sysdeps/unix/sysv/linux/accept4.c

   1 /* Copyright (C) 2008-2015 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   if (SINGLE_THREAD_P)
  41     return INLINE_SYSCALL (accept4, 4, fd, addr.__sockaddr__, addr_len, flags);
  42
  43   int oldtype = LIBC_CANCEL_ASYNC ();
  44
  45   int result = INLINE_SYSCALL (accept4, 4, fd, addr.__sockaddr__, addr_len,
  46                                flags);
  47
  48   LIBC_CANCEL_RESET (oldtype);
  49
  50   return result;
  51 }
  52 #elif defined __NR_socketcall
  53 # ifndef __ASSUME_ACCEPT4_SOCKETCALL
  54 extern int __internal_accept4 (int fd, __SOCKADDR_ARG addr,
  55                                socklen_t *addr_len, int flags)
  56      attribute_hidden;
  57
  58 static int have_accept4;
  59
  60 int
  61 accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
  62 {
  63   if (__glibc_likely (have_accept4 >= 0))
  64     {
  65       int ret = __internal_accept4 (fd, addr, addr_len, 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_accept4 == 0
  70           && errno == EINVAL)
  71         {
  72           /* Try another call, this time with the FLAGS parameter
  73              cleared and an invalid file descriptor.  This call will not
  74              cause any harm and it will return immediately.  */
  75           ret = __internal_accept4 (-1, addr, addr_len, 0);
  76           if (errno == EINVAL)
  77             {
  78               have_accept4 = -1;
  79               __set_errno (ENOSYS);
  80             }
  81           else
  82             {
  83               have_accept4 = 1;
  84               __set_errno (EINVAL);
  85             }
  86           return -1;
  87         }
  88       return ret;
  89     }
  90   __set_errno (ENOSYS);
  91   return -1;
  92 }
  93 # else
  94 /* When __ASSUME_ACCEPT4_SOCKETCALL accept4 is defined in
  95    internal_accept4.S.  */
  96 # endif
  97 #else
  98 int
  99 accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
 100 {
 101   __set_errno (ENOSYS);
 102   return -1;
 103 }
 104 stub_warning (accept4)
 105 #endif