Return length from StatelessDeflate

README.md

@@ -15,6 +15,7 @@ This package provides various compression algorithms.
 
 # changelog
 
+* Feb 14, 2020: Return a length from [stateless deflate](https://pkg.go.dev/github.com/klauspost/compress/flate?tab=doc#StatelessDeflate) to indicate the bytes written. Breaking change.
 * Feb 4, 2020: (v1.10.0) Add optional dictionary to [stateless deflate](https://pkg.go.dev/github.com/klauspost/compress/flate?tab=doc#StatelessDeflate). Breaking change, send `nil` for previous behaviour. [#216](https://github.com/klauspost/compress/pull/216)
 * Feb 3, 2020: Fix buffer overflow on repeated small block deflate.  [#218](https://github.com/klauspost/compress/pull/218)
 * Jan 31, 2020: Allow copying content from an existing ZIP file without decompressing+compressing. [#214](https://github.com/klauspost/compress/pull/214)

flate/flate_test.go

@@ -141,14 +141,14 @@ func TestRegressions(t *testing.T) {
 		t.Run(tt.Name+"stateless", func(t *testing.T) {
 			// Split into two and use history...
 			buf := new(bytes.Buffer)
-			err = StatelessDeflate(buf, data1[:len(data1)/2], false, nil)
+			_, err = StatelessDeflate(buf, data1[:len(data1)/2], false, nil)
 			if err != nil {
 				t.Error(err)
 			}
 
 			// Use top half as dictionary...
 			dict := data1[:len(data1)/2]
-			err = StatelessDeflate(buf, data1[len(data1)/2:], true, dict)
+			_, err = StatelessDeflate(buf, data1[len(data1)/2:], true, dict)
 			if err != nil {
 				t.Error(err)
 			}

flate/stateless.go

@@ -27,15 +27,12 @@ func (s *statelessWriter) Close() error {
 	}
 	s.closed = true
 	// Emit EOF block
-	return StatelessDeflate(s.dst, nil, true, nil)
+	_, err := StatelessDeflate(s.dst, nil, true, nil)
+	return err
 }
 
-func (s *statelessWriter) Write(p []byte) (n int, err error) {
-	err = StatelessDeflate(s.dst, p, false, nil)
-	if err != nil {
-		return 0, err
-	}
-	return len(p), nil
+func (s *statelessWriter) Write(p []byte) (int, error) {
+	return StatelessDeflate(s.dst, p, false, nil)
 }
 
 func (s *statelessWriter) Reset(w io.Writer) {
@@ -64,7 +61,7 @@ var bitWriterPool = sync.Pool{
 // Up to 8KB of an optional dictionary can be given which is presumed to presumed to precede the block.
 // Longer dictionaries will be truncated and will still produce valid output.
 // Sending nil dictionary is perfectly fine.
-func StatelessDeflate(out io.Writer, in []byte, eof bool, dict []byte) error {
+func StatelessDeflate(out io.Writer, in []byte, eof bool, dict []byte) (int, error) {
 	var dst tokens
 	bw := bitWriterPool.Get().(*huffmanBitWriter)
 	bw.reset(out)
@@ -78,7 +75,7 @@ func StatelessDeflate(out io.Writer, in []byte, eof bool, dict []byte) error {
 		// Could be faster...
 		bw.writeStoredHeader(0, true)
 		bw.flush()
-		return bw.err
+		return 0, bw.err
 	}
 
 	// Truncate dict
@@ -108,7 +105,7 @@ func StatelessDeflate(out io.Writer, in []byte, eof bool, dict []byte) error {
 		if dst.n == 0 {
 			bw.writeStoredHeader(len(uncompressed), isEof)
 			if bw.err != nil {
-				return bw.err
+				return 0, bw.err
 			}
 			bw.writeBytes(uncompressed)
 		} else if int(dst.n) > len(uncompressed)-len(uncompressed)>>4 {
@@ -123,15 +120,15 @@ func StatelessDeflate(out io.Writer, in []byte, eof bool, dict []byte) error {
 			dst.Reset()
 		}
 		if bw.err != nil {
-			return bw.err
+			return 0, bw.err
 		}
 	}
 	if !eof {
 		// Align, only a stored block can do that.
 		bw.writeStoredHeader(0, false)
 	}
 	bw.flush()
-	return bw.err
+	return len(in), bw.err
 }
 
 func hashSL(u uint32) uint32 {

gzip/gzip.go

@@ -207,7 +207,7 @@ func (z *Writer) Write(p []byte) (int, error) {
 	z.size += uint32(len(p))
 	z.digest = crc32.Update(z.digest, crc32.IEEETable, p)
 	if z.level == StatelessCompression {
-		return len(p), flate.StatelessDeflate(z.w, p, false, nil)
+		return flate.StatelessDeflate(z.w, p, false, nil)
 	}
 	n, z.err = z.compressor.Write(p)
 	return n, z.err
@@ -255,7 +255,7 @@ func (z *Writer) Close() error {
 		}
 	}
 	if z.level == StatelessCompression {
-		z.err = flate.StatelessDeflate(z.w, nil, true, nil)
+		_, z.err = flate.StatelessDeflate(z.w, nil, true, nil)
 	} else {
 		z.err = z.compressor.Close()
 	}