Get it sort-of-mostly working in "Old Engine" HL2HEADmaster

While we're at it, come up with a way for certain gamedata matches to be
Windows-only. Somewhat reduces ifdef usage, although does not entirely
remove it of course.

Tested in HL2 2707. Haven't tested other HL2 builds, or Episode 1.
Doesn't seem to work in DMoMM yet either; not sure why.

A big list of stuff still to fix follows.

Hidden cvars are currently an issue. We still need to figure out what to
do with the flag bits because FCVAR_HIDDEN just doesn't exist in OE and
there's some other flag with the same value instead.

We also need to do something about the flag setting in fixes.c since
HIDDEN is again not a thing, and also DEVONLY is not a thing either.

When the plugin is autoloaded, all the initial log text gets eaten,
because there's some stupid crap we have to do to trick the engine into
displaying coloured text otherwise it just won't. Not even stuff from
Warning(). Very stupid, but Hayden already figured out a solution, so
that'll be done in another upcoming commit.

Apparently raw mouse input breaks the menu. We might need to bump up the
priority on making that hook only be active when there's no UI open -
something I wanted to do anyway due to the demo drive issues.

Big thanks to Hayden for doing a lot of the initial groundwork on this,
particularly the cvar registration stuff. He gets a copyright notice in
con_.c even though I ended up doing a lot of stuff differently because
quite a bit of his work is still in there.

Don't blame him for the self-modifying code though, that was my crazy
idea. Sorry, but, in my defence... Well, it works.

1 files changed, 61 insertions, 32 deletions

diff --git a/src/sst.c b/src/sst.c
index 7fd0275..7e1960e 100644
--- a/src/sst.c
+++ b/src/sst.c
@@ -37,6 +37,7 @@
 #include "hook.h"
 #include "intdefs.h"
 #include "langext.h"
+#include "mem.h" // for shuntvars() in generated code
 #include "os.h"
 #include "sst.h"
 #include "vcall.h"
@@ -322,16 +323,15 @@ static void do_featureinit() {
 	}
 	void *inputsystemlib = os_dlhandle(OS_LIT("bin/") OS_LIT("inputsystem")
 			OS_LIT(OS_DLSUFFIX));
-	if_cold (!inputsystemlib) {
-		errmsg_warndl("couldn't get the input system library");
-	}
-	else if_cold (!(factory_inputsystem = (ifacefactory)os_dlsym(inputsystemlib,
-			"CreateInterface"))) {
-		errmsg_warndl("couldn't get input system's CreateInterface");
-	}
-	else if_cold (!(inputsystem = factory_inputsystem(
-			"InputSystemVersion001", 0))) {
-		errmsg_warnx("missing input system interface");
+	if (inputsystemlib) { // might not have this, e.g. in OE. no point warning
+		if_cold (!(factory_inputsystem = (ifacefactory)os_dlsym(inputsystemlib,
+				"CreateInterface"))) {
+			errmsg_warndl("couldn't get input system's CreateInterface");
+		}
+		else if_cold (!(inputsystem = factory_inputsystem(
+				"InputSystemVersion001", 0))) {
+			errmsg_warnx("missing input system interface");
+		}
 	}
 	// ... and now for the real magic! (n.b. this also registers feature cvars)
 	initfeatures();
@@ -344,7 +344,7 @@ if (GAMETYPE_MATCHES(x)) { \
 	con_colourmsg(&purple, "%s%s", first ? "" : ", ", #x); \
 	first = false; \
 }
-	GAMETYPE_BASETAGS(PRINTTAG)
+	GAMETYPE_BASETAGS(PRINTTAG, PRINTTAG)
 #undef PRINTTAG
 	con_colourmsg(&purple, "\n"); // xkcd 2109-compliant whitespace
 #endif
@@ -421,13 +421,17 @@ static struct con_cmd *cmd_plugin_load, *cmd_plugin_unload;
 
 static int ownidx; // XXX: super hacky way of getting this to do_unload()
 
-static bool ispluginv1(const struct CPlugin *plugin) {
-	// basename string is set with strncpy(), so if there's null bytes with more
-	// stuff after, we can't be looking at a v2 struct. and we expect null bytes
-	// in ifacever, since it's a small int value
-	return (plugin->basename[0] == 0 || plugin->basename[0] == 1) &&
-			plugin->v1.theplugin && plugin->v1.ifacever < 256 &&
-			plugin->v1.ifacever;
+static int detectpluginver(const struct CPlugin *plugin) {
+	// if the first byte of basename is not 0 or 1, it can't be a bool value for
+	// paused, so this must be v3. XXX: there's an edge case where a string
+	// that starts with a 1 byte could be miscategorised but that should never
+	// happen in practice. still if we can think of a cleverer way around that
+	// it might be nice for the sake of absolute robustness.
+	if ((uchar)plugin->basename[0] > 1) return 3;
+	// if ifacever is not a small nonzero integer, it's not a version. treat it
+	// as the (possibly null) plugin pointer - meaning this is v1.
+	if (!plugin->v2.ifacever || (uint)plugin->v2.ifacever > 255) return 1;
+	return 2; // otherwise we just assume it must be v2!
 }
 
 DEF_CCMD_COMPAT_HOOK(plugin_load) {
@@ -478,10 +482,14 @@ static int hook_plugin_unload_common(int argc, const char *const *argv) {
 		struct CPlugin **plugins = pluginhandler->plugins.m.mem;
 		if_hot (idx >= 0 && idx < pluginhandler->plugins.sz) {
 			const struct CPlugin *plugin = plugins[idx];
-			// XXX: *could* memoise the ispluginv1 call, but... meh. effort.
-			const struct CPlugin_common *common = ispluginv1(plugin) ?
-					&plugin->v1 : &plugin->v2;
-			if (common->theplugin == &plugin_obj) {
+			// XXX: *could* memoise the detect call somehow, but... meh. effort.
+			const void *theplugin;
+			switch_exhaust (detectpluginver(plugin)) {
+				case 1: theplugin = plugin->v1.theplugin; break;
+				case 2: theplugin = plugin->v2.theplugin; break;
+				case 3: theplugin = plugin->v3.theplugin;
+			}
+			if (theplugin == &plugin_obj) {
 				sst_userunloaded = true;
 				ownidx = idx;
 				return UNLOAD_SELF;
@@ -495,9 +503,20 @@ static int hook_plugin_unload_common(int argc, const char *const *argv) {
 	return UNLOAD_OTHER;
 }
 
-// TODO(compat): we'd have cbv1 here for OE. but we don't yet have the global
-// argc/argv access so there's no way to implement that.
-
+static void hook_plugin_unload_cbv1() {
+	extern int *_con_argc;
+	extern const char *(*_con_argv)[80];
+	int action = hook_plugin_unload_common(*_con_argc, *_con_argv);
+	switch_exhaust_enum(unload_action, action) {
+		case UNLOAD_SKIP:
+			return;
+		case UNLOAD_SELF:
+			tailcall orig_plugin_unload_cb.v1();
+		case UNLOAD_OTHER:
+			orig_plugin_unload_cb.v1();
+			EMIT_PluginUnloaded();
+	}
+}
 static void hook_plugin_unload_cbv2(const struct con_cmdargs *args) {
 	int action = hook_plugin_unload_common(args->argc, args->argv);
 	switch_exhaust_enum(unload_action, action) {
@@ -518,6 +537,7 @@ static bool do_load(ifacefactory enginef, ifacefactory serverf) {
 	}
 	factory_engine = enginef; factory_server = serverf;
 	if_cold (!engineapi_init(ifacever)) return false;
+	if (GAMETYPE_MATCHES(OE)) shuntvars(); // see also comment in con_detect()
 	const void **p = vtable_firstdiff;
 	if (GAMETYPE_MATCHES(Portal2)) *p++ = (void *)&nop_p_v; // ClientFullyConnect
 	*p++ = (void *)&nop_p_v;		  // ClientDisconnect
@@ -538,8 +558,12 @@ static bool do_load(ifacefactory enginef, ifacefactory serverf) {
 		hook_plugin_load_cb(cmd_plugin_load);
 		cmd_plugin_unload = con_findcmd("plugin_unload");
 		orig_plugin_unload_cb.v1 = cmd_plugin_unload->cb_v1; // n.b.: union!
-		// TODO(compat): detect OE/v1 and use that hook here when required
-		cmd_plugin_unload->cb_v2 = &hook_plugin_unload_cbv2;
+		if (GAMETYPE_MATCHES(OE)) {
+			cmd_plugin_unload->cb_v1 = &hook_plugin_unload_cbv1;
+		}
+		else {
+			cmd_plugin_unload->cb_v2 = &hook_plugin_unload_cbv2;
+		}
 	}
 	return true;
 }
@@ -553,12 +577,17 @@ static void do_unload() {
 		struct CPlugin **plugins = pluginhandler->plugins.m.mem;
 		// see comment in CPlugin struct. setting this to the real handle right
 		// before the engine tries to unload us allows it to actually do so. in
-		// newer branches this is redundant but doesn't do any harm so it's just
-		// unconditional (for v1). NOTE: old engines ALSO just leak the handle
-		// and never call Unload() if Load() fails; can't really do anything
-		// about that.
+		// some newer branches still on v2 this is redundant but doesn't do any
+		// harm so it's just unconditional for simplicity. in v3 it's totally
+		// unnecessary so we skip it.. NOTE: older engines ALSO just leak the
+		// handle and never call Unload() if Load() fails; can't really do
+		// anything about that though.
 		struct CPlugin *plugin = plugins[ownidx];
-		if (ispluginv1(plugin)) plugins[ownidx]->v1.module = ownhandle();
+		switch_exhaust (detectpluginver(plugin)) {
+			case 1: plugin->v1.module = ownhandle(); break;
+			case 2: plugin->v2.module = ownhandle(); break;
+			case 3:;
+		}
 #endif
 	}
 	endfeatures();