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Diffstat (limited to 'internal/zlib/reader.go')
| -rw-r--r-- | internal/zlib/reader.go | 205 |
1 files changed, 0 insertions, 205 deletions
diff --git a/internal/zlib/reader.go b/internal/zlib/reader.go deleted file mode 100644 index c1e26aae..00000000 --- a/internal/zlib/reader.go +++ /dev/null @@ -1,205 +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 and writers to reduce allocations. - -Note that closing a reader or writer causes it to be returned to a pool -for reuse. Therefore, the caller must not retain references to a -reader or writer after closing it; in the standard library's -compress/zlib package, it is legal to Reset a closed reader or writer -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 ( - "encoding/binary" - "errors" - "hash" - "io" - "sync" - - "github.com/klauspost/compress/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 readerPool = sync.Pool{ - New: func() any { - r := new(Reader) - - return r - }, -} - -// Reader reads and verifies one zlib stream. -// -// Reader implements io.ReadCloser. -type Reader struct { - r flate.Reader - decompressor io.ReadCloser - digest hash.Hash32 - counter *countingFlateReader - err error - scratch [4]byte -} - -// countingFlateReader wraps flate input and tracks consumed bytes. -type countingFlateReader struct { - inner flate.Reader - read uint64 -} - -// Read implements io.Reader. -func (reader *countingFlateReader) Read(dst []byte) (int, error) { - n, err := reader.inner.Read(dst) - reader.read += uint64(n) - - return n, err -} - -// ReadByte implements io.ByteReader. -func (reader *countingFlateReader) ReadByte() (byte, error) { - b, err := reader.inner.ReadByte() - if err == nil { - reader.read++ - } - - return b, err -} - -// 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) (*Reader, 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) (*Reader, error) { - v := readerPool.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 -} - -// Read decompresses bytes from receiver into p. -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) - - _, err := z.digest.Write(p[0:n]) - if err != nil { - z.err = err - - return n, z.err - } - - if !errors.Is(z.err, io.EOF) { - // In the normal case we return here. - return n, z.err - } - - // Finished file; check checksum. - _, err = io.ReadFull(z.r, z.scratch[0:4]) - if err != nil { - if errors.Is(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 -} - -// InputConsumed returns compressed bytes consumed from stream input. -// -// This count includes the zlib header, deflate payload, and zlib checksum -// trailer bytes read by the reader. -func (z *Reader) InputConsumed() uint64 { - if z.counter == nil { - return 0 - } - - return z.counter.read -} - -// 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]. -// Close returns the instance to a global pool; you MUST NOT keep references after Close. -func (z *Reader) Close() error { - if z.err != nil && !errors.Is(z.err, io.EOF) { - return z.err - } - - z.err = z.decompressor.Close() - if z.err != nil { - return z.err - } - - readerPool.Put(z) - - return nil -} |