.

[gnulib.git] / m4 / poll.m4

diff --git a/m4/poll.m4 b/m4/poll.m4
index 5bfc33c..aed57a0 100644 (file)
--- a/m4/poll.m4
+++ b/m4/poll.m4
@@ -1,10 +1,8 @@
-# poll.m4 serial 2
-dnl Copyright (c) 2003 Free Software Foundation, Inc.
-dnl This file is free software, distributed under the terms of the GNU
-dnl General Public License.  As a special exception to the GNU General
-dnl Public License, this file may be distributed as part of a program
-dnl that contains a configuration script generated by Autoconf, under
-dnl the same distribution terms as the rest of the program.
+# poll.m4 serial 4
+dnl Copyright (c) 2003, 2005 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],
 [
@@ -16,8 +14,52 @@ AC_DEFUN([gl_FUNC_POLL],
   fi
   AC_SUBST([POLL_H])
 
-  AC_REPLACE_FUNCS(poll)
-  if test $ac_cv_func_poll = no; then
+  AC_CHECK_FUNC(poll,
+    [# Check whether poll() works on special files (like /dev/null) and
+     # and ttys (like /dev/tty). On MacOS X 10.4.0, it doesn't.
+     AC_TRY_RUN([
+#include <fcntl.h>
+#include <poll.h>
+       int main()
+       {
+         struct pollfd ufd;
+         /* Try /dev/null for reading.  */
+         ufd.fd = open ("/dev/null", O_RDONLY);
+         if (ufd.fd < 0) /* If /dev/null does not exist, it's not MacOS X. */
+           return 0;
+         ufd.events = POLLIN;
+         ufd.revents = 0;
+         if (!(poll (&ufd, 1, 0) == 1 && ufd.revents == POLLIN))
+           return 1;
+         /* Try /dev/null for writing.  */
+         ufd.fd = open ("/dev/null", O_WRONLY);
+         if (ufd.fd < 0) /* If /dev/null does not exist, it's not MacOS X. */
+           return 0;
+         ufd.events = POLLOUT;
+         ufd.revents = 0;
+         if (!(poll (&ufd, 1, 0) == 1 && ufd.revents == POLLOUT))
+           return 1;
+         /* Trying /dev/tty may be too environment dependent.  */
+         return 0;
+       }],
+       [gl_cv_func_poll=yes],
+       [gl_cv_func_poll=no],
+       [# When cross-compiling, assume that poll() works everywhere except on
+        # MacOS X, regardless of its version.
+        AC_EGREP_CPP([MacOSX], [
+#if defined(__APPLE__) && defined(__MACH__)
+This is MacOSX
+#endif
+], [gl_cv_func_poll=no], [gl_cv_func_poll=yes])])])
+  if test $gl_cv_func_poll = yes; then
+    AC_DEFINE([HAVE_POLL], 1,
+      [Define to 1 if you have the 'poll' function and it works.])
+  fi
+
+  if test $gl_cv_func_poll = no; then
+    AC_LIBOBJ(poll)
+    AC_DEFINE(poll, rpl_poll,
+      [Define to poll if the replacement function should be used.])
     gl_PREREQ_POLL
   fi
 ])