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forgejo/vendor/github.com/klauspost/compress/zstd/dict.go
6543 12a1f914f4
Vendor Update Go Libs (#13166)
* update github.com/alecthomas/chroma v0.8.0 -> v0.8.1

* github.com/blevesearch/bleve v1.0.10 -> v1.0.12

* editorconfig-core-go v2.1.1 -> v2.3.7

* github.com/gliderlabs/ssh v0.2.2 -> v0.3.1

* migrate editorconfig.ParseBytes to Parse

* github.com/shurcooL/vfsgen to 0d455de96546

* github.com/go-git/go-git/v5 v5.1.0 -> v5.2.0

* github.com/google/uuid v1.1.1 -> v1.1.2

* github.com/huandu/xstrings v1.3.0 -> v1.3.2

* github.com/klauspost/compress v1.10.11 -> v1.11.1

* github.com/markbates/goth v1.61.2 -> v1.65.0

* github.com/mattn/go-sqlite3 v1.14.0 -> v1.14.4

* github.com/mholt/archiver v3.3.0 -> v3.3.2

* github.com/microcosm-cc/bluemonday 4f7140c49acb -> v1.0.4

* github.com/minio/minio-go v7.0.4 -> v7.0.5

* github.com/olivere/elastic v7.0.9 -> v7.0.20

* github.com/urfave/cli v1.20.0 -> v1.22.4

* github.com/prometheus/client_golang v1.1.0 -> v1.8.0

* github.com/xanzy/go-gitlab v0.37.0 -> v0.38.1

* mvdan.cc/xurls v2.1.0 -> v2.2.0

Co-authored-by: Lauris BH <lauris@nix.lv>
2020-10-16 01:06:27 -04:00

122 lines
2.8 KiB
Go
Vendored

package zstd
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"github.com/klauspost/compress/huff0"
)
type dict struct {
id uint32
litEnc *huff0.Scratch
llDec, ofDec, mlDec sequenceDec
//llEnc, ofEnc, mlEnc []*fseEncoder
offsets [3]int
content []byte
}
var dictMagic = [4]byte{0x37, 0xa4, 0x30, 0xec}
// ID returns the dictionary id or 0 if d is nil.
func (d *dict) ID() uint32 {
if d == nil {
return 0
}
return d.id
}
// DictContentSize returns the dictionary content size or 0 if d is nil.
func (d *dict) DictContentSize() int {
if d == nil {
return 0
}
return len(d.content)
}
// Load a dictionary as described in
// https://github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md#dictionary-format
func loadDict(b []byte) (*dict, error) {
// Check static field size.
if len(b) <= 8+(3*4) {
return nil, io.ErrUnexpectedEOF
}
d := dict{
llDec: sequenceDec{fse: &fseDecoder{}},
ofDec: sequenceDec{fse: &fseDecoder{}},
mlDec: sequenceDec{fse: &fseDecoder{}},
}
if !bytes.Equal(b[:4], dictMagic[:]) {
return nil, ErrMagicMismatch
}
d.id = binary.LittleEndian.Uint32(b[4:8])
if d.id == 0 {
return nil, errors.New("dictionaries cannot have ID 0")
}
// Read literal table
var err error
d.litEnc, b, err = huff0.ReadTable(b[8:], nil)
if err != nil {
return nil, err
}
d.litEnc.Reuse = huff0.ReusePolicyMust
br := byteReader{
b: b,
off: 0,
}
readDec := func(i tableIndex, dec *fseDecoder) error {
if err := dec.readNCount(&br, uint16(maxTableSymbol[i])); err != nil {
return err
}
if br.overread() {
return io.ErrUnexpectedEOF
}
err = dec.transform(symbolTableX[i])
if err != nil {
println("Transform table error:", err)
return err
}
if debug {
println("Read table ok", "symbolLen:", dec.symbolLen)
}
// Set decoders as predefined so they aren't reused.
dec.preDefined = true
return nil
}
if err := readDec(tableOffsets, d.ofDec.fse); err != nil {
return nil, err
}
if err := readDec(tableMatchLengths, d.mlDec.fse); err != nil {
return nil, err
}
if err := readDec(tableLiteralLengths, d.llDec.fse); err != nil {
return nil, err
}
if br.remain() < 12 {
return nil, io.ErrUnexpectedEOF
}
d.offsets[0] = int(br.Uint32())
br.advance(4)
d.offsets[1] = int(br.Uint32())
br.advance(4)
d.offsets[2] = int(br.Uint32())
br.advance(4)
if d.offsets[0] <= 0 || d.offsets[1] <= 0 || d.offsets[2] <= 0 {
return nil, errors.New("invalid offset in dictionary")
}
d.content = make([]byte, br.remain())
copy(d.content, br.unread())
if d.offsets[0] > len(d.content) || d.offsets[1] > len(d.content) || d.offsets[2] > len(d.content) {
return nil, fmt.Errorf("initial offset bigger than dictionary content size %d, offsets: %v", len(d.content), d.offsets)
}
return &d, nil
}