# getdtablesize.m4 serial 6

dnl Copyright (C) 2008-2017 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_GETDTABLESIZE],

[

  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])

  AC_REQUIRE([AC_CANONICAL_HOST])

  AC_CHECK_FUNCS_ONCE([getdtablesize])

  AC_CHECK_DECLS_ONCE([getdtablesize])

  if test $ac_cv_func_getdtablesize = yes &&

     test $ac_cv_have_decl_getdtablesize = yes; then

    # Cygwin 1.7.25 automatically increases the RLIMIT_NOFILE soft limit

    # up to an unchangeable hard limit; all other platforms correctly

    # require setrlimit before getdtablesize() can report a larger value.

    AC_CACHE_CHECK([whether getdtablesize works],

      [gl_cv_func_getdtablesize_works],

      [AC_RUN_IFELSE([

        AC_LANG_PROGRAM([[#include <unistd.h>]],

          [int size = getdtablesize();

           if (dup2 (0, getdtablesize()) != -1)

             return 1;

           if (size != getdtablesize())

             return 2;

          ])],

        [gl_cv_func_getdtablesize_works=yes],

        [gl_cv_func_getdtablesize_works=no],

        [case "$host_os" in

          cygwin*) # on cygwin 1.5.25, getdtablesize() automatically grows

            gl_cv_func_getdtablesize_works="guessing no" ;;

          *) gl_cv_func_getdtablesize_works="guessing yes" ;;

         esac])

      ])

    case "$gl_cv_func_getdtablesize_works" in

      *yes) ;;

      *) REPLACE_GETDTABLESIZE=1 ;;

    esac

  else

    HAVE_GETDTABLESIZE=0

  fi

])

# Prerequisites of lib/getdtablesize.c.

AC_DEFUN([gl_PREREQ_GETDTABLESIZE], [:])