r.err = w.Write(r.block.output)
|
||
|
if r.err != nil {
|
||
|
return written, err
|
||
|
}
|
||
|
written += int64(n)
|
||
|
continue
|
||
|
|
||
|
case chunkTypeStreamIdentifier:
|
||
|
if debugEncoder {
|
||
|
println("stream id", chunkLen, len(snappyMagicBody))
|
||
|
}
|
||
|
// Section 4.1. Stream identifier (chunk type 0xff).
|
||
|
if chunkLen != len(snappyMagicBody) {
|
||
|
println("chunkLen != len(snappyMagicBody)", chunkLen, len(snappyMagicBody))
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
return written, r.err
|
||
|
}
|
||
|
if !r.readFull(r.buf[:len(snappyMagicBody)], false) {
|
||
|
return written, r.err
|
||
|
}
|
||
|
for i := 0; i < len(snappyMagicBody); i++ {
|
||
|
if r.buf[i] != snappyMagicBody[i] {
|
||
|
println("r.buf[i] != snappyMagicBody[i]", r.buf[i], snappyMagicBody[i], i)
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
return written, r.err
|
||
|
}
|
||
|
}
|
||
|
continue
|
||
|
}
|
||
|
|
||
|
if chunkType <= 0x7f {
|
||
|
// Section 4.5. Reserved unskippable chunks (chunk types 0x02-0x7f).
|
||
|
println("chunkType <= 0x7f")
|
||
|
r.err = ErrSnappyUnsupported
|
||
|
return written, r.err
|
||
|
}
|
||
|
// Section 4.4 Padding (chunk type 0xfe).
|
||
|
// Section 4.6. Reserved skippable chunks (chunk types 0x80-0xfd).
|
||
|
if !r.readFull(r.buf[:chunkLen], false) {
|
||
|
return written, r.err
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// decodeSnappy writes the decoding of src to dst. It assumes that the varint-encoded
|
||
|
// length of the decompressed bytes has already been read.
|
||
|
func decodeSnappy(blk *blockEnc, src []byte) error {
|
||
|
//decodeRef(make([]byte, snappyMaxBlockSize), src)
|
||
|
var s, length int
|
||
|
lits := blk.extraLits
|
||
|
var offset uint32
|
||
|
for s < len(src) {
|
||
|
switch src[s] & 0x03 {
|
||
|
case snappyTagLiteral:
|
||
|
x := uint32(src[s] >> 2)
|
||
|
switch {
|
||
|
case x < 60:
|
||
|
s++
|
||
|
case x == 60:
|
||
|
s += 2
|
||
|
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
|
||
|
println("uint(s) > uint(len(src)", s, src)
|
||
|
return ErrSnappyCorrupt
|
||
|
}
|
||
|
x = uint32(src[s-1])
|
||
|
case x == 61:
|
||
|
s += 3
|
||
|
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
|
||
|
println("uint(s) > uint(len(src)", s, src)
|
||
|
return ErrSnappyCorrupt
|
||
|
}
|
||
|
x = uint32(src[s-2]) | uint32(src[s-1])<<8
|
||
|
case x == 62:
|
||
|
s += 4
|
||
|
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
|
||
|
println("uint(s) > uint(len(src)", s, src)
|
||
|
return ErrSnappyCorrupt
|
||
|
}
|
||
|
x = uint32(src[s-3]) | uint32(src[s-2])<<8 | uint32(src[s-1])<<16
|
||
|
case x == 63:
|
||
|
s += 5
|
||
|
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
|
||
|
println("uint(s) > uint(len(src)", s, src)
|
||
|
return ErrSnappyCorrupt
|
||
|
}
|
||
|
x = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
|
||
|
}
|
||
|
if x > snappyMaxBlockSize {
|
||
|
println("x > snappyMaxBlockSize", x, snappyMaxBlockSize)
|
||
|
return ErrSnappyCorrupt
|
||
|
}
|
||
|
length = int(x) + 1
|
||
|
if length <= 0 {
|
||
|
println("length <= 0 ", length)
|
||
|
|
||
|
return errUnsupportedLiteralLength
|
||
|
}
|
||
|
//if length > snappyMaxBlockSize-d || uint32(length) > len(src)-s {
|
||
|
// return ErrSnappyCorrupt
|
||
|
//}
|
||
|
|
||
|
blk.literals = append(blk.literals, src[s:s+length]...)
|
||
|
//println(length, "litLen")
|
||
|
lits += length
|
||
|
s += length
|
||
|
continue
|
||
|
|
||
|
case snappyTagCopy1:
|
||
|
s += 2
|
||
|
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
|
||
|
println("uint(s) > uint(len(src)", s, len(src))
|
||
|
return ErrSnappyCorrupt
|
||
|
}
|
||
|
length = 4 + int(src[s-2])>>2&0x7
|
||
|
offset = uint32(src[s-2])&0xe0<<3 | uint32(src[s-1])
|
||
|
|
||
|
case snappyTagCopy2:
|
||
|
s += 3
|
||
|
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
|
||
|
println("uint(s) > uint(len(src)", s, len(src))
|
||
|
return ErrSnappyCorrupt
|
||
|
}
|
||
|
length = 1 + int(src[s-3])>>2
|
||
|
offset = uint32(src[s-2]) | uint32(src[s-1])<<8
|
||
|
|
||
|
case snappyTagCopy4:
|
||
|
s += 5
|
||
|
if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
|
||
|
println("uint(s) > uint(len(src)", s, len(src))
|
||
|
return ErrSnappyCorrupt
|
||
|
}
|
||
|
length = 1 + int(src[s-5])>>2
|
||
|
offset = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
|
||
|
}
|
||
|
|
||
|
if offset <= 0 || blk.size+lits < int(offset) /*|| length > len(blk)-d */ {
|
||
|
println("offset <= 0 || blk.size+lits < int(offset)", offset, blk.size+lits, int(offset), blk.size, lits)
|
||
|
|
||
|
return ErrSnappyCorrupt
|
||
|
}
|
||
|
|
||
|
// Check if offset is one of the recent offsets.
|
||
|
// Adjusts the output offset accordingly.
|
||
|
// Gives a tiny bit of compression, typically around 1%.
|
||
|
if false {
|
||
|
offset = blk.matchOffset(offset, uint32(lits))
|
||
|
} else {
|
||
|
offset += 3
|
||
|
}
|
||
|
|
||
|
blk.sequences = append(blk.sequences, seq{
|
||
|
litLen: uint32(lits),
|
||
|
offset: offset,
|
||
|
matchLen: uint32(length) - zstdMinMatch,
|
||
|
})
|
||
|
blk.size += length + lits
|
||
|
lits = 0
|
||
|
}
|
||
|
blk.extraLits = lits
|
||
|
return nil
|
||
|
}
|
||
|
|
||
|
func (r *SnappyConverter) readFull(p []byte, allowEOF bool) (ok bool) {
|
||
|
if _, r.err = io.ReadFull(r.r, p); r.err != nil {
|
||
|
if r.err == io.ErrUnexpectedEOF || (r.err == io.EOF && !allowEOF) {
|
||
|
r.err = ErrSnappyCorrupt
|
||
|
}
|
||
|
return false
|
||
|
}
|
||
|
return true
|
||
|
}
|
||
|
|
||
|
var crcTable = crc32.MakeTable(crc32.Castagnoli)
|
||
|
|
||
|
// crc implements the checksum specified in section 3 of
|
||
|
// https://github.com/google/snappy/blob/master/framing_format.txt
|
||
|
func snappyCRC(b []byte) uint32 {
|
||
|
c := crc32.Update(0, crcTable, b)
|
||
|
return c>>15 | c<<17 + 0xa282ead8
|
||
|
}
|
||
|
|
||
|
// snappyDecodedLen returns the length of the decoded block and the number of bytes
|
||
|
// that the length header occupied.
|
||
|
func snappyDecodedLen(src []byte) (blockLen, headerLen int, err error) {
|
||
|
v, n := binary.Uvarint(src)
|
||
|
if n <= 0 || v > 0xffffffff {
|
||
|
return 0, 0, ErrSnappyCorrupt
|
||
|
}
|
||
|
|
||
|
const wordSize = 32 << (^uint(0) >> 32 & 1)
|
||
|
if wordSize == 32 && v > 0x7fffffff {
|
||
|
return 0, 0, ErrSnappyTooLarge
|
||
|
}
|
||
|
return int(v), n, nil
|
||
|
}
|