/* * Copyright © 2024 Michael Smith * Copyright © 2024 Willian Henrique * * 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 "langext.h" #include "mem.h" #include "os.h" #include "vcall.h" #include "x86.h" FEATURE() 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_cold (!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