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