sysdeps/unix/sysv/linux/accept4.c

   1 /* Copyright (C) 2008-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2008.
   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 <signal.h>
  21 #include <sys/socket.h>
  22
  23 #include <sysdep-cancel.h>
  24 #include <sys/syscall.h>
  25 #include <kernel-features.h>
  26
  27 /* Do not use the accept4 syscall on socketcall architectures unless
  28    it was added at the same time as the socketcall support or can be
  29    assumed to be present.  */
  30 #if defined __ASSUME_SOCKETCALL \
  31     && !defined __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL \
  32     && !defined __ASSUME_ACCEPT4_SYSCALL
  33 # undef __NR_accept4
  34 #endif
  35
  36 #ifdef __NR_accept4
  37 int
  38 accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
  39 {
  40   return SYSCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len, flags);
  41 }
  42 #elif defined __NR_socketcall
  43 # include <socketcall.h>
  44 # ifdef __ASSUME_ACCEPT4_SOCKETCALL
  45 int
  46 accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
  47 {
  48   return SOCKETCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len, flags);
  49 }
  50 # else
  51 static int have_accept4;
  52
  53 int
  54 accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
  55 {
  56   if (__glibc_likely (have_accept4 >= 0))
  57     {
  58       int ret = SOCKETCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len,
  59                                    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_accept4 == 0
  64           && errno == EINVAL)
  65         {
  66           /* Try another call, this time with the FLAGS parameter
  67              cleared and an invalid file descriptor.  This call will not
  68              cause any harm and it will return immediately.  */
  69           ret = SOCKETCALL_CANCEL (invalid, -1);
  70           if (errno == EINVAL)
  71             {
  72               have_accept4 = -1;
  73               __set_errno (ENOSYS);
  74             }
  75           else
  76             {
  77               have_accept4 = 1;
  78               __set_errno (EINVAL);
  79             }
  80           return -1;
  81         }
  82       return ret;
  83     }
  84   __set_errno (ENOSYS);
  85   return -1;
  86 }
  87 # endif /* __ASSUME_ACCEPT4_SOCKETCALL  */
  88 #else /* __NR_socketcall   */
  89 int
  90 accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
  91 {
  92   __set_errno (ENOSYS);
  93   return -1;
  94 }
  95 stub_warning (accept4)
  96 #endif