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# select.m4 serial 14 |
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dnl Copyright (C) 2009-2023 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_SELECT], |
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[ |
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AC_REQUIRE([gl_SYS_SELECT_H]) |
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AC_REQUIRE([AC_C_RESTRICT]) |
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AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles |
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AC_REQUIRE([gl_SOCKETS]) |
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if test "$ac_cv_header_winsock2_h" = yes; then |
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REPLACE_SELECT=1 |
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else |
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dnl On Interix 3.5, select(0, NULL, NULL, NULL, timeout) fails with error |
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dnl EFAULT. |
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AC_CHECK_HEADERS_ONCE([sys/select.h]) |
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AC_CACHE_CHECK([whether select supports a 0 argument], |
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[gl_cv_func_select_supports0], |
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[ |
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AC_RUN_IFELSE([AC_LANG_SOURCE([[ |
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#include <sys/types.h> |
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#include <sys/time.h> |
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#if HAVE_SYS_SELECT_H |
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#include <sys/select.h> |
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#endif |
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int main () |
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{ |
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struct timeval timeout; |
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timeout.tv_sec = 0; |
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timeout.tv_usec = 5; |
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return select (0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &timeout) < 0; |
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}]])], [gl_cv_func_select_supports0=yes], [gl_cv_func_select_supports0=no], |
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[ |
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changequote(,)dnl |
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case "$host_os" in |
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# Guess no on Interix. |
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interix*) gl_cv_func_select_supports0="guessing no";; |
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# Guess yes otherwise. |
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*) gl_cv_func_select_supports0="guessing yes";; |
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esac |
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changequote([,])dnl |
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]) |
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]) |
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case "$gl_cv_func_select_supports0" in |
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*yes) ;; |
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*) REPLACE_SELECT=1 ;; |
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esac |
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dnl On FreeBSD 8.2, select() doesn't always reject bad fds. |
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AC_CACHE_CHECK([whether select detects invalid fds], |
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[gl_cv_func_select_detects_ebadf], |
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[ |
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AC_RUN_IFELSE([AC_LANG_PROGRAM([[ |
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#include <sys/types.h> |
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#include <sys/time.h> |
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#if HAVE_SYS_SELECT_H |
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# include <sys/select.h> |
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#endif |
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#include <unistd.h> |
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#include <errno.h> |
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]GL_MDA_DEFINES], |
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[[ |
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fd_set set; |
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dup2(0, 16); |
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FD_ZERO(&set); |
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FD_SET(16, &set); |
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close(16); |
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struct timeval timeout; |
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timeout.tv_sec = 0; |
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timeout.tv_usec = 5; |
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return select (17, &set, NULL, NULL, &timeout) != -1 || errno != EBADF; |
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]])], [gl_cv_func_select_detects_ebadf=yes], |
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[gl_cv_func_select_detects_ebadf=no], |
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[ |
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case "$host_os" in |
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# Guess yes on Linux systems. |
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linux-* | linux) gl_cv_func_select_detects_ebadf="guessing yes" ;; |
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# Guess yes on glibc systems. |
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*-gnu* | gnu*) gl_cv_func_select_detects_ebadf="guessing yes" ;; |
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# If we don't know, obey |
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*) gl_cv_func_select_detects_ebadf="$gl_cross_guess_normal" ;; |
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esac |
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]) |
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]) |
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case $gl_cv_func_select_detects_ebadf in |
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*yes) ;; |
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*) REPLACE_SELECT=1 ;; |
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esac |
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fi |
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dnl Determine the needed libraries. |
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SELECT_LIB="$LIBSOCKET" |
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if test $REPLACE_SELECT = 1; then |
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case "$host_os" in |
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mingw*) |
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dnl On the MSVC platform, the function MsgWaitForMultipleObjects |
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dnl (used in lib/select.c) requires linking with -luser32. On mingw, |
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dnl it is implicit. |
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AC_LINK_IFELSE( |
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[AC_LANG_SOURCE([[ |
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#define WIN32_LEAN_AND_MEAN |
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#include <windows.h> |
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int |
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main () |
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{ |
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MsgWaitForMultipleObjects (0, NULL, 0, 0, 0); |
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return 0; |
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}]])], |
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[], |
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[SELECT_LIB="$SELECT_LIB -luser32"]) |
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;; |
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esac |
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fi |
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AC_SUBST([SELECT_LIB]) |
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dnl For backward compatibility. |
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LIB_SELECT="$LIB_SELECT" |
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AC_SUBST([LIB_SELECT]) |
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]) |
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