gnulib: import select

A few sims use this to emulate the syscall & provide network
functionality.

gnulib/import/m4/socketlib.m4

@@ -0,0 +1,96 @@
+# socketlib.m4 serial 3
+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.
+
+dnl gl_SOCKETLIB
+dnl Determines the library to use for socket functions.
+dnl Sets and AC_SUBSTs LIBSOCKET.
+
+AC_DEFUN([gl_SOCKETLIB],
+[
+  gl_PREREQ_SYS_H_WINSOCK2 dnl for HAVE_WINSOCK2_H
+  LIBSOCKET=
+  if test $HAVE_WINSOCK2_H = 1; then
+    dnl Native Windows API (not Cygwin).
+    dnl If the function WSAStartup exists (declared in <winsock2.h> and
+    dnl defined through -lws2_32), we need to call it.
+    AC_CACHE_CHECK([for WSAStartup],
+      [gl_cv_func_wsastartup], [
+       gl_save_LIBS="$LIBS"
+       LIBS="$LIBS -lws2_32"
+       AC_LINK_IFELSE(
+         [AC_LANG_PROGRAM([[
+#ifdef HAVE_WINSOCK2_H
+# include <winsock2.h>
+#endif]], [[
+            WORD wVersionRequested = MAKEWORD(1, 1);
+            WSADATA wsaData;
+            int err = WSAStartup(wVersionRequested, &wsaData);
+            WSACleanup ();
+            ]])
+         ],
+         [gl_cv_func_wsastartup=yes],
+         [gl_cv_func_wsastartup=no])
+       LIBS="$gl_save_LIBS"
+      ])
+    if test "$gl_cv_func_wsastartup" = "yes"; then
+      AC_DEFINE([WINDOWS_SOCKETS], [1], [Define if WSAStartup is needed.])
+      LIBSOCKET='-lws2_32'
+    fi
+  else
+    dnl Unix API.
+    dnl Solaris has most socket functions in libsocket.
+    dnl Haiku has most socket functions in libnetwork.
+    dnl BeOS has most socket functions in libnet.
+    dnl On HP-UX, do NOT link with libxnet, because in 64-bit mode this would
+    dnl break code (e.g. in libraries) that invokes accept(), getpeername(),
+    dnl getsockname(), getsockopt(), or recvfrom() with a 32-bit addrlen. See
+    dnl "man xopen_networking" for details.
+    AC_CACHE_CHECK([for library containing setsockopt], [gl_cv_lib_socket], [
+      gl_cv_lib_socket=
+      AC_LINK_IFELSE([AC_LANG_PROGRAM([[extern
+#ifdef __cplusplus
+"C"
+#endif
+char setsockopt();]], [[setsockopt();]])],
+        [],
+        [gl_save_LIBS="$LIBS"
+         LIBS="$gl_save_LIBS -lsocket"
+         AC_LINK_IFELSE([AC_LANG_PROGRAM([[extern
+#ifdef __cplusplus
+"C"
+#endif
+char setsockopt();]], [[setsockopt();]])],
+           [gl_cv_lib_socket="-lsocket"])
+         if test -z "$gl_cv_lib_socket"; then
+           LIBS="$gl_save_LIBS -lnetwork"
+           AC_LINK_IFELSE([AC_LANG_PROGRAM([[extern
+#ifdef __cplusplus
+"C"
+#endif
+char setsockopt();]], [[setsockopt();]])],
+             [gl_cv_lib_socket="-lnetwork"])
+           if test -z "$gl_cv_lib_socket"; then
+             LIBS="$gl_save_LIBS -lnet"
+             AC_LINK_IFELSE([AC_LANG_PROGRAM([[extern
+#ifdef __cplusplus
+"C"
+#endif
+char setsockopt();]], [[setsockopt();]])],
+               [gl_cv_lib_socket="-lnet"])
+           fi
+         fi
+         LIBS="$gl_save_LIBS"
+        ])
+      if test -z "$gl_cv_lib_socket"; then
+        gl_cv_lib_socket="none needed"
+      fi
+    ])
+    if test "$gl_cv_lib_socket" != "none needed"; then
+      LIBSOCKET="$gl_cv_lib_socket"
+    fi
+  fi
+  AC_SUBST([LIBSOCKET])
+])