From 15da50c815aa74e6132a9aa3df59c9f17bd6b4c3 Mon Sep 17 00:00:00 2001
From: rubenwardy <rw@rubenwardy.com>
Date: Mon, 12 Nov 2018 14:34:01 +0000
Subject: [PATCH] Fix get_server_status() segfault due to uninitialized m_env

Fixes #7857
---
 src/server.cpp | 58 ++++++++++++++++++++++++++++----------------------
 1 file changed, 33 insertions(+), 25 deletions(-)

diff --git a/src/server.cpp b/src/server.cpp
index 71a349b08..ef282ec51 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -334,7 +334,7 @@ Server::~Server()
 
 	{
 		MutexAutoLock envlock(m_env_mutex);
-		
+
 		infostream << "Server: Saving players" << std::endl;
 		m_env->saveLoadedPlayers();
 
@@ -3013,36 +3013,44 @@ PlayerSAO* Server::getPlayerSAO(u16 peer_id)
 std::wstring Server::getStatusString()
 {
 	std::wostringstream os(std::ios_base::binary);
-	os<<L"# Server: ";
+	os << L"# Server: ";
 	// Version
-	os<<L"version="<<narrow_to_wide(g_version_string);
+	os << L"version=" << narrow_to_wide(g_version_string);
 	// Uptime
-	os<<L", uptime="<<m_uptime.get();
+	os << L", uptime=" << m_uptime.get();
 	// Max lag estimate
-	os<<L", max_lag="<<m_env->getMaxLagEstimate();
+	os << L", max_lag=" << (m_env ? m_env->getMaxLagEstimate() : 0);
+
 	// Information about clients
 	bool first = true;
-	os<<L", clients={";
-	std::vector<u16> clients = m_clients.getClientIDs();
-	for (std::vector<u16>::iterator i = clients.begin(); i != clients.end(); ++i) {
-		// Get player
-		RemotePlayer *player = m_env->getPlayer(*i);
-		// Get name of player
-		std::wstring name = L"unknown";
-		if (player != NULL)
-			name = narrow_to_wide(player->getName());
-		// Add name to information string
-		if(!first)
-			os << L", ";
-		else
-			first = false;
-		os << name;
+	os << L", clients={";
+	if (m_env) {
+		std::vector<session_t> clients = m_clients.getClientIDs();
+		for (session_t client_id : clients) {
+			RemotePlayer *player = m_env->getPlayer(client_id);
+
+			// Get name of player
+			std::wstring name = L"unknown";
+			if (player)
+				name = narrow_to_wide(player->getName());
+
+			// Add name to information string
+			if (!first)
+				os << L", ";
+			else
+				first = false;
+
+			os << name;
+		}
 	}
 	os << L"}";
-	if(((ServerMap*)(&m_env->getMap()))->isSavingEnabled() == false)
-		os<<std::endl<<L"# Server: "<<" WARNING: Map saving is disabled.";
-	if(g_settings->get("motd") != "")
-		os<<std::endl<<L"# Server: "<<narrow_to_wide(g_settings->get("motd"));
+
+	if (m_env && !((ServerMap*)(&m_env->getMap()))->isSavingEnabled())
+		os << std::endl << L"# Server: " << " WARNING: Map saving is disabled.";
+
+	if (!g_settings->get("motd").empty())
+		os << std::endl << L"# Server: " << narrow_to_wide(g_settings->get("motd"));
+
 	return os.str();
 }
 
@@ -3577,7 +3585,7 @@ void Server::requestShutdown(const std::string &msg, bool reconnect, float delay
 	if (delay == 0.0f) {
 	// No delay, shutdown immediately
 		m_shutdown_requested = true;
-		// only print to the infostream, a chat message saying 
+		// only print to the infostream, a chat message saying
 		// "Server Shutting Down" is sent when the server destructs.
 		infostream << "*** Immediate Server shutdown requested." << std::endl;
 	} else if (delay < 0.0f && m_shutdown_timer > 0.0f) {