summaryrefslogtreecommitdiffstats
path: root/src/engine/SCons/Node/FS.py
blob: e5b81470d397e691199bd07c0d4c7620b0a122e6 (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
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
"""scons.Node.FS

File system nodes.

These Nodes represent the canonical external objects that people think
of when they think of building software: files and directories.

This holds a "default_fs" variable that should be initialized with an FS
that can be used by scripts or modules looking for the canonical default.

"""

#
# __COPYRIGHT__
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
from __future__ import generators  ### KEEP FOR COMPATIBILITY FIXERS

__revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"

from itertools import izip
import cStringIO
import fnmatch
import os
import os.path
import re
import shutil
import stat
import sys
import time

try:
    import codecs
except ImportError:
    pass
else:
    # TODO(2.2):  Remove when 2.3 becomes the minimal supported version.
    try:
        codecs.BOM_UTF8
    except AttributeError:
        codecs.BOM_UTF8 = '\xef\xbb\xbf'
    try:
        codecs.BOM_UTF16_LE
        codecs.BOM_UTF16_BE
    except AttributeError:
        codecs.BOM_UTF16_LE = '\xff\xfe'
        codecs.BOM_UTF16_BE = '\xfe\xff'

    # Provide a wrapper function to handle decoding differences in
    # different versions of Python.  Normally, we'd try to do this in the
    # compat layer (and maybe it still makes sense to move there?) but
    # that doesn't provide a way to supply the string class used in
    # pre-2.3 Python versions with a .decode() method that all strings
    # naturally have.  Plus, the 2.[01] encodings behave differently
    # enough that we have to settle for a lowest-common-denominator
    # wrapper approach.
    #
    # Note that the 2.[012] implementations below may be inefficient
    # because they perform an explicit look up of the encoding for every
    # decode, but they're old enough (and we want to stop supporting
    # them soon enough) that it's not worth complicating the interface.
    # Think of it as additional incentive for people to upgrade...
    try:
        ''.decode
    except AttributeError:
        # 2.0 through 2.2:  strings have no .decode() method
        try:
            codecs.lookup('ascii').decode
        except AttributeError:
            # 2.0 and 2.1:  encodings are a tuple of functions, and the
            # decode() function returns a (result, length) tuple.
            def my_decode(contents, encoding):
                return codecs.lookup(encoding)[1](contents)[0]
        else:
            # 2.2:  encodings are an object with methods, and the
            # .decode() method returns just the decoded bytes.
            def my_decode(contents, encoding):
                return codecs.lookup(encoding).decode(contents)
    else:
        # 2.3 or later:  use the .decode() string method
        def my_decode(contents, encoding):
            return contents.decode(encoding)

import SCons.Action
from SCons.Debug import logInstanceCreation
import SCons.Errors
import SCons.Memoize
import SCons.Node
import SCons.Node.Alias
import SCons.Subst
import SCons.Util
import SCons.Warnings

from SCons.Debug import Trace

do_store_info = True


class EntryProxyAttributeError(AttributeError):
    """
    An AttributeError subclass for recording and displaying the name
    of the underlying Entry involved in an AttributeError exception.
    """
    def __init__(self, entry_proxy, attribute):
        AttributeError.__init__(self)
        self.entry_proxy = entry_proxy
        self.attribute = attribute
    def __str__(self):
        entry = self.entry_proxy.get()
        fmt = "%s instance %s has no attribute %s"
        return fmt % (entry.__class__.__name__,
                      repr(entry.name),
                      repr(self.attribute))

# The max_drift value:  by default, use a cached signature value for
# any file that's been untouched for more than two days.
default_max_drift = 2*24*60*60

#
# We stringify these file system Nodes a lot.  Turning a file system Node
# into a string is non-trivial, because the final string representation
# can depend on a lot of factors:  whether it's a derived target or not,
# whether it's linked to a repository or source directory, and whether
# there's duplication going on.  The normal technique for optimizing
# calculations like this is to memoize (cache) the string value, so you
# only have to do the calculation once.
#
# A number of the above factors, however, can be set after we've already
# been asked to return a string for a Node, because a Repository() or
# VariantDir() call or the like may not occur until later in SConscript
# files.  So this variable controls whether we bother trying to save
# string values for Nodes.  The wrapper interface can set this whenever
# they're done mucking with Repository and VariantDir and the other stuff,
# to let this module know it can start returning saved string values
# for Nodes.
#
Save_Strings = None

def save_strings(val):
    global Save_Strings
    Save_Strings = val

#
# Avoid unnecessary function calls by recording a Boolean value that
# tells us whether or not os.path.splitdrive() actually does anything
# on this system, and therefore whether we need to bother calling it
# when looking up path names in various methods below.
# 

do_splitdrive = None

def initialize_do_splitdrive():
    global do_splitdrive
    drive, path = os.path.splitdrive('X:/foo')
    do_splitdrive = not not drive

initialize_do_splitdrive()

#

needs_normpath_check = None

def initialize_normpath_check():
    """
    Initialize the normpath_check regular expression.

    This function is used by the unit tests to re-initialize the pattern
    when testing for behavior with different values of os.sep.
    """
    global needs_normpath_check
    if os.sep == '/':
        pattern = r'.*/|\.$|\.\.$'
    else:
        pattern = r'.*[/%s]|\.$|\.\.$' % re.escape(os.sep)
    needs_normpath_check = re.compile(pattern)

initialize_normpath_check()

#
# SCons.Action objects for interacting with the outside world.
#
# The Node.FS methods in this module should use these actions to
# create and/or remove files and directories; they should *not* use
# os.{link,symlink,unlink,mkdir}(), etc., directly.
#
# Using these SCons.Action objects ensures that descriptions of these
# external activities are properly displayed, that the displays are
# suppressed when the -s (silent) option is used, and (most importantly)
# the actions are disabled when the the -n option is used, in which case
# there should be *no* changes to the external file system(s)...
#

if hasattr(os, 'link'):
    def _hardlink_func(fs, src, dst):
        # If the source is a symlink, we can't just hard-link to it
        # because a relative symlink may point somewhere completely
        # different.  We must disambiguate the symlink and then
        # hard-link the final destination file.
        while fs.islink(src):
            link = fs.readlink(src)
            if not os.path.isabs(link):
                src = link
            else:
                src = os.path.join(os.path.dirname(src), link)
        fs.link(src, dst)
else:
    _hardlink_func = None

if hasattr(os, 'symlink'):
    def _softlink_func(fs, src, dst):
        fs.symlink(src, dst)
else:
    _softlink_func = None

def _copy_func(fs, src, dest):
    shutil.copy2(src, dest)
    st = fs.stat(src)
    fs.chmod(dest, stat.S_IMODE(st[stat.ST_MODE]) | stat.S_IWRITE)


Valid_Duplicates = ['hard-soft-copy', 'soft-hard-copy',
                    'hard-copy', 'soft-copy', 'copy']

Link_Funcs = [] # contains the callables of the specified duplication style

def set_duplicate(duplicate):
    # Fill in the Link_Funcs list according to the argument
    # (discarding those not available on the platform).

    # Set up the dictionary that maps the argument names to the
    # underlying implementations.  We do this inside this function,
    # not in the top-level module code, so that we can remap os.link
    # and os.symlink for testing purposes.
    link_dict = {
        'hard' : _hardlink_func,
        'soft' : _softlink_func,
        'copy' : _copy_func
    }

    if not duplicate in Valid_Duplicates:
        raise SCons.Errors.InternalError, ("The argument of set_duplicate "
                                           "should be in Valid_Duplicates")
    global Link_Funcs
    Link_Funcs = []
    for func in duplicate.split('-'):
        if link_dict[func]:
            Link_Funcs.append(link_dict[func])

def LinkFunc(target, source, env):
    # Relative paths cause problems with symbolic links, so
    # we use absolute paths, which may be a problem for people
    # who want to move their soft-linked src-trees around. Those
    # people should use the 'hard-copy' mode, softlinks cannot be
    # used for that; at least I have no idea how ...
    src = source[0].abspath
    dest = target[0].abspath
    dir, file = os.path.split(dest)
    if dir and not target[0].fs.isdir(dir):
        os.makedirs(dir)
    if not Link_Funcs:
        # Set a default order of link functions.
        set_duplicate('hard-soft-copy')
    fs = source[0].fs
    # Now link the files with the previously specified order.
    for func in Link_Funcs:
        try:
            func(fs, src, dest)
            break
        except (IOError, OSError):
            # An OSError indicates something happened like a permissions
            # problem or an attempt to symlink across file-system
            # boundaries.  An IOError indicates something like the file
            # not existing.  In either case, keeping trying additional
            # functions in the list and only raise an error if the last
            # one failed.
            if func == Link_Funcs[-1]:
                # exception of the last link method (copy) are fatal
                raise
    return 0

Link = SCons.Action.Action(LinkFunc, None)
def LocalString(target, source, env):
    return 'Local copy of %s from %s' % (target[0], source[0])

LocalCopy = SCons.Action.Action(LinkFunc, LocalString)

def UnlinkFunc(target, source, env):
    t = target[0]
    t.fs.unlink(t.abspath)
    return 0

Unlink = SCons.Action.Action(UnlinkFunc, None)

def MkdirFunc(target, source, env):
    t = target[0]
    if not t.exists():
        t.fs.mkdir(t.abspath)
    return 0

Mkdir = SCons.Action.Action(MkdirFunc, None, presub=None)

MkdirBuilder = None

def get_MkdirBuilder():
    global MkdirBuilder
    if MkdirBuilder is None:
        import SCons.Builder
        import SCons.Defaults
        # "env" will get filled in by Executor.get_build_env()
        # calling SCons.Defaults.DefaultEnvironment() when necessary.
        MkdirBuilder = SCons.Builder.Builder(action = Mkdir,
                                             env = None,
                                             explain = None,
                                             is_explicit = None,
                                             target_scanner = SCons.Defaults.DirEntryScanner,
                                             name = "MkdirBuilder")
    return MkdirBuilder

class _Null:
    pass

_null = _Null()

DefaultSCCSBuilder = None
DefaultRCSBuilder = None

def get_DefaultSCCSBuilder():
    global DefaultSCCSBuilder
    if DefaultSCCSBuilder is None:
        import SCons.Builder
        # "env" will get filled in by Executor.get_build_env()
        # calling SCons.Defaults.DefaultEnvironment() when necessary.
        act = SCons.Action.Action('$SCCSCOM', '$SCCSCOMSTR')
        DefaultSCCSBuilder = SCons.Builder.Builder(action = act,
                                                   env = None,
                                                   name = "DefaultSCCSBuilder")
    return DefaultSCCSBuilder

def get_DefaultRCSBuilder():
    global DefaultRCSBuilder
    if DefaultRCSBuilder is None:
        import SCons.Builder
        # "env" will get filled in by Executor.get_build_env()
        # calling SCons.Defaults.DefaultEnvironment() when necessary.
        act = SCons.Action.Action('$RCS_COCOM', '$RCS_COCOMSTR')
        DefaultRCSBuilder = SCons.Builder.Builder(action = act,
                                                  env = None,
                                                  name = "DefaultRCSBuilder")
    return DefaultRCSBuilder

# Cygwin's os.path.normcase pretends it's on a case-sensitive filesystem.
_is_cygwin = sys.platform == "cygwin"
if os.path.normcase("TeSt") == os.path.normpath("TeSt") and not _is_cygwin:
    def _my_normcase(x):
        return x
else:
    def _my_normcase(x):
        return x.upper()



class DiskChecker:
    def __init__(self, type, do, ignore):
        self.type = type
        self.do = do
        self.ignore = ignore
        self.set_do()
    def set_do(self):
        self.__call__ = self.do
    def set_ignore(self):
        self.__call__ = self.ignore
    def set(self, list):
        if self.type in list:
            self.set_do()
        else:
            self.set_ignore()

def do_diskcheck_match(node, predicate, errorfmt):
    result = predicate()
    try:
        # If calling the predicate() cached a None value from stat(),
        # remove it so it doesn't interfere with later attempts to
        # build this Node as we walk the DAG.  (This isn't a great way
        # to do this, we're reaching into an interface that doesn't
        # really belong to us, but it's all about performance, so
        # for now we'll just document the dependency...)
        if node._memo['stat'] is None:
            del node._memo['stat']
    except (AttributeError, KeyError):
        pass
    if result:
        raise TypeError, errorfmt % node.abspath

def ignore_diskcheck_match(node, predicate, errorfmt):
    pass

def do_diskcheck_rcs(node, name):
    try:
        rcs_dir = node.rcs_dir
    except AttributeError:
        if node.entry_exists_on_disk('RCS'):
            rcs_dir = node.Dir('RCS')
        else:
            rcs_dir = None
        node.rcs_dir = rcs_dir
    if rcs_dir:
        return rcs_dir.entry_exists_on_disk(name+',v')
    return None

def ignore_diskcheck_rcs(node, name):
    return None

def do_diskcheck_sccs(node, name):
    try:
        sccs_dir = node.sccs_dir
    except AttributeError:
        if node.entry_exists_on_disk('SCCS'):
            sccs_dir = node.Dir('SCCS')
        else:
            sccs_dir = None
        node.sccs_dir = sccs_dir
    if sccs_dir:
        return sccs_dir.entry_exists_on_disk('s.'+name)
    return None

def ignore_diskcheck_sccs(node, name):
    return None

diskcheck_match = DiskChecker('match', do_diskcheck_match, ignore_diskcheck_match)
diskcheck_rcs = DiskChecker('rcs', do_diskcheck_rcs, ignore_diskcheck_rcs)
diskcheck_sccs = DiskChecker('sccs', do_diskcheck_sccs, ignore_diskcheck_sccs)

diskcheckers = [
    diskcheck_match,
    diskcheck_rcs,
    diskcheck_sccs,
]

def set_diskcheck(list):
    for dc in diskcheckers:
        dc.set(list)

def diskcheck_types():
    return [dc.type for dc in diskcheckers]



class EntryProxy(SCons.Util.Proxy):
    def __get_abspath(self):
        entry = self.get()
        return SCons.Subst.SpecialAttrWrapper(entry.get_abspath(),
                                             entry.name + "_abspath")

    def __get_filebase(self):
        name = self.get().name
        return SCons.Subst.SpecialAttrWrapper(SCons.Util.splitext(name)[0],
                                             name + "_filebase")

    def __get_suffix(self):
        name = self.get().name
        return SCons.Subst.SpecialAttrWrapper(SCons.Util.splitext(name)[1],
                                             name + "_suffix")

    def __get_file(self):
        name = self.get().name
        return SCons.Subst.SpecialAttrWrapper(name, name + "_file")

    def __get_base_path(self):
        """Return the file's directory and file name, with the
        suffix stripped."""
        entry = self.get()
        return SCons.Subst.SpecialAttrWrapper(SCons.Util.splitext(entry.get_path())[0],
                                             entry.name + "_base")

    def __get_posix_path(self):
        """Return the path with / as the path separator,
        regardless of platform."""
        if os.sep == '/':
            return self
        else:
            entry = self.get()
            r = entry.get_path().replace(os.sep, '/')
            return SCons.Subst.SpecialAttrWrapper(r, entry.name + "_posix")

    def __get_windows_path(self):
        """Return the path with \ as the path separator,
        regardless of platform."""
        if os.sep == '\\':
            return self
        else:
            entry = self.get()
            r = entry.get_path().replace(os.sep, '\\')
            return SCons.Subst.SpecialAttrWrapper(r, entry.name + "_windows")

    def __get_srcnode(self):
        return EntryProxy(self.get().srcnode())

    def __get_srcdir(self):
        """Returns the directory containing the source node linked to this
        node via VariantDir(), or the directory of this node if not linked."""
        return EntryProxy(self.get().srcnode().dir)

    def __get_rsrcnode(self):
        return EntryProxy(self.get().srcnode().rfile())

    def __get_rsrcdir(self):
        """Returns the directory containing the source node linked to this
        node via VariantDir(), or the directory of this node if not linked."""
        return EntryProxy(self.get().srcnode().rfile().dir)

    def __get_dir(self):
        return EntryProxy(self.get().dir)

    dictSpecialAttrs = { "base"     : __get_base_path,
                         "posix"    : __get_posix_path,
                         "windows"  : __get_windows_path,
                         "win32"    : __get_windows_path,
                         "srcpath"  : __get_srcnode,
                         "srcdir"   : __get_srcdir,
                         "dir"      : __get_dir,
                         "abspath"  : __get_abspath,
                         "filebase" : __get_filebase,
                         "suffix"   : __get_suffix,
                         "file"     : __get_file,
                         "rsrcpath" : __get_rsrcnode,
                         "rsrcdir"  : __get_rsrcdir,
                       }

    def __getattr__(self, name):
        # This is how we implement the "special" attributes
        # such as base, posix, srcdir, etc.
        try:
            attr_function = self.dictSpecialAttrs[name]
        except KeyError:
            try:
                attr = SCons.Util.Proxy.__getattr__(self, name)
            except AttributeError, e:
                # Raise our own AttributeError subclass with an
                # overridden __str__() method that identifies the
                # name of the entry that caused the exception.
                raise EntryProxyAttributeError(self, name)
            return attr
        else:
            return attr_function(self)

class Base(SCons.Node.Node):
    """A generic class for file system entries.  This class is for
    when we don't know yet whether the entry being looked up is a file
    or a directory.  Instances of this class can morph into either
    Dir or File objects by a later, more precise lookup.

    Note: this class does not define __cmp__ and __hash__ for
    efficiency reasons.  SCons does a lot of comparing of
    Node.FS.{Base,Entry,File,Dir} objects, so those operations must be
    as fast as possible, which means we want to use Python's built-in
    object identity comparisons.
    """

    memoizer_counters = []

    def __init__(self, name, directory, fs):
        """Initialize a generic Node.FS.Base object.

        Call the superclass initialization, take care of setting up
        our relative and absolute paths, identify our parent
        directory, and indicate that this node should use
        signatures."""
        if __debug__: logInstanceCreation(self, 'Node.FS.Base')
        SCons.Node.Node.__init__(self)

        # Filenames and paths are probably reused and are intern'ed to
        # save some memory.
        self.name = SCons.Util.silent_intern(name)
        self.suffix = SCons.Util.silent_intern(SCons.Util.splitext(name)[1])
        self.fs = fs

        assert directory, "A directory must be provided"

        self.abspath = SCons.Util.silent_intern(directory.entry_abspath(name))
        self.labspath = SCons.Util.silent_intern(directory.entry_labspath(name))
        if directory.path == '.':
            self.path = SCons.Util.silent_intern(name)
        else:
            self.path = SCons.Util.silent_intern(directory.entry_path(name))
        if directory.tpath == '.':
            self.tpath = SCons.Util.silent_intern(name)
        else:
            self.tpath = SCons.Util.silent_intern(directory.entry_tpath(name))
        self.path_elements = directory.path_elements + [self]

        self.dir = directory
        self.cwd = None # will hold the SConscript directory for target nodes
        self.duplicate = directory.duplicate

    def str_for_display(self):
        return '"' + self.__str__() + '"'

    def must_be_same(self, klass):
        """
        This node, which already existed, is being looked up as the
        specified klass.  Raise an exception if it isn't.
        """
        if isinstance(self, klass) or klass is Entry:
            return
        raise TypeError, "Tried to lookup %s '%s' as a %s." %\
              (self.__class__.__name__, self.path, klass.__name__)

    def get_dir(self):
        return self.dir

    def get_suffix(self):
        return self.suffix

    def rfile(self):
        return self

    def __str__(self):
        """A Node.FS.Base object's string representation is its path
        name."""
        global Save_Strings
        if Save_Strings:
            return self._save_str()
        return self._get_str()

    memoizer_counters.append(SCons.Memoize.CountValue('_save_str'))

    def _save_str(self):
        try:
            return self._memo['_save_str']
        except KeyError:
            pass
        result = intern(self._get_str())
        self._memo['_save_str'] = result
        return result

    def _get_str(self):
        global Save_Strings
        if self.duplicate or self.is_derived():
            return self.get_path()
        srcnode = self.srcnode()
        if srcnode.stat() is None and self.stat() is not None:
            result = self.get_path()
        else:
            result = srcnode.get_path()
        if not Save_Strings:
            # We're not at the point where we're saving the string string
            # representations of FS Nodes (because we haven't finished
            # reading the SConscript files and need to have str() return
            # things relative to them).  That also means we can't yet
            # cache values returned (or not returned) by stat(), since
            # Python code in the SConscript files might still create
            # or otherwise affect the on-disk file.  So get rid of the
            # values that the underlying stat() method saved.
            try: del self._memo['stat']
            except KeyError: pass
            if self is not srcnode:
                try: del srcnode._memo['stat']
                except KeyError: pass
        return result

    rstr = __str__

    memoizer_counters.append(SCons.Memoize.CountValue('stat'))

    def stat(self):
        try: return self._memo['stat']
        except KeyError: pass
        try: result = self.fs.stat(self.abspath)
        except os.error: result = None
        self._memo['stat'] = result
        return result

    def exists(self):
        return self.stat() is not None

    def rexists(self):
        return self.rfile().exists()

    def getmtime(self):
        st = self.stat()
        if st: return st[stat.ST_MTIME]
        else: return None

    def getsize(self):
        st = self.stat()
        if st: return st[stat.ST_SIZE]
        else: return None

    def isdir(self):
        st = self.stat()
        return st is not None and stat.S_ISDIR(st[stat.ST_MODE])

    def isfile(self):
        st = self.stat()
        return st is not None and stat.S_ISREG(st[stat.ST_MODE])

    if hasattr(os, 'symlink'):
        def islink(self):
            try: st = self.fs.lstat(self.abspath)
            except os.error: return 0
            return stat.S_ISLNK(st[stat.ST_MODE])
    else:
        def islink(self):
            return 0                    # no symlinks

    def is_under(self, dir):
        if self is dir:
            return 1
        else:
            return self.dir.is_under(dir)

    def set_local(self):
        self._local = 1

    def srcnode(self):
        """If this node is in a build path, return the node
        corresponding to its source file.  Otherwise, return
        ourself.
        """
        srcdir_list = self.dir.srcdir_list()
        if srcdir_list:
            srcnode = srcdir_list[0].Entry(self.name)
            srcnode.must_be_same(self.__class__)
            return srcnode
        return self

    def get_path(self, dir=None):
        """Return path relative to the current working directory of the
        Node.FS.Base object that owns us."""
        if not dir:
            dir = self.fs.getcwd()
        if self == dir:
            return '.'
        path_elems = self.path_elements
        try: i = path_elems.index(dir)
        except ValueError: pass
        else: path_elems = path_elems[i+1:]
        path_elems = [n.name for n in path_elems]
        return os.sep.join(path_elems)

    def set_src_builder(self, builder):
        """Set the source code builder for this node."""
        self.sbuilder = builder
        if not self.has_builder():
            self.builder_set(builder)

    def src_builder(self):
        """Fetch the source code builder for this node.

        If there isn't one, we cache the source code builder specified
        for the directory (which in turn will cache the value from its
        parent directory, and so on up to the file system root).
        """
        try:
            scb = self.sbuilder
        except AttributeError:
            scb = self.dir.src_builder()
            self.sbuilder = scb
        return scb

    def get_abspath(self):
        """Get the absolute path of the file."""
        return self.abspath

    def for_signature(self):
        # Return just our name.  Even an absolute path would not work,
        # because that can change thanks to symlinks or remapped network
        # paths.
        return self.name

    def get_subst_proxy(self):
        try:
            return self._proxy
        except AttributeError:
            ret = EntryProxy(self)
            self._proxy = ret
            return ret

    def target_from_source(self, prefix, suffix, splitext=SCons.Util.splitext):
        """

        Generates a target entry that corresponds to this entry (usually
        a source file) with the specified prefix and suffix.

        Note that this method can be overridden dynamically for generated
        files that need different behavior.  See Tool/swig.py for
        an example.
        """
        return self.dir.Entry(prefix + splitext(self.name)[0] + suffix)

    def _Rfindalldirs_key(self, pathlist):
        return pathlist

    memoizer_counters.append(SCons.Memoize.CountDict('Rfindalldirs', _Rfindalldirs_key))

    def Rfindalldirs(self, pathlist):
        """
        Return all of the directories for a given path list, including
        corresponding "backing" directories in any repositories.

        The Node lookups are relative to this Node (typically a
        directory), so memoizing result saves cycles from looking
        up the same path for each target in a given directory.
        """
        try:
            memo_dict = self._memo['Rfindalldirs']
        except KeyError:
            memo_dict = {}
            self._memo['Rfindalldirs'] = memo_dict
        else:
            try:
                return memo_dict[pathlist]
            except KeyError:
                pass

        create_dir_relative_to_self = self.Dir
        result = []
        for path in pathlist:
            if isinstance(path, SCons.Node.Node):
                result.append(path)
            else:
                dir = create_dir_relative_to_self(path)
                result.extend(dir.get_all_rdirs())

        memo_dict[pathlist] = result

        return result

    def RDirs(self, pathlist):
        """Search for a list of directories in the Repository list."""
        cwd = self.cwd or self.fs._cwd
        return cwd.Rfindalldirs(pathlist)

    memoizer_counters.append(SCons.Memoize.CountValue('rentry'))

    def rentry(self):
        try:
            return self._memo['rentry']
        except KeyError:
            pass
        result = self
        if not self.exists():
            norm_name = _my_normcase(self.name)
            for dir in self.dir.get_all_rdirs():
                try:
                    node = dir.entries[norm_name]
                except KeyError:
                    if dir.entry_exists_on_disk(self.name):
                        result = dir.Entry(self.name)
                        break
        self._memo['rentry'] = result
        return result

    def _glob1(self, pattern, ondisk=True, source=False, strings=False):
        return []

class Entry(Base):
    """This is the class for generic Node.FS entries--that is, things
    that could be a File or a Dir, but we're just not sure yet.
    Consequently, the methods in this class really exist just to
    transform their associated object into the right class when the
    time comes, and then call the same-named method in the transformed
    class."""

    def diskcheck_match(self):
        pass

    def disambiguate(self, must_exist=None):
        """
        """
        if self.isdir():
            self.__class__ = Dir
            self._morph()
        elif self.isfile():
            self.__class__ = File
            self._morph()
            self.clear()
        else:
            # There was nothing on-disk at this location, so look in
            # the src directory.
            #
            # We can't just use self.srcnode() straight away because
            # that would create an actual Node for this file in the src
            # directory, and there might not be one.  Instead, use the
            # dir_on_disk() method to see if there's something on-disk
            # with that name, in which case we can go ahead and call
            # self.srcnode() to create the right type of entry.
            srcdir = self.dir.srcnode()
            if srcdir != self.dir and \
               srcdir.entry_exists_on_disk(self.name) and \
               self.srcnode().isdir():
                self.__class__ = Dir
                self._morph()
            elif must_exist:
                msg = "No such file or directory: '%s'" % self.abspath
                raise SCons.Errors.UserError, msg
            else:
                self.__class__ = File
                self._morph()
                self.clear()
        return self

    def rfile(self):
        """We're a generic Entry, but the caller is actually looking for
        a File at this point, so morph into one."""
        self.__class__ = File
        self._morph()
        self.clear()
        return File.rfile(self)

    def scanner_key(self):
        return self.get_suffix()

    def get_contents(self):
        """Fetch the contents of the entry.  Returns the exact binary
        contents of the file."""
        try:
            self = self.disambiguate(must_exist=1)
        except SCons.Errors.UserError:
            # There was nothing on disk with which to disambiguate
            # this entry.  Leave it as an Entry, but return a null
            # string so calls to get_contents() in emitters and the
            # like (e.g. in qt.py) don't have to disambiguate by hand
            # or catch the exception.
            return ''
        else:
            return self.get_contents()

    def get_text_contents(self):
        """Fetch the decoded text contents of a Unicode encoded Entry.

        Since this should return the text contents from the file
        system, we check to see into what sort of subclass we should
        morph this Entry."""
        try:
            self = self.disambiguate(must_exist=1)
        except SCons.Errors.UserError:
            # There was nothing on disk with which to disambiguate
            # this entry.  Leave it as an Entry, but return a null
            # string so calls to get_text_contents() in emitters and
            # the like (e.g. in qt.py) don't have to disambiguate by
            # hand or catch the exception.
            return ''
        else:
            return self.get_text_contents()

    def must_be_same(self, klass):
        """Called to make sure a Node is a Dir.  Since we're an
        Entry, we can morph into one."""
        if self.__class__ is not klass:
            self.__class__ = klass
            self._morph()
            self.clear()

    # The following methods can get called before the Taskmaster has
    # had a chance to call disambiguate() directly to see if this Entry
    # should really be a Dir or a File.  We therefore use these to call
    # disambiguate() transparently (from our caller's point of view).
    #
    # Right now, this minimal set of methods has been derived by just
    # looking at some of the methods that will obviously be called early
    # in any of the various Taskmasters' calling sequences, and then
    # empirically figuring out which additional methods are necessary
    # to make various tests pass.

    def exists(self):
        """Return if the Entry exists.  Check the file system to see
        what we should turn into first.  Assume a file if there's no
        directory."""
        return self.disambiguate().exists()

    def rel_path(self, other):
        d = self.disambiguate()
        if d.__class__ is Entry:
            raise "rel_path() could not disambiguate File/Dir"
        return d.rel_path(other)

    def new_ninfo(self):
        return self.disambiguate().new_ninfo()

    def changed_since_last_build(self, target, prev_ni):
        return self.disambiguate().changed_since_last_build(target, prev_ni)

    def _glob1(self, pattern, ondisk=True, source=False, strings=False):
        return self.disambiguate()._glob1(pattern, ondisk, source, strings)

    def get_subst_proxy(self):
        return self.disambiguate().get_subst_proxy()

# This is for later so we can differentiate between Entry the class and Entry
# the method of the FS class.
_classEntry = Entry


class LocalFS:

    if SCons.Memoize.use_memoizer:
        __metaclass__ = SCons.Memoize.Memoized_Metaclass

    # This class implements an abstraction layer for operations involving
    # a local file system.  Essentially, this wraps any function in
    # the os, os.path or shutil modules that we use to actually go do
    # anything with or to the local file system.
    #
    # Note that there's a very good chance we'll refactor this part of
    # the architecture in some way as we really implement the interface(s)
    # for remote file system Nodes.  For example, the right architecture
    # might be to have this be a subclass instead of a base class.
    # Nevertheless, we're using this as a first step in that direction.
    #
    # We're not using chdir() yet because the calling subclass method
    # needs to use os.chdir() directly to avoid recursion.  Will we
    # really need this one?
    #def chdir(self, path):
    #    return os.chdir(path)
    def chmod(self, path, mode):
        return os.chmod(path, mode)
    def copy(self, src, dst):
        return shutil.copy(src, dst)
    def copy2(self, src, dst):
        return shutil.copy2(src, dst)
    def exists(self, path):
        return os.path.exists(path)
    def getmtime(self, path):
        return os.path.getmtime(path)
    def getsize(self, path):
        return os.path.getsize(path)
    def isdir(self, path):
        return os.path.isdir(path)
    def isfile(self, path):
        return os.path.isfile(path)
    def link(self, src, dst):
        return os.link(src, dst)
    def lstat(self, path):
        return os.lstat(path)
    def listdir(self, path):
        return os.listdir(path)
    def makedirs(self, path):
        return os.makedirs(path)
    def mkdir(self, path):
        return os.mkdir(path)
    def rename(self, old, new):
        return os.rename(old, new)
    def stat(self, path):
        return os.stat(path)
    def symlink(self, src, dst):
        return os.symlink(src, dst)
    def open(self, path):
        return open(path)
    def unlink(self, path):
        return os.unlink(path)

    if hasattr(os, 'symlink'):
        def islink(self, path):
            return os.path.islink(path)
    else:
        def islink(self, path):
            return 0                    # no symlinks

    if hasattr(os, 'readlink'):
        def readlink(self, file):
            return os.readlink(file)
    else:
        def readlink(self, file):
            return ''


#class RemoteFS:
#    # Skeleton for the obvious methods we might need from the
#    # abstraction layer for a remote filesystem.
#    def upload(self, local_src, remote_dst):
#        pass
#    def download(self, remote_src, local_dst):
#        pass


class FS(LocalFS):

    memoizer_counters = []

    def __init__(self, path = None):
        """Initialize the Node.FS subsystem.

        The supplied path is the top of the source tree, where we
        expect to find the top-level build file.  If no path is
        supplied, the current directory is the default.

        The path argument must be a valid absolute path.
        """
        if __debug__: logInstanceCreation(self, 'Node.FS')

        self._memo = {}

        self.Root = {}
        self.SConstruct_dir = None
        self.max_drift = default_max_drift

        self.Top = None
        if path is None:
            self.pathTop = os.getcwd()
        else:
            self.pathTop = path
        self.defaultDrive = _my_normcase(os.path.splitdrive(self.pathTop)[0])

        self.Top = self.Dir(self.pathTop)
        self.Top.path = '.'
        self.Top.tpath = '.'
        self._cwd = self.Top

        DirNodeInfo.fs = self
        FileNodeInfo.fs = self
    
    def set_SConstruct_dir(self, dir):
        self.SConstruct_dir = dir

    def get_max_drift(self):
        return self.max_drift

    def set_max_drift(self, max_drift):
        self.max_drift = max_drift

    def getcwd(self):
        return self._cwd

    def chdir(self, dir, change_os_dir=0):
        """Change the current working directory for lookups.
        If change_os_dir is true, we will also change the "real" cwd
        to match.
        """
        curr=self._cwd
        try:
            if dir is not None:
                self._cwd = dir
                if change_os_dir:
                    os.chdir(dir.abspath)
        except OSError:
            self._cwd = curr
            raise

    def get_root(self, drive):
        """
        Returns the root directory for the specified drive, creating
        it if necessary.
        """
        drive = _my_normcase(drive)
        try:
            return self.Root[drive]
        except KeyError:
            root = RootDir(drive, self)
            self.Root[drive] = root
            if not drive:
                self.Root[self.defaultDrive] = root
            elif drive == self.defaultDrive:
                self.Root[''] = root
            return root

    def _lookup(self, p, directory, fsclass, create=1):
        """
        The generic entry point for Node lookup with user-supplied data.

        This translates arbitrary input into a canonical Node.FS object
        of the specified fsclass.  The general approach for strings is
        to turn it into a fully normalized absolute path and then call
        the root directory's lookup_abs() method for the heavy lifting.

        If the path name begins with '#', it is unconditionally
        interpreted relative to the top-level directory of this FS.  '#'
        is treated as a synonym for the top-level SConstruct directory,
        much like '~' is treated as a synonym for the user's home
        directory in a UNIX shell.  So both '#foo' and '#/foo' refer
        to the 'foo' subdirectory underneath the top-level SConstruct
        directory.

        If the path name is relative, then the path is looked up relative
        to the specified directory, or the current directory (self._cwd,
        typically the SConscript directory) if the specified directory
        is None.
        """
        if isinstance(p, Base):
            # It's already a Node.FS object.  Make sure it's the right
            # class and return.
            p.must_be_same(fsclass)
            return p
        # str(p) in case it's something like a proxy object
        p = str(p)

        initial_hash = (p[0:1] == '#')
        if initial_hash:
            # There was an initial '#', so we strip it and override
            # whatever directory they may have specified with the
            # top-level SConstruct directory.
            p = p[1:]
            directory = self.Top

        if directory and not isinstance(directory, Dir):
            directory = self.Dir(directory)

        if do_splitdrive:
            drive, p = os.path.splitdrive(p)
        else:
            drive = ''
        if drive and not p:
            # This causes a naked drive letter to be treated as a synonym
            # for the root directory on that drive.
            p = os.sep
        absolute = os.path.isabs(p)

        needs_normpath = needs_normpath_check.match(p)

        if initial_hash or not absolute:
            # This is a relative lookup, either to the top-level
            # SConstruct directory (because of the initial '#') or to
            # the current directory (the path name is not absolute).
            # Add the string to the appropriate directory lookup path,
            # after which the whole thing gets normalized.
            if not directory:
                directory = self._cwd
            if p:
                p = directory.labspath + '/' + p
            else:
                p = directory.labspath

        if needs_normpath:
            p = os.path.normpath(p)

        if drive or absolute:
            root = self.get_root(drive)
        else:
            if not directory:
                directory = self._cwd
            root = directory.root

        if os.sep != '/':
            p = p.replace(os.sep, '/')
        return root._lookup_abs(p, fsclass, create)

    def Entry(self, name, directory = None, create = 1):
        """Look up or create a generic Entry node with the specified name.
        If the name is a relative path (begins with ./, ../, or a file
        name), then it is looked up relative to the supplied directory
        node, or to the top level directory of the FS (supplied at
        construction time) if no directory is supplied.
        """
        return self._lookup(name, directory, Entry, create)

    def File(self, name, directory = None, create = 1):
        """Look up or create a File node with the specified name.  If
        the name is a relative path (begins with ./, ../, or a file name),
        then it is looked up relative to the supplied directory node,
        or to the top level directory of the FS (supplied at construction
        time) if no directory is supplied.

        This method will raise TypeError if a directory is found at the
        specified path.
        """
        return self._lookup(name, directory, File, create)

    def Dir(self, name, directory = None, create = True):
        """Look up or create a Dir node with the specified name.  If
        the name is a relative path (begins with ./, ../, or a file name),
        then it is looked up relative to the supplied directory node,
        or to the top level directory of the FS (supplied at construction
        time) if no directory is supplied.

        This method will raise TypeError if a normal file is found at the
        specified path.
        """
        return self._lookup(name, directory, Dir, create)

    def VariantDir(self, variant_dir, src_dir, duplicate=1):
        """Link the supplied variant directory to the source directory
        for purposes of building files."""

        if not isinstance(src_dir, SCons.Node.Node):
            src_dir = self.Dir(src_dir)
        if not isinstance(variant_dir, SCons.Node.Node):
            variant_dir = self.Dir(variant_dir)
        if src_dir.is_under(variant_dir):
            raise SCons.Errors.UserError, "Source directory cannot be under variant directory."
        if variant_dir.srcdir:
            if variant_dir.srcdir == src_dir:
                return # We already did this.
            raise SCons.Errors.UserError, "'%s' already has a source directory: '%s'."%(variant_dir, variant_dir.srcdir)
        variant_dir.link(src_dir, duplicate)

    def Repository(self, *dirs):
        """Specify Repository directories to search."""
        for d in dirs:
            if not isinstance(d, SCons.Node.Node):
                d = self.Dir(d)
            self.Top.addRepository(d)

    def variant_dir_target_climb(self, orig, dir, tail):
        """Create targets in corresponding variant directories

        Climb the directory tree, and look up path names
        relative to any linked variant directories we find.

        Even though this loops and walks up the tree, we don't memoize
        the return value because this is really only used to process
        the command-line targets.
        """
        targets = []
        message = None
        fmt = "building associated VariantDir targets: %s"
        start_dir = dir
        while dir:
            for bd in dir.variant_dirs:
                if start_dir.is_under(bd):
                    # If already in the build-dir location, don't reflect
                    return [orig], fmt % str(orig)
                p = os.path.join(bd.path, *tail)
                targets.append(self.Entry(p))
            tail = [dir.name] + tail
            dir = dir.up()
        if targets:
            message = fmt % ' '.join(map(str, targets))
        return targets, message

    def Glob(self, pathname, ondisk=True, source=True, strings=False, cwd=None):
        """
        Globs

        This is mainly a shim layer 
        """
        if cwd is None:
            cwd = self.getcwd()
        return cwd.glob(pathname, ondisk, source, strings)

class DirNodeInfo(SCons.Node.NodeInfoBase):
    # This should get reset by the FS initialization.
    current_version_id = 1

    fs = None

    def str_to_node(self, s):
        top = self.fs.Top
        root = top.root
        if do_splitdrive:
            drive, s = os.path.splitdrive(s)
            if drive:
                root = self.fs.get_root(drive)
        if not os.path.isabs(s):
            s = top.labspath + '/' + s
        return root._lookup_abs(s, Entry)

class DirBuildInfo(SCons.Node.BuildInfoBase):
    current_version_id = 1

glob_magic_check = re.compile('[*?[]')

def has_glob_magic(s):
    return glob_magic_check.search(s) is not None

class Dir(Base):
    """A class for directories in a file system.
    """

    memoizer_counters = []

    NodeInfo = DirNodeInfo
    BuildInfo = DirBuildInfo

    def __init__(self, name, directory, fs):
        if __debug__: logInstanceCreation(self, 'Node.FS.Dir')
        Base.__init__(self, name, directory, fs)
        self._morph()

    def _morph(self):
        """Turn a file system Node (either a freshly initialized directory
        object or a separate Entry object) into a proper directory object.

        Set up this directory's entries and hook it into the file
        system tree.  Specify that directories (this Node) don't use
        signatures for calculating whether they're current.
        """

        self.repositories = []
        self.srcdir = None

        self.entries = {}
        self.entries['.'] = self
        self.entries['..'] = self.dir
        self.cwd = self
        self.searched = 0
        self._sconsign = None
        self.variant_dirs = []
        self.root = self.dir.root

        # Don't just reset the executor, replace its action list,
        # because it might have some pre-or post-actions that need to
        # be preserved.
        self.builder = get_MkdirBuilder()
        self.get_executor().set_action_list(self.builder.action)

    def diskcheck_match(self):
        diskcheck_match(self, self.isfile,
                        "File %s found where directory expected.")

    def __clearRepositoryCache(self, duplicate=None):
        """Called when we change the repository(ies) for a directory.
        This clears any cached information that is invalidated by changing
        the repository."""

        for node in self.entries.values():
            if node != self.dir:
                if node != self and isinstance(node, Dir):
                    node.__clearRepositoryCache(duplicate)
                else:
                    node.clear()
                    try:
                        del node._srcreps
                    except AttributeError:
                        pass
                    if duplicate is not None:
                        node.duplicate=duplicate

    def __resetDuplicate(self, node):
        if node != self:
            node.duplicate = node.get_dir().duplicate

    def Entry(self, name):
        """
        Looks up or creates an entry node named 'name' relative to
        this directory.
        """
        return self.fs.Entry(name, self)

    def Dir(self, name, create=True):
        """
        Looks up or creates a directory node named 'name' relative to
        this directory.
        """
        return self.fs.Dir(name, self, create)

    def File(self, name):
        """
        Looks up or creates a file node named 'name' relative to
        this directory.
        """
        return self.fs.File(name, self)

    def _lookup_rel(self, name, klass, create=1):
        """
        Looks up a *normalized* relative path name, relative to this
        directory.

        This method is intended for use by internal lookups with
        already-normalized path data.  For general-purpose lookups,
        use the Entry(), Dir() and File() methods above.

        This method does *no* input checking and will die or give
        incorrect results if it's passed a non-normalized path name (e.g.,
        a path containing '..'), an absolute path name, a top-relative
        ('#foo') path name, or any kind of object.
        """
        name = self.entry_labspath(name)
        return self.root._lookup_abs(name, klass, create)

    def link(self, srcdir, duplicate):
        """Set this directory as the variant directory for the
        supplied source directory."""
        self.srcdir = srcdir
        self.duplicate = duplicate
        self.__clearRepositoryCache(duplicate)
        srcdir.variant_dirs.append(self)

    def getRepositories(self):
        """Returns a list of repositories for this directory.
        """
        if self.srcdir and not self.duplicate:
            return self.srcdir.get_all_rdirs() + self.repositories
        return self.repositories

    memoizer_counters.append(SCons.Memoize.CountValue('get_all_rdirs'))

    def get_all_rdirs(self):
        try:
            return list(self._memo['get_all_rdirs'])
        except KeyError:
            pass

        result = [self]
        fname = '.'
        dir = self
        while dir:
            for rep in dir.getRepositories():
                result.append(rep.Dir(fname))
            if fname == '.':
                fname = dir.name
            else:
                fname = dir.name + os.sep + fname
            dir = dir.up()

        self._memo['get_all_rdirs'] = list(result)

        return result

    def addRepository(self, dir):
        if dir != self and not dir in self.repositories:
            self.repositories.append(dir)
            dir.tpath = '.'
            self.__clearRepositoryCache()

    def up(self):
        return self.entries['..']

    def _rel_path_key(self, other):
        return str(other)

    memoizer_counters.append(SCons.Memoize.CountDict('rel_path', _rel_path_key))

    def rel_path(self, other):
        """Return a path to "other" relative to this directory.
        """

        # This complicated and expensive method, which constructs relative
        # paths between arbitrary Node.FS objects, is no longer used
        # by SCons itself.  It was introduced to store dependency paths
        # in .sconsign files relative to the target, but that ended up
        # being significantly inefficient.
        #
        # We're continuing to support the method because some SConstruct
        # files out there started using it when it was available, and
        # we're all about backwards compatibility..

        try:
            memo_dict = self._memo['rel_path']
        except KeyError:
            memo_dict = {}
            self._memo['rel_path'] = memo_dict
        else:
            try:
                return memo_dict[other]
            except KeyError:
                pass

        if self is other:
            result = '.'

        elif not other in self.path_elements:
            try:
                other_dir = other.get_dir()
            except AttributeError:
                result = str(other)
            else:
                if other_dir is None:
                    result = other.name
                else:
                    dir_rel_path = self.rel_path(other_dir)
                    if dir_rel_path == '.':
                        result = other.name
                    else:
                        result = dir_rel_path + os.sep + other.name
        else:
            i = self.path_elements.index(other) + 1

            path_elems = ['..'] * (len(self.path_elements) - i) \
                         + [n.name for n in other.path_elements[i:]]
             
            result = os.sep.join(path_elems)

        memo_dict[other] = result

        return result

    def get_env_scanner(self, env, kw={}):
        import SCons.Defaults
        return SCons.Defaults.DirEntryScanner

    def get_target_scanner(self):
        import SCons.Defaults
        return SCons.Defaults.DirEntryScanner

    def get_found_includes(self, env, scanner, path):
        """Return this directory's implicit dependencies.

        We don't bother caching the results because the scan typically
        shouldn't be requested more than once (as opposed to scanning
        .h file contents, which can be requested as many times as the
        files is #included by other files).
        """
        if not scanner:
            return []
        # Clear cached info for this Dir.  If we already visited this
        # directory on our walk down the tree (because we didn't know at
        # that point it was being used as the source for another Node)
        # then we may have calculated build signature before realizing
        # we had to scan the disk.  Now that we have to, though, we need
        # to invalidate the old calculated signature so that any node
        # dependent on our directory structure gets one that includes
        # info about everything on disk.
        self.clear()
        return scanner(self, env, path)

    #
    # Taskmaster interface subsystem
    #

    def prepare(self):
        pass

    def build(self, **kw):
        """A null "builder" for directories."""
        global MkdirBuilder
        if self.builder is not MkdirBuilder:
            SCons.Node.Node.build(self, **kw)

    #
    #
    #

    def _create(self):
        """Create this directory, silently and without worrying about
        whether the builder is the default or not."""
        listDirs = []
        parent = self
        while parent:
            if parent.exists():
                break
            listDirs.append(parent)
            p = parent.up()
            if p is None:
                # Don't use while: - else: for this condition because
                # if so, then parent is None and has no .path attribute.
                raise SCons.Errors.StopError, parent.path
            parent = p
        listDirs.reverse()
        for dirnode in listDirs:
            try:
                # Don't call dirnode.build(), call the base Node method
                # directly because we definitely *must* create this
                # directory.  The dirnode.build() method will suppress
                # the build if it's the default builder.
                SCons.Node.Node.build(dirnode)
                dirnode.get_executor().nullify()
                # The build() action may or may not have actually
                # created the directory, depending on whether the -n
                # option was used or not.  Delete the _exists and
                # _rexists attributes so they can be reevaluated.
                dirnode.clear()
            except OSError:
                pass

    def multiple_side_effect_has_builder(self):
        global MkdirBuilder
        return self.builder is not MkdirBuilder and self.has_builder()

    def alter_targets(self):
        """Return any corresponding targets in a variant directory.
        """
        return self.fs.variant_dir_target_climb(self, self, [])

    def scanner_key(self):
        """A directory does not get scanned."""
        return None

    def get_text_contents(self):
        """We already emit things in text, so just return the binary
        version."""
        return self.get_contents()

    def get_contents(self):
        """Return content signatures and names of all our children
        separated by new-lines. Ensure that the nodes are sorted."""
        contents = []
        for node in sorted(self.children(), key=lambda t: t.name):
            contents.append('%s %s\n' % (node.get_csig(), node.name))
        return ''.join(contents)

    def get_csig(self):
        """Compute the content signature for Directory nodes. In
        general, this is not needed and the content signature is not
        stored in the DirNodeInfo. However, if get_contents on a Dir
        node is called which has a child directory, the child
        directory should return the hash of its contents."""
        contents = self.get_contents()
        return SCons.Util.MD5signature(contents)

    def do_duplicate(self, src):
        pass

    changed_since_last_build = SCons.Node.Node.state_has_changed

    def is_up_to_date(self):
        """If any child is not up-to-date, then this directory isn't,
        either."""
        if self.builder is not MkdirBuilder and not self.exists():
            return 0
        up_to_date = SCons.Node.up_to_date
        for kid in self.children():
            if kid.get_state() > up_to_date:
                return 0
        return 1

    def rdir(self):
        if not self.exists():
            norm_name = _my_normcase(self.name)
            for dir in self.dir.get_all_rdirs():
                try: node = dir.entries[norm_name]
                except KeyError: node = dir.dir_on_disk(self.name)
                if node and node.exists() and \
                    (isinstance(dir, Dir) or isinstance(dir, Entry)):
                        return node
        return self

    def sconsign(self):
        """Return the .sconsign file info for this directory,
        creating it first if necessary."""
        if not self._sconsign:
            import SCons.SConsign
            self._sconsign = SCons.SConsign.ForDirectory(self)
        return self._sconsign

    def srcnode(self):
        """Dir has a special need for srcnode()...if we
        have a srcdir attribute set, then that *is* our srcnode."""
        if self.srcdir:
            return self.srcdir
        return Base.srcnode(self)

    def get_timestamp(self):
        """Return the latest timestamp from among our children"""
        stamp = 0
        for kid in self.children():
            if kid.get_timestamp() > stamp:
                stamp = kid.get_timestamp()
        return stamp

    def entry_abspath(self, name):
        return self.abspath + os.sep + name

    def entry_labspath(self, name):
        return self.labspath + '/' + name

    def entry_path(self, name):
        return self.path + os.sep + name

    def entry_tpath(self, name):
        return self.tpath + os.sep + name

    def entry_exists_on_disk(self, name):
        try:
            d = self.on_disk_entries
        except AttributeError:
            d = {}
            try:
                entries = os.listdir(self.abspath)
            except OSError:
                pass
            else:
                for entry in map(_my_normcase, entries):
                    d[entry] = True
            self.on_disk_entries = d
        if sys.platform == 'win32':
            name = _my_normcase(name)
            result = d.get(name)
            if result is None:
                # Belt-and-suspenders for Windows:  check directly for
                # 8.3 file names that don't show up in os.listdir().
                result = os.path.exists(self.abspath + os.sep + name)
                d[name] = result
            return result
        else:
            return name in d

    memoizer_counters.append(SCons.Memoize.CountValue('srcdir_list'))

    def srcdir_list(self):
        try:
            return self._memo['srcdir_list']
        except KeyError:
            pass

        result = []

        dirname = '.'
        dir = self
        while dir:
            if dir.srcdir:
                result.append(dir.srcdir.Dir(dirname))
            dirname = dir.name + os.sep + dirname
            dir = dir.up()

        self._memo['srcdir_list'] = result

        return result

    def srcdir_duplicate(self, name):
        for dir in self.srcdir_list():
            if self.is_under(dir):
                # We shouldn't source from something in the build path;
                # variant_dir is probably under src_dir, in which case
                # we are reflecting.
                break
            if dir.entry_exists_on_disk(name):
                srcnode = dir.Entry(name).disambiguate()
                if self.duplicate:
                    node = self.Entry(name).disambiguate()
                    node.do_duplicate(srcnode)
                    return node
                else:
                    return srcnode
        return None

    def _srcdir_find_file_key(self, filename):
        return filename

    memoizer_counters.append(SCons.Memoize.CountDict('srcdir_find_file', _srcdir_find_file_key))

    def srcdir_find_file(self, filename):
        try:
            memo_dict = self._memo['srcdir_find_file']
        except KeyError:
            memo_dict = {}
            self._memo['srcdir_find_file'] = memo_dict
        else:
            try:
                return memo_dict[filename]
            except KeyError:
                pass

        def func(node):
            if (isinstance(node, File) or isinstance(node, Entry)) and \
               (node.is_derived() or node.exists()):
                    return node
            return None

        norm_name = _my_normcase(filename)

        for rdir in self.get_all_rdirs():
            try: node = rdir.entries[norm_name]
            except KeyError: node = rdir.file_on_disk(filename)
            else: node = func(node)
            if node:
                result = (node, self)
                memo_dict[filename] = result
                return result

        for srcdir in self.srcdir_list():
            for rdir in srcdir.get_all_rdirs():
                try: node = rdir.entries[norm_name]
                except KeyError: node = rdir.file_on_disk(filename)
                else: node = func(node)
                if node:
                    result = (File(filename, self, self.fs), srcdir)
                    memo_dict[filename] = result
                    return result

        result = (None, None)
        memo_dict[filename] = result
        return result

    def dir_on_disk(self, name):
        if self.entry_exists_on_disk(name):
            try: return self.Dir(name)
            except TypeError: pass
        node = self.srcdir_duplicate(name)
        if isinstance(node, File):
            return None
        return node

    def file_on_disk(self, name):
        if self.entry_exists_on_disk(name) or \
           diskcheck_rcs(self, name) or \
           diskcheck_sccs(self, name):
            try: return self.File(name)
            except TypeError: pass
        node = self.srcdir_duplicate(name)
        if isinstance(node, Dir):
            return None
        return node

    def walk(self, func, arg):
        """
        Walk this directory tree by calling the specified function
        for each directory in the tree.

        This behaves like the os.path.walk() function, but for in-memory
        Node.FS.Dir objects.  The function takes the same arguments as
        the functions passed to os.path.walk():

                func(arg, dirname, fnames)

        Except that "dirname" will actually be the directory *Node*,
        not the string.  The '.' and '..' entries are excluded from
        fnames.  The fnames list may be modified in-place to filter the
        subdirectories visited or otherwise impose a specific order.
        The "arg" argument is always passed to func() and may be used
        in any way (or ignored, passing None is common).
        """
        entries = self.entries
        names = entries.keys()
        names.remove('.')
        names.remove('..')
        func(arg, self, names)
        for dirname in [n for n in names if isinstance(entries[n], Dir)]:
            entries[dirname].walk(func, arg)

    def glob(self, pathname, ondisk=True, source=False, strings=False):
        """
        Returns a list of Nodes (or strings) matching a specified
        pathname pattern.

        Pathname patterns follow UNIX shell semantics:  * matches
        any-length strings of any characters, ? matches any character,
        and [] can enclose lists or ranges of characters.  Matches do
        not span directory separators.

        The matches take into account Repositories, returning local
        Nodes if a corresponding entry exists in a Repository (either
        an in-memory Node or something on disk).

        By defafult, the glob() function matches entries that exist
        on-disk, in addition to in-memory Nodes.  Setting the "ondisk"
        argument to False (or some other non-true value) causes the glob()
        function to only match in-memory Nodes.  The default behavior is
        to return both the on-disk and in-memory Nodes.

        The "source" argument, when true, specifies that corresponding
        source Nodes must be returned if you're globbing in a build
        directory (initialized with VariantDir()).  The default behavior
        is to return Nodes local to the VariantDir().

        The "strings" argument, when true, returns the matches as strings,
        not Nodes.  The strings are path names relative to this directory.

        The underlying algorithm is adapted from the glob.glob() function
        in the Python library (but heavily modified), and uses fnmatch()
        under the covers.
        """
        dirname, basename = os.path.split(pathname)
        if not dirname:
            return sorted(self._glob1(basename, ondisk, source, strings),
                          key=lambda t: str(t))
        if has_glob_magic(dirname):
            list = self.glob(dirname, ondisk, source, strings=False)
        else:
            list = [self.Dir(dirname, create=True)]
        result = []
        for dir in list:
            r = dir._glob1(basename, ondisk, source, strings)
            if strings:
                r = [os.path.join(str(dir), x) for x in r]
            result.extend(r)
        result.sort(lambda a, b: cmp(str(a), str(b)))
        return result

    def _glob1(self, pattern, ondisk=True, source=False, strings=False):
        """
        Globs for and returns a list of entry names matching a single
        pattern in this directory.

        This searches any repositories and source directories for
        corresponding entries and returns a Node (or string) relative
        to the current directory if an entry is found anywhere.

        TODO: handle pattern with no wildcard
        """
        search_dir_list = self.get_all_rdirs()
        for srcdir in self.srcdir_list():
            search_dir_list.extend(srcdir.get_all_rdirs())

        selfEntry = self.Entry
        names = []
        for dir in search_dir_list:
            # We use the .name attribute from the Node because the keys of
            # the dir.entries dictionary are normalized (that is, all upper
            # case) on case-insensitive systems like Windows.
            node_names = [ v.name for k, v in dir.entries.items()
                           if k not in ('.', '..') ]
            names.extend(node_names)
            if not strings:
                # Make sure the working directory (self) actually has
                # entries for all Nodes in repositories or variant dirs.
                for name in node_names: selfEntry(name)
            if ondisk:
                try:
                    disk_names = os.listdir(dir.abspath)
                except os.error:
                    continue
                names.extend(disk_names)
                if not strings:
                    # We're going to return corresponding Nodes in
                    # the local directory, so we need to make sure
                    # those Nodes exist.  We only want to create
                    # Nodes for the entries that will match the
                    # specified pattern, though, which means we
                    # need to filter the list here, even though
                    # the overall list will also be filtered later,
                    # after we exit this loop.
                    if pattern[0] != '.':
                        #disk_names = [ d for d in disk_names if d[0] != '.' ]
                        disk_names = [x for x in disk_names if x[0] != '.']
                    disk_names = fnmatch.filter(disk_names, pattern)
                    dirEntry = dir.Entry
                    for name in disk_names:
                        # Add './' before disk filename so that '#' at
                        # beginning of filename isn't interpreted.
                        name = './' + name
                        node = dirEntry(name).disambiguate()
                        n = selfEntry(name)
                        if n.__class__ != node.__class__:
                            n.__class__ = node.__class__
                            n._morph()

        names = set(names)
        if pattern[0] != '.':
            #names = [ n for n in names if n[0] != '.' ]
            names = [x for x in names if x[0] != '.']
        names = fnmatch.filter(names, pattern)

        if strings:
            return names

        #return [ self.entries[_my_normcase(n)] for n in names ]
        return [self.entries[_my_normcase(n)] for n in names]

class RootDir(Dir):
    """A class for the root directory of a file system.

    This is the same as a Dir class, except that the path separator
    ('/' or '\\') is actually part of the name, so we don't need to
    add a separator when creating the path names of entries within
    this directory.
    """
    def __init__(self, name, fs):
        if __debug__: logInstanceCreation(self, 'Node.FS.RootDir')
        # We're going to be our own parent directory (".." entry and .dir
        # attribute) so we have to set up some values so Base.__init__()
        # won't gag won't it calls some of our methods.
        self.abspath = ''
        self.labspath = ''
        self.path = ''
        self.tpath = ''
        self.path_elements = []
        self.duplicate = 0
        self.root = self
        Base.__init__(self, name, self, fs)

        # Now set our paths to what we really want them to be: the
        # initial drive letter (the name) plus the directory separator,
        # except for the "lookup abspath," which does not have the
        # drive letter.
        self.abspath = name + os.sep
        self.labspath = ''
        self.path = name + os.sep
        self.tpath = name + os.sep
        self._morph()

        self._lookupDict = {}

        # The // and os.sep + os.sep entries are necessary because
        # os.path.normpath() seems to preserve double slashes at the
        # beginning of a path (presumably for UNC path names), but
        # collapses triple slashes to a single slash.
        self._lookupDict[''] = self
        self._lookupDict['/'] = self
        self._lookupDict['//'] = self
        self._lookupDict[os.sep] = self
        self._lookupDict[os.sep + os.sep] = self

    def must_be_same(self, klass):
        if klass is Dir:
            return
        Base.must_be_same(self, klass)

    def _lookup_abs(self, p, klass, create=1):
        """
        Fast (?) lookup of a *normalized* absolute path.

        This method is intended for use by internal lookups with
        already-normalized path data.  For general-purpose lookups,
        use the FS.Entry(), FS.Dir() or FS.File() methods.

        The caller is responsible for making sure we're passed a
        normalized absolute path; we merely let Python's dictionary look
        up and return the One True Node.FS object for the path.

        If no Node for the specified "p" doesn't already exist, and
        "create" is specified, the Node may be created after recursive
        invocation to find or create the parent directory or directories.
        """
        k = _my_normcase(p)
        try:
            result = self._lookupDict[k]
        except KeyError:
            if not create:
                msg = "No such file or directory: '%s' in '%s' (and create is False)" % (p, str(self))
                raise SCons.Errors.UserError, msg
            # There is no Node for this path name, and we're allowed
            # to create it.
            dir_name, file_name = os.path.split(p)
            dir_node = self._lookup_abs(dir_name, Dir)
            result = klass(file_name, dir_node, self.fs)

            # Double-check on disk (as configured) that the Node we
            # created matches whatever is out there in the real world.
            result.diskcheck_match()

            self._lookupDict[k] = result
            dir_node.entries[_my_normcase(file_name)] = result
            dir_node.implicit = None
        else:
            # There is already a Node for this path name.  Allow it to
            # complain if we were looking for an inappropriate type.
            result.must_be_same(klass)
        return result

    def __str__(self):
        return self.abspath

    def entry_abspath(self, name):
        return self.abspath + name

    def entry_labspath(self, name):
        return '/' + name

    def entry_path(self, name):
        return self.path + name

    def entry_tpath(self, name):
        return self.tpath + name

    def is_under(self, dir):
        if self is dir:
            return 1
        else:
            return 0

    def up(self):
        return None

    def get_dir(self):
        return None

    def src_builder(self):
        return _null

class FileNodeInfo(SCons.Node.NodeInfoBase):
    current_version_id = 1

    field_list = ['csig', 'timestamp', 'size']

    # This should get reset by the FS initialization.
    fs = None

    def str_to_node(self, s):
        top = self.fs.Top
        root = top.root
        if do_splitdrive:
            drive, s = os.path.splitdrive(s)
            if drive:
                root = self.fs.get_root(drive)
        if not os.path.isabs(s):
            s = top.labspath + '/' + s
        return root._lookup_abs(s, Entry)

class FileBuildInfo(SCons.Node.BuildInfoBase):
    current_version_id = 1

    def convert_to_sconsign(self):
        """
        Converts this FileBuildInfo object for writing to a .sconsign file

        This replaces each Node in our various dependency lists with its
        usual string representation: relative to the top-level SConstruct
        directory, or an absolute path if it's outside.
        """
        if os.sep == '/':
            node_to_str = str
        else:
            def node_to_str(n):
                try:
                    s = n.path
                except AttributeError:
                    s = str(n)
                else:
                    s = s.replace(os.sep, '/')
                return s
        for attr in ['bsources', 'bdepends', 'bimplicit']:
            try:
                val = getattr(self, attr)
            except AttributeError:
                pass
            else:
                setattr(self, attr, list(map(node_to_str, val)))
    def convert_from_sconsign(self, dir, name):
        """
        Converts a newly-read FileBuildInfo object for in-SCons use

        For normal up-to-date checking, we don't have any conversion to
        perform--but we're leaving this method here to make that clear.
        """
        pass
    def prepare_dependencies(self):
        """
        Prepares a FileBuildInfo object for explaining what changed

        The bsources, bdepends and bimplicit lists have all been
        stored on disk as paths relative to the top-level SConstruct
        directory.  Convert the strings to actual Nodes (for use by the
        --debug=explain code and --implicit-cache).
        """
        attrs = [
            ('bsources', 'bsourcesigs'),
            ('bdepends', 'bdependsigs'),
            ('bimplicit', 'bimplicitsigs'),
        ]
        for (nattr, sattr) in attrs:
            try:
                strings = getattr(self, nattr)
                nodeinfos = getattr(self, sattr)
            except AttributeError:
                continue
            nodes = []
            for s, ni in izip(strings, nodeinfos):
                if not isinstance(s, SCons.Node.Node):
                    s = ni.str_to_node(s)
                nodes.append(s)
            setattr(self, nattr, nodes)
    def format(self, names=0):
        result = []
        bkids = self.bsources + self.bdepends + self.bimplicit
        bkidsigs = self.bsourcesigs + self.bdependsigs + self.bimplicitsigs
        for bkid, bkidsig in izip(bkids, bkidsigs):
            result.append(str(bkid) + ': ' +
                          ' '.join(bkidsig.format(names=names)))
        result.append('%s [%s]' % (self.bactsig, self.bact))
        return '\n'.join(result)

class File(Base):
    """A class for files in a file system.
    """

    memoizer_counters = []

    NodeInfo = FileNodeInfo
    BuildInfo = FileBuildInfo

    md5_chunksize = 64

    def diskcheck_match(self):
        diskcheck_match(self, self.isdir,
                        "Directory %s found where file expected.")

    def __init__(self, name, directory, fs):
        if __debug__: logInstanceCreation(self, 'Node.FS.File')
        Base.__init__(self, name, directory, fs)
        self._morph()

    def Entry(self, name):
        """Create an entry node named 'name' relative to
        the directory of this file."""
        return self.dir.Entry(name)

    def Dir(self, name, create=True):
        """Create a directory node named 'name' relative to
        the directory of this file."""
        return self.dir.Dir(name, create=create)

    def Dirs(self, pathlist):
        """Create a list of directories relative to the SConscript
        directory of this file."""
        # TODO(1.5)
        # return [self.Dir(p) for p in pathlist]
        return [self.Dir(p) for p in pathlist]

    def File(self, name):
        """Create a file node named 'name' relative to
        the directory of this file."""
        return self.dir.File(name)

    #def generate_build_dict(self):
    #    """Return an appropriate dictionary of values for building
    #    this File."""
    #    return {'Dir' : self.Dir,
    #            'File' : self.File,
    #            'RDirs' : self.RDirs}

    def _morph(self):
        """Turn a file system node into a File object."""
        self.scanner_paths = {}
        if not hasattr(self, '_local'):
            self._local = 0

        # If there was already a Builder set on this entry, then
        # we need to make sure we call the target-decider function,
        # not the source-decider.  Reaching in and doing this by hand
        # is a little bogus.  We'd prefer to handle this by adding
        # an Entry.builder_set() method that disambiguates like the
        # other methods, but that starts running into problems with the
        # fragile way we initialize Dir Nodes with their Mkdir builders,
        # yet still allow them to be overridden by the user.  Since it's
        # not clear right now how to fix that, stick with what works
        # until it becomes clear...
        if self.has_builder():
            self.changed_since_last_build = self.decide_target

    def scanner_key(self):
        return self.get_suffix()

    def get_contents(self):
        if not self.rexists():
            return ''
        fname = self.rfile().abspath
        try:
            contents = open(fname, "rb").read()
        except EnvironmentError, e:
            if not e.filename:
                e.filename = fname
            raise
        return contents

    try:
        import codecs
    except ImportError:
        get_text_contents = get_contents
    else:
        # This attempts to figure out what the encoding of the text is
        # based upon the BOM bytes, and then decodes the contents so that
        # it's a valid python string.
        def get_text_contents(self):
            contents = self.get_contents()
            # The behavior of various decode() methods and functions
            # w.r.t. the initial BOM bytes is different for different
            # encodings and/or Python versions.  ('utf-8' does not strip
            # them, but has a 'utf-8-sig' which does; 'utf-16' seems to
            # strip them; etc.)  Just side step all the complication by
            # explicitly stripping the BOM before we decode().
            if contents.startswith(codecs.BOM_UTF8):
                contents = contents[len(codecs.BOM_UTF8):]
                # TODO(2.2):  Remove when 2.3 becomes floor.
                #contents = contents.decode('utf-8')
                contents = my_decode(contents, 'utf-8')
            elif contents.startswith(codecs.BOM_UTF16_LE):
                contents = contents[len(codecs.BOM_UTF16_LE):]
                # TODO(2.2):  Remove when 2.3 becomes floor.
                #contents = contents.decode('utf-16-le')
                contents = my_decode(contents, 'utf-16-le')
            elif contents.startswith(codecs.BOM_UTF16_BE):
                contents = contents[len(codecs.BOM_UTF16_BE):]
                # TODO(2.2):  Remove when 2.3 becomes floor.
                #contents = contents.decode('utf-16-be')
                contents = my_decode(contents, 'utf-16-be')
            return contents

    def get_content_hash(self):
        """
        Compute and return the MD5 hash for this file.
        """
        if not self.rexists():
            return SCons.Util.MD5signature('')
        fname = self.rfile().abspath
        try:
            cs = SCons.Util.MD5filesignature(fname,
                chunksize=SCons.Node.FS.File.md5_chunksize*1024)
        except EnvironmentError, e:
            if not e.filename:
                e.filename = fname
            raise
        return cs
        

    memoizer_counters.append(SCons.Memoize.CountValue('get_size'))

    def get_size(self):
        try:
            return self._memo['get_size']
        except KeyError:
            pass

        if self.rexists():
            size = self.rfile().getsize()
        else:
            size = 0

        self._memo['get_size'] = size

        return size

    memoizer_counters.append(SCons.Memoize.CountValue('get_timestamp'))

    def get_timestamp(self):
        try:
            return self._memo['get_timestamp']
        except KeyError:
            pass

        if self.rexists():
            timestamp = self.rfile().getmtime()
        else:
            timestamp = 0

        self._memo['get_timestamp'] = timestamp

        return timestamp

    def store_info(self):
        # Merge our build information into the already-stored entry.
        # This accomodates "chained builds" where a file that's a target
        # in one build (SConstruct file) is a source in a different build.
        # See test/chained-build.py for the use case.
        if do_store_info:
            self.dir.sconsign().store_info(self.name, self)

    convert_copy_attrs = [
        'bsources',
        'bimplicit',
        'bdepends',
        'bact',
        'bactsig',
        'ninfo',
    ]


    convert_sig_attrs = [
        'bsourcesigs',
        'bimplicitsigs',
        'bdependsigs',
    ]

    def convert_old_entry(self, old_entry):
        # Convert a .sconsign entry from before the Big Signature
        # Refactoring, doing what we can to convert its information
        # to the new .sconsign entry format.
        #
        # The old format looked essentially like this:
        #
        #   BuildInfo
        #       .ninfo (NodeInfo)
        #           .bsig
        #           .csig
        #           .timestamp
        #           .size
        #       .bsources
        #       .bsourcesigs ("signature" list)
        #       .bdepends
        #       .bdependsigs ("signature" list)
        #       .bimplicit
        #       .bimplicitsigs ("signature" list)
        #       .bact
        #       .bactsig
        #
        # The new format looks like this:
        #
        #   .ninfo (NodeInfo)
        #       .bsig
        #       .csig
        #       .timestamp
        #       .size
        #   .binfo (BuildInfo)
        #       .bsources
        #       .bsourcesigs (NodeInfo list)
        #           .bsig
        #           .csig
        #           .timestamp
        #           .size
        #       .bdepends
        #       .bdependsigs (NodeInfo list)
        #           .bsig
        #           .csig
        #           .timestamp
        #           .size
        #       .bimplicit
        #       .bimplicitsigs (NodeInfo list)
        #           .bsig
        #           .csig
        #           .timestamp
        #           .size
        #       .bact
        #       .bactsig
        #
        # The basic idea of the new structure is that a NodeInfo always
        # holds all available information about the state of a given Node
        # at a certain point in time.  The various .b*sigs lists can just
        # be a list of pointers to the .ninfo attributes of the different
        # dependent nodes, without any copying of information until it's
        # time to pickle it for writing out to a .sconsign file.
        #
        # The complicating issue is that the *old* format only stored one
        # "signature" per dependency, based on however the *last* build
        # was configured.  We don't know from just looking at it whether
        # it was a build signature, a content signature, or a timestamp
        # "signature".  Since we no longer use build signatures, the
        # best we can do is look at the length and if it's thirty two,
        # assume that it was (or might have been) a content signature.
        # If it was actually a build signature, then it will cause a
        # rebuild anyway when it doesn't match the new content signature,
        # but that's probably the best we can do.
        import SCons.SConsign
        new_entry = SCons.SConsign.SConsignEntry()
        new_entry.binfo = self.new_binfo()
        binfo = new_entry.binfo
        for attr in self.convert_copy_attrs:
            try:
                value = getattr(old_entry, attr)
            except AttributeError:
                continue
            setattr(binfo, attr, value)
            delattr(old_entry, attr)
        for attr in self.convert_sig_attrs:
            try:
                sig_list = getattr(old_entry, attr)
            except AttributeError:
                continue
            value = []
            for sig in sig_list:
                ninfo = self.new_ninfo()
                if len(sig) == 32:
                    ninfo.csig = sig
                else:
                    ninfo.timestamp = sig
                value.append(ninfo)
            setattr(binfo, attr, value)
            delattr(old_entry, attr)
        return new_entry

    memoizer_counters.append(SCons.Memoize.CountValue('get_stored_info'))

    def get_stored_info(self):
        try:
            return self._memo['get_stored_info']
        except KeyError:
            pass

        try:
            sconsign_entry = self.dir.sconsign().get_entry(self.name)
        except (KeyError, EnvironmentError):
            import SCons.SConsign
            sconsign_entry = SCons.SConsign.SConsignEntry()
            sconsign_entry.binfo = self.new_binfo()
            sconsign_entry.ninfo = self.new_ninfo()
        else:
            if isinstance(sconsign_entry, FileBuildInfo):
                # This is a .sconsign file from before the Big Signature
                # Refactoring; convert it as best we can.
                sconsign_entry = self.convert_old_entry(sconsign_entry)
            try:
                delattr(sconsign_entry.ninfo, 'bsig')
            except AttributeError:
                pass

        self._memo['get_stored_info'] = sconsign_entry

        return sconsign_entry

    def get_stored_implicit(self):
        binfo = self.get_stored_info().binfo
        binfo.prepare_dependencies()
        try: return binfo.bimplicit
        except AttributeError: return None

    def rel_path(self, other):
        return self.dir.rel_path(other)

    def _get_found_includes_key(self, env, scanner, path):
        return (id(env), id(scanner), path)

    memoizer_counters.append(SCons.Memoize.CountDict('get_found_includes', _get_found_includes_key))

    def get_found_includes(self, env, scanner, path):
        """Return the included implicit dependencies in this file.
        Cache results so we only scan the file once per path
        regardless of how many times this information is requested.
        """
        memo_key = (id(env), id(scanner), path)
        try:
            memo_dict = self._memo['get_found_includes']
        except KeyError:
            memo_dict = {}
            self._memo['get_found_includes'] = memo_dict
        else:
            try:
                return memo_dict[memo_key]
            except KeyError:
                pass

        if scanner:
            # result = [n.disambiguate() for n in scanner(self, env, path)]
            result = scanner(self, env, path)
            result = [N.disambiguate() for N in result]
        else:
            result = []

        memo_dict[memo_key] = result

        return result

    def _createDir(self):
        # ensure that the directories for this node are
        # created.
        self.dir._create()

    def push_to_cache(self):
        """Try to push the node into a cache
        """
        # This should get called before the Nodes' .built() method is
        # called, which would clear the build signature if the file has
        # a source scanner.
        #
        # We have to clear the local memoized values *before* we push
        # the node to cache so that the memoization of the self.exists()
        # return value doesn't interfere.
        if self.nocache:
            return
        self.clear_memoized_values()
        if self.exists():
            self.get_build_env().get_CacheDir().push(self)

    def retrieve_from_cache(self):
        """Try to retrieve the node's content from a cache

        This method is called from multiple threads in a parallel build,
        so only do thread safe stuff here. Do thread unsafe stuff in
        built().

        Returns true iff the node was successfully retrieved.
        """
        if self.nocache:
            return None
        if not self.is_derived():
            return None
        return self.get_build_env().get_CacheDir().retrieve(self)

    def visited(self):
        if self.exists():
            self.get_build_env().get_CacheDir().push_if_forced(self)

        ninfo = self.get_ninfo()

        csig = self.get_max_drift_csig()
        if csig:
            ninfo.csig = csig

        ninfo.timestamp = self.get_timestamp()
        ninfo.size      = self.get_size()

        if not self.has_builder():
            # This is a source file, but it might have been a target file
            # in another build that included more of the DAG.  Copy
            # any build information that's stored in the .sconsign file
            # into our binfo object so it doesn't get lost.
            old = self.get_stored_info()
            self.get_binfo().__dict__.update(old.binfo.__dict__)

        self.store_info()

    def find_src_builder(self):
        if self.rexists():
            return None
        scb = self.dir.src_builder()
        if scb is _null:
            if diskcheck_sccs(self.dir, self.name):
                scb = get_DefaultSCCSBuilder()
            elif diskcheck_rcs(self.dir, self.name):
                scb = get_DefaultRCSBuilder()
            else:
                scb = None
        if scb is not None:
            try:
                b = self.builder
            except AttributeError:
                b = None
            if b is None:
                self.builder_set(scb)
        return scb

    def has_src_builder(self):
        """Return whether this Node has a source builder or not.

        If this Node doesn't have an explicit source code builder, this
        is where we figure out, on the fly, if there's a transparent
        source code builder for it.

        Note that if we found a source builder, we also set the
        self.builder attribute, so that all of the methods that actually
        *build* this file don't have to do anything different.
        """
        try:
            scb = self.sbuilder
        except AttributeError:
            scb = self.sbuilder = self.find_src_builder()
        return scb is not None

    def alter_targets(self):
        """Return any corresponding targets in a variant directory.
        """
        if self.is_derived():
            return [], None
        return self.fs.variant_dir_target_climb(self, self.dir, [self.name])

    def _rmv_existing(self):
        self.clear_memoized_values()
        e = Unlink(self, [], None)
        if isinstance(e, SCons.Errors.BuildError):
            raise e

    #
    # Taskmaster interface subsystem
    #

    def make_ready(self):
        self.has_src_builder()
        self.get_binfo()

    def prepare(self):
        """Prepare for this file to be created."""
        SCons.Node.Node.prepare(self)

        if self.get_state() != SCons.Node.up_to_date:
            if self.exists():
                if self.is_derived() and not self.precious:
                    self._rmv_existing()
            else:
                try:
                    self._createDir()
                except SCons.Errors.StopError, drive:
                    desc = "No drive `%s' for target `%s'." % (drive, self)
                    raise SCons.Errors.StopError, desc

    #
    #
    #

    def remove(self):
        """Remove this file."""
        if self.exists() or self.islink():
            self.fs.unlink(self.path)
            return 1
        return None

    def do_duplicate(self, src):
        self._createDir()
        Unlink(self, None, None)
        e = Link(self, src, None)
        if isinstance(e, SCons.Errors.BuildError):
            desc = "Cannot duplicate `%s' in `%s': %s." % (src.path, self.dir.path, e.errstr)
            raise SCons.Errors.StopError, desc
        self.linked = 1
        # The Link() action may or may not have actually
        # created the file, depending on whether the -n
        # option was used or not.  Delete the _exists and
        # _rexists attributes so they can be reevaluated.
        self.clear()

    memoizer_counters.append(SCons.Memoize.CountValue('exists'))

    def exists(self):
        try:
            return self._memo['exists']
        except KeyError:
            pass
        # Duplicate from source path if we are set up to do this.
        if self.duplicate and not self.is_derived() and not self.linked:
            src = self.srcnode()
            if src is not self:
                # At this point, src is meant to be copied in a variant directory.
                src = src.rfile()
                if src.abspath != self.abspath:
                    if src.exists():
                        self.do_duplicate(src)
                        # Can't return 1 here because the duplication might
                        # not actually occur if the -n option is being used.
                    else:
                        # The source file does not exist.  Make sure no old
                        # copy remains in the variant directory.
                        if Base.exists(self) or self.islink():
                            self.fs.unlink(self.path)
                        # Return None explicitly because the Base.exists() call
                        # above will have cached its value if the file existed.
                        self._memo['exists'] = None
                        return None
        result = Base.exists(self)
        self._memo['exists'] = result
        return result

    #
    # SIGNATURE SUBSYSTEM
    #

    def get_max_drift_csig(self):
        """
        Returns the content signature currently stored for this node
        if it's been unmodified longer than the max_drift value, or the
        max_drift value is 0.  Returns None otherwise.
        """
        old = self.get_stored_info()
        mtime = self.get_timestamp()

        max_drift = self.fs.max_drift
        if max_drift > 0:
            if (time.time() - mtime) > max_drift:
                try:
                    n = old.ninfo
                    if n.timestamp and n.csig and n.timestamp == mtime:
                        return n.csig
                except AttributeError:
                    pass
        elif max_drift == 0:
            try:
                return old.ninfo.csig
            except AttributeError:
                pass

        return None

    def get_csig(self):
        """
        Generate a node's content signature, the digested signature
        of its content.

        node - the node
        cache - alternate node to use for the signature cache
        returns - the content signature
        """
        ninfo = self.get_ninfo()
        try:
            return ninfo.csig
        except AttributeError:
            pass

        csig = self.get_max_drift_csig()
        if csig is None:

            try:
                if self.get_size() < SCons.Node.FS.File.md5_chunksize:
                    contents = self.get_contents()
                else:
                    csig = self.get_content_hash()
            except IOError:
                # This can happen if there's actually a directory on-disk,
                # which can be the case if they've disabled disk checks,
                # or if an action with a File target actually happens to
                # create a same-named directory by mistake.
                csig = ''
            else:
                if not csig:
                    csig = SCons.Util.MD5signature(contents)

        ninfo.csig = csig

        return csig

    #
    # DECISION SUBSYSTEM
    #

    def builder_set(self, builder):
        SCons.Node.Node.builder_set(self, builder)
        self.changed_since_last_build = self.decide_target

    def changed_content(self, target, prev_ni):
        cur_csig = self.get_csig()
        try:
            return cur_csig != prev_ni.csig
        except AttributeError:
            return 1

    def changed_state(self, target, prev_ni):
        return self.state != SCons.Node.up_to_date

    def changed_timestamp_then_content(self, target, prev_ni):
        if not self.changed_timestamp_match(target, prev_ni):
            try:
                self.get_ninfo().csig = prev_ni.csig
            except AttributeError:
                pass
            return False
        return self.changed_content(target, prev_ni)

    def changed_timestamp_newer(self, target, prev_ni):
        try:
            return self.get_timestamp() > target.get_timestamp()
        except AttributeError:
            return 1

    def changed_timestamp_match(self, target, prev_ni):
        try:
            return self.get_timestamp() != prev_ni.timestamp
        except AttributeError:
            return 1

    def decide_source(self, target, prev_ni):
        return target.get_build_env().decide_source(self, target, prev_ni)

    def decide_target(self, target, prev_ni):
        return target.get_build_env().decide_target(self, target, prev_ni)

    # Initialize this Node's decider function to decide_source() because
    # every file is a source file until it has a Builder attached...
    changed_since_last_build = decide_source

    def is_up_to_date(self):
        T = 0
        if T: Trace('is_up_to_date(%s):' % self)
        if not self.exists():
            if T: Trace(' not self.exists():')
            # The file doesn't exist locally...
            r = self.rfile()
            if r != self:
                # ...but there is one in a Repository...
                if not self.changed(r):
                    if T: Trace(' changed(%s):' % r)
                    # ...and it's even up-to-date...
                    if self._local:
                        # ...and they'd like a local copy.
                        e = LocalCopy(self, r, None)
                        if isinstance(e, SCons.Errors.BuildError):
                            raise 
                        self.store_info()
                    if T: Trace(' 1\n')
                    return 1
            self.changed()
            if T: Trace(' None\n')
            return None
        else:
            r = self.changed()
            if T: Trace(' self.exists():  %s\n' % r)
            return not r

    memoizer_counters.append(SCons.Memoize.CountValue('rfile'))

    def rfile(self):
        try:
            return self._memo['rfile']
        except KeyError:
            pass
        result = self
        if not self.exists():
            norm_name = _my_normcase(self.name)
            for dir in self.dir.get_all_rdirs():
                try: node = dir.entries[norm_name]
                except KeyError: node = dir.file_on_disk(self.name)
                if node and node.exists() and \
                   (isinstance(node, File) or isinstance(node, Entry) \
                    or not node.is_derived()):
                        result = node
                        # Copy over our local attributes to the repository
                        # Node so we identify shared object files in the
                        # repository and don't assume they're static.
                        #
                        # This isn't perfect; the attribute would ideally
                        # be attached to the object in the repository in
                        # case it was built statically in the repository
                        # and we changed it to shared locally, but that's
                        # rarely the case and would only occur if you
                        # intentionally used the same suffix for both
                        # shared and static objects anyway.  So this
                        # should work well in practice.
                        result.attributes = self.attributes
                        break
        self._memo['rfile'] = result
        return result

    def rstr(self):
        return str(self.rfile())

    def get_cachedir_csig(self):
        """
        Fetch a Node's content signature for purposes of computing
        another Node's cachesig.

        This is a wrapper around the normal get_csig() method that handles
        the somewhat obscure case of using CacheDir with the -n option.
        Any files that don't exist would normally be "built" by fetching
        them from the cache, but the normal get_csig() method will try
        to open up the local file, which doesn't exist because the -n
        option meant we didn't actually pull the file from cachedir.
        But since the file *does* actually exist in the cachedir, we
        can use its contents for the csig.
        """
        try:
            return self.cachedir_csig
        except AttributeError:
            pass

        cachedir, cachefile = self.get_build_env().get_CacheDir().cachepath(self)
        if not self.exists() and cachefile and os.path.exists(cachefile):
            self.cachedir_csig = SCons.Util.MD5filesignature(cachefile, \
                SCons.Node.FS.File.md5_chunksize * 1024)
        else:
            self.cachedir_csig = self.get_csig()
        return self.cachedir_csig

    def get_cachedir_bsig(self):
        try:
            return self.cachesig
        except AttributeError:
            pass

        # Add the path to the cache signature, because multiple
        # targets built by the same action will all have the same
        # build signature, and we have to differentiate them somehow.
        children = self.children()
        executor = self.get_executor()
        # sigs = [n.get_cachedir_csig() for n in children]
        sigs = [n.get_cachedir_csig() for n in children]
        sigs.append(SCons.Util.MD5signature(executor.get_contents()))
        sigs.append(self.path)
        result = self.cachesig = SCons.Util.MD5collect(sigs)
        return result


default_fs = None

def get_default_fs():
    global default_fs
    if not default_fs:
        default_fs = FS()
    return default_fs

class FileFinder:
    """
    """
    if SCons.Memoize.use_memoizer:
        __metaclass__ = SCons.Memoize.Memoized_Metaclass

    memoizer_counters = []

    def __init__(self):
        self._memo = {}

    def filedir_lookup(self, p, fd=None):
        """
        A helper method for find_file() that looks up a directory for
        a file we're trying to find.  This only creates the Dir Node if
        it exists on-disk, since if the directory doesn't exist we know
        we won't find any files in it...  :-)

        It would be more compact to just use this as a nested function
        with a default keyword argument (see the commented-out version
        below), but that doesn't work unless you have nested scopes,
        so we define it here just so this work under Python 1.5.2.
        """
        if fd is None:
            fd = self.default_filedir
        dir, name = os.path.split(fd)
        drive, d = os.path.splitdrive(dir)
        if not name and d[:1] in ('/', os.sep):
            #return p.fs.get_root(drive).dir_on_disk(name)
            return p.fs.get_root(drive)
        if dir:
            p = self.filedir_lookup(p, dir)
            if not p:
                return None
        norm_name = _my_normcase(name)
        try:
            node = p.entries[norm_name]
        except KeyError:
            return p.dir_on_disk(name)
        if isinstance(node, Dir):
            return node
        if isinstance(node, Entry):
            node.must_be_same(Dir)
            return node
        return None

    def _find_file_key(self, filename, paths, verbose=None):
        return (filename, paths)
        
    memoizer_counters.append(SCons.Memoize.CountDict('find_file', _find_file_key))

    def find_file(self, filename, paths, verbose=None):
        """
        find_file(str, [Dir()]) -> [nodes]

        filename - a filename to find
        paths - a list of directory path *nodes* to search in.  Can be
                represented as a list, a tuple, or a callable that is
                called with no arguments and returns the list or tuple.

        returns - the node created from the found file.

        Find a node corresponding to either a derived file or a file
        that exists already.

        Only the first file found is returned, and none is returned
        if no file is found.
        """
        memo_key = self._find_file_key(filename, paths)
        try:
            memo_dict = self._memo['find_file']
        except KeyError:
            memo_dict = {}
            self._memo['find_file'] = memo_dict
        else:
            try:
                return memo_dict[memo_key]
            except KeyError:
                pass

        if verbose and not callable(verbose):
            if not SCons.Util.is_String(verbose):
                verbose = "find_file"
            _verbose = '  %s: ' % verbose
            verbose = lambda s: sys.stdout.write(_verbose + s)

        filedir, filename = os.path.split(filename)
        if filedir:
            # More compact code that we can't use until we drop
            # support for Python 1.5.2:
            #
            #def filedir_lookup(p, fd=filedir):
            #    """
            #    A helper function that looks up a directory for a file
            #    we're trying to find.  This only creates the Dir Node
            #    if it exists on-disk, since if the directory doesn't
            #    exist we know we won't find any files in it...  :-)
            #    """
            #    dir, name = os.path.split(fd)
            #    if dir:
            #        p = filedir_lookup(p, dir)
            #        if not p:
            #            return None
            #    norm_name = _my_normcase(name)
            #    try:
            #        node = p.entries[norm_name]
            #    except KeyError:
            #        return p.dir_on_disk(name)
            #    if isinstance(node, Dir):
            #        return node
            #    if isinstance(node, Entry):
            #        node.must_be_same(Dir)
            #        return node
            #    if isinstance(node, Dir) or isinstance(node, Entry):
            #        return node
            #    return None
            #paths = filter(None, map(filedir_lookup, paths))

            self.default_filedir = filedir
            paths = [_f for _f in map(self.filedir_lookup, paths) if _f]

        result = None
        for dir in paths:
            if verbose:
                verbose("looking for '%s' in '%s' ...\n" % (filename, dir))
            node, d = dir.srcdir_find_file(filename)
            if node:
                if verbose:
                    verbose("... FOUND '%s' in '%s'\n" % (filename, d))
                result = node
                break

        memo_dict[memo_key] = result

        return result

find_file = FileFinder().find_file


def invalidate_node_memos(targets):
    """
    Invalidate the memoized values of all Nodes (files or directories)
    that are associated with the given entries. Has been added to
    clear the cache of nodes affected by a direct execution of an
    action (e.g.  Delete/Copy/Chmod). Existing Node caches become
    inconsistent if the action is run through Execute().  The argument
    `targets` can be a single Node object or filename, or a sequence
    of Nodes/filenames.
    """
    from traceback import extract_stack

    # First check if the cache really needs to be flushed. Only
    # actions run in the SConscript with Execute() seem to be
    # affected. XXX The way to check if Execute() is in the stacktrace
    # is a very dirty hack and should be replaced by a more sensible
    # solution.
    for f in extract_stack():
        if f[2] == 'Execute' and f[0][-14:] == 'Environment.py':
            break
    else:
        # Dont have to invalidate, so return
        return

    if not SCons.Util.is_List(targets):
        targets = [targets]
    
    for entry in targets:
        # If the target is a Node object, clear the cache. If it is a
        # filename, look up potentially existing Node object first.
        try:
            entry.clear_memoized_values()
        except AttributeError:
            # Not a Node object, try to look up Node by filename.  XXX
            # This creates Node objects even for those filenames which
            # do not correspond to an existing Node object.
            node = get_default_fs().Entry(entry)
            if node:
                node.clear_memoized_values()                        

# Local Variables:
# tab-width:4
# indent-tabs-mode:nil
# End:
# vim: set expandtab tabstop=4 shiftwidth=4: