727 lines
19 KiB
Go
727 lines
19 KiB
Go
// Copyright 2019+ Klaus Post. All rights reserved.
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// License information can be found in the LICENSE file.
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// Based on work by Yann Collet, released under BSD License.
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package zstd
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"fmt"
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"hash/crc32"
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"io"
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"os"
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"path/filepath"
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"sync"
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"github.com/klauspost/compress/huff0"
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"github.com/klauspost/compress/zstd/internal/xxhash"
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)
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type blockType uint8
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//go:generate stringer -type=blockType,literalsBlockType,seqCompMode,tableIndex
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const (
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blockTypeRaw blockType = iota
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blockTypeRLE
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blockTypeCompressed
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blockTypeReserved
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)
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type literalsBlockType uint8
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const (
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literalsBlockRaw literalsBlockType = iota
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literalsBlockRLE
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literalsBlockCompressed
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literalsBlockTreeless
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)
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const (
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// maxCompressedBlockSize is the biggest allowed compressed block size (128KB)
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maxCompressedBlockSize = 128 << 10
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compressedBlockOverAlloc = 16
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maxCompressedBlockSizeAlloc = 128<<10 + compressedBlockOverAlloc
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// Maximum possible block size (all Raw+Uncompressed).
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maxBlockSize = (1 << 21) - 1
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maxMatchLen = 131074
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maxSequences = 0x7f00 + 0xffff
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// We support slightly less than the reference decoder to be able to
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// use ints on 32 bit archs.
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maxOffsetBits = 30
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)
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var (
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huffDecoderPool = sync.Pool{New: func() interface{} {
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return &huff0.Scratch{}
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}}
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fseDecoderPool = sync.Pool{New: func() interface{} {
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return &fseDecoder{}
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}}
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)
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type blockDec struct {
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// Raw source data of the block.
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data []byte
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dataStorage []byte
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// Destination of the decoded data.
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dst []byte
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// Buffer for literals data.
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literalBuf []byte
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// Window size of the block.
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WindowSize uint64
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err error
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// Check against this crc, if hasCRC is true.
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checkCRC uint32
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hasCRC bool
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// Frame to use for singlethreaded decoding.
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// Should not be used by the decoder itself since parent may be another frame.
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localFrame *frameDec
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sequence []seqVals
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async struct {
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newHist *history
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literals []byte
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seqData []byte
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seqSize int // Size of uncompressed sequences
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fcs uint64
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}
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// Block is RLE, this is the size.
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RLESize uint32
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Type blockType
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// Is this the last block of a frame?
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Last bool
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// Use less memory
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lowMem bool
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}
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func (b *blockDec) String() string {
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if b == nil {
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return "<nil>"
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}
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return fmt.Sprintf("Steam Size: %d, Type: %v, Last: %t, Window: %d", len(b.data), b.Type, b.Last, b.WindowSize)
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}
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func newBlockDec(lowMem bool) *blockDec {
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b := blockDec{
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lowMem: lowMem,
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}
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return &b
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}
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// reset will reset the block.
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// Input must be a start of a block and will be at the end of the block when returned.
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func (b *blockDec) reset(br byteBuffer, windowSize uint64) error {
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b.WindowSize = windowSize
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tmp, err := br.readSmall(3)
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if err != nil {
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println("Reading block header:", err)
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return err
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}
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bh := uint32(tmp[0]) | (uint32(tmp[1]) << 8) | (uint32(tmp[2]) << 16)
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b.Last = bh&1 != 0
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b.Type = blockType((bh >> 1) & 3)
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// find size.
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cSize := int(bh >> 3)
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maxSize := maxCompressedBlockSizeAlloc
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switch b.Type {
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case blockTypeReserved:
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return ErrReservedBlockType
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case blockTypeRLE:
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if cSize > maxCompressedBlockSize || cSize > int(b.WindowSize) {
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if debugDecoder {
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printf("rle block too big: csize:%d block: %+v\n", uint64(cSize), b)
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}
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return ErrWindowSizeExceeded
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}
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b.RLESize = uint32(cSize)
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if b.lowMem {
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maxSize = cSize
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}
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cSize = 1
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case blockTypeCompressed:
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if debugDecoder {
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println("Data size on stream:", cSize)
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}
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b.RLESize = 0
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maxSize = maxCompressedBlockSizeAlloc
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if windowSize < maxCompressedBlockSize && b.lowMem {
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maxSize = int(windowSize) + compressedBlockOverAlloc
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}
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if cSize > maxCompressedBlockSize || uint64(cSize) > b.WindowSize {
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if debugDecoder {
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printf("compressed block too big: csize:%d block: %+v\n", uint64(cSize), b)
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}
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return ErrCompressedSizeTooBig
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}
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// Empty compressed blocks must at least be 2 bytes
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// for Literals_Block_Type and one for Sequences_Section_Header.
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if cSize < 2 {
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return ErrBlockTooSmall
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}
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case blockTypeRaw:
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if cSize > maxCompressedBlockSize || cSize > int(b.WindowSize) {
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if debugDecoder {
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printf("rle block too big: csize:%d block: %+v\n", uint64(cSize), b)
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}
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return ErrWindowSizeExceeded
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}
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b.RLESize = 0
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// We do not need a destination for raw blocks.
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maxSize = -1
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default:
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panic("Invalid block type")
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}
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// Read block data.
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if _, ok := br.(*byteBuf); !ok && cap(b.dataStorage) < cSize {
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// byteBuf doesn't need a destination buffer.
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if b.lowMem || cSize > maxCompressedBlockSize {
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b.dataStorage = make([]byte, 0, cSize+compressedBlockOverAlloc)
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} else {
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b.dataStorage = make([]byte, 0, maxCompressedBlockSizeAlloc)
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}
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}
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b.data, err = br.readBig(cSize, b.dataStorage)
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if err != nil {
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if debugDecoder {
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println("Reading block:", err, "(", cSize, ")", len(b.data))
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printf("%T", br)
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}
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return err
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}
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if cap(b.dst) <= maxSize {
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b.dst = make([]byte, 0, maxSize+1)
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}
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return nil
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}
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// sendEOF will make the decoder send EOF on this frame.
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func (b *blockDec) sendErr(err error) {
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b.Last = true
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b.Type = blockTypeReserved
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b.err = err
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}
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// Close will release resources.
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// Closed blockDec cannot be reset.
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func (b *blockDec) Close() {
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}
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// decodeBuf
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func (b *blockDec) decodeBuf(hist *history) error {
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switch b.Type {
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case blockTypeRLE:
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if cap(b.dst) < int(b.RLESize) {
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if b.lowMem {
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b.dst = make([]byte, b.RLESize)
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} else {
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b.dst = make([]byte, maxCompressedBlockSize)
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}
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}
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b.dst = b.dst[:b.RLESize]
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v := b.data[0]
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for i := range b.dst {
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b.dst[i] = v
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}
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hist.appendKeep(b.dst)
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return nil
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case blockTypeRaw:
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hist.appendKeep(b.data)
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return nil
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case blockTypeCompressed:
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saved := b.dst
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// Append directly to history
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if hist.ignoreBuffer == 0 {
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b.dst = hist.b
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hist.b = nil
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} else {
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b.dst = b.dst[:0]
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}
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err := b.decodeCompressed(hist)
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if debugDecoder {
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println("Decompressed to total", len(b.dst), "bytes, hash:", xxhash.Sum64(b.dst), "error:", err)
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}
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if hist.ignoreBuffer == 0 {
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hist.b = b.dst
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b.dst = saved
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} else {
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hist.appendKeep(b.dst)
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}
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return err
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case blockTypeReserved:
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// Used for returning errors.
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return b.err
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default:
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panic("Invalid block type")
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}
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}
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func (b *blockDec) decodeLiterals(in []byte, hist *history) (remain []byte, err error) {
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// There must be at least one byte for Literals_Block_Type and one for Sequences_Section_Header
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if len(in) < 2 {
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return in, ErrBlockTooSmall
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}
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litType := literalsBlockType(in[0] & 3)
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var litRegenSize int
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var litCompSize int
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sizeFormat := (in[0] >> 2) & 3
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var fourStreams bool
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var literals []byte
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switch litType {
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case literalsBlockRaw, literalsBlockRLE:
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switch sizeFormat {
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case 0, 2:
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// Regenerated_Size uses 5 bits (0-31). Literals_Section_Header uses 1 byte.
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litRegenSize = int(in[0] >> 3)
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in = in[1:]
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case 1:
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// Regenerated_Size uses 12 bits (0-4095). Literals_Section_Header uses 2 bytes.
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litRegenSize = int(in[0]>>4) + (int(in[1]) << 4)
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in = in[2:]
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case 3:
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// Regenerated_Size uses 20 bits (0-1048575). Literals_Section_Header uses 3 bytes.
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if len(in) < 3 {
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println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
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return in, ErrBlockTooSmall
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}
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litRegenSize = int(in[0]>>4) + (int(in[1]) << 4) + (int(in[2]) << 12)
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in = in[3:]
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}
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case literalsBlockCompressed, literalsBlockTreeless:
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switch sizeFormat {
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case 0, 1:
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// Both Regenerated_Size and Compressed_Size use 10 bits (0-1023).
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if len(in) < 3 {
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println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
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return in, ErrBlockTooSmall
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}
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n := uint64(in[0]>>4) + (uint64(in[1]) << 4) + (uint64(in[2]) << 12)
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litRegenSize = int(n & 1023)
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litCompSize = int(n >> 10)
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fourStreams = sizeFormat == 1
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in = in[3:]
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case 2:
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fourStreams = true
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if len(in) < 4 {
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println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
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return in, ErrBlockTooSmall
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}
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n := uint64(in[0]>>4) + (uint64(in[1]) << 4) + (uint64(in[2]) << 12) + (uint64(in[3]) << 20)
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litRegenSize = int(n & 16383)
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litCompSize = int(n >> 14)
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in = in[4:]
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case 3:
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fourStreams = true
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if len(in) < 5 {
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println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
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return in, ErrBlockTooSmall
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}
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n := uint64(in[0]>>4) + (uint64(in[1]) << 4) + (uint64(in[2]) << 12) + (uint64(in[3]) << 20) + (uint64(in[4]) << 28)
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litRegenSize = int(n & 262143)
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litCompSize = int(n >> 18)
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in = in[5:]
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}
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}
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if debugDecoder {
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println("literals type:", litType, "litRegenSize:", litRegenSize, "litCompSize:", litCompSize, "sizeFormat:", sizeFormat, "4X:", fourStreams)
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}
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if litRegenSize > int(b.WindowSize) || litRegenSize > maxCompressedBlockSize {
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return in, ErrWindowSizeExceeded
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}
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switch litType {
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case literalsBlockRaw:
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if len(in) < litRegenSize {
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println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litRegenSize)
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return in, ErrBlockTooSmall
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}
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literals = in[:litRegenSize]
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in = in[litRegenSize:]
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//printf("Found %d uncompressed literals\n", litRegenSize)
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case literalsBlockRLE:
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if len(in) < 1 {
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println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", 1)
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return in, ErrBlockTooSmall
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}
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if cap(b.literalBuf) < litRegenSize {
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if b.lowMem {
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b.literalBuf = make([]byte, litRegenSize, litRegenSize+compressedBlockOverAlloc)
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} else {
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b.literalBuf = make([]byte, litRegenSize, maxCompressedBlockSize+compressedBlockOverAlloc)
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}
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}
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literals = b.literalBuf[:litRegenSize]
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v := in[0]
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for i := range literals {
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literals[i] = v
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}
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in = in[1:]
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if debugDecoder {
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printf("Found %d RLE compressed literals\n", litRegenSize)
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}
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case literalsBlockTreeless:
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if len(in) < litCompSize {
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println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litCompSize)
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return in, ErrBlockTooSmall
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}
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// Store compressed literals, so we defer decoding until we get history.
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literals = in[:litCompSize]
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in = in[litCompSize:]
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if debugDecoder {
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printf("Found %d compressed literals\n", litCompSize)
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}
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huff := hist.huffTree
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if huff == nil {
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return in, errors.New("literal block was treeless, but no history was defined")
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}
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// Ensure we have space to store it.
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if cap(b.literalBuf) < litRegenSize {
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if b.lowMem {
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b.literalBuf = make([]byte, 0, litRegenSize+compressedBlockOverAlloc)
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} else {
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b.literalBuf = make([]byte, 0, maxCompressedBlockSize+compressedBlockOverAlloc)
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}
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}
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var err error
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// Use our out buffer.
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huff.MaxDecodedSize = litRegenSize
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if fourStreams {
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literals, err = huff.Decoder().Decompress4X(b.literalBuf[:0:litRegenSize], literals)
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} else {
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literals, err = huff.Decoder().Decompress1X(b.literalBuf[:0:litRegenSize], literals)
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}
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// Make sure we don't leak our literals buffer
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if err != nil {
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println("decompressing literals:", err)
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return in, err
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}
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if len(literals) != litRegenSize {
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return in, fmt.Errorf("literal output size mismatch want %d, got %d", litRegenSize, len(literals))
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}
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case literalsBlockCompressed:
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if len(in) < litCompSize {
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println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litCompSize)
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return in, ErrBlockTooSmall
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}
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literals = in[:litCompSize]
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in = in[litCompSize:]
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// Ensure we have space to store it.
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if cap(b.literalBuf) < litRegenSize {
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if b.lowMem {
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b.literalBuf = make([]byte, 0, litRegenSize+compressedBlockOverAlloc)
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} else {
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b.literalBuf = make([]byte, 0, maxCompressedBlockSize+compressedBlockOverAlloc)
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}
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}
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huff := hist.huffTree
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if huff == nil || (hist.dict != nil && huff == hist.dict.litEnc) {
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huff = huffDecoderPool.Get().(*huff0.Scratch)
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if huff == nil {
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huff = &huff0.Scratch{}
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}
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}
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var err error
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if debugDecoder {
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println("huff table input:", len(literals), "CRC:", crc32.ChecksumIEEE(literals))
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}
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huff, literals, err = huff0.ReadTable(literals, huff)
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if err != nil {
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println("reading huffman table:", err)
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return in, err
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}
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hist.huffTree = huff
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huff.MaxDecodedSize = litRegenSize
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// Use our out buffer.
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if fourStreams {
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literals, err = huff.Decoder().Decompress4X(b.literalBuf[:0:litRegenSize], literals)
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} else {
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literals, err = huff.Decoder().Decompress1X(b.literalBuf[:0:litRegenSize], literals)
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}
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if err != nil {
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println("decoding compressed literals:", err)
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return in, err
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}
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// Make sure we don't leak our literals buffer
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if len(literals) != litRegenSize {
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return in, fmt.Errorf("literal output size mismatch want %d, got %d", litRegenSize, len(literals))
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}
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// Re-cap to get extra size.
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literals = b.literalBuf[:len(literals)]
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if debugDecoder {
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printf("Decompressed %d literals into %d bytes\n", litCompSize, litRegenSize)
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}
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}
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hist.decoders.literals = literals
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return in, nil
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}
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// decodeCompressed will start decompressing a block.
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func (b *blockDec) decodeCompressed(hist *history) error {
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in := b.data
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in, err := b.decodeLiterals(in, hist)
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if err != nil {
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return err
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}
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err = b.prepareSequences(in, hist)
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if err != nil {
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return err
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}
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if hist.decoders.nSeqs == 0 {
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b.dst = append(b.dst, hist.decoders.literals...)
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return nil
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}
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before := len(hist.decoders.out)
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err = hist.decoders.decodeSync(hist.b[hist.ignoreBuffer:])
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if err != nil {
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return err
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}
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if hist.decoders.maxSyncLen > 0 {
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hist.decoders.maxSyncLen += uint64(before)
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hist.decoders.maxSyncLen -= uint64(len(hist.decoders.out))
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}
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b.dst = hist.decoders.out
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hist.recentOffsets = hist.decoders.prevOffset
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return nil
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}
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func (b *blockDec) prepareSequences(in []byte, hist *history) (err error) {
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if debugDecoder {
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printf("prepareSequences: %d byte(s) input\n", len(in))
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}
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// Decode Sequences
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// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#sequences-section
|
|
if len(in) < 1 {
|
|
return ErrBlockTooSmall
|
|
}
|
|
var nSeqs int
|
|
seqHeader := in[0]
|
|
switch {
|
|
case seqHeader < 128:
|
|
nSeqs = int(seqHeader)
|
|
in = in[1:]
|
|
case seqHeader < 255:
|
|
if len(in) < 2 {
|
|
return ErrBlockTooSmall
|
|
}
|
|
nSeqs = int(seqHeader-128)<<8 | int(in[1])
|
|
in = in[2:]
|
|
case seqHeader == 255:
|
|
if len(in) < 3 {
|
|
return ErrBlockTooSmall
|
|
}
|
|
nSeqs = 0x7f00 + int(in[1]) + (int(in[2]) << 8)
|
|
in = in[3:]
|
|
}
|
|
if nSeqs == 0 && len(in) != 0 {
|
|
// When no sequences, there should not be any more data...
|
|
if debugDecoder {
|
|
printf("prepareSequences: 0 sequences, but %d byte(s) left on stream\n", len(in))
|
|
}
|
|
return ErrUnexpectedBlockSize
|
|
}
|
|
|
|
var seqs = &hist.decoders
|
|
seqs.nSeqs = nSeqs
|
|
if nSeqs > 0 {
|
|
if len(in) < 1 {
|
|
return ErrBlockTooSmall
|
|
}
|
|
br := byteReader{b: in, off: 0}
|
|
compMode := br.Uint8()
|
|
br.advance(1)
|
|
if debugDecoder {
|
|
printf("Compression modes: 0b%b", compMode)
|
|
}
|
|
for i := uint(0); i < 3; i++ {
|
|
mode := seqCompMode((compMode >> (6 - i*2)) & 3)
|
|
if debugDecoder {
|
|
println("Table", tableIndex(i), "is", mode)
|
|
}
|
|
var seq *sequenceDec
|
|
switch tableIndex(i) {
|
|
case tableLiteralLengths:
|
|
seq = &seqs.litLengths
|
|
case tableOffsets:
|
|
seq = &seqs.offsets
|
|
case tableMatchLengths:
|
|
seq = &seqs.matchLengths
|
|
default:
|
|
panic("unknown table")
|
|
}
|
|
switch mode {
|
|
case compModePredefined:
|
|
if seq.fse != nil && !seq.fse.preDefined {
|
|
fseDecoderPool.Put(seq.fse)
|
|
}
|
|
seq.fse = &fsePredef[i]
|
|
case compModeRLE:
|
|
if br.remain() < 1 {
|
|
return ErrBlockTooSmall
|
|
}
|
|
v := br.Uint8()
|
|
br.advance(1)
|
|
if seq.fse == nil || seq.fse.preDefined {
|
|
seq.fse = fseDecoderPool.Get().(*fseDecoder)
|
|
}
|
|
symb, err := decSymbolValue(v, symbolTableX[i])
|
|
if err != nil {
|
|
printf("RLE Transform table (%v) error: %v", tableIndex(i), err)
|
|
return err
|
|
}
|
|
seq.fse.setRLE(symb)
|
|
if debugDecoder {
|
|
printf("RLE set to 0x%x, code: %v", symb, v)
|
|
}
|
|
case compModeFSE:
|
|
println("Reading table for", tableIndex(i))
|
|
if seq.fse == nil || seq.fse.preDefined {
|
|
seq.fse = fseDecoderPool.Get().(*fseDecoder)
|
|
}
|
|
err := seq.fse.readNCount(&br, uint16(maxTableSymbol[i]))
|
|
if err != nil {
|
|
println("Read table error:", err)
|
|
return err
|
|
}
|
|
err = seq.fse.transform(symbolTableX[i])
|
|
if err != nil {
|
|
println("Transform table error:", err)
|
|
return err
|
|
}
|
|
if debugDecoder {
|
|
println("Read table ok", "symbolLen:", seq.fse.symbolLen)
|
|
}
|
|
case compModeRepeat:
|
|
seq.repeat = true
|
|
}
|
|
if br.overread() {
|
|
return io.ErrUnexpectedEOF
|
|
}
|
|
}
|
|
in = br.unread()
|
|
}
|
|
if debugDecoder {
|
|
println("Literals:", len(seqs.literals), "hash:", xxhash.Sum64(seqs.literals), "and", seqs.nSeqs, "sequences.")
|
|
}
|
|
|
|
if nSeqs == 0 {
|
|
if len(b.sequence) > 0 {
|
|
b.sequence = b.sequence[:0]
|
|
}
|
|
return nil
|
|
}
|
|
br := seqs.br
|
|
if br == nil {
|
|
br = &bitReader{}
|
|
}
|
|
if err := br.init(in); err != nil {
|
|
return err
|
|
}
|
|
|
|
if err := seqs.initialize(br, hist, b.dst); err != nil {
|
|
println("initializing sequences:", err)
|
|
return err
|
|
}
|
|
// Extract blocks...
|
|
if false && hist.dict == nil {
|
|
fatalErr := func(err error) {
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
}
|
|
fn := fmt.Sprintf("n-%d-lits-%d-prev-%d-%d-%d-win-%d.blk", hist.decoders.nSeqs, len(hist.decoders.literals), hist.recentOffsets[0], hist.recentOffsets[1], hist.recentOffsets[2], hist.windowSize)
|
|
var buf bytes.Buffer
|
|
fatalErr(binary.Write(&buf, binary.LittleEndian, hist.decoders.litLengths.fse))
|
|
fatalErr(binary.Write(&buf, binary.LittleEndian, hist.decoders.matchLengths.fse))
|
|
fatalErr(binary.Write(&buf, binary.LittleEndian, hist.decoders.offsets.fse))
|
|
buf.Write(in)
|
|
os.WriteFile(filepath.Join("testdata", "seqs", fn), buf.Bytes(), os.ModePerm)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func (b *blockDec) decodeSequences(hist *history) error {
|
|
if cap(b.sequence) < hist.decoders.nSeqs {
|
|
if b.lowMem {
|
|
b.sequence = make([]seqVals, 0, hist.decoders.nSeqs)
|
|
} else {
|
|
b.sequence = make([]seqVals, 0, 0x7F00+0xffff)
|
|
}
|
|
}
|
|
b.sequence = b.sequence[:hist.decoders.nSeqs]
|
|
if hist.decoders.nSeqs == 0 {
|
|
hist.decoders.seqSize = len(hist.decoders.literals)
|
|
return nil
|
|
}
|
|
hist.decoders.windowSize = hist.windowSize
|
|
hist.decoders.prevOffset = hist.recentOffsets
|
|
|
|
err := hist.decoders.decode(b.sequence)
|
|
hist.recentOffsets = hist.decoders.prevOffset
|
|
return err
|
|
}
|
|
|
|
func (b *blockDec) executeSequences(hist *history) error {
|
|
hbytes := hist.b
|
|
if len(hbytes) > hist.windowSize {
|
|
hbytes = hbytes[len(hbytes)-hist.windowSize:]
|
|
// We do not need history anymore.
|
|
if hist.dict != nil {
|
|
hist.dict.content = nil
|
|
}
|
|
}
|
|
hist.decoders.windowSize = hist.windowSize
|
|
hist.decoders.out = b.dst[:0]
|
|
err := hist.decoders.execute(b.sequence, hbytes)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return b.updateHistory(hist)
|
|
}
|
|
|
|
func (b *blockDec) updateHistory(hist *history) error {
|
|
if len(b.data) > maxCompressedBlockSize {
|
|
return fmt.Errorf("compressed block size too large (%d)", len(b.data))
|
|
}
|
|
// Set output and release references.
|
|
b.dst = hist.decoders.out
|
|
hist.recentOffsets = hist.decoders.prevOffset
|
|
|
|
if b.Last {
|
|
// if last block we don't care about history.
|
|
println("Last block, no history returned")
|
|
hist.b = hist.b[:0]
|
|
return nil
|
|
} else {
|
|
hist.append(b.dst)
|
|
if debugDecoder {
|
|
println("Finished block with ", len(b.sequence), "sequences. Added", len(b.dst), "to history, now length", len(hist.b))
|
|
}
|
|
}
|
|
hist.decoders.out, hist.decoders.literals = nil, nil
|
|
|
|
return nil
|
|
}
|