Added warnings for ultrasafe and safe security modes (#30515)

code/__DEFINES/misc.dm

@@ -458,3 +458,8 @@ GLOBAL_LIST_INIT(ghost_others_options, list(GHOST_OTHERS_SIMPLE, GHOST_OTHERS_DE
 #define SHELLEO_ERRORLEVEL 1
 #define SHELLEO_STDOUT 2
 #define SHELLEO_STDERR 3
+
+//server security mode
+#define SECURITY_SAFE 1
+#define SECURITY_ULTRASAFE 2
+#define SECURITY_TRUSTED 3

code/game/world.dm

@@ -1,3 +1,6 @@
+GLOBAL_VAR(security_mode)
+GLOBAL_PROTECT(security_mode)
+
 /world/New()
 	log_world("World loaded at [time_stamp()]")
 
@@ -5,6 +8,8 @@
 
 	GLOB.config_error_log = GLOB.sql_error_log = GLOB.world_href_log = GLOB.world_runtime_log = GLOB.world_attack_log = GLOB.world_game_log = file("data/logs/config_error.log") //temporary file used to record errors with loading config, moved to log directory once logging is set bl
 
+	CheckSecurityMode()
+
 	make_datum_references_lists()	//initialises global lists for referencing frequently used datums (so that we only ever do it once)
 
 	config = new
@@ -94,6 +99,20 @@
 	if(GLOB.round_id)
 		log_game("Round ID: [GLOB.round_id]")
 
+/world/proc/CheckSecurityMode()
+	//try to write to data
+	if(!text2file("The world is running at least safe mode", "data/server_security_check.lock"))
+		GLOB.security_mode = SECURITY_ULTRASAFE
+		warning("/tg/station 13 is not supported in ultrasafe security mode. Everything will break!")
+		return
+	
+	//try to shell
+	if(shell("echo \"The world is running in trusted mode\"") != null)
+		GLOB.security_mode = SECURITY_TRUSTED
+	else
+		GLOB.security_mode = SECURITY_SAFE
+		warning("/tg/station 13 uses many file operations, a few shell()s, and some external call()s. Trusted mode is recommended. You can download our source code for your own browsing and compilation at https://github.com/tgstation/tgstation")
+
 /world/Topic(T, addr, master, key)
 	var/list/input = params2list(T)