POSIX: Transfer network data using shared memory

chrome/common/descriptor_set_posix.cc

Index: chrome/common/descriptor_set_posix.cc
diff --git a/chrome/common/descriptor_set_posix.cc b/chrome/common/descriptor_set_posix.cc
new file mode 100644
index 0000000000000000000000000000000000000000..82f28997de5b8735a2a3a520a79d2956b4aa1621
--- /dev/null
+++ b/chrome/common/descriptor_set_posix.cc
@@ -0,0 +1,100 @@
+// Copyright (c) 2006-2008 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 "chrome/common/descriptor_set_posix.h"
+
+#include "base/logging.h"
+
+DescriptorSet::DescriptorSet()
+    : next_descriptor_(0) {
+}
+
+DescriptorSet::~DescriptorSet() {
+  if (next_descriptor_ == descriptors_.size())
+    return;
+
+  LOG(WARNING) << "DescriptorSet destroyed with unconsumed descriptors";
+  // We close all the descriptors where the close flag is set. If this
+  // message should have been transmitted, then closing those with close
+  // flags set mirrors the expected behaviour.
+  //
+  // If this message was received with more descriptors than expected
+  // (which could a DOS against the browser by a rouge renderer) then all
+  // the descriptors have their close flag set and we free all the extra
+  // kernel resources.
+  for (unsigned i = next_descriptor_; i < descriptors_.size(); ++i) {
+    if (descriptors_[i].auto_close)
+      close(descriptors_[i].fd);
+  }
+}
+
+bool DescriptorSet::Add(int fd) {
+  if (descriptors_.size() == MAX_DESCRIPTORS_PER_MESSAGE)
+    return false;
+
+  struct base::FileDescriptor sd;
+  sd.fd = fd;
+  sd.auto_close = false;
+  descriptors_.push_back(sd);
+  return true;
+}
+
+bool DescriptorSet::AddAndAutoClose(int fd) {
+  if (descriptors_.size() == MAX_DESCRIPTORS_PER_MESSAGE)
+    return false;
+
+  struct base::FileDescriptor sd;
+  sd.fd = fd;
+  sd.auto_close = true;
+  descriptors_.push_back(sd);
+  DCHECK(descriptors_.size() <= MAX_DESCRIPTORS_PER_MESSAGE);
+  return true;
+}
+
+int DescriptorSet::NextDescriptor() {
+  if (next_descriptor_ == descriptors_.size())
+    return -1;
+
+  return descriptors_[next_descriptor_++].fd;
+}
+
+void DescriptorSet::GetDescriptors(int* buffer) const {
+  DCHECK_EQ(next_descriptor_, 0u);
+
+  for (std::vector<base::FileDescriptor>::const_iterator
+       i = descriptors_.begin(); i != descriptors_.end(); ++i) {
+    *(buffer++) = i->fd;
+  }
+}
+
+void DescriptorSet::CommitAll() {
+  for (std::vector<base::FileDescriptor>::iterator
+       i = descriptors_.begin(); i != descriptors_.end(); ++i) {
+    if (i->auto_close)
+      close(i->fd);
+  }
+  descriptors_.clear();
+  next_descriptor_ = 0;
+}
+
+void DescriptorSet::SetDescriptors(const int* buffer, unsigned count) {
+  DCHECK(count <= MAX_DESCRIPTORS_PER_MESSAGE);
+  DCHECK(descriptors_.size() == 0);
+
+  descriptors_.reserve(count);
+  for (unsigned i = 0; i < count; ++i) {
+    struct base::FileDescriptor sd;
+    sd.fd = buffer[i];
+    sd.auto_close = true;
+    descriptors_.push_back(sd);
+  }
+}
+
+void DescriptorSet::TakeFrom(DescriptorSet* other) {
+  DCHECK(descriptors_.size() == 0);
+
+  descriptors_.swap(other->descriptors_);
+  next_descriptor_ = other->next_descriptor_;
+  other->next_descriptor_ = 0;
+}