base/posix/unix_domain_socket_linux.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_POSIX_UNIX_DOMAIN_SOCKET_LINUX_H_
   6 #define BASE_POSIX_UNIX_DOMAIN_SOCKET_LINUX_H_
   7
   8 #include <stdint.h>
   9 #include <sys/types.h>
  10 #include <vector>
  11
  12 #include "base/base_export.h"
  13
  14 class Pickle;
  15
  16 class BASE_EXPORT UnixDomainSocket {
  17  public:
  18   // Maximum number of file descriptors that can be read by RecvMsg().
  19   static const size_t kMaxFileDescriptors;
  20
  21   // Use sendmsg to write the given msg and include a vector of file
  22   // descriptors. Returns true if successful.
  23   static bool SendMsg(int fd,
  24                       const void* msg,
  25                       size_t length,
  26                       const std::vector<int>& fds);
  27
  28   // Use recvmsg to read a message and an array of file descriptors. Returns
  29   // -1 on failure. Note: will read, at most, |kMaxFileDescriptors| descriptors.
  30   static ssize_t RecvMsg(int fd,
  31                          void* msg,
  32                          size_t length,
  33                          std::vector<int>* fds);
  34
  35   // Perform a sendmsg/recvmsg pair.
  36   //   1. This process creates a UNIX SEQPACKET socketpair. Using
  37   //      connection-oriented sockets (SEQPACKET or STREAM) is critical here,
  38   //      because if one of the ends closes the other one must be notified.
  39   //   2. This process writes a request to |fd| with an SCM_RIGHTS control
  40   //      message containing on end of the fresh socket pair.
  41   //   3. This process blocks reading from the other end of the fresh
  42   //      socketpair.
  43   //   4. The target process receives the request, processes it and writes the
  44   //      reply to the end of the socketpair contained in the request.
  45   //   5. This process wakes up and continues.
  46   //
  47   //   fd: descriptor to send the request on
  48   //   reply: buffer for the reply
  49   //   reply_len: size of |reply|
  50   //   result_fd: (may be NULL) the file descriptor returned in the reply
  51   //              (if any)
  52   //   request: the bytes to send in the request
  53   static ssize_t SendRecvMsg(int fd,
  54                              uint8_t* reply,
  55                              unsigned reply_len,
  56                              int* result_fd,
  57                              const Pickle& request);
  58 };
  59
  60 #endif  // BASE_POSIX_UNIX_DOMAIN_SOCKET_LINUX_H_