# poll.m4 serial 18

dnl Copyright (c) 2003, 2005-2007, 2009-2018 Free Software Foundation, Inc.

dnl This file is free software; the Free Software Foundation

dnl gives unlimited permission to copy and/or distribute it,

dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_POLL],

[

  AC_REQUIRE([gl_POLL_H])

  AC_REQUIRE([gl_SOCKETS])

  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  if test $ac_cv_header_poll_h = no; then

    ac_cv_func_poll=no

    gl_cv_func_poll=no

  else

    AC_CHECK_FUNC([poll],

      [# Check whether poll() works on special files (like /dev/null) and

       # and ttys (like /dev/tty). On Mac OS X 10.4.0 and AIX 5.3, it doesn't.

       AC_RUN_IFELSE([AC_LANG_SOURCE([[

#include <fcntl.h>

#include <poll.h>

         int main()

         {

           int result = 0;

           struct pollfd ufd;

           /* Try /dev/null for reading.  */

           ufd.fd = open ("/dev/null", O_RDONLY);

           /* If /dev/null does not exist, it's not Mac OS X nor AIX. */

           if (ufd.fd >= 0)

             {

               ufd.events = POLLIN;

               ufd.revents = 0;

               if (!(poll (&ufd, 1, 0) == 1 && ufd.revents == POLLIN))

                 result |= 1;

             }

           /* Try /dev/null for writing.  */

           ufd.fd = open ("/dev/null", O_WRONLY);

           /* If /dev/null does not exist, it's not Mac OS X nor AIX. */

           if (ufd.fd >= 0)

             {

               ufd.events = POLLOUT;

               ufd.revents = 0;

               if (!(poll (&ufd, 1, 0) == 1 && ufd.revents == POLLOUT))

                 result |= 2;

             }

           /* Trying /dev/tty may be too environment dependent.  */

           return result;

         }]])],

         [gl_cv_func_poll=yes],

         [gl_cv_func_poll=no],

         [# When cross-compiling, assume that poll() works everywhere except on

          # Mac OS X or AIX, regardless of its version.

          AC_EGREP_CPP([MacOSX], [

#if (defined(__APPLE__) && defined(__MACH__)) || defined(_AIX)

This is MacOSX or AIX

#endif

], [gl_cv_func_poll=no], [gl_cv_func_poll=yes])])])

  fi

  if test $gl_cv_func_poll != yes; then

    AC_CHECK_FUNC([poll], [ac_cv_func_poll=yes], [ac_cv_func_poll=no])

    if test $ac_cv_func_poll = no; then

      HAVE_POLL=0

    else

      REPLACE_POLL=1

    fi

  fi

  if test $HAVE_POLL = 0 || test $REPLACE_POLL = 1; then

    :

  else

    AC_DEFINE([HAVE_POLL], [1],

      [Define to 1 if you have the 'poll' function and it works.])

  fi

  dnl Determine the needed libraries.

  LIB_POLL="$LIBSOCKET"

  if test $HAVE_POLL = 0 || test $REPLACE_POLL = 1; then

    case "$host_os" in

      mingw*)

        dnl On the MSVC platform, the function MsgWaitForMultipleObjects

        dnl (used in lib/poll.c) requires linking with -luser32. On mingw,

        dnl it is implicit.

        AC_LINK_IFELSE(

          [AC_LANG_SOURCE([[

#define WIN32_LEAN_AND_MEAN

#include <windows.h>

int

main ()

{

  MsgWaitForMultipleObjects (0, NULL, 0, 0, 0);

  return 0;

}]])],

          [],

          [LIB_POLL="$LIB_POLL -luser32"])

        ;;

    esac

  fi

  AC_SUBST([LIB_POLL])

])

# Prerequisites of lib/poll.c.

AC_DEFUN([gl_PREREQ_POLL],

[

  AC_CHECK_HEADERS_ONCE([sys/ioctl.h sys/filio.h])

])