Cancel fast-forward after the player disconnects

Avoids spurious and confusing fast-forward behaviour in the event of
resetting a run, then disconnecting early and deciding to load some
other map.

Also fixes a stupid typo (s/propand/propane/).

3 files changed, 125 insertions, 10 deletions

diff --git a/src/gameserver.c b/src/gameserver.c
new file mode 100644
index 0000000..5a76027
--- /dev/null
+++ b/src/gameserver.c
@@ -0,0 +1,76 @@
+/*
+ * Copyright © 2023 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "con_.h"
+#include "errmsg.h"
+#include "feature.h"
+#include "gamedata.h"
+#include "intdefs.h"
+#include "mem.h"
+#include "x86.h"
+#include "vcall.h"
+#include "x86util.h"
+
+FEATURE()
+REQUIRE_GAMEDATA(vtidx_GetSpawnCount)
+
+DECL_VFUNC_DYN(int, GetSpawnCount)
+
+static void *sv;
+
+int gameserver_spawncount(void) { return GetSpawnCount(sv); }
+
+static bool find_sv(con_cmdcb pause_cb) {
+#ifdef _WIN32
+	// The last thing pause does is call BroadcastPrintf with 4 args including
+	// `this`, all on the stack since it's varargs. 2 of the args are pushed
+	// immediately before `this`, so we can just look for 3 back-to-back pushes
+	// and a call.
+	const uchar *insns = (const uchar *)pause_cb;
+	int pushes = 0;
+	for (const uchar *p = insns; p - insns < 256;) {
+		if (*p == X86_PUSHIW || *p >= X86_PUSHEAX && *p <= X86_PUSHEDI) {
+			if (++pushes == 3) {
+				if (*p != X86_PUSHIW || p[5] != X86_CALL) {
+					// it'd be super weird to have this many pushes anywhere
+					// else in the function, so give up here
+					return false;
+				}
+				sv = mem_loadptr(p + 1);
+				return true;
+			}
+		}
+		else {
+			pushes = 0;
+		}
+		NEXT_INSN(p, "load of sv pointer");
+	}
+#else
+#warning TODO(linux): the usual x86 stuff
+#endif
+	return false;
+}
+
+INIT {
+	struct con_cmd *pause = con_findcmd("pause");
+	if (!find_sv(pause->cb)) {
+		errmsg_errorx("couldn't find game server object\n");
+		return false;
+	}
+	return true;
+}
+
+// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/gameserver.h b/src/gameserver.h
new file mode 100644
index 0000000..f27ad5c
--- /dev/null
+++ b/src/gameserver.h
@@ -0,0 +1,28 @@
+/*
+ * Copyright © 2023 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef INC_GAMESERVER_H
+#define INC_GAMESERVER_H
+
+/*
+ * Returns the spawn count / server number which the engine increments every new
+ * map. Can be used to help keep track of map changes, disconnects and such.
+ */
+int gameserver_spawncount(void);
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/l4dreset.c b/src/l4dreset.c
index c228665..479a1c8 100644
--- a/src/l4dreset.c
+++ b/src/l4dreset.c
@@ -26,6 +26,7 @@
 #include "feature.h"
 #include "gamedata.h"
 #include "gametype.h"
+#include "gameserver.h"
 #include "hook.h"
 #include "intdefs.h"
 #include "l4dmm.h"
@@ -42,6 +43,7 @@
 FEATURE("Left 4 Dead quick resetting")
 REQUIRE(ent)
 REQUIRE(fastfwd)
+REQUIRE(gameserver)
 REQUIRE(l4dmm)
 REQUIRE_GLOBAL(srvdll)
 REQUIRE_GAMEDATA(vtidx_GameFrame) // note: for L4D1 only, always defined anyway
@@ -119,7 +121,7 @@ static const schar ffsegs[] = {
 	- 9, // No Mercy
 	  4, // Swamp Fever
 	  3, // - seen first propane
-	-12, // - second propand. Also: Death Toll; Dead Air (L4D1); Dark Carnival
+	-12, // - second propane. Also: Death Toll; Dead Air (L4D1); Dark Carnival
 	-15, // Blood Harvest (L4D1); The Sacrifice (L4D1)
 	- 8, // Crash Course; Hard Rain
 	-13, // Dead Center; The Parish; Dead Air (L4D2)
@@ -148,9 +150,9 @@ static const schar ffsegs[] = {
 #define FFIDX_STREAM 11
 
 static schar ffidx;
-static short ffdelay;
+static short ffdelay = 0;
 static float ffadj = 0;
-static bool mapchanging = false;
+static int nextmapnum = 0;
 
 DEF_CVAR_MINMAX_UNREG(sst_l4d_quickreset_peektime,
 		"Number of seconds to show each relevant item spot during fast-forward",
@@ -170,7 +172,7 @@ DEF_CCMD_HERE_UNREG(sst_l4d_quickreset_continue,
 }
 
 HANDLE_EVENT(Tick, bool simulating) {
-	if (!mapchanging && simulating && ffdelay && !--ffdelay) {
+	if (!nextmapnum && simulating && ffdelay && !--ffdelay) {
 		schar seg = ffsegs[ffidx];
 		float halfwin = con_getvarf(sst_l4d_quickreset_peektime) / 2.0f;
 		float t;
@@ -193,8 +195,13 @@ typedef void (*VCALLCONV OnGameplayStart_func)(void *this);
 static OnGameplayStart_func orig_OnGameplayStart;
 static void VCALLCONV hook_OnGameplayStart(void *this) {
 	orig_OnGameplayStart(this);
-	if (mapchanging) reset(); // prevent bots walking around. note ffdelay is 45
-	mapchanging = false; // resume countdown!
+	if (nextmapnum) {
+		// if we changed map more than 1 time, cancel the reset. this'll happen
+		// if someone prematurely disconnects and then starts a new session.
+		if (nextmapnum != gameserver_spawncount()) ffdelay = 0;
+		else reset(); // prevent bots walking around. note ffdelay is stil 45
+	}
+	nextmapnum = 0; // resume countdown if there is one! otherwise do nothing.
 }
 // Simply reuse the above for L4D1, since the calling ABI is the exact same!
 #define UnfreezeTeam_func OnGameplayStart_func
@@ -262,13 +269,17 @@ DEF_CCMD_HERE_UNREG(sst_l4d_quickreset,
 	if (cmd->argc == 2 && (!campaign || strcasecmp(campaign, cmd->argv[1]))) {
 		change(cmd->argv[1]);
 		campaign = cmd->argv[1];
-		mapchanging = true;
+		nextmapnum = gameserver_spawncount() + 1; // immediate next changelevel
 	}
 	else {
 		reset();
-		// same-map reset is delayed by about a second - save that time here
-		// also, set mapchanging back to false in case it got stuck somehow
-		if (!(mapchanging = !l4dmm_firstmap())) fastfwd(0.8, 10);
+		if (l4dmm_firstmap()) {
+			fastfwd(0.8, 10); // same-map reset is delayed by about a second
+			nextmapnum = 0; // reset this just in case it got stuck... somehow?
+		}
+		else {
+			nextmapnum = gameserver_spawncount() + 1; // same as above
+		}
 	}
 	if (campaign && con_getvari(sst_l4d_quickreset_fastfwd) &&
 			(ffidx = getffidx(campaign)) != -1) {