Simplify go brotli wrapper. (#540)
Based on PR #533.
Kudos to Bryan (bcmillis@).
diff --git a/go/cbrotli/BUILD b/go/cbrotli/BUILD
index 4bea8a0..e045b61 100755
--- a/go/cbrotli/BUILD
+++ b/go/cbrotli/BUILD
@@ -2,16 +2,19 @@
licenses(["notice"]) # MIT
-load("@io_bazel_rules_go//go:def.bzl", "go_prefix", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_prefix", "cgo_library", "go_test")
go_prefix("github.com/google/brotli")
-go_library(
+cgo_library(
name = "cbrotli",
- srcs = ["cbrotli.go"],
- deps = [
- "//go/cbrotli/internal:decoder",
- "//go/cbrotli/internal:encoder",
+ srcs = [
+ "reader.go",
+ "writer.go",
+ ],
+ cdeps = [
+ "//:brotlidec",
+ "//:brotlienc",
],
)
diff --git a/go/cbrotli/cbrotli.go b/go/cbrotli/cbrotli.go
deleted file mode 100755
index a7009d0..0000000
--- a/go/cbrotli/cbrotli.go
+++ /dev/null
@@ -1,254 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Distributed under MIT license.
-// See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
-
-// Package cbrotli compresses and decompresses data with C-Brotli library.
-package cbrotli
-
-import (
- "bytes"
- "io"
-
- "github.com/google/brotli/go/cbrotli/internal/decoder"
- "github.com/google/brotli/go/cbrotli/internal/encoder"
-)
-
-// An internalError reports an error in the (c-)brotli code itself.
-type internalError string
-
-func (e internalError) Error() string {
- return "cbrotli: internal error: " + string(e)
-}
-
-//------------------------------------------------------------------------------
-// Encoder
-//------------------------------------------------------------------------------
-
-// WriterOptions configures Writer.
-type WriterOptions struct {
- // Quality controls the compression-speed vs compression-density trade-offs.
- // The higher the quality, the slower the compression. Range is 0 to 11.
- Quality int
- // LGWin is the base 2 logarithm of the sliding window size.
- // Range is 10 to 24. 0 indicates automatic configuration based on Quality.
- LGWin int
-}
-
-// Writer implements io.WriteCloser, an io.Writer decorator that produces
-// Brotli-encoded data.
-type Writer struct {
- dst io.Writer
- encoder encoder.Encoder
- closed bool
-}
-
-// NewWriter initializes new Writer instance.
-// Close MUST be called to free resources.
-func NewWriter(dst io.Writer, options WriterOptions) *Writer {
- return &Writer{
- dst: dst,
- encoder: encoder.New(options.Quality, options.LGWin),
- }
-}
-
-// Close implements io.Closer. Close MUST be invoked to free native resources.
-// Also Close implicitly flushes remaining data to the decorated writer.
-func (z *Writer) Close() error {
- if z.closed {
- return nil
- }
- defer z.encoder.Close()
- _, err := z.writeChunk(nil, encoder.Finish)
- z.closed = true
- return err
-}
-
-func (z *Writer) writeChunk(p []byte, op encoder.Operation) (int, error) {
- if z.closed {
- return 0, internalError("write after close")
- }
- var totalBytesConsumed int
- var err error
- for {
- bytesConsumed, output, status := z.encoder.CompressStream(p, op)
- if status == encoder.Error {
- err = internalError("encoder failure")
- break
- }
- p = p[bytesConsumed:]
- totalBytesConsumed += bytesConsumed
- _, err = z.dst.Write(output)
- if err != nil {
- break
- }
- if len(p) == 0 && status == encoder.Done {
- break
- }
- }
- return totalBytesConsumed, err
-}
-
-// Write implements io.Writer.
-func (z *Writer) Write(p []byte) (int, error) {
- return z.writeChunk(p, encoder.Process)
-}
-
-// Flush outputs encoded data for all input provided to Write. The resulting
-// output can be decoded to match all input before Flush, but the stream is
-// not yet complete until after Close.
-// Flush has a negative impact on compression.
-func (z *Writer) Flush() error {
- _, err := z.writeChunk(nil, encoder.Finish)
- return err
-}
-
-// Encode returns content encoded with Brotli.
-func Encode(content []byte, options WriterOptions) ([]byte, error) {
- var buf bytes.Buffer
- writer := NewWriter(&buf, options)
- defer writer.Close()
- _, err := writer.Write(content)
- if err != nil {
- return nil, err
- }
- if err := writer.Close(); err != nil {
- return nil, err
- }
- return buf.Bytes(), nil
-}
-
-//------------------------------------------------------------------------------
-// Decoder
-//------------------------------------------------------------------------------
-
-// Reader implements io.ReadCloser, an io.Reader decorator that decodes
-// Brotli-encoded data.
-type Reader struct {
- src io.Reader
- decoder decoder.Decoder
- buf []byte // intermediate read buffer pointed to by next
- eof bool // true if all compressed stream is decoded
- next []byte // buffered data to be passed to decoder
- output []byte // data produced by decoder, but not yet consumed
- srcErr error // last source reader error
- err error // reader state; nil if it is OK to read further
- closed bool // true is stream is already closed
-}
-
-// NewReader initializes new Reader instance.
-// Close MUST be called to free resources.
-func NewReader(src io.Reader) *Reader {
- return &Reader{
- src: src,
- decoder: decoder.New(),
- buf: make([]byte, 32*1024),
- eof: false,
- }
-}
-
-// Close implements io.Closer. Close MUST be invoked to free native resources.
-func (z *Reader) Close() error {
- if z.closed {
- return nil
- }
- z.decoder.Close()
- z.err = internalError("read after close")
- z.closed = true
- return nil
-}
-
-func isEOF(src io.Reader) bool {
- n, err := src.Read(make([]byte, 1))
- return n == 0 && err == io.EOF
-}
-
-// Read implements io.Reader.
-func (z *Reader) Read(p []byte) (int, error) {
- // Any error state is unrecoverable.
- if z.err != nil {
- return 0, z.err
- }
- // See io.Reader documentation.
- if len(p) == 0 {
- return 0, nil
- }
-
- var totalOutBytes int
-
- // There is no practical limit for amount of bytes being consumed by decoder
- // before producing any output. Continue feeding decoder until some data is
- // produced
- for {
- // Push already produced output first.
- if outBytes := len(z.output); outBytes != 0 {
- outBytes = copy(p, z.output)
- p = p[outBytes:]
- z.output = z.output[outBytes:]
- totalOutBytes += outBytes
- // Output buffer is full.
- if len(p) == 0 {
- break
- }
- continue
- }
- // No more produced output left.
- // If no more output is expected, then we are finished.
- if z.eof {
- z.err = io.EOF
- break
- }
- // Replenish buffer (might cause blocking read), only if necessary.
- if len(z.next) == 0 && totalOutBytes == 0 && z.srcErr != io.EOF {
- var n int
- n, z.srcErr = z.src.Read(z.buf)
- z.next = z.buf[:n]
- if z.srcErr != nil && z.srcErr != io.EOF {
- z.err = z.srcErr
- break
- }
- }
- // Do decoding.
- consumed, output, status := z.decoder.DecompressStream(z.next)
- z.output = output
- z.next = z.next[consumed:]
- if status == decoder.Error {
- // When error happens, the remaining output does not matter.
- z.err = internalError("decoder failure")
- break
- } else if status == decoder.Done {
- // Decoder stream is closed; no further input is expected.
- if len(z.next) != 0 || (z.srcErr != io.EOF && !isEOF(z.src)) {
- z.err = internalError("excessive input")
- break
- }
- // No more output is expected; keep pushing output.
- z.eof = true
- continue
- } else {
- // If can not move any further...
- if consumed == 0 && len(z.output) == 0 {
- // Unexpected end of input.
- if z.srcErr == io.EOF || totalOutBytes == 0 {
- z.err = io.ErrUnexpectedEOF
- }
- // Postpone blocking reads for the next invocation.
- break
- }
- // Continue pushing output.
- }
- }
- return totalOutBytes, z.err
-}
-
-// Decode decodes Brotli encoded data.
-func Decode(encodedData []byte) ([]byte, error) {
- var buf bytes.Buffer
- reader := NewReader(bytes.NewReader(encodedData))
- defer reader.Close()
- _, err := io.Copy(&buf, reader)
- if err != nil {
- return nil, err
- }
- return buf.Bytes(), nil
-}
diff --git a/go/cbrotli/cbrotli_test.go b/go/cbrotli/cbrotli_test.go
index 4fe0960..0a9368b 100755
--- a/go/cbrotli/cbrotli_test.go
+++ b/go/cbrotli/cbrotli_test.go
@@ -91,7 +91,7 @@
// to fill the window.
const lgWin = 16
windowSize := int(math.Pow(2, lgWin))
- input := make([]byte, 2*windowSize)
+ input := make([]byte, 8*windowSize)
rand.Read(input)
out := bytes.Buffer{}
e := NewWriter(&out, WriterOptions{Quality: 11, LGWin: lgWin})
@@ -106,7 +106,7 @@
// We've fed more data than the sliding window size. Check that some
// compressed data has been output.
if out.Len() == 0 {
- t.Errorf("Output length is after %d bytes written", n)
+ t.Errorf("Output length is 0 after %d bytes written", n)
}
if err := e.Close(); err != nil {
t.Errorf("Close Error after copied %d bytes: %v", n, err)
@@ -151,6 +151,9 @@
if err := e.Flush(); err != nil {
t.Fatalf("Flush(): %v", err)
}
+ if out.Len() == 0 {
+ t.Fatalf("0 bytes written after Flush()")
+ }
decompressed := make([]byte, 1000)
reader := NewReader(bytes.NewReader(out.Bytes()))
n, err := reader.Read(decompressed)
@@ -187,8 +190,8 @@
"Reader output:\n"+
"%q\n"+
"want:\n"+
- "%q",
- got, content)
+ "<%d bytes>",
+ got, len(content))
}
}
@@ -204,8 +207,8 @@
"Decode content:\n"+
"%q\n"+
"want:\n"+
- "%q",
- decoded, content)
+ "<%d bytes>",
+ decoded, len(content))
}
}
@@ -213,7 +216,13 @@
// Test that the decoder terminates with corrupted input.
content := bytes.Repeat([]byte("hello world!"), 100)
src := rand.NewSource(0)
- encoded, _ := Encode(content, WriterOptions{Quality: 5})
+ encoded, err := Encode(content, WriterOptions{Quality: 5})
+ if err != nil {
+ t.Fatalf("Encode(<%d bytes>, _) = _, %s", len(content), err)
+ }
+ if len(encoded) == 0 {
+ t.Fatalf("Encode(<%d bytes>, _) produced empty output", len(content))
+ }
for i := 0; i < 100; i++ {
enc := append([]byte{}, encoded...)
for j := 0; j < 5; j++ {
@@ -260,12 +269,18 @@
t.Errorf("Decode: %v", err)
}
if !bytes.Equal(decoded, input) {
+ var want string
+ if len(input) > 320 {
+ want = fmt.Sprintf("<%d bytes>", len(input))
+ } else {
+ want = fmt.Sprintf("%q", input)
+ }
t.Errorf(""+
"Decode content:\n"+
"%q\n"+
"want:\n"+
- "%q",
- decoded, input)
+ "%s",
+ decoded, want)
}
}
}
diff --git a/go/cbrotli/internal/BUILD b/go/cbrotli/internal/BUILD
deleted file mode 100755
index a3e3b87..0000000
--- a/go/cbrotli/internal/BUILD
+++ /dev/null
@@ -1,19 +0,0 @@
-package(default_visibility = ["//visibility:public"])
-
-licenses(["notice"]) # MIT
-
-load("@io_bazel_rules_go//go:def.bzl", "cgo_library")
-
-cgo_library(
- name = "decoder",
- srcs = ["decoder.go"],
- visibility = ["//go/cbrotli:__subpackages__"],
- cdeps = ["//:brotlidec"],
-)
-
-cgo_library(
- name = "encoder",
- srcs = ["encoder.go"],
- visibility = ["//go/cbrotli:__subpackages__"],
- cdeps = ["//:brotlienc"],
-)
diff --git a/go/cbrotli/internal/decoder.go b/go/cbrotli/internal/decoder.go
deleted file mode 100755
index 74d4c21..0000000
--- a/go/cbrotli/internal/decoder.go
+++ /dev/null
@@ -1,110 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Distributed under MIT license.
-// See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
-
-// Package decoder wraps the brotli decoder C API used by package brotli.
-package decoder
-
-/*
-#include <brotli/decode.h>
-
-// Wrap BrotliDecoderDecompressStream so that it doesn't take variable (in-out)
-// pointers. Instead of updated pointer, deltas are saved in auxiliary struct.
-
-struct DecompressStreamResult {
- size_t bytes_consumed;
- const uint8_t* output_data;
- size_t output_data_size;
- BrotliDecoderResult status;
-};
-
-struct DecompressStreamResult DecompressStream(BrotliDecoderState* s,
- const uint8_t* encoded_data, size_t encoded_data_size) {
- struct DecompressStreamResult result;
- size_t available_in = encoded_data_size;
- const uint8_t* next_in = encoded_data;
- size_t available_out = 0;
- result.status = BrotliDecoderDecompressStream(s,
- &available_in, &next_in, &available_out, 0, 0);
- result.bytes_consumed = encoded_data_size - available_in;
- result.output_data = 0;
- result.output_data_size = 0;
- if (result.status != BROTLI_DECODER_RESULT_ERROR) {
- result.output_data = BrotliDecoderTakeOutput(s, &result.output_data_size);
- if (BrotliDecoderIsFinished(s)) {
- result.status = BROTLI_DECODER_RESULT_SUCCESS;
- }
- }
- return result;
-}
-
-*/
-import "C"
-import (
- "unsafe"
-)
-
-// Status represents internal state after DecompressStream invokation
-type Status int
-
-const (
- // Error happened
- Error Status = iota
- // Done means that no more output will be produced
- Done
- // Ok means that more output might be produced with no additional input
- Ok
-)
-
-// Decoder is the Brotli c-decoder handle.
-type Decoder struct {
- state *C.BrotliDecoderState
-}
-
-// New returns a new Brotli c-decoder handle.
-// Close MUST be called to free resources.
-func New() Decoder {
- return Decoder{state: C.BrotliDecoderCreateInstance(nil, nil, nil)}
-}
-
-// Close frees resources used by decoder.
-func (z *Decoder) Close() {
- C.BrotliDecoderDestroyInstance(z.state)
- z.state = nil
-}
-
-func goStatus(cStatus C.BrotliDecoderResult) (status Status) {
- switch cStatus {
- case C.BROTLI_DECODER_RESULT_SUCCESS:
- return Done
- case C.BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT:
- return Ok
- case C.BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT:
- return Ok
- }
- return Error
-}
-
-// cBytes casts a Go []byte into a C uint8_t*. We pass &buf[0] directly to C,
-// which is legal because C doesn't save the pointer longer than the call and
-// the byte array itself doesn't contain any pointers.
-func cBytes(buf []byte) (*C.uint8_t, C.size_t) {
- if len(buf) == 0 {
- return (*C.uint8_t)(nil), 0
- }
- return (*C.uint8_t)(unsafe.Pointer(&buf[0])), C.size_t(len(buf))
-}
-
-// DecompressStream reads Brotli-encoded bytes from in, and returns produced
-// bytes. Output contents should not be modified. Liveness of output is
-// hard-limited by Decoder liveness; slice becomes invalid when any Decoder
-// method is invoked.
-func (z *Decoder) DecompressStream(in []byte) (
- bytesConsumed int, output []byte, status Status) {
- cin, cinSize := cBytes(in)
- result := C.DecompressStream(z.state, cin, cinSize)
- output = C.GoBytes(
- unsafe.Pointer(result.output_data), C.int(result.output_data_size))
- return int(result.bytes_consumed), output, goStatus(result.status)
-}
diff --git a/go/cbrotli/internal/encoder.go b/go/cbrotli/internal/encoder.go
deleted file mode 100755
index 13526f3..0000000
--- a/go/cbrotli/internal/encoder.go
+++ /dev/null
@@ -1,134 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Distributed under MIT license.
-// See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
-
-// Package encoder wraps the brotli encoder C API used by package brotli.
-package encoder
-
-/*
-#include <brotli/encode.h>
-
-// Wrap BrotliEncoderCompressStream so that it doesn't take variable (in-out)
-// pointers. Instead of updated pointer, deltas are saved in auxiliary struct.
-struct CompressStreamResult {
- size_t bytes_consumed;
- const uint8_t* output_data;
- size_t output_data_size;
- int success;
- int has_more;
-};
-
-struct CompressStreamResult CompressStream(
- BrotliEncoderState* s, BrotliEncoderOperation op,
- const uint8_t* data, size_t data_size) {
- struct CompressStreamResult result;
- size_t available_in = data_size;
- const uint8_t* next_in = data;
- size_t available_out = 0;
- result.success = BrotliEncoderCompressStream(s, op,
- &available_in, &next_in, &available_out, 0, 0) ? 1 : 0;
- result.bytes_consumed = data_size - available_in;
- result.output_data = 0;
- result.output_data_size = 0;
- if (result.success) {
- result.output_data = BrotliEncoderTakeOutput(s, &result.output_data_size);
- }
- result.has_more = BrotliEncoderHasMoreOutput(s) ? 1 : 0;
- return result;
-}
-*/
-import "C"
-import (
- "unsafe"
-)
-
-// Operation represents type of request to CompressStream
-type Operation int
-
-const (
- // Process input
- Process Operation = iota
- // Flush input processed so far
- Flush
- // Finish stream
- Finish
-)
-
-// Status represents internal state after CompressStream invocation
-type Status int
-
-const (
- // Error happened
- Error Status = iota
- // Done means that no more output will be produced
- Done
- // Ok means that more output might be produced with no additional input
- Ok
-)
-
-// Encoder is the Brotli c-encoder handle.
-type Encoder struct {
- state *C.BrotliEncoderState
-}
-
-// New returns a new Brotli c-encoder handle.
-// quality and lgWin are described in third_party/Brotli/enc/encode.h.
-// Close MUST be called to free resources.
-func New(quality, lgWin int) Encoder {
- state := C.BrotliEncoderCreateInstance(nil, nil, nil)
- C.BrotliEncoderSetParameter(
- state, C.BROTLI_PARAM_QUALITY, (C.uint32_t)(quality))
- C.BrotliEncoderSetParameter(
- state, C.BROTLI_PARAM_LGWIN, (C.uint32_t)(lgWin))
- return Encoder{state}
-}
-
-// Close frees resources used by encoder.
-func (z *Encoder) Close() {
- C.BrotliEncoderDestroyInstance(z.state)
- z.state = nil
-}
-
-// cBytes casts a Go []byte into a C uint8_t*. We pass &buf[0] directly to C,
-// which is legal because C doesn't save the pointer longer than the call and
-// the byte array itself doesn't contain any pointers.
-func cBytes(buf []byte) (*C.uint8_t, C.size_t) {
- if len(buf) == 0 {
- return (*C.uint8_t)(nil), 0
- }
- return (*C.uint8_t)(unsafe.Pointer(&buf[0])), C.size_t(len(buf))
-}
-
-func cOperation(op Operation) (cOp C.BrotliEncoderOperation) {
- switch op {
- case Flush:
- return C.BROTLI_OPERATION_FLUSH
- case Finish:
- return C.BROTLI_OPERATION_FINISH
- }
- return C.BROTLI_OPERATION_PROCESS
-}
-
-// CompressStream processes data and produces Brotli-encoded bytes. Encoder may
-// consume considerable amount of input before the first output bytes come out.
-// Flush and Finish operations force Encoder to produce output that corresponds
-// to input consumed so far. Output contents should not be modified. Liveness of
-// output is hard-limited by Encoder liveness; slice becomes invalid when any
-// Encoder method is invoked.
-func (z *Encoder) CompressStream(in []byte, op Operation) (
- bytesConsumed int, output []byte, status Status) {
- cin, cinSize := cBytes(in)
- result := C.CompressStream(z.state, cOperation(op), cin, cinSize)
- output = C.GoBytes(
- unsafe.Pointer(result.output_data), C.int(result.output_data_size))
- var outcome Status
- if result.success == 0 {
- outcome = Error
- } else if result.has_more != 0 {
- outcome = Ok
- } else {
- outcome = Done
- }
- return int(result.bytes_consumed), output, outcome
-}
diff --git a/go/cbrotli/reader.go b/go/cbrotli/reader.go
new file mode 100755
index 0000000..a05809b
--- /dev/null
+++ b/go/cbrotli/reader.go
@@ -0,0 +1,156 @@
+// Copyright 2016 Google Inc. All Rights Reserved.
+//
+// Distributed under MIT license.
+// See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+
+// Package cbrotli compresses and decompresses data with C-Brotli library.
+package cbrotli
+
+/*
+#include <stddef.h>
+#include <stdint.h>
+
+#include <brotli/decode.h>
+
+static BrotliDecoderResult DecompressStream(BrotliDecoderState* s,
+ uint8_t* out, size_t out_len,
+ const uint8_t* in, size_t in_len,
+ size_t* bytes_written,
+ size_t* bytes_consumed) {
+ size_t in_remaining = in_len;
+ size_t out_remaining = out_len;
+ BrotliDecoderResult result = BrotliDecoderDecompressStream(
+ s, &in_remaining, &in, &out_remaining, &out, NULL);
+ *bytes_written = out_len - out_remaining;
+ *bytes_consumed = in_len - in_remaining;
+ return result;
+}
+*/
+import "C"
+
+import (
+ "bytes"
+ "errors"
+ "io"
+ "io/ioutil"
+)
+
+type decodeError C.BrotliDecoderErrorCode
+
+func (err decodeError) Error() string {
+ return "cbrotli: " +
+ C.GoString(C.BrotliDecoderErrorString(C.BrotliDecoderErrorCode(err)))
+}
+
+var errExcessiveInput = errors.New("cbrotli: excessive input")
+var errInvalidState = errors.New("cbrotli: invalid state")
+var errReaderClosed = errors.New("cbrotli: Reader is closed")
+
+// Reader implements io.ReadCloser by reading Brotli-encoded data from an
+// underlying Reader.
+type Reader struct {
+ src io.Reader
+ state *C.BrotliDecoderState
+ buf []byte // scratch space for reading from src
+ in []byte // current chunk to decode; usually aliases buf
+}
+
+// readBufSize is a "good" buffer size that avoids excessive round-trips
+// between C and Go but doesn't waste too much memory on buffering.
+// It is arbitrarily chosen to be equal to the constant used in io.Copy.
+const readBufSize = 32 * 1024
+
+// NewReader initializes new Reader instance.
+// Close MUST be called to free resources.
+func NewReader(src io.Reader) *Reader {
+ return &Reader{
+ src: src,
+ state: C.BrotliDecoderCreateInstance(nil, nil, nil),
+ buf: make([]byte, readBufSize),
+ }
+}
+
+// Close implements io.Closer. Close MUST be invoked to free native resources.
+func (r *Reader) Close() error {
+ if r.state == nil {
+ return errReaderClosed
+ }
+ // Close despite the state; i.e. there might be some unread decoded data.
+ C.BrotliDecoderDestroyInstance(r.state)
+ r.state = nil
+ return nil
+}
+
+func (r *Reader) Read(p []byte) (n int, err error) {
+ if int(C.BrotliDecoderHasMoreOutput(r.state)) == 0 && len(r.in) == 0 {
+ m, readErr := r.src.Read(r.buf)
+ if m == 0 {
+ // If readErr is `nil`, we just proxy underlying stream behavior.
+ return 0, readErr
+ }
+ r.in = r.buf[:m]
+ }
+
+ if len(p) == 0 {
+ return 0, nil
+ }
+
+ for n == 0 {
+ var written, consumed C.size_t
+ var data *C.uint8_t
+ if len(r.in) != 0 {
+ data = (*C.uint8_t)(&r.in[0])
+ }
+ result := C.DecompressStream(r.state,
+ (*C.uint8_t)(&p[0]), C.size_t(len(p)),
+ data, C.size_t(len(r.in)),
+ &written, &consumed)
+ r.in = r.in[int(consumed):]
+ n = int(written)
+
+ switch result {
+ case C.BROTLI_DECODER_RESULT_SUCCESS:
+ if len(r.in) > 0 {
+ return n, errExcessiveInput
+ }
+ return n, nil
+ case C.BROTLI_DECODER_RESULT_ERROR:
+ return n, decodeError(C.BrotliDecoderGetErrorCode(r.state))
+ case C.BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT:
+ if n == 0 {
+ return 0, io.ErrShortBuffer
+ }
+ return n, nil
+ case C.BROTLI_DECODER_NEEDS_MORE_INPUT:
+ }
+
+ if len(r.in) != 0 {
+ return 0, errInvalidState
+ }
+
+ // Top off the buffer.
+ encN, err := r.src.Read(r.buf)
+ if encN == 0 && n == 0 {
+ // Not enough data to complete decoding.
+ if err == io.EOF {
+ return 0, io.ErrUnexpectedEOF
+ }
+ return 0, err
+ }
+ r.in = r.buf[:encN]
+ }
+
+ return n, nil
+}
+
+// Decode decodes Brotli encoded data.
+func Decode(encodedData []byte) ([]byte, error) {
+ r := &Reader{
+ src: bytes.NewReader(nil),
+ state: C.BrotliDecoderCreateInstance(nil, nil, nil),
+ buf: make([]byte, 4), // arbitrarily small but nonzero so that r.src.Read returns io.EOF
+ in: encodedData,
+ }
+ defer r.Close()
+ return ioutil.ReadAll(r)
+}
diff --git a/go/cbrotli/writer.go b/go/cbrotli/writer.go
new file mode 100755
index 0000000..279a2f2
--- /dev/null
+++ b/go/cbrotli/writer.go
@@ -0,0 +1,160 @@
+// Copyright 2016 Google Inc. All Rights Reserved.
+//
+// Distributed under MIT license.
+// See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+
+package cbrotli
+
+/*
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <brotli/encode.h>
+
+struct CompressStreamResult {
+ size_t bytes_consumed;
+ const uint8_t* output_data;
+ size_t output_data_size;
+ int success;
+ int has_more;
+};
+
+static struct CompressStreamResult CompressStream(
+ BrotliEncoderState* s, BrotliEncoderOperation op,
+ const uint8_t* data, size_t data_size) {
+ struct CompressStreamResult result;
+ size_t available_in = data_size;
+ const uint8_t* next_in = data;
+ size_t available_out = 0;
+ result.success = BrotliEncoderCompressStream(s, op,
+ &available_in, &next_in, &available_out, 0, 0) ? 1 : 0;
+ result.bytes_consumed = data_size - available_in;
+ result.output_data = 0;
+ result.output_data_size = 0;
+ if (result.success) {
+ result.output_data = BrotliEncoderTakeOutput(s, &result.output_data_size);
+ }
+ result.has_more = BrotliEncoderHasMoreOutput(s) ? 1 : 0;
+ return result;
+}
+*/
+import "C"
+
+import (
+ "bytes"
+ "errors"
+ "io"
+ "unsafe"
+)
+
+// WriterOptions configures Writer.
+type WriterOptions struct {
+ // Quality controls the compression-speed vs compression-density trade-offs.
+ // The higher the quality, the slower the compression. Range is 0 to 11.
+ Quality int
+ // LGWin is the base 2 logarithm of the sliding window size.
+ // Range is 10 to 24. 0 indicates automatic configuration based on Quality.
+ LGWin int
+ // BufferSize is the number of bytes to use to buffer encoded output.
+ // 0 indicates an implementation-defined default.
+ BufferSize int
+}
+
+// Writer implements io.WriteCloser by writing Brotli-encoded data to an
+// underlying Writer.
+type Writer struct {
+ dst io.Writer
+ state *C.BrotliEncoderState
+ buf, encoded []byte
+}
+
+var (
+ errEncode = errors.New("cbrotli: encode error")
+ errWriterClosed = errors.New("cbrotli: Writer is closed")
+)
+
+// NewWriter initializes new Writer instance.
+// Close MUST be called to free resources.
+func NewWriter(dst io.Writer, options WriterOptions) *Writer {
+ state := C.BrotliEncoderCreateInstance(nil, nil, nil)
+ C.BrotliEncoderSetParameter(
+ state, C.BROTLI_PARAM_QUALITY, (C.uint32_t)(options.Quality))
+ C.BrotliEncoderSetParameter(
+ state, C.BROTLI_PARAM_LGWIN, (C.uint32_t)(options.LGWin))
+ return &Writer{
+ dst: dst,
+ state: state,
+ }
+}
+
+func (w *Writer) writeChunk(p []byte, op C.BrotliEncoderOperation) (n int, err error) {
+ if w.state == nil {
+ return 0, errWriterClosed
+ }
+
+ for {
+ var data *C.uint8_t
+ if len(p) != 0 {
+ data = (*C.uint8_t)(&p[0])
+ }
+ result := C.CompressStream(w.state, op, data, C.size_t(len(p)))
+ if result.success == 0 {
+ return n, errEncode
+ }
+ p = p[int(result.bytes_consumed):]
+ n += int(result.bytes_consumed)
+
+ length := int(result.output_data_size)
+ if length != 0 {
+ // It is a workaround for non-copying-wrapping of native memory.
+ // C-encoder never pushes output block longer than ((2 << 25) + 502).
+ // TODO: use natural wrapper, when it becomes available, see
+ // https://golang.org/issue/13656.
+ output := (*[1 << 30]byte)(unsafe.Pointer(result.output_data))[:length:length]
+ _, err = w.dst.Write(output)
+ if err != nil {
+ return n, err
+ }
+ }
+ if len(p) == 0 && result.has_more == 0 {
+ return n, nil
+ }
+ }
+}
+
+// Flush outputs encoded data for all input provided to Write. The resulting
+// output can be decoded to match all input before Flush, but the stream is
+// not yet complete until after Close.
+// Flush has a negative impact on compression.
+func (w *Writer) Flush() error {
+ _, err := w.writeChunk(nil, C.BROTLI_OPERATION_FLUSH)
+ return err
+}
+
+// Close flushes remaining data to the decorated writer and frees C resources.
+func (w *Writer) Close() error {
+ // If stream is already closed, it is reported by `writeChunk`.
+ _, err := w.writeChunk(nil, C.BROTLI_OPERATION_FINISH)
+ // C-Brotli tolerates `nil` pointer here.
+ C.BrotliEncoderDestroyInstance(w.state)
+ w.state = nil
+ return err
+}
+
+// Write implements io.Writer. Flush or Close must be called to ensure that the
+// encoded bytes are actually flushed to the underlying Writer.
+func (w *Writer) Write(p []byte) (n int, err error) {
+ return w.writeChunk(p, C.BROTLI_OPERATION_PROCESS)
+}
+
+// Encode returns content encoded with Brotli.
+func Encode(content []byte, options WriterOptions) ([]byte, error) {
+ var buf bytes.Buffer
+ writer := NewWriter(&buf, options)
+ _, err := writer.Write(content)
+ if closeErr := writer.Close(); err == nil {
+ err = closeErr
+ }
+ return buf.Bytes(), err
+}
