Adapt vote reset code into fast campaign resetting

This is kind of a breaking change but the other code was obviously never
released or relied on by anyone - it will be pushed at the same time as
this in fact. It still seems worth having the original committed
separately to show the progression of development of the feature,
however. Technically the standalone vote cooldown resetting could also
be added back if ever desired however there doesn't seem to be that much
of a use case for that at the moment.

This feature ought to be a lot more convenient now as it allows for
resetting back to a set starting point no matter where the player is in
a run. It isn't universally useful as All Campaigns Legacy solo runs
require switching to a different type of server and Main Campaigns co-op
runs require restarting the game after Swamp Fever to work around the
god mode bug, however it is still useful in a good few situations.

Unfortunately this turned out to be pretty complex to implement, first
requiring a bunch of interop with valve's rather wacky KeyValues stuff,
and then requiring a bunch of especially difficult reverse engineering
of L4D1 v1.0.0.5 because it doesn't use said KeyValues stuff and does
something else completely different instead.

A side effect of all this work is that the nag removal hack is now part
of the KeyValues stuff in kvsys.c, which is kind of a comfier place for
it than just kind of dumped in the middle of sst.c.

1 files changed, 98 insertions, 0 deletions

diff --git a/src/kvsys.c b/src/kvsys.c
new file mode 100644
index 0000000..8bb140e
--- /dev/null
+++ b/src/kvsys.c
@@ -0,0 +1,98 @@
+/*
+ * 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 "engineapi.h"
+#include "extmalloc.h"
+#include "errmsg.h"
+#include "feature.h"
+#include "gametype.h"
+#include "hook.h"
+#include "kvsys.h"
+#include "mem.h"
+#include "os.h"
+#include "vcall.h"
+
+FEATURE()
+
+IMPORT void *KeyValuesSystem(void); // vstlib symbol
+static void *kvs;
+DECL_VFUNC(int, GetSymbolForString, 3, const char *, bool)
+DECL_VFUNC(const char *, GetStringForSymbol, 4, int)
+
+const char *kvsys_symtostr(int sym) { return GetStringForSymbol(kvs, sym); }
+int kvsys_strtosym(const char *s) { return GetSymbolForString(kvs, s, true); }
+
+struct KeyValues *kvsys_getsubkey(struct KeyValues *kv, int sym) {
+	for (kv = kv->child; kv; kv = kv->next) if (kv->keyname == sym) return kv;
+	return 0;
+}
+
+// this is trivial for now, but may need expansion later; see header comment
+const char *kvsys_getstrval(struct KeyValues *kv) { return kv->strval; }
+
+void kvsys_free(struct KeyValues *kv) {
+	while (kv) {
+		kvsys_free(kv->child);
+		struct KeyValues *next = kv->next;
+		// NOTE! could (should?) call the free function in IKeyValuesSystem but
+		// we instead assume pooling is compiled out in favour of the IMemAlloc
+		// stuff, and thus call the latter directly for less overhead
+		extfree(kv->strval); extfree(kv->wstrval);
+		extfree(kv);
+		kv = next;
+	}
+}
+
+// HACK: later versions of L4D2 show an annoying dialog on every plugin_load.
+// We can suppress this by catching the message string that's passed from
+// engine.dll to gameui.dll through KeyValuesSystem in vstdlib.dll and just
+// replacing it with some other arbitrary garbage string. This makes gameui fail
+// to match the message and thus do nothing. :)
+static GetStringForSymbol_func orig_GetStringForSymbol = 0;
+static const char *VCALLCONV hook_GetStringForSymbol(void *this, int s) {
+	const char *ret = orig_GetStringForSymbol(this, s);
+	if (!strcmp(ret, "OnClientPluginWarning")) ret = "sstBlockedThisEvent";
+	return ret;
+}
+
+INIT {
+	kvs = KeyValuesSystem();
+	// NOTE: this is technically redundant for early versions but I CBA writing
+	// a version check; it's easier to just do this unilaterally.
+	if (GAMETYPE_MATCHES(L4D2x)) {
+		void **kvsvt = mem_loadptr(kvs);
+		if (!os_mprot(kvsvt + vtidx_GetStringForSymbol, sizeof(void *),
+				PAGE_READWRITE)) {
+			errmsg_warnx("couldn't make KeyValuesSystem vtable writable");
+			errmsg_note("won't be able to prevent any nag messages");
+		}
+		else {
+			orig_GetStringForSymbol = (GetStringForSymbol_func)hook_vtable(
+					kvsvt, vtidx_GetStringForSymbol,
+					(void *)hook_GetStringForSymbol);
+		}
+	}
+	return true;
+}
+
+END {
+	if (orig_GetStringForSymbol) {
+		unhook_vtable(*(void ***)kvs, 4, (void *)orig_GetStringForSymbol);
+	}
+}
+
+// vi: sw=4 ts=4 noet tw=80 cc=80