| 1 | # getdtablesize.m4 serial 8
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| 2 | dnl Copyright (C) 2008-2022 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | AC_DEFUN([gl_FUNC_GETDTABLESIZE],
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| 8 | [
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| 9 | AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
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| 10 | AC_REQUIRE([AC_CANONICAL_HOST])
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| 11 | AC_CHECK_FUNCS_ONCE([getdtablesize])
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| 12 | AC_CHECK_DECLS_ONCE([getdtablesize])
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| 13 | if test $ac_cv_func_getdtablesize = yes &&
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| 14 | test $ac_cv_have_decl_getdtablesize = yes; then
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| 15 | AC_CACHE_CHECK([whether getdtablesize works],
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| 16 | [gl_cv_func_getdtablesize_works],
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| 17 | [dnl There are two concepts: the "maximum possible file descriptor value + 1"
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| 18 | dnl and the "maximum number of open file descriptors in a process".
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| 19 | dnl Per SUSv2 and POSIX, getdtablesize() should return the first one.
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| 20 | dnl On most platforms, the first and the second concept are the same.
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| 21 | dnl On OpenVMS, however, they are different and getdtablesize() returns
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| 22 | dnl the second one; thus the test below fails. But we don't care
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| 23 | dnl because there's no good way to write a replacement getdtablesize().
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| 24 | case "$host_os" in
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| 25 | vms*) gl_cv_func_getdtablesize_works="no (limitation)" ;;
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| 26 | *)
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| 27 | dnl Cygwin 1.7.25 automatically increases the RLIMIT_NOFILE soft
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| 28 | dnl limit up to an unchangeable hard limit; all other platforms
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| 29 | dnl correctly require setrlimit before getdtablesize() can report
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| 30 | dnl a larger value.
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| 31 | AC_RUN_IFELSE([
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| 32 | AC_LANG_PROGRAM(
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| 33 | [[#include <unistd.h>]
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| 34 | GL_MDA_DEFINES
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| 35 | ],
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| 36 | [[int size = getdtablesize();
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| 37 | if (dup2 (0, getdtablesize()) != -1)
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| 38 | return 1;
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| 39 | if (size != getdtablesize())
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| 40 | return 2;
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| 41 | ]])],
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| 42 | [gl_cv_func_getdtablesize_works=yes],
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| 43 | [gl_cv_func_getdtablesize_works=no],
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| 44 | [case "$host_os" in
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| 45 | cygwin*) # on cygwin 1.5.25, getdtablesize() automatically grows
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| 46 | gl_cv_func_getdtablesize_works="guessing no" ;;
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| 47 | *) gl_cv_func_getdtablesize_works="guessing yes" ;;
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| 48 | esac
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| 49 | ])
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| 50 | ;;
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| 51 | esac
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| 52 | ])
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| 53 | case "$gl_cv_func_getdtablesize_works" in
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| 54 | *yes | "no (limitation)") ;;
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| 55 | *) REPLACE_GETDTABLESIZE=1 ;;
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| 56 | esac
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| 57 | else
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| 58 | HAVE_GETDTABLESIZE=0
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| 59 | fi
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| 60 | ])
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| 61 |
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| 62 | # Prerequisites of lib/getdtablesize.c.
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| 63 | AC_DEFUN([gl_PREREQ_GETDTABLESIZE], [:])
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