mirror of https://gitee.com/openkylin/wget.git
123 lines
3.7 KiB
Plaintext
123 lines
3.7 KiB
Plaintext
# select.m4 serial 15
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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 systems that emulate the Linux system calls.
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midipix*) 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 --enable-cross-guesses.
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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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