-# getdtablesize.m4 serial 4
-dnl Copyright (C) 2008-2013 Free Software Foundation, Inc.
+# getdtablesize.m4 serial 7
+dnl Copyright (C) 2008-2018 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])
- if test $ac_cv_func_getdtablesize != yes; then
+ AC_CHECK_DECLS_ONCE([getdtablesize])
+ if test $ac_cv_func_getdtablesize = yes &&
+ test $ac_cv_have_decl_getdtablesize = yes; then
+ AC_CACHE_CHECK([whether getdtablesize works],
+ [gl_cv_func_getdtablesize_works],
+ [dnl There are two concepts: the "maximum possible file descriptor value + 1"
+ dnl and the "maximum number of open file descriptors in a process".
+ dnl Per SUSv2 and POSIX, getdtablesize() should return the first one.
+ dnl On most platforms, the first and the second concept are the same.
+ dnl On OpenVMS, however, they are different and getdtablesize() returns
+ dnl the second one; thus the test below fails. But we don't care
+ dnl because there's no good way to write a replacement getdtablesize().
+ case "$host_os" in
+ vms*) gl_cv_func_getdtablesize_works="no (limitation)" ;;
+ *)
+ dnl Cygwin 1.7.25 automatically increases the RLIMIT_NOFILE soft
+ dnl limit up to an unchangeable hard limit; all other platforms
+ dnl correctly require setrlimit before getdtablesize() can report
+ dnl a larger value.
+ 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 "$host_os" in
+ cygwin*) # on cygwin 1.5.25, getdtablesize() automatically grows
+ gl_cv_func_getdtablesize_works="guessing no" ;;
+ *) gl_cv_func_getdtablesize_works="guessing yes" ;;
+ esac
+ ])
+ ;;
+ esac
+ ])
+ case "$gl_cv_func_getdtablesize_works" in
+ *yes | "no (limitation)") ;;
+ *) REPLACE_GETDTABLESIZE=1 ;;
+ esac
+ else
HAVE_GETDTABLESIZE=0
fi
])