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/*
* Copyright © 2024 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 "dictmaptree.h"
#include "engineapi.h"
#include "errmsg.h"
#include "feature.h"
#include "gamedata.h"
#include "gametype.h"
#include "intdefs.h"
#include "langext.h"
#include "mem.h"
#include "vcall.h"
#include "x86.h"
#include "x86util.h"
FEATURE()
DECL_VFUNC_DYN(void *, PEntityOfEntIndex, int)
static struct edict **edicts = 0;
struct edict *ent_getedict(int idx) {
if (edicts) {
// globalvars->edicts seems to be null when disconnected
if_hot (*edicts) return mem_offset(*edicts, sz_edict * idx);
return 0;
}
else {
return PEntityOfEntIndex(engserver, idx);
}
}
void *ent_get(int idx) {
struct edict *e = ent_getedict(idx);
if_hot(e) return e->ent_unknown;
return 0;
}
struct CEntityFactory {
struct CEntityFactory_vtable {
void /*IServerNetworkable*/ *(*VCALLCONV Create)(
struct CEntityFactory *this, const char *name);
void (*VCALLCONV Destroy)(struct CEntityFactory *this,
void /*IServerNetworkable*/ *networkable);
usize (*VCALLCONV GetEntitySize)(struct CEntityFactory *this);
} *vtable;
};
struct CEntityFactoryDictionary {
void **vtable;
struct CUtlDict_p_ushort dict;
};
#ifdef _WIN32 // TODO(linux): this'll be different too, leaving out for now
static struct CEntityFactoryDictionary *entfactorydict = 0;
static inline bool find_entfactorydict(con_cmdcb dumpentityfactories_cb) {
const uchar *insns = (const uchar *)dumpentityfactories_cb;
for (const uchar *p = insns; p - insns < 64;) {
// EntityFactoryDictionary() is inlined, and returns a static, which is
// lazy-inited (trivia: this was old MSVC, so it's not thread-safe like
// C++ requires nowadays). for some reason the init flag is set using
// OR, and then the instance is put in ECX to call the ctor
if (p[0] == X86_ORMRW && p[6] == X86_MOVECXI && p[11] == X86_CALL) {
entfactorydict = mem_loadptr(p + 7);
return true;
}
NEXT_INSN(p, "entity factory dictionary");
}
return false;
}
#endif
const struct CEntityFactory *ent_getfactory(const char *name) {
#ifdef _WIN32
if (entfactorydict) {
return CUtlDict_p_ushort_findval(&entfactorydict->dict, name);
}
#endif
return 0;
}
typedef void (*VCALLCONV ctor_func)(void *);
static inline ctor_func findctor(const struct CEntityFactory *factory,
const char *classname) {
#ifdef _WIN32
const uchar *insns = (const uchar *)factory->vtable->Create;
// mostly every Create() method follows the same pattern. after calling what
// is presumably operator new(), it copies the return value from a register
// into ECX and then calls the constructor.
//
// there have also been some thunky-looking ones, which we attempt to
// resolve by following the first call if we bump into a ret before anything
// else. this is depth-limited to prevent things getting out of hand.
const uchar *seencall = 0;
int depth = 3;
for (const uchar *p = insns; p - insns < 32;) {
if (!seencall && p[0] == X86_CALL) {
seencall = p;
}
else {
if (p[0] == X86_MOVRMW && (p[1] & 0xF8) == 0xC8
&& p[2] == X86_CALL) {
return (ctor_func)(p + 7 + mem_loads32(p + 3));
}
if (p[0] == X86_RET || p[0] == X86_RETI16) {
if (seencall && --depth) {
p = seencall + 5 + mem_loads32(seencall + 1); insns = p;
seencall = 0;
continue;
}
return false;
}
}
// duping NEXT_INSN macro here in the name of a nicer message
int len = x86_len(p);
if (len == -1) {
errmsg_errorx("unknown or invalid instruction looking for %s "
"constructor", classname);
return 0;
}
p += len;
}
#else
#warning TODO(linux): this will be different of course
#endif
return 0;
}
void **ent_findvtable(const struct CEntityFactory *factory,
const char *classname) {
#ifdef _WIN32
ctor_func ctor = findctor(factory, classname);
if_cold (!ctor) return 0;
const uchar *insns = (const uchar *)ctor;
// the constructor itself should do *(void**)this = &vtable; almost right
// away, so look for the first immediate load into indirect register
for (const uchar *p = insns; p - insns < 32;) {
if (p[0] == X86_MOVMIW && (p[1] & 0xF8) == 0) return mem_loadptr(p + 2);
int len = x86_len(p);
if_cold (len == -1) {
errmsg_errorx("unknown or invalid instruction looking for %s "
"vtable pointer", classname);
return 0;
}
p += len;
}
#else
#warning TODO(linux): this will be different of course
#endif
return 0;
}
INIT {
#ifdef _WIN32 // TODO(linux): above
struct con_cmd *dumpentityfactories = con_findcmd("dumpentityfactories");
if_cold (!dumpentityfactories ||
!find_entfactorydict(dumpentityfactories->cb)) {
errmsg_warnx("server entity factories unavailable");
}
#endif
// for PEntityOfEntIndex we don't really have to do any more init, we
// can just call the function later.
if (has_vtidx_PEntityOfEntIndex) return true;
if (globalvars && has_off_edicts) {
edicts = mem_offset(globalvars, off_edicts);
return true;
}
errmsg_warnx("not implemented for this engine");
return false;
}
// vi: sw=4 ts=4 noet tw=80 cc=80
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