2 dnl Copyright (c) 2003, 2005 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 AC_DEFUN([gl_FUNC_POLL],
9 AC_CHECK_HEADERS(poll.h)
10 if test "$ac_cv_header_poll_h" = no; then
18 [# Check whether poll() works on special files (like /dev/null) and
19 # and ttys (like /dev/tty). On MacOS X 10.4.0, it doesn't.
26 /* Try /dev/null for reading. */
27 ufd.fd = open ("/dev/null", O_RDONLY);
28 if (ufd.fd < 0) /* If /dev/null does not exist, it's not MacOS X. */
32 if (!(poll (&ufd, 1, 0) == 1 && ufd.revents == POLLIN))
34 /* Try /dev/null for writing. */
35 ufd.fd = open ("/dev/null", O_WRONLY);
36 if (ufd.fd < 0) /* If /dev/null does not exist, it's not MacOS X. */
40 if (!(poll (&ufd, 1, 0) == 1 && ufd.revents == POLLOUT))
42 /* Trying /dev/tty may be too environment dependent. */
45 [gl_cv_func_poll=yes],
47 [# When cross-compiling, assume that poll() works everywhere except on
48 # MacOS X, regardless of its version.
49 AC_EGREP_CPP([MacOSX], [
50 #if defined(__APPLE__) && defined(__MACH__)
53 ], [gl_cv_func_poll=no], [gl_cv_func_poll=yes])])])
54 if test $gl_cv_func_poll = yes; then
55 AC_DEFINE([HAVE_POLL], 1,
56 [Define to 1 if you have the 'poll' function and it works.])
59 if test $gl_cv_func_poll = no; then
61 AC_DEFINE(poll, rpl_poll,
62 [Define to poll if the replacement function should be used.])
67 # Prerequisites of lib/poll.c.
68 AC_DEFUN([gl_PREREQ_POLL],
70 AC_REQUIRE([AC_HEADER_TIME])
71 AC_CHECK_HEADERS_ONCE(sys/time.h)