sysdeps/unix/sysv/linux/sendmmsg.c

   1 /* Copyright (C) 2011-2016 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   return SYSCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
  40 }
  41 libc_hidden_def (__sendmmsg)
  42 weak_alias (__sendmmsg, sendmmsg)
  43 #elif defined __NR_socketcall
  44 # include <socketcall.h>
  45 # ifdef __ASSUME_SENDMMSG_SOCKETCALL
  46 int
  47 __sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
  48 {
  49   return SOCKETCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
  50 }
  51 # else
  52 static int have_sendmmsg;
  53
  54 int
  55 __sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
  56 {
  57   if (__glibc_likely (have_sendmmsg >= 0))
  58     {
  59       int ret = SOCKETCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
  60       /* The kernel returns -EINVAL for unknown socket operations.
  61          We need to convert that error to an ENOSYS error.  */
  62       if (__builtin_expect (ret < 0, 0)
  63           && have_sendmmsg == 0
  64           && errno == EINVAL)
  65         {
  66           /* Try another call, this time with an invalid file
  67              descriptor and all other parameters cleared.  This call
  68              will not cause any harm and it will return
  69              immediately.  */
  70           ret = SOCKETCALL_CANCEL (invalid, -1);
  71           if (errno == EINVAL)
  72             {
  73               have_sendmmsg = -1;
  74               __set_errno (ENOSYS);
  75             }
  76           else
  77             {
  78               have_sendmmsg = 1;
  79               __set_errno (EINVAL);
  80             }
  81           return -1;
  82         }
  83       return ret;
  84     }
  85   __set_errno (ENOSYS);
  86   return -1;
  87 }
  88 # endif /* __ASSUME_SENDMMSG_SOCKETCALL  */
  89 libc_hidden_def (__sendmmsg)
  90 weak_alias (__sendmmsg, sendmmsg)
  91 #else
  92 # include <socket/sendmmsg.c>
  93 #endif