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

chrome/common/file_descriptor_set_posix.h

-// Copyright (c) 2006-2009 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.
-
-#ifndef CHROME_COMMON_FILE_DESCRIPTOR_SET_POSIX_H_
-#define CHROME_COMMON_FILE_DESCRIPTOR_SET_POSIX_H_
-
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/file_descriptor_posix.h"
-#include "base/ref_counted.h"
-
-// -----------------------------------------------------------------------------
-// A FileDescriptorSet is an ordered set of POSIX file descriptors. These are
-// associated with IPC messages so that descriptors can be transmitted over a
-// UNIX domain socket.
-// -----------------------------------------------------------------------------
-class FileDescriptorSet : public base::RefCountedThreadSafe<FileDescriptorSet> {
- public:
-  FileDescriptorSet();
-  ~FileDescriptorSet();
-
-  // This is the maximum number of descriptors per message. We need to know this
-  // because the control message kernel interface has to be given a buffer which
-  // is large enough to store all the descriptor numbers. Otherwise the kernel
-  // tells us that it truncated the control data and the extra descriptors are
-  // lost.
-  //
-  // In debugging mode, it's a fatal error to try and add more than this number
-  // of descriptors to a FileDescriptorSet.
-  enum {
-    MAX_DESCRIPTORS_PER_MESSAGE = 4,
-  };
-
-  // ---------------------------------------------------------------------------
-  // Interfaces for building during message serialisation...
-
-  // Add a descriptor to the end of the set. Returns false iff the set is full.
-  bool Add(int fd);
-  // Add a descriptor to the end of the set and automatically close it after
-  // transmission. Returns false iff the set is full.
-  bool AddAndAutoClose(int fd);
-
-  // ---------------------------------------------------------------------------
-
-
-  // ---------------------------------------------------------------------------
-  // Interfaces for accessing during message deserialisation...
-
-  // Return the number of descriptors
-  unsigned size() const { return descriptors_.size(); }
-  // Return true if no unconsumed descriptors remain
-  bool empty() const { return descriptors_.empty(); }
-  // Fetch the nth descriptor from the beginning of the set. Code using this
-  // /must/ access the descriptors in order, except that it may wrap from the
-  // end to index 0 again.
-  //
-  // This interface is designed for the deserialising code as it doesn't
-  // support close flags.
-  //   returns: file descriptor, or -1 on error
-  int GetDescriptorAt(unsigned n) const;
-
-  // ---------------------------------------------------------------------------
-
-
-  // ---------------------------------------------------------------------------
-  // Interfaces for transmission...
-
-  // Fill an array with file descriptors without 'consuming' them. CommitAll
-  // must be called after these descriptors have been transmitted.
-  //   buffer: (output) a buffer of, at least, size() integers.
-  void GetDescriptors(int* buffer) const;
-  // This must be called after transmitting the descriptors returned by
-  // GetDescriptors. It marks all the descriptors as consumed and closes those
-  // which are auto-close.
-  void CommitAll();
-
-  // ---------------------------------------------------------------------------
-
-
-  // ---------------------------------------------------------------------------
-  // Interfaces for receiving...
-
-  // Set the contents of the set from the given buffer. This set must be empty
-  // before calling. The auto-close flag is set on all the descriptors so that
-  // unconsumed descriptors are closed on destruction.
-  void SetDescriptors(const int* buffer, unsigned count);
-
-  // ---------------------------------------------------------------------------
-
- private:
-  // A vector of descriptors and close flags. If this message is sent, then
-  // these descriptors are sent as control data. After sending, any descriptors
-  // with a true flag are closed. If this message has been received, then these
-  // are the descriptors which were received and all close flags are true.
-  std::vector<base::FileDescriptor> descriptors_;
-
-  // This contains the index of the next descriptor which should be consumed.
-  // It's used in a couple of ways. Firstly, at destruction we can check that
-  // all the descriptors have been read (with GetNthDescriptor). Secondly, we
-  // can check that they are read in order.
-  mutable unsigned consumed_descriptor_highwater_;
-
-  DISALLOW_COPY_AND_ASSIGN(FileDescriptorSet);
-};
-
-#endif  // CHROME_COMMON_FILE_DESCRIPTOR_SET_POSIX_H_