mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
synced 2024-12-30 07:40:06 +01:00
433 lines
10 KiB
Go
433 lines
10 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"
|
|
"encoding/hex"
|
|
"errors"
|
|
"io"
|
|
|
|
"github.com/klauspost/compress/zstd/internal/xxhash"
|
|
)
|
|
|
|
type frameDec struct {
|
|
o decoderOptions
|
|
crc *xxhash.Digest
|
|
|
|
WindowSize uint64
|
|
|
|
// Frame history passed between blocks
|
|
history history
|
|
|
|
rawInput byteBuffer
|
|
|
|
// Byte buffer that can be reused for small input blocks.
|
|
bBuf byteBuf
|
|
|
|
FrameContentSize uint64
|
|
|
|
DictionaryID uint32
|
|
HasCheckSum bool
|
|
SingleSegment bool
|
|
}
|
|
|
|
const (
|
|
// MinWindowSize is the minimum Window Size, which is 1 KB.
|
|
MinWindowSize = 1 << 10
|
|
|
|
// MaxWindowSize is the maximum encoder window size
|
|
// and the default decoder maximum window size.
|
|
MaxWindowSize = 1 << 29
|
|
)
|
|
|
|
const (
|
|
frameMagic = "\x28\xb5\x2f\xfd"
|
|
skippableFrameMagic = "\x2a\x4d\x18"
|
|
)
|
|
|
|
func newFrameDec(o decoderOptions) *frameDec {
|
|
if o.maxWindowSize > o.maxDecodedSize {
|
|
o.maxWindowSize = o.maxDecodedSize
|
|
}
|
|
d := frameDec{
|
|
o: o,
|
|
}
|
|
return &d
|
|
}
|
|
|
|
// reset will read the frame header and prepare for block decoding.
|
|
// If nothing can be read from the input, io.EOF will be returned.
|
|
// Any other error indicated that the stream contained data, but
|
|
// there was a problem.
|
|
func (d *frameDec) reset(br byteBuffer) error {
|
|
d.HasCheckSum = false
|
|
d.WindowSize = 0
|
|
var signature [4]byte
|
|
for {
|
|
var err error
|
|
// Check if we can read more...
|
|
b, err := br.readSmall(1)
|
|
switch err {
|
|
case io.EOF, io.ErrUnexpectedEOF:
|
|
return io.EOF
|
|
default:
|
|
return err
|
|
case nil:
|
|
signature[0] = b[0]
|
|
}
|
|
// Read the rest, don't allow io.ErrUnexpectedEOF
|
|
b, err = br.readSmall(3)
|
|
switch err {
|
|
case io.EOF:
|
|
return io.EOF
|
|
default:
|
|
return err
|
|
case nil:
|
|
copy(signature[1:], b)
|
|
}
|
|
|
|
if string(signature[1:4]) != skippableFrameMagic || signature[0]&0xf0 != 0x50 {
|
|
if debugDecoder {
|
|
println("Not skippable", hex.EncodeToString(signature[:]), hex.EncodeToString([]byte(skippableFrameMagic)))
|
|
}
|
|
// Break if not skippable frame.
|
|
break
|
|
}
|
|
// Read size to skip
|
|
b, err = br.readSmall(4)
|
|
if err != nil {
|
|
if debugDecoder {
|
|
println("Reading Frame Size", err)
|
|
}
|
|
return err
|
|
}
|
|
n := uint32(b[0]) | (uint32(b[1]) << 8) | (uint32(b[2]) << 16) | (uint32(b[3]) << 24)
|
|
println("Skipping frame with", n, "bytes.")
|
|
err = br.skipN(int64(n))
|
|
if err != nil {
|
|
if debugDecoder {
|
|
println("Reading discarded frame", err)
|
|
}
|
|
return err
|
|
}
|
|
}
|
|
if string(signature[:]) != frameMagic {
|
|
if debugDecoder {
|
|
println("Got magic numbers: ", signature, "want:", []byte(frameMagic))
|
|
}
|
|
return ErrMagicMismatch
|
|
}
|
|
|
|
// Read Frame_Header_Descriptor
|
|
fhd, err := br.readByte()
|
|
if err != nil {
|
|
if debugDecoder {
|
|
println("Reading Frame_Header_Descriptor", err)
|
|
}
|
|
return err
|
|
}
|
|
d.SingleSegment = fhd&(1<<5) != 0
|
|
|
|
if fhd&(1<<3) != 0 {
|
|
return errors.New("reserved bit set on frame header")
|
|
}
|
|
|
|
// Read Window_Descriptor
|
|
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#window_descriptor
|
|
d.WindowSize = 0
|
|
if !d.SingleSegment {
|
|
wd, err := br.readByte()
|
|
if err != nil {
|
|
if debugDecoder {
|
|
println("Reading Window_Descriptor", err)
|
|
}
|
|
return err
|
|
}
|
|
printf("raw: %x, mantissa: %d, exponent: %d\n", wd, wd&7, wd>>3)
|
|
windowLog := 10 + (wd >> 3)
|
|
windowBase := uint64(1) << windowLog
|
|
windowAdd := (windowBase / 8) * uint64(wd&0x7)
|
|
d.WindowSize = windowBase + windowAdd
|
|
}
|
|
|
|
// Read Dictionary_ID
|
|
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#dictionary_id
|
|
d.DictionaryID = 0
|
|
if size := fhd & 3; size != 0 {
|
|
if size == 3 {
|
|
size = 4
|
|
}
|
|
|
|
b, err := br.readSmall(int(size))
|
|
if err != nil {
|
|
println("Reading Dictionary_ID", err)
|
|
return err
|
|
}
|
|
var id uint32
|
|
switch len(b) {
|
|
case 1:
|
|
id = uint32(b[0])
|
|
case 2:
|
|
id = uint32(b[0]) | (uint32(b[1]) << 8)
|
|
case 4:
|
|
id = uint32(b[0]) | (uint32(b[1]) << 8) | (uint32(b[2]) << 16) | (uint32(b[3]) << 24)
|
|
}
|
|
if debugDecoder {
|
|
println("Dict size", size, "ID:", id)
|
|
}
|
|
d.DictionaryID = id
|
|
}
|
|
|
|
// Read Frame_Content_Size
|
|
// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#frame_content_size
|
|
var fcsSize int
|
|
v := fhd >> 6
|
|
switch v {
|
|
case 0:
|
|
if d.SingleSegment {
|
|
fcsSize = 1
|
|
}
|
|
default:
|
|
fcsSize = 1 << v
|
|
}
|
|
d.FrameContentSize = fcsUnknown
|
|
if fcsSize > 0 {
|
|
b, err := br.readSmall(fcsSize)
|
|
if err != nil {
|
|
println("Reading Frame content", err)
|
|
return err
|
|
}
|
|
switch len(b) {
|
|
case 1:
|
|
d.FrameContentSize = uint64(b[0])
|
|
case 2:
|
|
// When FCS_Field_Size is 2, the offset of 256 is added.
|
|
d.FrameContentSize = uint64(b[0]) | (uint64(b[1]) << 8) + 256
|
|
case 4:
|
|
d.FrameContentSize = uint64(b[0]) | (uint64(b[1]) << 8) | (uint64(b[2]) << 16) | (uint64(b[3]) << 24)
|
|
case 8:
|
|
d1 := uint32(b[0]) | (uint32(b[1]) << 8) | (uint32(b[2]) << 16) | (uint32(b[3]) << 24)
|
|
d2 := uint32(b[4]) | (uint32(b[5]) << 8) | (uint32(b[6]) << 16) | (uint32(b[7]) << 24)
|
|
d.FrameContentSize = uint64(d1) | (uint64(d2) << 32)
|
|
}
|
|
if debugDecoder {
|
|
println("Read FCS:", d.FrameContentSize)
|
|
}
|
|
}
|
|
|
|
// Move this to shared.
|
|
d.HasCheckSum = fhd&(1<<2) != 0
|
|
if d.HasCheckSum {
|
|
if d.crc == nil {
|
|
d.crc = xxhash.New()
|
|
}
|
|
d.crc.Reset()
|
|
}
|
|
|
|
if d.WindowSize > d.o.maxWindowSize {
|
|
if debugDecoder {
|
|
printf("window size %d > max %d\n", d.WindowSize, d.o.maxWindowSize)
|
|
}
|
|
return ErrWindowSizeExceeded
|
|
}
|
|
|
|
if d.WindowSize == 0 && d.SingleSegment {
|
|
// We may not need window in this case.
|
|
d.WindowSize = d.FrameContentSize
|
|
if d.WindowSize < MinWindowSize {
|
|
d.WindowSize = MinWindowSize
|
|
}
|
|
if d.WindowSize > d.o.maxDecodedSize {
|
|
if debugDecoder {
|
|
printf("window size %d > max %d\n", d.WindowSize, d.o.maxWindowSize)
|
|
}
|
|
return ErrDecoderSizeExceeded
|
|
}
|
|
}
|
|
|
|
// The minimum Window_Size is 1 KB.
|
|
if d.WindowSize < MinWindowSize {
|
|
if debugDecoder {
|
|
println("got window size: ", d.WindowSize)
|
|
}
|
|
return ErrWindowSizeTooSmall
|
|
}
|
|
d.history.windowSize = int(d.WindowSize)
|
|
if !d.o.lowMem || d.history.windowSize < maxBlockSize {
|
|
// Alloc 2x window size if not low-mem, or window size below 2MB.
|
|
d.history.allocFrameBuffer = d.history.windowSize * 2
|
|
} else {
|
|
if d.o.lowMem {
|
|
// Alloc with 1MB extra.
|
|
d.history.allocFrameBuffer = d.history.windowSize + maxBlockSize/2
|
|
} else {
|
|
// Alloc with 2MB extra.
|
|
d.history.allocFrameBuffer = d.history.windowSize + maxBlockSize
|
|
}
|
|
}
|
|
|
|
if debugDecoder {
|
|
println("Frame: Dict:", d.DictionaryID, "FrameContentSize:", d.FrameContentSize, "singleseg:", d.SingleSegment, "window:", d.WindowSize, "crc:", d.HasCheckSum)
|
|
}
|
|
|
|
// history contains input - maybe we do something
|
|
d.rawInput = br
|
|
return nil
|
|
}
|
|
|
|
// next will start decoding the next block from stream.
|
|
func (d *frameDec) next(block *blockDec) error {
|
|
if debugDecoder {
|
|
println("decoding new block")
|
|
}
|
|
err := block.reset(d.rawInput, d.WindowSize)
|
|
if err != nil {
|
|
println("block error:", err)
|
|
// Signal the frame decoder we have a problem.
|
|
block.sendErr(err)
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// checkCRC will check the checksum if the frame has one.
|
|
// Will return ErrCRCMismatch if crc check failed, otherwise nil.
|
|
func (d *frameDec) checkCRC() error {
|
|
if !d.HasCheckSum {
|
|
return nil
|
|
}
|
|
|
|
// We can overwrite upper tmp now
|
|
buf, err := d.rawInput.readSmall(4)
|
|
if err != nil {
|
|
println("CRC missing?", err)
|
|
return err
|
|
}
|
|
|
|
if d.o.ignoreChecksum {
|
|
return nil
|
|
}
|
|
|
|
want := binary.LittleEndian.Uint32(buf[:4])
|
|
got := uint32(d.crc.Sum64())
|
|
|
|
if got != want {
|
|
if debugDecoder {
|
|
printf("CRC check failed: got %08x, want %08x\n", got, want)
|
|
}
|
|
return ErrCRCMismatch
|
|
}
|
|
if debugDecoder {
|
|
printf("CRC ok %08x\n", got)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// consumeCRC reads the checksum data if the frame has one.
|
|
func (d *frameDec) consumeCRC() error {
|
|
if d.HasCheckSum {
|
|
_, err := d.rawInput.readSmall(4)
|
|
if err != nil {
|
|
println("CRC missing?", err)
|
|
return err
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// runDecoder will run the decoder for the remainder of the frame.
|
|
func (d *frameDec) runDecoder(dst []byte, dec *blockDec) ([]byte, error) {
|
|
saved := d.history.b
|
|
|
|
// We use the history for output to avoid copying it.
|
|
d.history.b = dst
|
|
d.history.ignoreBuffer = len(dst)
|
|
// Store input length, so we only check new data.
|
|
crcStart := len(dst)
|
|
d.history.decoders.maxSyncLen = 0
|
|
if d.o.limitToCap {
|
|
d.history.decoders.maxSyncLen = uint64(cap(dst) - len(dst))
|
|
}
|
|
if d.FrameContentSize != fcsUnknown {
|
|
if !d.o.limitToCap || d.FrameContentSize+uint64(len(dst)) < d.history.decoders.maxSyncLen {
|
|
d.history.decoders.maxSyncLen = d.FrameContentSize + uint64(len(dst))
|
|
}
|
|
if d.history.decoders.maxSyncLen > d.o.maxDecodedSize {
|
|
if debugDecoder {
|
|
println("maxSyncLen:", d.history.decoders.maxSyncLen, "> maxDecodedSize:", d.o.maxDecodedSize)
|
|
}
|
|
return dst, ErrDecoderSizeExceeded
|
|
}
|
|
if debugDecoder {
|
|
println("maxSyncLen:", d.history.decoders.maxSyncLen)
|
|
}
|
|
if !d.o.limitToCap && uint64(cap(dst)) < d.history.decoders.maxSyncLen {
|
|
// Alloc for output
|
|
dst2 := make([]byte, len(dst), d.history.decoders.maxSyncLen+compressedBlockOverAlloc)
|
|
copy(dst2, dst)
|
|
dst = dst2
|
|
}
|
|
}
|
|
var err error
|
|
for {
|
|
err = dec.reset(d.rawInput, d.WindowSize)
|
|
if err != nil {
|
|
break
|
|
}
|
|
if debugDecoder {
|
|
println("next block:", dec)
|
|
}
|
|
err = dec.decodeBuf(&d.history)
|
|
if err != nil {
|
|
break
|
|
}
|
|
if uint64(len(d.history.b)-crcStart) > d.o.maxDecodedSize {
|
|
println("runDecoder: maxDecodedSize exceeded", uint64(len(d.history.b)-crcStart), ">", d.o.maxDecodedSize)
|
|
err = ErrDecoderSizeExceeded
|
|
break
|
|
}
|
|
if d.o.limitToCap && len(d.history.b) > cap(dst) {
|
|
println("runDecoder: cap exceeded", uint64(len(d.history.b)), ">", cap(dst))
|
|
err = ErrDecoderSizeExceeded
|
|
break
|
|
}
|
|
if uint64(len(d.history.b)-crcStart) > d.FrameContentSize {
|
|
println("runDecoder: FrameContentSize exceeded", uint64(len(d.history.b)-crcStart), ">", d.FrameContentSize)
|
|
err = ErrFrameSizeExceeded
|
|
break
|
|
}
|
|
if dec.Last {
|
|
break
|
|
}
|
|
if debugDecoder {
|
|
println("runDecoder: FrameContentSize", uint64(len(d.history.b)-crcStart), "<=", d.FrameContentSize)
|
|
}
|
|
}
|
|
dst = d.history.b
|
|
if err == nil {
|
|
if d.FrameContentSize != fcsUnknown && uint64(len(d.history.b)-crcStart) != d.FrameContentSize {
|
|
err = ErrFrameSizeMismatch
|
|
} else if d.HasCheckSum {
|
|
if d.o.ignoreChecksum {
|
|
err = d.consumeCRC()
|
|
} else {
|
|
var n int
|
|
n, err = d.crc.Write(dst[crcStart:])
|
|
if err == nil {
|
|
if n != len(dst)-crcStart {
|
|
err = io.ErrShortWrite
|
|
} else {
|
|
err = d.checkCRC()
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
d.history.b = saved
|
|
return dst, err
|
|
}
|