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emacs/m4/getdtablesize.m4
Paul Eggert 846657afaf Update from Gnulib
This incorporates:
2020-08-16 time_rz: remove unused functions
2020-08-16 time_rz: fix issues with mktime_z failures
2020-08-16 nstrftime: Guide inlining also on clang
2020-08-16 intprops: Avoid bogus warning on clang
2020-08-16 libc-config: Enable __REDIRECT macro also on clang
2020-08-16 regex: Use initializer shorthand syntax also with clang
2020-08-16 regex: Use space optimization also with clang
2020-08-16 Use _Static_assert and static_assert when present on clang
2020-08-16 Use 'throw ()' for optimization in C++ mode also on clang
2020-08-16 stdio: Don't break attribute 'scanf' on clang
2020-08-16 Fix "warning: 'format' attribute ...: rpl_printf"
2020-08-16 Fix "warning: attribute declaration must precede definition"
2020-08-16 Fix undesired warnings
2020-08-16 Don't use Autoconf quadrigraphsxo
2020-08-16 Fix quoting of AC_LANG_PROGRAM arguments
2020-08-16 Assume autoconf >= 2.64
2020-08-15 nstrftime: be more predictable about errno
2020-08-15 canonicalize: Fix autoconf test on MSVC/clang
2020-08-15 Support compiling without -loldnames on native Windows
2020-08-14 mktime, mktime-internal: Remove obsolete code
2020-08-14 Assume tzset exists
* lib/c++defs.h, lib/canonicalize-lgpl.c, lib/cdefs.h, lib/dup2.c:
* lib/fcntl.in.h, lib/getopt-cdefs.in.h, lib/intprops.h, lib/md5.h:
* lib/mktime.c, lib/nstrftime.c, lib/open.c, lib/regcomp.c:
* lib/regex_internal.h, lib/stdio.in.h, lib/stdlib.in.h:
* lib/strftime.h, lib/string.in.h, lib/sys_select.in.h:
* lib/sys_stat.in.h, lib/sys_time.in.h, lib/time.in.h, lib/time_rz.c:
* lib/unistd.in.h, lib/verify.h, m4/00gnulib.m4:
* m4/absolute-header.m4, m4/alloca.m4, m4/canonicalize.m4, m4/dup2.m4:
* m4/fchmodat.m4, m4/fcntl.m4, m4/fdopendir.m4, m4/fpending.m4:
* m4/futimens.m4, m4/getdtablesize.m4, m4/getloadavg.m4:
* m4/gnulib-common.m4, m4/include_next.m4, m4/largefile.m4:
* m4/manywarnings.m4, m4/mktime.m4, m4/nstrftime.m4, m4/open-slash.m4:
* m4/pselect.m4, m4/pthread_sigmask.m4, m4/time_h.m4, m4/utimens.m4:
* m4/utimensat.m4, m4/utimes.m4, m4/warnings.m4:
Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.
2020-08-16 14:30:29 -07:00

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# getdtablesize.m4 serial 8
dnl Copyright (C) 2008-2020 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 $ac_cv_have_decl_getdtablesize = yes; then
AC_CACHE_CHECK([whether getdtablesize works],
[gl_cv_func_getdtablesize_works],
[dnl There are two concepts: the "maximum possible file descriptor value + 1"
dnl and the "maximum number of open file descriptors in a process".
dnl Per SUSv2 and POSIX, getdtablesize() should return the first one.
dnl On most platforms, the first and the second concept are the same.
dnl On OpenVMS, however, they are different and getdtablesize() returns
dnl the second one; thus the test below fails. But we don't care
dnl because there's no good way to write a replacement getdtablesize().
case "$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>]
GL_MDA_DEFINES
],
[[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
])
# Prerequisites of lib/getdtablesize.c.
AC_DEFUN([gl_PREREQ_GETDTABLESIZE], [:])