Implement WebSocketDeflater.

net/websockets/websocket_deflater.cc

Index: net/websockets/websocket_deflater.cc
diff --git a/net/websockets/websocket_deflater.cc b/net/websockets/websocket_deflater.cc
new file mode 100644
index 0000000000000000000000000000000000000000..779db1504c97c667cabf6dd2b5f503382992e93d
--- /dev/null
+++ b/net/websockets/websocket_deflater.cc
@@ -0,0 +1,118 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/websockets/websocket_deflater.h"
+
+#include <string.h>
+#include <vector>
+
+#include "base/logging.h"
+#include "net/base/io_buffer.h"
+#include "third_party/zlib/zlib.h"
+
+namespace net {
+
+WebSocketDeflater::WebSocketDeflater(int window_bits,
+                                     ContextTakeOverMode mode)
+    : stream_(new z_stream)

[Adam Rice, 2013/08/29 12:04:33]

The commas go after the initialiser in Chromium style. clang-format should fix
this for you.

[yhirano, 2013/08/30 06:20:35]

Done.

+    , mode_(mode)
+    , are_bytes_added_(false) {
+  DCHECK_LE(8, window_bits);
+  DCHECK_GE(15, window_bits);
+  memset(stream_.get(), 0, sizeof(*stream_));
+  int result = deflateInit2(stream_.get(),
+                            Z_DEFAULT_COMPRESSION,
+                            Z_DEFLATED,
+                            -window_bits,
+                            8,  // default mem level
+                            Z_DEFAULT_STRATEGY);
+  DCHECK_EQ(Z_OK, result);
+}
+
+WebSocketDeflater::~WebSocketDeflater() {
+  if (stream_) {
+    deflateEnd(stream_.get());
+    stream_.reset(nullptr);

[Adam Rice, 2013/08/29 12:04:33]

I'm not sure why "nullptr" compiles. The compiler should be in C++03 mode and  I
can't find an implementation in src/base. Anyway, stream_.reset() is sufficient,
but it is probably better just to leave it to the scoped_ptr destructor.

[yhirano, 2013/08/30 06:20:35]

Done.

+  }
+}
+
+bool WebSocketDeflater::AddBytes(const char* data, size_t size) {
+  if (!size) {

[Adam Rice, 2013/08/29 12:04:33]

Chromium net people seem to prefer no { } for if statements like this.

[yhirano, 2013/08/30 06:20:35]

Done.

+    return true;
+  }
+
+  stream_->next_in = reinterpret_cast<Bytef*>(const_cast<char*>(data));
+  stream_->avail_in = size;
+
+  // The estimation by deflateBound is not accurate if the zlib has some
+  // remaining input of the last compression.
+  size_t estimation = deflateBound(stream_.get(), size);
+  DCHECK_GT(estimation, 0u);
+  do {
+    size_t current = buffer_.size();
+    buffer_.resize(buffer_.size() + estimation);

[Adam Rice, 2013/08/29 12:04:33]

This is slightly suboptimal since the vector will fill the extra space with
'\0'. I haven't got any good proposal to solve it, but you might have a good
idea or perhaps you could add a TODO mentioning the issue.

[yhirano, 2013/08/30 06:20:35]

Done.

+    stream_->next_out = reinterpret_cast<Bytef*>(&buffer_[current]);
+    stream_->avail_out = buffer_.size() - current;
+
+    int result = deflate(stream_.get(), Z_NO_FLUSH);
+    if (result != Z_OK) {
+      return false;
+    }
+    buffer_.resize(buffer_.size() - stream_->avail_out);
+    estimation *= 2;
+  } while (!stream_->avail_out);
+  are_bytes_added_ = true;
+
+  return true;
+}
+
+scoped_refptr<IOBufferWithSize> WebSocketDeflater::Finish() {
+  scoped_refptr<IOBufferWithSize> result;
+  if (!are_bytes_added_) {
+    // Since consecutive calls of deflate with Z_SYNC_FLUSH and
+    // no input lead to an error, we create and return the output
+    // for the empty input manually.
+    DCHECK(buffer_.empty());
+    result = new IOBufferWithSize(2);
+    memcpy(result->data(), "\x02\x00", result->size());
+    Reset();
+    return result;
+  }
+  stream_->next_in = nullptr;

[Adam Rice, 2013/08/29 12:04:33]

NULL in Chromium code. Also 2 other places below.

[yhirano, 2013/08/30 06:20:35]

Done.

+  stream_->avail_in = 0;
+
+  const size_t available_size = 4096;
+  do {
+    size_t current = buffer_.size();
+    buffer_.resize(buffer_.size() + available_size);
+    stream_->next_out = reinterpret_cast<Bytef*>(&buffer_[current]);
+    stream_->avail_out = buffer_.size() - current;
+
+    int result = deflate(stream_.get(), Z_SYNC_FLUSH);
+    buffer_.resize(buffer_.size() - stream_->avail_out);
+    if (result != Z_OK && result != Z_BUF_ERROR) {
+      Reset();
+      return nullptr;
+    }
+  } while (!stream_->avail_out);
+  // Remove 4 octets from the tail as the specification requires.
+  if (buffer_.size() < 4) {
+    Reset();
+    return nullptr;
+  }
+  result = new IOBufferWithSize(buffer_.size() - 4);
+  memcpy(result->data(), buffer_.data(), result->size());
+  Reset();
+  return result;
+}
+
+void WebSocketDeflater::Reset() {
+  buffer_.clear();
+  if (mode_ == DO_NOT_TAKE_OVER_CONTEXT) {
+    deflateReset(stream_.get());
+  }
+  are_bytes_added_ = false;
+}
+
+}  // namespace net