vendor containers/storage with https://github.com/containers/storage/pull/1165

Signed-off-by: Dan Čermák <dcermak@suse.com>

9 files changed, 98 insertions, 71 deletions

diff --git a/vendor/github.com/klauspost/compress/zstd/README.md b/vendor/github.com/klauspost/compress/zstd/README.md
index c876c591a..e3445ac19 100644
--- a/vendor/github.com/klauspost/compress/zstd/README.md
+++ b/vendor/github.com/klauspost/compress/zstd/README.md
@@ -153,10 +153,10 @@ http://sun.aei.polsl.pl/~sdeor/corpus/silesia.zip
 
 This package:
 file    out     level   insize      outsize     millis  mb/s
-silesia.tar zskp    1   211947520   73101992    643     313.87
-silesia.tar zskp    2   211947520   67504318    969     208.38
-silesia.tar zskp    3   211947520   64595893    2007    100.68
-silesia.tar zskp    4   211947520   60995370    8825    22.90
+silesia.tar zskp    1   211947520   73821326    634     318.47
+silesia.tar zskp    2   211947520   67655404    1508    133.96
+silesia.tar zskp    3   211947520   64746933    3000    67.37
+silesia.tar zskp    4   211947520   60073508    16926   11.94
 
 cgo zstd:
 silesia.tar zstd    1   211947520   73605392    543     371.56
@@ -165,94 +165,94 @@ silesia.tar zstd    6   211947520   62916450    1913    105.66
 silesia.tar zstd    9   211947520   60212393    5063    39.92
 
 gzip, stdlib/this package:
-silesia.tar gzstd   1   211947520   80007735    1654    122.21
-silesia.tar gzkp    1   211947520   80136201    1152    175.45
+silesia.tar gzstd   1   211947520   80007735    1498    134.87
+silesia.tar gzkp    1   211947520   80088272    1009    200.31
 
 GOB stream of binary data. Highly compressible.
 https://files.klauspost.com/compress/gob-stream.7z
 
 file        out     level   insize  outsize     millis  mb/s
-gob-stream  zskp    1   1911399616  235022249   3088    590.30
-gob-stream  zskp    2   1911399616  205669791   3786    481.34
-gob-stream  zskp    3   1911399616  175034659   9636    189.17
-gob-stream  zskp    4   1911399616  165609838   50369   36.19
+gob-stream  zskp    1   1911399616  233948096   3230    564.34
+gob-stream  zskp    2   1911399616  203997694   4997    364.73
+gob-stream  zskp    3   1911399616  173526523   13435   135.68
+gob-stream  zskp    4   1911399616  162195235   47559   38.33
 
 gob-stream  zstd    1   1911399616  249810424   2637    691.26
 gob-stream  zstd    3   1911399616  208192146   3490    522.31
 gob-stream  zstd    6   1911399616  193632038   6687    272.56
 gob-stream  zstd    9   1911399616  177620386   16175   112.70
 
-gob-stream  gzstd   1   1911399616  357382641   10251   177.82
-gob-stream  gzkp    1   1911399616  359753026   5438    335.20
+gob-stream  gzstd   1   1911399616  357382013   9046    201.49
+gob-stream  gzkp    1   1911399616  359136669   4885    373.08
 
 The test data for the Large Text Compression Benchmark is the first
 10^9 bytes of the English Wikipedia dump on Mar. 3, 2006.
 http://mattmahoney.net/dc/textdata.html
 
 file    out level   insize      outsize     millis  mb/s
-enwik9  zskp    1   1000000000  343848582   3609    264.18
-enwik9  zskp    2   1000000000  317276632   5746    165.97
-enwik9  zskp    3   1000000000  292243069   12162   78.41
-enwik9  zskp    4   1000000000  262183768   82837   11.51
+enwik9  zskp    1   1000000000  343833605   3687    258.64
+enwik9  zskp    2   1000000000  317001237   7672    124.29
+enwik9  zskp    3   1000000000  291915823   15923   59.89
+enwik9  zskp    4   1000000000  261710291   77697   12.27
 
 enwik9  zstd    1   1000000000  358072021   3110    306.65
 enwik9  zstd    3   1000000000  313734672   4784    199.35
 enwik9  zstd    6   1000000000  295138875   10290   92.68
 enwik9  zstd    9   1000000000  278348700   28549   33.40
 
-enwik9  gzstd   1   1000000000  382578136   9604    99.30
-enwik9  gzkp    1   1000000000  383825945   6544    145.73
+enwik9  gzstd   1   1000000000  382578136   8608    110.78
+enwik9  gzkp    1   1000000000  382781160   5628    169.45
 
 Highly compressible JSON file.
 https://files.klauspost.com/compress/github-june-2days-2019.json.zst
 
 file                        out level   insize      outsize     millis  mb/s
-github-june-2days-2019.json zskp    1   6273951764  699045015   10620   563.40
-github-june-2days-2019.json zskp    2   6273951764  617881763   11687   511.96
-github-june-2days-2019.json zskp    3   6273951764  524340691   34043   175.75
-github-june-2days-2019.json zskp    4   6273951764  470320075   170190  35.16
+github-june-2days-2019.json zskp    1   6273951764  697439532   9789    611.17
+github-june-2days-2019.json zskp    2   6273951764  610876538   18553   322.49
+github-june-2days-2019.json zskp    3   6273951764  517662858   44186   135.41
+github-june-2days-2019.json zskp    4   6273951764  464617114   165373  36.18
 
 github-june-2days-2019.json zstd    1   6273951764  766284037   8450    708.00
 github-june-2days-2019.json zstd    3   6273951764  661889476   10927   547.57
 github-june-2days-2019.json zstd    6   6273951764  642756859   22996   260.18
 github-june-2days-2019.json zstd    9   6273951764  601974523   52413   114.16
 
-github-june-2days-2019.json gzstd   1   6273951764  1164400847  29948   199.79
-github-june-2days-2019.json gzkp    1   6273951764  1125417694  21788   274.61
+github-june-2days-2019.json gzstd   1   6273951764  1164397768  26793   223.32
+github-june-2days-2019.json gzkp    1   6273951764  1120631856  17693   338.16
 
 VM Image, Linux mint with a few installed applications:
 https://files.klauspost.com/compress/rawstudio-mint14.7z
 
 file                    out level   insize      outsize     millis  mb/s
-rawstudio-mint14.tar    zskp    1   8558382592  3667489370  20210   403.84
-rawstudio-mint14.tar    zskp    2   8558382592  3364592300  31873   256.07
-rawstudio-mint14.tar    zskp    3   8558382592  3158085214  77675   105.08
-rawstudio-mint14.tar    zskp    4   8558382592  2965110639  857750  9.52
+rawstudio-mint14.tar    zskp    1   8558382592  3718400221  18206   448.29
+rawstudio-mint14.tar    zskp    2   8558382592  3326118337  37074   220.15
+rawstudio-mint14.tar    zskp    3   8558382592  3163842361  87306   93.49
+rawstudio-mint14.tar    zskp    4   8558382592  2970480650  783862  10.41
 
 rawstudio-mint14.tar    zstd    1   8558382592  3609250104  17136   476.27
 rawstudio-mint14.tar    zstd    3   8558382592  3341679997  29262   278.92
 rawstudio-mint14.tar    zstd    6   8558382592  3235846406  77904   104.77
 rawstudio-mint14.tar    zstd    9   8558382592  3160778861  140946  57.91
 
-rawstudio-mint14.tar    gzstd   1   8558382592  3926257486  57722   141.40
-rawstudio-mint14.tar    gzkp    1   8558382592  3962605659  45113   180.92
+rawstudio-mint14.tar    gzstd   1   8558382592  3926234992  51345   158.96
+rawstudio-mint14.tar    gzkp    1   8558382592  3960117298  36722   222.26
 
 CSV data:
 https://files.klauspost.com/compress/nyc-taxi-data-10M.csv.zst
 
 file                    out level   insize      outsize     millis  mb/s
-nyc-taxi-data-10M.csv   zskp    1   3325605752  641339945   8925    355.35
-nyc-taxi-data-10M.csv   zskp    2   3325605752  591748091   11268   281.44
-nyc-taxi-data-10M.csv   zskp    3   3325605752  530289687   25239   125.66
-nyc-taxi-data-10M.csv   zskp    4   3325605752  476268884   135958  23.33
+nyc-taxi-data-10M.csv   zskp    1   3325605752  641319332   9462    335.17
+nyc-taxi-data-10M.csv   zskp    2   3325605752  588976126   17570   180.50
+nyc-taxi-data-10M.csv   zskp    3   3325605752  529329260   32432   97.79
+nyc-taxi-data-10M.csv   zskp    4   3325605752  474949772   138025  22.98
 
 nyc-taxi-data-10M.csv   zstd    1   3325605752  687399637   8233    385.18
 nyc-taxi-data-10M.csv   zstd    3   3325605752  598514411   10065   315.07
 nyc-taxi-data-10M.csv   zstd    6   3325605752  570522953   20038   158.27
 nyc-taxi-data-10M.csv   zstd    9   3325605752  517554797   64565   49.12
 
-nyc-taxi-data-10M.csv   gzstd   1   3325605752  928656485   23876   132.83
-nyc-taxi-data-10M.csv   gzkp    1   3325605752  922257165   16780   189.00
+nyc-taxi-data-10M.csv   gzstd   1   3325605752  928654908   21270   149.11
+nyc-taxi-data-10M.csv   gzkp    1   3325605752  922273214   13929   227.68
 ```
 
 ## Decompressor
diff --git a/vendor/github.com/klauspost/compress/zstd/blockdec.go b/vendor/github.com/klauspost/compress/zstd/blockdec.go
index 607b62ee3..7d567a54a 100644
--- a/vendor/github.com/klauspost/compress/zstd/blockdec.go
+++ b/vendor/github.com/klauspost/compress/zstd/blockdec.go
@@ -167,6 +167,11 @@ func (b *blockDec) reset(br byteBuffer, windowSize uint64) error {
 			}
 			return ErrCompressedSizeTooBig
 		}
+		// Empty compressed blocks must at least be 2 bytes
+		// for Literals_Block_Type and one for Sequences_Section_Header.
+		if cSize < 2 {
+			return ErrBlockTooSmall
+		}
 	case blockTypeRaw:
 		if cSize > maxCompressedBlockSize || cSize > int(b.WindowSize) {
 			if debugDecoder {
@@ -491,6 +496,9 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 }
 
 func (b *blockDec) prepareSequences(in []byte, hist *history) (err error) {
+	if debugDecoder {
+		printf("prepareSequences: %d byte(s) input\n", len(in))
+	}
 	// Decode Sequences
 	// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#sequences-section
 	if len(in) < 1 {
@@ -499,8 +507,6 @@ func (b *blockDec) prepareSequences(in []byte, hist *history) (err error) {
 	var nSeqs int
 	seqHeader := in[0]
 	switch {
-	case seqHeader == 0:
-		in = in[1:]
 	case seqHeader < 128:
 		nSeqs = int(seqHeader)
 		in = in[1:]
@@ -517,6 +523,13 @@ func (b *blockDec) prepareSequences(in []byte, hist *history) (err error) {
 		nSeqs = 0x7f00 + int(in[1]) + (int(in[2]) << 8)
 		in = in[3:]
 	}
+	if nSeqs == 0 && len(in) != 0 {
+		// When no sequences, there should not be any more data...
+		if debugDecoder {
+			printf("prepareSequences: 0 sequences, but %d byte(s) left on stream\n", len(in))
+		}
+		return ErrUnexpectedBlockSize
+	}
 
 	var seqs = &hist.decoders
 	seqs.nSeqs = nSeqs
@@ -635,6 +648,7 @@ func (b *blockDec) decodeSequences(hist *history) error {
 		hist.decoders.seqSize = len(hist.decoders.literals)
 		return nil
 	}
+	hist.decoders.windowSize = hist.windowSize
 	hist.decoders.prevOffset = hist.recentOffsets
 	err := hist.decoders.decode(b.sequence)
 	hist.recentOffsets = hist.decoders.prevOffset
diff --git a/vendor/github.com/klauspost/compress/zstd/decoder.go b/vendor/github.com/klauspost/compress/zstd/decoder.go
index a93dfaf10..9fcdaac1d 100644
--- a/vendor/github.com/klauspost/compress/zstd/decoder.go
+++ b/vendor/github.com/klauspost/compress/zstd/decoder.go
@@ -348,10 +348,10 @@ func (d *Decoder) DecodeAll(input, dst []byte) ([]byte, error) {
 			frame.history.setDict(&dict)
 		}
 
-		if frame.FrameContentSize > d.o.maxDecodedSize-uint64(len(dst)) {
+		if frame.FrameContentSize != fcsUnknown && frame.FrameContentSize > d.o.maxDecodedSize-uint64(len(dst)) {
 			return dst, ErrDecoderSizeExceeded
 		}
-		if frame.FrameContentSize > 0 && frame.FrameContentSize < 1<<30 {
+		if frame.FrameContentSize < 1<<30 {
 			// Never preallocate more than 1 GB up front.
 			if cap(dst)-len(dst) < int(frame.FrameContentSize) {
 				dst2 := make([]byte, len(dst), len(dst)+int(frame.FrameContentSize))
@@ -514,7 +514,7 @@ func (d *Decoder) nextBlockSync() (ok bool) {
 
 		// Check frame size (before CRC)
 		d.syncStream.decodedFrame += uint64(len(d.current.b))
-		if d.frame.FrameContentSize > 0 && d.syncStream.decodedFrame > d.frame.FrameContentSize {
+		if d.syncStream.decodedFrame > d.frame.FrameContentSize {
 			if debugDecoder {
 				printf("DecodedFrame (%d) > FrameContentSize (%d)\n", d.syncStream.decodedFrame, d.frame.FrameContentSize)
 			}
@@ -523,7 +523,7 @@ func (d *Decoder) nextBlockSync() (ok bool) {
 		}
 
 		// Check FCS
-		if d.current.d.Last && d.frame.FrameContentSize > 0 && d.syncStream.decodedFrame != d.frame.FrameContentSize {
+		if d.current.d.Last && d.frame.FrameContentSize != fcsUnknown && d.syncStream.decodedFrame != d.frame.FrameContentSize {
 			if debugDecoder {
 				printf("DecodedFrame (%d) != FrameContentSize (%d)\n", d.syncStream.decodedFrame, d.frame.FrameContentSize)
 			}
@@ -700,6 +700,7 @@ func (d *Decoder) startStreamDecoder(ctx context.Context, r io.Reader, output ch
 				}
 				hist.decoders = block.async.newHist.decoders
 				hist.recentOffsets = block.async.newHist.recentOffsets
+				hist.windowSize = block.async.newHist.windowSize
 				if block.async.newHist.dict != nil {
 					hist.setDict(block.async.newHist.dict)
 				}
@@ -811,11 +812,11 @@ func (d *Decoder) startStreamDecoder(ctx context.Context, r io.Reader, output ch
 			}
 			if !hasErr {
 				decodedFrame += uint64(len(do.b))
-				if fcs > 0 && decodedFrame > fcs {
+				if decodedFrame > fcs {
 					println("fcs exceeded", block.Last, fcs, decodedFrame)
 					do.err = ErrFrameSizeExceeded
 					hasErr = true
-				} else if block.Last && fcs > 0 && decodedFrame != fcs {
+				} else if block.Last && fcs != fcsUnknown && decodedFrame != fcs {
 					do.err = ErrFrameSizeMismatch
 					hasErr = true
 				} else {
diff --git a/vendor/github.com/klauspost/compress/zstd/framedec.go b/vendor/github.com/klauspost/compress/zstd/framedec.go
index 29c3176b0..11089d223 100644
--- a/vendor/github.com/klauspost/compress/zstd/framedec.go
+++ b/vendor/github.com/klauspost/compress/zstd/framedec.go
@@ -197,7 +197,7 @@ func (d *frameDec) reset(br byteBuffer) error {
 	default:
 		fcsSize = 1 << v
 	}
-	d.FrameContentSize = 0
+	d.FrameContentSize = fcsUnknown
 	if fcsSize > 0 {
 		b, err := br.readSmall(fcsSize)
 		if err != nil {
@@ -343,12 +343,7 @@ func (d *frameDec) runDecoder(dst []byte, dec *blockDec) ([]byte, error) {
 			err = ErrDecoderSizeExceeded
 			break
 		}
-		if d.SingleSegment && uint64(len(d.history.b)) > d.o.maxDecodedSize {
-			println("runDecoder: single segment and", uint64(len(d.history.b)), ">", d.o.maxDecodedSize)
-			err = ErrFrameSizeExceeded
-			break
-		}
-		if d.FrameContentSize > 0 && uint64(len(d.history.b)-crcStart) > d.FrameContentSize {
+		if uint64(len(d.history.b)-crcStart) > d.FrameContentSize {
 			println("runDecoder: FrameContentSize exceeded", uint64(len(d.history.b)-crcStart), ">", d.FrameContentSize)
 			err = ErrFrameSizeExceeded
 			break
@@ -356,13 +351,13 @@ func (d *frameDec) runDecoder(dst []byte, dec *blockDec) ([]byte, error) {
 		if dec.Last {
 			break
 		}
-		if debugDecoder && d.FrameContentSize > 0 {
+		if debugDecoder {
 			println("runDecoder: FrameContentSize", uint64(len(d.history.b)-crcStart), "<=", d.FrameContentSize)
 		}
 	}
 	dst = d.history.b
 	if err == nil {
-		if d.FrameContentSize > 0 && uint64(len(d.history.b)-crcStart) != d.FrameContentSize {
+		if d.FrameContentSize != fcsUnknown && uint64(len(d.history.b)-crcStart) != d.FrameContentSize {
 			err = ErrFrameSizeMismatch
 		} else if d.HasCheckSum {
 			var n int
diff --git a/vendor/github.com/klauspost/compress/zstd/fuzz.go b/vendor/github.com/klauspost/compress/zstd/fuzz.go
index fda8a7422..7f2210e05 100644
--- a/vendor/github.com/klauspost/compress/zstd/fuzz.go
+++ b/vendor/github.com/klauspost/compress/zstd/fuzz.go
@@ -1,5 +1,5 @@
-//go:build gofuzz
-// +build gofuzz
+//go:build ignorecrc
+// +build ignorecrc
 
 // Copyright 2019+ Klaus Post. All rights reserved.
 // License information can be found in the LICENSE file.
diff --git a/vendor/github.com/klauspost/compress/zstd/fuzz_none.go b/vendor/github.com/klauspost/compress/zstd/fuzz_none.go
index 0515b201c..6811c68a8 100644
--- a/vendor/github.com/klauspost/compress/zstd/fuzz_none.go
+++ b/vendor/github.com/klauspost/compress/zstd/fuzz_none.go
@@ -1,5 +1,5 @@
-//go:build !gofuzz
-// +build !gofuzz
+//go:build !ignorecrc
+// +build !ignorecrc
 
 // Copyright 2019+ Klaus Post. All rights reserved.
 // License information can be found in the LICENSE file.
diff --git a/vendor/github.com/klauspost/compress/zstd/seqdec.go b/vendor/github.com/klauspost/compress/zstd/seqdec.go
index 213736ad7..819f1461b 100644
--- a/vendor/github.com/klauspost/compress/zstd/seqdec.go
+++ b/vendor/github.com/klauspost/compress/zstd/seqdec.go
@@ -107,7 +107,10 @@ func (s *sequenceDecs) decode(seqs []seqVals) error {
 	llState, mlState, ofState := s.litLengths.state.state, s.matchLengths.state.state, s.offsets.state.state
 	s.seqSize = 0
 	litRemain := len(s.literals)
-
+	maxBlockSize := maxCompressedBlockSize
+	if s.windowSize < maxBlockSize {
+		maxBlockSize = s.windowSize
+	}
 	for i := range seqs {
 		var ll, mo, ml int
 		if br.off > 4+((maxOffsetBits+16+16)>>3) {
@@ -192,7 +195,7 @@ func (s *sequenceDecs) decode(seqs []seqVals) error {
 		}
 		s.seqSize += ll + ml
 		if s.seqSize > maxBlockSize {
-			return fmt.Errorf("output (%d) bigger than max block size", s.seqSize)
+			return fmt.Errorf("output (%d) bigger than max block size (%d)", s.seqSize, maxBlockSize)
 		}
 		litRemain -= ll
 		if litRemain < 0 {
@@ -230,7 +233,7 @@ func (s *sequenceDecs) decode(seqs []seqVals) error {
 	}
 	s.seqSize += litRemain
 	if s.seqSize > maxBlockSize {
-		return fmt.Errorf("output (%d) bigger than max block size", s.seqSize)
+		return fmt.Errorf("output (%d) bigger than max block size (%d)", s.seqSize, maxBlockSize)
 	}
 	err := br.close()
 	if err != nil {
@@ -347,6 +350,10 @@ func (s *sequenceDecs) decodeSync(history *history) error {
 	llState, mlState, ofState := s.litLengths.state.state, s.matchLengths.state.state, s.offsets.state.state
 	hist := history.b[history.ignoreBuffer:]
 	out := s.out
+	maxBlockSize := maxCompressedBlockSize
+	if s.windowSize < maxBlockSize {
+		maxBlockSize = s.windowSize
+	}
 
 	for i := seqs - 1; i >= 0; i-- {
 		if br.overread() {
@@ -426,7 +433,7 @@ func (s *sequenceDecs) decodeSync(history *history) error {
 		}
 		size := ll + ml + len(out)
 		if size-startSize > maxBlockSize {
-			return fmt.Errorf("output (%d) bigger than max block size", size)
+			return fmt.Errorf("output (%d) bigger than max block size (%d)", size, maxBlockSize)
 		}
 		if size > cap(out) {
 			// Not enough size, which can happen under high volume block streaming conditions
@@ -535,6 +542,11 @@ func (s *sequenceDecs) decodeSync(history *history) error {
 		}
 	}
 
+	// Check if space for literals
+	if len(s.literals)+len(s.out)-startSize > maxBlockSize {
+		return fmt.Errorf("output (%d) bigger than max block size (%d)", len(s.out), maxBlockSize)
+	}
+
 	// Add final literals
 	s.out = append(out, s.literals...)
 	return br.close()
diff --git a/vendor/github.com/klauspost/compress/zstd/zip.go b/vendor/github.com/klauspost/compress/zstd/zip.go
index 967f29b31..ffffcbc25 100644
--- a/vendor/github.com/klauspost/compress/zstd/zip.go
+++ b/vendor/github.com/klauspost/compress/zstd/zip.go
@@ -20,7 +20,7 @@ const ZipMethodPKWare = 20
 
 var zipReaderPool sync.Pool
 
-// newZipReader cannot be used since we would leak goroutines...
+// newZipReader creates a pooled zip decompressor.
 func newZipReader(r io.Reader) io.ReadCloser {
 	dec, ok := zipReaderPool.Get().(*Decoder)
 	if ok {
@@ -44,10 +44,14 @@ func (r *pooledZipReader) Read(p []byte) (n int, err error) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	if r.dec == nil {
-		return 0, errors.New("Read after Close")
+		return 0, errors.New("read after close or EOF")
 	}
 	dec, err := r.dec.Read(p)
-
+	if err == io.EOF {
+		err = r.dec.Reset(nil)
+		zipReaderPool.Put(r.dec)
+		r.dec = nil
+	}
 	return dec, err
 }
 
@@ -112,11 +116,5 @@ func ZipCompressor(opts ...EOption) func(w io.Writer) (io.WriteCloser, error) {
 // ZipDecompressor returns a decompressor that can be registered with zip libraries.
 // See ZipCompressor for example.
 func ZipDecompressor() func(r io.Reader) io.ReadCloser {
-	return func(r io.Reader) io.ReadCloser {
-		d, err := NewReader(r, WithDecoderConcurrency(1), WithDecoderLowmem(true))
-		if err != nil {
-			panic(err)
-		}
-		return d.IOReadCloser()
-	}
+	return newZipReader
 }
diff --git a/vendor/github.com/klauspost/compress/zstd/zstd.go b/vendor/github.com/klauspost/compress/zstd/zstd.go
index 0b0c2571d..c1c90b4a0 100644
--- a/vendor/github.com/klauspost/compress/zstd/zstd.go
+++ b/vendor/github.com/klauspost/compress/zstd/zstd.go
@@ -39,6 +39,9 @@ const zstdMinMatch = 3
 // Reset the buffer offset when reaching this.
 const bufferReset = math.MaxInt32 - MaxWindowSize
 
+// fcsUnknown is used for unknown frame content size.
+const fcsUnknown = math.MaxUint64
+
 var (
 	// ErrReservedBlockType is returned when a reserved block type is found.
 	// Typically this indicates wrong or corrupted input.
@@ -52,6 +55,10 @@ var (
 	// Typically returned on invalid input.
 	ErrBlockTooSmall = errors.New("block too small")
 
+	// ErrUnexpectedBlockSize is returned when a block has unexpected size.
+	// Typically returned on invalid input.
+	ErrUnexpectedBlockSize = errors.New("unexpected block size")
+
 	// ErrMagicMismatch is returned when a "magic" number isn't what is expected.
 	// Typically this indicates wrong or corrupted input.
 	ErrMagicMismatch = errors.New("invalid input: magic number mismatch")