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https://github.com/go-gitea/gitea
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* update macaron to v1.5 of fork * update macaron to v1.5 of fork * test gzip PR * add push method impl to context_tests * use proper gzip commit Co-authored-by: zeripath <art27@cantab.net> Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
105 lines
2.4 KiB
Go
Vendored
105 lines
2.4 KiB
Go
Vendored
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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"io"
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"github.com/klauspost/compress/huff0"
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)
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type dict struct {
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id uint32
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litDec *huff0.Scratch
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llDec, ofDec, mlDec sequenceDec
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offsets [3]int
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content []byte
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}
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var dictMagic = [4]byte{0x37, 0xa4, 0x30, 0xec}
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// Load a dictionary as described in
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// https://github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md#dictionary-format
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func loadDict(b []byte) (*dict, error) {
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// Check static field size.
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if len(b) <= 8+(3*4) {
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return nil, io.ErrUnexpectedEOF
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}
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d := dict{
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llDec: sequenceDec{fse: &fseDecoder{}},
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ofDec: sequenceDec{fse: &fseDecoder{}},
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mlDec: sequenceDec{fse: &fseDecoder{}},
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}
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if !bytes.Equal(b[:4], dictMagic[:]) {
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return nil, ErrMagicMismatch
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}
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d.id = binary.LittleEndian.Uint32(b[4:8])
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if d.id == 0 {
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return nil, errors.New("dictionaries cannot have ID 0")
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}
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// Read literal table
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var err error
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d.litDec, b, err = huff0.ReadTable(b[8:], nil)
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if err != nil {
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return nil, err
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}
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br := byteReader{
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b: b,
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off: 0,
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}
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readDec := func(i tableIndex, dec *fseDecoder) error {
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if err := dec.readNCount(&br, uint16(maxTableSymbol[i])); err != nil {
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return err
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}
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if br.overread() {
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return io.ErrUnexpectedEOF
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}
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err = dec.transform(symbolTableX[i])
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if err != nil {
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println("Transform table error:", err)
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return err
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}
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if debug {
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println("Read table ok", "symbolLen:", dec.symbolLen)
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}
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// Set decoders as predefined so they aren't reused.
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dec.preDefined = true
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return nil
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}
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if err := readDec(tableOffsets, d.ofDec.fse); err != nil {
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return nil, err
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}
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if err := readDec(tableMatchLengths, d.mlDec.fse); err != nil {
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return nil, err
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}
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if err := readDec(tableLiteralLengths, d.llDec.fse); err != nil {
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return nil, err
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}
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if br.remain() < 12 {
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return nil, io.ErrUnexpectedEOF
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}
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d.offsets[0] = int(br.Uint32())
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br.advance(4)
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d.offsets[1] = int(br.Uint32())
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br.advance(4)
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d.offsets[2] = int(br.Uint32())
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br.advance(4)
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if d.offsets[0] <= 0 || d.offsets[1] <= 0 || d.offsets[2] <= 0 {
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return nil, errors.New("invalid offset in dictionary")
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}
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d.content = make([]byte, br.remain())
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copy(d.content, br.unread())
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if d.offsets[0] > len(d.content) || d.offsets[1] > len(d.content) || d.offsets[2] > len(d.content) {
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return nil, fmt.Errorf("initial offset bigger than dictionary content size %d, offsets: %v", len(d.content), d.offsets)
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}
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return &d, nil
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}
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