DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (c3d72d38c09e)

VCS Links

Line Code
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 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "XrayWrapper.h"
#include "AccessCheck.h"
#include "WrapperFactory.h"

#include "nsDependentString.h"
#include "nsIScriptError.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/ScriptSettings.h"

#include "XPCWrapper.h"
#include "xpcprivate.h"

#include "jsapi.h"
#include "js/PropertySpec.h"
#include "nsJSUtils.h"
#include "nsPrintfCString.h"

#include "mozilla/FloatingPoint.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/BrowsingContext.h"
#include "mozilla/dom/WindowBinding.h"
#include "mozilla/dom/XrayExpandoClass.h"
#include "nsGlobalWindow.h"

using namespace mozilla::dom;
using namespace JS;
using namespace mozilla;

using js::BaseProxyHandler;
using js::CheckedUnwrapStatic;
using js::IsCrossCompartmentWrapper;
using js::UncheckedUnwrap;
using js::Wrapper;

namespace xpc {

using namespace XrayUtils;

#define Between(x, a, b) (a <= x && x <= b)

static_assert(JSProto_URIError - JSProto_Error == 7,
              "New prototype added in error object range");
#define AssertErrorObjectKeyInBounds(key)                      \
  static_assert(Between(key, JSProto_Error, JSProto_URIError), \
                "We depend on js/ProtoKey.h ordering here");
MOZ_FOR_EACH(AssertErrorObjectKeyInBounds, (),
             (JSProto_Error, JSProto_InternalError, JSProto_EvalError,
              JSProto_RangeError, JSProto_ReferenceError, JSProto_SyntaxError,
              JSProto_TypeError, JSProto_URIError));

static_assert(JSProto_Uint8ClampedArray - JSProto_Int8Array == 8,
              "New prototype added in typed array range");
#define AssertTypedArrayKeyInBounds(key)                                    \
  static_assert(Between(key, JSProto_Int8Array, JSProto_Uint8ClampedArray), \
                "We depend on js/ProtoKey.h ordering here");
MOZ_FOR_EACH(AssertTypedArrayKeyInBounds, (),
             (JSProto_Int8Array, JSProto_Uint8Array, JSProto_Int16Array,
              JSProto_Uint16Array, JSProto_Int32Array, JSProto_Uint32Array,
              JSProto_Float32Array, JSProto_Float64Array,
              JSProto_Uint8ClampedArray));

#undef Between

inline bool IsErrorObjectKey(JSProtoKey key) {
  return key >= JSProto_Error && key <= JSProto_URIError;
}

inline bool IsTypedArrayKey(JSProtoKey key) {
  return key >= JSProto_Int8Array && key <= JSProto_Uint8ClampedArray;
}

// Whitelist for the standard ES classes we can Xray to.
static bool IsJSXraySupported(JSProtoKey key) {
  if (IsTypedArrayKey(key)) {
    return true;
  }
  if (IsErrorObjectKey(key)) {
    return true;
  }
  switch (key) {
    case JSProto_Date:
    case JSProto_DataView:
    case JSProto_Object:
    case JSProto_Array:
    case JSProto_Function:
    case JSProto_TypedArray:
    case JSProto_SavedFrame:
    case JSProto_RegExp:
    case JSProto_Promise:
    case JSProto_ArrayBuffer:
    case JSProto_SharedArrayBuffer:
    case JSProto_Map:
    case JSProto_Set:
    case JSProto_WeakMap:
    case JSProto_WeakSet:
      return true;
    default:
      return false;
  }
}

XrayType GetXrayType(JSObject* obj) {
  obj = js::UncheckedUnwrap(obj, /* stopAtWindowProxy = */ false);
  if (mozilla::dom::UseDOMXray(obj)) {
    return XrayForDOMObject;
  }

  MOZ_ASSERT(!js::IsWindowProxy(obj));

  JSProtoKey standardProto = IdentifyStandardInstanceOrPrototype(obj);
  if (IsJSXraySupported(standardProto)) {
    return XrayForJSObject;
  }

  // Modulo a few exceptions, everything else counts as an XrayWrapper to an
  // opaque object, which means that more-privileged code sees nothing from
  // the underlying object. This is very important for security. In some cases
  // though, we need to make an exception for compatibility.
  if (IsSandbox(obj)) {
    return NotXray;
  }

  return XrayForOpaqueObject;
}

JSObject* XrayAwareCalleeGlobal(JSObject* fun) {
  MOZ_ASSERT(js::IsFunctionObject(fun));

  if (!js::FunctionHasNativeReserved(fun)) {
    // Just a normal function, no Xrays involved.
    return JS::GetNonCCWObjectGlobal(fun);
  }

  // The functions we expect here have the Xray wrapper they're associated with
  // in their XRAY_DOM_FUNCTION_PARENT_WRAPPER_SLOT and, in a debug build,
  // themselves in their XRAY_DOM_FUNCTION_NATIVE_SLOT_FOR_SELF.  Assert that
  // last bit.
  MOZ_ASSERT(&js::GetFunctionNativeReserved(
                  fun, XRAY_DOM_FUNCTION_NATIVE_SLOT_FOR_SELF)
                  .toObject() == fun);

  Value v =
      js::GetFunctionNativeReserved(fun, XRAY_DOM_FUNCTION_PARENT_WRAPPER_SLOT);
  MOZ_ASSERT(IsXrayWrapper(&v.toObject()));

  JSObject* xrayTarget = js::UncheckedUnwrap(&v.toObject());
  return JS::GetNonCCWObjectGlobal(xrayTarget);
}

JSObject* XrayTraits::getExpandoChain(HandleObject obj) {
  return ObjectScope(obj)->GetExpandoChain(obj);
}

JSObject* XrayTraits::detachExpandoChain(HandleObject obj) {
  return ObjectScope(obj)->DetachExpandoChain(obj);
}

bool XrayTraits::setExpandoChain(JSContext* cx, HandleObject obj,
                                 HandleObject chain) {
  return ObjectScope(obj)->SetExpandoChain(cx, obj, chain);
}

const JSClass XrayTraits::HolderClass = {
    "XrayHolder", JSCLASS_HAS_RESERVED_SLOTS(HOLDER_SHARED_SLOT_COUNT)};

const JSClass JSXrayTraits::HolderClass = {
    "JSXrayHolder", JSCLASS_HAS_RESERVED_SLOTS(SLOT_COUNT)};

bool OpaqueXrayTraits::resolveOwnProperty(
    JSContext* cx, HandleObject wrapper, HandleObject target,
    HandleObject holder, HandleId id, MutableHandle<PropertyDescriptor> desc) {
  bool ok =
      XrayTraits::resolveOwnProperty(cx, wrapper, target, holder, id, desc);
  if (!ok || desc.object()) {
    return ok;
  }

  return ReportWrapperDenial(cx, id, WrapperDenialForXray,
                             "object is not safely Xrayable");
}

bool ReportWrapperDenial(JSContext* cx, HandleId id, WrapperDenialType type,
                         const char* reason) {
  RealmPrivate* priv = RealmPrivate::Get(CurrentGlobalOrNull(cx));
  bool alreadyWarnedOnce = priv->wrapperDenialWarnings[type];
  priv->wrapperDenialWarnings[type] = true;

  // The browser console warning is only emitted for the first violation,
  // whereas the (debug-only) NS_WARNING is emitted for each violation.
#ifndef DEBUG
  if (alreadyWarnedOnce) {
    return true;
  }
#endif

  nsAutoJSString propertyName;
  RootedValue idval(cx);
  if (!JS_IdToValue(cx, id, &idval)) {
    return false;
  }
  JSString* str = JS_ValueToSource(cx, idval);
  if (!str) {
    return false;
  }
  if (!propertyName.init(cx, str)) {
    return false;
  }
  AutoFilename filename;
  unsigned line = 0, column = 0;
  DescribeScriptedCaller(cx, &filename, &line, &column);

  // Warn to the terminal for the logs.
  NS_WARNING(
      nsPrintfCString("Silently denied access to property %s: %s (@%s:%u:%u)",
                      NS_LossyConvertUTF16toASCII(propertyName).get(), reason,
                      filename.get(), line, column)
          .get());

  // If this isn't the first warning on this topic for this global, we've
  // already bailed out in opt builds. Now that the NS_WARNING is done, bail
  // out in debug builds as well.
  if (alreadyWarnedOnce) {
    return true;
  }

  //
  // Log a message to the console service.
  //

  // Grab the pieces.
  nsCOMPtr<nsIConsoleService> consoleService =
      do_GetService(NS_CONSOLESERVICE_CONTRACTID);
  NS_ENSURE_TRUE(consoleService, true);
  nsCOMPtr<nsIScriptError> errorObject =
      do_CreateInstance(NS_SCRIPTERROR_CONTRACTID);
  NS_ENSURE_TRUE(errorObject, true);

  // Compute the current window id if any.
  uint64_t windowId = 0;
  if (nsGlobalWindowInner* win = CurrentWindowOrNull(cx)) {
    windowId = win->WindowID();
  }

  Maybe<nsPrintfCString> errorMessage;
  if (type == WrapperDenialForXray) {
    errorMessage.emplace(
        "XrayWrapper denied access to property %s (reason: %s). "
        "See https://developer.mozilla.org/en-US/docs/Xray_vision "
        "for more information. Note that only the first denied "
        "property access from a given global object will be reported.",
        NS_LossyConvertUTF16toASCII(propertyName).get(), reason);
  } else {
    MOZ_ASSERT(type == WrapperDenialForCOW);
    errorMessage.emplace(
        "Security wrapper denied access to property %s on privileged "
        "Javascript object. Support for exposing privileged objects "
        "to untrusted content via __exposedProps__ has been "
        "removed - use WebIDL bindings or Components.utils.cloneInto "
        "instead. Note that only the first denied property access from a "
        "given global object will be reported.",
        NS_LossyConvertUTF16toASCII(propertyName).get());
  }
  nsString filenameStr(NS_ConvertASCIItoUTF16(filename.get()));
  nsresult rv = errorObject->InitWithWindowID(
      NS_ConvertASCIItoUTF16(errorMessage.ref()), filenameStr, EmptyString(),
      line, column, nsIScriptError::warningFlag, "XPConnect", windowId);
  NS_ENSURE_SUCCESS(rv, true);
  rv = consoleService->LogMessage(errorObject);
  NS_ENSURE_SUCCESS(rv, true);

  return true;
}

bool JSXrayTraits::getOwnPropertyFromWrapperIfSafe(
    JSContext* cx, HandleObject wrapper, HandleId id,
    MutableHandle<PropertyDescriptor> outDesc) {
  MOZ_ASSERT(js::IsObjectInContextCompartment(wrapper, cx));
  RootedObject target(cx, getTargetObject(wrapper));
  RootedObject wrapperGlobal(cx, JS::CurrentGlobalOrNull(cx));
  {
    JSAutoRealm ar(cx, target);
    JS_MarkCrossZoneId(cx, id);
    if (!getOwnPropertyFromTargetIfSafe(cx, target, wrapper, wrapperGlobal, id,
                                        outDesc)) {
      return false;
    }
  }
  return JS_WrapPropertyDescriptor(cx, outDesc);
}

bool JSXrayTraits::getOwnPropertyFromTargetIfSafe(
    JSContext* cx, HandleObject target, HandleObject wrapper,
    HandleObject wrapperGlobal, HandleId id,
    MutableHandle<PropertyDescriptor> outDesc) {
  // Note - This function operates in the target compartment, because it
  // avoids a bunch of back-and-forth wrapping in enumerateNames.
  MOZ_ASSERT(getTargetObject(wrapper) == target);
  MOZ_ASSERT(js::IsObjectInContextCompartment(target, cx));
  MOZ_ASSERT(WrapperFactory::IsXrayWrapper(wrapper));
  MOZ_ASSERT(JS_IsGlobalObject(wrapperGlobal));
  js::AssertSameCompartment(wrapper, wrapperGlobal);
  MOZ_ASSERT(outDesc.object() == nullptr);

  Rooted<PropertyDescriptor> desc(cx);
  if (!JS_GetOwnPropertyDescriptorById(cx, target, id, &desc)) {
    return false;
  }

  // If the property doesn't exist at all, we're done.
  if (!desc.object()) {
    return true;
  }

  // Disallow accessor properties.
  if (desc.hasGetterOrSetter()) {
    JSAutoRealm ar(cx, wrapperGlobal);
    JS_MarkCrossZoneId(cx, id);
    return ReportWrapperDenial(cx, id, WrapperDenialForXray,
                               "property has accessor");
  }

  // Apply extra scrutiny to objects.
  if (desc.value().isObject()) {
    RootedObject propObj(cx, js::UncheckedUnwrap(&desc.value().toObject()));
    JSAutoRealm ar(cx, propObj);

    // Disallow non-subsumed objects.
    if (!AccessCheck::subsumes(target, propObj)) {
      JSAutoRealm ar(cx, wrapperGlobal);
      JS_MarkCrossZoneId(cx, id);
      return ReportWrapperDenial(cx, id, WrapperDenialForXray,
                                 "value not same-origin with target");
    }

    // Disallow non-Xrayable objects.
    XrayType xrayType = GetXrayType(propObj);
    if (xrayType == NotXray || xrayType == XrayForOpaqueObject) {
      JSAutoRealm ar(cx, wrapperGlobal);
      JS_MarkCrossZoneId(cx, id);
      return ReportWrapperDenial(cx, id, WrapperDenialForXray,
                                 "value not Xrayable");
    }

    // Disallow callables.
    if (JS::IsCallable(propObj)) {
      JSAutoRealm ar(cx, wrapperGlobal);
      JS_MarkCrossZoneId(cx, id);
      return ReportWrapperDenial(cx, id, WrapperDenialForXray,
                                 "value is callable");
    }
  }

  // Disallow any property that shadows something on its (Xrayed)
  // prototype chain.
  JSAutoRealm ar2(cx, wrapperGlobal);
  JS_MarkCrossZoneId(cx, id);
  RootedObject proto(cx);
  bool foundOnProto = false;
  if (!JS_GetPrototype(cx, wrapper, &proto) ||
      (proto && !JS_HasPropertyById(cx, proto, id, &foundOnProto))) {
    return false;
  }
  if (foundOnProto) {
    return ReportWrapperDenial(
        cx, id, WrapperDenialForXray,
        "value shadows a property on the standard prototype");
  }

  // We made it! Assign over the descriptor, and don't forget to wrap.
  outDesc.assign(desc.get());
  return true;
}

// Returns true on success (in the JSAPI sense), false on failure.  If true is
// returned, desc.object() will indicate whether we actually resolved
// the property.
//
// id is the property id we're looking for.
// holder is the object to define the property on.
// fs is the relevant JSFunctionSpec*.
// ps is the relevant JSPropertySpec*.
// desc is the descriptor we're resolving into.
static bool TryResolvePropertyFromSpecs(
    JSContext* cx, HandleId id, HandleObject holder, const JSFunctionSpec* fs,
    const JSPropertySpec* ps, MutableHandle<PropertyDescriptor> desc) {
  // Scan through the functions.
  const JSFunctionSpec* fsMatch = nullptr;
  for (; fs && fs->name; ++fs) {
    if (PropertySpecNameEqualsId(fs->name, id)) {
      fsMatch = fs;
      break;
    }
  }
  if (fsMatch) {
    // Generate an Xrayed version of the method.
    RootedFunction fun(cx, JS::NewFunctionFromSpec(cx, fsMatch, id));
    if (!fun) {
      return false;
    }

    // The generic Xray machinery only defines non-own properties of the target
    // on the holder. This is broken, and will be fixed at some point, but for
    // now we need to cache the value explicitly. See the corresponding call to
    // JS_GetOwnPropertyDescriptorById at the top of
    // JSXrayTraits::resolveOwnProperty.
    RootedObject funObj(cx, JS_GetFunctionObject(fun));
    return JS_DefinePropertyById(cx, holder, id, funObj, 0) &&
           JS_GetOwnPropertyDescriptorById(cx, holder, id, desc);
  }

  // Scan through the properties.
  const JSPropertySpec* psMatch = nullptr;
  for (; ps && ps->name; ++ps) {
    if (PropertySpecNameEqualsId(ps->name, id)) {
      psMatch = ps;
      break;
    }
  }
  if (psMatch) {
    // The generic Xray machinery only defines non-own properties on the holder.
    // This is broken, and will be fixed at some point, but for now we need to
    // cache the value explicitly. See the corresponding call to
    // JS_GetPropertyById at the top of JSXrayTraits::resolveOwnProperty.
    //
    // Note also that the public-facing API here doesn't give us a way to
    // pass along JITInfo. It's probably ok though, since Xrays are already
    // pretty slow.
    desc.value().setUndefined();
    unsigned flags = psMatch->flags;
    if (psMatch->isAccessor()) {
      if (psMatch->isSelfHosted()) {
        JSFunction* getterFun = JS::GetSelfHostedFunction(
            cx, psMatch->u.accessors.getter.selfHosted.funname, id, 0);
        if (!getterFun) {
          return false;
        }
        RootedObject getterObj(cx, JS_GetFunctionObject(getterFun));
        RootedObject setterObj(cx);
        if (psMatch->u.accessors.setter.selfHosted.funname) {
          MOZ_ASSERT(flags & JSPROP_SETTER);
          JSFunction* setterFun = JS::GetSelfHostedFunction(
              cx, psMatch->u.accessors.setter.selfHosted.funname, id, 0);
          if (!setterFun) {
            return false;
          }
          setterObj = JS_GetFunctionObject(setterFun);
        }
        if (!JS_DefinePropertyById(cx, holder, id, getterObj, setterObj,
                                   flags)) {
          return false;
        }
      } else {
        if (!JS_DefinePropertyById(
                cx, holder, id, psMatch->u.accessors.getter.native.op,
                psMatch->u.accessors.setter.native.op, flags)) {
          return false;
        }
      }
    } else {
      RootedValue v(cx);
      if (!psMatch->getValue(cx, &v)) {
        return false;
      }
      if (!JS_DefinePropertyById(cx, holder, id, v,
                                 flags & ~JSPROP_INTERNAL_USE_BIT)) {
        return false;
      }
    }

    return JS_GetOwnPropertyDescriptorById(cx, holder, id, desc);
  }

  return true;
}

static bool ShouldResolvePrototypeProperty(JSProtoKey key) {
  // Proxy constructors have no "prototype" property.
  return key != JSProto_Proxy;
}

static bool ShouldResolveStaticProperties(JSProtoKey key) {
  if (!IsJSXraySupported(key)) {
    // If we can't Xray this ES class, then we can't resolve statics on it.
    return false;
  }

  // Don't try to resolve static properties on RegExp, because they
  // have issues.  In particular, some of them grab state off the
  // global of the RegExp constructor that describes the last regexp
  // evaluation in that global, which is not a useful thing to do
  // over Xrays.
  return key != JSProto_RegExp;
}

bool JSXrayTraits::resolveOwnProperty(JSContext* cx, HandleObject wrapper,
                                      HandleObject target, HandleObject holder,
                                      HandleId id,
                                      MutableHandle<PropertyDescriptor> desc) {
  // Call the common code.
  bool ok =
      XrayTraits::resolveOwnProperty(cx, wrapper, target, holder, id, desc);
  if (!ok || desc.object()) {
    return ok;
  }

  // The non-HasPrototypes semantics implemented by traditional Xrays are kind
  // of broken with respect to |own|-ness and the holder. The common code
  // muddles through by only checking the holder for non-|own| lookups, but
  // that doesn't work for us. So we do an explicit holder check here, and hope
  // that this mess gets fixed up soon.
  if (!JS_GetOwnPropertyDescriptorById(cx, holder, id, desc)) {
    return false;
  }
  if (desc.object()) {
    desc.object().set(wrapper);
    return true;
  }

  JSProtoKey key = getProtoKey(holder);
  if (!isPrototype(holder)) {
    // For Object and Array instances, we expose some properties from the
    // underlying object, but only after filtering them carefully.
    //
    // Note that, as far as JS observables go, Arrays are just Objects with
    // a different prototype and a magic (own, non-configurable) |.length| that
    // serves as a non-tight upper bound on |own| indexed properties. So while
    // it's tempting to try to impose some sort of structure on what Arrays
    // "should" look like over Xrays, the underlying object is squishy enough
    // that it makes sense to just treat them like Objects for Xray purposes.
    if (key == JSProto_Object || key == JSProto_Array) {
      return getOwnPropertyFromWrapperIfSafe(cx, wrapper, id, desc);
    }
    if (IsTypedArrayKey(key)) {
      if (IsArrayIndex(GetArrayIndexFromId(id))) {
        // WebExtensions can't use cloneInto(), so we just let them do
        // the slow thing to maximize compatibility.
        if (CompartmentPrivate::Get(CurrentGlobalOrNull(cx))
                ->isWebExtensionContentScript) {
          Rooted<PropertyDescriptor> innerDesc(cx);
          {
            JSAutoRealm ar(cx, target);
            JS_MarkCrossZoneId(cx, id);
            if (!JS_GetOwnPropertyDescriptorById(cx, target, id, &innerDesc)) {
              return false;
            }
          }
          if (innerDesc.isDataDescriptor() && innerDesc.value().isNumber()) {
            desc.setValue(innerDesc.value());
            desc.object().set(wrapper);
          }
          return true;
        }
        JS_ReportErrorASCII(
            cx,
            "Accessing TypedArray data over Xrays is slow, and forbidden "
            "in order to encourage performant code. To copy TypedArrays "
            "across origin boundaries, consider using "
            "Components.utils.cloneInto().");
        return false;
      }
    } else if (key == JSProto_Function) {
      if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_LENGTH)) {
        uint16_t length;
        RootedFunction fun(cx, JS_GetObjectFunction(target));
        {
          JSAutoRealm ar(cx, target);
          if (!JS_GetFunctionLength(cx, fun, &length)) {
            return false;
          }
        }
        FillPropertyDescriptor(desc, wrapper,
                               JSPROP_PERMANENT | JSPROP_READONLY,
                               NumberValue(length));
        return true;
      }
      if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_NAME)) {
        RootedString fname(cx, JS_GetFunctionId(JS_GetObjectFunction(target)));
        if (fname) {
          JS_MarkCrossZoneIdValue(cx, StringValue(fname));
        }
        FillPropertyDescriptor(
            desc, wrapper, JSPROP_PERMANENT | JSPROP_READONLY,
            fname ? StringValue(fname) : JS_GetEmptyStringValue(cx));
      } else {
        // Look for various static properties/methods and the
        // 'prototype' property.
        JSProtoKey standardConstructor = constructorFor(holder);
        if (standardConstructor != JSProto_Null) {
          // Handle the 'prototype' property to make
          // xrayedGlobal.StandardClass.prototype work.
          if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_PROTOTYPE) &&
              ShouldResolvePrototypeProperty(standardConstructor)) {
            RootedObject standardProto(cx);
            {
              JSAutoRealm ar(cx, target);
              if (!JS_GetClassPrototype(cx, standardConstructor,
                                        &standardProto)) {
                return false;
              }
              MOZ_ASSERT(standardProto);
            }

            if (!JS_WrapObject(cx, &standardProto)) {
              return false;
            }
            FillPropertyDescriptor(desc, wrapper,
                                   JSPROP_PERMANENT | JSPROP_READONLY,
                                   ObjectValue(*standardProto));
            return true;
          }

          if (ShouldResolveStaticProperties(standardConstructor)) {
            const js::Class* clasp = js::ProtoKeyToClass(standardConstructor);
            MOZ_ASSERT(clasp->specDefined());

            if (!TryResolvePropertyFromSpecs(
                    cx, id, holder, clasp->specConstructorFunctions(),
                    clasp->specConstructorProperties(), desc)) {
              return false;
            }

            if (desc.object()) {
              desc.object().set(wrapper);
              return true;
            }
          }
        }
      }
    } else if (IsErrorObjectKey(key)) {
      // The useful state of error objects (except for .stack) is
      // (unfortunately) represented as own data properties per-spec. This
      // means that we can't have a a clean representation of the data
      // (free from tampering) without doubling the slots of Error
      // objects, which isn't great. So we forward these properties to the
      // underlying object and then just censor any values with the wrong
      // type. This limits the ability of content to do anything all that
      // confusing.
      bool isErrorIntProperty =
          id == GetJSIDByIndex(cx, XPCJSContext::IDX_LINENUMBER) ||
          id == GetJSIDByIndex(cx, XPCJSContext::IDX_COLUMNNUMBER);
      bool isErrorStringProperty =
          id == GetJSIDByIndex(cx, XPCJSContext::IDX_FILENAME) ||
          id == GetJSIDByIndex(cx, XPCJSContext::IDX_MESSAGE);
      if (isErrorIntProperty || isErrorStringProperty) {
        RootedObject waiver(cx, wrapper);
        if (!WrapperFactory::WaiveXrayAndWrap(cx, &waiver)) {
          return false;
        }
        if (!JS_GetOwnPropertyDescriptorById(cx, waiver, id, desc)) {
          return false;
        }
        bool valueMatchesType =
            (isErrorIntProperty && desc.value().isInt32()) ||
            (isErrorStringProperty && desc.value().isString());
        if (desc.hasGetterOrSetter() || !valueMatchesType) {
          FillPropertyDescriptor(desc, nullptr, 0, UndefinedValue());
        }
        return true;
      }
    } else if (key == JSProto_RegExp) {
      if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_LASTINDEX)) {
        return getOwnPropertyFromWrapperIfSafe(cx, wrapper, id, desc);
      }
    }

    // The rest of this function applies only to prototypes.
    return true;
  }

  // Handle the 'constructor' property.
  if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_CONSTRUCTOR)) {
    RootedObject constructor(cx);
    {
      JSAutoRealm ar(cx, target);
      if (!JS_GetClassObject(cx, key, &constructor)) {
        return false;
      }
    }
    if (!JS_WrapObject(cx, &constructor)) {
      return false;
    }
    desc.object().set(wrapper);
    desc.setAttributes(0);
    desc.setGetter(nullptr);
    desc.setSetter(nullptr);
    desc.value().setObject(*constructor);
    return true;
  }

  if (ShouldIgnorePropertyDefinition(cx, key, id)) {
    MOZ_ASSERT(!desc.object());
    return true;
  }

  // Grab the JSClass. We require all Xrayable classes to have a ClassSpec.
  const js::Class* clasp = js::GetObjectClass(target);
  MOZ_ASSERT(clasp->specDefined());

  // Indexed array properties are handled above, so we can just work with the
  // class spec here.
  if (!TryResolvePropertyFromSpecs(cx, id, holder,
                                   clasp->specPrototypeFunctions(),
                                   clasp->specPrototypeProperties(), desc)) {
    return false;
  }

  if (desc.object()) {
    desc.object().set(wrapper);
  }

  return true;
}

bool JSXrayTraits::delete_(JSContext* cx, HandleObject wrapper, HandleId id,
                           ObjectOpResult& result) {
  MOZ_ASSERT(js::IsObjectInContextCompartment(wrapper, cx));

  RootedObject holder(cx, ensureHolder(cx, wrapper));
  if (!holder) {
    return false;
  }

  // If we're using Object Xrays, we allow callers to attempt to delete any
  // property from the underlying object that they are able to resolve. Note
  // that this deleting may fail if the property is non-configurable.
  JSProtoKey key = getProtoKey(holder);
  bool isObjectOrArrayInstance =
      (key == JSProto_Object || key == JSProto_Array) && !isPrototype(holder);
  if (isObjectOrArrayInstance) {
    RootedObject wrapperGlobal(cx, JS::CurrentGlobalOrNull(cx));
    RootedObject target(cx, getTargetObject(wrapper));
    JSAutoRealm ar(cx, target);
    JS_MarkCrossZoneId(cx, id);
    Rooted<PropertyDescriptor> desc(cx);
    if (!getOwnPropertyFromTargetIfSafe(cx, target, wrapper, wrapperGlobal, id,
                                        &desc)) {
      return false;
    }
    if (desc.object()) {
      return JS_DeletePropertyById(cx, target, id, result);
    }
  }
  return result.succeed();
}

bool JSXrayTraits::defineProperty(JSContext* cx, HandleObject wrapper,
                                  HandleId id, Handle<PropertyDescriptor> desc,
                                  Handle<PropertyDescriptor> existingDesc,
                                  ObjectOpResult& result, bool* defined) {
  *defined = false;
  RootedObject holder(cx, ensureHolder(cx, wrapper));
  if (!holder) {
    return false;
  }

  // Object and Array instances are special. For those cases, we forward
  // property definitions to the underlying object if the following
  // conditions are met:
  // * The property being defined is a value-prop.
  // * The property being defined is either a primitive or subsumed by the
  //   target.
  // * As seen from the Xray, any existing property that we would overwrite
  //   is an |own| value-prop.
  //
  // To avoid confusion, we disallow expandos on Object and Array instances, and
  // therefore raise an exception here if the above conditions aren't met.
  JSProtoKey key = getProtoKey(holder);
  bool isInstance = !isPrototype(holder);
  bool isObjectOrArray = (key == JSProto_Object || key == JSProto_Array);
  if (isObjectOrArray && isInstance) {
    RootedObject target(cx, getTargetObject(wrapper));
    if (desc.hasGetterOrSetter()) {
      JS_ReportErrorASCII(cx,
                          "Not allowed to define accessor property on [Object] "
                          "or [Array] XrayWrapper");
      return false;
    }
    if (desc.value().isObject() &&
        !AccessCheck::subsumes(target,
                               js::UncheckedUnwrap(&desc.value().toObject()))) {
      JS_ReportErrorASCII(cx,
                          "Not allowed to define cross-origin object as "
                          "property on [Object] or [Array] XrayWrapper");
      return false;
    }
    if (existingDesc.hasGetterOrSetter()) {
      JS_ReportErrorASCII(cx,
                          "Not allowed to overwrite accessor property on "
                          "[Object] or [Array] XrayWrapper");
      return false;
    }
    if (existingDesc.object() && existingDesc.object() != wrapper) {
      JS_ReportErrorASCII(cx,
                          "Not allowed to shadow non-own Xray-resolved "
                          "property on [Object] or [Array] XrayWrapper");
      return false;
    }

    Rooted<PropertyDescriptor> wrappedDesc(cx, desc);
    JSAutoRealm ar(cx, target);
    JS_MarkCrossZoneId(cx, id);
    if (!JS_WrapPropertyDescriptor(cx, &wrappedDesc) ||
        !JS_DefinePropertyById(cx, target, id, wrappedDesc, result)) {
      return false;
    }
    *defined = true;
    return true;
  }

  // For WebExtensions content scripts, we forward the definition of indexed
  // properties. By validating that the key and value are both numbers, we can
  // avoid doing any wrapping.
  if (isInstance && IsTypedArrayKey(key) &&
      CompartmentPrivate::Get(JS::CurrentGlobalOrNull(cx))
          ->isWebExtensionContentScript &&
      desc.isDataDescriptor() &&
      (desc.value().isNumber() || desc.value().isUndefined()) &&
      IsArrayIndex(GetArrayIndexFromId(id))) {
    RootedObject target(cx, getTargetObject(wrapper));
    JSAutoRealm ar(cx, target);
    JS_MarkCrossZoneId(cx, id);
    if (!JS_DefinePropertyById(cx, target, id, desc, result)) {
      return false;
    }
    *defined = true;
    return true;
  }

  return true;
}

static bool MaybeAppend(jsid id, unsigned flags, MutableHandleIdVector props) {
  MOZ_ASSERT(!(flags & JSITER_SYMBOLSONLY));
  if (!(flags & JSITER_SYMBOLS) && JSID_IS_SYMBOL(id)) {
    return true;
  }
  return props.append(id);
}

// Append the names from the given function and property specs to props.
static bool AppendNamesFromFunctionAndPropertySpecs(
    JSContext* cx, JSProtoKey key, const JSFunctionSpec* fs,
    const JSPropertySpec* ps, unsigned flags, MutableHandleIdVector props) {
  // Convert the method and property names to jsids and pass them to the caller.
  for (; fs && fs->name; ++fs) {
    jsid id;
    if (!PropertySpecNameToPermanentId(cx, fs->name, &id)) {
      return false;
    }
    if (!js::ShouldIgnorePropertyDefinition(cx, key, id)) {
      if (!MaybeAppend(id, flags, props)) {
        return false;
      }
    }
  }
  for (; ps && ps->name; ++ps) {
    jsid id;
    if (!PropertySpecNameToPermanentId(cx, ps->name, &id)) {
      return false;
    }
    if (!js::ShouldIgnorePropertyDefinition(cx, key, id)) {
      if (!MaybeAppend(id, flags, props)) {
        return false;
      }
    }
  }

  return true;
}

bool JSXrayTraits::enumerateNames(JSContext* cx, HandleObject wrapper,
                                  unsigned flags, MutableHandleIdVector props) {
  MOZ_ASSERT(js::IsObjectInContextCompartment(wrapper, cx));

  RootedObject target(cx, getTargetObject(wrapper));
  RootedObject holder(cx, ensureHolder(cx, wrapper));
  if (!holder) {
    return false;
  }

  JSProtoKey key = getProtoKey(holder);
  if (!isPrototype(holder)) {
    // For Object and Array instances, we expose some properties from the
    // underlying object, but only after filtering them carefully.
    if (key == JSProto_Object || key == JSProto_Array) {
      MOZ_ASSERT(props.empty());
      RootedObject wrapperGlobal(cx, JS::CurrentGlobalOrNull(cx));
      {
        JSAutoRealm ar(cx, target);
        RootedIdVector targetProps(cx);
        if (!js::GetPropertyKeys(cx, target, flags | JSITER_OWNONLY,
                                 &targetProps)) {
          return false;
        }
        // Loop over the properties, and only pass along the ones that
        // we determine to be safe.
        if (!props.reserve(targetProps.length())) {
          return false;
        }
        for (size_t i = 0; i < targetProps.length(); ++i) {
          Rooted<PropertyDescriptor> desc(cx);
          RootedId id(cx, targetProps[i]);
          if (!getOwnPropertyFromTargetIfSafe(cx, target, wrapper,
                                              wrapperGlobal, id, &desc)) {
            return false;
          }
          if (desc.object()) {
            props.infallibleAppend(id);
          }
        }
      }
      for (size_t i = 0; i < props.length(); ++i) {
        JS_MarkCrossZoneId(cx, props[i]);
      }
      return true;
    }
    if (IsTypedArrayKey(key)) {
      uint32_t length = JS_GetTypedArrayLength(target);
      // TypedArrays enumerate every indexed property in range, but
      // |length| is a getter that lives on the proto, like it should be.
      if (!props.reserve(length)) {
        return false;
      }
      for (int32_t i = 0; i <= int32_t(length - 1); ++i) {
        props.infallibleAppend(INT_TO_JSID(i));
      }
    } else if (key == JSProto_Function) {
      if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_LENGTH))) {
        return false;
      }
      if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_NAME))) {
        return false;
      }
      // Handle the .prototype property and static properties on standard
      // constructors.
      JSProtoKey standardConstructor = constructorFor(holder);
      if (standardConstructor != JSProto_Null) {
        if (ShouldResolvePrototypeProperty(standardConstructor)) {
          if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_PROTOTYPE))) {
            return false;
          }
        }

        if (ShouldResolveStaticProperties(standardConstructor)) {
          const js::Class* clasp = js::ProtoKeyToClass(standardConstructor);
          MOZ_ASSERT(clasp->specDefined());

          if (!AppendNamesFromFunctionAndPropertySpecs(
                  cx, key, clasp->specConstructorFunctions(),
                  clasp->specConstructorProperties(), flags, props)) {
            return false;
          }
        }
      }
    } else if (IsErrorObjectKey(key)) {
      if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_FILENAME)) ||
          !props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_LINENUMBER)) ||
          !props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_COLUMNNUMBER)) ||
          !props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_STACK)) ||
          !props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_MESSAGE))) {
        return false;
      }
    } else if (key == JSProto_RegExp) {
      if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_LASTINDEX))) {
        return false;
      }
    }

    // The rest of this function applies only to prototypes.
    return true;
  }

  // Add the 'constructor' property.
  if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_CONSTRUCTOR))) {
    return false;
  }

  // Grab the JSClass. We require all Xrayable classes to have a ClassSpec.
  const js::Class* clasp = js::GetObjectClass(target);
  MOZ_ASSERT(clasp->specDefined());

  return AppendNamesFromFunctionAndPropertySpecs(
      cx, key, clasp->specPrototypeFunctions(),
      clasp->specPrototypeProperties(), flags, props);
}

bool JSXrayTraits::construct(JSContext* cx, HandleObject wrapper,
                             const JS::CallArgs& args,
                             const js::Wrapper& baseInstance) {
  JSXrayTraits& self = JSXrayTraits::singleton;
  JS::RootedObject holder(cx, self.ensureHolder(cx, wrapper));
  if (!holder) {
    return false;
  }

  if (xpc::JSXrayTraits::getProtoKey(holder) == JSProto_Function) {
    JSProtoKey standardConstructor = constructorFor(holder);
    if (standardConstructor == JSProto_Null) {
      return baseInstance.construct(cx, wrapper, args);
    }

    const js::Class* clasp = js::ProtoKeyToClass(standardConstructor);
    MOZ_ASSERT(clasp);
    if (!(clasp->flags & JSCLASS_HAS_XRAYED_CONSTRUCTOR)) {
      return baseInstance.construct(cx, wrapper, args);
    }

    // If the JSCLASS_HAS_XRAYED_CONSTRUCTOR flag is set on the Class,
    // we don't use the constructor at hand. Instead, we retrieve the
    // equivalent standard constructor in the xray compartment and run
    // it in that compartment. The newTarget isn't unwrapped, and the
    // constructor has to be able to detect and handle this situation.
    // See the comments in js/public/Class.h and PromiseConstructor for
    // details and an example.
    RootedObject ctor(cx);
    if (!JS_GetClassObject(cx, standardConstructor, &ctor)) {
      return false;
    }

    RootedValue ctorVal(cx, ObjectValue(*ctor));
    HandleValueArray vals(args);
    RootedObject result(cx);
    if (!JS::Construct(cx, ctorVal, wrapper, vals, &result)) {
      return false;
    }
    AssertSameCompartment(cx, result);
    args.rval().setObject(*result);
    return true;
  }

  JS::RootedValue v(cx, JS::ObjectValue(*wrapper));
  js::ReportIsNotFunction(cx, v);
  return false;
}

JSObject* JSXrayTraits::createHolder(JSContext* cx, JSObject* wrapper) {
  RootedObject target(cx, getTargetObject(wrapper));
  RootedObject holder(cx,
                      JS_NewObjectWithGivenProto(cx, &HolderClass, nullptr));
  if (!holder) {
    return nullptr;
  }

  // Compute information about the target.
  bool isPrototype = false;
  JSProtoKey key = IdentifyStandardInstance(target);
  if (key == JSProto_Null) {
    isPrototype = true;
    key = IdentifyStandardPrototype(target);
  }
  MOZ_ASSERT(key != JSProto_Null);

  // Special case: pretend Arguments objects are arrays for Xrays.
  //
  // Arguments objects are strange beasts - they inherit Object.prototype,
  // and implement iteration by defining an |own| property for
  // Symbol.iterator. Since this value is callable, Array/Object Xrays will
  // filter it out, causing the Xray view to be non-iterable, which in turn
  // breaks consumers.
  //
  // We can't trust the iterator value from the content compartment,
  // but the generic one on Array.prototype works well enough. So we force
  // the Xray view of Arguments objects to inherit Array.prototype, which
  // in turn allows iteration via the inherited
  // Array.prototype[Symbol.iterator]. This doesn't emulate any of the weird
  // semantics of Arguments iterators, but is probably good enough.
  //
  // Note that there are various Xray traps that do other special behavior for
  // JSProto_Array, but they also provide that special behavior for
  // JSProto_Object, and since Arguments would otherwise get JSProto_Object,
  // this does not cause any behavior change at those sites.
  if (key == JSProto_Object && js::IsArgumentsObject(target)) {
    key = JSProto_Array;
  }

  // Store it on the holder.
  RootedValue v(cx);
  v.setNumber(static_cast<uint32_t>(key));
  js::SetReservedSlot(holder, SLOT_PROTOKEY, v);
  v.setBoolean(isPrototype);
  js::SetReservedSlot(holder, SLOT_ISPROTOTYPE, v);

  // If this is a function, also compute whether it serves as a constructor
  // for a standard class.
  if (key == JSProto_Function) {
    v.setNumber(static_cast<uint32_t>(IdentifyStandardConstructor(target)));
    js::SetReservedSlot(holder, SLOT_CONSTRUCTOR_FOR, v);
  }

  return holder;
}

DOMXrayTraits DOMXrayTraits::singleton;
JSXrayTraits JSXrayTraits::singleton;
OpaqueXrayTraits OpaqueXrayTraits::singleton;

XrayTraits* GetXrayTraits(JSObject* obj) {
  switch (GetXrayType(obj)) {
    case XrayForDOMObject:
      return &DOMXrayTraits::singleton;
    case XrayForJSObject:
      return &JSXrayTraits::singleton;
    case XrayForOpaqueObject:
      return &OpaqueXrayTraits::singleton;
    default:
      return nullptr;
  }
}

/*
 * Xray expando handling.
 *
 * We hang expandos for Xray wrappers off a reserved slot on the target object
 * so that same-origin compartments can share expandos for a given object. We
 * have a linked list of expando objects, one per origin. The properties on
 * these objects are generally wrappers pointing back to the compartment that
 * applied them.
 *
 * The expando objects should _never_ be exposed to script. The fact that they
 * live in the target compartment is a detail of the implementation, and does
 * not imply that code in the target compartment should be allowed to inspect
 * them. They are private to the origin that placed them.
 */

// Certain compartments do not share expandos with other compartments. Xrays in
// these compartments cache expandos on the wrapper's holder, as there is only
// one such wrapper which can create or access the expando. This allows for
// faster access to the expando, including through JIT inline caches.
static inline bool CompartmentHasExclusiveExpandos(JSObject* obj) {
  JS::Compartment* comp = js::GetObjectCompartment(obj);
  CompartmentPrivate* priv = CompartmentPrivate::Get(comp);
  return priv && priv->hasExclusiveExpandos;
}

static inline JSObject* GetCachedXrayExpando(JSObject* wrapper);

static inline void SetCachedXrayExpando(JSObject* holder,
                                        JSObject* expandoWrapper);

static nsIPrincipal* WrapperPrincipal(JSObject* obj) {
  // Use the principal stored in CompartmentOriginInfo. That works because
  // consumers are only interested in the origin-ignoring-document.domain.
  // See expandoObjectMatchesConsumer.
  MOZ_ASSERT(IsXrayWrapper(obj));
  JS::Compartment* comp = js::GetObjectCompartment(obj);
  CompartmentPrivate* priv = CompartmentPrivate::Get(comp);
  return priv->originInfo.GetPrincipalIgnoringDocumentDomain();
}

static nsIPrincipal* GetExpandoObjectPrincipal(JSObject* expandoObject) {
  Value v = JS_GetReservedSlot(expandoObject, JSSLOT_EXPANDO_ORIGIN);
  return static_cast<nsIPrincipal*>(v.toPrivate());
}

static void ExpandoObjectFinalize(JSFreeOp* fop, JSObject* obj) {
  // Release the principal.
  nsIPrincipal* principal = GetExpandoObjectPrincipal(obj);
  NS_RELEASE(principal);
}

const JSClassOps XrayExpandoObjectClassOps = {nullptr,
                                              nullptr,
                                              nullptr,
                                              nullptr,
                                              nullptr,
                                              nullptr,
                                              ExpandoObjectFinalize};

bool XrayTraits::expandoObjectMatchesConsumer(JSContext* cx,
                                              HandleObject expandoObject,
                                              nsIPrincipal* consumerOrigin) {
  MOZ_ASSERT(js::IsObjectInContextCompartment(expandoObject, cx));

  // First, compare the principals.
  nsIPrincipal* o = GetExpandoObjectPrincipal(expandoObject);
  // Note that it's very important here to ignore document.domain. We
  // pull the principal for the expando object off of the first consumer
  // for a given origin, and freely share the expandos amongst multiple
  // same-origin consumers afterwards. However, this means that we have
  // no way to know whether _all_ consumers have opted in to collaboration
  // by explicitly setting document.domain. So we just mandate that expando
  // sharing is unaffected by it.
  if (!consumerOrigin->Equals(o)) {
    return false;
  }

  // Certain globals exclusively own the associated expandos, in which case
  // the caller should have used the cached expando on the wrapper instead.
  JSObject* owner =
      JS_GetReservedSlot(expandoObject, JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER)
          .toObjectOrNull();
  return owner == nullptr;
}

bool XrayTraits::getExpandoObjectInternal(JSContext* cx, JSObject* expandoChain,
                                          HandleObject exclusiveWrapper,
                                          nsIPrincipal* origin,
                                          MutableHandleObject expandoObject) {
  MOZ_ASSERT(!JS_IsExceptionPending(cx));
  expandoObject.set(nullptr);

  // Use the cached expando if this wrapper has exclusive access to it.
  if (exclusiveWrapper) {
    JSObject* expandoWrapper = GetCachedXrayExpando(exclusiveWrapper);
    expandoObject.set(expandoWrapper ? UncheckedUnwrap(expandoWrapper)
                                     : nullptr);
#ifdef DEBUG
    // Make sure the expando we found is on the target's chain. While we
    // don't use this chain to look up expandos for the wrapper,
    // the expando still needs to be on the chain to keep the wrapper and
    // expando alive.
    if (expandoObject) {
      JSObject* head = expandoChain;
      while (head && head != expandoObject) {
        head = JS_GetReservedSlot(head, JSSLOT_EXPANDO_NEXT).toObjectOrNull();
      }
      MOZ_ASSERT(head == expandoObject);
    }
#endif
    return true;
  }

  // The expando object lives in the compartment of the target, so all our
  // work needs to happen there.
  RootedObject head(cx, expandoChain);
  JSAutoRealm ar(cx, head);

  // Iterate through the chain, looking for a same-origin object.
  while (head) {
    if (expandoObjectMatchesConsumer(cx, head, origin)) {
      expandoObject.set(head);
      return true;
    }
    head = JS_GetReservedSlot(head, JSSLOT_EXPANDO_NEXT).toObjectOrNull();
  }

  // Not found.
  return true;
}

bool XrayTraits::getExpandoObject(JSContext* cx, HandleObject target,
                                  HandleObject consumer,
                                  MutableHandleObject expandoObject) {
  // Return early if no expando object has ever been attached, which is
  // usually the case.
  JSObject* chain = getExpandoChain(target);
  if (!chain) {
    return true;
  }

  bool isExclusive = CompartmentHasExclusiveExpandos(consumer);
  return getExpandoObjectInternal(cx, chain, isExclusive ? consumer : nullptr,
                                  WrapperPrincipal(consumer), expandoObject);
}

// Wrappers which have exclusive access to the expando on their target object
// need to be kept alive as long as the target object exists. This is done by
// keeping the expando in the expando chain on the target (even though it will
// not be used while looking up the expando for the wrapper), and keeping a
// strong reference from that expando to the wrapper itself, via the
// JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER reserved slot. This slot does not
// point to the wrapper itself, because it is a cross compartment edge and we
// can't create a wrapper for a wrapper. Instead, the slot points to an
// instance of the holder class below in the wrapper's compartment, and the
// wrapper is held via this holder object's reserved slot.
static const JSClass gWrapperHolderClass = {"XrayExpandoWrapperHolder",
                                            JSCLASS_HAS_RESERVED_SLOTS(1)};
static const size_t JSSLOT_WRAPPER_HOLDER_CONTENTS = 0;

JSObject* XrayTraits::attachExpandoObject(JSContext* cx, HandleObject target,
                                          HandleObject exclusiveWrapper,
                                          HandleObject exclusiveWrapperGlobal,
                                          nsIPrincipal* origin) {
  // Make sure the compartments are sane.
  MOZ_ASSERT(js::IsObjectInContextCompartment(target, cx));
  if (exclusiveWrapper) {
    MOZ_ASSERT(!js::IsObjectInContextCompartment(exclusiveWrapper, cx));
    MOZ_ASSERT(JS_IsGlobalObject(exclusiveWrapperGlobal));
    js::AssertSameCompartment(exclusiveWrapper, exclusiveWrapperGlobal);
  }

  // No duplicates allowed.
#ifdef DEBUG
  {
    JSObject* chain = getExpandoChain(target);
    if (chain) {
      RootedObject existingExpandoObject(cx);
      if (getExpandoObjectInternal(cx, chain, exclusiveWrapper, origin,
                                   &existingExpandoObject)) {
        MOZ_ASSERT(!existingExpandoObject);
      } else {
        JS_ClearPendingException(cx);
      }
    }
  }
#endif

  // Create the expando object.
  const JSClass* expandoClass = getExpandoClass(cx, target);
  MOZ_ASSERT(!strcmp(expandoClass->name, "XrayExpandoObject"));
  RootedObject expandoObject(
      cx, JS_NewObjectWithGivenProto(cx, expandoClass, nullptr));
  if (!expandoObject) {
    return nullptr;
  }

  // AddRef and store the principal.
  NS_ADDREF(origin);
  JS_SetReservedSlot(expandoObject, JSSLOT_EXPANDO_ORIGIN,
                     JS::PrivateValue(origin));

  // Note the exclusive wrapper, if there is one.
  RootedObject wrapperHolder(cx);
  if (exclusiveWrapper) {
    JSAutoRealm ar(cx, exclusiveWrapperGlobal);
    wrapperHolder =
        JS_NewObjectWithGivenProto(cx, &gWrapperHolderClass, nullptr);
    if (!wrapperHolder) {
      return nullptr;
    }
    JS_SetReservedSlot(wrapperHolder, JSSLOT_WRAPPER_HOLDER_CONTENTS,
                       ObjectValue(*exclusiveWrapper));
  }
  if (!JS_WrapObject(cx, &wrapperHolder)) {
    return nullptr;
  }
  JS_SetReservedSlot(expandoObject, JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER,
                     ObjectOrNullValue(wrapperHolder));

  // Store it on the exclusive wrapper, if there is one.
  if (exclusiveWrapper) {
    RootedObject cachedExpandoObject(cx, expandoObject);
    JSAutoRealm ar(cx, exclusiveWrapperGlobal);
    if (!JS_WrapObject(cx, &cachedExpandoObject)) {
      return nullptr;
    }
    JSObject* holder = ensureHolder(cx, exclusiveWrapper);
    if (!holder) {
      return nullptr;
    }
    SetCachedXrayExpando(holder, cachedExpandoObject);
  }

  // If this is our first expando object, take the opportunity to preserve
  // the wrapper. This keeps our expandos alive even if the Xray wrapper gets
  // collected.
  RootedObject chain(cx, getExpandoChain(target));
  if (!chain) {
    preserveWrapper(target);
  }

  // Insert it at the front of the chain.
  JS_SetReservedSlot(expandoObject, JSSLOT_EXPANDO_NEXT,
                     ObjectOrNullValue(chain));
  setExpandoChain(cx, target, expandoObject);

  return expandoObject;
}

JSObject* XrayTraits::ensureExpandoObject(JSContext* cx, HandleObject wrapper,
                                          HandleObject target) {
  MOZ_ASSERT(js::IsObjectInContextCompartment(wrapper, cx));
  RootedObject wrapperGlobal(cx, JS::CurrentGlobalOrNull(cx));

  // Expando objects live in the target compartment.
  JSAutoRealm ar(cx, target);
  RootedObject expandoObject(cx);
  if (!getExpandoObject(cx, target, wrapper, &expandoObject)) {
    return nullptr;
  }
  if (!expandoObject) {
    bool isExclusive = CompartmentHasExclusiveExpandos(wrapper);
    expandoObject =
        attachExpandoObject(cx, target, isExclusive ? wrapper : nullptr,
                            wrapperGlobal, WrapperPrincipal(wrapper));
  }
  return expandoObject;
}

bool XrayTraits::cloneExpandoChain(JSContext* cx, HandleObject dst,
                                   HandleObject srcChain) {
  MOZ_ASSERT(js::IsObjectInContextCompartment(dst, cx));
  MOZ_ASSERT(getExpandoChain(dst) == nullptr);

  RootedObject oldHead(cx, srcChain);
  while (oldHead) {
    // If movingIntoXrayCompartment is true, then our new reflector is in a
    // compartment that used to have an Xray-with-expandos to the old reflector
    // and we should copy the expandos to the new reflector directly.
    bool movingIntoXrayCompartment;

    // exclusiveWrapper is only used if movingIntoXrayCompartment ends up true.
    RootedObject exclusiveWrapper(cx);
    RootedObject exclusiveWrapperGlobal(cx);
    RootedObject wrapperHolder(
        cx, JS_GetReservedSlot(oldHead, JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER)
                .toObjectOrNull());
    if (wrapperHolder) {
      RootedObject unwrappedHolder(cx, UncheckedUnwrap(wrapperHolder));
      // unwrappedHolder is the compartment of the relevant Xray, so check
      // whether that matches the compartment of cx (which matches the
      // compartment of dst).
      movingIntoXrayCompartment =
          js::IsObjectInContextCompartment(unwrappedHolder, cx);

      if (!movingIntoXrayCompartment) {
        // The global containing this wrapper holder has an xray for |src|
        // with expandos. Create an xray in the global for |dst| which
        // will be associated with a clone of |src|'s expando object.
        JSAutoRealm ar(cx, unwrappedHolder);
        exclusiveWrapper = dst;
        if (!JS_WrapObject(cx, &exclusiveWrapper)) {
          return false;
        }
        exclusiveWrapperGlobal = JS::CurrentGlobalOrNull(cx);
      }
    } else {
      JSAutoRealm ar(cx, oldHead);
      movingIntoXrayCompartment =
          expandoObjectMatchesConsumer(cx, oldHead, GetObjectPrincipal(dst));
    }

    if (movingIntoXrayCompartment) {
      // Just copy properties directly onto dst.
      if (!JS_CopyPropertiesFrom(cx, dst, oldHead)) {
        return false;
      }
    } else {
      // Create a new expando object in the compartment of dst to replace
      // oldHead.
      RootedObject newHead(
          cx,
          attachExpandoObject(cx, dst, exclusiveWrapper, exclusiveWrapperGlobal,
                              GetExpandoObjectPrincipal(oldHead)));
      if (!JS_CopyPropertiesFrom(cx, newHead, oldHead)) {
        return false;
      }
    }
    oldHead = JS_GetReservedSlot(oldHead, JSSLOT_EXPANDO_NEXT).toObjectOrNull();
  }
  return true;
}

void ClearXrayExpandoSlots(JSObject* target, size_t slotIndex) {
  if (!NS_IsMainThread()) {
    // No Xrays
    return;
  }

  MOZ_ASSERT(slotIndex != JSSLOT_EXPANDO_NEXT);
  MOZ_ASSERT(slotIndex != JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER);
  MOZ_ASSERT(GetXrayTraits(target) == &DOMXrayTraits::singleton);
  RootingContext* rootingCx = RootingCx();
  RootedObject rootedTarget(rootingCx, target);
  RootedObject head(rootingCx,
                    DOMXrayTraits::singleton.getExpandoChain(rootedTarget));
  while (head) {
    MOZ_ASSERT(JSCLASS_RESERVED_SLOTS(js::GetObjectClass(head)) > slotIndex);
    js::SetReservedSlot(head, slotIndex, UndefinedValue());
    head = js::GetReservedSlot(head, JSSLOT_EXPANDO_NEXT).toObjectOrNull();
  }
}

JSObject* EnsureXrayExpandoObject(JSContext* cx, JS::HandleObject wrapper) {
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(GetXrayTraits(wrapper) == &DOMXrayTraits::singleton);
  MOZ_ASSERT(IsXrayWrapper(wrapper));

  RootedObject target(cx, DOMXrayTraits::getTargetObject(wrapper));
  return DOMXrayTraits::singleton.ensureExpandoObject(cx, wrapper, target);
}

const JSClass* XrayTraits::getExpandoClass(JSContext* cx,
                                           HandleObject target) const {
  return &DefaultXrayExpandoObjectClass;
}

static const size_t JSSLOT_XRAY_HOLDER = 0;

/* static */
JSObject* XrayTraits::getHolder(JSObject* wrapper) {
  MOZ_ASSERT(WrapperFactory::IsXrayWrapper(wrapper));
  js::Value v = js::GetProxyReservedSlot(wrapper, JSSLOT_XRAY_HOLDER);
  return v.isObject() ? &v.toObject() : nullptr;
}

JSObject* XrayTraits::ensureHolder(JSContext* cx, HandleObject wrapper) {
  RootedObject holder(cx, getHolder(wrapper));
  if (holder) {
    return holder;
  }
  holder = createHolder(cx, wrapper);  // virtual trap.
  if (holder) {
    js::SetProxyReservedSlot(wrapper, JSSLOT_XRAY_HOLDER, ObjectValue(*holder));
  }
  return holder;
}

static inline JSObject* GetCachedXrayExpando(JSObject* wrapper) {
  JSObject* holder = XrayTraits::getHolder(wrapper);
  if (!holder) {
    return nullptr;
  }
  Value v = JS_GetReservedSlot(holder, XrayTraits::HOLDER_SLOT_EXPANDO);
  return v.isObject() ? &v.toObject() : nullptr;
}

static inline void SetCachedXrayExpando(JSObject* holder,
                                        JSObject* expandoWrapper) {
  MOZ_ASSERT(js::GetObjectCompartment(holder) ==
             js::GetObjectCompartment(expandoWrapper));
  JS_SetReservedSlot(holder, XrayTraits::HOLDER_SLOT_EXPANDO,
                     ObjectValue(*expandoWrapper));
}

static nsGlobalWindowInner* AsWindow(JSContext* cx, JSObject* wrapper) {
  // We want to use our target object here, since we don't want to be
  // doing a security check while unwrapping.
  JSObject* target = XrayTraits::getTargetObject(wrapper);
  return WindowOrNull(target);
}

static bool IsWindow(JSContext* cx, JSObject* wrapper) {
  return !!AsWindow(cx, wrapper);
}

static bool wrappedJSObject_getter(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  if (!args.thisv().isObject()) {
    JS_ReportErrorASCII(cx, "This value not an object");
    return false;
  }
  RootedObject wrapper(cx, &args.thisv().toObject());
  if (!IsWrapper(wrapper) || !WrapperFactory::IsXrayWrapper(wrapper) ||
      !WrapperFactory::AllowWaiver(wrapper)) {
    JS_ReportErrorASCII(cx, "Unexpected object");
    return false;
  }

  args.rval().setObject(*wrapper);

  return WrapperFactory::WaiveXrayAndWrap(cx, args.rval());
}

bool XrayTraits::resolveOwnProperty(JSContext* cx, HandleObject wrapper,
                                    HandleObject target, HandleObject holder,
                                    HandleId id,
                                    MutableHandle<PropertyDescriptor> desc) {
  desc.object().set(nullptr);
  RootedObject expando(cx);
  if (!getExpandoObject(cx, target, wrapper, &expando)) {
    return false;
  }

  // Check for expando properties first. Note that the expando object lives
  // in the target compartment.
  bool found = false;
  if (expando) {
    JSAutoRealm ar(cx, expando);
    JS_MarkCrossZoneId(cx, id);
    if (!JS_GetOwnPropertyDescriptorById(cx, expando, id, desc)) {
      return false;
    }
    found = !!desc.object();
  }

  // Next, check for ES builtins.
  if (!found && JS_IsGlobalObject(target)) {
    JSProtoKey key = JS_IdToProtoKey(cx, id);
    JSAutoRealm ar(cx, target);
    if (key != JSProto_Null) {
      MOZ_ASSERT(key < JSProto_LIMIT);
      RootedObject constructor(cx);
      if (!JS_GetClassObject(cx, key, &constructor)) {
        return false;
      }
      MOZ_ASSERT(constructor);
      desc.value().set(ObjectValue(*constructor));
      found = true;
    } else if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_EVAL)) {
      RootedObject eval(cx);
      if (!js::GetRealmOriginalEval(cx, &eval)) {
        return false;
      }
      desc.value().set(ObjectValue(*eval));
      found = true;
    } else if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_INFINITY)) {
      desc.value().setNaN();
      desc.setAttributes(JSPROP_PERMANENT | JSPROP_READONLY);
      found = true;
    } else if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_NAN)) {
      desc.value().setDouble(PositiveInfinity<double>());
      desc.setAttributes(JSPROP_PERMANENT | JSPROP_READONLY);
      found = true;
    }
  }

  if (found) {
    if (!JS_WrapPropertyDescriptor(cx, desc)) {
      return false;
    }
    // Pretend the property lives on the wrapper.
    desc.object().set(wrapper);
    return true;
  }

  // Handle .wrappedJSObject for subsuming callers. This should move once we
  // sort out own-ness for the holder.
  if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_WRAPPED_JSOBJECT) &&
      WrapperFactory::AllowWaiver(wrapper)) {
    if (!JS_AlreadyHasOwnPropertyById(cx, holder, id, &found)) {
      return false;
    }
    if (!found && !JS_DefinePropertyById(cx, holder, id, wrappedJSObject_getter,
                                         nullptr, JSPROP_ENUMERATE)) {
      return false;
    }
    if (!JS_GetOwnPropertyDescriptorById(cx, holder, id, desc)) {
      return false;
    }
    desc.object().set(wrapper);
    return true;
  }

  return true;
}

bool DOMXrayTraits::resolveOwnProperty(JSContext* cx, HandleObject wrapper,
                                       HandleObject target, HandleObject holder,
                                       HandleId id,
                                       MutableHandle<PropertyDescriptor> desc) {
  // Call the common code.
  bool ok =
      XrayTraits::resolveOwnProperty(cx, wrapper, target, holder, id, desc);
  if (!ok || desc.object()) {
    return ok;
  }

  // Check for indexed access on a window.
  uint32_t index = GetArrayIndexFromId(id);
  if (IsArrayIndex(index)) {
    nsGlobalWindowInner* win = AsWindow(cx, wrapper);
    // Note: As() unwraps outer windows to get to the inner window.
    if (win) {
      nsCOMPtr<nsPIDOMWindowOuter> subframe = win->IndexedGetter(index);
      if (subframe) {
        subframe->EnsureInnerWindow();
        nsGlobalWindowOuter* global = nsGlobalWindowOuter::Cast(subframe);
        JSObject* obj = global->GetGlobalJSObject();
        if (MOZ_UNLIKELY(!obj)) {
          // It's gone?
          return xpc::Throw(cx, NS_ERROR_FAILURE);
        }
        desc.value().setObject(*obj);
        FillPropertyDescriptor(desc, wrapper, true);
        return JS_WrapPropertyDescriptor(cx, desc);
      }
    }
  }

  if (!JS_GetOwnPropertyDescriptorById(cx, holder, id, desc)) {
    return false;
  }
  if (desc.object()) {
    desc.object().set(wrapper);
    return true;
  }

  bool cacheOnHolder;
  if (!XrayResolveOwnProperty(cx, wrapper, target, id, desc, cacheOnHolder)) {
    return false;
  }

  MOZ_ASSERT(!desc.object() || desc.object() == wrapper,
             "What did we resolve this on?");

  if (!desc.object() || !cacheOnHolder) {
    return true;
  }

  return JS_DefinePropertyById(cx, holder, id, desc) &&
         JS_GetOwnPropertyDescriptorById(cx, holder, id, desc);
}

bool DOMXrayTraits::delete_(JSContext* cx, JS::HandleObject wrapper,
                            JS::HandleId id, JS::ObjectOpResult& result) {
  RootedObject target(cx, getTargetObject(wrapper));
  return XrayDeleteNamedProperty(cx, wrapper, target, id, result);
}

bool DOMXrayTraits::defineProperty(JSContext* cx, HandleObject wrapper,
                                   HandleId id, Handle<PropertyDescriptor> desc,
                                   Handle<PropertyDescriptor> existingDesc,
                                   JS::ObjectOpResult& result, bool* defined) {
  // Check for an indexed property on a Window.  If that's happening, do
  // nothing but claim we defined it so it won't get added as an expando.
  if (IsWindow(cx, wrapper)) {
    if (IsArrayIndex(GetArrayIndexFromId(id))) {
      *defined = true;
      return result.succeed();
    }
  }

  JS::Rooted<JSObject*> obj(cx, getTargetObject(wrapper));
  return XrayDefineProperty(cx, wrapper, obj, id, desc, result, defined);
}

bool DOMXrayTraits::enumerateNames(JSContext* cx, HandleObject wrapper,
                                   unsigned flags,
                                   MutableHandleIdVector props) {
  // Put the indexed properties for a window first.
  nsGlobalWindowInner* win = AsWindow(cx, wrapper);
  if (win) {
    uint32_t length = win->Length();
    if (!props.reserve(props.length() + length)) {
      return false;
    }
    JS::RootedId indexId(cx);
    for (uint32_t i = 0; i < length; ++i) {
      if (!JS_IndexToId(cx, i, &indexId)) {
        return false;
      }
      props.infallibleAppend(indexId);
    }
  }

  JS::Rooted<JSObject*> obj(cx, getTargetObject(wrapper));
  if (JS_IsGlobalObject(obj)) {
    // We could do this in a shared enumerateNames with JSXrayTraits, but we
    // don't really have globals we expose via those.
    JSAutoRealm ar(cx, obj);
    if (!JS_NewEnumerateStandardClassesIncludingResolved(
            cx, obj, props, !(flags & JSITER_HIDDEN))) {
      return false;
    }
  }
  return XrayOwnPropertyKeys(cx, wrapper, obj, flags, props);
}

bool DOMXrayTraits::call(JSContext* cx, HandleObject wrapper,
                         const JS::CallArgs& args,
                         const js::Wrapper& baseInstance) {
  RootedObject obj(cx, getTargetObject(wrapper));
  const js::Class* clasp = js::GetObjectClass(obj);
  // What we have is either a WebIDL interface object, a WebIDL prototype
  // object, or a WebIDL instance object.  WebIDL prototype objects never have
  // a clasp->call.  WebIDL interface objects we want to invoke on the xray
  // compartment.  WebIDL instance objects either don't have a clasp->call or
  // are using "legacycaller", which basically means plug-ins.  We want to
  // call those on the content compartment.
  if (clasp->flags & JSCLASS_IS_DOMIFACEANDPROTOJSCLASS) {
    if (JSNative call = clasp->getCall()) {
      // call it on the Xray compartment
      if (!call(cx, args.length(), args.base())) {
        return false;
      }
    } else {
      RootedValue v(cx, ObjectValue(*wrapper));
      js::ReportIsNotFunction(cx, v);
      return false;
    }
  } else {
    // This is only reached for WebIDL instance objects, and in practice
    // only for plugins.  Just call them on the content compartment.
    if (!baseInstance.call(cx, wrapper, args)) {
      return false;
    }
  }
  return JS_WrapValue(cx, args.rval());
}

bool DOMXrayTraits::construct(JSContext* cx, HandleObject wrapper,
                              const JS::CallArgs& args,
                              const js::Wrapper& baseInstance) {
  RootedObject obj(cx, getTargetObject(wrapper));
  MOZ_ASSERT(mozilla::dom::HasConstructor(obj));
  const js::Class* clasp = js::GetObjectClass(obj);
  // See comments in DOMXrayTraits::call() explaining what's going on here.
  if (clasp->flags & JSCLASS_IS_DOMIFACEANDPROTOJSCLASS) {
    if (JSNative construct = clasp->getConstruct()) {
      if (!construct(cx, args.length(), args.base())) {
        return false;
      }
    } else {
      RootedValue v(cx, ObjectValue(*wrapper));
      js::ReportIsNotFunction(cx, v);
      return false;
    }
  } else {
    if (!baseInstance.construct(cx, wrapper, args)) {
      return false;
    }
  }
  if (!args.rval().isObject() || !JS_WrapValue(cx, args.rval())) {
    return false;
  }
  return true;
}

bool DOMXrayTraits::getPrototype(JSContext* cx, JS::HandleObject wrapper,
                                 JS::HandleObject target,
                                 JS::MutableHandleObject protop) {
  return mozilla::dom::XrayGetNativeProto(cx, target, protop);
}

void DOMXrayTraits::preserveWrapper(JSObject* target) {
  nsISupports* identity = mozilla::dom::UnwrapDOMObjectToISupports(target);
  if (!identity) {
    return;
  }
  nsWrapperCache* cache = nullptr;
  CallQueryInterface(identity, &cache);
  if (cache) {
    cache->PreserveWrapper(identity);
  }
}

JSObject* DOMXrayTraits::createHolder(JSContext* cx, JSObject* wrapper) {
  return JS_NewObjectWithGivenProto(cx, &HolderClass, nullptr);
}

const JSClass* DOMXrayTraits::getExpandoClass(JSContext* cx,
                                              HandleObject target) const {
  return XrayGetExpandoClass(cx, target);
}

namespace XrayUtils {

bool HasNativeProperty(JSContext* cx, HandleObject wrapper, HandleId id,
                       bool* hasProp) {
  MOZ_ASSERT(WrapperFactory::IsXrayWrapper(wrapper));
  XrayTraits* traits = GetXrayTraits(wrapper);
  MOZ_ASSERT(traits);
  RootedObject target(cx, XrayTraits::getTargetObject(wrapper));
  RootedObject holder(cx, traits->ensureHolder(cx, wrapper));
  NS_ENSURE_TRUE(holder, false);
  *hasProp = false;
  Rooted<PropertyDescriptor> desc(cx);

  // Try resolveOwnProperty.
  if (!traits->resolveOwnProperty(cx, wrapper, target, holder, id, &desc)) {
    return false;
  }
  if (desc.object()) {
    *hasProp = true;
    return true;
  }

  // Try the holder.
  return JS_AlreadyHasOwnPropertyById(cx, holder, id, hasProp);
}

}  // namespace XrayUtils

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::preventExtensions(
    JSContext* cx, HandleObject wrapper, ObjectOpResult& result) const {
  // Xray wrappers are supposed to provide a clean view of the target
  // reflector, hiding any modifications by script in the target scope.  So
  // even if that script freezes the reflector, we don't want to make that
  // visible to the caller. DOM reflectors are always extensible by default,
  // so we can just return failure here.
  return result.failCantPreventExtensions();
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::isExtensible(JSContext* cx,
                                             JS::Handle<JSObject*> wrapper,
                                             bool* extensible) const {
  // See above.
  *extensible = true;
  return true;
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::getOwnPropertyDescriptor(
    JSContext* cx, HandleObject wrapper, HandleId id,
    JS::MutableHandle<PropertyDescriptor> desc) const {
  assertEnteredPolicy(cx, wrapper, id,
                      BaseProxyHandler::GET | BaseProxyHandler::SET |
                          BaseProxyHandler::GET_PROPERTY_DESCRIPTOR);
  RootedObject target(cx, Traits::getTargetObject(wrapper));
  RootedObject holder(cx, Traits::singleton.ensureHolder(cx, wrapper));
  if (!holder) {
    return false;
  }

  if (!Traits::singleton.resolveOwnProperty(cx, wrapper, target, holder, id,
                                            desc)) {
    return false;
  }
  if (desc.object()) {
    desc.object().set(wrapper);
  }
  return true;
}

// Consider what happens when chrome does |xray.expando = xray.wrappedJSObject|.
//
// Since the expando comes from the target compartment, wrapping it back into
// the target compartment to define it on the expando object ends up stripping
// off the Xray waiver that gives |xray| and |xray.wrappedJSObject| different
// identities. This is generally the right thing to do when wrapping across
// compartments, but is incorrect in the special case of the Xray expando
// object. Manually re-apply Xrays if necessary.
//
// NB: In order to satisfy the invariants of WaiveXray, we need to pass
// in an object sans security wrapper, which means we need to strip off any
// potential same-compartment security wrapper that may have been applied
// to the content object. This is ok, because the the expando object is only
// ever accessed by code across the compartment boundary.
static bool RecreateLostWaivers(JSContext* cx, const PropertyDescriptor* orig,
                                MutableHandle<PropertyDescriptor> wrapped) {
  // Compute whether the original objects were waived, and implicitly, whether
  // they were objects at all.
  bool valueWasWaived =
      orig->value.isObject() &&
      WrapperFactory::HasWaiveXrayFlag(&orig->value.toObject());
  bool getterWasWaived = (orig->attrs & JSPROP_GETTER) && orig->getter &&
                         WrapperFactory::HasWaiveXrayFlag(
                             JS_FUNC_TO_DATA_PTR(JSObject*, orig->getter));
  bool setterWasWaived = (orig->attrs & JSPROP_SETTER) && orig->setter &&
                         WrapperFactory::HasWaiveXrayFlag(
                             JS_FUNC_TO_DATA_PTR(JSObject*, orig->setter));

  // Recreate waivers. Note that for value, we need an extra UncheckedUnwrap
  // to handle same-compartment security wrappers (see above). This should
  // never happen for getters/setters.

  RootedObject rewaived(cx);
  if (valueWasWaived &&
      !IsCrossCompartmentWrapper(&wrapped.value().toObject())) {
    rewaived = &wrapped.value().toObject();
    rewaived = WrapperFactory::WaiveXray(cx, UncheckedUnwrap(rewaived));
    NS_ENSURE_TRUE(rewaived, false);
    wrapped.value().set(ObjectValue(*rewaived));
  }
  if (getterWasWaived && !IsCrossCompartmentWrapper(wrapped.getterObject())) {
    // We can't end up with WindowProxy or Location as getters.
    MOZ_ASSERT(CheckedUnwrapStatic(wrapped.getterObject()));
    rewaived = WrapperFactory::WaiveXray(cx, wrapped.getterObject());
    NS_ENSURE_TRUE(rewaived, false);
    wrapped.setGetterObject(rewaived);
  }
  if (setterWasWaived && !IsCrossCompartmentWrapper(wrapped.setterObject())) {
    // We can't end up with WindowProxy or Location as setters.
    MOZ_ASSERT(CheckedUnwrapStatic(wrapped.setterObject()));
    rewaived = WrapperFactory::WaiveXray(cx, wrapped.setterObject());
    NS_ENSURE_TRUE(rewaived, false);
    wrapped.setSetterObject(rewaived);
  }

  return true;
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::defineProperty(JSContext* cx,
                                               HandleObject wrapper,
                                               HandleId id,
                                               Handle<PropertyDescriptor> desc,
                                               ObjectOpResult& result) const {
  assertEnteredPolicy(cx, wrapper, id, BaseProxyHandler::SET);

  Rooted<PropertyDescriptor> existing_desc(cx);
  if (!JS_GetPropertyDescriptorById(cx, wrapper, id, &existing_desc)) {
    return false;
  }

  // Note that the check here is intended to differentiate between own and
  // non-own properties, since the above lookup is not limited to own
  // properties. At present, this may not always do the right thing because
  // we often lie (sloppily) about where we found properties and set
  // desc.object() to |wrapper|. Once we fully fix our Xray prototype semantics,
  // this should work as intended.
  if (existing_desc.object() == wrapper && !existing_desc.configurable()) {
    // We have a non-configurable property. See if the caller is trying to
    // re-configure it in any way other than making it non-writable.
    if (existing_desc.isAccessorDescriptor() || desc.isAccessorDescriptor() ||
        (desc.hasEnumerable() &&
         existing_desc.enumerable() != desc.enumerable()) ||
        (desc.hasWritable() && !existing_desc.writable() && desc.writable())) {
      // We should technically report non-configurability in strict mode, but
      // doing that via JSAPI used to be a lot of trouble. See bug 1135997.
      return result.succeed();
    }
    if (!existing_desc.writable()) {
      // Same as the above for non-writability.
      return result.succeed();
    }
  }

  bool defined = false;
  if (!Traits::singleton.defineProperty(cx, wrapper, id, desc, existing_desc,
                                        result, &defined)) {
    return false;
  }
  if (defined) {
    return true;
  }

  // Grab the relevant expando object.
  RootedObject target(cx, Traits::getTargetObject(wrapper));
  RootedObject expandoObject(
      cx, Traits::singleton.ensureExpandoObject(cx, wrapper, target));
  if (!expandoObject) {
    return false;
  }

  // We're placing an expando. The expando objects live in the target
  // compartment, so we need to enter it.
  JSAutoRealm ar(cx, target);
  JS_MarkCrossZoneId(cx, id);

  // Wrap the property descriptor for the target compartment.
  Rooted<PropertyDescriptor> wrappedDesc(cx, desc);
  if (!JS_WrapPropertyDescriptor(cx, &wrappedDesc)) {
    return false;
  }

  // Fix up Xray waivers.
  if (!RecreateLostWaivers(cx, desc.address(), &wrappedDesc)) {
    return false;
  }

  return JS_DefinePropertyById(cx, expandoObject, id, wrappedDesc, result);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::ownPropertyKeys(
    JSContext* cx, HandleObject wrapper, MutableHandleIdVector props) const {
  assertEnteredPolicy(cx, wrapper, JSID_VOID, BaseProxyHandler::ENUMERATE);
  return getPropertyKeys(
      cx, wrapper, JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS, props);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::delete_(JSContext* cx, HandleObject wrapper,
                                        HandleId id,
                                        ObjectOpResult& result) const {
  assertEnteredPolicy(cx, wrapper, id, BaseProxyHandler::SET);

  // Check the expando object.
  RootedObject target(cx, Traits::getTargetObject(wrapper));
  RootedObject expando(cx);
  if (!Traits::singleton.getExpandoObject(cx, target, wrapper, &expando)) {
    return false;
  }

  if (expando) {
    JSAutoRealm ar(cx, expando);
    JS_MarkCrossZoneId(cx, id);
    bool hasProp;
    if (!JS_HasPropertyById(cx, expando, id, &hasProp)) {
      return false;
    }
    if (hasProp) {
      return JS_DeletePropertyById(cx, expando, id, result);
    }
  }

  return Traits::singleton.delete_(cx, wrapper, id, result);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::get(JSContext* cx, HandleObject wrapper,
                                    HandleValue receiver, HandleId id,
                                    MutableHandleValue vp) const {
  // This is called by Proxy::get, but since we return true for hasPrototype()
  // it's only called for properties that hasOwn() claims we have as own
  // properties.  Since we only need to worry about own properties, we can use
  // getOwnPropertyDescriptor here.
  Rooted<PropertyDescriptor> desc(cx);
  if (!getOwnPropertyDescriptor(cx, wrapper, id, &desc)) {
    return false;
  }
  desc.assertCompleteIfFound();

  MOZ_ASSERT(desc.object(),
             "hasOwn() claimed we have this property, so why would we not get "
             "a descriptor here?");

  // Everything after here follows [[Get]] for ordinary objects.
  if (desc.isDataDescriptor()) {
    vp.set(desc.value());
    return true;
  }

  MOZ_ASSERT(desc.isAccessorDescriptor());
  RootedObject getter(cx, desc.getterObject());

  if (!getter) {
    vp.setUndefined();
    return true;
  }

  return Call(cx, receiver, getter, HandleValueArray::empty(), vp);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::set(JSContext* cx, HandleObject wrapper,
                                    HandleId id, HandleValue v,
                                    HandleValue receiver,
                                    ObjectOpResult& result) const {
  MOZ_CRASH("Shouldn't be called: we return true for hasPrototype()");
  return false;
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::has(JSContext* cx, HandleObject wrapper,
                                    HandleId id, bool* bp) const {
  MOZ_CRASH("Shouldn't be called: we return true for hasPrototype()");
  return false;
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::hasOwn(JSContext* cx, HandleObject wrapper,
                                       HandleId id, bool* bp) const {
  // Skip our Base if it isn't already ProxyHandler.
  return js::BaseProxyHandler::hasOwn(cx, wrapper, id, bp);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::getOwnEnumerablePropertyKeys(
    JSContext* cx, HandleObject wrapper, MutableHandleIdVector props) const {
  // Skip our Base if it isn't already ProxyHandler.
  return js::BaseProxyHandler::getOwnEnumerablePropertyKeys(cx, wrapper, props);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::enumerate(
    JSContext* cx, HandleObject wrapper,
    JS::MutableHandleIdVector props) const {
  MOZ_CRASH("Shouldn't be called: we return true for hasPrototype()");
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::call(JSContext* cx, HandleObject wrapper,
                                     const JS::CallArgs& args) const {
  assertEnteredPolicy(cx, wrapper, JSID_VOID, BaseProxyHandler::CALL);
  // Hard cast the singleton since SecurityWrapper doesn't have one.
  return Traits::call(cx, wrapper, args, Base::singleton);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::construct(JSContext* cx, HandleObject wrapper,
                                          const JS::CallArgs& args) const {
  assertEnteredPolicy(cx, wrapper, JSID_VOID, BaseProxyHandler::CALL);
  // Hard cast the singleton since SecurityWrapper doesn't have one.
  return Traits::construct(cx, wrapper, args, Base::singleton);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::getBuiltinClass(JSContext* cx,
                                                JS::HandleObject wrapper,
                                                js::ESClass* cls) const {
  return Traits::getBuiltinClass(cx, wrapper, Base::singleton, cls);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::hasInstance(JSContext* cx,
                                            JS::HandleObject wrapper,
                                            JS::MutableHandleValue v,
                                            bool* bp) const {
  assertEnteredPolicy(cx, wrapper, JSID_VOID, BaseProxyHandler::GET);

  // CrossCompartmentWrapper::hasInstance unwraps |wrapper|'s Xrays and enters
  // its compartment. Any present XrayWrappers should be preserved, so the
  // standard "instanceof" implementation is called without unwrapping first.
  return JS::InstanceofOperator(cx, wrapper, v, bp);
}

template <typename Base, typename Traits>
const char* XrayWrapper<Base, Traits>::className(JSContext* cx,
                                                 HandleObject wrapper) const {
  return Traits::className(cx, wrapper, Base::singleton);
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::getPrototype(
    JSContext* cx, JS::HandleObject wrapper,
    JS::MutableHandleObject protop) const {
  // We really only want this override for non-SecurityWrapper-inheriting
  // |Base|. But doing that statically with templates requires partial method
  // specializations (and therefore a helper class), which is all more trouble
  // than it's worth. Do a dynamic check.
  if (Base::hasSecurityPolicy()) {
    return Base::getPrototype(cx, wrapper, protop);
  }

  RootedObject target(cx, Traits::getTargetObject(wrapper));
  RootedObject expando(cx);
  if (!Traits::singleton.getExpandoObject(cx, target, wrapper, &expando)) {
    return false;
  }

  // We want to keep the Xray's prototype distinct from that of content, but
  // only if there's been a set. If there's not an expando, or the expando
  // slot is |undefined|, hand back the default proto, appropriately wrapped.

  if (expando) {
    RootedValue v(cx);
    {  // Scope for JSAutoRealm
      JSAutoRealm ar(cx, expando);
      v = JS_GetReservedSlot(expando, JSSLOT_EXPANDO_PROTOTYPE);
    }
    if (!v.isUndefined()) {
      protop.set(v.toObjectOrNull());
      return JS_WrapObject(cx, protop);
    }
  }

  // Check our holder, and cache there if we don't have it cached already.
  RootedObject holder(cx, Traits::singleton.ensureHolder(cx, wrapper));
  if (!holder) {
    return false;
  }

  Value cached = js::GetReservedSlot(holder, Traits::HOLDER_SLOT_CACHED_PROTO);
  if (cached.isUndefined()) {
    if (!Traits::singleton.getPrototype(cx, wrapper, target, protop)) {
      return false;
    }

    js::SetReservedSlot(holder, Traits::HOLDER_SLOT_CACHED_PROTO,
                        ObjectOrNullValue(protop));
  } else {
    protop.set(cached.toObjectOrNull());
  }
  return true;
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::setPrototype(JSContext* cx,
                                             JS::HandleObject wrapper,
                                             JS::HandleObject proto,
                                             JS::ObjectOpResult& result) const {
  // Do this only for non-SecurityWrapper-inheriting |Base|. See the comment
  // in getPrototype().
  if (Base::hasSecurityPolicy()) {
    return Base::setPrototype(cx, wrapper, proto, result);
  }

  RootedObject target(cx, Traits::getTargetObject(wrapper));
  RootedObject expando(
      cx, Traits::singleton.ensureExpandoObject(cx, wrapper, target));
  if (!expando) {
    return false;
  }

  // The expando lives in the target's realm, so do our installation there.
  JSAutoRealm ar(cx, target);

  RootedValue v(cx, ObjectOrNullValue(proto));
  if (!JS_WrapValue(cx, &v)) {
    return false;
  }
  JS_SetReservedSlot(expando, JSSLOT_EXPANDO_PROTOTYPE, v);
  return result.succeed();
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::getPrototypeIfOrdinary(
    JSContext* cx, JS::HandleObject wrapper, bool* isOrdinary,
    JS::MutableHandleObject protop) const {
  // We want to keep the Xray's prototype distinct from that of content, but
  // only if there's been a set.  This different-prototype-over-time behavior
  // means that the [[GetPrototypeOf]] trap *can't* be ECMAScript's ordinary
  // [[GetPrototypeOf]].  This also covers cross-origin Window behavior that
  // per
  // <https://html.spec.whatwg.org/multipage/browsers.html#windowproxy-getprototypeof>
  // must be non-ordinary.
  *isOrdinary = false;
  return true;
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::setImmutablePrototype(JSContext* cx,
                                                      JS::HandleObject wrapper,
                                                      bool* succeeded) const {
  // For now, lacking an obvious place to store a bit, prohibit making an
  // Xray's [[Prototype]] immutable.  We can revisit this (or maybe give all
  // Xrays immutable [[Prototype]], because who does this, really?) later if
  // necessary.
  *succeeded = false;
  return true;
}

template <typename Base, typename Traits>
bool XrayWrapper<Base, Traits>::getPropertyKeys(
    JSContext* cx, HandleObject wrapper, unsigned flags,
    MutableHandleIdVector props) const {
  assertEnteredPolicy(cx, wrapper, JSID_VOID, BaseProxyHandler::ENUMERATE);

  // Enumerate expando properties first. Note that the expando object lives
  // in the target compartment.
  RootedObject target(cx, Traits::getTargetObject(wrapper));
  RootedObject expando(cx);
  if (!Traits::singleton.getExpandoObject(cx, target, wrapper, &expando)) {
    return false;
  }

  if (expando) {
    JSAutoRealm ar(cx, expando);
    if (!js::GetPropertyKeys(cx, expando, flags, props)) {
      return false;
    }
  }
  for (size_t i = 0; i < props.length(); ++i) {
    JS_MarkCrossZoneId(cx, props[i]);
  }

  return Traits::singleton.enumerateNames(cx, wrapper, flags, props);
}

/*
 * The Permissive / Security variants should be used depending on whether the
 * compartment of the wrapper is guranteed to subsume the compartment of the
 * wrapped object (i.e. - whether it is safe from a security perspective to
 * unwrap the wrapper).
 */

template <typename Base, typename Traits>
const xpc::XrayWrapper<Base, Traits> xpc::XrayWrapper<Base, Traits>::singleton(
    0);

template class PermissiveXrayDOM;
template class PermissiveXrayJS;
template class PermissiveXrayOpaque;

/*
 * This callback is used by the JS engine to test if a proxy handler is for a
 * cross compartment xray with no security requirements.
 */
static bool IsCrossCompartmentXrayCallback(
    const js::BaseProxyHandler* handler) {
  return handler == &PermissiveXrayDOM::singleton;
}

js::XrayJitInfo gXrayJitInfo = {
    IsCrossCompartmentXrayCallback, CompartmentHasExclusiveExpandos,
    JSSLOT_XRAY_HOLDER, XrayTraits::HOLDER_SLOT_EXPANDO,
    JSSLOT_EXPANDO_PROTOTYPE};

}  // namespace xpc