[chore]: Bump github.com/minio/minio-go/v7 from 7.0.53 to 7.0.55 (#1844)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

1 files changed, 1020 insertions, 0 deletions

diff --git a/vendor/github.com/klauspost/compress/s2/writer.go b/vendor/github.com/klauspost/compress/s2/writer.go
new file mode 100644
index 000000000..5a944068c
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/s2/writer.go
@@ -0,0 +1,1020 @@
+// Copyright 2011 The Snappy-Go Authors. All rights reserved.
+// Copyright (c) 2019+ Klaus Post. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package s2
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"runtime"
+	"sync"
+)
+
+const (
+	levelUncompressed = iota + 1
+	levelFast
+	levelBetter
+	levelBest
+)
+
+// NewWriter returns a new Writer that compresses to w, using the
+// framing format described at
+// https://github.com/google/snappy/blob/master/framing_format.txt
+//
+// Users must call Close to guarantee all data has been forwarded to
+// the underlying io.Writer and that resources are released.
+// They may also call Flush zero or more times before calling Close.
+func NewWriter(w io.Writer, opts ...WriterOption) *Writer {
+	w2 := Writer{
+		blockSize:   defaultBlockSize,
+		concurrency: runtime.GOMAXPROCS(0),
+		randSrc:     rand.Reader,
+		level:       levelFast,
+	}
+	for _, opt := range opts {
+		if err := opt(&w2); err != nil {
+			w2.errState = err
+			return &w2
+		}
+	}
+	w2.obufLen = obufHeaderLen + MaxEncodedLen(w2.blockSize)
+	w2.paramsOK = true
+	w2.ibuf = make([]byte, 0, w2.blockSize)
+	w2.buffers.New = func() interface{} {
+		return make([]byte, w2.obufLen)
+	}
+	w2.Reset(w)
+	return &w2
+}
+
+// Writer is an io.Writer that can write Snappy-compressed bytes.
+type Writer struct {
+	errMu    sync.Mutex
+	errState error
+
+	// ibuf is a buffer for the incoming (uncompressed) bytes.
+	ibuf []byte
+
+	blockSize     int
+	obufLen       int
+	concurrency   int
+	written       int64
+	uncompWritten int64 // Bytes sent to compression
+	output        chan chan result
+	buffers       sync.Pool
+	pad           int
+
+	writer    io.Writer
+	randSrc   io.Reader
+	writerWg  sync.WaitGroup
+	index     Index
+	customEnc func(dst, src []byte) int
+
+	// wroteStreamHeader is whether we have written the stream header.
+	wroteStreamHeader bool
+	paramsOK          bool
+	snappy            bool
+	flushOnWrite      bool
+	appendIndex       bool
+	level             uint8
+}
+
+type result struct {
+	b []byte
+	// Uncompressed start offset
+	startOffset int64
+}
+
+// err returns the previously set error.
+// If no error has been set it is set to err if not nil.
+func (w *Writer) err(err error) error {
+	w.errMu.Lock()
+	errSet := w.errState
+	if errSet == nil && err != nil {
+		w.errState = err
+		errSet = err
+	}
+	w.errMu.Unlock()
+	return errSet
+}
+
+// Reset discards the writer's state and switches the Snappy writer to write to w.
+// This permits reusing a Writer rather than allocating a new one.
+func (w *Writer) Reset(writer io.Writer) {
+	if !w.paramsOK {
+		return
+	}
+	// Close previous writer, if any.
+	if w.output != nil {
+		close(w.output)
+		w.writerWg.Wait()
+		w.output = nil
+	}
+	w.errState = nil
+	w.ibuf = w.ibuf[:0]
+	w.wroteStreamHeader = false
+	w.written = 0
+	w.writer = writer
+	w.uncompWritten = 0
+	w.index.reset(w.blockSize)
+
+	// If we didn't get a writer, stop here.
+	if writer == nil {
+		return
+	}
+	// If no concurrency requested, don't spin up writer goroutine.
+	if w.concurrency == 1 {
+		return
+	}
+
+	toWrite := make(chan chan result, w.concurrency)
+	w.output = toWrite
+	w.writerWg.Add(1)
+
+	// Start a writer goroutine that will write all output in order.
+	go func() {
+		defer w.writerWg.Done()
+
+		// Get a queued write.
+		for write := range toWrite {
+			// Wait for the data to be available.
+			input := <-write
+			in := input.b
+			if len(in) > 0 {
+				if w.err(nil) == nil {
+					// Don't expose data from previous buffers.
+					toWrite := in[:len(in):len(in)]
+					// Write to output.
+					n, err := writer.Write(toWrite)
+					if err == nil && n != len(toWrite) {
+						err = io.ErrShortBuffer
+					}
+					_ = w.err(err)
+					w.err(w.index.add(w.written, input.startOffset))
+					w.written += int64(n)
+				}
+			}
+			if cap(in) >= w.obufLen {
+				w.buffers.Put(in)
+			}
+			// close the incoming write request.
+			// This can be used for synchronizing flushes.
+			close(write)
+		}
+	}()
+}
+
+// Write satisfies the io.Writer interface.
+func (w *Writer) Write(p []byte) (nRet int, errRet error) {
+	if err := w.err(nil); err != nil {
+		return 0, err
+	}
+	if w.flushOnWrite {
+		return w.write(p)
+	}
+	// If we exceed the input buffer size, start writing
+	for len(p) > (cap(w.ibuf)-len(w.ibuf)) && w.err(nil) == nil {
+		var n int
+		if len(w.ibuf) == 0 {
+			// Large write, empty buffer.
+			// Write directly from p to avoid copy.
+			n, _ = w.write(p)
+		} else {
+			n = copy(w.ibuf[len(w.ibuf):cap(w.ibuf)], p)
+			w.ibuf = w.ibuf[:len(w.ibuf)+n]
+			w.write(w.ibuf)
+			w.ibuf = w.ibuf[:0]
+		}
+		nRet += n
+		p = p[n:]
+	}
+	if err := w.err(nil); err != nil {
+		return nRet, err
+	}
+	// p should always be able to fit into w.ibuf now.
+	n := copy(w.ibuf[len(w.ibuf):cap(w.ibuf)], p)
+	w.ibuf = w.ibuf[:len(w.ibuf)+n]
+	nRet += n
+	return nRet, nil
+}
+
+// ReadFrom implements the io.ReaderFrom interface.
+// Using this is typically more efficient since it avoids a memory copy.
+// ReadFrom reads data from r until EOF or error.
+// The return value n is the number of bytes read.
+// Any error except io.EOF encountered during the read is also returned.
+func (w *Writer) ReadFrom(r io.Reader) (n int64, err error) {
+	if err := w.err(nil); err != nil {
+		return 0, err
+	}
+	if len(w.ibuf) > 0 {
+		err := w.Flush()
+		if err != nil {
+			return 0, err
+		}
+	}
+	if br, ok := r.(byter); ok {
+		buf := br.Bytes()
+		if err := w.EncodeBuffer(buf); err != nil {
+			return 0, err
+		}
+		return int64(len(buf)), w.Flush()
+	}
+	for {
+		inbuf := w.buffers.Get().([]byte)[:w.blockSize+obufHeaderLen]
+		n2, err := io.ReadFull(r, inbuf[obufHeaderLen:])
+		if err != nil {
+			if err == io.ErrUnexpectedEOF {
+				err = io.EOF
+			}
+			if err != io.EOF {
+				return n, w.err(err)
+			}
+		}
+		if n2 == 0 {
+			break
+		}
+		n += int64(n2)
+		err2 := w.writeFull(inbuf[:n2+obufHeaderLen])
+		if w.err(err2) != nil {
+			break
+		}
+
+		if err != nil {
+			// We got EOF and wrote everything
+			break
+		}
+	}
+
+	return n, w.err(nil)
+}
+
+// AddSkippableBlock will add a skippable block to the stream.
+// The ID must be 0x80-0xfe (inclusive).
+// Length of the skippable block must be <= 16777215 bytes.
+func (w *Writer) AddSkippableBlock(id uint8, data []byte) (err error) {
+	if err := w.err(nil); err != nil {
+		return err
+	}
+	if len(data) == 0 {
+		return nil
+	}
+	if id < 0x80 || id > chunkTypePadding {
+		return fmt.Errorf("invalid skippable block id %x", id)
+	}
+	if len(data) > maxChunkSize {
+		return fmt.Errorf("skippable block excessed maximum size")
+	}
+	var header [4]byte
+	chunkLen := 4 + len(data)
+	header[0] = id
+	header[1] = uint8(chunkLen >> 0)
+	header[2] = uint8(chunkLen >> 8)
+	header[3] = uint8(chunkLen >> 16)
+	if w.concurrency == 1 {
+		write := func(b []byte) error {
+			n, err := w.writer.Write(b)
+			if err = w.err(err); err != nil {
+				return err
+			}
+			if n != len(data) {
+				return w.err(io.ErrShortWrite)
+			}
+			w.written += int64(n)
+			return w.err(nil)
+		}
+		if !w.wroteStreamHeader {
+			w.wroteStreamHeader = true
+			if w.snappy {
+				if err := write([]byte(magicChunkSnappy)); err != nil {
+					return err
+				}
+			} else {
+				if err := write([]byte(magicChunk)); err != nil {
+					return err
+				}
+			}
+		}
+		if err := write(header[:]); err != nil {
+			return err
+		}
+		if err := write(data); err != nil {
+			return err
+		}
+	}
+
+	// Create output...
+	if !w.wroteStreamHeader {
+		w.wroteStreamHeader = true
+		hWriter := make(chan result)
+		w.output <- hWriter
+		if w.snappy {
+			hWriter <- result{startOffset: w.uncompWritten, b: []byte(magicChunkSnappy)}
+		} else {
+			hWriter <- result{startOffset: w.uncompWritten, b: []byte(magicChunk)}
+		}
+	}
+
+	// Copy input.
+	inbuf := w.buffers.Get().([]byte)[:4]
+	copy(inbuf, header[:])
+	inbuf = append(inbuf, data...)
+
+	output := make(chan result, 1)
+	// Queue output.
+	w.output <- output
+	output <- result{startOffset: w.uncompWritten, b: inbuf}
+
+	return nil
+}
+
+// EncodeBuffer will add a buffer to the stream.
+// This is the fastest way to encode a stream,
+// but the input buffer cannot be written to by the caller
+// until Flush or Close has been called when concurrency != 1.
+//
+// If you cannot control that, use the regular Write function.
+//
+// Note that input is not buffered.
+// This means that each write will result in discrete blocks being created.
+// For buffered writes, use the regular Write function.
+func (w *Writer) EncodeBuffer(buf []byte) (err error) {
+	if err := w.err(nil); err != nil {
+		return err
+	}
+
+	if w.flushOnWrite {
+		_, err := w.write(buf)
+		return err
+	}
+	// Flush queued data first.
+	if len(w.ibuf) > 0 {
+		err := w.Flush()
+		if err != nil {
+			return err
+		}
+	}
+	if w.concurrency == 1 {
+		_, err := w.writeSync(buf)
+		return err
+	}
+
+	// Spawn goroutine and write block to output channel.
+	if !w.wroteStreamHeader {
+		w.wroteStreamHeader = true
+		hWriter := make(chan result)
+		w.output <- hWriter
+		if w.snappy {
+			hWriter <- result{startOffset: w.uncompWritten, b: []byte(magicChunkSnappy)}
+		} else {
+			hWriter <- result{startOffset: w.uncompWritten, b: []byte(magicChunk)}
+		}
+	}
+
+	for len(buf) > 0 {
+		// Cut input.
+		uncompressed := buf
+		if len(uncompressed) > w.blockSize {
+			uncompressed = uncompressed[:w.blockSize]
+		}
+		buf = buf[len(uncompressed):]
+		// Get an output buffer.
+		obuf := w.buffers.Get().([]byte)[:len(uncompressed)+obufHeaderLen]
+		output := make(chan result)
+		// Queue output now, so we keep order.
+		w.output <- output
+		res := result{
+			startOffset: w.uncompWritten,
+		}
+		w.uncompWritten += int64(len(uncompressed))
+		go func() {
+			checksum := crc(uncompressed)
+
+			// Set to uncompressed.
+			chunkType := uint8(chunkTypeUncompressedData)
+			chunkLen := 4 + len(uncompressed)
+
+			// Attempt compressing.
+			n := binary.PutUvarint(obuf[obufHeaderLen:], uint64(len(uncompressed)))
+			n2 := w.encodeBlock(obuf[obufHeaderLen+n:], uncompressed)
+
+			// Check if we should use this, or store as uncompressed instead.
+			if n2 > 0 {
+				chunkType = uint8(chunkTypeCompressedData)
+				chunkLen = 4 + n + n2
+				obuf = obuf[:obufHeaderLen+n+n2]
+			} else {
+				// copy uncompressed
+				copy(obuf[obufHeaderLen:], uncompressed)
+			}
+
+			// Fill in the per-chunk header that comes before the body.
+			obuf[0] = chunkType
+			obuf[1] = uint8(chunkLen >> 0)
+			obuf[2] = uint8(chunkLen >> 8)
+			obuf[3] = uint8(chunkLen >> 16)
+			obuf[4] = uint8(checksum >> 0)
+			obuf[5] = uint8(checksum >> 8)
+			obuf[6] = uint8(checksum >> 16)
+			obuf[7] = uint8(checksum >> 24)
+
+			// Queue final output.
+			res.b = obuf
+			output <- res
+		}()
+	}
+	return nil
+}
+
+func (w *Writer) encodeBlock(obuf, uncompressed []byte) int {
+	if w.customEnc != nil {
+		if ret := w.customEnc(obuf, uncompressed); ret >= 0 {
+			return ret
+		}
+	}
+	if w.snappy {
+		switch w.level {
+		case levelFast:
+			return encodeBlockSnappy(obuf, uncompressed)
+		case levelBetter:
+			return encodeBlockBetterSnappy(obuf, uncompressed)
+		case levelBest:
+			return encodeBlockBestSnappy(obuf, uncompressed)
+		}
+		return 0
+	}
+	switch w.level {
+	case levelFast:
+		return encodeBlock(obuf, uncompressed)
+	case levelBetter:
+		return encodeBlockBetter(obuf, uncompressed)
+	case levelBest:
+		return encodeBlockBest(obuf, uncompressed, nil)
+	}
+	return 0
+}
+
+func (w *Writer) write(p []byte) (nRet int, errRet error) {
+	if err := w.err(nil); err != nil {
+		return 0, err
+	}
+	if w.concurrency == 1 {
+		return w.writeSync(p)
+	}
+
+	// Spawn goroutine and write block to output channel.
+	for len(p) > 0 {
+		if !w.wroteStreamHeader {
+			w.wroteStreamHeader = true
+			hWriter := make(chan result)
+			w.output <- hWriter
+			if w.snappy {
+				hWriter <- result{startOffset: w.uncompWritten, b: []byte(magicChunkSnappy)}
+			} else {
+				hWriter <- result{startOffset: w.uncompWritten, b: []byte(magicChunk)}
+			}
+		}
+
+		var uncompressed []byte
+		if len(p) > w.blockSize {
+			uncompressed, p = p[:w.blockSize], p[w.blockSize:]
+		} else {
+			uncompressed, p = p, nil
+		}
+
+		// Copy input.
+		// If the block is incompressible, this is used for the result.
+		inbuf := w.buffers.Get().([]byte)[:len(uncompressed)+obufHeaderLen]
+		obuf := w.buffers.Get().([]byte)[:w.obufLen]
+		copy(inbuf[obufHeaderLen:], uncompressed)
+		uncompressed = inbuf[obufHeaderLen:]
+
+		output := make(chan result)
+		// Queue output now, so we keep order.
+		w.output <- output
+		res := result{
+			startOffset: w.uncompWritten,
+		}
+		w.uncompWritten += int64(len(uncompressed))
+
+		go func() {
+			checksum := crc(uncompressed)
+
+			// Set to uncompressed.
+			chunkType := uint8(chunkTypeUncompressedData)
+			chunkLen := 4 + len(uncompressed)
+
+			// Attempt compressing.
+			n := binary.PutUvarint(obuf[obufHeaderLen:], uint64(len(uncompressed)))
+			n2 := w.encodeBlock(obuf[obufHeaderLen+n:], uncompressed)
+
+			// Check if we should use this, or store as uncompressed instead.
+			if n2 > 0 {
+				chunkType = uint8(chunkTypeCompressedData)
+				chunkLen = 4 + n + n2
+				obuf = obuf[:obufHeaderLen+n+n2]
+			} else {
+				// Use input as output.
+				obuf, inbuf = inbuf, obuf
+			}
+
+			// Fill in the per-chunk header that comes before the body.
+			obuf[0] = chunkType
+			obuf[1] = uint8(chunkLen >> 0)
+			obuf[2] = uint8(chunkLen >> 8)
+			obuf[3] = uint8(chunkLen >> 16)
+			obuf[4] = uint8(checksum >> 0)
+			obuf[5] = uint8(checksum >> 8)
+			obuf[6] = uint8(checksum >> 16)
+			obuf[7] = uint8(checksum >> 24)
+
+			// Queue final output.
+			res.b = obuf
+			output <- res
+
+			// Put unused buffer back in pool.
+			w.buffers.Put(inbuf)
+		}()
+		nRet += len(uncompressed)
+	}
+	return nRet, nil
+}
+
+// writeFull is a special version of write that will always write the full buffer.
+// Data to be compressed should start at offset obufHeaderLen and fill the remainder of the buffer.
+// The data will be written as a single block.
+// The caller is not allowed to use inbuf after this function has been called.
+func (w *Writer) writeFull(inbuf []byte) (errRet error) {
+	if err := w.err(nil); err != nil {
+		return err
+	}
+
+	if w.concurrency == 1 {
+		_, err := w.writeSync(inbuf[obufHeaderLen:])
+		return err
+	}
+
+	// Spawn goroutine and write block to output channel.
+	if !w.wroteStreamHeader {
+		w.wroteStreamHeader = true
+		hWriter := make(chan result)
+		w.output <- hWriter
+		if w.snappy {
+			hWriter <- result{startOffset: w.uncompWritten, b: []byte(magicChunkSnappy)}
+		} else {
+			hWriter <- result{startOffset: w.uncompWritten, b: []byte(magicChunk)}
+		}
+	}
+
+	// Get an output buffer.
+	obuf := w.buffers.Get().([]byte)[:w.obufLen]
+	uncompressed := inbuf[obufHeaderLen:]
+
+	output := make(chan result)
+	// Queue output now, so we keep order.
+	w.output <- output
+	res := result{
+		startOffset: w.uncompWritten,
+	}
+	w.uncompWritten += int64(len(uncompressed))
+
+	go func() {
+		checksum := crc(uncompressed)
+
+		// Set to uncompressed.
+		chunkType := uint8(chunkTypeUncompressedData)
+		chunkLen := 4 + len(uncompressed)
+
+		// Attempt compressing.
+		n := binary.PutUvarint(obuf[obufHeaderLen:], uint64(len(uncompressed)))
+		n2 := w.encodeBlock(obuf[obufHeaderLen+n:], uncompressed)
+
+		// Check if we should use this, or store as uncompressed instead.
+		if n2 > 0 {
+			chunkType = uint8(chunkTypeCompressedData)
+			chunkLen = 4 + n + n2
+			obuf = obuf[:obufHeaderLen+n+n2]
+		} else {
+			// Use input as output.
+			obuf, inbuf = inbuf, obuf
+		}
+
+		// Fill in the per-chunk header that comes before the body.
+		obuf[0] = chunkType
+		obuf[1] = uint8(chunkLen >> 0)
+		obuf[2] = uint8(chunkLen >> 8)
+		obuf[3] = uint8(chunkLen >> 16)
+		obuf[4] = uint8(checksum >> 0)
+		obuf[5] = uint8(checksum >> 8)
+		obuf[6] = uint8(checksum >> 16)
+		obuf[7] = uint8(checksum >> 24)
+
+		// Queue final output.
+		res.b = obuf
+		output <- res
+
+		// Put unused buffer back in pool.
+		w.buffers.Put(inbuf)
+	}()
+	return nil
+}
+
+func (w *Writer) writeSync(p []byte) (nRet int, errRet error) {
+	if err := w.err(nil); err != nil {
+		return 0, err
+	}
+	if !w.wroteStreamHeader {
+		w.wroteStreamHeader = true
+		var n int
+		var err error
+		if w.snappy {
+			n, err = w.writer.Write([]byte(magicChunkSnappy))
+		} else {
+			n, err = w.writer.Write([]byte(magicChunk))
+		}
+		if err != nil {
+			return 0, w.err(err)
+		}
+		if n != len(magicChunk) {
+			return 0, w.err(io.ErrShortWrite)
+		}
+		w.written += int64(n)
+	}
+
+	for len(p) > 0 {
+		var uncompressed []byte
+		if len(p) > w.blockSize {
+			uncompressed, p = p[:w.blockSize], p[w.blockSize:]
+		} else {
+			uncompressed, p = p, nil
+		}
+
+		obuf := w.buffers.Get().([]byte)[:w.obufLen]
+		checksum := crc(uncompressed)
+
+		// Set to uncompressed.
+		chunkType := uint8(chunkTypeUncompressedData)
+		chunkLen := 4 + len(uncompressed)
+
+		// Attempt compressing.
+		n := binary.PutUvarint(obuf[obufHeaderLen:], uint64(len(uncompressed)))
+		n2 := w.encodeBlock(obuf[obufHeaderLen+n:], uncompressed)
+
+		if n2 > 0 {
+			chunkType = uint8(chunkTypeCompressedData)
+			chunkLen = 4 + n + n2
+			obuf = obuf[:obufHeaderLen+n+n2]
+		} else {
+			obuf = obuf[:8]
+		}
+
+		// Fill in the per-chunk header that comes before the body.
+		obuf[0] = chunkType
+		obuf[1] = uint8(chunkLen >> 0)
+		obuf[2] = uint8(chunkLen >> 8)
+		obuf[3] = uint8(chunkLen >> 16)
+		obuf[4] = uint8(checksum >> 0)
+		obuf[5] = uint8(checksum >> 8)
+		obuf[6] = uint8(checksum >> 16)
+		obuf[7] = uint8(checksum >> 24)
+
+		n, err := w.writer.Write(obuf)
+		if err != nil {
+			return 0, w.err(err)
+		}
+		if n != len(obuf) {
+			return 0, w.err(io.ErrShortWrite)
+		}
+		w.err(w.index.add(w.written, w.uncompWritten))
+		w.written += int64(n)
+		w.uncompWritten += int64(len(uncompressed))
+
+		if chunkType == chunkTypeUncompressedData {
+			// Write uncompressed data.
+			n, err := w.writer.Write(uncompressed)
+			if err != nil {
+				return 0, w.err(err)
+			}
+			if n != len(uncompressed) {
+				return 0, w.err(io.ErrShortWrite)
+			}
+			w.written += int64(n)
+		}
+		w.buffers.Put(obuf)
+		// Queue final output.
+		nRet += len(uncompressed)
+	}
+	return nRet, nil
+}
+
+// Flush flushes the Writer to its underlying io.Writer.
+// This does not apply padding.
+func (w *Writer) Flush() error {
+	if err := w.err(nil); err != nil {
+		return err
+	}
+
+	// Queue any data still in input buffer.
+	if len(w.ibuf) != 0 {
+		if !w.wroteStreamHeader {
+			_, err := w.writeSync(w.ibuf)
+			w.ibuf = w.ibuf[:0]
+			return w.err(err)
+		} else {
+			_, err := w.write(w.ibuf)
+			w.ibuf = w.ibuf[:0]
+			err = w.err(err)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	if w.output == nil {
+		return w.err(nil)
+	}
+
+	// Send empty buffer
+	res := make(chan result)
+	w.output <- res
+	// Block until this has been picked up.
+	res <- result{b: nil, startOffset: w.uncompWritten}
+	// When it is closed, we have flushed.
+	<-res
+	return w.err(nil)
+}
+
+// Close calls Flush and then closes the Writer.
+// Calling Close multiple times is ok,
+// but calling CloseIndex after this will make it not return the index.
+func (w *Writer) Close() error {
+	_, err := w.closeIndex(w.appendIndex)
+	return err
+}
+
+// CloseIndex calls Close and returns an index on first call.
+// This is not required if you are only adding index to a stream.
+func (w *Writer) CloseIndex() ([]byte, error) {
+	return w.closeIndex(true)
+}
+
+func (w *Writer) closeIndex(idx bool) ([]byte, error) {
+	err := w.Flush()
+	if w.output != nil {
+		close(w.output)
+		w.writerWg.Wait()
+		w.output = nil
+	}
+
+	var index []byte
+	if w.err(nil) == nil && w.writer != nil {
+		// Create index.
+		if idx {
+			compSize := int64(-1)
+			if w.pad <= 1 {
+				compSize = w.written
+			}
+			index = w.index.appendTo(w.ibuf[:0], w.uncompWritten, compSize)
+			// Count as written for padding.
+			if w.appendIndex {
+				w.written += int64(len(index))
+			}
+		}
+
+		if w.pad > 1 {
+			tmp := w.ibuf[:0]
+			if len(index) > 0 {
+				// Allocate another buffer.
+				tmp = w.buffers.Get().([]byte)[:0]
+				defer w.buffers.Put(tmp)
+			}
+			add := calcSkippableFrame(w.written, int64(w.pad))
+			frame, err := skippableFrame(tmp, add, w.randSrc)
+			if err = w.err(err); err != nil {
+				return nil, err
+			}
+			n, err2 := w.writer.Write(frame)
+			if err2 == nil && n != len(frame) {
+				err2 = io.ErrShortWrite
+			}
+			_ = w.err(err2)
+		}
+		if len(index) > 0 && w.appendIndex {
+			n, err2 := w.writer.Write(index)
+			if err2 == nil && n != len(index) {
+				err2 = io.ErrShortWrite
+			}
+			_ = w.err(err2)
+		}
+	}
+	err = w.err(errClosed)
+	if err == errClosed {
+		return index, nil
+	}
+	return nil, err
+}
+
+// calcSkippableFrame will return a total size to be added for written
+// to be divisible by multiple.
+// The value will always be > skippableFrameHeader.
+// The function will panic if written < 0 or wantMultiple <= 0.
+func calcSkippableFrame(written, wantMultiple int64) int {
+	if wantMultiple <= 0 {
+		panic("wantMultiple <= 0")
+	}
+	if written < 0 {
+		panic("written < 0")
+	}
+	leftOver := written % wantMultiple
+	if leftOver == 0 {
+		return 0
+	}
+	toAdd := wantMultiple - leftOver
+	for toAdd < skippableFrameHeader {
+		toAdd += wantMultiple
+	}
+	return int(toAdd)
+}
+
+// skippableFrame will add a skippable frame with a total size of bytes.
+// total should be >= skippableFrameHeader and < maxBlockSize + skippableFrameHeader
+func skippableFrame(dst []byte, total int, r io.Reader) ([]byte, error) {
+	if total == 0 {
+		return dst, nil
+	}
+	if total < skippableFrameHeader {
+		return dst, fmt.Errorf("s2: requested skippable frame (%d) < 4", total)
+	}
+	if int64(total) >= maxBlockSize+skippableFrameHeader {
+		return dst, fmt.Errorf("s2: requested skippable frame (%d) >= max 1<<24", total)
+	}
+	// Chunk type 0xfe "Section 4.4 Padding (chunk type 0xfe)"
+	dst = append(dst, chunkTypePadding)
+	f := uint32(total - skippableFrameHeader)
+	// Add chunk length.
+	dst = append(dst, uint8(f), uint8(f>>8), uint8(f>>16))
+	// Add data
+	start := len(dst)
+	dst = append(dst, make([]byte, f)...)
+	_, err := io.ReadFull(r, dst[start:])
+	return dst, err
+}
+
+var errClosed = errors.New("s2: Writer is closed")
+
+// WriterOption is an option for creating a encoder.
+type WriterOption func(*Writer) error
+
+// WriterConcurrency will set the concurrency,
+// meaning the maximum number of decoders to run concurrently.
+// The value supplied must be at least 1.
+// By default this will be set to GOMAXPROCS.
+func WriterConcurrency(n int) WriterOption {
+	return func(w *Writer) error {
+		if n <= 0 {
+			return errors.New("concurrency must be at least 1")
+		}
+		w.concurrency = n
+		return nil
+	}
+}
+
+// WriterAddIndex will append an index to the end of a stream
+// when it is closed.
+func WriterAddIndex() WriterOption {
+	return func(w *Writer) error {
+		w.appendIndex = true
+		return nil
+	}
+}
+
+// WriterBetterCompression will enable better compression.
+// EncodeBetter compresses better than Encode but typically with a
+// 10-40% speed decrease on both compression and decompression.
+func WriterBetterCompression() WriterOption {
+	return func(w *Writer) error {
+		w.level = levelBetter
+		return nil
+	}
+}
+
+// WriterBestCompression will enable better compression.
+// EncodeBetter compresses better than Encode but typically with a
+// big speed decrease on compression.
+func WriterBestCompression() WriterOption {
+	return func(w *Writer) error {
+		w.level = levelBest
+		return nil
+	}
+}
+
+// WriterUncompressed will bypass compression.
+// The stream will be written as uncompressed blocks only.
+// If concurrency is > 1 CRC and output will still be done async.
+func WriterUncompressed() WriterOption {
+	return func(w *Writer) error {
+		w.level = levelUncompressed
+		return nil
+	}
+}
+
+// WriterBlockSize allows to override the default block size.
+// Blocks will be this size or smaller.
+// Minimum size is 4KB and and maximum size is 4MB.
+//
+// Bigger blocks may give bigger throughput on systems with many cores,
+// and will increase compression slightly, but it will limit the possible
+// concurrency for smaller payloads for both encoding and decoding.
+// Default block size is 1MB.
+//
+// When writing Snappy compatible output using WriterSnappyCompat,
+// the maximum block size is 64KB.
+func WriterBlockSize(n int) WriterOption {
+	return func(w *Writer) error {
+		if w.snappy && n > maxSnappyBlockSize || n < minBlockSize {
+			return errors.New("s2: block size too large. Must be <= 64K and >=4KB on for snappy compatible output")
+		}
+		if n > maxBlockSize || n < minBlockSize {
+			return errors.New("s2: block size too large. Must be <= 4MB and >=4KB")
+		}
+		w.blockSize = n
+		return nil
+	}
+}
+
+// WriterPadding will add padding to all output so the size will be a multiple of n.
+// This can be used to obfuscate the exact output size or make blocks of a certain size.
+// The contents will be a skippable frame, so it will be invisible by the decoder.
+// n must be > 0 and <= 4MB.
+// The padded area will be filled with data from crypto/rand.Reader.
+// The padding will be applied whenever Close is called on the writer.
+func WriterPadding(n int) WriterOption {
+	return func(w *Writer) error {
+		if n <= 0 {
+			return fmt.Errorf("s2: padding must be at least 1")
+		}
+		// No need to waste our time.
+		if n == 1 {
+			w.pad = 0
+		}
+		if n > maxBlockSize {
+			return fmt.Errorf("s2: padding must less than 4MB")
+		}
+		w.pad = n
+		return nil
+	}
+}
+
+// WriterPaddingSrc will get random data for padding from the supplied source.
+// By default crypto/rand is used.
+func WriterPaddingSrc(reader io.Reader) WriterOption {
+	return func(w *Writer) error {
+		w.randSrc = reader
+		return nil
+	}
+}
+
+// WriterSnappyCompat will write snappy compatible output.
+// The output can be decompressed using either snappy or s2.
+// If block size is more than 64KB it is set to that.
+func WriterSnappyCompat() WriterOption {
+	return func(w *Writer) error {
+		w.snappy = true
+		if w.blockSize > 64<<10 {
+			// We choose 8 bytes less than 64K, since that will make literal emits slightly more effective.
+			// And allows us to skip some size checks.
+			w.blockSize = (64 << 10) - 8
+		}
+		return nil
+	}
+}
+
+// WriterFlushOnWrite will compress blocks on each call to the Write function.
+//
+// This is quite inefficient as blocks size will depend on the write size.
+//
+// Use WriterConcurrency(1) to also make sure that output is flushed.
+// When Write calls return, otherwise they will be written when compression is done.
+func WriterFlushOnWrite() WriterOption {
+	return func(w *Writer) error {
+		w.flushOnWrite = true
+		return nil
+	}
+}
+
+// WriterCustomEncoder allows to override the encoder for blocks on the stream.
+// The function must compress 'src' into 'dst' and return the bytes used in dst as an integer.
+// Block size (initial varint) should not be added by the encoder.
+// Returning value 0 indicates the block could not be compressed.
+// Returning a negative value indicates that compression should be attempted.
+// The function should expect to be called concurrently.
+func WriterCustomEncoder(fn func(dst, src []byte) int) WriterOption {
+	return func(w *Writer) error {
+		w.customEnc = fn
+		return nil
+	}
+}