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-rw-r--r--m4/select.m4117
1 files changed, 117 insertions, 0 deletions
diff --git a/m4/select.m4 b/m4/select.m4
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+++ b/m4/select.m4
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+# select.m4 serial 12
+dnl Copyright (C) 2009-2020 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_SELECT],
+[
+ AC_REQUIRE([gl_HEADER_SYS_SELECT])
+ AC_REQUIRE([AC_C_RESTRICT])
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+ AC_REQUIRE([gl_SOCKETS])
+ if test "$ac_cv_header_winsock2_h" = yes; then
+ REPLACE_SELECT=1
+ else
+ dnl On Interix 3.5, select(0, NULL, NULL, NULL, timeout) fails with error
+ dnl EFAULT.
+ AC_CHECK_HEADERS_ONCE([sys/select.h])
+ AC_CACHE_CHECK([whether select supports a 0 argument],
+ [gl_cv_func_select_supports0],
+ [
+ AC_RUN_IFELSE([AC_LANG_SOURCE([[
+#include <sys/types.h>
+#include <sys/time.h>
+#if HAVE_SYS_SELECT_H
+#include <sys/select.h>
+#endif
+int main ()
+{
+ struct timeval timeout;
+ timeout.tv_sec = 0;
+ timeout.tv_usec = 5;
+ return select (0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &timeout) < 0;
+}]])], [gl_cv_func_select_supports0=yes], [gl_cv_func_select_supports0=no],
+ [
+changequote(,)dnl
+ case "$host_os" in
+ # Guess no on Interix.
+ interix*) gl_cv_func_select_supports0="guessing no";;
+ # Guess yes otherwise.
+ *) gl_cv_func_select_supports0="guessing yes";;
+ esac
+changequote([,])dnl
+ ])
+ ])
+ case "$gl_cv_func_select_supports0" in
+ *yes) ;;
+ *) REPLACE_SELECT=1 ;;
+ esac
+
+ dnl On FreeBSD 8.2, select() doesn't always reject bad fds.
+ AC_CACHE_CHECK([whether select detects invalid fds],
+ [gl_cv_func_select_detects_ebadf],
+ [
+ AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <sys/types.h>
+#include <sys/time.h>
+#if HAVE_SYS_SELECT_H
+# include <sys/select.h>
+#endif
+#include <unistd.h>
+#include <errno.h>
+]GL_MDA_DEFINES],
+[[
+ fd_set set;
+ dup2(0, 16);
+ FD_ZERO(&set);
+ FD_SET(16, &set);
+ close(16);
+ struct timeval timeout;
+ timeout.tv_sec = 0;
+ timeout.tv_usec = 5;
+ return select (17, &set, NULL, NULL, &timeout) != -1 || errno != EBADF;
+]])], [gl_cv_func_select_detects_ebadf=yes],
+ [gl_cv_func_select_detects_ebadf=no],
+ [
+ case "$host_os" in
+ # Guess yes on Linux systems.
+ linux-* | linux) gl_cv_func_select_detects_ebadf="guessing yes" ;;
+ # Guess yes on glibc systems.
+ *-gnu* | gnu*) gl_cv_func_select_detects_ebadf="guessing yes" ;;
+ # If we don't know, obey --enable-cross-guesses.
+ *) gl_cv_func_select_detects_ebadf="$gl_cross_guess_normal" ;;
+ esac
+ ])
+ ])
+ case $gl_cv_func_select_detects_ebadf in
+ *yes) ;;
+ *) REPLACE_SELECT=1 ;;
+ esac
+ fi
+
+ dnl Determine the needed libraries.
+ LIB_SELECT="$LIBSOCKET"
+ if test $REPLACE_SELECT = 1; then
+ case "$host_os" in
+ mingw*)
+ dnl On the MSVC platform, the function MsgWaitForMultipleObjects
+ dnl (used in lib/select.c) requires linking with -luser32. On mingw,
+ dnl it is implicit.
+ AC_LINK_IFELSE(
+ [AC_LANG_SOURCE([[
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+int
+main ()
+{
+ MsgWaitForMultipleObjects (0, NULL, 0, 0, 0);
+ return 0;
+}]])],
+ [],
+ [LIB_SELECT="$LIB_SELECT -luser32"])
+ ;;
+ esac
+ fi
+ AC_SUBST([LIB_SELECT])
+])