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authorGravatar Runxi Yu2025-11-19 08:00:00 +0800
committerGravatar Runxi Yu2025-11-19 08:00:00 +0800
commited0a113f034aa42aea23471c4bc0d7af159b7002 (patch)
tree7e828011b9e213499ce382eb17e2552da6e48de4 /internal/zlib/reader.go
parentRemove some redundant code (diff)
signatureNo signature
Probably should name the custom packages specially
Diffstat (limited to 'internal/zlib/reader.go')
-rw-r--r--internal/zlib/reader.go198
1 files changed, 0 insertions, 198 deletions
diff --git a/internal/zlib/reader.go b/internal/zlib/reader.go
deleted file mode 100644
index 2c8fd215..00000000
--- a/internal/zlib/reader.go
+++ /dev/null
@@ -1,198 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-/*
-Package zlib implements reading and writing of zlib format compressed data,
-as specified in RFC 1950.
-
-This package differs from the standard library's compress/zlib package
-in that it pools readers to reduce allocations. Writers are unchanged.
-
-Note that closing the reader causes it to be returned to a pool for
-reuse. Therefore, the caller must not retain references to the
-reader after closing it; in the standard library's compress/zlib package,
-it is legal to Reset a closed reader and continue using it; that is
-not allowed here, so there is simply no Resetter interface.
-
-The implementation provides filters that uncompress during reading
-and compress during writing. For example, to write compressed data
-to a buffer:
-
- var b bytes.Buffer
- w := zlib.NewWriter(&b)
- w.Write([]byte("hello, world\n"))
- w.Close()
-
-and to read that data back:
-
- r, err := zlib.NewReader(&b)
- io.Copy(os.Stdout, r)
- r.Close()
-*/
-package zlib
-
-import (
- "bufio"
- "encoding/binary"
- "errors"
- "hash"
- "io"
- "sync"
-
- "git.sr.ht/~runxiyu/furgit/internal/adler32"
- "git.sr.ht/~runxiyu/furgit/internal/flate"
-)
-
-const (
- zlibDeflate = 8
- zlibMaxWindow = 7
-)
-
-var (
- // ErrChecksum is returned when reading ZLIB data that has an invalid checksum.
- ErrChecksum = errors.New("zlib: invalid checksum")
- // ErrDictionary is returned when reading ZLIB data that has an invalid dictionary.
- ErrDictionary = errors.New("zlib: invalid dictionary")
- // ErrHeader is returned when reading ZLIB data that has an invalid header.
- ErrHeader = errors.New("zlib: invalid header")
-)
-
-var pool = sync.Pool{
- New: func() any {
- r := new(reader)
- return r
- },
-}
-
-type reader struct {
- r flate.Reader
- decompressor io.ReadCloser
- digest hash.Hash32
- err error
- scratch [4]byte
-}
-
-// NewReader creates a new ReadCloser.
-// Reads from the returned ReadCloser read and decompress data from r.
-// If r does not implement [io.ByteReader], the decompressor may read more
-// data than necessary from r.
-// It is the caller's responsibility to call Close on the ReadCloser when done.
-func NewReader(r io.Reader) (io.ReadCloser, error) {
- return NewReaderDict(r, nil)
-}
-
-// NewReaderDict is like [NewReader] but uses a preset dictionary.
-// NewReaderDict ignores the dictionary if the compressed data does not refer to it.
-// If the compressed data refers to a different dictionary, NewReaderDict returns [ErrDictionary].
-func NewReaderDict(r io.Reader, dict []byte) (io.ReadCloser, error) {
- v := pool.Get()
- z, ok := v.(*reader)
- if !ok {
- panic("zlib: pool returned unexpected type")
- }
- err := z.Reset(r, dict)
- if err != nil {
- return nil, err
- }
- return z, nil
-}
-
-func (z *reader) Read(p []byte) (int, error) {
- if z.err != nil {
- return 0, z.err
- }
-
- var n int
- n, z.err = z.decompressor.Read(p)
- z.digest.Write(p[0:n])
- if z.err != io.EOF {
- // In the normal case we return here.
- return n, z.err
- }
-
- // Finished file; check checksum.
- if _, err := io.ReadFull(z.r, z.scratch[0:4]); err != nil {
- if err == io.EOF {
- err = io.ErrUnexpectedEOF
- }
- z.err = err
- return n, z.err
- }
- // ZLIB (RFC 1950) is big-endian, unlike GZIP (RFC 1952).
- checksum := binary.BigEndian.Uint32(z.scratch[:4])
- if checksum != z.digest.Sum32() {
- z.err = ErrChecksum
- return n, z.err
- }
- return n, io.EOF
-}
-
-// Calling Close does not close the wrapped [io.Reader] originally passed to [NewReader].
-// In order for the ZLIB checksum to be verified, the reader must be
-// fully consumed until the [io.EOF].
-func (z *reader) Close() error {
- if z.err != nil && z.err != io.EOF {
- return z.err
- }
- z.err = z.decompressor.Close()
- if z.err != nil {
- return z.err
- }
-
- pool.Put(z)
- return nil
-}
-
-func (z *reader) Reset(r io.Reader, dict []byte) error {
- *z = reader{decompressor: z.decompressor}
- if fr, ok := r.(flate.Reader); ok {
- z.r = fr
- } else {
- z.r = bufio.NewReader(r)
- }
-
- // Read the header (RFC 1950 section 2.2.).
- _, z.err = io.ReadFull(z.r, z.scratch[0:2])
- if z.err != nil {
- if z.err == io.EOF {
- z.err = io.ErrUnexpectedEOF
- }
- return z.err
- }
- h := binary.BigEndian.Uint16(z.scratch[:2])
- if (z.scratch[0]&0x0f != zlibDeflate) || (z.scratch[0]>>4 > zlibMaxWindow) || (h%31 != 0) {
- z.err = ErrHeader
- return z.err
- }
- haveDict := z.scratch[1]&0x20 != 0
- if haveDict {
- _, z.err = io.ReadFull(z.r, z.scratch[0:4])
- if z.err != nil {
- if z.err == io.EOF {
- z.err = io.ErrUnexpectedEOF
- }
- return z.err
- }
- checksum := binary.BigEndian.Uint32(z.scratch[:4])
- if checksum != adler32.Checksum(dict) {
- z.err = ErrDictionary
- return z.err
- }
- }
-
- if z.decompressor == nil {
- if haveDict {
- z.decompressor = flate.NewReaderDict(z.r, dict)
- } else {
- z.decompressor = flate.NewReader(z.r)
- }
- } else {
- z.err = z.decompressor.(flate.Resetter).Reset(z.r, dict)
- if z.err != nil {
- return z.err
- }
- }
- z.digest = adler32.New()
- return nil
-}