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61 lines
2.5 KiB
Plaintext
61 lines
2.5 KiB
Plaintext
# getdtablesize.m4 serial 7
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dnl Copyright (C) 2008-2020 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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AC_DEFUN([gl_FUNC_GETDTABLESIZE],
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[
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AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
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AC_REQUIRE([AC_CANONICAL_HOST])
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AC_CHECK_FUNCS_ONCE([getdtablesize])
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AC_CHECK_DECLS_ONCE([getdtablesize])
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if test $ac_cv_func_getdtablesize = yes &&
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test $ac_cv_have_decl_getdtablesize = yes; then
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AC_CACHE_CHECK([whether getdtablesize works],
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[gl_cv_func_getdtablesize_works],
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[dnl There are two concepts: the "maximum possible file descriptor value + 1"
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dnl and the "maximum number of open file descriptors in a process".
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dnl Per SUSv2 and POSIX, getdtablesize() should return the first one.
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dnl On most platforms, the first and the second concept are the same.
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dnl On OpenVMS, however, they are different and getdtablesize() returns
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dnl the second one; thus the test below fails. But we don't care
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dnl because there's no good way to write a replacement getdtablesize().
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case "$host_os" in
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vms*) gl_cv_func_getdtablesize_works="no (limitation)" ;;
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*)
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dnl Cygwin 1.7.25 automatically increases the RLIMIT_NOFILE soft
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dnl limit up to an unchangeable hard limit; all other platforms
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dnl correctly require setrlimit before getdtablesize() can report
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dnl a larger value.
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AC_RUN_IFELSE([
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AC_LANG_PROGRAM([[#include <unistd.h>]],
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[int size = getdtablesize();
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if (dup2 (0, getdtablesize()) != -1)
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return 1;
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if (size != getdtablesize())
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return 2;
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])],
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[gl_cv_func_getdtablesize_works=yes],
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[gl_cv_func_getdtablesize_works=no],
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[case "$host_os" in
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cygwin*) # on cygwin 1.5.25, getdtablesize() automatically grows
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gl_cv_func_getdtablesize_works="guessing no" ;;
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*) gl_cv_func_getdtablesize_works="guessing yes" ;;
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esac
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])
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;;
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esac
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])
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case "$gl_cv_func_getdtablesize_works" in
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*yes | "no (limitation)") ;;
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*) REPLACE_GETDTABLESIZE=1 ;;
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esac
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else
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HAVE_GETDTABLESIZE=0
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fi
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])
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# Prerequisites of lib/getdtablesize.c.
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AC_DEFUN([gl_PREREQ_GETDTABLESIZE], [:])
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