summaryrefslogtreecommitdiffstats
path: root/Lib/platform.py
blob: b9bc3036574ab65bc8d03b018f9c19c601e9fee1 (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
#!/usr/bin/env python3

""" This module tries to retrieve as much platform-identifying data as
    possible. It makes this information available via function APIs.

    If called from the command line, it prints the platform
    information concatenated as single string to stdout. The output
    format is useable as part of a filename.

"""
#    This module is maintained by Marc-Andre Lemburg <mal@egenix.com>.
#    If you find problems, please submit bug reports/patches via the
#    Python bug tracker (http://bugs.python.org) and assign them to "lemburg".
#
#    Still needed:
#    * more support for WinCE
#    * support for MS-DOS (PythonDX ?)
#    * support for Amiga and other still unsupported platforms running Python
#    * support for additional Linux distributions
#
#    Many thanks to all those who helped adding platform-specific
#    checks (in no particular order):
#
#      Charles G Waldman, David Arnold, Gordon McMillan, Ben Darnell,
#      Jeff Bauer, Cliff Crawford, Ivan Van Laningham, Josef
#      Betancourt, Randall Hopper, Karl Putland, John Farrell, Greg
#      Andruk, Just van Rossum, Thomas Heller, Mark R. Levinson, Mark
#      Hammond, Bill Tutt, Hans Nowak, Uwe Zessin (OpenVMS support),
#      Colin Kong, Trent Mick, Guido van Rossum, Anthony Baxter
#
#    History:
#
#    <see CVS and SVN checkin messages for history>
#
#    1.0.7 - added DEV_NULL
#    1.0.6 - added linux_distribution()
#    1.0.5 - fixed Java support to allow running the module on Jython
#    1.0.4 - added IronPython support
#    1.0.3 - added normalization of Windows system name
#    1.0.2 - added more Windows support
#    1.0.1 - reformatted to make doc.py happy
#    1.0.0 - reformatted a bit and checked into Python CVS
#    0.8.0 - added sys.version parser and various new access
#            APIs (python_version(), python_compiler(), etc.)
#    0.7.2 - fixed architecture() to use sizeof(pointer) where available
#    0.7.1 - added support for Caldera OpenLinux
#    0.7.0 - some fixes for WinCE; untabified the source file
#    0.6.2 - support for OpenVMS - requires version 1.5.2-V006 or higher and
#            vms_lib.getsyi() configured
#    0.6.1 - added code to prevent 'uname -p' on platforms which are
#            known not to support it
#    0.6.0 - fixed win32_ver() to hopefully work on Win95,98,NT and Win2k;
#            did some cleanup of the interfaces - some APIs have changed
#    0.5.5 - fixed another type in the MacOS code... should have
#            used more coffee today ;-)
#    0.5.4 - fixed a few typos in the MacOS code
#    0.5.3 - added experimental MacOS support; added better popen()
#            workarounds in _syscmd_ver() -- still not 100% elegant
#            though
#    0.5.2 - fixed uname() to return '' instead of 'unknown' in all
#            return values (the system uname command tends to return
#            'unknown' instead of just leaving the field emtpy)
#    0.5.1 - included code for slackware dist; added exception handlers
#            to cover up situations where platforms don't have os.popen
#            (e.g. Mac) or fail on socket.gethostname(); fixed libc
#            detection RE
#    0.5.0 - changed the API names referring to system commands to *syscmd*;
#            added java_ver(); made syscmd_ver() a private
#            API (was system_ver() in previous versions) -- use uname()
#            instead; extended the win32_ver() to also return processor
#            type information
#    0.4.0 - added win32_ver() and modified the platform() output for WinXX
#    0.3.4 - fixed a bug in _follow_symlinks()
#    0.3.3 - fixed popen() and "file" command invokation bugs
#    0.3.2 - added architecture() API and support for it in platform()
#    0.3.1 - fixed syscmd_ver() RE to support Windows NT
#    0.3.0 - added system alias support
#    0.2.3 - removed 'wince' again... oh well.
#    0.2.2 - added 'wince' to syscmd_ver() supported platforms
#    0.2.1 - added cache logic and changed the platform string format
#    0.2.0 - changed the API to use functions instead of module globals
#            since some action take too long to be run on module import
#    0.1.0 - first release
#
#    You can always get the latest version of this module at:
#
#             http://www.egenix.com/files/python/platform.py
#
#    If that URL should fail, try contacting the author.

__copyright__ = """
    Copyright (c) 1999-2000, Marc-Andre Lemburg; mailto:mal@lemburg.com
    Copyright (c) 2000-2010, eGenix.com Software GmbH; mailto:info@egenix.com

    Permission to use, copy, modify, and distribute this software and its
    documentation for any purpose and without fee or royalty is hereby granted,
    provided that the above copyright notice appear in all copies and that
    both that copyright notice and this permission notice appear in
    supporting documentation or portions thereof, including modifications,
    that you make.

    EGENIX.COM SOFTWARE GMBH DISCLAIMS ALL WARRANTIES WITH REGARD TO
    THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
    FITNESS, IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL,
    INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
    FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
    NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
    WITH THE USE OR PERFORMANCE OF THIS SOFTWARE !

"""

__version__ = '1.0.7'

import sys, os, re

### Globals & Constants

# Determine the platform's /dev/null device
try:
    DEV_NULL = os.devnull
except AttributeError:
    # os.devnull was added in Python 2.4, so emulate it for earlier
    # Python versions
    if sys.platform in ('dos','win32','win16','os2'):
        # Use the old CP/M NUL as device name
        DEV_NULL = 'NUL'
    else:
        # Standard Unix uses /dev/null
        DEV_NULL = '/dev/null'

### Platform specific APIs

_libc_search = re.compile(r'(__libc_init)'
                          '|'
                          '(GLIBC_([0-9.]+))'
                          '|'
                          '(libc(_\w+)?\.so(?:\.(\d[0-9.]*))?)', re.ASCII)

def libc_ver(executable=sys.executable,lib='',version='',

             chunksize=2048):

    """ Tries to determine the libc version that the file executable
        (which defaults to the Python interpreter) is linked against.

        Returns a tuple of strings (lib,version) which default to the
        given parameters in case the lookup fails.

        Note that the function has intimate knowledge of how different
        libc versions add symbols to the executable and thus is probably
        only useable for executables compiled using gcc.

        The file is read and scanned in chunks of chunksize bytes.

    """
    if hasattr(os.path, 'realpath'):
        # Python 2.2 introduced os.path.realpath(); it is used
        # here to work around problems with Cygwin not being
        # able to open symlinks for reading
        executable = os.path.realpath(executable)
    f = open(executable,'rb')
    binary = f.read(chunksize).decode('latin-1')
    pos = 0
    while 1:
        m = _libc_search.search(binary,pos)
        if not m:
            binary = f.read(chunksize).decode('latin-1')
            if not binary:
                break
            pos = 0
            continue
        libcinit,glibc,glibcversion,so,threads,soversion = m.groups()
        if libcinit and not lib:
            lib = 'libc'
        elif glibc:
            if lib != 'glibc':
                lib = 'glibc'
                version = glibcversion
            elif glibcversion > version:
                version = glibcversion
        elif so:
            if lib != 'glibc':
                lib = 'libc'
                if soversion > version:
                    version = soversion
                if threads and version[-len(threads):] != threads:
                    version = version + threads
        pos = m.end()
    f.close()
    return lib,version

def _dist_try_harder(distname,version,id):

    """ Tries some special tricks to get the distribution
        information in case the default method fails.

        Currently supports older SuSE Linux, Caldera OpenLinux and
        Slackware Linux distributions.

    """
    if os.path.exists('/var/adm/inst-log/info'):
        # SuSE Linux stores distribution information in that file
        distname = 'SuSE'
        for line in open('/var/adm/inst-log/info'):
            tv = line.split()
            if len(tv) == 2:
                tag,value = tv
            else:
                continue
            if tag == 'MIN_DIST_VERSION':
                version = value.strip()
            elif tag == 'DIST_IDENT':
                values = value.split('-')
                id = values[2]
        return distname,version,id

    if os.path.exists('/etc/.installed'):
        # Caldera OpenLinux has some infos in that file (thanks to Colin Kong)
        for line in open('/etc/.installed'):
            pkg = line.split('-')
            if len(pkg) >= 2 and pkg[0] == 'OpenLinux':
                # XXX does Caldera support non Intel platforms ? If yes,
                #     where can we find the needed id ?
                return 'OpenLinux',pkg[1],id

    if os.path.isdir('/usr/lib/setup'):
        # Check for slackware verson tag file (thanks to Greg Andruk)
        verfiles = os.listdir('/usr/lib/setup')
        for n in range(len(verfiles)-1, -1, -1):
            if verfiles[n][:14] != 'slack-version-':
                del verfiles[n]
        if verfiles:
            verfiles.sort()
            distname = 'slackware'
            version = verfiles[-1][14:]
            return distname,version,id

    return distname,version,id

_release_filename = re.compile(r'(\w+)[-_](release|version)', re.ASCII)
_lsb_release_version = re.compile(r'(.+)'
                                   ' release '
                                   '([\d.]+)'
                                   '[^(]*(?:\((.+)\))?', re.ASCII)
_release_version = re.compile(r'([^0-9]+)'
                               '(?: release )?'
                               '([\d.]+)'
                               '[^(]*(?:\((.+)\))?', re.ASCII)

# See also http://www.novell.com/coolsolutions/feature/11251.html
# and http://linuxmafia.com/faq/Admin/release-files.html
# and http://data.linux-ntfs.org/rpm/whichrpm
# and http://www.die.net/doc/linux/man/man1/lsb_release.1.html

_supported_dists = (
    'SuSE', 'debian', 'fedora', 'redhat', 'centos',
    'mandrake', 'mandriva', 'rocks', 'slackware', 'yellowdog', 'gentoo',
    'UnitedLinux', 'turbolinux')

def _parse_release_file(firstline):

    # Default to empty 'version' and 'id' strings.  Both defaults are used
    # when 'firstline' is empty.  'id' defaults to empty when an id can not
    # be deduced.
    version = ''
    id = ''

    # Parse the first line
    m = _lsb_release_version.match(firstline)
    if m is not None:
        # LSB format: "distro release x.x (codename)"
        return tuple(m.groups())

    # Pre-LSB format: "distro x.x (codename)"
    m = _release_version.match(firstline)
    if m is not None:
        return tuple(m.groups())

    # Unkown format... take the first two words
    l = firstline.strip().split()
    if l:
        version = l[0]
        if len(l) > 1:
            id = l[1]
    return '', version, id

def linux_distribution(distname='', version='', id='',

                       supported_dists=_supported_dists,
                       full_distribution_name=1):

    """ Tries to determine the name of the Linux OS distribution name.

        The function first looks for a distribution release file in
        /etc and then reverts to _dist_try_harder() in case no
        suitable files are found.

        supported_dists may be given to define the set of Linux
        distributions to look for. It defaults to a list of currently
        supported Linux distributions identified by their release file
        name.

        If full_distribution_name is true (default), the full
        distribution read from the OS is returned. Otherwise the short
        name taken from supported_dists is used.

        Returns a tuple (distname,version,id) which default to the
        args given as parameters.

    """
    try:
        etc = os.listdir('/etc')
    except os.error:
        # Probably not a Unix system
        return distname,version,id
    etc.sort()
    for file in etc:
        m = _release_filename.match(file)
        if m is not None:
            _distname,dummy = m.groups()
            if _distname in supported_dists:
                distname = _distname
                break
    else:
        return _dist_try_harder(distname,version,id)

    # Read the first line
    with open('/etc/'+file, 'r') as f:
        firstline = f.readline()
    _distname, _version, _id = _parse_release_file(firstline)

    if _distname and full_distribution_name:
        distname = _distname
    if _version:
        version = _version
    if _id:
        id = _id
    return distname, version, id

# To maintain backwards compatibility:

def dist(distname='',version='',id='',

         supported_dists=_supported_dists):

    """ Tries to determine the name of the Linux OS distribution name.

        The function first looks for a distribution release file in
        /etc and then reverts to _dist_try_harder() in case no
        suitable files are found.

        Returns a tuple (distname,version,id) which default to the
        args given as parameters.

    """
    return linux_distribution(distname, version, id,
                              supported_dists=supported_dists,
                              full_distribution_name=0)

class _popen:

    """ Fairly portable (alternative) popen implementation.

        This is mostly needed in case os.popen() is not available, or
        doesn't work as advertised, e.g. in Win9X GUI programs like
        PythonWin or IDLE.

        Writing to the pipe is currently not supported.

    """
    tmpfile = ''
    pipe = None
    bufsize = None
    mode = 'r'

    def __init__(self,cmd,mode='r',bufsize=None):

        if mode != 'r':
            raise ValueError('popen()-emulation only supports read mode')
        import tempfile
        self.tmpfile = tmpfile = tempfile.mktemp()
        os.system(cmd + ' > %s' % tmpfile)
        self.pipe = open(tmpfile,'rb')
        self.bufsize = bufsize
        self.mode = mode

    def read(self):

        return self.pipe.read()

    def readlines(self):

        if self.bufsize is not None:
            return self.pipe.readlines()

    def close(self,

              remove=os.unlink,error=os.error):

        if self.pipe:
            rc = self.pipe.close()
        else:
            rc = 255
        if self.tmpfile:
            try:
                remove(self.tmpfile)
            except error:
                pass
        return rc

    # Alias
    __del__ = close

def popen(cmd, mode='r', bufsize=None):

    """ Portable popen() interface.
    """
    # Find a working popen implementation preferring win32pipe.popen
    # over os.popen over _popen
    popen = None
    if os.environ.get('OS','') == 'Windows_NT':
        # On NT win32pipe should work; on Win9x it hangs due to bugs
        # in the MS C lib (see MS KnowledgeBase article Q150956)
        try:
            import win32pipe
        except ImportError:
            pass
        else:
            popen = win32pipe.popen
    if popen is None:
        if hasattr(os,'popen'):
            popen = os.popen
            # Check whether it works... it doesn't in GUI programs
            # on Windows platforms
            if sys.platform == 'win32': # XXX Others too ?
                try:
                    popen('')
                except os.error:
                    popen = _popen
        else:
            popen = _popen
    if bufsize is None:
        return popen(cmd,mode)
    else:
        return popen(cmd,mode,bufsize)

def _norm_version(version, build=''):

    """ Normalize the version and build strings and return a single
        version string using the format major.minor.build (or patchlevel).
    """
    l = version.split('.')
    if build:
        l.append(build)
    try:
        ints = map(int,l)
    except ValueError:
        strings = l
    else:
        strings = list(map(str,ints))
    version = '.'.join(strings[:3])
    return version

_ver_output = re.compile(r'(?:([\w ]+) ([\w.]+) '
                         '.*'
                         '\[.* ([\d.]+)\])')

# Examples of VER command output:
#
#   Windows 2000:  Microsoft Windows 2000 [Version 5.00.2195]
#   Windows XP:    Microsoft Windows XP [Version 5.1.2600]
#   Windows Vista: Microsoft Windows [Version 6.0.6002]
#
# Note that the "Version" string gets localized on different
# Windows versions.

def _syscmd_ver(system='', release='', version='',

               supported_platforms=('win32','win16','dos','os2')):

    """ Tries to figure out the OS version used and returns
        a tuple (system,release,version).

        It uses the "ver" shell command for this which is known
        to exists on Windows, DOS and OS/2. XXX Others too ?

        In case this fails, the given parameters are used as
        defaults.

    """
    if sys.platform not in supported_platforms:
        return system,release,version

    # Try some common cmd strings
    for cmd in ('ver','command /c ver','cmd /c ver'):
        try:
            pipe = popen(cmd)
            info = pipe.read()
            if pipe.close():
                raise os.error('command failed')
            # XXX How can I supress shell errors from being written
            #     to stderr ?
        except os.error as why:
            #print 'Command %s failed: %s' % (cmd,why)
            continue
        except IOError as why:
            #print 'Command %s failed: %s' % (cmd,why)
            continue
        else:
            break
    else:
        return system,release,version

    # Parse the output
    info = info.strip()
    m = _ver_output.match(info)
    if m is not None:
        system,release,version = m.groups()
        # Strip trailing dots from version and release
        if release[-1] == '.':
            release = release[:-1]
        if version[-1] == '.':
            version = version[:-1]
        # Normalize the version and build strings (eliminating additional
        # zeros)
        version = _norm_version(version)
    return system,release,version

def _win32_getvalue(key,name,default=''):

    """ Read a value for name from the registry key.

        In case this fails, default is returned.

    """
    try:
        # Use win32api if available
        from win32api import RegQueryValueEx
    except ImportError:
        # On Python 2.0 and later, emulate using winreg
        import winreg
        RegQueryValueEx = winreg.QueryValueEx
    try:
        return RegQueryValueEx(key,name)
    except:
        return default

def win32_ver(release='',version='',csd='',ptype=''):

    """ Get additional version information from the Windows Registry
        and return a tuple (version,csd,ptype) referring to version
        number, CSD level and OS type (multi/single
        processor).

        As a hint: ptype returns 'Uniprocessor Free' on single
        processor NT machines and 'Multiprocessor Free' on multi
        processor machines. The 'Free' refers to the OS version being
        free of debugging code. It could also state 'Checked' which
        means the OS version uses debugging code, i.e. code that
        checks arguments, ranges, etc. (Thomas Heller).

        Note: this function works best with Mark Hammond's win32
        package installed, but also on Python 2.3 and later. It
        obviously only runs on Win32 compatible platforms.

    """
    # XXX Is there any way to find out the processor type on WinXX ?
    # XXX Is win32 available on Windows CE ?
    #
    # Adapted from code posted by Karl Putland to comp.lang.python.
    #
    # The mappings between reg. values and release names can be found
    # here: http://msdn.microsoft.com/library/en-us/sysinfo/base/osversioninfo_str.asp

    # Import the needed APIs
    try:
        import win32api
        from win32api import RegQueryValueEx, RegOpenKeyEx, \
             RegCloseKey, GetVersionEx
        from win32con import HKEY_LOCAL_MACHINE, VER_PLATFORM_WIN32_NT, \
             VER_PLATFORM_WIN32_WINDOWS, VER_NT_WORKSTATION
    except ImportError:
        # Emulate the win32api module using Python APIs
        try:
            sys.getwindowsversion
        except AttributeError:
            # No emulation possible, so return the defaults...
            return release,version,csd,ptype
        else:
            # Emulation using winreg (added in Python 2.0) and
            # sys.getwindowsversion() (added in Python 2.3)
            import winreg
            GetVersionEx = sys.getwindowsversion
            RegQueryValueEx = winreg.QueryValueEx
            RegOpenKeyEx = winreg.OpenKeyEx
            RegCloseKey = winreg.CloseKey
            HKEY_LOCAL_MACHINE = winreg.HKEY_LOCAL_MACHINE
            VER_PLATFORM_WIN32_WINDOWS = 1
            VER_PLATFORM_WIN32_NT = 2
            VER_NT_WORKSTATION = 1
            VER_NT_SERVER = 3
            REG_SZ = 1

    # Find out the registry key and some general version infos
    winver = GetVersionEx()
    maj,min,buildno,plat,csd = winver
    version = '%i.%i.%i' % (maj,min,buildno & 0xFFFF)
    if hasattr(winver, "service_pack"):
        if winver.service_pack != "":
            csd = 'SP%s' % winver.service_pack_major
    else:
        if csd[:13] == 'Service Pack ':
            csd = 'SP' + csd[13:]

    if plat == VER_PLATFORM_WIN32_WINDOWS:
        regkey = 'SOFTWARE\\Microsoft\\Windows\\CurrentVersion'
        # Try to guess the release name
        if maj == 4:
            if min == 0:
                release = '95'
            elif min == 10:
                release = '98'
            elif min == 90:
                release = 'Me'
            else:
                release = 'postMe'
        elif maj == 5:
            release = '2000'

    elif plat == VER_PLATFORM_WIN32_NT:
        regkey = 'SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion'
        if maj <= 4:
            release = 'NT'
        elif maj == 5:
            if min == 0:
                release = '2000'
            elif min == 1:
                release = 'XP'
            elif min == 2:
                release = '2003Server'
            else:
                release = 'post2003'
        elif maj == 6:
            if hasattr(winver, "product_type"):
                product_type = winver.product_type
            else:
                product_type = VER_NT_WORKSTATION
                # Without an OSVERSIONINFOEX capable sys.getwindowsversion(),
                # or help from the registry, we cannot properly identify
                # non-workstation versions.
                try:
                    key = RegOpenKeyEx(HKEY_LOCAL_MACHINE, regkey)
                    name, type = RegQueryValueEx(key, "ProductName")
                    # Discard any type that isn't REG_SZ
                    if type == REG_SZ and name.find("Server") != -1:
                        product_type = VER_NT_SERVER
                except WindowsError:
                    # Use default of VER_NT_WORKSTATION
                    pass

            if min == 0:
                if product_type == VER_NT_WORKSTATION:
                    release = 'Vista'
                else:
                    release = '2008Server'
            elif min == 1:
                if product_type == VER_NT_WORKSTATION:
                    release = '7'
                else:
                    release = '2008ServerR2'
            else:
                release = 'post2008Server'

    else:
        if not release:
            # E.g. Win3.1 with win32s
            release = '%i.%i' % (maj,min)
        return release,version,csd,ptype

    # Open the registry key
    try:
        keyCurVer = RegOpenKeyEx(HKEY_LOCAL_MACHINE, regkey)
        # Get a value to make sure the key exists...
        RegQueryValueEx(keyCurVer, 'SystemRoot')
    except:
        return release,version,csd,ptype

    # Parse values
    #subversion = _win32_getvalue(keyCurVer,
    #                            'SubVersionNumber',
    #                            ('',1))[0]
    #if subversion:
    #   release = release + subversion # 95a, 95b, etc.
    build = _win32_getvalue(keyCurVer,
                            'CurrentBuildNumber',
                            ('',1))[0]
    ptype = _win32_getvalue(keyCurVer,
                           'CurrentType',
                           (ptype,1))[0]

    # Normalize version
    version = _norm_version(version,build)

    # Close key
    RegCloseKey(keyCurVer)
    return release,version,csd,ptype

def _mac_ver_lookup(selectors,default=None):

    from _gestalt import gestalt
    l = []
    append = l.append
    for selector in selectors:
        try:
            append(gestalt(selector))
        except (RuntimeError, OSError):
            append(default)
    return l

def _bcd2str(bcd):

    return hex(bcd)[2:]

def _mac_ver_gestalt():
    """
        Thanks to Mark R. Levinson for mailing documentation links and
        code examples for this function. Documentation for the
        gestalt() API is available online at:

           http://www.rgaros.nl/gestalt/
    """
    # Check whether the version info module is available
    try:
        import _gestalt
    except ImportError:
        return None
    # Get the infos
    sysv, sysa = _mac_ver_lookup(('sysv','sysa'))
    # Decode the infos
    if sysv:
        major = (sysv & 0xFF00) >> 8
        minor = (sysv & 0x00F0) >> 4
        patch = (sysv & 0x000F)

        if (major, minor) >= (10, 4):
            # the 'sysv' gestald cannot return patchlevels
            # higher than 9. Apple introduced 3 new
            # gestalt codes in 10.4 to deal with this
            # issue (needed because patch levels can
            # run higher than 9, such as 10.4.11)
            major,minor,patch = _mac_ver_lookup(('sys1','sys2','sys3'))
            release = '%i.%i.%i' %(major, minor, patch)
        else:
            release = '%s.%i.%i' % (_bcd2str(major),minor,patch)

    if sysa:
        machine = {0x1: '68k',
                   0x2: 'PowerPC',
                   0xa: 'i386'}.get(sysa,'')

    return release,versioninfo,machine

def _mac_ver_xml():
    fn = '/System/Library/CoreServices/SystemVersion.plist'
    if not os.path.exists(fn):
        return None

    try:
        import plistlib
    except ImportError:
        return None

    pl = plistlib.readPlist(fn)
    release = pl['ProductVersion']
    versioninfo=('', '', '')
    machine = os.uname()[4]
    if machine in ('ppc', 'Power Macintosh'):
        # for compatibility with the gestalt based code
        machine = 'PowerPC'

    return release,versioninfo,machine


def mac_ver(release='',versioninfo=('','',''),machine=''):

    """ Get MacOS version information and return it as tuple (release,
        versioninfo, machine) with versioninfo being a tuple (version,
        dev_stage, non_release_version).

        Entries which cannot be determined are set to the paramter values
        which default to ''. All tuple entries are strings.
    """

    # First try reading the information from an XML file which should
    # always be present
    info = _mac_ver_xml()
    if info is not None:
        return info

    # If that doesn't work for some reason fall back to reading the
    # information using gestalt calls.
    info = _mac_ver_gestalt()
    if info is not None:
        return info

    # If that also doesn't work return the default values
    return release,versioninfo,machine

def _java_getprop(name,default):

    from java.lang import System
    try:
        value = System.getProperty(name)
        if value is None:
            return default
        return value
    except AttributeError:
        return default

def java_ver(release='',vendor='',vminfo=('','',''),osinfo=('','','')):

    """ Version interface for Jython.

        Returns a tuple (release,vendor,vminfo,osinfo) with vminfo being
        a tuple (vm_name,vm_release,vm_vendor) and osinfo being a
        tuple (os_name,os_version,os_arch).

        Values which cannot be determined are set to the defaults
        given as parameters (which all default to '').

    """
    # Import the needed APIs
    try:
        import java.lang
    except ImportError:
        return release,vendor,vminfo,osinfo

    vendor = _java_getprop('java.vendor', vendor)
    release = _java_getprop('java.version', release)
    vm_name, vm_release, vm_vendor = vminfo
    vm_name = _java_getprop('java.vm.name', vm_name)
    vm_vendor = _java_getprop('java.vm.vendor', vm_vendor)
    vm_release = _java_getprop('java.vm.version', vm_release)
    vminfo = vm_name, vm_release, vm_vendor
    os_name, os_version, os_arch = osinfo
    os_arch = _java_getprop('java.os.arch', os_arch)
    os_name = _java_getprop('java.os.name', os_name)
    os_version = _java_getprop('java.os.version', os_version)
    osinfo = os_name, os_version, os_arch

    return release, vendor, vminfo, osinfo

### System name aliasing

def system_alias(system,release,version):

    """ Returns (system,release,version) aliased to common
        marketing names used for some systems.

        It also does some reordering of the information in some cases
        where it would otherwise cause confusion.

    """
    if system == 'Rhapsody':
        # Apple's BSD derivative
        # XXX How can we determine the marketing release number ?
        return 'MacOS X Server',system+release,version

    elif system == 'SunOS':
        # Sun's OS
        if release < '5':
            # These releases use the old name SunOS
            return system,release,version
        # Modify release (marketing release = SunOS release - 3)
        l = release.split('.')
        if l:
            try:
                major = int(l[0])
            except ValueError:
                pass
            else:
                major = major - 3
                l[0] = str(major)
                release = '.'.join(l)
        if release < '6':
            system = 'Solaris'
        else:
            # XXX Whatever the new SunOS marketing name is...
            system = 'Solaris'

    elif system == 'IRIX64':
        # IRIX reports IRIX64 on platforms with 64-bit support; yet it
        # is really a version and not a different platform, since 32-bit
        # apps are also supported..
        system = 'IRIX'
        if version:
            version = version + ' (64bit)'
        else:
            version = '64bit'

    elif system in ('win32','win16'):
        # In case one of the other tricks
        system = 'Windows'

    return system,release,version

### Various internal helpers

def _platform(*args):

    """ Helper to format the platform string in a filename
        compatible format e.g. "system-version-machine".
    """
    # Format the platform string
    platform = '-'.join(x.strip() for x in filter(len, args))

    # Cleanup some possible filename obstacles...
    platform = platform.replace(' ','_')
    platform = platform.replace('/','-')
    platform = platform.replace('\\','-')
    platform = platform.replace(':','-')
    platform = platform.replace(';','-')
    platform = platform.replace('"','-')
    platform = platform.replace('(','-')
    platform = platform.replace(')','-')

    # No need to report 'unknown' information...
    platform = platform.replace('unknown','')

    # Fold '--'s and remove trailing '-'
    while 1:
        cleaned = platform.replace('--','-')
        if cleaned == platform:
            break
        platform = cleaned
    while platform[-1] == '-':
        platform = platform[:-1]

    return platform

def _node(default=''):

    """ Helper to determine the node name of this machine.
    """
    try:
        import socket
    except ImportError:
        # No sockets...
        return default
    try:
        return socket.gethostname()
    except socket.error:
        # Still not working...
        return default

def _follow_symlinks(filepath):

    """ In case filepath is a symlink, follow it until a
        real file is reached.
    """
    filepath = os.path.abspath(filepath)
    while os.path.islink(filepath):
        filepath = os.path.normpath(
            os.path.join(os.path.dirname(filepath),os.readlink(filepath)))
    return filepath

def _syscmd_uname(option,default=''):

    """ Interface to the system's uname command.
    """
    if sys.platform in ('dos','win32','win16','os2'):
        # XXX Others too ?
        return default
    try:
        f = os.popen('uname %s 2> %s' % (option, DEV_NULL))
    except (AttributeError,os.error):
        return default
    output = f.read().strip()
    rc = f.close()
    if not output or rc:
        return default
    else:
        return output

def _syscmd_file(target,default=''):

    """ Interface to the system's file command.

        The function uses the -b option of the file command to have it
        omit the filename in its output. Follow the symlinks. It returns
        default in case the command should fail.

    """
    if sys.platform in ('dos','win32','win16','os2'):
        # XXX Others too ?
        return default
    target = _follow_symlinks(target).replace('"', '\\"')
    try:
        f = os.popen('file -b "%s" 2> %s' % (target, DEV_NULL))
    except (AttributeError,os.error):
        return default
    output = f.read().strip()
    rc = f.close()
    if not output or rc:
        return default
    else:
        return output

### Information about the used architecture

# Default values for architecture; non-empty strings override the
# defaults given as parameters
_default_architecture = {
    'win32': ('','WindowsPE'),
    'win16': ('','Windows'),
    'dos': ('','MSDOS'),
}

def architecture(executable=sys.executable,bits='',linkage=''):

    """ Queries the given executable (defaults to the Python interpreter
        binary) for various architecture information.

        Returns a tuple (bits,linkage) which contains information about
        the bit architecture and the linkage format used for the
        executable. Both values are returned as strings.

        Values that cannot be determined are returned as given by the
        parameter presets. If bits is given as '', the sizeof(pointer)
        (or sizeof(long) on Python version < 1.5.2) is used as
        indicator for the supported pointer size.

        The function relies on the system's "file" command to do the
        actual work. This is available on most if not all Unix
        platforms. On some non-Unix platforms where the "file" command
        does not exist and the executable is set to the Python interpreter
        binary defaults from _default_architecture are used.

    """
    # Use the sizeof(pointer) as default number of bits if nothing
    # else is given as default.
    if not bits:
        import struct
        try:
            size = struct.calcsize('P')
        except struct.error:
            # Older installations can only query longs
            size = struct.calcsize('l')
        bits = str(size*8) + 'bit'

    # Get data from the 'file' system command
    if executable:
        fileout = _syscmd_file(executable, '')
    else:
        fileout = ''

    if not fileout and \
       executable == sys.executable:
        # "file" command did not return anything; we'll try to provide
        # some sensible defaults then...
        if sys.platform in _default_architecture:
            b,l = _default_architecture[sys.platform]
            if b:
                bits = b
            if l:
                linkage = l
        return bits,linkage

    if 'executable' not in fileout:
        # Format not supported
        return bits,linkage

    # Bits
    if '32-bit' in fileout:
        bits = '32bit'
    elif 'N32' in fileout:
        # On Irix only
        bits = 'n32bit'
    elif '64-bit' in fileout:
        bits = '64bit'

    # Linkage
    if 'ELF' in fileout:
        linkage = 'ELF'
    elif 'PE' in fileout:
        # E.g. Windows uses this format
        if 'Windows' in fileout:
            linkage = 'WindowsPE'
        else:
            linkage = 'PE'
    elif 'COFF' in fileout:
        linkage = 'COFF'
    elif 'MS-DOS' in fileout:
        linkage = 'MSDOS'
    else:
        # XXX the A.OUT format also falls under this class...
        pass

    return bits,linkage

### Portable uname() interface

_uname_cache = None

def uname():

    """ Fairly portable uname interface. Returns a tuple
        of strings (system,node,release,version,machine,processor)
        identifying the underlying platform.

        Note that unlike the os.uname function this also returns
        possible processor information as an additional tuple entry.

        Entries which cannot be determined are set to ''.

    """
    global _uname_cache
    no_os_uname = 0

    if _uname_cache is not None:
        return _uname_cache

    processor = ''

    # Get some infos from the builtin os.uname API...
    try:
        system,node,release,version,machine = os.uname()
    except AttributeError:
        no_os_uname = 1

    if no_os_uname or not list(filter(None, (system, node, release, version, machine))):
        # Hmm, no there is either no uname or uname has returned
        #'unknowns'... we'll have to poke around the system then.
        if no_os_uname:
            system = sys.platform
            release = ''
            version = ''
            node = _node()
            machine = ''

        use_syscmd_ver = 1

        # Try win32_ver() on win32 platforms
        if system == 'win32':
            release,version,csd,ptype = win32_ver()
            if release and version:
                use_syscmd_ver = 0
            # Try to use the PROCESSOR_* environment variables
            # available on Win XP and later; see
            # http://support.microsoft.com/kb/888731 and
            # http://www.geocities.com/rick_lively/MANUALS/ENV/MSWIN/PROCESSI.HTM
            if not machine:
                # WOW64 processes mask the native architecture
                if "PROCESSOR_ARCHITEW6432" in os.environ:
                    machine = os.environ.get("PROCESSOR_ARCHITEW6432", '')
                else:
                    machine = os.environ.get('PROCESSOR_ARCHITECTURE', '')
            if not processor:
                processor = os.environ.get('PROCESSOR_IDENTIFIER', machine)

        # Try the 'ver' system command available on some
        # platforms
        if use_syscmd_ver:
            system,release,version = _syscmd_ver(system)
            # Normalize system to what win32_ver() normally returns
            # (_syscmd_ver() tends to return the vendor name as well)
            if system == 'Microsoft Windows':
                system = 'Windows'
            elif system == 'Microsoft' and release == 'Windows':
                # Under Windows Vista and Windows Server 2008,
                # Microsoft changed the output of the ver command. The
                # release is no longer printed.  This causes the
                # system and release to be misidentified.
                system = 'Windows'
                if '6.0' == version[:3]:
                    release = 'Vista'
                else:
                    release = ''

        # In case we still don't know anything useful, we'll try to
        # help ourselves
        if system in ('win32','win16'):
            if not version:
                if system == 'win32':
                    version = '32bit'
                else:
                    version = '16bit'
            system = 'Windows'

        elif system[:4] == 'java':
            release,vendor,vminfo,osinfo = java_ver()
            system = 'Java'
            version = ', '.join(vminfo)
            if not version:
                version = vendor

    # System specific extensions
    if system == 'OpenVMS':
        # OpenVMS seems to have release and version mixed up
        if not release or release == '0':
            release = version
            version = ''
        # Get processor information
        try:
            import vms_lib
        except ImportError:
            pass
        else:
            csid, cpu_number = vms_lib.getsyi('SYI$_CPU',0)
            if (cpu_number >= 128):
                processor = 'Alpha'
            else:
                processor = 'VAX'
    if not processor:
        # Get processor information from the uname system command
        processor = _syscmd_uname('-p','')

    #If any unknowns still exist, replace them with ''s, which are more portable
    if system == 'unknown':
        system = ''
    if node == 'unknown':
        node = ''
    if release == 'unknown':
        release = ''
    if version == 'unknown':
        version = ''
    if machine == 'unknown':
        machine = ''
    if processor == 'unknown':
        processor = ''

    #  normalize name
    if system == 'Microsoft' and release == 'Windows':
        system = 'Windows'
        release = 'Vista'

    _uname_cache = system,node,release,version,machine,processor
    return _uname_cache

### Direct interfaces to some of the uname() return values

def system():

    """ Returns the system/OS name, e.g. 'Linux', 'Windows' or 'Java'.

        An empty string is returned if the value cannot be determined.

    """
    return uname()[0]

def node():

    """ Returns the computer's network name (which may not be fully
        qualified)

        An empty string is returned if the value cannot be determined.

    """
    return uname()[1]

def release():

    """ Returns the system's release, e.g. '2.2.0' or 'NT'

        An empty string is returned if the value cannot be determined.

    """
    return uname()[2]

def version():

    """ Returns the system's release version, e.g. '#3 on degas'

        An empty string is returned if the value cannot be determined.

    """
    return uname()[3]

def machine():

    """ Returns the machine type, e.g. 'i386'

        An empty string is returned if the value cannot be determined.

    """
    return uname()[4]

def processor():

    """ Returns the (true) processor name, e.g. 'amdk6'

        An empty string is returned if the value cannot be
        determined. Note that many platforms do not provide this
        information or simply return the same value as for machine(),
        e.g.  NetBSD does this.

    """
    return uname()[5]

### Various APIs for extracting information from sys.version

_sys_version_parser = re.compile(
    r'([\w.+]+)\s*'
    '\(#?([^,]+),\s*([\w ]+),\s*([\w :]+)\)\s*'
    '\[([^\]]+)\]?', re.ASCII)

_ironpython_sys_version_parser = re.compile(
    r'IronPython\s*'
    '([\d\.]+)'
    '(?: \(([\d\.]+)\))?'
    ' on (.NET [\d\.]+)', re.ASCII)

_pypy_sys_version_parser = re.compile(
    r'([\w.+]+)\s*'
    '\(#?([^,]+),\s*([\w ]+),\s*([\w :]+)\)\s*'
    '\[PyPy [^\]]+\]?')

_sys_version_cache = {}

def _sys_version(sys_version=None):

    """ Returns a parsed version of Python's sys.version as tuple
        (name, version, branch, revision, buildno, builddate, compiler)
        referring to the Python implementation name, version, branch,
        revision, build number, build date/time as string and the compiler
        identification string.

        Note that unlike the Python sys.version, the returned value
        for the Python version will always include the patchlevel (it
        defaults to '.0').

        The function returns empty strings for tuple entries that
        cannot be determined.

        sys_version may be given to parse an alternative version
        string, e.g. if the version was read from a different Python
        interpreter.

    """
    # Get the Python version
    if sys_version is None:
        sys_version = sys.version

    # Try the cache first
    result = _sys_version_cache.get(sys_version, None)
    if result is not None:
        return result

    # Parse it
    if sys_version[:10] == 'IronPython':
        # IronPython
        name = 'IronPython'
        match = _ironpython_sys_version_parser.match(sys_version)
        if match is None:
            raise ValueError(
                'failed to parse IronPython sys.version: %s' %
                repr(sys_version))
        version, alt_version, compiler = match.groups()
        buildno = ''
        builddate = ''

    elif sys.platform[:4] == 'java':
        # Jython
        name = 'Jython'
        match = _sys_version_parser.match(sys_version)
        if match is None:
            raise ValueError(
                'failed to parse Jython sys.version: %s' %
                repr(sys_version))
        version, buildno, builddate, buildtime, _ = match.groups()
        compiler = sys.platform

    elif "PyPy" in sys_version:
        # PyPy
        name = "PyPy"
        match = _pypy_sys_version_parser.match(sys_version)
        if match is None:
            raise ValueError("failed to parse PyPy sys.version: %s" %
                             repr(sys_version))
        version, buildno, builddate, buildtime = match.groups()
        compiler = ""

    else:
        # CPython
        match = _sys_version_parser.match(sys_version)
        if match is None:
            raise ValueError(
                'failed to parse CPython sys.version: %s' %
                repr(sys_version))
        version, buildno, builddate, buildtime, compiler = \
              match.groups()
        name = 'CPython'
        builddate = builddate + ' ' + buildtime

    if hasattr(sys, 'subversion'):
        # sys.subversion was added in Python 2.5
        _, branch, revision = sys.subversion
    else:
        branch = ''
        revision = ''

    # Add the patchlevel version if missing
    l = version.split('.')
    if len(l) == 2:
        l.append('0')
        version = '.'.join(l)

    # Build and cache the result
    result = (name, version, branch, revision, buildno, builddate, compiler)
    _sys_version_cache[sys_version] = result
    return result

def python_implementation():

    """ Returns a string identifying the Python implementation.

        Currently, the following implementations are identified:
        'CPython' (C implementation of Python),
        'IronPython' (.NET implementation of Python),
        'Jython' (Java implementation of Python).

    """
    return _sys_version()[0]

def python_version():

    """ Returns the Python version as string 'major.minor.patchlevel'

        Note that unlike the Python sys.version, the returned value
        will always include the patchlevel (it defaults to 0).

    """
    return _sys_version()[1]

def python_version_tuple():

    """ Returns the Python version as tuple (major, minor, patchlevel)
        of strings.

        Note that unlike the Python sys.version, the returned value
        will always include the patchlevel (it defaults to 0).

    """
    return tuple(_sys_version()[1].split('.'))

def python_branch():

    """ Returns a string identifying the Python implementation
        branch.

        For CPython this is the Subversion branch from which the
        Python binary was built.

        If not available, an empty string is returned.

    """

    return _sys_version()[2]

def python_revision():

    """ Returns a string identifying the Python implementation
        revision.

        For CPython this is the Subversion revision from which the
        Python binary was built.

        If not available, an empty string is returned.

    """
    return _sys_version()[3]

def python_build():

    """ Returns a tuple (buildno, builddate) stating the Python
        build number and date as strings.

    """
    return _sys_version()[4:6]

def python_compiler():

    """ Returns a string identifying the compiler used for compiling
        Python.

    """
    return _sys_version()[6]

### The Opus Magnum of platform strings :-)

_platform_cache = {}

def platform(aliased=0, terse=0):

    """ Returns a single string identifying the underlying platform
        with as much useful information as possible (but no more :).

        The output is intended to be human readable rather than
        machine parseable. It may look different on different
        platforms and this is intended.

        If "aliased" is true, the function will use aliases for
        various platforms that report system names which differ from
        their common names, e.g. SunOS will be reported as
        Solaris. The system_alias() function is used to implement
        this.

        Setting terse to true causes the function to return only the
        absolute minimum information needed to identify the platform.

    """
    result = _platform_cache.get((aliased, terse), None)
    if result is not None:
        return result

    # Get uname information and then apply platform specific cosmetics
    # to it...
    system,node,release,version,machine,processor = uname()
    if machine == processor:
        processor = ''
    if aliased:
        system,release,version = system_alias(system,release,version)

    if system == 'Windows':
        # MS platforms
        rel,vers,csd,ptype = win32_ver(version)
        if terse:
            platform = _platform(system,release)
        else:
            platform = _platform(system,release,version,csd)

    elif system in ('Linux',):
        # Linux based systems
        distname,distversion,distid = dist('')
        if distname and not terse:
            platform = _platform(system,release,machine,processor,
                                 'with',
                                 distname,distversion,distid)
        else:
            # If the distribution name is unknown check for libc vs. glibc
            libcname,libcversion = libc_ver(sys.executable)
            platform = _platform(system,release,machine,processor,
                                 'with',
                                 libcname+libcversion)
    elif system == 'Java':
        # Java platforms
        r,v,vminfo,(os_name,os_version,os_arch) = java_ver()
        if terse or not os_name:
            platform = _platform(system,release,version)
        else:
            platform = _platform(system,release,version,
                                 'on',
                                 os_name,os_version,os_arch)

    elif system == 'MacOS':
        # MacOS platforms
        if terse:
            platform = _platform(system,release)
        else:
            platform = _platform(system,release,machine)

    else:
        # Generic handler
        if terse:
            platform = _platform(system,release)
        else:
            bits,linkage = architecture(sys.executable)
            platform = _platform(system,release,machine,processor,bits,linkage)

    _platform_cache[(aliased, terse)] = platform
    return platform

### Command line interface

if __name__ == '__main__':
    # Default is to print the aliased verbose platform string
    terse = ('terse' in sys.argv or '--terse' in sys.argv)
    aliased = (not 'nonaliased' in sys.argv and not '--nonaliased' in sys.argv)
    print(platform(aliased,terse))
    sys.exit(0)