Add type-safety to virtual calls and accessors

This probably should have been the design from the start.

It's still possible to use void pointers, and this is done in a couple
of places for simplicity, but wherever possible, we have actual structs
for things now.

Additionally, in places where vtables are fiddled with, e.g. vtable
hooks, we have actual struct definitions with vtable pointers so there's
need for pointer-casting horror.

1 files changed, 18 insertions, 19 deletions

diff --git a/src/inputhud.c b/src/inputhud.c
index 4e332c4..fdefe6a 100644
--- a/src/inputhud.c
+++ b/src/inputhud.c
@@ -61,7 +61,7 @@ DEF_FEAT_CVAR_MINMAX(sst_inputhud_y,
 		"Input HUD y position (fraction between screen top and bottom)",
 		0.95, 0, 1, CON_ARCHIVE)
 
-static void *input;
+static struct CInput { void **vtable; } *input;
 static int heldbuttons = 0, tappedbuttons = 0;
 
 static struct rgba colours[3] = {
@@ -98,8 +98,8 @@ struct CUserCmd {
 };
 
 #define vtidx_GetUserCmd_l4dbased vtidx_GetUserCmd
-DECL_VFUNC_DYN(struct CUserCmd *, GetUserCmd, int)
-DECL_VFUNC_DYN(struct CUserCmd *, GetUserCmd_l4dbased, int, int)
+DECL_VFUNC_DYN(struct CInput, struct CUserCmd *, GetUserCmd, int)
+DECL_VFUNC_DYN(struct CInput, struct CUserCmd *, GetUserCmd_l4dbased, int, int)
 
 typedef void (*VCALLCONV CreateMove_func)(void *, int, float, bool);
 static CreateMove_func orig_CreateMove;
@@ -114,16 +114,17 @@ static void VCALLCONV hook_CreateMove(void *this, int seq, float ft,
 	if (cmd) { heldbuttons = cmd->buttons; tappedbuttons |= cmd->buttons; }
 }
 // basically a dupe, but calling the other version of GetUserCmd
-static void VCALLCONV hook_CreateMove_l4dbased(void *this, int seq, float ft,
-		bool active) {
+static void VCALLCONV hook_CreateMove_l4dbased(struct CInput *this, int seq,
+		float ft, bool active) {
 	orig_CreateMove(this, seq, ft, active);
 	struct CUserCmd *cmd = GetUserCmd_l4dbased(this, -1, seq);
 	if (cmd) { heldbuttons = cmd->buttons; tappedbuttons |= cmd->buttons; }
 }
 
-typedef void (*VCALLCONV DecodeUserCmdFromBuffer_func)(void *, void *, int);
-typedef void (*VCALLCONV DecodeUserCmdFromBuffer_l4dbased_func)(void *, int,
+typedef void (*VCALLCONV DecodeUserCmdFromBuffer_func)(struct CInput *,
 		void *, int);
+typedef void (*VCALLCONV DecodeUserCmdFromBuffer_l4dbased_func)(struct CInput *,
+		int, void *, int);
 static union {
 	DecodeUserCmdFromBuffer_func prel4d;
 	DecodeUserCmdFromBuffer_l4dbased_func l4dbased;
@@ -131,13 +132,13 @@ static union {
 #define orig_DecodeUserCmdFromBuffer _orig_DecodeUserCmdFromBuffer.prel4d
 #define orig_DecodeUserCmdFromBuffer_l4dbased \
 		_orig_DecodeUserCmdFromBuffer.l4dbased
-static void VCALLCONV hook_DecodeUserCmdFromBuffer(void *this, void *reader,
-		int seq) {
+static void VCALLCONV hook_DecodeUserCmdFromBuffer(struct CInput *this,
+		void *reader, int seq) {
 	orig_DecodeUserCmdFromBuffer(this, reader, seq);
 	struct CUserCmd *cmd = GetUserCmd(this, seq);
 	if (cmd) { heldbuttons = cmd->buttons; tappedbuttons |= cmd->buttons; }
 }
-static void VCALLCONV hook_DecodeUserCmdFromBuffer_l4dbased(void *this,
+static void VCALLCONV hook_DecodeUserCmdFromBuffer_l4dbased(struct CInput *this,
 		int slot, void *reader, int seq) {
 	orig_DecodeUserCmdFromBuffer_l4dbased(this, slot, reader, seq);
 	struct CUserCmd *cmd = GetUserCmd_l4dbased(this, slot, seq);
@@ -366,13 +367,12 @@ HANDLE_EVENT(HudPaint, int screenw, int screenh) {
 }
 
 // find the CInput "input" global
-static inline bool find_input(void* vclient) {
+static inline bool find_input(struct VClient *vclient) {
 #ifdef _WIN32
 	// the only CHLClient::DecodeUserCmdFromBuffer() does is call a virtual
 	// function, so find its thisptr being loaded into ECX
-	void* decodeusercmd =
-		(*(void***)vclient)[vtidx_VClient_DecodeUserCmdFromBuffer];
-	for (uchar *p = (uchar *)decodeusercmd; p - (uchar *)decodeusercmd < 32;) {
+	uchar *insns = vclient->vtable[vtidx_VClient_DecodeUserCmdFromBuffer];
+	for (uchar *p = insns; p - insns < 32;) {
 		if (p[0] == X86_MOVRMW && p[1] == X86_MODRM(0, 1, 5)) {
 			void **indirect = mem_loadptr(p + 2);
 			input = *indirect;
@@ -387,7 +387,7 @@ static inline bool find_input(void* vclient) {
 }
 
 INIT {
-	void *vclient;
+	struct VClient *vclient;
 	if (!(vclient = factory_client("VClient015", 0)) &&
 			!(vclient = factory_client("VClient016", 0)) &&
 			!(vclient = factory_client("VClient017", 0))) {
@@ -398,7 +398,7 @@ INIT {
 		errmsg_errorx("couldn't find input global");
 		return FEAT_INCOMPAT;
 	}
-	void **vtable = mem_loadptr(input);
+	void **vtable = input->vtable;
 	// just unprotect the first few pointers (GetUserCmd is 8)
 	if_cold (!os_mprot(vtable, sizeof(void *) * 8, PAGE_READWRITE)) {
 		errmsg_errorsys("couldn't make virtual table writable");
@@ -446,11 +446,10 @@ INIT {
 }
 
 END {
-	void **vtable = mem_loadptr(input);
-	unhook_vtable(vtable, vtidx_CreateMove, (void *)orig_CreateMove);
+	unhook_vtable(input->vtable, vtidx_CreateMove, (void *)orig_CreateMove);
 	// N.B.: since the orig_ function is in a union, we don't have to worry
 	// about which version we're unhooking
-	unhook_vtable(vtable, vtidx_DecodeUserCmdFromBuffer,
+	unhook_vtable(input->vtable, vtidx_DecodeUserCmdFromBuffer,
 			(void *)orig_DecodeUserCmdFromBuffer);
 }