Update vendor for next release (#1343)

vendor/golang.org/x/image/tiff/compress.go

@@ -0,0 +1,58 @@
+// Copyright 2011 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 tiff
+
+import (
+	"bufio"
+	"io"
+)
+
+type byteReader interface {
+	io.Reader
+	io.ByteReader
+}
+
+// unpackBits decodes the PackBits-compressed data in src and returns the
+// uncompressed data.
+//
+// The PackBits compression format is described in section 9 (p. 42)
+// of the TIFF spec.
+func unpackBits(r io.Reader) ([]byte, error) {
+	buf := make([]byte, 128)
+	dst := make([]byte, 0, 1024)
+	br, ok := r.(byteReader)
+	if !ok {
+		br = bufio.NewReader(r)
+	}
+
+	for {
+		b, err := br.ReadByte()
+		if err != nil {
+			if err == io.EOF {
+				return dst, nil
+			}
+			return nil, err
+		}
+		code := int(int8(b))
+		switch {
+		case code >= 0:
+			n, err := io.ReadFull(br, buf[:code+1])
+			if err != nil {
+				return nil, err
+			}
+			dst = append(dst, buf[:n]...)
+		case code == -128:
+			// No-op.
+		default:
+			if b, err = br.ReadByte(); err != nil {
+				return nil, err
+			}
+			for j := 0; j < 1-code; j++ {
+				buf[j] = b
+			}
+			dst = append(dst, buf[:1-code]...)
+		}
+	}
+}