Update to last common bleve (#3986)

vendor/github.com/glycerine/go-unsnap-stream/unsnap.go

@@ -0,0 +1,513 @@
+package unsnap
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+
+	"hash/crc32"
+
+	snappy "github.com/golang/snappy"
+	// The C library can be used, but this makes the binary dependent
+	// lots of extraneous c-libraries; it is no longer stand-alone. Yuck.
+	//
+	// Therefore we comment out the "dgryski/go-csnappy" path and use the
+	// "github.com/golang/snappy/snappy" above instead. If you are
+	// performance limited and can deal with distributing more libraries,
+	// then this is easy to swap.
+	//
+	// If you swap, note that some of the tests won't pass
+	// because snappy-go produces slightly different (but still
+	// conformant) encodings on some data. Here are bindings
+	// to the C-snappy:
+	// snappy "github.com/dgryski/go-csnappy"
+)
+
+// SnappyFile: create a drop-in-replacement/wrapper for an *os.File that handles doing the unsnappification online as more is read from it
+
+type SnappyFile struct {
+	Fname string
+
+	Reader io.Reader
+	Writer io.Writer
+
+	// allow clients to substitute us for an os.File and just switch
+	// off compression if they don't want it.
+	SnappyEncodeDecodeOff bool // if true, we bypass straight to Filep
+
+	EncBuf FixedSizeRingBuf // holds any extra that isn't yet returned, encoded
+	DecBuf FixedSizeRingBuf // holds any extra that isn't yet returned, decoded
+
+	// for writing to stream-framed snappy
+	HeaderChunkWritten bool
+
+	// Sanity check: we can only read, or only write, to one SnappyFile.
+	// EncBuf and DecBuf are used differently in each mode. Verify
+	// that we are consistent with this flag.
+	Writing bool
+}
+
+var total int
+
+// for debugging, show state of buffers
+func (f *SnappyFile) Dump() {
+	fmt.Printf("EncBuf has length %d and contents:\n%s\n", len(f.EncBuf.Bytes()), string(f.EncBuf.Bytes()))
+	fmt.Printf("DecBuf has length %d and contents:\n%s\n", len(f.DecBuf.Bytes()), string(f.DecBuf.Bytes()))
+}
+
+func (f *SnappyFile) Read(p []byte) (n int, err error) {
+
+	if f.SnappyEncodeDecodeOff {
+		return f.Reader.Read(p)
+	}
+
+	if f.Writing {
+		panic("Reading on a write-only SnappyFile")
+	}
+
+	// before we unencrypt more, try to drain the DecBuf first
+	n, _ = f.DecBuf.Read(p)
+	if n > 0 {
+		total += n
+		return n, nil
+	}
+
+	//nEncRead, nDecAdded, err := UnsnapOneFrame(f.Filep, &f.EncBuf, &f.DecBuf, f.Fname)
+	_, _, err = UnsnapOneFrame(f.Reader, &f.EncBuf, &f.DecBuf, f.Fname)
+	if err != nil && err != io.EOF {
+		panic(err)
+	}
+
+	n, _ = f.DecBuf.Read(p)
+
+	if n > 0 {
+		total += n
+		return n, nil
+	}
+	if f.DecBuf.Readable == 0 {
+		if f.DecBuf.Readable == 0 && f.EncBuf.Readable == 0 {
+			// only now (when EncBuf is empty) can we give io.EOF.
+			// Any earlier, and we leave stuff un-decoded!
+			return 0, io.EOF
+		}
+	}
+	return 0, nil
+}
+
+func Open(name string) (file *SnappyFile, err error) {
+	fp, err := os.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	// encoding in snappy can apparently go beyond the original size, so
+	// we make our buffers big enough, 2*max snappy chunk => 2 * CHUNK_MAX(65536)
+
+	snap := NewReader(fp)
+	snap.Fname = name
+	return snap, nil
+}
+
+func NewReader(r io.Reader) *SnappyFile {
+	return &SnappyFile{
+		Reader:  r,
+		EncBuf:  *NewFixedSizeRingBuf(CHUNK_MAX * 2), // buffer of snappy encoded bytes
+		DecBuf:  *NewFixedSizeRingBuf(CHUNK_MAX * 2), // buffer of snapppy decoded bytes
+		Writing: false,
+	}
+}
+
+func NewWriter(w io.Writer) *SnappyFile {
+	return &SnappyFile{
+		Writer:  w,
+		EncBuf:  *NewFixedSizeRingBuf(65536),     // on writing: temp for testing compression
+		DecBuf:  *NewFixedSizeRingBuf(65536 * 2), // on writing: final buffer of snappy framed and encoded bytes
+		Writing: true,
+	}
+}
+
+func Create(name string) (file *SnappyFile, err error) {
+	fp, err := os.Create(name)
+	if err != nil {
+		return nil, err
+	}
+	snap := NewWriter(fp)
+	snap.Fname = name
+	return snap, nil
+}
+
+func (f *SnappyFile) Close() error {
+	if f.Writing {
+		wc, ok := f.Writer.(io.WriteCloser)
+		if ok {
+			return wc.Close()
+		}
+		return nil
+	}
+	rc, ok := f.Reader.(io.ReadCloser)
+	if ok {
+		return rc.Close()
+	}
+	return nil
+}
+
+func (f *SnappyFile) Sync() error {
+	file, ok := f.Writer.(*os.File)
+	if ok {
+		return file.Sync()
+	}
+	return nil
+}
+
+// for an increment of a frame at a time:
+// read from r into encBuf (encBuf is still encoded, thus the name), and write unsnappified frames into outDecodedBuf
+//  the returned n: number of bytes read from the encrypted encBuf
+func UnsnapOneFrame(r io.Reader, encBuf *FixedSizeRingBuf, outDecodedBuf *FixedSizeRingBuf, fname string) (nEnc int64, nDec int64, err error) {
+	//	b, err := ioutil.ReadAll(r)
+	//	if err != nil {
+	//		panic(err)
+	//	}
+
+	nEnc = 0
+	nDec = 0
+
+	// read up to 65536 bytes from r into encBuf, at least a snappy frame
+	nread, err := io.CopyN(encBuf, r, 65536) // returns nwrotebytes, err
+	nEnc += nread
+	if err != nil {
+		if err == io.EOF {
+			if nread == 0 {
+				if encBuf.Readable == 0 {
+					return nEnc, nDec, io.EOF
+				}
+				// else we have bytes in encBuf, so decode them!
+				err = nil
+			} else {
+				// continue below, processing the nread bytes
+				err = nil
+			}
+		} else {
+			panic(err)
+		}
+	}
+
+	// flag for printing chunk size alignment messages
+	verbose := false
+
+	const snappyStreamHeaderSz = 10
+	const headerSz = 4
+	const crc32Sz = 4
+	// the magic 18 bytes accounts for the snappy streaming header and the first chunks size and checksum
+	// http://code.google.com/p/snappy/source/browse/trunk/framing_format.txt
+
+	chunk := (*encBuf).Bytes()
+
+	// however we exit, advance as
+	//	defer func() { (*encBuf).Next(N) }()
+
+	// 65536 is the max size of a snappy framed chunk. See
+	// http://code.google.com/p/snappy/source/browse/trunk/framing_format.txt:91
+	// buf := make([]byte, 65536)
+
+	//	fmt.Printf("read from file, b is len:%d with value: %#v\n", len(b), b)
+	//	fmt.Printf("read from file, bcut is len:%d with value: %#v\n", len(bcut), bcut)
+
+	//fmt.Printf("raw bytes of chunksz are: %v\n", b[11:14])
+
+	fourbytes := make([]byte, 4)
+	chunkCount := 0
+
+	for nDec < 65536 {
+		if len(chunk) == 0 {
+			break
+		}
+		chunkCount++
+		fourbytes[3] = 0
+		copy(fourbytes, chunk[1:4])
+		chunksz := binary.LittleEndian.Uint32(fourbytes)
+		chunk_type := chunk[0]
+
+		switch true {
+		case chunk_type == 0xff:
+			{ // stream identifier
+
+				streamHeader := chunk[:snappyStreamHeaderSz]
+				if 0 != bytes.Compare(streamHeader, []byte{0xff, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61, 0x50, 0x70, 0x59}) {
+					panic("file had chunk starting with 0xff but then no magic snappy streaming protocol bytes, aborting.")
+				} else {
+					//fmt.Printf("got streaming snappy magic header just fine.\n")
+				}
+				chunk = chunk[snappyStreamHeaderSz:]
+				(*encBuf).Advance(snappyStreamHeaderSz)
+				nEnc += snappyStreamHeaderSz
+				continue
+			}
+		case chunk_type == 0x00:
+			{ // compressed data
+				if verbose {
+					fmt.Fprintf(os.Stderr, "chunksz is %d  while  total bytes avail are: %d\n", int(chunksz), len(chunk)-4)
+				}
+
+				crc := binary.LittleEndian.Uint32(chunk[headerSz:(headerSz + crc32Sz)])
+				section := chunk[(headerSz + crc32Sz):(headerSz + chunksz)]
+
+				dec, ok := snappy.Decode(nil, section)
+				if ok != nil {
+					// we've probably truncated a snappy frame at this point
+					// ok=snappy: corrupt input
+					// len(dec) == 0
+					//
+					panic(fmt.Sprintf("could not decode snappy stream: '%s' and len dec=%d and ok=%v\n", fname, len(dec), ok))
+
+					// get back to caller with what we've got so far
+					return nEnc, nDec, nil
+				}
+				//	fmt.Printf("ok, b is %#v , %#v\n", ok, dec)
+
+				// spit out decoded text
+				// n, err := w.Write(dec)
+				//fmt.Printf("len(dec) = %d,   outDecodedBuf.Readable=%d\n", len(dec), outDecodedBuf.Readable)
+				bnb := bytes.NewBuffer(dec)
+				n, err := io.Copy(outDecodedBuf, bnb)
+				if err != nil {
+					//fmt.Printf("got n=%d, err= %s ; when trying to io.Copy(outDecodedBuf: N=%d, Readable=%d)\n", n, err, outDecodedBuf.N, outDecodedBuf.Readable)
+					panic(err)
+				}
+				if n != int64(len(dec)) {
+					panic("could not write all bytes to outDecodedBuf")
+				}
+				nDec += n
+
+				// verify the crc32 rotated checksum
+				m32 := masked_crc32c(dec)
+				if m32 != crc {
+					panic(fmt.Sprintf("crc32 masked failiure. expected: %v but got: %v", crc, m32))
+				} else {
+					//fmt.Printf("\nchecksums match: %v == %v\n", crc, m32)
+				}
+
+				// move to next header
+				inc := (headerSz + int(chunksz))
+				chunk = chunk[inc:]
+				(*encBuf).Advance(inc)
+				nEnc += int64(inc)
+				continue
+			}
+		case chunk_type == 0x01:
+			{ // uncompressed data
+
+				//n, err := w.Write(chunk[(headerSz+crc32Sz):(headerSz + int(chunksz))])
+				n, err := io.Copy(outDecodedBuf, bytes.NewBuffer(chunk[(headerSz+crc32Sz):(headerSz+int(chunksz))]))
+				if verbose {
+					//fmt.Printf("debug: n=%d  err=%v  chunksz=%d  outDecodedBuf='%v'\n", n, err, chunksz, outDecodedBuf)
+				}
+				if err != nil {
+					panic(err)
+				}
+				if n != int64(chunksz-crc32Sz) {
+					panic("could not write all bytes to stdout")
+				}
+				nDec += n
+
+				inc := (headerSz + int(chunksz))
+				chunk = chunk[inc:]
+				(*encBuf).Advance(inc)
+				nEnc += int64(inc)
+				continue
+			}
+		case chunk_type == 0xfe:
+			fallthrough // padding, just skip it
+		case chunk_type >= 0x80 && chunk_type <= 0xfd:
+			{ //  Reserved skippable chunks
+				//fmt.Printf("\nin reserved skippable chunks, at nEnc=%v\n", nEnc)
+				inc := (headerSz + int(chunksz))
+				chunk = chunk[inc:]
+				nEnc += int64(inc)
+				(*encBuf).Advance(inc)
+				continue
+			}
+
+		default:
+			panic(fmt.Sprintf("unrecognized/unsupported chunk type %#v", chunk_type))
+		}
+
+	} // end for{}
+
+	return nEnc, nDec, err
+	//return int64(N), nil
+}
+
+// for whole file at once:
+//
+// receive on stdin a stream of bytes in the snappy-streaming framed
+//  format, defined here: http://code.google.com/p/snappy/source/browse/trunk/framing_format.txt
+// Grab each frame, run it through the snappy decoder, and spit out
+//  each frame all joined back-to-back on stdout.
+//
+func Unsnappy(r io.Reader, w io.Writer) (err error) {
+	b, err := ioutil.ReadAll(r)
+	if err != nil {
+		panic(err)
+	}
+
+	// flag for printing chunk size alignment messages
+	verbose := false
+
+	const snappyStreamHeaderSz = 10
+	const headerSz = 4
+	const crc32Sz = 4
+	// the magic 18 bytes accounts for the snappy streaming header and the first chunks size and checksum
+	// http://code.google.com/p/snappy/source/browse/trunk/framing_format.txt
+
+	chunk := b[:]
+
+	// 65536 is the max size of a snappy framed chunk. See
+	// http://code.google.com/p/snappy/source/browse/trunk/framing_format.txt:91
+	//buf := make([]byte, 65536)
+
+	//	fmt.Printf("read from file, b is len:%d with value: %#v\n", len(b), b)
+	//	fmt.Printf("read from file, bcut is len:%d with value: %#v\n", len(bcut), bcut)
+
+	//fmt.Printf("raw bytes of chunksz are: %v\n", b[11:14])
+
+	fourbytes := make([]byte, 4)
+	chunkCount := 0
+
+	for {
+		if len(chunk) == 0 {
+			break
+		}
+		chunkCount++
+		fourbytes[3] = 0
+		copy(fourbytes, chunk[1:4])
+		chunksz := binary.LittleEndian.Uint32(fourbytes)
+		chunk_type := chunk[0]
+
+		switch true {
+		case chunk_type == 0xff:
+			{ // stream identifier
+
+				streamHeader := chunk[:snappyStreamHeaderSz]
+				if 0 != bytes.Compare(streamHeader, []byte{0xff, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61, 0x50, 0x70, 0x59}) {
+					panic("file had chunk starting with 0xff but then no magic snappy streaming protocol bytes, aborting.")
+				} else {
+					//fmt.Printf("got streaming snappy magic header just fine.\n")
+				}
+				chunk = chunk[snappyStreamHeaderSz:]
+				continue
+			}
+		case chunk_type == 0x00:
+			{ // compressed data
+				if verbose {
+					fmt.Fprintf(os.Stderr, "chunksz is %d  while  total bytes avail are: %d\n", int(chunksz), len(chunk)-4)
+				}
+
+				//crc := binary.LittleEndian.Uint32(chunk[headerSz:(headerSz + crc32Sz)])
+				section := chunk[(headerSz + crc32Sz):(headerSz + chunksz)]
+
+				dec, ok := snappy.Decode(nil, section)
+				if ok != nil {
+					panic("could not decode snappy stream")
+				}
+				//	fmt.Printf("ok, b is %#v , %#v\n", ok, dec)
+
+				// spit out decoded text
+				n, err := w.Write(dec)
+				if err != nil {
+					panic(err)
+				}
+				if n != len(dec) {
+					panic("could not write all bytes to stdout")
+				}
+
+				// TODO: verify the crc32 rotated checksum?
+
+				// move to next header
+				chunk = chunk[(headerSz + int(chunksz)):]
+				continue
+			}
+		case chunk_type == 0x01:
+			{ // uncompressed data
+
+				//crc := binary.LittleEndian.Uint32(chunk[headerSz:(headerSz + crc32Sz)])
+				section := chunk[(headerSz + crc32Sz):(headerSz + chunksz)]
+
+				n, err := w.Write(section)
+				if err != nil {
+					panic(err)
+				}
+				if n != int(chunksz-crc32Sz) {
+					panic("could not write all bytes to stdout")
+				}
+
+				chunk = chunk[(headerSz + int(chunksz)):]
+				continue
+			}
+		case chunk_type == 0xfe:
+			fallthrough // padding, just skip it
+		case chunk_type >= 0x80 && chunk_type <= 0xfd:
+			{ //  Reserved skippable chunks
+				chunk = chunk[(headerSz + int(chunksz)):]
+				continue
+			}
+
+		default:
+			panic(fmt.Sprintf("unrecognized/unsupported chunk type %#v", chunk_type))
+		}
+
+	} // end for{}
+
+	return nil
+}
+
+// 0xff 0x06 0x00 0x00 sNaPpY
+var SnappyStreamHeaderMagic = []byte{0xff, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61, 0x50, 0x70, 0x59}
+
+const CHUNK_MAX = 65536
+const _STREAM_TO_STREAM_BLOCK_SIZE = CHUNK_MAX
+const _STREAM_IDENTIFIER = `sNaPpY`
+const _COMPRESSED_CHUNK = 0x00
+const _UNCOMPRESSED_CHUNK = 0x01
+const _IDENTIFIER_CHUNK = 0xff
+const _RESERVED_UNSKIPPABLE0 = 0x02 // chunk ranges are [inclusive, exclusive)
+const _RESERVED_UNSKIPPABLE1 = 0x80
+const _RESERVED_SKIPPABLE0 = 0x80
+const _RESERVED_SKIPPABLE1 = 0xff
+
+// the minimum percent of bytes compression must save to be enabled in automatic
+// mode
+const _COMPRESSION_THRESHOLD = .125
+
+var crctab *crc32.Table
+
+func init() {
+	crctab = crc32.MakeTable(crc32.Castagnoli) // this is correct table, matches the crc32c.c code used by python
+}
+
+func masked_crc32c(data []byte) uint32 {
+
+	// see the framing format specification, http://code.google.com/p/snappy/source/browse/trunk/framing_format.txt
+	var crc uint32 = crc32.Checksum(data, crctab)
+	return (uint32((crc>>15)|(crc<<17)) + 0xa282ead8)
+}
+
+func ReadSnappyStreamCompressedFile(filename string) ([]byte, error) {
+
+	snappyFile, err := Open(filename)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	var bb bytes.Buffer
+	_, err = bb.ReadFrom(snappyFile)
+	if err == io.EOF {
+		err = nil
+	}
+	if err != nil {
+		panic(err)
+	}
+
+	return bb.Bytes(), err
+}