From f6fd9144f16af8c07eab26e1ee4347b173626907 Mon Sep 17 00:00:00 2001
From: Des <xon@damianv.com.ar>
Date: Thu, 15 Aug 2024 13:42:51 -0300
Subject: [PATCH] Remove support for \ as escape character for everything but
 "\\", "\n" and "\%". Keep a warning for previously valid escape characters
 (except mutator ones, if they exists).

---
 qcsrc/server/chat.qc | 54 ++++++++++++++++++++++++++++----------------
 1 file changed, 35 insertions(+), 19 deletions(-)

diff --git a/qcsrc/server/chat.qc b/qcsrc/server/chat.qc
index f3870e618..54756f69d 100644
--- a/qcsrc/server/chat.qc
+++ b/qcsrc/server/chat.qc
@@ -499,7 +499,8 @@ string formatmessage(entity this, string msg)
 	float escapesize, msglen;
 	vector cursor = '0 0 0';
 	entity cursor_ent = NULL;
-	string escape;
+	string escape,escape_token;
+	bool warn_slash = false;
 	string replacement;
 	p = 0;
 	n = 7;
@@ -538,29 +539,38 @@ string formatmessage(entity this, string msg)
 
 		msglen = strlen(msg);
 		replacement = substring(msg, p, escapesize);
+		escape_token = substring(msg, p, 1);
 		escape = substring(msg, p + 1, 1);
 
 		.entity weaponentity = weaponentities[0]; // TODO: unhardcode
 
+#define ON_SLASH() MACRO_BEGIN warn_slash = false; if(escape_token != "\\") break; MACRO_END
+#define NO_SLASH() MACRO_BEGIN if(escape_token == "\\") break; MACRO_END
+// TODO: remove warn_slash before next release (xonotic-v0.9.0)
+// this is only to warn users of backslash expansions for anything other than '\%', '\\' and '\n'
+		if(escape_token == "\\")
+			warn_slash = true;
+		else
+			warn_slash = false;
 		switch(escape)
 		{
-			case "%": replacement = "%"; break;
-			case "\\":replacement = "\\"; break;
-			case "n": replacement = "\n"; break;
-			case "a": replacement = ftos(floor(GetResource(this, RES_ARMOR))); break;
-			case "h": replacement = PlayerHealth(this); break;
-			case "l": replacement = NearestLocation(this.origin); break;
-			case "y": replacement = NearestLocation(cursor); break;
-			case "d": replacement = NearestLocation(this.death_origin); break;
-			case "o": replacement = vtos(this.origin); break;
-			case "O": replacement = sprintf("'%f %f %f'", this.origin.x, this.origin.y, this.origin.z); break;
-			case "w": replacement = WeaponNameFromWeaponentity(this, weaponentity); break;
-			case "W": replacement = GetAmmoName(this.(weaponentity).m_weapon.ammo_type); break;
-			case "x": replacement = ((cursor_ent.netname == "" || !cursor_ent) ? "nothing" : cursor_ent.netname); break;
-			case "s": replacement = ftos(vlen(this.velocity - this.velocity_z * '0 0 1')); break;
-			case "S": replacement = ftos(vlen(this.velocity)); break;
-			case "t": replacement = seconds_tostring(ceil(max(0, autocvar_timelimit * 60 + game_starttime - time))); break;
-			case "T": replacement = seconds_tostring(floor(time - game_starttime)); break;
+			case "%":             replacement = "%"; warn_slash = false; break;
+			case "\\":ON_SLASH(); replacement = "\\"; break;
+			case "n": ON_SLASH(); replacement = "\n"; break;
+			case "a": NO_SLASH(); replacement = ftos(floor(GetResource(this, RES_ARMOR))); break;
+			case "h": NO_SLASH(); replacement = PlayerHealth(this); break;
+			case "l": NO_SLASH(); replacement = NearestLocation(this.origin); break;
+			case "y": NO_SLASH(); replacement = NearestLocation(cursor); break;
+			case "d": NO_SLASH(); replacement = NearestLocation(this.death_origin); break;
+			case "o": NO_SLASH(); replacement = vtos(this.origin); break;
+			case "O": NO_SLASH(); replacement = sprintf("'%f %f %f'", this.origin.x, this.origin.y, this.origin.z); break;
+			case "w": NO_SLASH(); replacement = WeaponNameFromWeaponentity(this, weaponentity); break;
+			case "W": NO_SLASH(); replacement = GetAmmoName(this.(weaponentity).m_weapon.ammo_type); break;
+			case "x": NO_SLASH(); replacement = ((cursor_ent.netname == "" || !cursor_ent) ? "nothing" : cursor_ent.netname); break;
+			case "s": NO_SLASH(); replacement = ftos(vlen(this.velocity - this.velocity_z * '0 0 1')); break;
+			case "S": NO_SLASH(); replacement = ftos(vlen(this.velocity)); break;
+			case "t": NO_SLASH(); replacement = seconds_tostring(ceil(max(0, autocvar_timelimit * 60 + game_starttime - time))); break;
+			case "T": NO_SLASH(); replacement = seconds_tostring(floor(time - game_starttime)); break;
 			case "1":
 			case "2":
 			case "3":
@@ -571,18 +581,24 @@ string formatmessage(entity this, string msg)
 			case "8":
 			case "9":
 			{
+				NO_SLASH();
 				while (msglen > p+escapesize  && IS_DIGIT(substring(msg,p+escapesize,1))) escapesize = escapesize + 1;
 				replacement = GetFilteredEntity(substring(msg, p + 1, escapesize)).netname;
 				break;
 			}
 			default:
 			{
+				warn_slash = false; // too noisy
+				NO_SLASH();
 				MUTATOR_CALLHOOK(FormatMessage, this, escape, replacement, msg);
 				replacement = M_ARGV(2, string);
 				break;
 			}
 		}
-
+#undef ON_SLASH
+#undef NO_SLASH
+		if(warn_slash)
+			PrintToChat(this, sprintf("^3WARNING: unsupported \"\\%s\" expansion, use \"%%%s\"", escape, escape));
 		msg = strcat(substring(msg, 0, p), replacement, substring(msg, p+escapesize, strlen(msg) - (p+escapesize)));
 		p = p + strlen(replacement);
 	}
-- 
2.39.2