Separates ipc code from common (http://crbug.com/16829)

chrome/common/file_descriptor_set_posix.cc

-// 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/file_descriptor_set_posix.h"
-
-#include "base/eintr_wrapper.h"
-#include "base/logging.h"
-
-FileDescriptorSet::FileDescriptorSet()
-    : consumed_descriptor_highwater_(0) {
-}
-
-FileDescriptorSet::~FileDescriptorSet() {
-  if (consumed_descriptor_highwater_ == descriptors_.size())
-    return;
-
-  LOG(WARNING) << "FileDescriptorSet 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 rogue renderer) then all
-  // the descriptors have their close flag set and we free all the extra
-  // kernel resources.
-  for (unsigned i = consumed_descriptor_highwater_;
-       i < descriptors_.size(); ++i) {
-    if (descriptors_[i].auto_close)
-      HANDLE_EINTR(close(descriptors_[i].fd));
-  }
-}
-
-bool FileDescriptorSet::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 FileDescriptorSet::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 FileDescriptorSet::GetDescriptorAt(unsigned index) const {
-  if (index >= descriptors_.size())
-    return -1;
-
-  // We should always walk the descriptors in order, so it's reasonable to
-  // enforce this. Consider the case where a compromised renderer sends us
-  // the following message:
-  //
-  //   ExampleMsg:
-  //     num_fds:2 msg:FD(index = 1) control:SCM_RIGHTS {n, m}
-  //
-  // Here the renderer sent us a message which should have a descriptor, but
-  // actually sent two in an attempt to fill our fd table and kill us. By
-  // setting the index of the descriptor in the message to 1 (it should be
-  // 0), we would record a highwater of 1 and then consider all the
-  // descriptors to have been used.
-  //
-  // So we can either track of the use of each descriptor in a bitset, or we
-  // can enforce that we walk the indexes strictly in order.
-  //
-  // There's one more wrinkle: When logging messages, we may reparse them. So
-  // we have an exception: When the consumed_descriptor_highwater_ is at the
-  // end of the array and index 0 is requested, we reset the highwater value.
-  if (index == 0 && consumed_descriptor_highwater_ == descriptors_.size())
-    consumed_descriptor_highwater_ = 0;
-
-  if (index != consumed_descriptor_highwater_)
-    return -1;
-
-  consumed_descriptor_highwater_ = index + 1;
-  return descriptors_[index].fd;
-}
-
-void FileDescriptorSet::GetDescriptors(int* buffer) const {
-  for (std::vector<base::FileDescriptor>::const_iterator
-       i = descriptors_.begin(); i != descriptors_.end(); ++i) {
-    *(buffer++) = i->fd;
-  }
-}
-
-void FileDescriptorSet::CommitAll() {
-  for (std::vector<base::FileDescriptor>::iterator
-       i = descriptors_.begin(); i != descriptors_.end(); ++i) {
-    if (i->auto_close)
-      HANDLE_EINTR(close(i->fd));
-  }
-  descriptors_.clear();
-  consumed_descriptor_highwater_ = 0;
-}
-
-void FileDescriptorSet::SetDescriptors(const int* buffer, unsigned count) {
-  DCHECK_LE(count, MAX_DESCRIPTORS_PER_MESSAGE);
-  DCHECK_EQ(descriptors_.size(), 0u);
-  DCHECK_EQ(consumed_descriptor_highwater_, 0u);
-
-  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);
-  }
-}