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/*
* Copyright © 2021 Willian Henrique <wsimanbrazil@yahoo.com.br>
* 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 <string.h>
#include "con_.h"
#include "engineapi.h"
#include "errmsg.h"
#include "feature.h"
#include "gamedata.h"
#include "gameinfo.h"
#include "hook.h"
#include "intdefs.h"
#include "mem.h"
#include "os.h"
#include "ppmagic.h"
#include "vcall.h"
#include "x86.h"
#include "x86util.h"
FEATURE("improved demo recording")
REQUIRE_GAMEDATA(vtidx_StopRecording)
DEF_CVAR(sst_autorecord, "Continuously record demos even after reconnecting", 1,
CON_ARCHIVE | CON_HIDDEN)
void *demorecorder;
static int *demonum;
static bool *recording;
static bool wantstop = false;
#define SIGNONSTATE_NEW 3
#define SIGNONSTATE_SPAWN 5
#define SIGNONSTATE_FULL 6
typedef void (*VCALLCONV SetSignonState_func)(void *, int);
static SetSignonState_func orig_SetSignonState;
static void VCALLCONV hook_SetSignonState(void *this_, int state) {
struct CDemoRecorder *this = this_;
// NEW fires once every map or save load, but only bumps number if demo file
// was left open (i.e. every transition). bump it unconditionally instead!
if (state == SIGNONSTATE_NEW) {
int oldnum = *demonum;
orig_SetSignonState(this, state);
*demonum = oldnum + 1;
return;
}
// dumb hack: demo file gets opened on FULL. bumping the number on NEW would
// make the first demo number 2 so we set the number to 0 in the record
// command. however if we started recording already in-map we need to bodge
// it back up to 1 right before the demo actually gets created
if (state == SIGNONSTATE_FULL && *demonum == 0) *demonum = 1;
orig_SetSignonState(this, state);
}
typedef void (*VCALLCONV StopRecording_func)(void *);
static StopRecording_func orig_StopRecording;
static void VCALLCONV hook_StopRecording(void *this) {
// This can be called any number of times in a row, generally twice per load
// and once per explicit disconnect. Each time the engine sets demonum to 0
// and recording to false.
bool wasrecording = *recording;
int lastnum = *demonum;
orig_StopRecording(this);
// If the user didn't specifically request the stop, tell the engine to
// start recording again as soon as it can.
if (wasrecording && !wantstop && con_getvari(sst_autorecord)) {
*recording = true;
*demonum = lastnum;
}
}
static struct con_cmd *cmd_record, *cmd_stop;
static con_cmdcb orig_record_cb, orig_stop_cb;
static void hook_record_cb(const struct con_cmdargs *args) {
bool was = *recording;
if (!was && args->argc == 2 || args->argc == 3) {
// safety check: make sure a directory exists, otherwise recording
// silently fails. this is necessarily TOCTOU, but in practice it's
// way better than not doing it - just to have a sanity check.
const char *arg = args->argv[1];
const char *lastslash = 0;
for (const char *p = arg; *p; ++p) {
#ifdef _WIN32
if (*p == '/' || *p == '\\') lastslash = p;
#else
if (*p == '/') lastslash = p;
#endif
}
if (lastslash) {
int argdirlen = lastslash - arg;
int gdlen = os_strlen(gameinfo_gamedir);
if (gdlen + 1 + argdirlen < PATH_MAX) { // if not, too bad
os_char dir[PATH_MAX], *q = dir;
memcpy(q, gameinfo_gamedir, gdlen * sizeof(*gameinfo_gamedir));
q += gdlen;
*q++ = OS_LIT('/');
// ascii->wtf16 (probably turns into memcpy() on linux)
for (const char *p = arg; p - arg < argdirlen; ++p, ++q) {
*q = (uchar)*p;
}
q[argdirlen] = OS_LIT('\0');
// this is pretty ugly. the error cases would be way tidier if
// we could use open(O_DIRECTORY), but that's not a thing on
// windows, of course.
struct os_stat s;
static const char *const errpfx = "ERROR: can't record demo: ";
if (os_stat(dir, &s) == -1) {
if (errno == ENOENT) {
con_warn("%ssubdirectory %.*s doesn't exist\n", errpfx,
argdirlen, arg);
}
else {
con_warn("%s%s\n", errpfx, strerror(errno));
}
return;
}
if (!S_ISDIR(s.st_mode)) {
con_warn("%spath %.*s is not a directory\n", errpfx,
argdirlen, arg);
return;
}
}
}
}
orig_record_cb(args);
if (!was && *recording) {
*demonum = 0; // see SetSignonState comment above
// For UX, make it more obvious we're recording, in particular when not
// already in a map as the "recording to x.dem" won't come up yet.
// mike: I think this is questionably necessary but I'm outvoted :)
con_msg("Demo recording started\n");
}
}
static void hook_stop_cb(const struct con_cmdargs *args) {
wantstop = true;
orig_stop_cb(args);
wantstop = false;
}
// This finds the "demorecorder" global variable (the engine-wide CDemoRecorder
// instance).
static inline bool find_demorecorder(void) {
#ifdef _WIN32
// The "stop" command calls the virtual function demorecorder.IsRecording(),
// so just look for the load of the "this" pointer into ECX
for (uchar *p = (uchar *)orig_stop_cb; p - (uchar *)orig_stop_cb < 32;) {
if (p[0] == X86_MOVRMW && p[1] == X86_MODRM(0, 1, 5)) {
void **indirect = mem_loadptr(p + 2);
demorecorder = *indirect;
return true;
}
NEXT_INSN(p, "demorecorder object");
}
#else
#warning TODO(linux): implement linux equivalent (cdecl!)
#endif
return false;
}
// This finds "m_bRecording" and "m_nDemoNumber" using the pointer to the
// original "StopRecording" demorecorder function.
static inline bool find_recmembers(void *stoprecording) {
#ifdef _WIN32
for (uchar *p = (uchar *)stoprecording; p - (uchar *)stoprecording < 128;) {
// m_nDemoNumber = 0 -> mov dword ptr [<reg> + off], 0
// XXX: might end up wanting constants for the MRM field masks?
if (p[0] == X86_MOVMIW && (p[1] & 0xC0) == 0x80 &&
mem_load32(p + 6) == 0) {
demonum = mem_offset(demorecorder, mem_load32(p + 2));
}
// m_bRecording = false -> mov byte ptr [<reg> + off], 0
else if (p[0] == X86_MOVMI8 && (p[1] & 0xC0) == 0x80 && p[6] == 0) {
recording = mem_offset(demorecorder, mem_load32(p + 2));
}
if (recording && demonum) return true; // blegh
NEXT_INSN(p, "recording state variables");
}
#else // linux is probably different here idk
#warning TODO(linux): implement linux equivalent (???)
#endif
return false;
}
INIT {
cmd_record = con_findcmd("record");
if (!cmd_record) { // can *this* even happen? I hope not!
errmsg_errorx("couldn't find \"record\" command");
return false;
}
orig_record_cb = con_getcmdcb(cmd_record);
cmd_stop = con_findcmd("stop");
if (!cmd_stop) {
errmsg_errorx("couldn't find \"stop\" command");
return false;
}
orig_stop_cb = con_getcmdcb(cmd_stop);
if (!find_demorecorder()) {
errmsg_errorx("couldn't find demo recorder instance");
return false;
}
void **vtable = *(void ***)demorecorder;
// XXX: 16 is totally arbitrary here! figure out proper bounds later
if (!os_mprot(vtable, 16 * sizeof(void *), PAGE_READWRITE)) {
errmsg_errorsys("couldn't make virtual table writable");
return false;
}
if (!find_recmembers(vtable[vtidx_StopRecording])) {
errmsg_errorx("couldn't find recording state variables");
return false;
}
orig_SetSignonState = (SetSignonState_func)hook_vtable(vtable,
vtidx_SetSignonState, (void *)&hook_SetSignonState);
orig_StopRecording = (StopRecording_func)hook_vtable(vtable,
vtidx_StopRecording, (void *)&hook_StopRecording);
cmd_record->cb = &hook_record_cb;
cmd_stop->cb = &hook_stop_cb;
sst_autorecord->base.flags &= ~CON_HIDDEN;
return true;
}
END {
// avoid dumb edge case if someone somehow records and immediately unloads
if (*recording && *demonum == 0) *demonum = 1;
void **vtable = *(void ***)demorecorder;
unhook_vtable(vtable, vtidx_SetSignonState, (void *)orig_SetSignonState);
unhook_vtable(vtable, vtidx_StopRecording, (void *)orig_StopRecording);
cmd_record->cb = orig_record_cb;
cmd_stop->cb = orig_stop_cb;
}
// vi: sw=4 ts=4 noet tw=80 cc=80
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