+AC_CACHE_CHECK([for usable FIONREAD], [emacs_cv_usable_FIONREAD],
+ [case $opsys in
+ aix4-2)
+ dnl BUILD 9008 - FIONREAD problem still exists in X-Windows.
+ emacs_cv_usable_FIONREAD=no
+ ;;
+
+ *)
+ AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM([[#include <sys/types.h>
+ #include <sys/ioctl.h>
+ #ifdef USG5_4
+ # include <sys/filio.h>
+ #endif
+ ]],
+ [[int foo = ioctl (0, FIONREAD, &foo);]])],
+ [emacs_cv_usable_FIONREAD=yes],
+ [emacs_cv_usable_FIONREAD=no])
+ ;;
+ esac])
+if test $emacs_cv_usable_FIONREAD = yes; then
+ AC_DEFINE([USABLE_FIONREAD], [1], [Define to 1 if FIONREAD is usable.])
+
+ if test $emacs_broken_SIGIO = no; then
+ AC_CACHE_CHECK([for usable SIGIO], [emacs_cv_usable_SIGIO],
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM([[#include <fcntl.h>
+ #include <signal.h>
+ ]],
+ [[int foo = SIGIO | F_SETFL | FASYNC;]])],
+ [emacs_cv_usable_SIGIO=yes],
+ [emacs_cv_usable_SIGIO=no])],
+ [emacs_cv_usable_SIGIO=yes],
+ [emacs_cv_usable_SIGIO=no])
+ if test $emacs_cv_usable_SIGIO = yes; then
+ AC_DEFINE([USABLE_SIGIO], [1], [Define to 1 if SIGIO is usable.])
+ fi
+ fi
+fi
+