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/*
* Copyright © 2024 Michael Smith <mikesmiffy128@gmail.com>
* Copyright © 2024 Willian Henrique <wsimanbrazil@yahoo.com.br>
*
* 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 "abi.h"
#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"
#include "x86.h"
FEATURE()
IMPORT void *KeyValuesSystem(void); // vstlib symbol
static void *kvs;
static int vtidx_GetSymbolForString = 3, vtidx_GetStringForSymbol = 4;
static bool iskvv2 = false;
DECL_VFUNC_DYN(int, GetSymbolForString, const char *, bool)
DECL_VFUNC_DYN(const char *, GetStringForSymbol, 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 = iskvv2 ? kv->v2.child : kv->v1.child; kv;
kv = iskvv2 ? kv->v2.next : kv->v1.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(const struct KeyValues *kv) { return kv->strval; }
void kvsys_free(struct KeyValues *kv) {
while (kv) {
kvsys_free(iskvv2 ? kv->v2.child : kv->v1.child);
struct KeyValues *next = iskvv2 ? kv->v2.next : kv->v1.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 string that gameui won't match.
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;
}
static void detectabichange(void **kvsvt) {
// When no virtual destructor is present, the 6th function in the KVS vtable
// is AddKeyValuesToMemoryLeakList, which is a nop in release builds.
// L4D2 2.2.3.8 (14th May 2024) adds a virtual destructor which pushes
// everything down, so the 6th function is not a nop any more. This
// coincides with changes to the KeyValues struct layout (see above).
uchar *insns = kvsvt[5];
// should be RETI16 on Windows (thiscall, callee cleanup) and RET on Linux
// (cdecl, caller cleanup) but let's just check both to be thorough
if (insns[0] != X86_RETI16 && insns[0] != X86_RET) {
iskvv2 = true;
vtidx_GetSymbolForString += NVDTOR;
vtidx_GetStringForSymbol += NVDTOR;
}
}
INIT {
kvs = KeyValuesSystem();
// NOTE: this hook is technically redundant for early versions but I CBA
// writing a version check; it's easier to just do this unilaterally. The
// kvs ABI check is probably relevant for other games, but none that we
// currently actively support
if (GAMETYPE_MATCHES(L4D2x)) {
void **kvsvt = mem_loadptr(kvs);
detectabichange(kvsvt);
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, vtidx_GetStringForSymbol,
(void *)orig_GetStringForSymbol);
}
}
// vi: sw=4 ts=4 noet tw=80 cc=80
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