summaryrefslogtreecommitdiff
path: root/js/src/vm/ArrayBufferObject.cpp
blob: 79db90ac743ea01b15c9769f95d869469f033504 (plain)
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
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "vm/ArrayBufferObject-inl.h"
#include "vm/ArrayBufferObject.h"

#include "mozilla/Alignment.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/FloatingPoint.h"
#include "mozilla/Maybe.h"
#include "mozilla/PodOperations.h"
#include "mozilla/TaggedAnonymousMemory.h"

#include <string.h>
#ifndef XP_WIN
# include <sys/mman.h>
#endif

#ifdef MOZ_VALGRIND
# include <valgrind/memcheck.h>
#endif

#include "jsapi.h"
#include "jsarray.h"
#include "jscntxt.h"
#include "jscpucfg.h"
#include "jsfriendapi.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jstypes.h"
#include "jsutil.h"
#ifdef XP_WIN
# include "jswin.h"
#endif
#include "jswrapper.h"

#include "gc/Barrier.h"
#include "gc/Marking.h"
#include "gc/Memory.h"
#include "js/Conversions.h"
#include "js/MemoryMetrics.h"
#include "vm/GlobalObject.h"
#include "vm/Interpreter.h"
#include "vm/SelfHosting.h"
#include "vm/SharedArrayObject.h"
#include "vm/WrapperObject.h"
#include "wasm/WasmSignalHandlers.h"
#include "wasm/WasmTypes.h"

#include "jsatominlines.h"

#include "vm/NativeObject-inl.h"
#include "vm/Shape-inl.h"

using JS::ToInt32;

using mozilla::DebugOnly;
using mozilla::CheckedInt;
using mozilla::Some;
using mozilla::Maybe;
using mozilla::Nothing;

using namespace js;
using namespace js::gc;

/*
 * Convert |v| to an array index for an array of length |length| per
 * the Typed Array Specification section 7.0, |subarray|. If successful,
 * the output value is in the range [0, length].
 */
bool
js::ToClampedIndex(JSContext* cx, HandleValue v, uint32_t length, uint32_t* out)
{
    int32_t result;
    if (!ToInt32(cx, v, &result))
        return false;
    if (result < 0) {
        result += length;
        if (result < 0)
            result = 0;
    } else if (uint32_t(result) > length) {
        result = length;
    }
    *out = uint32_t(result);
    return true;
}

static bool
arraybuffer_static_slice(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1) {
        ReportMissingArg(cx, args.calleev(), 1);
        return false;
    }

    if (!GlobalObject::warnOnceAboutArrayBufferSlice(cx, cx->global()))
        return false;

    FixedInvokeArgs<2> args2(cx);
    args2[0].set(args.get(1));
    args2[1].set(args.get(2));
    return CallSelfHostedFunction(cx, "ArrayBufferSlice", args[0], args2, args.rval());
}

/*
 * ArrayBufferObject
 *
 * This class holds the underlying raw buffer that the TypedArrayObject classes
 * access.  It can be created explicitly and passed to a TypedArrayObject, or
 * can be created implicitly by constructing a TypedArrayObject with a size.
 */

/*
 * ArrayBufferObject (base)
 */

static const ClassSpec ArrayBufferObjectProtoClassSpec = {
    DELEGATED_CLASSSPEC(ArrayBufferObject::class_.spec),
    nullptr,
    nullptr,
    nullptr,
    nullptr,
    nullptr,
    nullptr,
    ClassSpec::IsDelegated
};

static const Class ArrayBufferObjectProtoClass = {
    "ArrayBufferPrototype",
    JSCLASS_HAS_CACHED_PROTO(JSProto_ArrayBuffer),
    JS_NULL_CLASS_OPS,
    &ArrayBufferObjectProtoClassSpec
};

static JSObject*
CreateArrayBufferPrototype(JSContext* cx, JSProtoKey key)
{
    return GlobalObject::createBlankPrototype(cx, cx->global(), &ArrayBufferObjectProtoClass);
}

static const ClassOps ArrayBufferObjectClassOps = {
    nullptr,        /* addProperty */
    nullptr,        /* delProperty */
    nullptr,        /* getProperty */
    nullptr,        /* setProperty */
    nullptr,        /* enumerate */
    nullptr,        /* resolve */
    nullptr,        /* mayResolve */
    ArrayBufferObject::finalize,
    nullptr,        /* call        */
    nullptr,        /* hasInstance */
    nullptr,        /* construct   */
    ArrayBufferObject::trace,
};

static const JSFunctionSpec static_functions[] = {
    JS_FN("isView", ArrayBufferObject::fun_isView, 1, 0),
    JS_FN("slice", arraybuffer_static_slice, 3, 0),
    JS_FS_END
};

static const JSPropertySpec static_properties[] = {
    JS_SELF_HOSTED_SYM_GET(species, "ArrayBufferSpecies", 0),
    JS_PS_END
};


static const JSFunctionSpec prototype_functions[] = {
    JS_SELF_HOSTED_FN("slice", "ArrayBufferSlice", 2, 0),
    JS_FS_END
};

static const JSPropertySpec prototype_properties[] = {
    JS_PSG("byteLength", ArrayBufferObject::byteLengthGetter, 0),
    JS_STRING_SYM_PS(toStringTag, "ArrayBuffer", JSPROP_READONLY),
    JS_PS_END
};

static const ClassSpec ArrayBufferObjectClassSpec = {
    GenericCreateConstructor<ArrayBufferObject::class_constructor, 1, gc::AllocKind::FUNCTION>,
    CreateArrayBufferPrototype,
    static_functions,
    static_properties,
    prototype_functions,
    prototype_properties
};

static const ClassExtension ArrayBufferObjectClassExtension = {
    nullptr,    /* weakmapKeyDelegateOp */
    ArrayBufferObject::objectMoved
};

const Class ArrayBufferObject::class_ = {
    "ArrayBuffer",
    JSCLASS_DELAY_METADATA_BUILDER |
    JSCLASS_HAS_RESERVED_SLOTS(RESERVED_SLOTS) |
    JSCLASS_HAS_CACHED_PROTO(JSProto_ArrayBuffer) |
    JSCLASS_BACKGROUND_FINALIZE,
    &ArrayBufferObjectClassOps,
    &ArrayBufferObjectClassSpec,
    &ArrayBufferObjectClassExtension
};

bool
js::IsArrayBuffer(HandleValue v)
{
    return v.isObject() && v.toObject().is<ArrayBufferObject>();
}

bool
js::IsArrayBuffer(HandleObject obj)
{
    return obj->is<ArrayBufferObject>();
}

bool
js::IsArrayBuffer(JSObject* obj)
{
    return obj->is<ArrayBufferObject>();
}

ArrayBufferObject&
js::AsArrayBuffer(HandleObject obj)
{
    MOZ_ASSERT(IsArrayBuffer(obj));
    return obj->as<ArrayBufferObject>();
}

ArrayBufferObject&
js::AsArrayBuffer(JSObject* obj)
{
    MOZ_ASSERT(IsArrayBuffer(obj));
    return obj->as<ArrayBufferObject>();
}

MOZ_ALWAYS_INLINE bool
ArrayBufferObject::byteLengthGetterImpl(JSContext* cx, const CallArgs& args)
{
    MOZ_ASSERT(IsArrayBuffer(args.thisv()));
    args.rval().setInt32(args.thisv().toObject().as<ArrayBufferObject>().byteLength());
    return true;
}

bool
ArrayBufferObject::byteLengthGetter(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return CallNonGenericMethod<IsArrayBuffer, byteLengthGetterImpl>(cx, args);
}

/*
 * ArrayBuffer.isView(obj); ES6 (Dec 2013 draft) 24.1.3.1
 */
bool
ArrayBufferObject::fun_isView(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    args.rval().setBoolean(args.get(0).isObject() &&
                           JS_IsArrayBufferViewObject(&args.get(0).toObject()));
    return true;
}


// ES2017 draft 24.1.2.1
bool
ArrayBufferObject::class_constructor(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    // Step 1.
    if (!ThrowIfNotConstructing(cx, args, "ArrayBuffer"))
        return false;

    // Step 2.
    uint64_t byteLength;
    if (!ToIndex(cx, args.get(0), &byteLength))
        return false;

    // Non-standard: Refuse to allocate buffers larger than ~2 GiB.
    if (byteLength > INT32_MAX) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_ARRAY_LENGTH);
        return false;
    }

    RootedObject proto(cx);
    RootedObject newTarget(cx, &args.newTarget().toObject());
    if (!GetPrototypeFromConstructor(cx, newTarget, &proto))
        return false;

    JSObject* bufobj = create(cx, uint32_t(byteLength), proto);
    if (!bufobj)
        return false;
    args.rval().setObject(*bufobj);
    return true;
}

static ArrayBufferObject::BufferContents
AllocateArrayBufferContents(JSContext* cx, uint32_t nbytes)
{
    uint8_t* p = cx->runtime()->pod_callocCanGC<uint8_t>(nbytes);
    if (!p)
        ReportOutOfMemory(cx);

    return ArrayBufferObject::BufferContents::create<ArrayBufferObject::PLAIN>(p);
}

static void
NoteViewBufferWasDetached(ArrayBufferViewObject* view,
                          ArrayBufferObject::BufferContents newContents,
                          JSContext* cx)
{
    view->notifyBufferDetached(cx, newContents.data());

    // Notify compiled jit code that the base pointer has moved.
    MarkObjectStateChange(cx, view);
}

/* static */ void
ArrayBufferObject::detach(JSContext* cx, Handle<ArrayBufferObject*> buffer,
                          BufferContents newContents)
{
    assertSameCompartment(cx, buffer);
    MOZ_ASSERT(!buffer->isPreparedForAsmJS());

    // When detaching buffers where we don't know all views, the new data must
    // match the old data. All missing views are typed objects, which do not
    // expect their data to ever change.
    MOZ_ASSERT_IF(buffer->forInlineTypedObject(),
                  newContents.data() == buffer->dataPointer());

    // When detaching a buffer with typed object views, any jitcode accessing
    // such views must be deoptimized so that detachment checks are performed.
    // This is done by setting a compartment-wide flag indicating that buffers
    // with typed object views have been detached.
    if (buffer->hasTypedObjectViews()) {
        // Make sure the global object's group has been instantiated, so the
        // flag change will be observed.
        AutoEnterOOMUnsafeRegion oomUnsafe;
        if (!JSObject::getGroup(cx, cx->global()))
            oomUnsafe.crash("ArrayBufferObject::detach");
        MarkObjectGroupFlags(cx, cx->global(), OBJECT_FLAG_TYPED_OBJECT_HAS_DETACHED_BUFFER);
        cx->compartment()->detachedTypedObjects = 1;
    }

    // Update all views of the buffer to account for the buffer having been
    // detached, and clear the buffer's data and list of views.

    auto& innerViews = cx->compartment()->innerViews.get();
    if (InnerViewTable::ViewVector* views = innerViews.maybeViewsUnbarriered(buffer)) {
        for (size_t i = 0; i < views->length(); i++)
            NoteViewBufferWasDetached((*views)[i], newContents, cx);
        innerViews.removeViews(buffer);
    }
    if (buffer->firstView()) {
        if (buffer->forInlineTypedObject()) {
            // The buffer points to inline data in its first view, so to keep
            // this pointer alive we don't clear out the first view.
            MOZ_ASSERT(buffer->firstView()->is<InlineTransparentTypedObject>());
        } else {
            NoteViewBufferWasDetached(buffer->firstView(), newContents, cx);
            buffer->setFirstView(nullptr);
        }
    }

    if (newContents.data() != buffer->dataPointer())
        buffer->setNewData(cx->runtime()->defaultFreeOp(), newContents, OwnsData);

    buffer->setByteLength(0);
    buffer->setIsDetached();
}

void
ArrayBufferObject::setNewData(FreeOp* fop, BufferContents newContents, OwnsState ownsState)
{
    if (ownsData()) {
        MOZ_ASSERT(newContents.data() != dataPointer());
        releaseData(fop);
    }

    setDataPointer(newContents, ownsState);
}

// This is called *only* from changeContents(), below.
// By construction, every view parameter will be mapping unshared memory (an ArrayBuffer).
// Hence no reason to worry about shared memory here.

void
ArrayBufferObject::changeViewContents(JSContext* cx, ArrayBufferViewObject* view,
                                      uint8_t* oldDataPointer, BufferContents newContents)
{
    MOZ_ASSERT(!view->isSharedMemory());

    // Watch out for NULL data pointers in views. This means that the view
    // is not fully initialized (in which case it'll be initialized later
    // with the correct pointer).
    JS::AutoCheckCannotGC nogc(cx);
    uint8_t* viewDataPointer = view->dataPointerUnshared(nogc);
    if (viewDataPointer) {
        MOZ_ASSERT(newContents);
        ptrdiff_t offset = viewDataPointer - oldDataPointer;
        viewDataPointer = static_cast<uint8_t*>(newContents.data()) + offset;
        view->setDataPointerUnshared(viewDataPointer);
    }

    // Notify compiled jit code that the base pointer has moved.
    MarkObjectStateChange(cx, view);
}

// BufferContents is specific to ArrayBuffer, hence it will not represent shared memory.

void
ArrayBufferObject::changeContents(JSContext* cx, BufferContents newContents,
                                  OwnsState ownsState)
{
    MOZ_RELEASE_ASSERT(!isWasm());
    MOZ_ASSERT(!forInlineTypedObject());

    // Change buffer contents.
    uint8_t* oldDataPointer = dataPointer();
    setNewData(cx->runtime()->defaultFreeOp(), newContents, ownsState);

    // Update all views.
    auto& innerViews = cx->compartment()->innerViews.get();
    if (InnerViewTable::ViewVector* views = innerViews.maybeViewsUnbarriered(this)) {
        for (size_t i = 0; i < views->length(); i++)
            changeViewContents(cx, (*views)[i], oldDataPointer, newContents);
    }
    if (firstView())
        changeViewContents(cx, firstView(), oldDataPointer, newContents);
}

/*
 * Wasm Raw Buf Linear Memory Structure
 *
 * The linear heap in Wasm is an mmaped array buffer. Several
 * constants manage its lifetime:
 *
 *  - length - the wasm-visible current length of the buffer. Acesses in the
 *    range [0, length] succeed. May only increase
 *
 *  - boundsCheckLimit - when !WASM_HUGE_MEMORY, the size against which we
 *    perform bounds checks. It is always a constant offset smaller than
 *    mappedSize. Currently that constant offset is 0.
 *
 *  - max - the optional declared limit on how much length can grow.
 *
 *  - mappedSize - the actual mmaped size. Access in the range
 *    [0, mappedSize] will either succeed, or be handled by the wasm signal
 *    handlers.
 *
 * The below diagram shows the layout of the wams heap. The wasm-visible
 * portion of the heap starts at 0. There is one extra page prior to the
 * start of the wasm heap which contains the WasmArrayRawBuffer struct at
 * its end. (i.e. right before the start of the WASM heap).
 *
 *  WasmArrayRawBuffer
 *      \    ArrayBufferObject::dataPointer()
 *       \  /
 *        \ |
 *  ______|_|____________________________________________________________
 * |______|_|______________|___________________|____________|____________|
 *          0          length              maxSize  boundsCheckLimit  mappedSize
 *
 * \_______________________/
 *          COMMITED
 *                          \____________________________________________/
 *                                           SLOP
 * \_____________________________________________________________________/
 *                         MAPPED
 *
 * Invariants:
 *  - length only increases
 *  - 0 <= length <= maxSize (if present) <= boundsCheckLimit <= mappedSize
 *  - on ARM boundsCheckLimit must be a valid ARM immediate.
 *  - if maxSize is not specified, boundsCheckLimit/mappedSize may grow. They are
 *    otherwise constant.
 *
 * NOTE: For asm.js on non-x64 we guarantee that
 *
 * length == maxSize == boundsCheckLimit == mappedSize
 *
 * That is, signal handlers will not be invoked, since they cannot emulate
 * asm.js accesses on non-x64 architectures.
 *
 * The region between length and mappedSize is the SLOP - an area where we use
 * signal handlers to catch things that slip by bounds checks. Logically it has
 * two parts:
 *
 *  - from length to boundsCheckLimit - this part of the SLOP serves to catch
 *  accesses to memory we have reserved but not yet grown into. This allows us
 *  to grow memory up to max (when present) without having to patch/update the
 *  bounds checks.
 *
 *  - from boundsCheckLimit to mappedSize - (Note: In current patch 0) - this
 *  part of the SLOP allows us to bounds check against base pointers and fold
 *  some constant offsets inside loads. This enables better Bounds
 *  Check Elimination.
 *
 */

class js::WasmArrayRawBuffer
{
    Maybe<uint32_t> maxSize_;
    size_t mappedSize_;

  protected:
    WasmArrayRawBuffer(uint8_t* buffer, uint32_t length, Maybe<uint32_t> maxSize, size_t mappedSize)
      : maxSize_(maxSize), mappedSize_(mappedSize)
    {
        MOZ_ASSERT(buffer == dataPointer());
    }

  public:
    static WasmArrayRawBuffer* Allocate(uint32_t numBytes, Maybe<uint32_t> maxSize);
    static void Release(void* mem);

    uint8_t* dataPointer() {
        uint8_t* ptr = reinterpret_cast<uint8_t*>(this);
        return ptr + sizeof(WasmArrayRawBuffer);
    }

    uint8_t* basePointer() {
        return dataPointer() - gc::SystemPageSize();
    }

    size_t mappedSize() const {
        return mappedSize_;
    }

    Maybe<uint32_t> maxSize() const {
        return maxSize_;
    }

    size_t allocatedBytes() const {
        return mappedSize_ + gc::SystemPageSize();
    }

#ifndef WASM_HUGE_MEMORY
    uint32_t boundsCheckLimit() const {
        MOZ_ASSERT(mappedSize_ <= UINT32_MAX);
        MOZ_ASSERT(mappedSize_ >= wasm::GuardSize);
        MOZ_ASSERT(wasm::IsValidBoundsCheckImmediate(mappedSize_ - wasm::GuardSize));
        return mappedSize_ - wasm::GuardSize;
    }
#endif

    [[nodiscard]] bool growToSizeInPlace(uint32_t oldSize, uint32_t newSize) {
        MOZ_ASSERT(newSize >= oldSize);
        MOZ_ASSERT_IF(maxSize(), newSize <= maxSize().value());
        MOZ_ASSERT(newSize <= mappedSize());

        uint32_t delta = newSize - oldSize;
        MOZ_ASSERT(delta % wasm::PageSize == 0);

        uint8_t* dataEnd = dataPointer() + oldSize;
        MOZ_ASSERT(uintptr_t(dataEnd) % gc::SystemPageSize() == 0);
# ifdef XP_WIN
        if (delta && !VirtualAlloc(dataEnd, delta, MEM_COMMIT, PAGE_READWRITE))
            return false;
# else  // XP_WIN
        if (delta && mprotect(dataEnd, delta, PROT_READ | PROT_WRITE))
            return false;
# endif  // !XP_WIN

#  if defined(MOZ_VALGRIND) && defined(VALGRIND_DISABLE_ADDR_ERROR_REPORTING_IN_RANGE)
        VALGRIND_ENABLE_ADDR_ERROR_REPORTING_IN_RANGE((unsigned char*)dataEnd, delta);
#  endif

        MemProfiler::SampleNative(dataEnd, delta);
        return true;
    }

#ifndef WASM_HUGE_MEMORY
    bool extendMappedSize(uint32_t maxSize) {
        size_t newMappedSize = wasm::ComputeMappedSize(maxSize);
        MOZ_ASSERT(mappedSize_ <= newMappedSize);
        if (mappedSize_ == newMappedSize)
            return true;

# ifdef XP_WIN
        uint8_t* mappedEnd = dataPointer() + mappedSize_;
        uint32_t delta = newMappedSize - mappedSize_;
        if (!VirtualAlloc(mappedEnd, delta, MEM_RESERVE, PAGE_NOACCESS))
            return false;
# elif defined(XP_LINUX)
        // Note this will not move memory (no MREMAP_MAYMOVE specified)
        if (MAP_FAILED == mremap(dataPointer(), mappedSize_, newMappedSize, 0))
            return false;
# else
        // No mechanism for remapping on MacOS and other Unices. Luckily
        // shouldn't need it here as most of these are 64-bit.
        return false;
# endif

        mappedSize_ = newMappedSize;
        return true;
    }

    // Try and grow the mapped region of memory. Does not changes current size.
    // Does not move memory if no space to grow.
    void tryGrowMaxSizeInPlace(uint32_t deltaMaxSize) {
        CheckedInt<uint32_t> newMaxSize = maxSize_.value();
        newMaxSize += deltaMaxSize;
        MOZ_ASSERT(newMaxSize.isValid());
        MOZ_ASSERT(newMaxSize.value() % wasm::PageSize == 0);

        if (!extendMappedSize(newMaxSize.value()))
            return;

        maxSize_ = Some(newMaxSize.value());
    }
#endif // WASM_HUGE_MEMORY
};

/* static */ WasmArrayRawBuffer*
WasmArrayRawBuffer::Allocate(uint32_t numBytes, Maybe<uint32_t> maxSize)
{
    size_t mappedSize;
#ifdef WASM_HUGE_MEMORY
    mappedSize = wasm::HugeMappedSize;
#else
    mappedSize = wasm::ComputeMappedSize(maxSize.valueOr(numBytes));
#endif

    MOZ_RELEASE_ASSERT(mappedSize <= SIZE_MAX - gc::SystemPageSize());
    MOZ_RELEASE_ASSERT(numBytes <= maxSize.valueOr(UINT32_MAX));
    MOZ_ASSERT(numBytes % gc::SystemPageSize() == 0);
    MOZ_ASSERT(mappedSize % gc::SystemPageSize() == 0);

    uint64_t mappedSizeWithHeader = mappedSize + gc::SystemPageSize();
    uint64_t numBytesWithHeader = numBytes + gc::SystemPageSize();

# ifdef XP_WIN
    void* data = VirtualAlloc(nullptr, (size_t) mappedSizeWithHeader, MEM_RESERVE, PAGE_NOACCESS);
    if (!data)
        return nullptr;

    if (!VirtualAlloc(data, numBytesWithHeader, MEM_COMMIT, PAGE_READWRITE)) {
        VirtualFree(data, 0, MEM_RELEASE);
        return nullptr;
    }
# else  // XP_WIN
    void* data = MozTaggedAnonymousMmap(nullptr, (size_t) mappedSizeWithHeader, PROT_NONE,
                                        MAP_PRIVATE | MAP_ANON, -1, 0, "wasm-reserved");
    if (data == MAP_FAILED)
        return nullptr;

    // Note we will waste a page on zero-sized memories here
    if (mprotect(data, numBytesWithHeader, PROT_READ | PROT_WRITE)) {
        munmap(data, mappedSizeWithHeader);
        return nullptr;
    }
# endif  // !XP_WIN
    MemProfiler::SampleNative(data, numBytesWithHeader);

#  if defined(MOZ_VALGRIND) && defined(VALGRIND_DISABLE_ADDR_ERROR_REPORTING_IN_RANGE)
    VALGRIND_DISABLE_ADDR_ERROR_REPORTING_IN_RANGE((unsigned char*)data + numBytesWithHeader,
                                                   mappedSizeWithHeader - numBytesWithHeader);
#  endif

    uint8_t* base = reinterpret_cast<uint8_t*>(data) + gc::SystemPageSize();
    uint8_t* header = base - sizeof(WasmArrayRawBuffer);

    auto rawBuf = new (header) WasmArrayRawBuffer(base, numBytes, maxSize, mappedSize);
    return rawBuf;
}

/* static */ void
WasmArrayRawBuffer::Release(void* mem)
{
    WasmArrayRawBuffer* header = (WasmArrayRawBuffer*)((uint8_t*)mem - sizeof(WasmArrayRawBuffer));
    uint8_t* base = header->basePointer();
    MOZ_RELEASE_ASSERT(header->mappedSize() <= SIZE_MAX - gc::SystemPageSize());
    size_t mappedSizeWithHeader = header->mappedSize() + gc::SystemPageSize();

    MemProfiler::RemoveNative(base);
# ifdef XP_WIN
    VirtualFree(base, 0, MEM_RELEASE);
# else  // XP_WIN
    munmap(base, mappedSizeWithHeader);
# endif  // !XP_WIN

#  if defined(MOZ_VALGRIND) && defined(VALGRIND_ENABLE_ADDR_ERROR_REPORTING_IN_RANGE)
    VALGRIND_ENABLE_ADDR_ERROR_REPORTING_IN_RANGE(base, mappedSizeWithHeader);
#  endif
}

WasmArrayRawBuffer*
ArrayBufferObject::BufferContents::wasmBuffer() const
{
    MOZ_RELEASE_ASSERT(kind_ == WASM);
    return (WasmArrayRawBuffer*)(data_ - sizeof(WasmArrayRawBuffer));
}

#define ROUND_UP(v, a) ((v) % (a) == 0 ? (v) : v + a - ((v) % (a)))

/* static */ ArrayBufferObject*
ArrayBufferObject::createForWasm(JSContext* cx, uint32_t initialSize, Maybe<uint32_t> maxSize)
{
    MOZ_ASSERT(initialSize % wasm::PageSize == 0);
    MOZ_RELEASE_ASSERT(wasm::HaveSignalHandlers());

    // Prevent applications specifying a large max (like UINT32_MAX) from
    // unintentially OOMing the browser on 32-bit: they just want "a lot of
    // memory". Maintain the invariant that initialSize <= maxSize.
    if (sizeof(void*) == 4 && maxSize) {
        static const uint32_t OneGiB = 1 << 30;
        uint32_t clamp = Max(OneGiB, initialSize);
        maxSize = Some(Min(clamp, maxSize.value()));
    }

    RootedArrayBufferObject buffer(cx, ArrayBufferObject::createEmpty(cx));
    if (!buffer)
        return nullptr;

    // Try to reserve the maximum requested memory
    WasmArrayRawBuffer* wasmBuf = WasmArrayRawBuffer::Allocate(initialSize, maxSize);
    if (!wasmBuf) {
#ifdef  WASM_HUGE_MEMORY
        ReportOutOfMemory(cx);
        return nullptr;
#else
        // If we fail, and have a maxSize, try to reserve the biggest chunk in
        // the range [initialSize, maxSize) using log backoff.
        if (!maxSize) {
            ReportOutOfMemory(cx);
            return nullptr;
        }

        uint32_t cur = maxSize.value() / 2;

        for (; cur > initialSize; cur /= 2) {
            wasmBuf = WasmArrayRawBuffer::Allocate(initialSize, Some(ROUND_UP(cur, wasm::PageSize)));
            if (wasmBuf)
                break;
        }

        if (!wasmBuf) {
            ReportOutOfMemory(cx);
            return nullptr;
        }

        // Try to grow our chunk as much as possible.
        for (size_t d = cur / 2; d >= wasm::PageSize; d /= 2)
            wasmBuf->tryGrowMaxSizeInPlace(ROUND_UP(d, wasm::PageSize));
#endif
    }

    auto contents = BufferContents::create<WASM>(wasmBuf->dataPointer());
    buffer->initialize(initialSize, contents, OwnsData);
    cx->zone()->updateMallocCounter(wasmBuf->mappedSize());
    return buffer;
}

// Note this function can return false with or without an exception pending. The
// asm.js caller checks cx->isExceptionPending before propagating failure.
// Returning false without throwing means that asm.js linking will fail which
// will recompile as non-asm.js.
/* static */ bool
ArrayBufferObject::prepareForAsmJS(JSContext* cx, Handle<ArrayBufferObject*> buffer, bool needGuard)
{
#ifdef WASM_HUGE_MEMORY
    MOZ_ASSERT(needGuard);
#endif
    MOZ_ASSERT(buffer->byteLength() % wasm::PageSize == 0);
    MOZ_RELEASE_ASSERT(wasm::HaveSignalHandlers());

    if (buffer->forInlineTypedObject())
        return false;

    if (needGuard) {
        if (buffer->isWasm() && buffer->isPreparedForAsmJS())
            return true;

        // Non-prepared-for-asm.js wasm buffers can be detached at any time.
        // This error can only be triggered for Atomics on !WASM_HUGE_MEMORY,
        // so this error is only visible in testing.
        if (buffer->isWasm() || buffer->isPreparedForAsmJS())
            return false;

        uint32_t length = buffer->byteLength();
        WasmArrayRawBuffer* wasmBuf = WasmArrayRawBuffer::Allocate(length, Some(length));
        if (!wasmBuf) {
            ReportOutOfMemory(cx);
            return false;
        }

        void* data = wasmBuf->dataPointer();
        memcpy(data, buffer->dataPointer(), length);

        // Swap the new elements into the ArrayBufferObject. Mark the
        // ArrayBufferObject so we don't do this again.
        buffer->changeContents(cx, BufferContents::create<WASM>(data), OwnsData);
        buffer->setIsPreparedForAsmJS();
        MOZ_ASSERT(data == buffer->dataPointer());
        cx->zone()->updateMallocCounter(wasmBuf->mappedSize());
        return true;
    }

    if (!buffer->isWasm() && buffer->isPreparedForAsmJS())
        return true;

    // Non-prepared-for-asm.js wasm buffers can be detached at any time.
    if (buffer->isWasm())
        return false;

    if (!buffer->ownsData()) {
        BufferContents contents = AllocateArrayBufferContents(cx, buffer->byteLength());
        if (!contents)
            return false;
        memcpy(contents.data(), buffer->dataPointer(), buffer->byteLength());
        buffer->changeContents(cx, contents, OwnsData);
    }

    buffer->setIsPreparedForAsmJS();
    return true;
}

ArrayBufferObject::BufferContents
ArrayBufferObject::createMappedContents(int fd, size_t offset, size_t length)
{
    void* data = AllocateMappedContent(fd, offset, length, ARRAY_BUFFER_ALIGNMENT);
    MemProfiler::SampleNative(data, length);
    return BufferContents::create<MAPPED>(data);
}

uint8_t*
ArrayBufferObject::inlineDataPointer() const
{
    return static_cast<uint8_t*>(fixedData(JSCLASS_RESERVED_SLOTS(&class_)));
}

uint8_t*
ArrayBufferObject::dataPointer() const
{
    return static_cast<uint8_t*>(getSlot(DATA_SLOT).toPrivate());
}

SharedMem<uint8_t*>
ArrayBufferObject::dataPointerShared() const
{
    return SharedMem<uint8_t*>::unshared(getSlot(DATA_SLOT).toPrivate());
}

void
ArrayBufferObject::releaseData(FreeOp* fop)
{
    MOZ_ASSERT(ownsData());

    switch (bufferKind()) {
      case PLAIN:
        fop->free_(dataPointer());
        break;
      case MAPPED:
        MemProfiler::RemoveNative(dataPointer());
        DeallocateMappedContent(dataPointer(), byteLength());
        break;
      case WASM:
        WasmArrayRawBuffer::Release(dataPointer());
        break;
      case KIND_MASK:
        MOZ_CRASH("bad bufferKind()");
    }
}

void
ArrayBufferObject::setDataPointer(BufferContents contents, OwnsState ownsData)
{
    setSlot(DATA_SLOT, PrivateValue(contents.data()));
    setOwnsData(ownsData);
    setFlags((flags() & ~KIND_MASK) | contents.kind());
}

uint32_t
ArrayBufferObject::byteLength() const
{
    return getSlot(BYTE_LENGTH_SLOT).toInt32();
}

void
ArrayBufferObject::setByteLength(uint32_t length)
{
    MOZ_ASSERT(length <= INT32_MAX);
    setSlot(BYTE_LENGTH_SLOT, Int32Value(length));
}

size_t
ArrayBufferObject::wasmMappedSize() const
{
    if (isWasm())
        return contents().wasmBuffer()->mappedSize();
    return byteLength();
}

size_t
js::WasmArrayBufferMappedSize(const ArrayBufferObjectMaybeShared* buf)
{
    if (buf->is<ArrayBufferObject>())
        return buf->as<ArrayBufferObject>().wasmMappedSize();
#ifdef WASM_HUGE_MEMORY
    return wasm::HugeMappedSize;
#else
    return buf->as<SharedArrayBufferObject>().byteLength();
#endif
}

Maybe<uint32_t>
ArrayBufferObject::wasmMaxSize() const
{
    if (isWasm())
        return contents().wasmBuffer()->maxSize();
    else
        return Some<uint32_t>(byteLength());
}

Maybe<uint32_t>
js::WasmArrayBufferMaxSize(const ArrayBufferObjectMaybeShared* buf)
{
    if (buf->is<ArrayBufferObject>())
        return buf->as<ArrayBufferObject>().wasmMaxSize();

    return Some(buf->as<SharedArrayBufferObject>().byteLength());
}

/* static */ bool
ArrayBufferObject::wasmGrowToSizeInPlace(uint32_t newSize,
                                         HandleArrayBufferObject oldBuf,
                                         MutableHandleArrayBufferObject newBuf,
                                         JSContext* cx)
{
    // On failure, do not throw and ensure that the original buffer is
    // unmodified and valid. After WasmArrayRawBuffer::growToSizeInPlace(), the
    // wasm-visible length of the buffer has been increased so it must be the
    // last fallible operation.

    // byteLength can be at most INT32_MAX.
    if (newSize > INT32_MAX)
        return false;

    newBuf.set(ArrayBufferObject::createEmpty(cx));
    if (!newBuf) {
        cx->clearPendingException();
        return false;
    }

    if (!oldBuf->contents().wasmBuffer()->growToSizeInPlace(oldBuf->byteLength(), newSize))
        return false;

    bool hasStealableContents = true;
    BufferContents contents = ArrayBufferObject::stealContents(cx, oldBuf, hasStealableContents);
    MOZ_ASSERT(contents);
    newBuf->initialize(newSize, contents, OwnsData);
    return true;
}

#ifndef WASM_HUGE_MEMORY
/* static */ bool
ArrayBufferObject::wasmMovingGrowToSize(uint32_t newSize,
                                        HandleArrayBufferObject oldBuf,
                                        MutableHandleArrayBufferObject newBuf,
                                        JSContext* cx)
{
    // On failure, do not throw and ensure that the original buffer is
    // unmodified and valid.

    // byteLength can be at most INT32_MAX.
    if (newSize > INT32_MAX)
        return false;

    if (newSize <= oldBuf->wasmBoundsCheckLimit() ||
        oldBuf->contents().wasmBuffer()->extendMappedSize(newSize))
    {
        return wasmGrowToSizeInPlace(newSize, oldBuf, newBuf, cx);
    }

    newBuf.set(ArrayBufferObject::createEmpty(cx));
    if (!newBuf) {
        cx->clearPendingException();
        return false;
    }

    WasmArrayRawBuffer* newRawBuf = WasmArrayRawBuffer::Allocate(newSize, Nothing());
    if (!newRawBuf)
        return false;
    BufferContents contents = BufferContents::create<WASM>(newRawBuf->dataPointer());
    newBuf->initialize(newSize, contents, OwnsData);

    memcpy(newBuf->dataPointer(), oldBuf->dataPointer(), oldBuf->byteLength());
    ArrayBufferObject::detach(cx, oldBuf, BufferContents::createPlain(nullptr));
    return true;
}

uint32_t
ArrayBufferObject::wasmBoundsCheckLimit() const
{
    if (isWasm())
        return contents().wasmBuffer()->boundsCheckLimit();
    else
        return byteLength();
}

uint32_t
ArrayBufferObjectMaybeShared::wasmBoundsCheckLimit() const
{
    if (is<ArrayBufferObject>())
        return as<ArrayBufferObject>().wasmBoundsCheckLimit();

    return as<SharedArrayBufferObject>().byteLength();
}
#endif

uint32_t
ArrayBufferObject::flags() const
{
    return uint32_t(getSlot(FLAGS_SLOT).toInt32());
}

void
ArrayBufferObject::setFlags(uint32_t flags)
{
    setSlot(FLAGS_SLOT, Int32Value(flags));
}

ArrayBufferObject*
ArrayBufferObject::create(JSContext* cx, uint32_t nbytes, BufferContents contents,
                          OwnsState ownsState /* = OwnsData */,
                          HandleObject proto /* = nullptr */,
                          NewObjectKind newKind /* = GenericObject */)
{
    MOZ_ASSERT_IF(contents.kind() == MAPPED, contents);

    // 24.1.1.1, step 3 (Inlined 6.2.6.1 CreateByteDataBlock, step 2).
    // Refuse to allocate too large buffers, currently limited to ~2 GiB.
    if (nbytes > INT32_MAX) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_ARRAY_LENGTH);
        return nullptr;
    }

    // If we need to allocate data, try to use a larger object size class so
    // that the array buffer's data can be allocated inline with the object.
    // The extra space will be left unused by the object's fixed slots and
    // available for the buffer's data, see NewObject().
    size_t reservedSlots = JSCLASS_RESERVED_SLOTS(&class_);

    size_t nslots = reservedSlots;
    bool allocated = false;
    if (contents) {
        if (ownsState == OwnsData) {
            // The ABO is taking ownership, so account the bytes against the zone.
            size_t nAllocated = nbytes;
            if (contents.kind() == MAPPED)
                nAllocated = JS_ROUNDUP(nbytes, js::gc::SystemPageSize());
            else if (contents.kind() == WASM)
                nAllocated = contents.wasmBuffer()->allocatedBytes();
            cx->zone()->updateMallocCounter(nAllocated);
        }
    } else {
        MOZ_ASSERT(ownsState == OwnsData);
        size_t usableSlots = NativeObject::MAX_FIXED_SLOTS - reservedSlots;
        if (nbytes <= usableSlots * sizeof(Value)) {
            int newSlots = (nbytes - 1) / sizeof(Value) + 1;
            MOZ_ASSERT(int(nbytes) <= newSlots * int(sizeof(Value)));
            nslots = reservedSlots + newSlots;
            contents = BufferContents::createPlain(nullptr);
        } else {
            contents = AllocateArrayBufferContents(cx, nbytes);
            if (!contents)
                return nullptr;
            allocated = true;
        }
    }

    MOZ_ASSERT(!(class_.flags & JSCLASS_HAS_PRIVATE));
    gc::AllocKind allocKind = GetGCObjectKind(nslots);

    AutoSetNewObjectMetadata metadata(cx);
    Rooted<ArrayBufferObject*> obj(cx,
        NewObjectWithClassProto<ArrayBufferObject>(cx, proto, allocKind, newKind));
    if (!obj) {
        if (allocated)
            js_free(contents.data());
        return nullptr;
    }

    MOZ_ASSERT(obj->getClass() == &class_);
    MOZ_ASSERT(!gc::IsInsideNursery(obj));

    if (!contents) {
        void* data = obj->inlineDataPointer();
        memset(data, 0, nbytes);
        obj->initialize(nbytes, BufferContents::createPlain(data), DoesntOwnData);
    } else {
        obj->initialize(nbytes, contents, ownsState);
    }

    return obj;
}

ArrayBufferObject*
ArrayBufferObject::create(JSContext* cx, uint32_t nbytes,
                          HandleObject proto /* = nullptr */,
                          NewObjectKind newKind /* = GenericObject */)
{
    return create(cx, nbytes, BufferContents::createPlain(nullptr),
                  OwnsState::OwnsData, proto);
}

ArrayBufferObject*
ArrayBufferObject::createEmpty(JSContext* cx)
{
    AutoSetNewObjectMetadata metadata(cx);
    ArrayBufferObject* obj = NewObjectWithClassProto<ArrayBufferObject>(cx, nullptr);
    if (!obj)
        return nullptr;

    obj->initEmpty();
    return obj;
}

bool
ArrayBufferObject::createDataViewForThisImpl(JSContext* cx, const CallArgs& args)
{
    MOZ_ASSERT(IsArrayBuffer(args.thisv()));

    /*
     * This method is only called for |DataView(alienBuf, ...)| which calls
     * this as |createDataViewForThis.call(alienBuf, byteOffset, byteLength,
     *                                     DataView.prototype)|,
     * ergo there must be exactly 3 arguments.
     */
    MOZ_ASSERT(args.length() == 3);

    uint32_t byteOffset = args[0].toPrivateUint32();
    uint32_t byteLength = args[1].toPrivateUint32();
    Rooted<ArrayBufferObject*> buffer(cx, &args.thisv().toObject().as<ArrayBufferObject>());

    /*
     * Pop off the passed-along prototype and delegate to normal DataViewObject
     * construction.
     */
    JSObject* obj = DataViewObject::create(cx, byteOffset, byteLength, buffer, &args[2].toObject());
    if (!obj)
        return false;
    args.rval().setObject(*obj);
    return true;
}

bool
ArrayBufferObject::createDataViewForThis(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return CallNonGenericMethod<IsArrayBuffer, createDataViewForThisImpl>(cx, args);
}

/* static */ ArrayBufferObject::BufferContents
ArrayBufferObject::externalizeContents(JSContext* cx, Handle<ArrayBufferObject*> buffer,
                                       bool hasStealableContents)
{
    MOZ_ASSERT(buffer->isPlain(), "Only support doing this on plain ABOs");
    MOZ_ASSERT(!buffer->isDetached(), "must have contents to externalize");
    MOZ_ASSERT_IF(hasStealableContents, buffer->hasStealableContents());

    BufferContents contents(buffer->dataPointer(), buffer->bufferKind());

    if (hasStealableContents) {
        buffer->setOwnsData(DoesntOwnData);
        return contents;
    }

    // Create a new chunk of memory to return since we cannot steal the
    // existing contents away from the buffer.
    BufferContents newContents = AllocateArrayBufferContents(cx, buffer->byteLength());
    if (!newContents)
        return BufferContents::createPlain(nullptr);
    memcpy(newContents.data(), contents.data(), buffer->byteLength());
    buffer->changeContents(cx, newContents, DoesntOwnData);

    return newContents;
}

/* static */ ArrayBufferObject::BufferContents
ArrayBufferObject::stealContents(JSContext* cx, Handle<ArrayBufferObject*> buffer,
                                 bool hasStealableContents)
{
    // While wasm buffers cannot generally be transferred by content, the
    // stealContents() is used internally by the impl of memory growth.
    MOZ_ASSERT_IF(hasStealableContents, buffer->hasStealableContents() ||
                                        (buffer->isWasm() && !buffer->isPreparedForAsmJS()));
    assertSameCompartment(cx, buffer);

    BufferContents oldContents(buffer->dataPointer(), buffer->bufferKind());

    if (hasStealableContents) {
        // Return the old contents and reset the detached buffer's data
        // pointer. This pointer should never be accessed.
        auto newContents = BufferContents::createPlain(nullptr);
        buffer->setOwnsData(DoesntOwnData); // Do not free the stolen data.
        ArrayBufferObject::detach(cx, buffer, newContents);
        buffer->setOwnsData(DoesntOwnData); // Do not free the nullptr.
        return oldContents;
    }

    // Create a new chunk of memory to return since we cannot steal the
    // existing contents away from the buffer.
    BufferContents contentsCopy = AllocateArrayBufferContents(cx, buffer->byteLength());
    if (!contentsCopy)
        return BufferContents::createPlain(nullptr);

    if (buffer->byteLength() > 0)
        memcpy(contentsCopy.data(), oldContents.data(), buffer->byteLength());
    ArrayBufferObject::detach(cx, buffer, oldContents);
    return contentsCopy;
}

/* static */ void
ArrayBufferObject::addSizeOfExcludingThis(JSObject* obj, mozilla::MallocSizeOf mallocSizeOf,
                                          JS::ClassInfo* info)
{
    ArrayBufferObject& buffer = AsArrayBuffer(obj);

    if (!buffer.ownsData())
        return;

    switch (buffer.bufferKind()) {
      case PLAIN:
        if (buffer.isPreparedForAsmJS())
            info->objectsMallocHeapElementsAsmJS += mallocSizeOf(buffer.dataPointer());
        else
            info->objectsMallocHeapElementsNormal += mallocSizeOf(buffer.dataPointer());
        break;
      case MAPPED:
        info->objectsNonHeapElementsNormal += buffer.byteLength();
        break;
      case WASM:
        info->objectsNonHeapElementsWasm += buffer.byteLength();
        MOZ_ASSERT(buffer.wasmMappedSize() >= buffer.byteLength());
        info->wasmGuardPages += buffer.wasmMappedSize() - buffer.byteLength();
        break;
      case KIND_MASK:
        MOZ_CRASH("bad bufferKind()");
    }
}

/* static */ void
ArrayBufferObject::finalize(FreeOp* fop, JSObject* obj)
{
    ArrayBufferObject& buffer = obj->as<ArrayBufferObject>();

    if (buffer.ownsData())
        buffer.releaseData(fop);
}

/* static */ void
ArrayBufferObject::copyData(Handle<ArrayBufferObject*> toBuffer, uint32_t toIndex,
                            Handle<ArrayBufferObject*> fromBuffer, uint32_t fromIndex,
                            uint32_t count)
{
    MOZ_ASSERT(toBuffer->byteLength() >= count);
    MOZ_ASSERT(toBuffer->byteLength() >= toIndex + count);
    MOZ_ASSERT(fromBuffer->byteLength() >= fromIndex);
    MOZ_ASSERT(fromBuffer->byteLength() >= fromIndex + count);

    memcpy(toBuffer->dataPointer() + toIndex, fromBuffer->dataPointer() + fromIndex, count);
}

/* static */ void
ArrayBufferObject::trace(JSTracer* trc, JSObject* obj)
{
    // If this buffer is associated with an inline typed object,
    // fix up the data pointer if the typed object was moved.
    ArrayBufferObject& buf = obj->as<ArrayBufferObject>();

    if (!buf.forInlineTypedObject())
        return;

    JSObject* view = MaybeForwarded(buf.firstView());
    MOZ_ASSERT(view && view->is<InlineTransparentTypedObject>());

    TraceManuallyBarrieredEdge(trc, &view, "array buffer inline typed object owner");
    buf.setSlot(DATA_SLOT, PrivateValue(view->as<InlineTransparentTypedObject>().inlineTypedMem()));
}

/* static */ void
ArrayBufferObject::objectMoved(JSObject* obj, const JSObject* old)
{
    ArrayBufferObject& dst = obj->as<ArrayBufferObject>();
    const ArrayBufferObject& src = old->as<ArrayBufferObject>();

    // Fix up possible inline data pointer.
    if (src.hasInlineData())
        dst.setSlot(DATA_SLOT, PrivateValue(dst.inlineDataPointer()));
}

ArrayBufferViewObject*
ArrayBufferObject::firstView()
{
    return getSlot(FIRST_VIEW_SLOT).isObject()
        ? static_cast<ArrayBufferViewObject*>(&getSlot(FIRST_VIEW_SLOT).toObject())
        : nullptr;
}

void
ArrayBufferObject::setFirstView(ArrayBufferViewObject* view)
{
    setSlot(FIRST_VIEW_SLOT, ObjectOrNullValue(view));
}

bool
ArrayBufferObject::addView(JSContext* cx, JSObject* viewArg)
{
    // Note: we don't pass in an ArrayBufferViewObject as the argument due to
    // tricky inheritance in the various view classes. View classes do not
    // inherit from ArrayBufferViewObject so won't be upcast automatically.
    MOZ_ASSERT(viewArg->is<ArrayBufferViewObject>() || viewArg->is<TypedObject>());
    ArrayBufferViewObject* view = static_cast<ArrayBufferViewObject*>(viewArg);

    if (!firstView()) {
        setFirstView(view);
        return true;
    }
    return cx->compartment()->innerViews.get().addView(cx, this, view);
}

/*
 * InnerViewTable
 */

static size_t VIEW_LIST_MAX_LENGTH = 500;

bool
InnerViewTable::addView(JSContext* cx, ArrayBufferObject* buffer, ArrayBufferViewObject* view)
{
    // ArrayBufferObject entries are only added when there are multiple views.
    MOZ_ASSERT(buffer->firstView());

    if (!map.initialized() && !map.init()) {
        ReportOutOfMemory(cx);
        return false;
    }

    Map::AddPtr p = map.lookupForAdd(buffer);

    MOZ_ASSERT(!gc::IsInsideNursery(buffer));
    bool addToNursery = nurseryKeysValid && gc::IsInsideNursery(view);

    if (p) {
        ViewVector& views = p->value();
        MOZ_ASSERT(!views.empty());

        if (addToNursery) {
            // Only add the entry to |nurseryKeys| if it isn't already there.
            if (views.length() >= VIEW_LIST_MAX_LENGTH) {
                // To avoid quadratic blowup, skip the loop below if we end up
                // adding enormous numbers of views for the same object.
                nurseryKeysValid = false;
            } else {
                for (size_t i = 0; i < views.length(); i++) {
                    if (gc::IsInsideNursery(views[i])) {
                        addToNursery = false;
                        break;
                    }
                }
            }
        }

        if (!views.append(view)) {
            ReportOutOfMemory(cx);
            return false;
        }
    } else {
        if (!map.add(p, buffer, ViewVector())) {
            ReportOutOfMemory(cx);
            return false;
        }
        // ViewVector has one inline element, so the first insertion is
        // guaranteed to succeed.
        MOZ_ALWAYS_TRUE(p->value().append(view));
    }

    if (addToNursery && !nurseryKeys.append(buffer))
        nurseryKeysValid = false;

    return true;
}

InnerViewTable::ViewVector*
InnerViewTable::maybeViewsUnbarriered(ArrayBufferObject* buffer)
{
    if (!map.initialized())
        return nullptr;

    Map::Ptr p = map.lookup(buffer);
    if (p)
        return &p->value();
    return nullptr;
}

void
InnerViewTable::removeViews(ArrayBufferObject* buffer)
{
    Map::Ptr p = map.lookup(buffer);
    MOZ_ASSERT(p);

    map.remove(p);
}

/* static */ bool
InnerViewTable::sweepEntry(JSObject** pkey, ViewVector& views)
{
    if (IsAboutToBeFinalizedUnbarriered(pkey))
        return true;

    MOZ_ASSERT(!views.empty());
    for (size_t i = 0; i < views.length(); i++) {
        if (IsAboutToBeFinalizedUnbarriered(&views[i])) {
            views[i--] = views.back();
            views.popBack();
        }
    }

    return views.empty();
}

void
InnerViewTable::sweep()
{
    MOZ_ASSERT(nurseryKeys.empty());
    map.sweep();
}

void
InnerViewTable::sweepAfterMinorGC()
{
    MOZ_ASSERT(needsSweepAfterMinorGC());

    if (nurseryKeysValid) {
        for (size_t i = 0; i < nurseryKeys.length(); i++) {
            JSObject* buffer = MaybeForwarded(nurseryKeys[i]);
            Map::Ptr p = map.lookup(buffer);
            if (!p)
                continue;

            if (sweepEntry(&p->mutableKey(), p->value()))
                map.remove(buffer);
        }
        nurseryKeys.clear();
    } else {
        // Do the required sweeping by looking at every map entry.
        nurseryKeys.clear();
        sweep();

        nurseryKeysValid = true;
    }
}

size_t
InnerViewTable::sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf)
{
    if (!map.initialized())
        return 0;

    size_t vectorSize = 0;
    for (Map::Enum e(map); !e.empty(); e.popFront())
        vectorSize += e.front().value().sizeOfExcludingThis(mallocSizeOf);

    return vectorSize
         + map.sizeOfExcludingThis(mallocSizeOf)
         + nurseryKeys.sizeOfExcludingThis(mallocSizeOf);
}

/*
 * ArrayBufferViewObject
 */

/*
 * This method is used to trace TypedArrayObjects and DataViewObjects. We need
 * a custom tracer to move the object's data pointer if its owner was moved and
 * stores its data inline.
 */
/* static */ void
ArrayBufferViewObject::trace(JSTracer* trc, JSObject* objArg)
{
    NativeObject* obj = &objArg->as<NativeObject>();
    HeapSlot& bufSlot = obj->getFixedSlotRef(TypedArrayObject::BUFFER_SLOT);
    TraceEdge(trc, &bufSlot, "typedarray.buffer");

    // Update obj's data pointer if it moved.
    if (bufSlot.isObject()) {
        if (IsArrayBuffer(&bufSlot.toObject())) {
            ArrayBufferObject& buf = AsArrayBuffer(MaybeForwarded(&bufSlot.toObject()));
            uint32_t offset = uint32_t(obj->getFixedSlot(TypedArrayObject::BYTEOFFSET_SLOT).toInt32());
            MOZ_ASSERT(offset <= INT32_MAX);

            if (buf.forInlineTypedObject()) {
                MOZ_ASSERT(buf.dataPointer() != nullptr);

                // The data is inline with an InlineTypedObject associated with the
                // buffer. Get a new address for the typed object if it moved.
                JSObject* view = buf.firstView();

                // Mark the object to move it into the tenured space.
                TraceManuallyBarrieredEdge(trc, &view, "typed array nursery owner");
                MOZ_ASSERT(view->is<InlineTypedObject>());
                MOZ_ASSERT(view != obj);

                void* srcData = obj->getPrivate();
                void* dstData = view->as<InlineTypedObject>().inlineTypedMemForGC() + offset;
                obj->setPrivateUnbarriered(dstData);

                // We can't use a direct forwarding pointer here, as there might
                // not be enough bytes available, and other views might have data
                // pointers whose forwarding pointers would overlap this one.
                trc->runtime()->gc.nursery.maybeSetForwardingPointer(trc, srcData, dstData,
                                                                     /* direct = */ false);
            } else {
                MOZ_ASSERT_IF(buf.dataPointer() == nullptr, offset == 0);

                // The data may or may not be inline with the buffer. The buffer
                // can only move during a compacting GC, in which case its
                // objectMoved hook has already updated the buffer's data pointer.
                obj->initPrivate(buf.dataPointer() + offset);
            }
        }
    }
}

template <>
bool
JSObject::is<js::ArrayBufferViewObject>() const
{
    return is<DataViewObject>() || is<TypedArrayObject>();
}

template <>
bool
JSObject::is<js::ArrayBufferObjectMaybeShared>() const
{
    return is<ArrayBufferObject>() || is<SharedArrayBufferObject>();
}

void
ArrayBufferViewObject::notifyBufferDetached(JSContext* cx, void* newData)
{
    if (is<DataViewObject>()) {
        as<DataViewObject>().notifyBufferDetached(newData);
    } else if (is<TypedArrayObject>()) {
        if (as<TypedArrayObject>().isSharedMemory())
            return;
        as<TypedArrayObject>().notifyBufferDetached(cx, newData);
    } else {
        as<OutlineTypedObject>().notifyBufferDetached(newData);
    }
}

uint8_t*
ArrayBufferViewObject::dataPointerUnshared(const JS::AutoRequireNoGC& nogc)
{
    if (is<DataViewObject>())
        return static_cast<uint8_t*>(as<DataViewObject>().dataPointer());
    if (is<TypedArrayObject>()) {
        MOZ_ASSERT(!as<TypedArrayObject>().isSharedMemory());
        return static_cast<uint8_t*>(as<TypedArrayObject>().viewDataUnshared());
    }
    return as<TypedObject>().typedMem(nogc);
}

#ifdef DEBUG
bool
ArrayBufferViewObject::isSharedMemory()
{
    if (is<TypedArrayObject>())
        return as<TypedArrayObject>().isSharedMemory();
    return false;
}
#endif

void
ArrayBufferViewObject::setDataPointerUnshared(uint8_t* data)
{
    if (is<DataViewObject>()) {
        as<DataViewObject>().setPrivate(data);
    } else if (is<TypedArrayObject>()) {
        MOZ_ASSERT(!as<TypedArrayObject>().isSharedMemory());
        as<TypedArrayObject>().setPrivate(data);
    } else if (is<OutlineTypedObject>()) {
        as<OutlineTypedObject>().setData(data);
    } else {
        MOZ_CRASH();
    }
}

/* static */ ArrayBufferObjectMaybeShared*
ArrayBufferViewObject::bufferObject(JSContext* cx, Handle<ArrayBufferViewObject*> thisObject)
{
    if (thisObject->is<TypedArrayObject>()) {
        Rooted<TypedArrayObject*> typedArray(cx, &thisObject->as<TypedArrayObject>());
        if (!TypedArrayObject::ensureHasBuffer(cx, typedArray))
            return nullptr;
        return thisObject->as<TypedArrayObject>().bufferEither();
    }
    MOZ_ASSERT(thisObject->is<DataViewObject>());
    return &thisObject->as<DataViewObject>().arrayBuffer();
}

/* JS Friend API */

JS_FRIEND_API(bool)
JS_IsArrayBufferViewObject(JSObject* obj)
{
    obj = CheckedUnwrap(obj);
    return obj && obj->is<ArrayBufferViewObject>();
}

JS_FRIEND_API(JSObject*)
js::UnwrapArrayBufferView(JSObject* obj)
{
    if (JSObject* unwrapped = CheckedUnwrap(obj))
        return unwrapped->is<ArrayBufferViewObject>() ? unwrapped : nullptr;
    return nullptr;
}

JS_FRIEND_API(uint32_t)
JS_GetArrayBufferByteLength(JSObject* obj)
{
    obj = CheckedUnwrap(obj);
    return obj ? AsArrayBuffer(obj).byteLength() : 0;
}

JS_FRIEND_API(uint8_t*)
JS_GetArrayBufferData(JSObject* obj, bool* isSharedMemory, const JS::AutoCheckCannotGC&)
{
    obj = CheckedUnwrap(obj);
    if (!obj)
        return nullptr;
    if (!IsArrayBuffer(obj))
        return nullptr;
    *isSharedMemory = false;
    return AsArrayBuffer(obj).dataPointer();
}

JS_FRIEND_API(bool)
JS_DetachArrayBuffer(JSContext* cx, HandleObject obj)
{
    AssertHeapIsIdle(cx);
    CHECK_REQUEST(cx);
    assertSameCompartment(cx, obj);

    if (!obj->is<ArrayBufferObject>()) {
        JS_ReportErrorASCII(cx, "ArrayBuffer object required");
        return false;
    }

    Rooted<ArrayBufferObject*> buffer(cx, &obj->as<ArrayBufferObject>());

    if (buffer->isWasm() || buffer->isPreparedForAsmJS()) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_NO_TRANSFER);
        return false;
    }

    ArrayBufferObject::BufferContents newContents =
        buffer->hasStealableContents() ? ArrayBufferObject::BufferContents::createPlain(nullptr)
                                       : buffer->contents();

    ArrayBufferObject::detach(cx, buffer, newContents);

    return true;
}

JS_FRIEND_API(bool)
JS_IsDetachedArrayBufferObject(JSObject* obj)
{
    obj = CheckedUnwrap(obj);
    if (!obj)
        return false;

    return obj->is<ArrayBufferObject>() && obj->as<ArrayBufferObject>().isDetached();
}

JS_FRIEND_API(JSObject*)
JS_NewArrayBuffer(JSContext* cx, uint32_t nbytes)
{
    AssertHeapIsIdle(cx);
    CHECK_REQUEST(cx);
    MOZ_ASSERT(nbytes <= INT32_MAX);
    return ArrayBufferObject::create(cx, nbytes);
}

JS_PUBLIC_API(JSObject*)
JS_NewArrayBufferWithContents(JSContext* cx, size_t nbytes, void* data)
{
    AssertHeapIsIdle(cx);
    CHECK_REQUEST(cx);
    MOZ_ASSERT_IF(!data, nbytes == 0);
    ArrayBufferObject::BufferContents contents =
        ArrayBufferObject::BufferContents::create<ArrayBufferObject::PLAIN>(data);
    return ArrayBufferObject::create(cx, nbytes, contents, ArrayBufferObject::OwnsData,
                                     /* proto = */ nullptr, TenuredObject);
}

JS_PUBLIC_API(JSObject*)
JS_NewArrayBufferWithExternalContents(JSContext* cx, size_t nbytes, void* data)
{
    AssertHeapIsIdle(cx);
    CHECK_REQUEST(cx);
    MOZ_ASSERT_IF(!data, nbytes == 0);
    ArrayBufferObject::BufferContents contents =
        ArrayBufferObject::BufferContents::create<ArrayBufferObject::PLAIN>(data);
    return ArrayBufferObject::create(cx, nbytes, contents, ArrayBufferObject::DoesntOwnData,
                                     /* proto = */ nullptr, TenuredObject);
}

JS_FRIEND_API(bool)
JS_IsArrayBufferObject(JSObject* obj)
{
    obj = CheckedUnwrap(obj);
    return obj && obj->is<ArrayBufferObject>();
}

JS_FRIEND_API(bool)
JS_ArrayBufferHasData(JSObject* obj)
{
    return CheckedUnwrap(obj)->as<ArrayBufferObject>().hasData();
}

JS_FRIEND_API(JSObject*)
js::UnwrapArrayBuffer(JSObject* obj)
{
    if (JSObject* unwrapped = CheckedUnwrap(obj))
        return unwrapped->is<ArrayBufferObject>() ? unwrapped : nullptr;
    return nullptr;
}

JS_FRIEND_API(JSObject*)
js::UnwrapSharedArrayBuffer(JSObject* obj)
{
    if (JSObject* unwrapped = CheckedUnwrap(obj))
        return unwrapped->is<SharedArrayBufferObject>() ? unwrapped : nullptr;
    return nullptr;
}

JS_PUBLIC_API(void*)
JS_ExternalizeArrayBufferContents(JSContext* cx, HandleObject obj)
{
    AssertHeapIsIdle(cx);
    CHECK_REQUEST(cx);
    assertSameCompartment(cx, obj);

    if (!obj->is<ArrayBufferObject>()) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_BAD_ARGS);
        return nullptr;
    }

    Handle<ArrayBufferObject*> buffer = obj.as<ArrayBufferObject>();
    if (!buffer->isPlain()) {
        // This operation isn't supported on mapped or wsm ArrayBufferObjects.
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_BAD_ARGS);
        return nullptr;
    }
    if (buffer->isDetached()) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED);
        return nullptr;
    }

    // The caller assumes that a plain malloc'd buffer is returned.
    // hasStealableContents is true for mapped buffers, so we must additionally
    // require that the buffer is plain. In the future, we could consider
    // returning something that handles releasing the memory.
    bool hasStealableContents = buffer->hasStealableContents();

    return ArrayBufferObject::externalizeContents(cx, buffer, hasStealableContents).data();
}

JS_PUBLIC_API(void*)
JS_StealArrayBufferContents(JSContext* cx, HandleObject objArg)
{
    AssertHeapIsIdle(cx);
    CHECK_REQUEST(cx);
    assertSameCompartment(cx, objArg);

    JSObject* obj = CheckedUnwrap(objArg);
    if (!obj)
        return nullptr;

    if (!obj->is<ArrayBufferObject>()) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_BAD_ARGS);
        return nullptr;
    }

    Rooted<ArrayBufferObject*> buffer(cx, &obj->as<ArrayBufferObject>());
    if (buffer->isDetached()) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED);
        return nullptr;
    }

    if (buffer->isWasm() || buffer->isPreparedForAsmJS()) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_WASM_NO_TRANSFER);
        return nullptr;
    }

    // The caller assumes that a plain malloc'd buffer is returned.
    // hasStealableContents is true for mapped buffers, so we must additionally
    // require that the buffer is plain. In the future, we could consider
    // returning something that handles releasing the memory.
    bool hasStealableContents = buffer->hasStealableContents() && buffer->isPlain();

    AutoCompartment ac(cx, buffer);
    return ArrayBufferObject::stealContents(cx, buffer, hasStealableContents).data();
}

JS_PUBLIC_API(JSObject*)
JS_NewMappedArrayBufferWithContents(JSContext* cx, size_t nbytes, void* data)
{
    AssertHeapIsIdle(cx);
    CHECK_REQUEST(cx);

    MOZ_ASSERT(data);
    ArrayBufferObject::BufferContents contents =
        ArrayBufferObject::BufferContents::create<ArrayBufferObject::MAPPED>(data);
    return ArrayBufferObject::create(cx, nbytes, contents, ArrayBufferObject::OwnsData,
                                     /* proto = */ nullptr, TenuredObject);
}

JS_PUBLIC_API(void*)
JS_CreateMappedArrayBufferContents(int fd, size_t offset, size_t length)
{
    return ArrayBufferObject::createMappedContents(fd, offset, length).data();
}

JS_PUBLIC_API(void)
JS_ReleaseMappedArrayBufferContents(void* contents, size_t length)
{
    MemProfiler::RemoveNative(contents);
    DeallocateMappedContent(contents, length);
}

JS_FRIEND_API(bool)
JS_IsMappedArrayBufferObject(JSObject* obj)
{
    obj = CheckedUnwrap(obj);
    if (!obj)
        return false;

    return obj->is<ArrayBufferObject>() && obj->as<ArrayBufferObject>().isMapped();
}

JS_FRIEND_API(void*)
JS_GetArrayBufferViewData(JSObject* obj, bool* isSharedMemory, const JS::AutoCheckCannotGC&)
{
    obj = CheckedUnwrap(obj);
    if (!obj)
        return nullptr;
    if (obj->is<DataViewObject>()) {
        *isSharedMemory = false;
        return obj->as<DataViewObject>().dataPointer();
    }
    TypedArrayObject& ta = obj->as<TypedArrayObject>();
    *isSharedMemory = ta.isSharedMemory();
    return ta.viewDataEither().unwrap(/*safe - caller sees isShared flag*/);
}

JS_FRIEND_API(JSObject*)
JS_GetArrayBufferViewBuffer(JSContext* cx, HandleObject objArg, bool* isSharedMemory)
{
    AssertHeapIsIdle(cx);
    CHECK_REQUEST(cx);
    assertSameCompartment(cx, objArg);

    JSObject* obj = CheckedUnwrap(objArg);
    if (!obj)
        return nullptr;
    MOZ_ASSERT(obj->is<ArrayBufferViewObject>());

    Rooted<ArrayBufferViewObject*> viewObject(cx, static_cast<ArrayBufferViewObject*>(obj));
    ArrayBufferObjectMaybeShared* buffer = ArrayBufferViewObject::bufferObject(cx, viewObject);
    *isSharedMemory = buffer->is<SharedArrayBufferObject>();
    return buffer;
}

JS_FRIEND_API(uint32_t)
JS_GetArrayBufferViewByteLength(JSObject* obj)
{
    obj = CheckedUnwrap(obj);
    if (!obj)
        return 0;
    return obj->is<DataViewObject>()
           ? obj->as<DataViewObject>().byteLength()
           : obj->as<TypedArrayObject>().byteLength();
}

JS_FRIEND_API(uint32_t)
JS_GetArrayBufferViewByteOffset(JSObject* obj)
{
    obj = CheckedUnwrap(obj);
    if (!obj)
        return 0;
    return obj->is<DataViewObject>()
           ? obj->as<DataViewObject>().byteOffset()
           : obj->as<TypedArrayObject>().byteOffset();
}

JS_FRIEND_API(JSObject*)
JS_GetObjectAsArrayBufferView(JSObject* obj, uint32_t* length, bool* isSharedMemory, uint8_t** data)
{
    if (!(obj = CheckedUnwrap(obj)))
        return nullptr;
    if (!(obj->is<ArrayBufferViewObject>()))
        return nullptr;

    js::GetArrayBufferViewLengthAndData(obj, length, isSharedMemory, data);
    return obj;
}

JS_FRIEND_API(void)
js::GetArrayBufferViewLengthAndData(JSObject* obj, uint32_t* length, bool* isSharedMemory, uint8_t** data)
{
    MOZ_ASSERT(obj->is<ArrayBufferViewObject>());

    *length = obj->is<DataViewObject>()
              ? obj->as<DataViewObject>().byteLength()
              : obj->as<TypedArrayObject>().byteLength();

    if (obj->is<DataViewObject>()) {
        *isSharedMemory = false;
        *data = static_cast<uint8_t*>(obj->as<DataViewObject>().dataPointer());
    }
    else {
        TypedArrayObject& ta = obj->as<TypedArrayObject>();
        *isSharedMemory = ta.isSharedMemory();
        *data = static_cast<uint8_t*>(ta.viewDataEither().unwrap(/*safe - caller sees isShared flag*/));
    }
}

JS_FRIEND_API(JSObject*)
JS_GetObjectAsArrayBuffer(JSObject* obj, uint32_t* length, uint8_t** data)
{
    if (!(obj = CheckedUnwrap(obj)))
        return nullptr;
    if (!IsArrayBuffer(obj))
        return nullptr;

    *length = AsArrayBuffer(obj).byteLength();
    *data = AsArrayBuffer(obj).dataPointer();

    return obj;
}

JS_FRIEND_API(void)
js::GetArrayBufferLengthAndData(JSObject* obj, uint32_t* length, bool* isSharedMemory, uint8_t** data)
{
    MOZ_ASSERT(IsArrayBuffer(obj));
    *length = AsArrayBuffer(obj).byteLength();
    *data = AsArrayBuffer(obj).dataPointer();
    *isSharedMemory = false;
}