Main: move WinSock initialization to class ScopeNetInit

Makefile.am

@@ -497,6 +497,7 @@ libthread_a_SOURCES = \
 
 libnet_a_SOURCES = \
 	src/net/Features.hxx \
+	src/net/Init.hxx \
 	src/net/ToString.cxx src/net/ToString.hxx \
 	src/net/Resolver.cxx src/net/Resolver.hxx \
 	src/net/StaticSocketAddress.cxx src/net/StaticSocketAddress.hxx \

src/Main.cxx

@@ -50,6 +50,7 @@
 #include "unix/SignalHandlers.hxx"
 #include "system/FatalError.hxx"
 #include "thread/Slack.hxx"
+#include "net/Init.hxx"
 #include "lib/icu/Init.hxx"
 #include "config/ConfigGlobal.hxx"
 #include "config/Param.hxx"
@@ -106,11 +107,6 @@
 #include <locale.h>
 #endif
 
-#ifdef _WIN32
-#include <winsock2.h>
-#include <ws2tcpip.h>
-#endif
-
 #ifdef __BLOCKS__
 #include <dispatch/dispatch.h>
 #endif
@@ -284,25 +280,6 @@ glue_state_file_init()
 	instance->state_file->Read();
 }
 
-/**
- * Windows-only initialization of the Winsock2 library.
- */
-static void winsock_init(void)
-{
-#ifdef _WIN32
-	WSADATA sockinfo;
-
-	int retval = WSAStartup(MAKEWORD(2, 2), &sockinfo);
-	if(retval != 0)
-		FormatFatalError("Attempt to open Winsock2 failed; error code %d",
-				 retval);
-
-	if (LOBYTE(sockinfo.wVersion) != 2)
-		FatalError("We use Winsock2 but your version is either too new "
-			   "or old; please install Winsock 2.x");
-#endif
-}
-
 /**
  * Initialize the decoder and player core, including the music pipe.
  */
@@ -451,7 +428,8 @@ try {
 
 	IcuInit();
 
-	winsock_init();
+	const ScopeNetInit net_init;
+
 	io_thread_init();
 	config_global_init();
 
@@ -702,10 +680,6 @@ try {
 	daemonize_finish();
 #endif
 
-#ifdef _WIN32
-	WSACleanup();
-#endif
-
 	IcuFinish();
 
 	log_deinit();

src/net/Init.hxx

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2003-2017 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef NET_INIT_HXX
+#define NET_INIT_HXX
+
+#include "check.h"
+#include "SocketError.hxx"
+
+#ifdef _WIN32
+#include <winsock2.h>
+#endif
+
+class ScopeNetInit {
+#ifdef _WIN32
+public:
+	ScopeNetInit() {
+		WSADATA sockinfo;
+		int retval = WSAStartup(MAKEWORD(2, 2), &sockinfo);
+		if (retval != 0)
+			throw MakeSocketError(retval, "WSAStartup() failed");
+	}
+
+	~ScopeNetInit() noexcept {
+		WSACleanup();
+	}
+#endif
+};
+
+#endif