[NaCl SDK] Support non blocking TCP/UDP

native_client_sdk/src/libraries/nacl_io/fifo_packet.cc

+// 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 "nacl_io/fifo_packet.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <algorithm>
+
+namespace nacl_io {
+
+FIFOPacket::FIFOPacket(size_t size)
+    : max_bytes_(size),
+      cur_bytes_(0) {}
+
+FIFOPacket::~FIFOPacket() {
+  while (!IsEmpty())
+    delete ReadPacket();
+}
+
+bool FIFOPacket::IsEmpty() {
+  return packets_.empty();
+}
+
+bool FIFOPacket::Resize(size_t len) {
+  max_bytes_ = len;
+  return true;
+}
+
+size_t FIFOPacket::ReadAvailable() {
+  return cur_bytes_;
+}
+
+size_t FIFOPacket::WriteAvailable() {
+  if (cur_bytes_ > max_bytes_)
+    return 0;
+
+  return max_bytes_ - cur_bytes_;
+}
+
+bool FIFOPacket::IsFull() {
+  return cur_bytes_ >= max_bytes_;
+}
+
+Packet* FIFOPacket::PeekPacket() {
+  if (packets_.empty())
+    return NULL;
+
+  return packets_.back();
+}
+
+Packet* FIFOPacket::ReadPacket() {
+  if (packets_.empty())
+    return NULL;
+
+  Packet* out = packets_.back();
+  packets_.pop_back();
+
+  cur_bytes_ -= out->buffer_.size();
+  return out;
+}
+
+void FIFOPacket::WritePacket(Packet* packet) {
+  cur_bytes_ += packet->buffer_.size();
+  packets_.push_front(packet);
+}
+
+}  // namespace nacl_io