1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
|
/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#include "sword25/util/lua_serialization.h"
#include "sword25/util/double_serializer.h"
#include "sword25/util/lua_serialization_util.h"
#include "common/stream.h"
#include "lua/lobject.h"
#include "lua/lstate.h"
#include "lua/lgc.h"
namespace Lua {
#define PERMANENT_TYPE 101
struct SerializationInfo {
lua_State *luaState;
Common::WriteStream *writeStream;
uint counter;
};
static void serialize(SerializationInfo *info);
static void serializeBoolean(SerializationInfo *info);
static void serializeNumber(SerializationInfo *info);
static void serializeString(SerializationInfo *info);
static void serializeTable(SerializationInfo *info);
static void serializeFunction(SerializationInfo *info);
static void serializeThread(SerializationInfo *info);
static void serializeProto(SerializationInfo *info);
static void serializeUpValue(SerializationInfo *info);
static void serializeUserData(SerializationInfo *info);
void serializeLua(lua_State *luaState, Common::WriteStream *writeStream) {
SerializationInfo info;
info.luaState = luaState;
info.writeStream = writeStream;
info.counter = 0u;
// The process starts with the lua stack as follows:
// >>>>> permTbl rootObj
// That's the table of permanents and the root object to be serialized
// Make sure there is enough room on the stack
lua_checkstack(luaState, 4);
assert(lua_gettop(luaState) == 2);
// And that the root isn't nil
assert(!lua_isnil(luaState, 2));
// Create a table to hold indexes of everything that's serialized
// This allows us to only serialize an object once
// Every other time, just reference the index
lua_newtable(luaState);
// >>>>> permTbl rootObj indexTbl
// Now we're going to make the table weakly keyed. This prevents the
// GC from visiting it and trying to mark things it doesn't want to
// mark in tables, e.g. upvalues. All objects in the table are
// a priori reachable, so it doesn't matter that we do this.
// Create the metatable
lua_newtable(luaState);
// >>>>> permTbl rootObj indexTbl metaTbl
lua_pushstring(luaState, "__mode");
// >>>>> permTbl rootObj indexTbl metaTbl "__mode"
lua_pushstring(luaState, "k");
// >>>>> permTbl rootObj indexTbl metaTbl "__mode" "k"
lua_settable(luaState, 4);
// >>>>> permTbl rootObj indexTbl metaTbl
lua_setmetatable(luaState, 3);
// >>>>> permTbl rootObj indexTbl
// Swap the indexTable and the rootObj
lua_insert(luaState, 2);
// >>>>> permTbl indexTbl rootObj
// Serialize the root recursively
serialize(&info);
// Return the stack back to the original state
lua_remove(luaState, 2);
// >>>>> permTbl rootObj
}
static void serialize(SerializationInfo *info) {
// The stack can potentially have many things on it
// The object we want to serialize is the item on the top of the stack
// >>>>> permTbl indexTbl rootObj ...... obj
// Make sure there is enough room on the stack
lua_checkstack(info->luaState, 2);
// If the object has already been written, don't write it again
// Instead write the index of the object from the indexTbl
// Check the indexTbl
lua_pushvalue(info->luaState, -1);
// >>>>> permTbl indexTbl rootObj ...... obj obj
lua_rawget(info->luaState, 2);
// >>>>> permTbl indexTbl rootObj ...... obj ?index?
// If the index isn't nil, the object has already been written
if (!lua_isnil(info->luaState, -1)) {
// Write out a flag that indicates that it's an index
info->writeStream->writeByte(0);
// Retrieve the index from the stack
uint *index = (uint *)lua_touserdata(info->luaState, -1);
// Write out the index
info->writeStream->writeUint32LE(*index);
// Pop the index off the stack
lua_pop(info->luaState, 1);
return;
}
// Pop the nil off the stack
lua_pop(info->luaState, 1);
// Write out a flag that indicates that this is a real object
info->writeStream->writeByte(1);
// If the object itself is nil, then write out a zero as a placeholder
if (lua_isnil(info->luaState, -1)) {
info->writeStream->writeByte(0);
return;
}
// Add the object to the indexTbl
lua_pushvalue(info->luaState, -1);
// >>>>> permTbl indexTbl rootObj ...... obj obj
uint *ref = (uint *)lua_newuserdata(info->luaState, sizeof(uint));
*ref = ++(info->counter);
// >>>>> permTbl indexTbl rootObj ...... obj obj index
lua_rawset(info->luaState, 2);
// >>>>> permTbl indexTbl rootObj ...... obj
// Write out the index
info->writeStream->writeUint32LE(info->counter);
// Objects that are in the permanents table are serialized in a special way
lua_pushvalue(info->luaState, -1);
// >>>>> permTbl indexTbl rootObj ...... obj obj
lua_gettable(info->luaState, 1);
// >>>>> permTbl indexTbl rootObj ...... obj obj ?permKey?
if (!lua_isnil(info->luaState, -1)) {
// Write out the type
info->writeStream->writeSint32LE(PERMANENT_TYPE);
// Serialize the key
serialize(info);
// Pop the key off the stack
lua_pop(info->luaState, 1);
return;
}
// Pop the nil off the stack
lua_pop(info->luaState, 1);
// Query the type of the object
int objType = lua_type(info->luaState, -1);
// Write it out
info->writeStream->writeSint32LE(objType);
// Serialize the object by its type
switch (objType) {
case LUA_TBOOLEAN:
serializeBoolean(info);
break;
case LUA_TLIGHTUSERDATA:
// You can't serialize a pointer
// It would be meaningless on the next run
assert(0);
break;
case LUA_TNUMBER:
serializeNumber(info);
break;
case LUA_TSTRING:
serializeString(info);
break;
case LUA_TTABLE:
serializeTable(info);
break;
case LUA_TFUNCTION:
serializeFunction(info);
break;
case LUA_TTHREAD:
serializeThread(info);
break;
case LUA_TPROTO:
serializeProto(info);
break;
case LUA_TUPVAL:
serializeUpValue(info);
break;
case LUA_TUSERDATA:
serializeUserData(info);
break;
default:
assert(0);
}
}
static void serializeBoolean(SerializationInfo *info) {
int value = lua_toboolean(info->luaState, -1);
info->writeStream->writeSint32LE(value);
}
static void serializeNumber(SerializationInfo *info) {
lua_Number value = lua_tonumber(info->luaState, -1);
#if 1
Util::SerializedDouble serializedValue(Util::encodeDouble(value));
info->writeStream->writeUint32LE(serializedValue.significandOne);
info->writeStream->writeUint32LE(serializedValue.signAndSignificandTwo);
info->writeStream->writeSint16LE(serializedValue.exponent);
#else
// NOTE: We need to store a double. Unfortunately, we have to accommodate endianness.
// Also, I don't know if we can assume all compilers use IEEE double
// Therefore, I have chosen to store the double as a string.
Common::String buffer = Common::String::format("%f", value);
info->writeStream->write(buffer.c_str(), buffer.size());
#endif
}
static void serializeString(SerializationInfo *info) {
// Hard cast to a uint32 to force size_t to an explicit size
// *Theoretically* this could truncate, but if we have a 4gb string, we have bigger problems
uint32 length = static_cast<uint32>(lua_strlen(info->luaState, -1));
info->writeStream->writeUint32LE(length);
const char *str = lua_tostring(info->luaState, -1);
info->writeStream->write(str, length);
}
/* Choose whether to do a regular or special persistence based on an object's
* metatable. "default" is whether the object, if it doesn't have a __persist
* entry, is literally persistable or not.
* Pushes the unpersist closure and returns true if special persistence is
* used. */
static bool serializeSpecialObject(SerializationInfo *info, bool defaction) {
// Make sure there is enough room on the stack
lua_checkstack(info->luaState, 4);
// Check whether we should persist literally, or via the __persist metafunction
if (!lua_getmetatable(info->luaState, -1)) {
if (defaction) {
// Write out a flag declaring that the object isn't special and should be persisted normally
info->writeStream->writeSint32LE(0);
return false;
} else {
lua_pushstring(info->luaState, "Type not literally persistable by default");
lua_error(info->luaState);
return false; // Not reached
}
}
// >>>>> permTbl indexTbl ...... obj metaTbl
lua_pushstring(info->luaState, "__persist");
// >>>>> permTbl indexTbl rootObj ...... obj metaTbl "__persist"
lua_rawget(info->luaState, -2);
// >>>>> permTbl indexTbl ...... obj metaTbl ?__persist?
if (lua_isnil(info->luaState, -1)) {
// >>>>> permTbl indexTbl ...... obj metaTbl nil
lua_pop(info->luaState, 2);
// >>>>> permTbl indexTbl ...... obj
if (defaction) {
// Write out a flag declaring that the object isn't special and should be persisted normally
info->writeStream->writeSint32LE(0);
return false;
} else {
lua_pushstring(info->luaState, "Type not literally persistable by default");
lua_error(info->luaState);
return false; // Return false
}
} else if (lua_isboolean(info->luaState, -1)) {
// >>>>> permTbl indexTbl ...... obj metaTbl bool
if (lua_toboolean(info->luaState, -1)) {
// Write out a flag declaring that the object isn't special and should be persisted normally
info->writeStream->writeSint32LE(0);
// >>>>> permTbl indexTbl ...... obj metaTbl true */
lua_pop(info->luaState, 2);
// >>>>> permTbl indexTbl ...... obj
return false;
} else {
lua_pushstring(info->luaState, "Metatable forbade persistence");
lua_error(info->luaState);
return false; // Not reached
}
} else if (!lua_isfunction(info->luaState, -1)) {
lua_pushstring(info->luaState, "__persist not nil, boolean, or function");
lua_error(info->luaState);
}
// >>>>> permTbl indexTbl ...... obj metaTbl __persist
lua_pushvalue(info->luaState, -3);
// >>>>> permTbl indexTbl ...... obj metaTbl __persist obj
// >>>>> permTbl indexTbl ...... obj metaTbl ?func?
if (!lua_isfunction(info->luaState, -1)) {
lua_pushstring(info->luaState, "__persist function did not return a function");
lua_error(info->luaState);
}
// >>>>> permTbl indexTbl ...... obj metaTbl func
// Write out a flag that the function exists
info->writeStream->writeSint32LE(1);
// Serialize the function
serialize(info);
lua_pop(info->luaState, 2);
// >>>>> permTbl indexTbl ...... obj
return true;
}
static void serializeTable(SerializationInfo *info) {
// >>>>> permTbl indexTbl ...... tbl
// Make sure there is enough room on the stack
lua_checkstack(info->luaState, 3);
// Test if the object needs special serialization
if (serializeSpecialObject(info, 1)) {
return;
}
// >>>>> permTbl indexTbl ...... tbl
// First, serialize the metatable (if any)
if (!lua_getmetatable(info->luaState, -1)) {
lua_pushnil(info->luaState);
}
// >>>>> permTbl indexTbl ...... tbl metaTbl/nil */
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... tbl
lua_pushnil(info->luaState);
// >>>>> permTbl indexTbl ...... tbl nil
// Now, persist all k/v pairs
while (lua_next(info->luaState, -2)) {
// >>>>> permTbl indexTbl ...... tbl k v */
lua_pushvalue(info->luaState, -2);
// >>>>> permTbl indexTbl ...... tbl k v k */
// Serialize the key
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... tbl k v */
// Serialize the value
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... tbl k */
}
// >>>>> permTbl indexTbl ...... tbl
// Terminate the list with a nil
lua_pushnil(info->luaState);
// >>>>> permTbl indexTbl ...... tbl
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... tbl
}
static void serializeFunction(SerializationInfo *info) {
// >>>>> permTbl indexTbl ...... func
Closure *cl = clvalue(getObject(info->luaState, -1));
lua_checkstack(info->luaState, 2);
if (cl->c.isC) {
/* It's a C function. For now, we aren't going to allow
* persistence of C closures, even if the "C proto" is
* already in the permanents table. */
lua_pushstring(info->luaState, "Attempt to persist a C function");
lua_error(info->luaState);
} else {
// It's a Lua closure
// We don't really _NEED_ the number of upvals, but it'll simplify things a bit
info->writeStream->writeByte(cl->l.p->nups);
// Serialize the prototype
pushProto(info->luaState, cl->l.p);
// >>>>> permTbl indexTbl ...... func proto */
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... func
// Serialize upvalue values (not the upvalue objects themselves)
for (byte i = 0; i < cl->l.p->nups; i++) {
// >>>>> permTbl indexTbl ...... func
pushUpValue(info->luaState, cl->l.upvals[i]);
// >>>>> permTbl indexTbl ...... func upval
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... func
}
// >>>>> permTbl indexTbl ...... func
// Serialize function environment
lua_getfenv(info->luaState, -1);
// >>>>> permTbl indexTbl ...... func fenv
if (lua_equal(info->luaState, -1, LUA_GLOBALSINDEX)) {
// Function has the default fenv
// >>>>> permTbl indexTbl ...... func _G
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... func
lua_pushnil(info->luaState);
// >>>>> permTbl indexTbl ...... func nil
}
// >>>>> permTbl indexTbl ...... func fenv/nil
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... func
}
}
static void serializeThread(SerializationInfo *info) {
// >>>>> permTbl indexTbl ...... thread
lua_State *threadState = lua_tothread(info->luaState, -1);
// Make sure there is enough room on the stack
lua_checkstack(info->luaState, threadState->top - threadState->stack + 1);
if (info->luaState == threadState) {
lua_pushstring(info->luaState, "Can't persist currently running thread");
lua_error(info->luaState);
return; /* not reached */
}
// Persist the stack
// We *could* have truncation here, but if we have more than 4 billion items on a stack, we have bigger problems
uint32 stackSize = static_cast<uint32>(appendStackToStack_reverse(threadState, info->luaState));
info->writeStream->writeUint32LE(stackSize);
// >>>>> permTbl indexTbl ...... thread (reversed contents of thread stack) */
for (; stackSize > 0; --stackSize) {
serialize(info);
lua_pop(info->luaState, 1);
}
// >>>>> permTbl indexTbl ...... thread
// Now, serialize the CallInfo stack
// Again, we *could* have truncation here, but if we have more than 4 billion items on a stack, we have bigger problems
uint32 numFrames = static_cast<uint32>((threadState->ci - threadState->base_ci) + 1);
info->writeStream->writeUint32LE(numFrames);
for (uint32 i = 0; i < numFrames; i++) {
CallInfo *ci = threadState->base_ci + i;
// Same argument as above about truncation
uint32 stackBase = static_cast<uint32>(ci->base - threadState->stack);
uint32 stackFunc = static_cast<uint32>(ci->func - threadState->stack);
uint32 stackTop = static_cast<uint32>(ci->top - threadState->stack);
info->writeStream->writeUint32LE(stackBase);
info->writeStream->writeUint32LE(stackFunc);
info->writeStream->writeUint32LE(stackTop);
info->writeStream->writeSint32LE(ci->nresults);
uint32 savedpc = (ci != threadState->base_ci) ? static_cast<uint32>(ci->savedpc - ci_func(ci)->l.p->code) : 0u;
info->writeStream->writeUint32LE(savedpc);
}
// Serialize the state's other parameters, with the exception of upval stuff
assert(threadState->nCcalls <= 1);
info->writeStream->writeByte(threadState->status);
// Same argument as above about truncation
uint32 stackBase = static_cast<uint32>(threadState->base - threadState->stack);
uint32 stackFunc = static_cast<uint32>(threadState->top - threadState->stack);
info->writeStream->writeUint32LE(stackBase);
info->writeStream->writeUint32LE(stackFunc);
// Same argument as above about truncation
uint32 stackOffset = static_cast<uint32>(threadState->errfunc);
info->writeStream->writeUint32LE(stackOffset);
// Finally, record upvalues which need to be reopened
// See the comment above serializeUpVal() for why we do this
UpVal *upVal;
// >>>>> permTbl indexTbl ...... thread
for (GCObject *gcObject = threadState->openupval; gcObject != NULL; gcObject = upVal->next) {
upVal = gco2uv(gcObject);
/* Make sure upvalue is really open */
assert(upVal->v != &upVal->u.value);
pushUpValue(info->luaState, upVal);
// >>>>> permTbl indexTbl ...... thread upVal
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... thread
// Same argument as above about truncation
uint32 stackpos = static_cast<uint32>(upVal->v - threadState->stack);
info->writeStream->writeUint32LE(stackpos);
}
// >>>>> permTbl indexTbl ...... thread
lua_pushnil(info->luaState);
// >>>>> permTbl indexTbl ...... thread nil
// Use nil as a terminator
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... thread
}
static void serializeProto(SerializationInfo *info) {
// >>>>> permTbl indexTbl ...... proto
Proto *proto = gco2p(getObject(info->luaState, -1)->value.gc);
// Make sure there is enough room on the stack
lua_checkstack(info->luaState, 2);
// Serialize constant refs */
info->writeStream->writeSint32LE(proto->sizek);
for (int i = 0; i < proto->sizek; ++i) {
pushObject(info->luaState, &proto->k[i]);
// >>>>> permTbl indexTbl ...... proto const
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... proto
}
// >>>>> permTbl indexTbl ...... proto
// Serialize inner Proto refs
info->writeStream->writeSint32LE(proto->sizep);
for (int i = 0; i < proto->sizep; ++i)
{
pushProto(info->luaState, proto->p[i]);
// >>>>> permTbl indexTbl ...... proto subProto */
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... proto
}
// >>>>> permTbl indexTbl ...... proto
// Serialize the code
info->writeStream->writeSint32LE(proto->sizecode);
uint32 len = static_cast<uint32>(sizeof(Instruction) * proto->sizecode);
info->writeStream->write(proto->code, len);
// Serialize upvalue names
info->writeStream->writeSint32LE(proto->sizeupvalues);
for (int i = 0; i < proto->sizeupvalues; ++i)
{
pushString(info->luaState, proto->upvalues[i]);
// >>>>> permTbl indexTbl ...... proto str
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... proto
}
// Serialize local variable infos
info->writeStream->writeSint32LE(proto->sizelocvars);
for (int i = 0; i < proto->sizelocvars; ++i) {
pushString(info->luaState, proto->locvars[i].varname);
// >>>>> permTbl indexTbl ...... proto str
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... proto
info->writeStream->writeSint32LE(proto->locvars[i].startpc);
info->writeStream->writeSint32LE(proto->locvars[i].endpc);
}
// Serialize source string
pushString(info->luaState, proto->source);
// >>>>> permTbl indexTbl ...... proto sourceStr
serialize(info);
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ...... proto
// Serialize line numbers
info->writeStream->writeSint32LE(proto->sizelineinfo);
if (proto->sizelineinfo) {
uint32 len = static_cast<uint32>(sizeof(int) * proto->sizelineinfo);
info->writeStream->write(proto->lineinfo, len);
}
// Serialize linedefined and lastlinedefined
info->writeStream->writeSint32LE(proto->linedefined);
info->writeStream->writeSint32LE(proto->lastlinedefined);
// Serialize misc values
info->writeStream->writeByte(proto->nups);
info->writeStream->writeByte(proto->numparams);
info->writeStream->writeByte(proto->is_vararg);
info->writeStream->writeByte(proto->maxstacksize);
}
/* Upvalues are tricky. Here's why.
*
* A particular upvalue may be either "open", in which case its member v
* points into a thread's stack, or "closed" in which case it points to the
* upvalue itself. An upvalue is closed under any of the following conditions:
* -- The function that initially declared the variable "local" returns
* -- The thread in which the closure was created is garbage collected
*
* To make things wackier, just because a thread is reachable by Lua doesn't
* mean it's in our root set. We need to be able to treat an open upvalue
* from an unreachable thread as a closed upvalue.
*
* The solution:
* (a) For the purposes of serializing, don't indicate whether an upvalue is
* closed or not.
* (b) When unserializing, pretend that all upvalues are closed.
* (c) When serializing, persist all open upvalues referenced by a thread
* that is persisted, and tag each one with the corresponding stack position
* (d) When unserializing, "reopen" each of these upvalues as the thread is
* unserialized
*/
static void serializeUpValue(SerializationInfo *info) {
// >>>>> permTbl indexTbl ...... upval
assert(ttype(getObject(info->luaState, -1)) == LUA_TUPVAL);
UpVal *upValue = gco2uv(getObject(info->luaState, -1)->value.gc);
// Make sure there is enough room on the stack
lua_checkstack(info->luaState, 1);
// We can't permit the upValue to linger around on the stack, as Lua
// will bail if its GC finds it.
lua_pop(info->luaState, 1);
// >>>>> permTbl indexTbl ......
pushObject(info->luaState, upValue->v);
// >>>>> permTbl indexTbl ...... obj
serialize(info);
// >>>>> permTbl indexTbl ...... obj
}
static void serializeUserData(SerializationInfo *info) {
// >>>>> permTbl rootObj ...... udata
// Make sure there is enough room on the stack
lua_checkstack(info->luaState, 2);
// Test if the object needs special serialization
if (serializeSpecialObject(info, 0)) {
return;
}
// Use literal persistence
// Hard cast to a uint32 length
// This could lead to truncation, but if we have a 4gb block of data, we have bigger problems
uint32 length = static_cast<uint32>(uvalue(getObject(info->luaState, -1))->len);
info->writeStream->writeUint32LE(length);
info->writeStream->write(lua_touserdata(info->luaState, -1), length);
// Serialize the metatable (if any)
if (!lua_getmetatable(info->luaState, -1)) {
lua_pushnil(info->luaState);
}
// >>>>> permTbl rootObj ...... udata metaTbl/nil
serialize(info);
lua_pop(info->luaState, 1);
/* perms reftbl ... udata */
}
} // End of namespace Lua
|