1 files changed, 267 insertions, 0 deletions
diff --git a/vendor/github.com/pierrec/lz4/writer.go b/vendor/github.com/pierrec/lz4/writer.go
new file mode 100644
index 0000000000..0120438025
--- /dev/null
+++ b/vendor/github.com/pierrec/lz4/writer.go
@@ -0,0 +1,267 @@
+package lz4
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+
+	"github.com/pierrec/lz4/internal/xxh32"
+)
+
+// Writer implements the LZ4 frame encoder.
+type Writer struct {
+	Header
+
+	buf       [19]byte      // magic number(4) + header(flags(2)+[Size(8)+DictID(4)]+checksum(1)) does not exceed 19 bytes
+	dst       io.Writer     // Destination.
+	checksum  xxh32.XXHZero // Frame checksum.
+	zdata     []byte        // Compressed data.
+	data      []byte        // Data to be compressed.
+	idx       int           // Index into data.
+	hashtable [winSize]int  // Hash table used in CompressBlock().
+}
+
+// NewWriter returns a new LZ4 frame encoder.
+// No access to the underlying io.Writer is performed.
+// The supplied Header is checked at the first Write.
+// It is ok to change it before the first Write but then not until a Reset() is performed.
+func NewWriter(dst io.Writer) *Writer {
+	return &Writer{dst: dst}
+}
+
+// writeHeader builds and writes the header (magic+header) to the underlying io.Writer.
+func (z *Writer) writeHeader() error {
+	// Default to 4Mb if BlockMaxSize is not set.
+	if z.Header.BlockMaxSize == 0 {
+		z.Header.BlockMaxSize = bsMapID[7]
+	}
+	// The only option that needs to be validated.
+	bSize := z.Header.BlockMaxSize
+	bSizeID, ok := bsMapValue[bSize]
+	if !ok {
+		return fmt.Errorf("lz4: invalid block max size: %d", bSize)
+	}
+	// Allocate the compressed/uncompressed buffers.
+	// The compressed buffer cannot exceed the uncompressed one.
+	if n := 2 * bSize; cap(z.zdata) < n {
+		z.zdata = make([]byte, n, n)
+	}
+	z.zdata = z.zdata[:bSize]
+	z.data = z.zdata[:cap(z.zdata)][bSize:]
+	z.idx = 0
+
+	// Size is optional.
+	buf := z.buf[:]
+
+	// Set the fixed size data: magic number, block max size and flags.
+	binary.LittleEndian.PutUint32(buf[0:], frameMagic)
+	flg := byte(Version << 6)
+	flg |= 1 << 5 // No block dependency.
+	if z.Header.BlockChecksum {
+		flg |= 1 << 4
+	}
+	if z.Header.Size > 0 {
+		flg |= 1 << 3
+	}
+	if !z.Header.NoChecksum {
+		flg |= 1 << 2
+	}
+	buf[4] = flg
+	buf[5] = bSizeID << 4
+
+	// Current buffer size: magic(4) + flags(1) + block max size (1).
+	n := 6
+	// Optional items.
+	if z.Header.Size > 0 {
+		binary.LittleEndian.PutUint64(buf[n:], z.Header.Size)
+		n += 8
+	}
+
+	// The header checksum includes the flags, block max size and optional Size.
+	buf[n] = byte(xxh32.ChecksumZero(buf[4:n]) >> 8 & 0xFF)
+	z.checksum.Reset()
+
+	// Header ready, write it out.
+	if _, err := z.dst.Write(buf[0 : n+1]); err != nil {
+		return err
+	}
+	z.Header.done = true
+	if debugFlag {
+		debug("wrote header %v", z.Header)
+	}
+
+	return nil
+}
+
+// Write compresses data from the supplied buffer into the underlying io.Writer.
+// Write does not return until the data has been written.
+func (z *Writer) Write(buf []byte) (int, error) {
+	if !z.Header.done {
+		if err := z.writeHeader(); err != nil {
+			return 0, err
+		}
+	}
+	if debugFlag {
+		debug("input buffer len=%d index=%d", len(buf), z.idx)
+	}
+
+	zn := len(z.data)
+	var n int
+	for len(buf) > 0 {
+		if z.idx == 0 && len(buf) >= zn {
+			// Avoid a copy as there is enough data for a block.
+			if err := z.compressBlock(buf[:zn]); err != nil {
+				return n, err
+			}
+			n += zn
+			buf = buf[zn:]
+			continue
+		}
+		// Accumulate the data to be compressed.
+		m := copy(z.data[z.idx:], buf)
+		n += m
+		z.idx += m
+		buf = buf[m:]
+		if debugFlag {
+			debug("%d bytes copied to buf, current index %d", n, z.idx)
+		}
+
+		if z.idx < len(z.data) {
+			// Buffer not filled.
+			if debugFlag {
+				debug("need more data for compression")
+			}
+			return n, nil
+		}
+
+		// Buffer full.
+		if err := z.compressBlock(z.data); err != nil {
+			return n, err
+		}
+		z.idx = 0
+	}
+
+	return n, nil
+}
+
+// compressBlock compresses a block.
+func (z *Writer) compressBlock(data []byte) error {
+	if !z.NoChecksum {
+		z.checksum.Write(data)
+	}
+
+	// The compressed block size cannot exceed the input's.
+	var zn int
+	var err error
+
+	if level := z.Header.CompressionLevel; level != 0 {
+		zn, err = CompressBlockHC(data, z.zdata, level)
+	} else {
+		zn, err = CompressBlock(data, z.zdata, z.hashtable[:])
+	}
+
+	var zdata []byte
+	var bLen uint32
+	if debugFlag {
+		debug("block compression %d => %d", len(data), zn)
+	}
+	if err == nil && zn > 0 && zn < len(data) {
+		// Compressible and compressed size smaller than uncompressed: ok!
+		bLen = uint32(zn)
+		zdata = z.zdata[:zn]
+	} else {
+		// Uncompressed block.
+		bLen = uint32(len(data)) | compressedBlockFlag
+		zdata = data
+	}
+	if debugFlag {
+		debug("block compression to be written len=%d data len=%d", bLen, len(zdata))
+	}
+
+	// Write the block.
+	if err := z.writeUint32(bLen); err != nil {
+		return err
+	}
+	if _, err := z.dst.Write(zdata); err != nil {
+		return err
+	}
+
+	if z.BlockChecksum {
+		checksum := xxh32.ChecksumZero(zdata)
+		if debugFlag {
+			debug("block checksum %x", checksum)
+		}
+		if err := z.writeUint32(checksum); err != nil {
+			return err
+		}
+	}
+	if debugFlag {
+		debug("current frame checksum %x", z.checksum.Sum32())
+	}
+
+	return nil
+}
+
+// Flush flushes any pending compressed data to the underlying writer.
+// Flush does not return until the data has been written.
+// If the underlying writer returns an error, Flush returns that error.
+func (z *Writer) Flush() error {
+	if debugFlag {
+		debug("flush with index %d", z.idx)
+	}
+	if z.idx == 0 {
+		return nil
+	}
+
+	return z.compressBlock(z.data[:z.idx])
+}
+
+// Close closes the Writer, flushing any unwritten data to the underlying io.Writer, but does not close the underlying io.Writer.
+func (z *Writer) Close() error {
+	if !z.Header.done {
+		if err := z.writeHeader(); err != nil {
+			return err
+		}
+	}
+
+	if err := z.Flush(); err != nil {
+		return err
+	}
+
+	if debugFlag {
+		debug("writing last empty block")
+	}
+	if err := z.writeUint32(0); err != nil {
+		return err
+	}
+	if !z.NoChecksum {
+		checksum := z.checksum.Sum32()
+		if debugFlag {
+			debug("stream checksum %x", checksum)
+		}
+		if err := z.writeUint32(checksum); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Reset clears the state of the Writer z such that it is equivalent to its
+// initial state from NewWriter, but instead writing to w.
+// No access to the underlying io.Writer is performed.
+func (z *Writer) Reset(w io.Writer) {
+	z.Header = Header{}
+	z.dst = w
+	z.checksum.Reset()
+	z.zdata = z.zdata[:0]
+	z.data = z.data[:0]
+	z.idx = 0
+}
+
+// writeUint32 writes a uint32 to the underlying writer.
+func (z *Writer) writeUint32(x uint32) error {
+	buf := z.buf[:4]
+	binary.LittleEndian.PutUint32(buf, x)
+	_, err := z.dst.Write(buf)
+	return err
+}