summaryrefslogtreecommitdiff
path: root/uriloader/exthandler/nsExternalHelperAppService.cpp
blob: 698090718f0ec2e08714fa1f81ee9634405aecf2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
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
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * 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 "base/basictypes.h"

/* This must occur *after* base/basictypes.h to avoid typedefs conflicts. */
#include "mozilla/ArrayUtils.h"
#include "mozilla/Base64.h"

#include "mozilla/dom/ContentChild.h"
#include "mozilla/dom/TabChild.h"
#include "nsXULAppAPI.h"

#include "nsExternalHelperAppService.h"
#include "nsCExternalHandlerService.h"
#include "nsIURI.h"
#include "nsIURL.h"
#include "nsIFile.h"
#include "nsIFileURL.h"
#include "nsIChannel.h"
#include "nsIDirectoryService.h"
#include "nsAppDirectoryServiceDefs.h"
#include "nsICategoryManager.h"
#include "nsDependentSubstring.h"
#include "nsXPIDLString.h"
#include "nsUnicharUtils.h"
#include "nsIStringEnumerator.h"
#include "nsMemory.h"
#include "nsIStreamListener.h"
#include "nsIMIMEService.h"
#include "nsILoadGroup.h"
#include "nsIWebProgressListener.h"
#include "nsITransfer.h"
#include "nsReadableUtils.h"
#include "nsIRequest.h"
#include "nsDirectoryServiceDefs.h"
#include "nsIInterfaceRequestor.h"
#include "nsThreadUtils.h"
#include "nsAutoPtr.h"
#include "nsIMutableArray.h"

// used to access our datastore of user-configured helper applications
#include "nsIHandlerService.h"
#include "nsIMIMEInfo.h"
#include "nsIRefreshURI.h" // XXX needed to redirect according to Refresh: URI
#include "nsIDocumentLoader.h" // XXX needed to get orig. channel and assoc. refresh uri
#include "nsIHelperAppLauncherDialog.h"
#include "nsIContentDispatchChooser.h"
#include "nsNetUtil.h"
#include "nsIPrivateBrowsingChannel.h"
#include "nsIIOService.h"
#include "nsNetCID.h"

#include "nsMimeTypes.h"
// used for header disposition information.
#include "nsIHttpChannel.h"
#include "nsIHttpChannelInternal.h"
#include "nsIEncodedChannel.h"
#include "nsIMultiPartChannel.h"
#include "nsIFileChannel.h"
#include "nsIObserverService.h" // so we can be a profile change observer
#include "nsIPropertyBag2.h" // for the 64-bit content length

#ifdef XP_MACOSX
#include "nsILocalFileMac.h"
#endif

#include "nsIPluginHost.h" // XXX needed for ext->type mapping (bug 233289)
#include "nsPluginHost.h"
#include "nsEscape.h"

#include "nsIStringBundle.h" // XXX needed to localize error msgs
#include "nsIPrompt.h"

#include "nsITextToSubURI.h" // to unescape the filename
#include "nsIMIMEHeaderParam.h"

#include "nsIWindowWatcher.h"

#include "nsIDownloadHistory.h" // to mark downloads as visited
#include "nsDocShellCID.h"

#include "nsCRT.h"
#include "nsLocalHandlerApp.h"

#include "nsIRandomGenerator.h"

#include "ContentChild.h"
#include "nsXULAppAPI.h"
#include "nsPIDOMWindow.h"
#include "nsIDocShellTreeOwner.h"
#include "nsIDocShellTreeItem.h"
#include "ExternalHelperAppChild.h"

#ifdef XP_WIN
#include "nsWindowsHelpers.h"
#endif

#include "mozilla/Preferences.h"
#include "mozilla/ipc/URIUtils.h"

using namespace mozilla;
using namespace mozilla::ipc;

// Download Folder location constants
#define NS_PREF_DOWNLOAD_DIR        "browser.download.dir"
#define NS_PREF_DOWNLOAD_FOLDERLIST "browser.download.folderList"
enum {
  NS_FOLDER_VALUE_DESKTOP = 0
, NS_FOLDER_VALUE_DOWNLOADS = 1
, NS_FOLDER_VALUE_CUSTOM = 2
};

LazyLogModule nsExternalHelperAppService::mLog("HelperAppService");

// Using level 3 here because the OSHelperAppServices use a log level
// of LogLevel::Debug (4), and we want less detailed output here
// Using 3 instead of LogLevel::Warning because we don't output warnings
#undef LOG
#define LOG(args) MOZ_LOG(nsExternalHelperAppService::mLog, mozilla::LogLevel::Info, args)
#define LOG_ENABLED() MOZ_LOG_TEST(nsExternalHelperAppService::mLog, mozilla::LogLevel::Info)

static const char NEVER_ASK_FOR_SAVE_TO_DISK_PREF[] =
  "browser.helperApps.neverAsk.saveToDisk";
static const char NEVER_ASK_FOR_OPEN_FILE_PREF[] =
  "browser.helperApps.neverAsk.openFile";

// Helper functions for Content-Disposition headers

/**
 * Given a URI fragment, unescape it
 * @param aFragment The string to unescape
 * @param aURI The URI from which this fragment is taken. Only its character set
 *             will be used.
 * @param aResult [out] Unescaped string.
 */
static nsresult UnescapeFragment(const nsACString& aFragment, nsIURI* aURI,
                                 nsAString& aResult)
{
  // First, we need a charset
  nsAutoCString originCharset;
  nsresult rv = aURI->GetOriginCharset(originCharset);
  NS_ENSURE_SUCCESS(rv, rv);

  // Now, we need the unescaper
  nsCOMPtr<nsITextToSubURI> textToSubURI = do_GetService(NS_ITEXTTOSUBURI_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  return textToSubURI->UnEscapeURIForUI(originCharset, aFragment, aResult);
}

/**
 * UTF-8 version of UnescapeFragment.
 * @param aFragment The string to unescape
 * @param aURI The URI from which this fragment is taken. Only its character set
 *             will be used.
 * @param aResult [out] Unescaped string, UTF-8 encoded.
 * @note It is safe to pass the same string for aFragment and aResult.
 * @note When this function fails, aResult will not be modified.
 */
static nsresult UnescapeFragment(const nsACString& aFragment, nsIURI* aURI,
                                 nsACString& aResult)
{
  nsAutoString result;
  nsresult rv = UnescapeFragment(aFragment, aURI, result);
  if (NS_SUCCEEDED(rv))
    CopyUTF16toUTF8(result, aResult);
  return rv;
}

/**
 * Given a channel, returns the filename and extension the channel has.
 * This uses the URL and other sources (nsIMultiPartChannel).
 * Also gives back whether the channel requested external handling (i.e.
 * whether Content-Disposition: attachment was sent)
 * @param aChannel The channel to extract the filename/extension from
 * @param aFileName [out] Reference to the string where the filename should be
 *        stored. Empty if it could not be retrieved.
 *        WARNING - this filename may contain characters which the OS does not
 *        allow as part of filenames!
 * @param aExtension [out] Reference to the string where the extension should
 *        be stored. Empty if it could not be retrieved. Stored in UTF-8.
 * @param aAllowURLExtension (optional) Get the extension from the URL if no
 *        Content-Disposition header is present. Default is true.
 * @retval true The server sent Content-Disposition:attachment or equivalent
 * @retval false Content-Disposition: inline or no content-disposition header
 *         was sent.
 */
static bool GetFilenameAndExtensionFromChannel(nsIChannel* aChannel,
                                                 nsString& aFileName,
                                                 nsCString& aExtension,
                                                 bool aAllowURLExtension = true)
{
  aExtension.Truncate();
  /*
   * If the channel is an http or part of a multipart channel and we
   * have a content disposition header set, then use the file name
   * suggested there as the preferred file name to SUGGEST to the
   * user.  we shouldn't actually use that without their
   * permission... otherwise just use our temp file
   */
  bool handleExternally = false;
  uint32_t disp;
  nsresult rv = aChannel->GetContentDisposition(&disp);
  if (NS_SUCCEEDED(rv))
  {
    aChannel->GetContentDispositionFilename(aFileName);
    if (disp == nsIChannel::DISPOSITION_ATTACHMENT)
      handleExternally = true;
  }

  // If the disposition header didn't work, try the filename from nsIURL
  nsCOMPtr<nsIURI> uri;
  aChannel->GetURI(getter_AddRefs(uri));
  nsCOMPtr<nsIURL> url(do_QueryInterface(uri));
  if (url && aFileName.IsEmpty())
  {
    if (aAllowURLExtension) {
      url->GetFileExtension(aExtension);
      UnescapeFragment(aExtension, url, aExtension);

      // Windows ignores terminating dots. So we have to as well, so
      // that our security checks do "the right thing"
      // In case the aExtension consisted only of the dot, the code below will
      // extract an aExtension from the filename
      aExtension.Trim(".", false);
    }

    // try to extract the file name from the url and use that as a first pass as the
    // leaf name of our temp file...
    nsAutoCString leafName;
    url->GetFileName(leafName);
    if (!leafName.IsEmpty())
    {
      rv = UnescapeFragment(leafName, url, aFileName);
      if (NS_FAILED(rv))
      {
        CopyUTF8toUTF16(leafName, aFileName); // use escaped name
      }
    }
  }

  // Extract Extension, if we have a filename; otherwise,
  // truncate the string
  if (aExtension.IsEmpty()) {
    if (!aFileName.IsEmpty())
    {
      // Windows ignores terminating dots. So we have to as well, so
      // that our security checks do "the right thing"
      aFileName.Trim(".", false);

      // XXX RFindCharInReadable!!
      nsAutoString fileNameStr(aFileName);
      int32_t idx = fileNameStr.RFindChar(char16_t('.'));
      if (idx != kNotFound)
        CopyUTF16toUTF8(StringTail(fileNameStr, fileNameStr.Length() - idx - 1), aExtension);
    }
  }


  return handleExternally;
}

/**
 * Obtains the directory to use.  This tends to vary per platform, and
 * needs to be consistent throughout our codepaths. For platforms where
 * helper apps use the downloads directory, this should be kept in
 * sync with nsDownloadManager.cpp
 *
 * Optionally skip availability of the directory and storage.
 */
static nsresult GetDownloadDirectory(nsIFile **_directory,
                                     bool aSkipChecks = false)
{
  nsCOMPtr<nsIFile> dir;
#ifdef XP_MACOSX
  // On OS X, we first try to get the users download location, if it's set.
  switch (Preferences::GetInt(NS_PREF_DOWNLOAD_FOLDERLIST, -1)) {
    case NS_FOLDER_VALUE_DESKTOP:
      (void) NS_GetSpecialDirectory(NS_OS_DESKTOP_DIR, getter_AddRefs(dir));
      break;
    case NS_FOLDER_VALUE_CUSTOM:
      {
        Preferences::GetComplex(NS_PREF_DOWNLOAD_DIR,
                                NS_GET_IID(nsIFile),
                                getter_AddRefs(dir));
        if (!dir) break;

        // If we're not checking for availability we're done.
        if (aSkipChecks) {
          dir.forget(_directory);
          return NS_OK;
        }

        // We have the directory, and now we need to make sure it exists
        bool dirExists = false;
        (void) dir->Exists(&dirExists);
        if (dirExists) break;

        nsresult rv = dir->Create(nsIFile::DIRECTORY_TYPE, 0755);
        if (NS_FAILED(rv)) {
          dir = nullptr;
          break;
        }
      }
      break;
    case NS_FOLDER_VALUE_DOWNLOADS:
      // This is just the OS default location, so fall out
      break;
  }

  if (!dir) {
    // If not, we default to the OS X default download location.
    nsresult rv = NS_GetSpecialDirectory(NS_OSX_DEFAULT_DOWNLOAD_DIR,
                                         getter_AddRefs(dir));
    NS_ENSURE_SUCCESS(rv, rv);
  }
#else
  // On all other platforms, we default to the systems temporary directory.
  nsresult rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(dir));
  NS_ENSURE_SUCCESS(rv, rv);

#if defined(XP_UNIX)
  // Ensuring that only the current user can read the file names we end up
  // creating. Note that Creating directories with specified permission only
  // supported on Unix platform right now. That's why above if exists.

  uint32_t permissions;
  rv = dir->GetPermissions(&permissions);
  NS_ENSURE_SUCCESS(rv, rv);

  if (permissions != PR_IRWXU) {
    const char* userName = PR_GetEnv("USERNAME");
    if (!userName || !*userName) {
      userName = PR_GetEnv("USER");
    }
    if (!userName || !*userName) {
      userName = PR_GetEnv("LOGNAME");
    }
    if (!userName || !*userName) {
      userName = "mozillaUser";
    }

    nsAutoString userDir;
    userDir.AssignLiteral("mozilla_");
    userDir.AppendASCII(userName);
    userDir.ReplaceChar(FILE_PATH_SEPARATOR FILE_ILLEGAL_CHARACTERS, '_');

    int counter = 0;
    bool pathExists;
    nsCOMPtr<nsIFile> finalPath;

    while (true) {
      nsAutoString countedUserDir(userDir);
      countedUserDir.AppendInt(counter, 10);
      dir->Clone(getter_AddRefs(finalPath));
      finalPath->Append(countedUserDir);

      rv = finalPath->Exists(&pathExists);
      NS_ENSURE_SUCCESS(rv, rv);

      if (pathExists) {
        // If this path has the right permissions, use it.
        rv = finalPath->GetPermissions(&permissions);
        NS_ENSURE_SUCCESS(rv, rv);

        // Ensuring the path is writable by the current user.
        bool isWritable;
        rv = finalPath->IsWritable(&isWritable);
        NS_ENSURE_SUCCESS(rv, rv);

        if (permissions == PR_IRWXU && isWritable) {
          dir = finalPath;
          break;
        }
      }

      rv = finalPath->Create(nsIFile::DIRECTORY_TYPE, PR_IRWXU);
      if (NS_SUCCEEDED(rv)) {
        dir = finalPath;
        break;
      }
      else if (rv != NS_ERROR_FILE_ALREADY_EXISTS) {
        // Unexpected error.
        return rv;
      }

      counter++;
    }
  }

#endif
#endif

  NS_ASSERTION(dir, "Somehow we didn't get a download directory!");
  dir.forget(_directory);
  return NS_OK;
}

/**
 * Structure for storing extension->type mappings.
 * @see defaultMimeEntries
 */
struct nsDefaultMimeTypeEntry {
  const char* mMimeType;
  const char* mFileExtension;
};

/**
 * Default extension->mimetype mappings. These are not overridable.
 * If you add types here, make sure they are lowercase, or you'll regret it.
 */
static const nsDefaultMimeTypeEntry defaultMimeEntries[] =
{
  // The following are those extensions that we're asked about during startup,
  // sorted by order used
  { IMAGE_GIF, "gif" },
  { TEXT_XML, "xml" },
  { APPLICATION_RDF, "rdf" },
  { TEXT_XUL, "xul" },
  { IMAGE_PNG, "png" },
  // -- end extensions used during startup
  { TEXT_CSS, "css" },
  { IMAGE_JPEG, "jpeg" },
  { IMAGE_JPEG, "jpg" },
#ifdef MOZ_JXL
  { IMAGE_JXL, "jxl" },
#endif
  { IMAGE_SVG_XML, "svg" },
  { TEXT_HTML, "html" },
  { TEXT_HTML, "htm" },
  { APPLICATION_XPINSTALL, "xpi" },
  { "application/xhtml+xml", "xhtml" },
  { "application/xhtml+xml", "xht" },
  { TEXT_PLAIN, "txt" },
  { APPLICATION_JSON, "json"},
  { APPLICATION_XJAVASCRIPT, "js"},
  { APPLICATION_XJAVASCRIPT, "jsm"},
  { VIDEO_OGG, "ogv" },
  { VIDEO_OGG, "ogg" },
  { APPLICATION_OGG, "ogg" },
  { AUDIO_OGG, "oga" },
  { AUDIO_OGG, "opus" },
  { APPLICATION_PDF, "pdf" },
  { VIDEO_WEBM, "webm" },
  { AUDIO_WEBM, "webm" },
  { AUDIO_FLAC, "flac" },
#if defined(MOZ_WMF)
  { VIDEO_MP4, "mp4" },
  { AUDIO_MP4, "m4a" },
  { AUDIO_MP3, "mp3" },
#endif
#ifdef MOZ_RAW
  { VIDEO_RAW, "yuv" }
#endif
};

/**
 * This is a small private struct used to help us initialize some
 * default mime types.
 */
struct nsExtraMimeTypeEntry {
  const char* mMimeType; 
  const char* mFileExtensions;
  const char* mDescription;
};

#ifdef XP_MACOSX
#define MAC_TYPE(x) x
#else
#define MAC_TYPE(x) 0
#endif

/**
 * This table lists all of the 'extra' content types that we can deduce from particular
 * file extensions.  These entries also ensure that we provide a good descriptive name
 * when we encounter files with these content types and/or extensions.  These can be
 * overridden by user helper app prefs.
 * If you add types here, make sure they are lowercase, or you'll regret it.
 */
static const nsExtraMimeTypeEntry extraMimeEntries[] =
{
#if defined(XP_MACOSX) // don't define .bin on the mac...use internet config to look that up...
  { APPLICATION_OCTET_STREAM, "exe,com", "Binary File" },
#else
  { APPLICATION_OCTET_STREAM, "exe,com,bin", "Binary File" },
#endif
  { APPLICATION_GZIP2, "gz", "gzip" },
  { "application/x-arj", "arj", "ARJ file" },
  { "application/rtf", "rtf", "Rich Text Format File" },
  { APPLICATION_XPINSTALL, "xpi", "XPInstall Install" },
  { APPLICATION_PDF, "pdf", "Portable Document Format" },
  { APPLICATION_POSTSCRIPT, "ps,eps,ai", "Postscript File" },
  { APPLICATION_XJAVASCRIPT, "js", "Javascript Source File" },
  { APPLICATION_XJAVASCRIPT, "jsm", "Javascript Module Source File" },
  { IMAGE_ART, "art", "ART Image" },
  { IMAGE_BMP, "bmp", "BMP Image" },
  { IMAGE_GIF, "gif", "GIF Image" },
  { IMAGE_ICO, "ico,cur", "ICO Image" },
  { IMAGE_JPEG, "jpeg,jpg,jfif,pjpeg,pjp", "JPEG Image" },
#ifdef MOZ_JXL
  { IMAGE_JXL, "jxl", "JPEG-XL Image" },
#endif
  { IMAGE_PNG, "png", "PNG Image" },
  { IMAGE_APNG, "apng", "APNG Image" },
  { IMAGE_TIFF, "tiff,tif", "TIFF Image" },
  { IMAGE_XBM, "xbm", "XBM Image" },
  { IMAGE_SVG_XML, "svg", "Scalable Vector Graphics" },
  { IMAGE_WEBP, "webp", "WebP Image" },
  { IMAGE_JXL, "jxl", "JPEG XL Image File" },
  { MESSAGE_RFC822, "eml", "RFC-822 data" },
  { TEXT_PLAIN, "txt,text", "Text File" },
  { TEXT_HTML, "html,htm,shtml,ehtml", "HyperText Markup Language" },
  { "application/xhtml+xml", "xhtml,xht", "Extensible HyperText Markup Language" },
  { APPLICATION_MATHML_XML, "mml", "Mathematical Markup Language" },
  { APPLICATION_RDF, "rdf", "Resource Description Framework" },
  { TEXT_XUL, "xul", "XML-Based User Interface Language" },
  { TEXT_XML, "xml,xsl,xbl", "Extensible Markup Language" },
  { TEXT_CSS, "css", "Style Sheet" },
  { TEXT_VCARD, "vcf,vcard", "Contact Information" },
  { VIDEO_OGG, "ogv", "Ogg Video" },
  { VIDEO_OGG, "ogg", "Ogg Video" },
  { APPLICATION_OGG, "ogg", "Ogg Video"},
  { AUDIO_OGG, "oga", "Ogg Audio" },
  { AUDIO_OGG, "opus", "Opus Audio" },
  { VIDEO_WEBM, "webm", "Web Media Video" },
  { AUDIO_WEBM, "webm", "Web Media Audio" },
  { AUDIO_MP3, "mp3", "MPEG Audio" },
  { VIDEO_MP4, "mp4", "MPEG-4 Video" },
  { AUDIO_MP4, "m4a", "MPEG-4 Audio" },
  { VIDEO_RAW, "yuv", "Raw YUV Video" },
  { AUDIO_WAV, "wav", "Waveform Audio" },
  { VIDEO_3GPP, "3gpp,3gp", "3GPP Video" },
  { VIDEO_3GPP2,"3g2", "3GPP2 Video" },
  { AUDIO_MIDI, "mid", "Standard MIDI Audio" }
};

#undef MAC_TYPE

/**
 * File extensions for which decoding should be disabled.
 * NOTE: These MUST be lower-case and ASCII.
 */
static const nsDefaultMimeTypeEntry nonDecodableExtensions[] = {
  { APPLICATION_GZIP, "gz" }, 
  { APPLICATION_GZIP, "tgz" },
  { APPLICATION_ZIP, "zip" },
  { APPLICATION_COMPRESS, "z" },
  { APPLICATION_GZIP, "svgz" }
};

NS_IMPL_ISUPPORTS(
  nsExternalHelperAppService,
  nsIExternalHelperAppService,
  nsPIExternalAppLauncher,
  nsIExternalProtocolService,
  nsIMIMEService,
  nsIObserver,
  nsISupportsWeakReference)

nsExternalHelperAppService::nsExternalHelperAppService()
{
}
nsresult nsExternalHelperAppService::Init()
{
  // Add an observer for profile change
  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
  if (!obs)
    return NS_ERROR_FAILURE;

  nsresult rv = obs->AddObserver(this, "profile-before-change", true);
  NS_ENSURE_SUCCESS(rv, rv);
  return obs->AddObserver(this, "last-pb-context-exited", true);
}

nsExternalHelperAppService::~nsExternalHelperAppService()
{
}


nsresult
nsExternalHelperAppService::DoContentContentProcessHelper(const nsACString& aMimeContentType,
                                                          nsIRequest *aRequest,
                                                          nsIInterfaceRequestor *aContentContext,
                                                          bool aForceSave,
                                                          nsIInterfaceRequestor *aWindowContext,
                                                          nsIStreamListener ** aStreamListener)
{
  nsCOMPtr<nsPIDOMWindowOuter> window = do_GetInterface(aContentContext);
  NS_ENSURE_STATE(window);

  // We need to get a hold of a ContentChild so that we can begin forwarding
  // this data to the parent.  In the HTTP case, this is unfortunate, since
  // we're actually passing data from parent->child->parent wastefully, but
  // the Right Fix will eventually be to short-circuit those channels on the
  // parent side based on some sort of subscription concept.
  using mozilla::dom::ContentChild;
  using mozilla::dom::ExternalHelperAppChild;
  ContentChild *child = ContentChild::GetSingleton();
  if (!child) {
    return NS_ERROR_FAILURE;
  }

  nsCString disp;
  nsCOMPtr<nsIURI> uri;
  int64_t contentLength = -1;
  bool wasFileChannel = false;
  uint32_t contentDisposition = -1;
  nsAutoString fileName;

  nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
  if (channel) {
    channel->GetURI(getter_AddRefs(uri));
    channel->GetContentLength(&contentLength);
    channel->GetContentDisposition(&contentDisposition);
    channel->GetContentDispositionFilename(fileName);
    channel->GetContentDispositionHeader(disp);

    nsCOMPtr<nsIFileChannel> fileChan(do_QueryInterface(aRequest));
    wasFileChannel = fileChan != nullptr;
  }


  nsCOMPtr<nsIURI> referrer;
  NS_GetReferrerFromChannel(channel, getter_AddRefs(referrer));

  OptionalURIParams uriParams, referrerParams;
  SerializeURI(uri, uriParams);
  SerializeURI(referrer, referrerParams);

  // Now we build a protocol for forwarding our data to the parent.  The
  // protocol will act as a listener on the child-side and create a "real"
  // helperAppService listener on the parent-side, via another call to
  // DoContent.
  mozilla::dom::PExternalHelperAppChild *pc =
    child->SendPExternalHelperAppConstructor(uriParams,
                                              nsCString(aMimeContentType),
                                              disp, contentDisposition,
                                              fileName, aForceSave,
                                              contentLength, wasFileChannel,
                                              referrerParams,
                                              mozilla::dom::TabChild::GetFrom(window));
  ExternalHelperAppChild *childListener = static_cast<ExternalHelperAppChild *>(pc);

  NS_ADDREF(*aStreamListener = childListener);

  uint32_t reason = nsIHelperAppLauncherDialog::REASON_CANTHANDLE;

  RefPtr<nsExternalAppHandler> handler =
    new nsExternalAppHandler(nullptr, EmptyCString(), aContentContext, aWindowContext, this,
                             fileName, reason, aForceSave);
  if (!handler) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  childListener->SetHandler(handler);
  return NS_OK;
}

NS_IMETHODIMP nsExternalHelperAppService::DoContent(const nsACString& aMimeContentType,
                                                    nsIRequest *aRequest,
                                                    nsIInterfaceRequestor *aContentContext,
                                                    bool aForceSave,
                                                    nsIInterfaceRequestor *aWindowContext,
                                                    nsIStreamListener ** aStreamListener)
{
  if (XRE_IsContentProcess()) {
    return DoContentContentProcessHelper(aMimeContentType, aRequest, aContentContext,
                                         aForceSave, aWindowContext, aStreamListener);
  }

  nsAutoString fileName;
  nsAutoCString fileExtension;
  uint32_t reason = nsIHelperAppLauncherDialog::REASON_CANTHANDLE;
  uint32_t contentDisposition = -1;

  // Get the file extension and name that we will need later
  nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
  nsCOMPtr<nsIURI> uri;
  int64_t contentLength = -1;
  if (channel) {
    channel->GetURI(getter_AddRefs(uri));
    channel->GetContentLength(&contentLength);
    channel->GetContentDisposition(&contentDisposition);
    channel->GetContentDispositionFilename(fileName);

    // Check if we have a POST request, in which case we don't want to use
    // the url's extension
    bool allowURLExt = true;
    nsCOMPtr<nsIHttpChannel> httpChan = do_QueryInterface(channel);
    if (httpChan) {
      nsAutoCString requestMethod;
      httpChan->GetRequestMethod(requestMethod);
      allowURLExt = !requestMethod.EqualsLiteral("POST");
    }

    // Check if we had a query string - we don't want to check the URL
    // extension if a query is present in the URI
    // If we already know we don't want to check the URL extension, don't
    // bother checking the query
    if (uri && allowURLExt) {
      nsCOMPtr<nsIURL> url = do_QueryInterface(uri);

      if (url) {
        nsAutoCString query;

        // We only care about the query for HTTP and HTTPS URLs
        nsresult rv;
        bool isHTTP, isHTTPS;
        rv = uri->SchemeIs("http", &isHTTP);
        if (NS_FAILED(rv)) {
          isHTTP = false;
        }
        rv = uri->SchemeIs("https", &isHTTPS);
        if (NS_FAILED(rv)) {
          isHTTPS = false;
        }
        if (isHTTP || isHTTPS) {
          url->GetQuery(query);
        }

        // Only get the extension if the query is empty; if it isn't, then the
        // extension likely belongs to a cgi script and isn't helpful
        allowURLExt = query.IsEmpty();
      }
    }
    // Extract name & extension
    bool isAttachment = GetFilenameAndExtensionFromChannel(channel, fileName,
                                                             fileExtension,
                                                             allowURLExt);
    LOG(("Found extension '%s' (filename is '%s', handling attachment: %i)",
         fileExtension.get(), NS_ConvertUTF16toUTF8(fileName).get(),
         isAttachment));
    if (isAttachment) {
      reason = nsIHelperAppLauncherDialog::REASON_SERVERREQUEST;
    }
  }

  LOG(("HelperAppService::DoContent: mime '%s', extension '%s'\n",
       PromiseFlatCString(aMimeContentType).get(), fileExtension.get()));

  // We get the mime service here even though we're the default implementation
  // of it, so it's possible to override only the mime service and not need to
  // reimplement the whole external helper app service itself.
  nsCOMPtr<nsIMIMEService> mimeSvc(do_GetService(NS_MIMESERVICE_CONTRACTID));
  NS_ENSURE_TRUE(mimeSvc, NS_ERROR_FAILURE);

  // Try to find a mime object by looking at the mime type/extension
  nsCOMPtr<nsIMIMEInfo> mimeInfo;
  if (aMimeContentType.Equals(APPLICATION_GUESS_FROM_EXT, nsCaseInsensitiveCStringComparator())) {
    nsAutoCString mimeType;
    if (!fileExtension.IsEmpty()) {
      mimeSvc->GetFromTypeAndExtension(EmptyCString(), fileExtension, getter_AddRefs(mimeInfo));
      if (mimeInfo) {
        mimeInfo->GetMIMEType(mimeType);

        LOG(("OS-Provided mime type '%s' for extension '%s'\n", 
             mimeType.get(), fileExtension.get()));
      }
    }

    if (fileExtension.IsEmpty() || mimeType.IsEmpty()) {
      // Extension lookup gave us no useful match
      mimeSvc->GetFromTypeAndExtension(NS_LITERAL_CSTRING(APPLICATION_OCTET_STREAM), fileExtension,
                                       getter_AddRefs(mimeInfo));
      mimeType.AssignLiteral(APPLICATION_OCTET_STREAM);
    }

    if (channel) {
      channel->SetContentType(mimeType);
    }

    // Don't overwrite SERVERREQUEST
    if (reason == nsIHelperAppLauncherDialog::REASON_CANTHANDLE) {
      reason = nsIHelperAppLauncherDialog::REASON_TYPESNIFFED;
    }
  } else {
    mimeSvc->GetFromTypeAndExtension(aMimeContentType, fileExtension,
                                     getter_AddRefs(mimeInfo));
  } 
  LOG(("Type/Ext lookup found 0x%p\n", mimeInfo.get()));

  // No mimeinfo -> we can't continue. probably OOM.
  if (!mimeInfo) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  *aStreamListener = nullptr;
  // We want the mimeInfo's primary extension to pass it to
  // nsExternalAppHandler
  nsAutoCString buf;
  mimeInfo->GetPrimaryExtension(buf);

  nsExternalAppHandler * handler = new nsExternalAppHandler(mimeInfo,
                                                            buf,
                                                            aContentContext,
                                                            aWindowContext,
                                                            this,
                                                            fileName,
                                                            reason,
                                                            aForceSave);
  if (!handler) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  NS_ADDREF(*aStreamListener = handler);
  return NS_OK;
}

NS_IMETHODIMP nsExternalHelperAppService::ApplyDecodingForExtension(const nsACString& aExtension,
                                                                    const nsACString& aEncodingType,
                                                                    bool *aApplyDecoding)
{
  *aApplyDecoding = true;
  uint32_t i;
  for(i = 0; i < ArrayLength(nonDecodableExtensions); ++i) {
    if (aExtension.LowerCaseEqualsASCII(nonDecodableExtensions[i].mFileExtension) &&
        aEncodingType.LowerCaseEqualsASCII(nonDecodableExtensions[i].mMimeType)) {
      *aApplyDecoding = false;
      break;
    }
  }
  return NS_OK;
}

nsresult nsExternalHelperAppService::GetFileTokenForPath(const char16_t * aPlatformAppPath,
                                                         nsIFile ** aFile)
{
  nsDependentString platformAppPath(aPlatformAppPath);
  // First, check if we have an absolute path
  nsIFile* localFile = nullptr;
  nsresult rv = NS_NewLocalFile(platformAppPath, true, &localFile);
  if (NS_SUCCEEDED(rv)) {
    *aFile = localFile;
    bool exists;
    if (NS_FAILED((*aFile)->Exists(&exists)) || !exists) {
      NS_RELEASE(*aFile);
      return NS_ERROR_FILE_NOT_FOUND;
    }
    return NS_OK;
  }


  // Second, check if file exists in mozilla program directory
  rv = NS_GetSpecialDirectory(NS_XPCOM_CURRENT_PROCESS_DIR, aFile);
  if (NS_SUCCEEDED(rv)) {
    rv = (*aFile)->Append(platformAppPath);
    if (NS_SUCCEEDED(rv)) {
      bool exists = false;
      rv = (*aFile)->Exists(&exists);
      if (NS_SUCCEEDED(rv) && exists)
        return NS_OK;
    }
    NS_RELEASE(*aFile);
  }


  return NS_ERROR_NOT_AVAILABLE;
}

//////////////////////////////////////////////////////////////////////////////////////////////////////
// begin external protocol service default implementation...
//////////////////////////////////////////////////////////////////////////////////////////////////////
NS_IMETHODIMP nsExternalHelperAppService::ExternalProtocolHandlerExists(const char * aProtocolScheme,
                                                                        bool * aHandlerExists)
{
  nsCOMPtr<nsIHandlerInfo> handlerInfo;
  nsresult rv = GetProtocolHandlerInfo(nsDependentCString(aProtocolScheme), 
                                       getter_AddRefs(handlerInfo));
  NS_ENSURE_SUCCESS(rv, rv);

  // See if we have any known possible handler apps for this
  nsCOMPtr<nsIMutableArray> possibleHandlers;
  handlerInfo->GetPossibleApplicationHandlers(getter_AddRefs(possibleHandlers));

  uint32_t length;
  possibleHandlers->GetLength(&length);
  if (length) {
    *aHandlerExists = true;
    return NS_OK;
  }

  // if not, fall back on an os-based handler
  return OSProtocolHandlerExists(aProtocolScheme, aHandlerExists);
}

NS_IMETHODIMP nsExternalHelperAppService::IsExposedProtocol(const char * aProtocolScheme, bool * aResult)
{
  // check the per protocol setting first.  it always takes precedence.
  // if not set, then use the global setting.

  nsAutoCString prefName("network.protocol-handler.expose.");
  prefName += aProtocolScheme;
  bool val;
  if (NS_SUCCEEDED(Preferences::GetBool(prefName.get(), &val))) {
    *aResult = val;
    return NS_OK;
  }

  // by default, no protocol is exposed.  i.e., by default all link clicks must
  // go through the external protocol service.  most applications override this
  // default behavior.
  *aResult =
    Preferences::GetBool("network.protocol-handler.expose-all", false);

  return NS_OK;
}

NS_IMETHODIMP nsExternalHelperAppService::LoadUrl(nsIURI * aURL)
{
  return LoadURI(aURL, nullptr);
}

static const char kExternalProtocolPrefPrefix[]  = "network.protocol-handler.external.";
static const char kExternalProtocolDefaultPref[] = "network.protocol-handler.external-default";

// static
nsresult nsExternalHelperAppService::EscapeURI(nsIURI* aURI, nsIURI** aResult) {
  MOZ_ASSERT(aURI);
  MOZ_ASSERT(aResult);

  nsAutoCString spec;
  aURI->GetSpec(spec);

  if (spec.Find("%00") != -1) return NS_ERROR_MALFORMED_URI;

  nsAutoCString escapedSpec;
  nsresult rv = NS_EscapeURL(spec, esc_AlwaysCopy | esc_ExtHandler, escapedSpec,
                             fallible);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIIOService> ios(do_GetIOService());
  return ios->NewURI(escapedSpec, nullptr, nullptr, aResult);
}

NS_IMETHODIMP 
nsExternalHelperAppService::LoadURI(nsIURI *aURI,
                                    nsIInterfaceRequestor *aWindowContext)
{
  NS_ENSURE_ARG_POINTER(aURI);

  if (XRE_IsContentProcess()) {
    URIParams uri;
    SerializeURI(aURI, uri);

    nsCOMPtr<nsITabChild> tabChild(do_GetInterface(aWindowContext));
    mozilla::dom::ContentChild::GetSingleton()->
      SendLoadURIExternal(uri, static_cast<dom::TabChild*>(tabChild.get()));
    return NS_OK;
  }

  nsCOMPtr<nsIURI> escapedURI;
  nsresult rv = EscapeURI(aURI, getter_AddRefs(escapedURI));
  NS_ENSURE_SUCCESS(rv, rv);

  nsAutoCString scheme;
  escapedURI->GetScheme(scheme);
  if (scheme.IsEmpty())
    return NS_OK; // must have a scheme

  // Deny load if the prefs say to do so
  nsAutoCString externalPref(kExternalProtocolPrefPrefix);
  externalPref += scheme;
  bool allowLoad  = false;
  if (NS_FAILED(Preferences::GetBool(externalPref.get(), &allowLoad))) {
    // no scheme-specific value, check the default
    if (NS_FAILED(Preferences::GetBool(kExternalProtocolDefaultPref,
                                       &allowLoad))) {
      return NS_OK; // missing default pref
    }
  }

  if (!allowLoad) {
    return NS_OK; // explicitly denied
  }

  nsCOMPtr<nsIHandlerInfo> handler;
  rv = GetProtocolHandlerInfo(scheme, getter_AddRefs(handler));
  NS_ENSURE_SUCCESS(rv, rv);

  nsHandlerInfoAction preferredAction;
  handler->GetPreferredAction(&preferredAction);
  bool alwaysAsk = true;
  handler->GetAlwaysAskBeforeHandling(&alwaysAsk);

  // if we are not supposed to ask, and the preferred action is to use
  // a helper app or the system default, we just launch the URI.
  if (!alwaysAsk && (preferredAction == nsIHandlerInfo::useHelperApp ||
                     preferredAction == nsIHandlerInfo::useSystemDefault))
    return handler->LaunchWithURI(escapedURI, aWindowContext);
  
  nsCOMPtr<nsIContentDispatchChooser> chooser =
    do_CreateInstance("@mozilla.org/content-dispatch-chooser;1", &rv);
  NS_ENSURE_SUCCESS(rv, rv);
  
  return chooser->Ask(handler, aWindowContext, escapedURI,
                      nsIContentDispatchChooser::REASON_CANNOT_HANDLE);
}

NS_IMETHODIMP nsExternalHelperAppService::GetApplicationDescription(const nsACString& aScheme, nsAString& _retval)
{
  // this method should only be implemented by each OS specific implementation of this service.
  return NS_ERROR_NOT_IMPLEMENTED;
}


//////////////////////////////////////////////////////////////////////////////////////////////////////
// Methods related to deleting temporary files on exit
//////////////////////////////////////////////////////////////////////////////////////////////////////

/* static */
nsresult
nsExternalHelperAppService::DeleteTemporaryFileHelper(nsIFile * aTemporaryFile,
                                                      nsCOMArray<nsIFile> &aFileList)
{
  bool isFile = false;

  // as a safety measure, make sure the nsIFile is really a file and not a directory object.
  aTemporaryFile->IsFile(&isFile);
  if (!isFile) return NS_OK;

  aFileList.AppendObject(aTemporaryFile);

  return NS_OK;
}

NS_IMETHODIMP
nsExternalHelperAppService::DeleteTemporaryFileOnExit(nsIFile* aTemporaryFile)
{
  return DeleteTemporaryFileHelper(aTemporaryFile, mTemporaryFilesList);
}

NS_IMETHODIMP
nsExternalHelperAppService::DeleteTemporaryPrivateFileWhenPossible(nsIFile* aTemporaryFile)
{
  return DeleteTemporaryFileHelper(aTemporaryFile, mTemporaryPrivateFilesList);
}

void nsExternalHelperAppService::ExpungeTemporaryFilesHelper(nsCOMArray<nsIFile> &fileList)
{
  int32_t numEntries = fileList.Count();
  nsIFile* localFile;
  for (int32_t index = 0; index < numEntries; index++)
  {
    localFile = fileList[index];
    if (localFile) {
      // First make the file writable, since the temp file is probably readonly.
      localFile->SetPermissions(0600);
      localFile->Remove(false);
    }
  }

  fileList.Clear();
}

void nsExternalHelperAppService::ExpungeTemporaryFiles()
{
  ExpungeTemporaryFilesHelper(mTemporaryFilesList);
}

void nsExternalHelperAppService::ExpungeTemporaryPrivateFiles()
{
  ExpungeTemporaryFilesHelper(mTemporaryPrivateFilesList);
}

static const char kExternalWarningPrefPrefix[] = 
  "network.protocol-handler.warn-external.";
static const char kExternalWarningDefaultPref[] = 
  "network.protocol-handler.warn-external-default";

NS_IMETHODIMP
nsExternalHelperAppService::GetProtocolHandlerInfo(const nsACString &aScheme,
                                                   nsIHandlerInfo **aHandlerInfo)
{
  // XXX enterprise customers should be able to turn this support off with a
  // single master pref (maybe use one of the "exposed" prefs here?)

  bool exists;
  nsresult rv = GetProtocolHandlerInfoFromOS(aScheme, &exists, aHandlerInfo);
  if (NS_FAILED(rv)) {
    // Either it knows nothing, or we ran out of memory
    return NS_ERROR_FAILURE;
  }
  
  nsCOMPtr<nsIHandlerService> handlerSvc = do_GetService(NS_HANDLERSERVICE_CONTRACTID);
  if (handlerSvc) {
    bool hasHandler = false;
    (void) handlerSvc->Exists(*aHandlerInfo, &hasHandler);
    if (hasHandler) {
      rv = handlerSvc->FillHandlerInfo(*aHandlerInfo, EmptyCString());
      if (NS_SUCCEEDED(rv))
        return NS_OK;
    }
  }
  
  return SetProtocolHandlerDefaults(*aHandlerInfo, exists);
}

NS_IMETHODIMP
nsExternalHelperAppService::GetProtocolHandlerInfoFromOS(const nsACString &aScheme,
                                                         bool *found,
                                                         nsIHandlerInfo **aHandlerInfo)
{
  // intended to be implemented by the subclass
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsExternalHelperAppService::SetProtocolHandlerDefaults(nsIHandlerInfo *aHandlerInfo,
                                                       bool aOSHandlerExists)
{
  // this type isn't in our database, so we've only got an OS default handler,
  // if one exists

  if (aOSHandlerExists) {
    // we've got a default, so use it
    aHandlerInfo->SetPreferredAction(nsIHandlerInfo::useSystemDefault);

    // whether or not to ask the user depends on the warning preference
    nsAutoCString scheme;
    aHandlerInfo->GetType(scheme);
    
    nsAutoCString warningPref(kExternalWarningPrefPrefix);
    warningPref += scheme;
    bool warn;
    if (NS_FAILED(Preferences::GetBool(warningPref.get(), &warn))) {
      // no scheme-specific value, check the default
      warn = Preferences::GetBool(kExternalWarningDefaultPref, true);
    }
    aHandlerInfo->SetAlwaysAskBeforeHandling(warn);
  } else {
    // If no OS default existed, we set the preferred action to alwaysAsk. 
    // This really means not initialized (i.e. there's no available handler)
    // to all the code...
    aHandlerInfo->SetPreferredAction(nsIHandlerInfo::alwaysAsk);
  }

  return NS_OK;
}
 
// XPCOM profile change observer
NS_IMETHODIMP
nsExternalHelperAppService::Observe(nsISupports *aSubject, const char *aTopic, const char16_t *someData )
{
  if (!strcmp(aTopic, "profile-before-change")) {
    ExpungeTemporaryFiles();
  } else if (!strcmp(aTopic, "last-pb-context-exited")) {
    ExpungeTemporaryPrivateFiles();
  }
  return NS_OK;
}

//////////////////////////////////////////////////////////////////////////////////////////////////////
// begin external app handler implementation 
//////////////////////////////////////////////////////////////////////////////////////////////////////

NS_IMPL_ADDREF(nsExternalAppHandler)
NS_IMPL_RELEASE(nsExternalAppHandler)

NS_INTERFACE_MAP_BEGIN(nsExternalAppHandler)
   NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIStreamListener)
   NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
   NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
   NS_INTERFACE_MAP_ENTRY(nsIHelperAppLauncher)
   NS_INTERFACE_MAP_ENTRY(nsICancelable)
   NS_INTERFACE_MAP_ENTRY(nsITimerCallback)
   NS_INTERFACE_MAP_ENTRY(nsIBackgroundFileSaverObserver)
NS_INTERFACE_MAP_END_THREADSAFE

nsExternalAppHandler::nsExternalAppHandler(nsIMIMEInfo * aMIMEInfo,
                                           const nsCSubstring& aTempFileExtension,
                                           nsIInterfaceRequestor* aContentContext,
                                           nsIInterfaceRequestor* aWindowContext,
                                           nsExternalHelperAppService *aExtProtSvc,
                                           const nsAString& aSuggestedFilename,
                                           uint32_t aReason, bool aForceSave)
: mMimeInfo(aMIMEInfo)
, mContentContext(aContentContext)
, mWindowContext(aWindowContext)
, mWindowToClose(nullptr)
, mSuggestedFileName(aSuggestedFilename)
, mForceSave(aForceSave)
, mCanceled(false)
, mShouldCloseWindow(false)
, mStopRequestIssued(false)
, mReason(aReason)
, mContentLength(-1)
, mProgress(0)
, mSaver(nullptr)
, mDialogProgressListener(nullptr)
, mTransfer(nullptr)
, mRequest(nullptr)
, mExtProtSvc(aExtProtSvc)
{

  // make sure the extention includes the '.'
  if (!aTempFileExtension.IsEmpty() && aTempFileExtension.First() != '.')
    mTempFileExtension = char16_t('.');
  AppendUTF8toUTF16(aTempFileExtension, mTempFileExtension);

  // Replace platform specific path separator and illegal characters to avoid any confusion
  mSuggestedFileName.ReplaceChar(KNOWN_PATH_SEPARATORS, '_');
  mSuggestedFileName.ReplaceChar(FILE_ILLEGAL_CHARACTERS, ' ');
  mSuggestedFileName.ReplaceChar(char16_t(0), '_');
  mTempFileExtension.ReplaceChar(KNOWN_PATH_SEPARATORS, '_');
  mTempFileExtension.ReplaceChar(FILE_ILLEGAL_CHARACTERS, ' ');

  // Remove unsafe bidi characters which might have spoofing implications (bug 511521).
  const char16_t unsafeBidiCharacters[] = {
    char16_t(0x061c), // Arabic Letter Mark
    char16_t(0x200e), // Left-to-Right Mark
    char16_t(0x200f), // Right-to-Left Mark
    char16_t(0x202a), // Left-to-Right Embedding
    char16_t(0x202b), // Right-to-Left Embedding
    char16_t(0x202c), // Pop Directional Formatting
    char16_t(0x202d), // Left-to-Right Override
    char16_t(0x202e), // Right-to-Left Override
    char16_t(0x2066), // Left-to-Right Isolate
    char16_t(0x2067), // Right-to-Left Isolate
    char16_t(0x2068), // First Strong Isolate
    char16_t(0x2069), // Pop Directional Isolate
    char16_t(0)
  };
  mSuggestedFileName.ReplaceChar(unsafeBidiCharacters, '_');
  mTempFileExtension.ReplaceChar(unsafeBidiCharacters, '_');

  // Make sure extension is correct.
  EnsureSuggestedFileName();

  mBufferSize = Preferences::GetUint("network.buffer.cache.size", 4096);
}

nsExternalAppHandler::~nsExternalAppHandler()
{
  MOZ_ASSERT(!mSaver, "Saver should hold a reference to us until deleted");
}

void
nsExternalAppHandler::DidDivertRequest(nsIRequest *request)
{
  MOZ_ASSERT(XRE_IsContentProcess(), "in child process");
  // Remove our request from the child loadGroup
  RetargetLoadNotifications(request);
  MaybeCloseWindow();
}

NS_IMETHODIMP nsExternalAppHandler::SetWebProgressListener(nsIWebProgressListener2 * aWebProgressListener)
{
  // This is always called by nsHelperDlg.js. Go ahead and register the
  // progress listener. At this point, we don't have mTransfer.
  mDialogProgressListener = aWebProgressListener;
  return NS_OK;
}

NS_IMETHODIMP nsExternalAppHandler::GetTargetFile(nsIFile** aTarget)
{
  if (mFinalFileDestination)
    *aTarget = mFinalFileDestination;
  else
    *aTarget = mTempFile;

  NS_IF_ADDREF(*aTarget);
  return NS_OK;
}

NS_IMETHODIMP nsExternalAppHandler::GetTargetFileIsExecutable(bool *aExec)
{
  // Use the real target if it's been set
  if (mFinalFileDestination)
    return mFinalFileDestination->IsExecutable(aExec);

  // Otherwise, use the stored executable-ness of the temporary
  *aExec = mTempFileIsExecutable;
  return NS_OK;
}

NS_IMETHODIMP nsExternalAppHandler::GetTimeDownloadStarted(PRTime* aTime)
{
  *aTime = mTimeDownloadStarted;
  return NS_OK;
}

NS_IMETHODIMP nsExternalAppHandler::GetContentLength(int64_t *aContentLength)
{
  *aContentLength = mContentLength;
  return NS_OK;
}

void nsExternalAppHandler::RetargetLoadNotifications(nsIRequest *request)
{
  // we are going to run the downloading of the helper app in our own little docloader / load group context. 
  // so go ahead and force the creation of a load group and doc loader for us to use...
  nsCOMPtr<nsIChannel> aChannel = do_QueryInterface(request);
  if (!aChannel)
    return;

  // we need to store off the original (pre redirect!) channel that initiated the load. We do
  // this so later on, we can pass any refresh urls associated with the original channel back to the 
  // window context which started the whole process. More comments about that are listed below....
  // HACK ALERT: it's pretty bogus that we are getting the document channel from the doc loader. 
  // ideally we should be able to just use mChannel (the channel we are extracting content from) or
  // the default load channel associated with the original load group. Unfortunately because
  // a redirect may have occurred, the doc loader is the only one with a ptr to the original channel 
  // which is what we really want....

  // Note that we need to do this before removing aChannel from the loadgroup,
  // since that would mess with the original channel on the loader.
  nsCOMPtr<nsIDocumentLoader> origContextLoader =
    do_GetInterface(mContentContext);
  if (origContextLoader) {
    origContextLoader->GetDocumentChannel(getter_AddRefs(mOriginalChannel));
  }

  bool isPrivate = NS_UsePrivateBrowsing(aChannel);

  nsCOMPtr<nsILoadGroup> oldLoadGroup;
  aChannel->GetLoadGroup(getter_AddRefs(oldLoadGroup));

  if(oldLoadGroup) {
    oldLoadGroup->RemoveRequest(request, nullptr, NS_BINDING_RETARGETED);
  }
      
  aChannel->SetLoadGroup(nullptr);
  aChannel->SetNotificationCallbacks(nullptr);

  nsCOMPtr<nsIPrivateBrowsingChannel> pbChannel = do_QueryInterface(aChannel);
  if (pbChannel) {
    pbChannel->SetPrivate(isPrivate);
  }
}

/**
 * Make mTempFileExtension contain an extension exactly when its previous value
 * is different from mSuggestedFileName's extension, so that it can be appended
 * to mSuggestedFileName and form a valid, useful leaf name.
 * This is required so that the (renamed) temporary file has the correct extension
 * after downloading to make sure the OS will launch the application corresponding
 * to the MIME type (which was used to calculate mTempFileExtension).  This prevents
 * a cgi-script named foobar.exe that returns application/zip from being named
 * foobar.exe and executed as an executable file. It also blocks content that
 * a web site might provide with a content-disposition header indicating
 * filename="foobar.exe" from being downloaded to a file with extension .exe
 * and executed.
 */
void nsExternalAppHandler::EnsureSuggestedFileName()
{
  // Make sure there is a mTempFileExtension (not "" or ".").
  // Remember that mTempFileExtension will always have the leading "."
  // (the check for empty is just to be safe).
  if (mTempFileExtension.Length() > 1)
  {
    // Get mSuggestedFileName's current extension.
    nsAutoString fileExt;
    int32_t pos = mSuggestedFileName.RFindChar('.');
    if (pos != kNotFound)
      mSuggestedFileName.Right(fileExt, mSuggestedFileName.Length() - pos);

    // Now, compare fileExt to mTempFileExtension.
    if (fileExt.Equals(mTempFileExtension, nsCaseInsensitiveStringComparator()))
    {
      // Matches -> mTempFileExtension can be empty
      mTempFileExtension.Truncate();
    }
  }
}

nsresult nsExternalAppHandler::SetUpTempFile(nsIChannel * aChannel)
{
  // First we need to try to get the destination directory for the temporary
  // file.
  nsresult rv = GetDownloadDirectory(getter_AddRefs(mTempFile));
  NS_ENSURE_SUCCESS(rv, rv);

  // At this point, we do not have a filename for the temp file.  For security
  // purposes, this cannot be predictable, so we must use a cryptographic
  // quality PRNG to generate one.
  // We will request raw random bytes, and transform that to a base64 string,
  // as all characters from the base64 set are acceptable for filenames.  For
  // each three bytes of random data, we will get four bytes of ASCII.  Request
  // a bit more, to be safe, and truncate to the length we want in the end.

  const uint32_t wantedFileNameLength = 8;
  const uint32_t requiredBytesLength =
    static_cast<uint32_t>((wantedFileNameLength + 1) / 4 * 3);

  nsCOMPtr<nsIRandomGenerator> rg =
    do_GetService("@mozilla.org/security/random-generator;1", &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  uint8_t *buffer;
  rv = rg->GenerateRandomBytes(requiredBytesLength, &buffer);
  NS_ENSURE_SUCCESS(rv, rv);

  nsAutoCString tempLeafName;
  nsDependentCSubstring randomData(reinterpret_cast<const char*>(buffer), requiredBytesLength);
  rv = Base64Encode(randomData, tempLeafName);
  free(buffer);
  buffer = nullptr;
  NS_ENSURE_SUCCESS(rv, rv);

  tempLeafName.Truncate(wantedFileNameLength);

  // Base64 characters are alphanumeric (a-zA-Z0-9) and '+' and '/', so we need
  // to replace illegal characters -- notably '/'
  tempLeafName.ReplaceChar(KNOWN_PATH_SEPARATORS FILE_ILLEGAL_CHARACTERS, '_');

  // now append our extension.
  nsAutoCString ext;
  mMimeInfo->GetPrimaryExtension(ext);
  if (!ext.IsEmpty()) {
    ext.ReplaceChar(KNOWN_PATH_SEPARATORS FILE_ILLEGAL_CHARACTERS, '_');
    if (ext.First() != '.')
      tempLeafName.Append('.');
    tempLeafName.Append(ext);
  }

  // We need to temporarily create a dummy file with the correct
  // file extension to determine the executable-ness, so do this before adding
  // the extra .part extension.
  nsCOMPtr<nsIFile> dummyFile;
  rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(dummyFile));
  NS_ENSURE_SUCCESS(rv, rv);

  // Set the file name without .part
  rv = dummyFile->Append(NS_ConvertUTF8toUTF16(tempLeafName));
  NS_ENSURE_SUCCESS(rv, rv);
  rv = dummyFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);
  NS_ENSURE_SUCCESS(rv, rv);

  // Store executable-ness then delete
  dummyFile->IsExecutable(&mTempFileIsExecutable);
  dummyFile->Remove(false);

  // Add an additional .part to prevent the OS from running this file in the
  // default application.
  tempLeafName.AppendLiteral(".part");

  rv = mTempFile->Append(NS_ConvertUTF8toUTF16(tempLeafName));
  // make this file unique!!!
  NS_ENSURE_SUCCESS(rv, rv);
  rv = mTempFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);
  NS_ENSURE_SUCCESS(rv, rv);

  // Now save the temp leaf name, minus the ".part" bit, so we can use it later.
  // This is a bit broken in the case when createUnique actually had to append
  // some numbers, because then we now have a filename like foo.bar-1.part and
  // we'll end up with foo.bar-1.bar as our final filename if we end up using
  // this.  But the other options are all bad too....  Ideally we'd have a way
  // to tell createUnique to put its unique marker before the extension that
  // comes before ".part" or something.
  rv = mTempFile->GetLeafName(mTempLeafName);
  NS_ENSURE_SUCCESS(rv, rv);

  NS_ENSURE_TRUE(StringEndsWith(mTempLeafName, NS_LITERAL_STRING(".part")),
                 NS_ERROR_UNEXPECTED);

  // Strip off the ".part" from mTempLeafName
  mTempLeafName.Truncate(mTempLeafName.Length() - ArrayLength(".part") + 1);

  MOZ_ASSERT(!mSaver, "Output file initialization called more than once!");
  mSaver = do_CreateInstance(NS_BACKGROUNDFILESAVERSTREAMLISTENER_CONTRACTID,
                             &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = mSaver->SetObserver(this);
  if (NS_FAILED(rv)) {
    mSaver = nullptr;
    return rv;
  }

  rv = mSaver->EnableSha256();
  NS_ENSURE_SUCCESS(rv, rv);

  rv = mSaver->EnableSignatureInfo();
  NS_ENSURE_SUCCESS(rv, rv);
  LOG(("Enabled hashing and signature verification"));

  rv = mSaver->SetTarget(mTempFile, false);
  NS_ENSURE_SUCCESS(rv, rv);

  return rv;
}

void
nsExternalAppHandler::MaybeApplyDecodingForExtension(nsIRequest *aRequest)
{
  MOZ_ASSERT(aRequest);

  nsCOMPtr<nsIEncodedChannel> encChannel = do_QueryInterface(aRequest);
  if (!encChannel) {
    return;
  }

  // Turn off content encoding conversions if needed
  bool applyConversion = true;

  // First, check to see if conversion is already disabled.  If so, we
  // have nothing to do here.
  encChannel->GetApplyConversion(&applyConversion);
  if (!applyConversion) {
    return;
  }

  nsCOMPtr<nsIURL> sourceURL(do_QueryInterface(mSourceUrl));
  if (sourceURL)
  {
    nsAutoCString extension;
    sourceURL->GetFileExtension(extension);
    if (!extension.IsEmpty())
    {
      nsCOMPtr<nsIUTF8StringEnumerator> encEnum;
      encChannel->GetContentEncodings(getter_AddRefs(encEnum));
      if (encEnum)
      {
        bool hasMore;
        nsresult rv = encEnum->HasMore(&hasMore);
        if (NS_SUCCEEDED(rv) && hasMore)
        {
          nsAutoCString encType;
          rv = encEnum->GetNext(encType);
          if (NS_SUCCEEDED(rv) && !encType.IsEmpty())
          {
            MOZ_ASSERT(mExtProtSvc);
            mExtProtSvc->ApplyDecodingForExtension(extension, encType,
                                                   &applyConversion);
          }
        }
      }
    }
  }

  encChannel->SetApplyConversion( applyConversion );
  return;
}

NS_IMETHODIMP nsExternalAppHandler::OnStartRequest(nsIRequest *request, nsISupports * aCtxt)
{
  NS_PRECONDITION(request, "OnStartRequest without request?");

  // Set mTimeDownloadStarted here as the download has already started and
  // we want to record the start time before showing the filepicker.
  mTimeDownloadStarted = PR_Now();

  mRequest = request;

  nsCOMPtr<nsIChannel> aChannel = do_QueryInterface(request);

  nsresult rv;

  nsCOMPtr<nsIFileChannel> fileChan(do_QueryInterface(request));
  mIsFileChannel = fileChan != nullptr;
  if (!mIsFileChannel) {
    // It's possible that this request came from the child process and the
    // file channel actually lives there. If this returns true, then our
    // mSourceUrl will be an nsIFileURL anyway.
    nsCOMPtr<dom::nsIExternalHelperAppParent> parent(do_QueryInterface(request));
    mIsFileChannel = parent && parent->WasFileChannel();
  }

  // Get content length
  if (aChannel) {
    aChannel->GetContentLength(&mContentLength);
  }

  nsCOMPtr<nsIPropertyBag2> props(do_QueryInterface(request, &rv));
  // Determine whether a new window was opened specifically for this request
  if (props) {
    bool tmp = false;
    props->GetPropertyAsBool(NS_LITERAL_STRING("docshell.newWindowTarget"),
                             &tmp);
    mShouldCloseWindow = tmp;
  }

  // Now get the URI
  if (aChannel) {
    aChannel->GetURI(getter_AddRefs(mSourceUrl));
  }

  // retarget all load notifications to our docloader instead of the original window's docloader...
  RetargetLoadNotifications(request);

  // Check to see if there is a refresh header on the original channel.
  if (mOriginalChannel) {
    nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(mOriginalChannel));
    if (httpChannel) {
      nsAutoCString refreshHeader;
      httpChannel->GetResponseHeader(NS_LITERAL_CSTRING("refresh"),
                                     refreshHeader);
      if (!refreshHeader.IsEmpty()) {
        mShouldCloseWindow = false;
      }
    }
  }

  // Close the underlying DOMWindow if there is no refresh header
  // and it was opened specifically for the download
  MaybeCloseWindow();

  // In an IPC setting, we're allowing the child process, here, to make
  // decisions about decoding the channel (e.g. decompression).  It will
  // still forward the decoded (uncompressed) data back to the parent.
  // Con: Uncompressed data means more IPC overhead.
  // Pros: ExternalHelperAppParent doesn't need to implement nsIEncodedChannel.
  //       Parent process doesn't need to expect CPU time on decompression.
  MaybeApplyDecodingForExtension(aChannel);

  // At this point, the child process has done everything it can usefully do
  // for OnStartRequest.
  if (XRE_IsContentProcess()) {
    return NS_OK;
  }

  rv = SetUpTempFile(aChannel);
  if (NS_FAILED(rv)) {
    nsresult transferError = rv;

    rv = CreateFailedTransfer(aChannel && NS_UsePrivateBrowsing(aChannel));
    if (NS_FAILED(rv)) {
      LOG(("Failed to create transfer to report failure."
           "Will fallback to prompter!"));
    }

    mCanceled = true;
    request->Cancel(transferError);

    nsAutoString path;
    if (mTempFile)
      mTempFile->GetPath(path);

    SendStatusChange(kWriteError, transferError, request, path);

    return NS_OK;
  }

  // Inform channel it is open on behalf of a download to prevent caching.
  nsCOMPtr<nsIHttpChannelInternal> httpInternal = do_QueryInterface(aChannel);
  if (httpInternal) {
    httpInternal->SetChannelIsForDownload(true);
  }

  // now that the temp file is set up, find out if we need to invoke a dialog
  // asking the user what they want us to do with this content...

  // We can get here for three reasons: "can't handle", "sniffed type", or
  // "server sent content-disposition:attachment".  In the first case we want
  // to honor the user's "always ask" pref; in the other two cases we want to
  // honor it only if the default action is "save".  Opening attachments in
  // helper apps by default breaks some websites (especially if the attachment
  // is one part of a multipart document).  Opening sniffed content in helper
  // apps by default introduces security holes that we'd rather not have.

  // So let's find out whether the user wants to be prompted.  If he does not,
  // check mReason and the preferred action to see what we should do.

  bool alwaysAsk = true;
  mMimeInfo->GetAlwaysAskBeforeHandling(&alwaysAsk);
  if (alwaysAsk) {
    // But we *don't* ask if this mimeInfo didn't come from
    // our user configuration datastore and the user has said
    // at some point in the distant past that they don't
    // want to be asked.  The latter fact would have been
    // stored in pref strings back in the old days.

    bool mimeTypeIsInDatastore = false;
    nsCOMPtr<nsIHandlerService> handlerSvc = do_GetService(NS_HANDLERSERVICE_CONTRACTID);
    if (handlerSvc) {
      handlerSvc->Exists(mMimeInfo, &mimeTypeIsInDatastore);
    }
    if (!handlerSvc || !mimeTypeIsInDatastore) {
      nsAutoCString MIMEType;
      mMimeInfo->GetMIMEType(MIMEType);
      if (!GetNeverAskFlagFromPref(NEVER_ASK_FOR_SAVE_TO_DISK_PREF, MIMEType.get())) {
        // Don't need to ask after all.
        alwaysAsk = false;
        // Make sure action matches pref (save to disk).
        mMimeInfo->SetPreferredAction(nsIMIMEInfo::saveToDisk);
      } else if (!GetNeverAskFlagFromPref(NEVER_ASK_FOR_OPEN_FILE_PREF, MIMEType.get())) {
        // Don't need to ask after all.
        alwaysAsk = false;
      }
    }
  }

  int32_t action = nsIMIMEInfo::saveToDisk;
  mMimeInfo->GetPreferredAction( &action );

  // OK, now check why we're here
  if (!alwaysAsk && mReason != nsIHelperAppLauncherDialog::REASON_CANTHANDLE) {
    // Force asking if we're not saving.  See comment back when we fetched the
    // alwaysAsk boolean for details.
    alwaysAsk = (action != nsIMIMEInfo::saveToDisk);
  }

  // if we were told that we _must_ save to disk without asking, all the stuff
  // before this is irrelevant; override it
  if (mForceSave) {
    alwaysAsk = false;
    action = nsIMIMEInfo::saveToDisk;
  }
  
  if (alwaysAsk)
  {
    // Display the dialog
    mDialog = do_CreateInstance(NS_HELPERAPPLAUNCHERDLG_CONTRACTID, &rv);
    NS_ENSURE_SUCCESS(rv, rv);

    // this will create a reference cycle (the dialog holds a reference to us as
    // nsIHelperAppLauncher), which will be broken in Cancel or CreateTransfer.
    rv = mDialog->Show(this, GetDialogParent(), mReason);

    // what do we do if the dialog failed? I guess we should call Cancel and abort the load....
  }
  else
  {

    // We need to do the save/open immediately, then.
#ifdef XP_WIN
    /* We need to see whether the file we've got here could be
     * executable.  If it could, we had better not try to open it!
     * We can skip this check, though, if we have a setting to open in a
     * helper app.
     * This code mirrors the code in
     * nsExternalAppHandler::LaunchWithApplication so that what we
     * test here is as close as possible to what will really be
     * happening if we decide to execute
     */
    nsCOMPtr<nsIHandlerApp> prefApp;
    mMimeInfo->GetPreferredApplicationHandler(getter_AddRefs(prefApp));
    if (action != nsIMIMEInfo::useHelperApp || !prefApp) {
      nsCOMPtr<nsIFile> fileToTest;
      GetTargetFile(getter_AddRefs(fileToTest));
      if (fileToTest) {
        bool isExecutable;
        rv = fileToTest->IsExecutable(&isExecutable);
        if (NS_FAILED(rv) || isExecutable) {  // checking NS_FAILED, because paranoia is good
          action = nsIMIMEInfo::saveToDisk;
        }
      } else {   // Paranoia is good here too, though this really should not happen
        NS_WARNING("GetDownloadInfo returned a null file after the temp file has been set up! ");
        action = nsIMIMEInfo::saveToDisk;
      }
    }

#endif
    if (action == nsIMIMEInfo::useHelperApp ||
        action == nsIMIMEInfo::useSystemDefault) {
        rv = LaunchWithApplication(nullptr, false);
    } else {
        rv = SaveToDisk(nullptr, false);
    }
  }

  return NS_OK;
}

// Convert error info into proper message text and send OnStatusChange
// notification to the dialog progress listener or nsITransfer implementation.
void nsExternalAppHandler::SendStatusChange(ErrorType type, nsresult rv, nsIRequest *aRequest, const nsAFlatString &path)
{
    nsAutoString msgId;
    switch (rv) {
    case NS_ERROR_OUT_OF_MEMORY:
        // No memory
        msgId.AssignLiteral("noMemory");
        break;

    case NS_ERROR_FILE_DISK_FULL:
    case NS_ERROR_FILE_NO_DEVICE_SPACE:
        // Out of space on target volume.
        msgId.AssignLiteral("diskFull");
        break;

    case NS_ERROR_FILE_READ_ONLY:
        // Attempt to write to read/only file.
        msgId.AssignLiteral("readOnly");
        break;

    case NS_ERROR_FILE_ACCESS_DENIED:
        if (type == kWriteError) {
          // Attempt to write without sufficient permissions.
          msgId.AssignLiteral("accessError");
        } else {
          msgId.AssignLiteral("launchError");
        }
        break;

    case NS_ERROR_FILE_NOT_FOUND:
    case NS_ERROR_FILE_TARGET_DOES_NOT_EXIST:
    case NS_ERROR_FILE_UNRECOGNIZED_PATH:
        // Helper app not found, let's verify this happened on launch
        if (type == kLaunchError) {
          msgId.AssignLiteral("helperAppNotFound");
          break;
        }
        MOZ_FALLTHROUGH;

    default:
        // Generic read/write/launch error message.
        switch (type) {
        case kReadError:
          msgId.AssignLiteral("readError");
          break;
        case kWriteError:
          msgId.AssignLiteral("writeError");
          break;
        case kLaunchError:
          msgId.AssignLiteral("launchError");
          break;
        }
        break;
    }

    MOZ_LOG(nsExternalHelperAppService::mLog, LogLevel::Error,
        ("Error: %s, type=%i, listener=0x%p, transfer=0x%p, rv=0x%08X\n",
         NS_LossyConvertUTF16toASCII(msgId).get(), type, mDialogProgressListener.get(), mTransfer.get(), rv));

    MOZ_LOG(nsExternalHelperAppService::mLog, LogLevel::Error,
        ("       path='%s'\n", NS_ConvertUTF16toUTF8(path).get()));

    // Get properties file bundle and extract status string.
    nsCOMPtr<nsIStringBundleService> stringService =
        mozilla::services::GetStringBundleService();
    if (stringService) {
        nsCOMPtr<nsIStringBundle> bundle;
        if (NS_SUCCEEDED(stringService->CreateBundle("chrome://global/locale/nsWebBrowserPersist.properties",
                         getter_AddRefs(bundle)))) {
            nsXPIDLString msgText;
            const char16_t *strings[] = { path.get() };
            if (NS_SUCCEEDED(bundle->FormatStringFromName(msgId.get(), strings, 1,
                                                          getter_Copies(msgText)))) {
              if (mDialogProgressListener) {
                // We have a listener, let it handle the error.
                mDialogProgressListener->OnStatusChange(nullptr, (type == kReadError) ? aRequest : nullptr, rv, msgText);
              } else if (mTransfer) {
                mTransfer->OnStatusChange(nullptr, (type == kReadError) ? aRequest : nullptr, rv, msgText);
              } else if (XRE_IsParentProcess()) {
                // We don't have a listener.  Simply show the alert ourselves.
                nsresult qiRv;
                nsCOMPtr<nsIPrompt> prompter(do_GetInterface(GetDialogParent(), &qiRv));
                nsXPIDLString title;
                bundle->FormatStringFromName(u"title",
                                             strings,
                                             1,
                                             getter_Copies(title));

                MOZ_LOG(nsExternalHelperAppService::mLog, LogLevel::Debug,
                       ("mContentContext=0x%p, prompter=0x%p, qi rv=0x%08X, title='%s', msg='%s'",
                       mContentContext.get(),
                       prompter.get(),
                       qiRv,
                       NS_ConvertUTF16toUTF8(title).get(),
                       NS_ConvertUTF16toUTF8(msgText).get()));

                // If we didn't have a prompter we will try and get a window
                // instead, get it's docshell and use it to alert the user.
                if (!prompter) {
                  nsCOMPtr<nsPIDOMWindowOuter> window(do_GetInterface(GetDialogParent()));
                  if (!window || !window->GetDocShell()) {
                    return;
                  }

                  prompter = do_GetInterface(window->GetDocShell(), &qiRv);

                  MOZ_LOG(nsExternalHelperAppService::mLog, LogLevel::Debug,
                         ("No prompter from mContentContext, using DocShell, " \
                          "window=0x%p, docShell=0x%p, " \
                          "prompter=0x%p, qi rv=0x%08X",
                          window.get(),
                          window->GetDocShell(),
                          prompter.get(),
                          qiRv));

                  // If we still don't have a prompter, there's nothing else we
                  // can do so just return.
                  if (!prompter) {
                    MOZ_LOG(nsExternalHelperAppService::mLog, LogLevel::Error,
                           ("No prompter from DocShell, no way to alert user"));
                    return;
                  }
                }

                // We should always have a prompter at this point.
                prompter->Alert(title, msgText);
              }
            }
        }
    }
}

NS_IMETHODIMP
nsExternalAppHandler::OnDataAvailable(nsIRequest *request, nsISupports * aCtxt,
                                      nsIInputStream * inStr,
                                      uint64_t sourceOffset, uint32_t count)
{
  nsresult rv = NS_OK;
  // first, check to see if we've been canceled....
  if (mCanceled || !mSaver) {
    // then go cancel our underlying channel too
    return request->Cancel(NS_BINDING_ABORTED);
  }

  // read the data out of the stream and write it to the temp file.
  if (count > 0) {
    mProgress += count;

    nsCOMPtr<nsIStreamListener> saver = do_QueryInterface(mSaver);
    rv = saver->OnDataAvailable(request, aCtxt, inStr, sourceOffset, count);
    if (NS_SUCCEEDED(rv)) {
      // Send progress notification.
      if (mTransfer) {
        mTransfer->OnProgressChange64(nullptr, request, mProgress,
                                      mContentLength, mProgress,
                                      mContentLength);
      }
    } else {
      // An error occurred, notify listener.
      nsAutoString tempFilePath;
      if (mTempFile) {
        mTempFile->GetPath(tempFilePath);
      }
      SendStatusChange(kReadError, rv, request, tempFilePath);

      // Cancel the download.
      Cancel(rv);
    }
  }
  return rv;
}

NS_IMETHODIMP nsExternalAppHandler::OnStopRequest(nsIRequest *request, nsISupports *aCtxt,
                                                  nsresult aStatus)
{
  LOG(("nsExternalAppHandler::OnStopRequest\n"
       "  mCanceled=%d, mTransfer=0x%p, aStatus=0x%08X\n",
       mCanceled, mTransfer.get(), aStatus));

  mStopRequestIssued = true;

  // Cancel if the request did not complete successfully.
  if (!mCanceled && NS_FAILED(aStatus)) {
    // Send error notification.
    nsAutoString tempFilePath;
    if (mTempFile)
      mTempFile->GetPath(tempFilePath);
    SendStatusChange( kReadError, aStatus, request, tempFilePath );

    Cancel(aStatus);
  }

  // first, check to see if we've been canceled....
  if (mCanceled || !mSaver) {
    return NS_OK;
  }

  return mSaver->Finish(NS_OK);
}

NS_IMETHODIMP
nsExternalAppHandler::OnTargetChange(nsIBackgroundFileSaver *aSaver,
                                     nsIFile *aTarget)
{
  return NS_OK;
}

NS_IMETHODIMP
nsExternalAppHandler::OnSaveComplete(nsIBackgroundFileSaver *aSaver,
                                     nsresult aStatus)
{
  LOG(("nsExternalAppHandler::OnSaveComplete\n"
       "  aSaver=0x%p, aStatus=0x%08X, mCanceled=%d, mTransfer=0x%p\n",
       aSaver, aStatus, mCanceled, mTransfer.get()));

  if (!mCanceled) {
    // Save the hash and signature information
    (void)mSaver->GetSha256Hash(mHash);
    (void)mSaver->GetSignatureInfo(getter_AddRefs(mSignatureInfo));

    // Free the reference that the saver keeps on us, even if we couldn't get
    // the hash.
    mSaver = nullptr;

    // Save the redirect information.
    nsCOMPtr<nsIChannel> channel = do_QueryInterface(mRequest);
    if (channel) {
      nsCOMPtr<nsILoadInfo> loadInfo = channel->GetLoadInfo();
      if (loadInfo) {
        nsresult rv = NS_OK;
        nsCOMPtr<nsIMutableArray> redirectChain =
          do_CreateInstance(NS_ARRAY_CONTRACTID, &rv);
        NS_ENSURE_SUCCESS(rv, rv);
        LOG(("nsExternalAppHandler: Got %u redirects\n", loadInfo->RedirectChain().Length()));
        for (nsIPrincipal* principal : loadInfo->RedirectChain()) {
          redirectChain->AppendElement(principal, false);
        }
        mRedirects = redirectChain;
      }
    }

    if (NS_FAILED(aStatus)) {
      nsAutoString path;
      mTempFile->GetPath(path);

      // It may happen when e10s is enabled that there will be no transfer
      // object available to communicate status as expected by the system.
      // Let's try and create a temporary transfer object to take care of this
      // for us, we'll fall back to using the prompt service if we absolutely
      // have to.
      if (!mTransfer) {
        // We don't care if this fails.
        CreateFailedTransfer(channel && NS_UsePrivateBrowsing(channel));
      }

      SendStatusChange(kWriteError, aStatus, nullptr, path);
      if (!mCanceled)
        Cancel(aStatus);
      return NS_OK;
    }
  }

  // Notify the transfer object that we are done if the user has chosen an
  // action. If the user hasn't chosen an action, the progress listener
  // (nsITransfer) will be notified in CreateTransfer.
  if (mTransfer) {
    NotifyTransfer(aStatus);
  }

  return NS_OK;
}

void nsExternalAppHandler::NotifyTransfer(nsresult aStatus)
{
  MOZ_ASSERT(NS_IsMainThread(), "Must notify on main thread");
  MOZ_ASSERT(mTransfer, "We must have an nsITransfer");

  LOG(("Notifying progress listener"));

  if (NS_SUCCEEDED(aStatus)) {
    (void)mTransfer->SetSha256Hash(mHash);
    (void)mTransfer->SetSignatureInfo(mSignatureInfo);
    (void)mTransfer->SetRedirects(mRedirects);
    (void)mTransfer->OnProgressChange64(nullptr, nullptr, mProgress,
      mContentLength, mProgress, mContentLength);
  }

  (void)mTransfer->OnStateChange(nullptr, nullptr,
    nsIWebProgressListener::STATE_STOP |
    nsIWebProgressListener::STATE_IS_REQUEST |
    nsIWebProgressListener::STATE_IS_NETWORK, aStatus);

  // This nsITransfer object holds a reference to us (we are its observer), so
  // we need to release the reference to break a reference cycle (and therefore
  // to prevent leaking).  We do this even if the previous calls failed.
  mTransfer = nullptr;
}

NS_IMETHODIMP nsExternalAppHandler::GetMIMEInfo(nsIMIMEInfo ** aMIMEInfo)
{
  *aMIMEInfo = mMimeInfo;
  NS_ADDREF(*aMIMEInfo);
  return NS_OK;
}

NS_IMETHODIMP nsExternalAppHandler::GetSource(nsIURI ** aSourceURI)
{
  NS_ENSURE_ARG(aSourceURI);
  *aSourceURI = mSourceUrl;
  NS_IF_ADDREF(*aSourceURI);
  return NS_OK;
}

NS_IMETHODIMP nsExternalAppHandler::GetSuggestedFileName(nsAString& aSuggestedFileName)
{
  aSuggestedFileName = mSuggestedFileName;
  return NS_OK;
}

nsresult nsExternalAppHandler::CreateTransfer()
{
  LOG(("nsExternalAppHandler::CreateTransfer"));

  MOZ_ASSERT(NS_IsMainThread(), "Must create transfer on main thread");
  // We are back from the helper app dialog (where the user chooses to save or
  // open), but we aren't done processing the load. in this case, throw up a
  // progress dialog so the user can see what's going on.
  // Also, release our reference to mDialog. We don't need it anymore, and we
  // need to break the reference cycle.
  mDialog = nullptr;
  if (!mDialogProgressListener) {
    NS_WARNING("The dialog should nullify the dialog progress listener");
  }
  nsresult rv;

  // We must be able to create an nsITransfer object. If not, it doesn't matter
  // much that we can't launch the helper application or save to disk. Work on
  // a local copy rather than mTransfer until we know we succeeded, to make it
  // clearer that this function is re-entrant.
  nsCOMPtr<nsITransfer> transfer = do_CreateInstance(
    NS_TRANSFER_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  // Initialize the download
  nsCOMPtr<nsIURI> target;
  rv = NS_NewFileURI(getter_AddRefs(target), mFinalFileDestination);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIChannel> channel = do_QueryInterface(mRequest);

  rv = transfer->Init(mSourceUrl, target, EmptyString(),
                       mMimeInfo, mTimeDownloadStarted, mTempFile, this,
                       channel && NS_UsePrivateBrowsing(channel));
  NS_ENSURE_SUCCESS(rv, rv);

  // Now let's add the download to history
  nsCOMPtr<nsIDownloadHistory> dh(do_GetService(NS_DOWNLOADHISTORY_CONTRACTID));
  if (dh) {
    if (channel && !NS_UsePrivateBrowsing(channel)) {
      nsCOMPtr<nsIURI> referrer;
      NS_GetReferrerFromChannel(channel, getter_AddRefs(referrer));

      dh->AddDownload(mSourceUrl, referrer, mTimeDownloadStarted, target);
    }
  }

  // If we were cancelled since creating the transfer, just return. It is
  // always ok to return NS_OK if we are cancelled. Callers of this function
  // must call Cancel if CreateTransfer fails, but there's no need to cancel
  // twice.
  if (mCanceled) {
    return NS_OK;
  }
  rv = transfer->OnStateChange(nullptr, mRequest,
    nsIWebProgressListener::STATE_START |
    nsIWebProgressListener::STATE_IS_REQUEST |
    nsIWebProgressListener::STATE_IS_NETWORK, NS_OK);
  NS_ENSURE_SUCCESS(rv, rv);

  if (mCanceled) {
    return NS_OK;
  }

  mRequest = nullptr;
  // Finally, save the transfer to mTransfer.
  mTransfer = transfer;
  transfer = nullptr;

  // While we were bringing up the progress dialog, we actually finished
  // processing the url. If that's the case then mStopRequestIssued will be
  // true and OnSaveComplete has been called.
  if (mStopRequestIssued && !mSaver && mTransfer) {
    NotifyTransfer(NS_OK);
  }

  return rv;
}

nsresult nsExternalAppHandler::CreateFailedTransfer(bool aIsPrivateBrowsing)
{
  nsresult rv;
  nsCOMPtr<nsITransfer> transfer =
    do_CreateInstance(NS_TRANSFER_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  // If we don't have a download directory we're kinda screwed but it's OK
  // we'll still report the error via the prompter.
  nsCOMPtr<nsIFile> pseudoFile;
  rv = GetDownloadDirectory(getter_AddRefs(pseudoFile), true);
  NS_ENSURE_SUCCESS(rv, rv);

  // Append the default suggested filename. If the user restarts the transfer
  // we will re-trigger a filename check anyway to ensure that it is unique.
  rv = pseudoFile->Append(mSuggestedFileName);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIURI> pseudoTarget;
  rv = NS_NewFileURI(getter_AddRefs(pseudoTarget), pseudoFile);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = transfer->Init(mSourceUrl, pseudoTarget, EmptyString(),
                      mMimeInfo, mTimeDownloadStarted, nullptr, this,
                      aIsPrivateBrowsing);
  NS_ENSURE_SUCCESS(rv, rv);

  // Our failed transfer is ready.
  mTransfer = transfer.forget();

  return NS_OK;
}

nsresult nsExternalAppHandler::SaveDestinationAvailable(nsIFile * aFile)
{
  if (aFile)
    ContinueSave(aFile);
  else
    Cancel(NS_BINDING_ABORTED);

  return NS_OK;
}

void nsExternalAppHandler::RequestSaveDestination(const nsAFlatString &aDefaultFile, const nsAFlatString &aFileExtension)
{
  // Display the dialog
  // XXX Convert to use file picker? No, then embeddors could not do any sort of
  // "AutoDownload" w/o showing a prompt
  nsresult rv = NS_OK;
  if (!mDialog) {
    // Get helper app launcher dialog.
    mDialog = do_CreateInstance(NS_HELPERAPPLAUNCHERDLG_CONTRACTID, &rv);
    if (rv != NS_OK) {
      Cancel(NS_BINDING_ABORTED);
      return;
    }
  }

  // we want to explicitly unescape aDefaultFile b4 passing into the dialog. we can't unescape
  // it because the dialog is implemented by a JS component which doesn't have a window so no unescape routine is defined...

  // Now, be sure to keep |this| alive, and the dialog
  // If we don't do this, users that close the helper app dialog while the file
  // picker is up would cause Cancel() to be called, and the dialog would be
  // released, which would release this object too, which would crash.
  // See Bug 249143
  RefPtr<nsExternalAppHandler> kungFuDeathGrip(this);
  nsCOMPtr<nsIHelperAppLauncherDialog> dlg(mDialog);

  rv = dlg->PromptForSaveToFileAsync(this,
                                     GetDialogParent(),
                                     aDefaultFile.get(),
                                     aFileExtension.get(),
                                     mForceSave);
  if (NS_FAILED(rv)) {
    Cancel(NS_BINDING_ABORTED);
  }
}

// SaveToDisk should only be called by the helper app dialog which allows
// the user to say launch with application or save to disk. It doesn't actually
// perform the save, it just prompts for the destination file name.
NS_IMETHODIMP nsExternalAppHandler::SaveToDisk(nsIFile * aNewFileLocation, bool aRememberThisPreference)
{
  if (mCanceled)
    return NS_OK;

  mMimeInfo->SetPreferredAction(nsIMIMEInfo::saveToDisk);

  if (!aNewFileLocation) {
    if (mSuggestedFileName.IsEmpty())
      RequestSaveDestination(mTempLeafName, mTempFileExtension);
    else
    {
      nsAutoString fileExt;
      int32_t pos = mSuggestedFileName.RFindChar('.');
      if (pos >= 0)
        mSuggestedFileName.Right(fileExt, mSuggestedFileName.Length() - pos);
      if (fileExt.IsEmpty())
        fileExt = mTempFileExtension;

      RequestSaveDestination(mSuggestedFileName, fileExt);
    }
  } else {
    ContinueSave(aNewFileLocation);
  }

  return NS_OK;
}
nsresult nsExternalAppHandler::ContinueSave(nsIFile * aNewFileLocation)
{
  if (mCanceled)
    return NS_OK;

  NS_PRECONDITION(aNewFileLocation, "Must be called with a non-null file");

  nsresult rv = NS_OK;
  nsCOMPtr<nsIFile> fileToUse = do_QueryInterface(aNewFileLocation);
  mFinalFileDestination = do_QueryInterface(fileToUse);

  // Move what we have in the final directory, but append .part
  // to it, to indicate that it's unfinished.  Do not call SetTarget on the
  // saver if we are done (Finish has been called) but OnSaverComplete has not
  // been called.
  if (mFinalFileDestination && mSaver && !mStopRequestIssued)
  {
    nsCOMPtr<nsIFile> movedFile;
    mFinalFileDestination->Clone(getter_AddRefs(movedFile));
    if (movedFile) {
      // Get the old leaf name and append .part to it
      nsAutoString name;
      mFinalFileDestination->GetLeafName(name);
      name.AppendLiteral(".part");
      movedFile->SetLeafName(name);

      rv = mSaver->SetTarget(movedFile, true);
      if (NS_FAILED(rv)) {
        nsAutoString path;
        mTempFile->GetPath(path);
        SendStatusChange(kWriteError, rv, nullptr, path);
        Cancel(rv);
        return NS_OK;
      }

      mTempFile = movedFile;
    }
  }

  // The helper app dialog has told us what to do and we have a final file
  // destination.
  rv = CreateTransfer();
  // If we fail to create the transfer, Cancel.
  if (NS_FAILED(rv)) {
    Cancel(rv);
    return rv;
  }

  // now that the user has chosen the file location to save to, it's okay to fire the refresh tag
  // if there is one. We don't want to do this before the save as dialog goes away because this dialog
  // is modal and we do bad things if you try to load a web page in the underlying window while a modal
  // dialog is still up.
  ProcessAnyRefreshTags();

  return NS_OK;
}


// LaunchWithApplication should only be called by the helper app dialog which
// allows the user to say launch with application or save to disk. It doesn't
// actually perform launch with application.
NS_IMETHODIMP nsExternalAppHandler::LaunchWithApplication(nsIFile * aApplication, bool aRememberThisPreference)
{
  if (mCanceled)
    return NS_OK;

  // user has chosen to launch using an application, fire any refresh tags now...
  ProcessAnyRefreshTags(); 
  
  if (mMimeInfo && aApplication) {
    PlatformLocalHandlerApp_t *handlerApp =
      new PlatformLocalHandlerApp_t(EmptyString(), aApplication);
    mMimeInfo->SetPreferredApplicationHandler(handlerApp);
  }

  // Now check if the file is local, in which case we won't bother with saving
  // it to a temporary directory and just launch it from where it is
  nsCOMPtr<nsIFileURL> fileUrl(do_QueryInterface(mSourceUrl));
  if (fileUrl && mIsFileChannel) {
    Cancel(NS_BINDING_ABORTED);
    nsCOMPtr<nsIFile> file;
    nsresult rv = fileUrl->GetFile(getter_AddRefs(file));

    if (NS_SUCCEEDED(rv)) {
      rv = mMimeInfo->LaunchWithFile(file);
      if (NS_SUCCEEDED(rv))
        return NS_OK;
    }
    nsAutoString path;
    if (file)
      file->GetPath(path);
    // If we get here, an error happened
    SendStatusChange(kLaunchError, rv, nullptr, path);
    return rv;
  }

  // Now that the user has elected to launch the downloaded file with a helper
  // app, we're justified in removing the 'salted' name.  We'll rename to what
  // was specified in mSuggestedFileName after the download is done prior to
  // launching the helper app.  So that any existing file of that name won't be
  // overwritten we call CreateUnique().  Also note that we use the same
  // directory as originally downloaded so nsDownload can rename in place
  // later.
  nsCOMPtr<nsIFile> fileToUse;
  (void) GetDownloadDirectory(getter_AddRefs(fileToUse));

  if (mSuggestedFileName.IsEmpty()) {
    // Keep using the leafname of the temp file, since we're just starting a helper
    mSuggestedFileName = mTempLeafName;
  }

#ifdef XP_WIN
  fileToUse->Append(mSuggestedFileName + mTempFileExtension);
#else
  fileToUse->Append(mSuggestedFileName);  
#endif

  nsresult rv = fileToUse->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);
  if(NS_SUCCEEDED(rv)) {
    mFinalFileDestination = do_QueryInterface(fileToUse);
    // launch the progress window now that the user has picked the desired action.
    rv = CreateTransfer();
    if (NS_FAILED(rv)) {
      Cancel(rv);
    }
  } else {
    // Cancel the download and report an error.  We do not want to end up in
    // a state where it appears that we have a normal download that is
    // pointing to a file that we did not actually create.
    nsAutoString path;
    mTempFile->GetPath(path);
    SendStatusChange(kWriteError, rv, nullptr, path);
    Cancel(rv);
  }
  return rv;
}

NS_IMETHODIMP nsExternalAppHandler::Cancel(nsresult aReason)
{
  NS_ENSURE_ARG(NS_FAILED(aReason));

  if (mCanceled) {
    return NS_OK;
  }
  mCanceled = true;

  if (mSaver) {
    // We are still writing to the target file.  Give the saver a chance to
    // close the target file, then notify the transfer object if necessary in
    // the OnSaveComplete callback.
    mSaver->Finish(aReason);
    mSaver = nullptr;
  } else {
    if (mStopRequestIssued && mTempFile) {
      // This branch can only happen when the user cancels the helper app dialog
      // when the request has completed. The temp file has to be removed here,
      // because mSaver has been released at that time with the temp file left.
      (void)mTempFile->Remove(false);
    }

    // Notify the transfer object that the download has been canceled, if the
    // user has already chosen an action and we didn't notify already.
    if (mTransfer) {
      NotifyTransfer(aReason);
    }
  }

  // Break our reference cycle with the helper app dialog (set up in
  // OnStartRequest)
  mDialog = nullptr;

  mRequest = nullptr;

  // Release the listener, to break the reference cycle with it (we are the
  // observer of the listener).
  mDialogProgressListener = nullptr;

  return NS_OK;
}

void nsExternalAppHandler::ProcessAnyRefreshTags()
{
   // one last thing, try to see if the original window context supports a refresh interface...
   // Sometimes, when you download content that requires an external handler, there is
   // a refresh header associated with the download. This refresh header points to a page
   // the content provider wants the user to see after they download the content. How do we
   // pass this refresh information back to the caller? For now, try to get the refresh URI
   // interface. If the window context where the request originated came from supports this
   // then we can force it to process the refresh information (if there is any) from this channel.
   if (mContentContext && mOriginalChannel) {
     nsCOMPtr<nsIRefreshURI> refreshHandler (do_GetInterface(mContentContext));
     if (refreshHandler) {
        refreshHandler->SetupRefreshURI(mOriginalChannel);
     }
     mOriginalChannel = nullptr;
   }
}

bool nsExternalAppHandler::GetNeverAskFlagFromPref(const char * prefName, const char * aContentType)
{
  // Search the obsolete pref strings.
  nsAdoptingCString prefCString = Preferences::GetCString(prefName);
  if (prefCString.IsEmpty()) {
    // Default is true, if not found in the pref string.
    return true;
  }

  NS_UnescapeURL(prefCString);
  nsACString::const_iterator start, end;
  prefCString.BeginReading(start);
  prefCString.EndReading(end);
  return !CaseInsensitiveFindInReadable(nsDependentCString(aContentType),
                                        start, end);
}

nsresult nsExternalAppHandler::MaybeCloseWindow()
{
  nsCOMPtr<nsPIDOMWindowOuter> window = do_GetInterface(mContentContext);
  NS_ENSURE_STATE(window);

  if (mShouldCloseWindow) {
    // Reset the window context to the opener window so that the dependent
    // dialogs have a parent
    nsCOMPtr<nsPIDOMWindowOuter> opener = window->GetOpener();

    if (opener && !opener->Closed()) {
      mContentContext = do_GetInterface(opener);

      // Now close the old window.  Do it on a timer so that we don't run
      // into issues trying to close the window before it has fully opened.
      NS_ASSERTION(!mTimer, "mTimer was already initialized once!");
      mTimer = do_CreateInstance("@mozilla.org/timer;1");
      if (!mTimer) {
        return NS_ERROR_FAILURE;
      }

      mTimer->InitWithCallback(this, 0, nsITimer::TYPE_ONE_SHOT);
      mWindowToClose = window;
    }
  }

  return NS_OK;
}

NS_IMETHODIMP
nsExternalAppHandler::Notify(nsITimer* timer)
{
  NS_ASSERTION(mWindowToClose, "No window to close after timer fired");

  mWindowToClose->Close();
  mWindowToClose = nullptr;
  mTimer = nullptr;

  return NS_OK;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////////
// The following section contains our nsIMIMEService implementation and related methods.
//
//////////////////////////////////////////////////////////////////////////////////////////////////////////////

// nsIMIMEService methods
NS_IMETHODIMP nsExternalHelperAppService::GetFromTypeAndExtension(const nsACString& aMIMEType, const nsACString& aFileExt, nsIMIMEInfo **_retval) 
{
  NS_PRECONDITION(!aMIMEType.IsEmpty() ||
                  !aFileExt.IsEmpty(), 
                  "Give me something to work with");
  LOG(("Getting mimeinfo from type '%s' ext '%s'\n",
        PromiseFlatCString(aMIMEType).get(), PromiseFlatCString(aFileExt).get()));

  *_retval = nullptr;

  // OK... we need a type. Get one.
  nsAutoCString typeToUse(aMIMEType);
  if (typeToUse.IsEmpty()) {
    nsresult rv = GetTypeFromExtension(aFileExt, typeToUse);
    if (NS_FAILED(rv))
      return NS_ERROR_NOT_AVAILABLE;
  }

  // We promise to only send lower case mime types to the OS
  ToLowerCase(typeToUse);

  // (1) Ask the OS for a mime info
  bool found;
  *_retval = GetMIMEInfoFromOS(typeToUse, aFileExt, &found).take();
  LOG(("OS gave back 0x%p - found: %i\n", *_retval, found));
  // If we got no mimeinfo, something went wrong. Probably lack of memory.
  if (!*_retval)
    return NS_ERROR_OUT_OF_MEMORY;

  // (2) Now, let's see if we can find something in our datastore
  // This will not overwrite the OS information that interests us
  // (i.e. default application, default app. description)
  nsresult rv;
  nsCOMPtr<nsIHandlerService> handlerSvc = do_GetService(NS_HANDLERSERVICE_CONTRACTID);
  if (handlerSvc) {
    bool hasHandler = false;
    (void) handlerSvc->Exists(*_retval, &hasHandler);
    if (hasHandler) {
      rv = handlerSvc->FillHandlerInfo(*_retval, EmptyCString());
      LOG(("Data source: Via type: retval 0x%08x\n", rv));
    } else {
      rv = NS_ERROR_NOT_AVAILABLE;
    }
 
    found = found || NS_SUCCEEDED(rv);

    if (!found || NS_FAILED(rv)) {
      // No type match, try extension match
      if (!aFileExt.IsEmpty()) {
        nsAutoCString overrideType;
        rv = handlerSvc->GetTypeFromExtension(aFileExt, overrideType);
        if (NS_SUCCEEDED(rv) && !overrideType.IsEmpty()) {
          // We can't check handlerSvc->Exists() here, because we have a
          // overideType. That's ok, it just results in some console noise.
          // (If there's no handler for the override type, it throws)
          rv = handlerSvc->FillHandlerInfo(*_retval, overrideType);
          LOG(("Data source: Via ext: retval 0x%08x\n", rv));
          found = found || NS_SUCCEEDED(rv);
        }
      }
    }
  }

  // (3) No match yet. Ask extras.
  if (!found) {
    rv = NS_ERROR_FAILURE;
#ifdef XP_WIN
    /* XXX Gross hack to wallpaper over the most common Win32
     * extension issues caused by the fix for bug 116938.  See bug
     * 120327, comment 271 for why this is needed.  Not even sure we
     * want to remove this once we have fixed all this stuff to work
     * right; any info we get from extras on this type is pretty much
     * useless....
     */
    if (!typeToUse.Equals(APPLICATION_OCTET_STREAM, nsCaseInsensitiveCStringComparator()))
#endif
      rv = FillMIMEInfoForMimeTypeFromExtras(typeToUse, *_retval);
    LOG(("Searched extras (by type), rv 0x%08X\n", rv));
    // If that didn't work out, try file extension from extras
    if (NS_FAILED(rv) && !aFileExt.IsEmpty()) {
      rv = FillMIMEInfoForExtensionFromExtras(aFileExt, *_retval);
      LOG(("Searched extras (by ext), rv 0x%08X\n", rv));
    }
    // If that still didn't work, set the file description to "ext File"
    if (NS_FAILED(rv) && !aFileExt.IsEmpty()) {
      // XXXzpao This should probably be localized
      nsAutoCString desc(aFileExt);
      desc.AppendLiteral(" File");
      (*_retval)->SetDescription(NS_ConvertASCIItoUTF16(desc));
      LOG(("Falling back to 'File' file description\n"));
    }
  }

  // Finally, check if we got a file extension and if yes, if it is an
  // extension on the mimeinfo, in which case we want it to be the primary one
  if (!aFileExt.IsEmpty()) {
    bool matches = false;
    (*_retval)->ExtensionExists(aFileExt, &matches);
    LOG(("Extension '%s' matches mime info: %i\n", PromiseFlatCString(aFileExt).get(), matches));
    if (matches)
      (*_retval)->SetPrimaryExtension(aFileExt);
  }

  if (LOG_ENABLED()) {
    nsAutoCString type;
    (*_retval)->GetMIMEType(type);

    nsAutoCString ext;
    (*_retval)->GetPrimaryExtension(ext);
    LOG(("MIME Info Summary: Type '%s', Primary Ext '%s'\n", type.get(), ext.get()));
  }

  return NS_OK;
}

NS_IMETHODIMP
nsExternalHelperAppService::GetTypeFromExtension(const nsACString& aFileExt,
                                                 nsACString& aContentType)
{
  // OK. We want to try the following sources of mimetype information, in this order:
  // 1. defaultMimeEntries array
  // 2. OS-provided information
  // 3. our "extras" array
  // 4. Information from plugins
  // 5. The "ext-to-type-mapping" category
  // Note that, we are intentionally not looking at the handler service, because
  // that can be affected by websites, which leads to undesired behavior.

  // Early return if called with an empty extension parameter
  if (aFileExt.IsEmpty()) {
    return NS_ERROR_NOT_AVAILABLE;
  }

  // First of all, check our default entries
  for (auto& entry : defaultMimeEntries) {
    if (aFileExt.LowerCaseEqualsASCII(entry.mFileExtension)) {
      aContentType = entry.mMimeType;
      return NS_OK;
    }
  }

  // Ask OS.
  if (GetMIMETypeFromOSForExtension(aFileExt, aContentType)) {
    return NS_OK;
  }

  // Check extras array.
  bool found = GetTypeFromExtras(aFileExt, aContentType);
  if (found) {
    return NS_OK;
  }

  // Try the plugins
  RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
  if (pluginHost &&
      pluginHost->HavePluginForExtension(aFileExt, aContentType)) {
    return NS_OK;
  }

  // Let's see if an extension added something
  nsCOMPtr<nsICategoryManager> catMan(
    do_GetService("@mozilla.org/categorymanager;1"));
  if (catMan) {
    // The extension in the category entry is always stored as lowercase
    nsAutoCString lowercaseFileExt(aFileExt);
    ToLowerCase(lowercaseFileExt);
    // Read the MIME type from the category entry, if available
    nsXPIDLCString type;
    nsresult rv = catMan->GetCategoryEntry("ext-to-type-mapping",
                                           lowercaseFileExt.get(),
                                           getter_Copies(type));
    if (NS_SUCCEEDED(rv)) {
      aContentType = type;
      return NS_OK;
    }
  }

  return NS_ERROR_NOT_AVAILABLE;
}

NS_IMETHODIMP nsExternalHelperAppService::GetPrimaryExtension(const nsACString& aMIMEType, const nsACString& aFileExt, nsACString& _retval)
{
  NS_ENSURE_ARG(!aMIMEType.IsEmpty());

  nsCOMPtr<nsIMIMEInfo> mi;
  nsresult rv = GetFromTypeAndExtension(aMIMEType, aFileExt, getter_AddRefs(mi));
  if (NS_FAILED(rv))
    return rv;

  return mi->GetPrimaryExtension(_retval);
}

NS_IMETHODIMP nsExternalHelperAppService::GetTypeFromURI(nsIURI *aURI, nsACString& aContentType) 
{
  NS_ENSURE_ARG_POINTER(aURI);
  nsresult rv = NS_ERROR_NOT_AVAILABLE;
  aContentType.Truncate();

  // First look for a file to use.  If we have one, we just use that.
  nsCOMPtr<nsIFileURL> fileUrl = do_QueryInterface(aURI);
  if (fileUrl) {
    nsCOMPtr<nsIFile> file;
    rv = fileUrl->GetFile(getter_AddRefs(file));
    if (NS_SUCCEEDED(rv)) {
      rv = GetTypeFromFile(file, aContentType);
      if (NS_SUCCEEDED(rv)) {
        // we got something!
        return rv;
      }
    }
  }

  // Now try to get an nsIURL so we don't have to do our own parsing
  nsCOMPtr<nsIURL> url = do_QueryInterface(aURI);
  if (url) {
    nsAutoCString ext;
    rv = url->GetFileExtension(ext);
    if (NS_FAILED(rv))
      return rv;
    if (ext.IsEmpty())
      return NS_ERROR_NOT_AVAILABLE;

    UnescapeFragment(ext, url, ext);

    return GetTypeFromExtension(ext, aContentType);
  }
    
  // no url, let's give the raw spec a shot
  nsAutoCString specStr;
  rv = aURI->GetSpec(specStr);
  if (NS_FAILED(rv))
    return rv;
  UnescapeFragment(specStr, aURI, specStr);

  // find the file extension (if any)
  int32_t extLoc = specStr.RFindChar('.');
  int32_t specLength = specStr.Length();
  if (-1 != extLoc &&
      extLoc != specLength - 1 &&
      // nothing over 20 chars long can be sanely considered an
      // extension.... Dat dere would be just data.
      specLength - extLoc < 20) 
  {
    return GetTypeFromExtension(Substring(specStr, extLoc + 1), aContentType);
  }

  // We found no information; say so.
  return NS_ERROR_NOT_AVAILABLE;
}

NS_IMETHODIMP nsExternalHelperAppService::GetTypeFromFile(nsIFile* aFile, nsACString& aContentType)
{
  NS_ENSURE_ARG_POINTER(aFile);
  nsresult rv;

  // Get the Extension
  nsAutoString fileName;
  rv = aFile->GetLeafName(fileName);
  if (NS_FAILED(rv)) return rv;
 
  nsAutoCString fileExt;
  if (!fileName.IsEmpty())
  {
    int32_t len = fileName.Length(); 
    for (int32_t i = len; i >= 0; i--) 
    {
      if (fileName[i] == char16_t('.'))
      {
        CopyUTF16toUTF8(fileName.get() + i + 1, fileExt);
        break;
      }
    }
  }

  if (fileExt.IsEmpty())
    return NS_ERROR_FAILURE;

  return GetTypeFromExtension(fileExt, aContentType);
}

nsresult nsExternalHelperAppService::FillMIMEInfoForMimeTypeFromExtras(
  const nsACString& aContentType, nsIMIMEInfo * aMIMEInfo)
{
  NS_ENSURE_ARG( aMIMEInfo );

  NS_ENSURE_ARG( !aContentType.IsEmpty() );

  // Look for default entry with matching mime type.
  nsAutoCString MIMEType(aContentType);
  ToLowerCase(MIMEType);
  int32_t numEntries = ArrayLength(extraMimeEntries);
  for (int32_t index = 0; index < numEntries; index++)
  {
      if ( MIMEType.Equals(extraMimeEntries[index].mMimeType) )
      {
          // This is the one. Set attributes appropriately.
          aMIMEInfo->SetFileExtensions(nsDependentCString(extraMimeEntries[index].mFileExtensions));
          aMIMEInfo->SetDescription(NS_ConvertASCIItoUTF16(extraMimeEntries[index].mDescription));
          return NS_OK;
      }
  }

  return NS_ERROR_NOT_AVAILABLE;
}

nsresult nsExternalHelperAppService::FillMIMEInfoForExtensionFromExtras(
  const nsACString& aExtension, nsIMIMEInfo * aMIMEInfo)
{
  nsAutoCString type;
  bool found = GetTypeFromExtras(aExtension, type);
  if (!found)
    return NS_ERROR_NOT_AVAILABLE;
  return FillMIMEInfoForMimeTypeFromExtras(type, aMIMEInfo);
}

bool nsExternalHelperAppService::GetTypeFromExtras(const nsACString& aExtension, nsACString& aMIMEType)
{
  NS_ASSERTION(!aExtension.IsEmpty(), "Empty aExtension parameter!");

  // Look for default entry with matching extension.
  nsDependentCString::const_iterator start, end, iter;
  int32_t numEntries = ArrayLength(extraMimeEntries);
  for (int32_t index = 0; index < numEntries; index++)
  {
      nsDependentCString extList(extraMimeEntries[index].mFileExtensions);
      extList.BeginReading(start);
      extList.EndReading(end);
      iter = start;
      while (start != end)
      {
          FindCharInReadable(',', iter, end);
          if (Substring(start, iter).Equals(aExtension,
                                            nsCaseInsensitiveCStringComparator()))
          {
              aMIMEType = extraMimeEntries[index].mMimeType;
              return true;
          }
          if (iter != end) {
            ++iter;
          }
          start = iter;
      }
  }

  return false;
}

bool
nsExternalHelperAppService::GetMIMETypeFromOSForExtension(const nsACString& aExtension, nsACString& aMIMEType)
{
  bool found = false;
  nsCOMPtr<nsIMIMEInfo> mimeInfo = GetMIMEInfoFromOS(EmptyCString(), aExtension, &found);
  return found && mimeInfo && NS_SUCCEEDED(mimeInfo->GetMIMEType(aMIMEType));
}