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/).

1 files changed, 76 insertions, 0 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