+ 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 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 MacOS 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 MacOS 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
+ # MacOS 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])])])