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