sysdeps/unix/sysv/linux/sendmmsg.c

   1 /* Copyright (C) 2011-2015 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <sys/socket.h>
  21
  22 #include <sysdep-cancel.h>
  23 #include <sys/syscall.h>
  24 #include <kernel-features.h>
  25
  26 /* Do not use the sendmmsg syscall on socketcall architectures unless
  27    it was added at the same time as the socketcall support or can be
  28    assumed to be present.  */
  29 #if defined __ASSUME_SOCKETCALL \
  30     && !defined __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL \
  31     && !defined __ASSUME_SENDMMSG_SYSCALL
  32 # undef __NR_sendmmsg
  33 #endif
  34
  35 #ifdef __NR_sendmmsg
  36 int
  37 __sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
  38 {
  39   if (SINGLE_THREAD_P)
  40     return INLINE_SYSCALL (sendmmsg, 4, fd, vmessages, vlen, flags);
  41
  42   int oldtype = LIBC_CANCEL_ASYNC ();
  43
  44   int result = INLINE_SYSCALL (sendmmsg, 4, fd, vmessages, vlen, flags);
  45
  46   LIBC_CANCEL_RESET (oldtype);
  47
  48   return result;
  49 }
  50 libc_hidden_def (__sendmmsg)
  51 weak_alias (__sendmmsg, sendmmsg)
  52 #elif defined __NR_socketcall
  53 # ifndef __ASSUME_SENDMMSG_SOCKETCALL
  54 extern int __internal_sendmmsg (int fd, struct mmsghdr *vmessages,
  55                                 unsigned int vlen, int flags)
  56      attribute_hidden;
  57
  58 static int have_sendmmsg;
  59
  60 int
  61 __sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
  62 {
  63   if (__glibc_likely (have_sendmmsg >= 0))
  64     {
  65       int ret = __internal_sendmmsg (fd, vmessages, vlen, flags);
  66       /* The kernel returns -EINVAL for unknown socket operations.
  67          We need to convert that error to an ENOSYS error.  */
  68       if (__builtin_expect (ret < 0, 0)
  69           && have_sendmmsg == 0
  70           && errno == EINVAL)
  71         {
  72           /* Try another call, this time with an invalid file
  73              descriptor and all other parameters cleared.  This call
  74              will not cause any harm and it will return
  75              immediately.  */
  76           ret = __internal_sendmmsg (-1, 0, 0, 0);
  77           if (errno == EINVAL)
  78             {
  79               have_sendmmsg = -1;
  80               __set_errno (ENOSYS);
  81             }
  82           else
  83             {
  84               have_sendmmsg = 1;
  85               __set_errno (EINVAL);
  86             }
  87           return -1;
  88         }
  89       return ret;
  90     }
  91   __set_errno (ENOSYS);
  92   return -1;
  93 }
  94 libc_hidden_def (__sendmmsg)
  95 weak_alias (__sendmmsg, sendmmsg)
  96 # else
  97 /* When __ASSUME_SENDMMSG_SOCKETCALL sendmmsg is defined in
  98    internal_sendmmsg.S.  */
  99 # endif
 100 #else
 101 # include <socket/sendmmsg.c>
 102 #endif