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/*
* Copyright © 2023 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 "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 (!*edicts) return 0;
return mem_offset(*edicts, sz_edict * idx);
}
else {
return PEntityOfEntIndex(engserver, idx);
}
}
void *ent_get(int idx) {
struct edict *e = ent_getedict(idx);
if (!e) return 0;
return e->ent_unknown;
}
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;) {
// the call to EntityFactoryDictionary() is inlined. that returns a
// static, which is lazy-inited (trivia: this was old MSVC, so it's not
// threadsafe 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;
// every Create() method follows the same pattern. after calling what is
// presumably operator new(), it copies the return value from EAX into ECX
// and then calls the constructor.
for (const uchar *p = insns; p - insns < 32;) {
if (p[0] == X86_MOVRMW && p[1] == 0xC8 && p[2] == X86_CALL) {
return (ctor_func)(p + 7 + mem_loadoffset(p + 3));
}
// 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 (!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 < 24;) {
if (p[0] == X86_MOVMIW && (p[1] & 0xF8) == 0) return mem_loadptr(p + 2);
int len = x86_len(p);
if (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 (!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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