sysdeps/unix/sysv/linux/recvmsg.c

   1 /* Copyright (C) 2015-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <sys/socket.h>
  19 #include <sysdep-cancel.h>
  20 #include <socketcall.h>
  21 #include <shlib-compat.h>
  22
  23 ssize_t
  24 __libc_recvmsg (int fd, struct msghdr *msg, int flags)
  25 {
  26   ssize_t ret;
  27
  28   /* POSIX specifies that both msghdr::msg_iovlen and msghdr::msg_controllen
  29      to be int and socklen_t respectively.  However Linux defines it as
  30      both size_t.  So for 64-bit it requires some adjustments by copying to
  31      temporary header and zeroing the pad fields.  */
  32 #if __WORDSIZE == 64
  33   struct msghdr hdr, *orig = msg;
  34   if (msg != NULL)
  35     {
  36       hdr = *msg;
  37       hdr.__glibc_reserved1 = 0;
  38       hdr.__glibc_reserved2 = 0;
  39       msg = &hdr;
  40     }
  41 #endif
  42
  43 #ifdef __ASSUME_RECVMSG_SYSCALL
  44   ret = SYSCALL_CANCEL (recvmsg, fd, msg, flags);
  45 #else
  46   ret = SOCKETCALL_CANCEL (recvmsg, fd, msg, flags);
  47 #endif
  48
  49 #if __WORDSIZE == 64
  50   if (orig != NULL)
  51     *orig = hdr;
  52 #endif
  53
  54   return ret;
  55 }
  56 weak_alias (__libc_recvmsg, __recvmsg)
  57 versioned_symbol (libc, __libc_recvmsg, recvmsg, GLIBC_2_24);