| # getdtablesize.m4 serial 8 |
| dnl Copyright (C) 2008-2021 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], [:]) |
