This file is indexed.

/usr/lib/python2.7/dist-packages/fuse.py is in python-fuse 2:0.2.1-16.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   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
#
#    Copyright (C) 2001  Jeff Epler  <jepler@unpythonic.dhs.org>
#    Copyright (C) 2006  Csaba Henk  <csaba.henk@creo.hu>
#
#    This program can be distributed under the terms of the GNU LGPL.
#    See the file COPYING.
#


# suppress version mismatch warnings
try:
    import warnings
    warnings.filterwarnings('ignore',
                            'Python C API version mismatch',
                            RuntimeWarning,
                            )
except:
    pass

from string import join
import sys
import os
from errno import *
from os import environ
import re
from fuseparts import __version__
from fuseparts._fuse import main, FuseGetContext, FuseInvalidate
from fuseparts._fuse import FuseError, FuseAPIVersion
from fuseparts.subbedopts import SubOptsHive, SubbedOptFormatter
from fuseparts.subbedopts import SubbedOptIndentedFormatter, SubbedOptParse
from fuseparts.subbedopts import SUPPRESS_HELP, OptParseError
from fuseparts.setcompatwrap import set


##########
###
###  API specification API.
###
##########

# The actual API version of this module
FUSE_PYTHON_API_VERSION = (0, 2)

def __getenv__(var, pattern = '.', trans = lambda x: x):
    """
    Fetch enviroment variable and optionally transform it. Return `None` if
    variable is unset. Bail out if value of variable doesn't match (optional)
    regex pattern.
    """

    if var not in environ:
        return None
    val = environ[var]
    rpat = pattern
    if not isinstance(rpat, type(re.compile(''))):
        rpat = re.compile(rpat)
    if not rpat.search(val):
        raise RuntimeError("env var %s doesn't match required pattern %s" % \
                           (var, `pattern`))
    return trans(val)

def get_fuse_python_api():
    if fuse_python_api:
        return fuse_python_api
    elif compat_0_1:
        # deprecated way of API specification
        return (0,1)

def get_compat_0_1():
    return get_fuse_python_api() == (0, 1)

# API version to be used
fuse_python_api = __getenv__('FUSE_PYTHON_API', '^[\d.]+$',
                              lambda x: tuple([int(i) for i in x.split('.')]))

# deprecated way of API specification
compat_0_1 = __getenv__('FUSE_PYTHON_COMPAT', '^(0.1|ALL)$', lambda x: True)

fuse_python_api = get_fuse_python_api()

##########
###
###  Parsing for FUSE.
###
##########



class FuseArgs(SubOptsHive):
    """
    Class representing a FUSE command line.
    """

    fuse_modifiers = {'showhelp': '-ho',
                      'showversion': '-V',
                      'foreground': '-f'}

    def __init__(self):

        SubOptsHive.__init__(self)

        self.modifiers = {}
        self.mountpoint = None

        for m in self.fuse_modifiers:
            self.modifiers[m] = False

    def __str__(self):
        return '\n'.join(['< on ' + str(self.mountpoint) + ':',
                          '  ' + str(self.modifiers), '  -o ']) + \
               ',\n     '.join(self._str_core()) + \
               ' >'

    def getmod(self, mod):
        return self.modifiers[mod]

    def setmod(self, mod):
        self.modifiers[mod] = True

    def unsetmod(self, mod):
        self.modifiers[mod] = False

    def mount_expected(self):
        if self.getmod('showhelp'):
            return False
        if self.getmod('showversion'):
            return False
        return True

    def assemble(self):
        """Mangle self into an argument array"""

        self.canonify()
        args = [sys.argv and sys.argv[0] or "python"]
        if self.mountpoint:
            args.append(self.mountpoint)
        for m, v in self.modifiers.iteritems():
            if v:
                args.append(self.fuse_modifiers[m])

        opta = []
        for o, v in self.optdict.iteritems():
                opta.append(o + '=' + v)
        opta.extend(self.optlist)

        if opta:
            args.append("-o" + ",".join(opta))

        return args

    def filter(self, other=None):
        """
        Same as for SubOptsHive, with the following difference:
        if other is not specified, `Fuse.fuseoptref()` is run and its result
        will be used.
        """

        if not other:
            other = Fuse.fuseoptref()

        return SubOptsHive.filter(self, other)



class FuseFormatter(SubbedOptIndentedFormatter):

    def __init__(self, **kw):
        if not 'indent_increment' in kw:
            kw['indent_increment'] = 4
        SubbedOptIndentedFormatter.__init__(self, **kw)

    def store_option_strings(self, parser):
        SubbedOptIndentedFormatter.store_option_strings(self, parser)
        # 27 is how the lib stock help appears
        self.help_position = max(self.help_position, 27)
        self.help_width = self.width - self.help_position


class FuseOptParse(SubbedOptParse):
    """
    This class alters / enhances `SubbedOptParse` so that it's
    suitable for usage with FUSE.

    - When adding options, you can use the `mountopt` pseudo-attribute which
      is equivalent with adding a subopt for option ``-o``
      (it doesn't require an option argument).

    - FUSE compatible help and version printing.

    - Error and exit callbacks are relaxed. In case of FUSE, the command
      line is to be treated as a DSL [#]_. You don't wanna this module to
      force an exit on you just because you hit a DSL syntax error.

    - Built-in support for conventional FUSE options (``-d``, ``-f`, ``-s``).
      The way of this can be tuned by keyword arguments, see below.

    .. [#] http://en.wikipedia.org/wiki/Domain-specific_programming_language

    Keyword arguments for initialization
    ------------------------------------

    standard_mods
      Boolean [default is `True`].
      Enables support for the usual interpretation of the ``-d``, ``-f``
      options.

    fetch_mp
      Boolean [default is `True`].
      If it's True, then the last (non-option) argument
      (if there is such a thing) will be used as the FUSE mountpoint.

    dash_s_do
      String: ``whine``, ``undef``, or ``setsingle`` [default is ``whine``].
      The ``-s`` option -- traditionally for asking for single-threadedness --
      is an oddball: single/multi threadedness of a fuse-py fs doesn't depend
      on the FUSE command line, we have direct control over it.

      Therefore we have two conflicting principles:

      - *Orthogonality*: option parsing shouldn't affect the backing `Fuse`
        instance directly, only via its `fuse_args` attribute.

      - *POLS*: behave like other FUSE based fs-es do. The stock FUSE help
        makes mention of ``-s`` as a single-threadedness setter.

      So, if we follow POLS and implement a conventional ``-s`` option, then
      we have to go beyond the `fuse_args` attribute and set the respective
      Fuse attribute directly, hence violating orthogonality.

      We let the fs authors make their choice: ``dash_s_do=undef`` leaves this
      option unhandled, and the fs author can add a handler as she desires.
      ``dash_s_do=setsingle`` enables the traditional behaviour.

      Using ``dash_s_do=setsingle`` is not problematic at all, but we want fs
      authors be aware of the particularity of ``-s``, therefore the default is
      the ``dash_s_do=whine`` setting which raises an exception for ``-s`` and
      suggests the user to read this documentation.

    dash_o_handler
      Argument should be a SubbedOpt instance (created with
      ``action="store_hive"`` if you want it to be useful).
      This lets you customize the handler of the ``-o`` option. For example,
      you can alter or suppress the generic ``-o`` entry in help output.
    """

    def __init__(self, *args, **kw):

        self.mountopts = []

        self.fuse_args = \
            'fuse_args' in kw and kw.pop('fuse_args') or FuseArgs()
        dsd = 'dash_s_do' in kw and kw.pop('dash_s_do') or 'whine'
        if 'fetch_mp' in kw:
            self.fetch_mp = bool(kw.pop('fetch_mp'))
        else:
            self.fetch_mp = True
        if 'standard_mods' in kw:
            smods = bool(kw.pop('standard_mods'))
        else:
            smods = True
        if 'fuse' in kw:
            self.fuse = kw.pop('fuse')
        if not 'formatter' in kw:
            kw['formatter'] = FuseFormatter()
        doh = 'dash_o_handler' in kw and kw.pop('dash_o_handler')

        SubbedOptParse.__init__(self, *args, **kw)

        if doh:
            self.add_option(doh)
        else:
            self.add_option('-o', action='store_hive',
                            subopts_hive=self.fuse_args, help="mount options",
                            metavar="opt,[opt...]")

        if smods:
            self.add_option('-f', action='callback',
                            callback=lambda *a: self.fuse_args.setmod('foreground'),
                            help=SUPPRESS_HELP)
            self.add_option('-d', action='callback',
                            callback=lambda *a: self.fuse_args.add('debug'),
                            help=SUPPRESS_HELP)

        if dsd == 'whine':
            def dsdcb(option, opt_str, value, parser):
                raise RuntimeError, """

! If you want the "-s" option to work, pass
!
!   dash_s_do='setsingle'
!
! to the Fuse constructor. See docstring of the FuseOptParse class for an
! explanation why is it not set by default.
"""

        elif dsd == 'setsingle':
            def dsdcb(option, opt_str, value, parser):
                self.fuse.multithreaded = False

        elif dsd == 'undef':
            dsdcb = None
        else:
            raise ArgumentError, "key `dash_s_do': uninterpreted value " + str(dsd)

        if dsdcb:
            self.add_option('-s', action='callback', callback=dsdcb,
                            help=SUPPRESS_HELP)


    def exit(self, status=0, msg=None):
        if msg:
            sys.stderr.write(msg)

    def error(self, msg):
        SubbedOptParse.error(self, msg)
        raise OptParseError, msg

    def print_help(self, file=sys.stderr):
        SubbedOptParse.print_help(self, file)
        print >> file
        self.fuse_args.setmod('showhelp')

    def print_version(self, file=sys.stderr):
        SubbedOptParse.print_version(self, file)
        self.fuse_args.setmod('showversion')

    def parse_args(self, args=None, values=None):
        o, a = SubbedOptParse.parse_args(self, args, values)
        if a and self.fetch_mp:
            self.fuse_args.mountpoint = os.path.realpath(a.pop())
        return o, a

    def add_option(self, *opts, **attrs):
        if 'mountopt' in attrs:
            if opts or 'subopt' in attrs:
                raise OptParseError(
                  "having options or specifying the `subopt' attribute conflicts with `mountopt' attribute")
            opts = ('-o',)
            attrs['subopt'] = attrs.pop('mountopt')
            if not 'dest' in attrs:
                attrs['dest'] = attrs['subopt']

        SubbedOptParse.add_option(self, *opts, **attrs)



##########
###
###  The FUSE interface.
###
##########



class ErrnoWrapper(object):

    def __init__(self, func):
        self.func = func

    def __call__(self, *args, **kw):
        try:
            return apply(self.func, args, kw)
        except (IOError, OSError), detail:
            # Sometimes this is an int, sometimes an instance...
            if hasattr(detail, "errno"): detail = detail.errno
            return -detail


########### Custom objects for transmitting system structures to FUSE

class FuseStruct(object):

    def __init__(self, **kw):
        for k in kw:
             setattr(self, k, kw[k])


class Stat(FuseStruct):
    """
    Auxiliary class which can be filled up stat attributes.
    The attributes are undefined by default.
    """

    def __init__(self, **kw):
        self.st_mode  = None
        self.st_ino   = 0
        self.st_dev   = 0
        self.st_nlink = None
        self.st_uid   = 0
        self.st_gid   = 0
        self.st_size  = 0
        self.st_atime = 0
        self.st_mtime = 0
        self.st_ctime = 0

        FuseStruct.__init__(self, **kw)


class StatVfs(FuseStruct):
    """
    Auxiliary class which can be filled up statvfs attributes.
    The attributes are 0 by default.
    """

    def __init__(self, **kw):

        self.f_bsize   = 0
        self.f_frsize  = 0
        self.f_blocks  = 0
        self.f_bfree   = 0
        self.f_bavail  = 0
        self.f_files   = 0
        self.f_ffree   = 0
        self.f_favail  = 0
        self.f_flag    = 0
        self.f_namemax = 0

        FuseStruct.__init__(self, **kw)


class Direntry(FuseStruct):
    """
    Auxiliary class for carrying directory entry data.
    Initialized with `name`. Further attributes (each
    set to 0 as default):

    offset
        An integer (or long) parameter, used as a bookmark
        during directory traversal.
        This needs to be set it you want stateful directory
        reading.

    type
       Directory entry type, should be one of the stat type
       specifiers (stat.S_IFLNK, stat.S_IFBLK, stat.S_IFDIR,
       stat.S_IFCHR, stat.S_IFREG, stat.S_IFIFO, stat.S_IFSOCK).

    ino
       Directory entry inode number.

    Note that Python's standard directory reading interface is
    stateless and provides only names, so the above optional
    attributes doesn't make sense in that context.
    """

    def __init__(self, name, **kw):

        self.name   = name
        self.offset = 0
        self.type   = 0
        self.ino    = 0

        FuseStruct.__init__(self, **kw)


class Flock(FuseStruct):
    """
    Class for representing flock structures (cf. fcntl(3)).
    
    It makes sense to give values to the `l_type`, `l_start`,
    `l_len`, `l_pid` attributes (`l_whence` is not used by
    FUSE, see ``fuse.h``).
    """

    def __init__(self, name=None, **kw):
    
        self.l_type  = None
        self.l_start = None
        self.l_len   = None
        self.l_pid   = None
 
        kw['name'] = name
        FuseStruct.__init__(self, **kw)

 
class Timespec(FuseStruct):
    """
    Cf. struct timespec in time.h:
    http://www.opengroup.org/onlinepubs/009695399/basedefs/time.h.html
    """

    def __init__(self, name=None, **kw):
    
        self.tv_sec  = None
        self.tv_nsec = None
 
        kw['name'] = name
        FuseStruct.__init__(self, **kw)


class FuseFileInfo(FuseStruct):

    def __init__(self, **kw):

        self.keep      = False
        self.direct_io = False

        FuseStruct.__init__(self, **kw)



########## Interface for requiring certain features from your underlying FUSE library.

def feature_needs(*feas):
    """
    Get info about the FUSE API version needed for the support of some features.

    This function takes a variable number of feature patterns.

    A feature pattern is either:

    -  an integer (directly referring to a FUSE API version number)
    -  a built-in feature specifier string (meaning defined by dictionary)
    -  a string of the form ``has_foo``, where ``foo`` is a filesystem method
       (refers to the API version where the method has been introduced)
    -  a list/tuple of other feature patterns (matches each of its members)
    -  a regexp (meant to be matched against the builtins plus ``has_foo``
       patterns; can also be given by a string of the from "re:*")
    -  a negated regexp (can be given by a string of the form "!re:*")

    If called with no arguments, then the list of builtins is returned, mapped
    to their meaning.

    Otherwise the function returns the smallest FUSE API version number which
    has all the matching features.

    Builtin specifiers worth to explicit mention:
    - ``stateful_files``: you want to use custom filehandles (eg. a file class).
    - ``*``: you want all features.
    - while ``has_foo`` makes sense for all filesystem method ``foo``, some
      of these can be found among the builtins, too (the ones which can be
      handled by the general rule).

    specifiers like ``has_foo`` refer to requirement that the library knows of
      the fs method ``foo``.
    """

    fmap = {'stateful_files': 22,
            'stateful_dirs':  23,
            'stateful_io':    ('stateful_files', 'stateful_dirs'),
            'stateful_files_keep_cache': 23,
            'stateful_files_direct_io': 23,
            'keep_cache':     ('stateful_files_keep_cache',),
            'direct_io':      ('stateful_files_direct_io',),
            'has_opendir':    ('stateful_dirs',),
            'has_releasedir': ('stateful_dirs',),
            'has_fsyncdir':   ('stateful_dirs',),
            'has_create':     25,
            'has_access':     25,
            'has_fgetattr':   25,
            'has_ftruncate':  25,
            'has_fsinit':     ('has_init'),
            'has_fsdestroy':  ('has_destroy'),
            'has_lock':       26,
            'has_utimens':    26,
            'has_bmap':       26,
            'has_init':       23,
            'has_destroy':    23,
            '*':              '!re:^\*$'}

    if not feas:
        return fmap

    def resolve(args, maxva):

        for fp in args:
            if isinstance(fp, int):
                maxva[0] = max(maxva[0], fp)
                continue
            if isinstance(fp, list) or isinstance(fp, tuple):
                for f in fp:
                    yield f
                continue
            ma = isinstance(fp, str) and re.compile("(!\s*|)re:(.*)").match(fp)
            if isinstance(fp, type(re.compile(''))) or ma:
                neg = False
                if ma:
                    mag = ma.groups()
                    fp = re.compile(mag[1])
                    neg = bool(mag[0])
                for f in fmap.keys() + [ 'has_' + a for a in Fuse._attrs ]:
                    if neg != bool(re.search(fp, f)):
                        yield f
                continue
            ma = re.compile("has_(.*)").match(fp)
            if ma and ma.groups()[0] in Fuse._attrs and not fp in fmap:
                yield 21
                continue
            yield fmap[fp]

    maxva = [0]
    while feas:
        feas = set(resolve(feas, maxva))

    return maxva[0]


def APIVersion():
    """Get the API version of your underlying FUSE lib"""

    return FuseAPIVersion()


def feature_assert(*feas):
    """
    Takes some feature patterns (like in `feature_needs`).
    Raises a fuse.FuseError if your underlying FUSE lib fails
    to have some of the matching features.

    (Note: use a ``has_foo`` type feature assertion only if lib support
    for method ``foo`` is *necessary* for your fs. Don't use this assertion
    just because your fs implements ``foo``. The usefulness of ``has_foo``
    is limited by the fact that we can't guarantee that your FUSE kernel
    module also supports ``foo``.)
    """

    fav = APIVersion()

    for fea in feas:
        fn = feature_needs(fea)
        if fav < fn:
            raise FuseError(
              "FUSE API version %d is required for feature `%s' but only %d is available" % \
              (fn, str(fea), fav))


############# Subclass this.

class Fuse(object):
    """
    Python interface to FUSE.

    Basic usage:

    - instantiate

    - add options to `parser` attribute (an instance of `FuseOptParse`)

    - call `parse`

    - call `main`
    """

    _attrs = ['getattr', 'readlink', 'readdir', 'mknod', 'mkdir',
              'unlink', 'rmdir', 'symlink', 'rename', 'link', 'chmod',
              'chown', 'truncate', 'utime', 'open', 'read', 'write', 'release',
              'statfs', 'fsync', 'create', 'opendir', 'releasedir', 'fsyncdir',
              'flush', 'fgetattr', 'ftruncate', 'getxattr', 'listxattr',
              'setxattr', 'removexattr', 'access', 'lock', 'utimens', 'bmap',
              'fsinit', 'fsdestroy']

    fusage = "%prog [mountpoint] [options]"

    def __init__(self, *args, **kw):
        """
        Not much happens here apart from initializing the `parser` attribute.
        Arguments are forwarded to the constructor of the parser class almost
        unchanged.

        The parser class is `FuseOptParse` unless you specify one using the
        ``parser_class`` keyword. (See `FuseOptParse` documentation for
        available options.)
        """

        if not fuse_python_api:
            raise RuntimeError, __name__ + """.fuse_python_api not defined.

! Please define """ + __name__ + """.fuse_python_api internally (eg.
! 
! (1)  """ + __name__ + """.fuse_python_api = """ + `FUSE_PYTHON_API_VERSION` + """
! 
! ) or in the enviroment (eg. 
! 
! (2)  FUSE_PYTHON_API=0.1
! 
! ).
!
! If you are actually developing a filesystem, probably (1) is the way to go.
! If you are using a filesystem written before 2007 Q2, probably (2) is what
! you want."
"""

        def malformed():
            raise RuntimeError, \
                  "malformatted fuse_python_api value " + `fuse_python_api`
        if not isinstance(fuse_python_api, tuple):
            malformed()
        for i in fuse_python_api:
            if not isinstance(i, int) or i < 0:
                malformed() 

        if fuse_python_api > FUSE_PYTHON_API_VERSION:
            raise RuntimeError, """
! You require FUSE-Python API version """ + `fuse_python_api` + """.
! However, the latest available is """ + `FUSE_PYTHON_API_VERSION` + """.
"""

        self.fuse_args = \
            'fuse_args' in kw and kw.pop('fuse_args') or FuseArgs()

        if get_compat_0_1():
            return self.__init_0_1__(*args, **kw)

        self.multithreaded = True

        if not 'usage' in kw:
            kw['usage'] = self.fusage
        if not 'fuse_args' in kw:
            kw['fuse_args'] = self.fuse_args
        kw['fuse'] = self
        parserclass = \
          'parser_class' in kw and kw.pop('parser_class') or FuseOptParse

        self.parser = parserclass(*args, **kw)
        self.methproxy = self.Methproxy()

    def parse(self, *args, **kw):
        """Parse command line, fill `fuse_args` attribute."""

        ev = 'errex' in kw and kw.pop('errex')
        if ev and not isinstance(ev, int):
            raise TypeError, "error exit value should be an integer"

        try:
            self.cmdline = self.parser.parse_args(*args, **kw)
        except OptParseError:
          if ev:
              sys.exit(ev)
          raise

        return self.fuse_args

    def main(self, args=None):
        """Enter filesystem service loop."""

        if get_compat_0_1():
            args = self.main_0_1_preamble()

        d = {'multithreaded': self.multithreaded and 1 or 0}
        d['fuse_args'] = args or self.fuse_args.assemble()

        for t in 'file_class', 'dir_class':
            if hasattr(self, t):
                getattr(self.methproxy, 'set_' + t)(getattr(self,t))

        for a in self._attrs:
            b = a
            if get_compat_0_1() and a in self.compatmap:
                b = self.compatmap[a]
            if hasattr(self, b):
                c = ''
                if get_compat_0_1() and hasattr(self, a + '_compat_0_1'):
                    c = '_compat_0_1'
                d[a] = ErrnoWrapper(self.lowwrap(a + c))

        try:
            main(**d)
        except FuseError:
            if args or self.fuse_args.mount_expected():
                raise

    def lowwrap(self, fname):
        """
        Wraps the fname method when the C code expects a different kind of
        callback than we have in the fusepy API. (The wrapper is usually for
        performing some checks or transfromations which could be done in C but
        is simpler if done in Python.)

        Currently `open` and `create` are wrapped: a boolean flag is added
        which indicates if the result is to be kept during the opened file's
        lifetime or can be thrown away. Namely, it's considered disposable
        if it's an instance of FuseFileInfo.
        """
        fun = getattr(self, fname)

        if fname in ('open', 'create'):
            def wrap(*a, **kw):
                res = fun(*a, **kw)
                if not res or type(res) == type(0):
                    return res
                else:
                    return (res, type(res) != FuseFileInfo)
        elif fname == 'utimens':
            def wrap(path, acc_sec, acc_nsec, mod_sec, mod_nsec):
                ts_acc = Timespec(tv_sec = acc_sec, tv_nsec = acc_nsec)
                ts_mod = Timespec(tv_sec = mod_sec, tv_nsec = mod_nsec)
                return fun(path, ts_acc, ts_mod)
        else:
            wrap = fun

        return wrap

    def GetContext(self):
        return FuseGetContext(self)

    def Invalidate(self, path):
        return FuseInvalidate(self, path)

    def fuseoptref(cls):
        """
        Find out which options are recognized by the library.
        Result is a `FuseArgs` instance with the list of supported
        options, suitable for passing on to the `filter` method of
        another `FuseArgs` instance.
        """

        import os, re

        pr, pw = os.pipe()
        pid = os.fork()
        if pid == 0:
             os.dup2(pw, 2)
             os.close(pr)

             fh = cls()
             fh.fuse_args = FuseArgs()
             fh.fuse_args.setmod('showhelp')
             fh.main()
             sys.exit()

        os.close(pw)

        fa = FuseArgs()
        ore = re.compile("-o\s+([\w\[\]]+(?:=\w+)?)")
        fpr = os.fdopen(pr)
        for l in fpr:
             m = ore.search(l)
             if m:
                 o = m.groups()[0]
                 oa = [o]
                 # try to catch two-in-one options (like "[no]foo")
                 opa = o.split("[")
                 if len(opa) == 2:
                    o1, ox = opa
                    oxpa = ox.split("]")
                    if len(oxpa) == 2:
                       oo, o2 = oxpa
                       oa = [o1 + o2, o1 + oo + o2]
                 for o in oa:
                     fa.add(o)

        fpr.close()
        return fa

    fuseoptref = classmethod(fuseoptref)


    class Methproxy(object):

        def __init__(self):

            class mpx(object):
               def __init__(self, name):
                   self.name = name
               def __call__(self, *a, **kw):
                   return getattr(a[-1], self.name)(*(a[1:-1]), **kw)

            self.proxyclass = mpx
            self.mdic = {}
            self.file_class = None
            self.dir_class = None

        def __call__(self, meth):
            return meth in self.mdic and self.mdic[meth] or None

        def _add_class_type(cls, type, inits, proxied):

            def setter(self, xcls):

                setattr(self, type + '_class', xcls)

                for m in inits:
                    self.mdic[m] = xcls

                for m in proxied:
                    if hasattr(xcls, m):
                        self.mdic[m] = self.proxyclass(m)

            setattr(cls, 'set_' + type + '_class', setter)

        _add_class_type = classmethod(_add_class_type)

    Methproxy._add_class_type('file', ('open', 'create'),
                              ('read', 'write', 'fsync', 'release', 'flush',
                               'fgetattr', 'ftruncate', 'lock'))
    Methproxy._add_class_type('dir', ('opendir',),
                              ('readdir', 'fsyncdir', 'releasedir'))


    def __getattr__(self, meth):

        m = self.methproxy(meth)
        if m:
            return m

        raise AttributeError, "Fuse instance has no attribute '%s'" % meth



##########
###
###  Compat stuff.
###
##########



    def __init_0_1__(self, *args, **kw):

        self.flags = 0
        multithreaded = 0

        # default attributes
        if args == ():
            # there is a self.optlist.append() later on, make sure it won't
            # bomb out.
            self.optlist = []
        else:
            self.optlist = args
        self.optdict = kw

        if len(self.optlist) == 1:
            self.mountpoint = self.optlist[0]
        else:
            self.mountpoint = None

        # grab command-line arguments, if any.
        # Those will override whatever parameters
        # were passed to __init__ directly.
        argv = sys.argv
        argc = len(argv)
        if argc > 1:
            # we've been given the mountpoint
            self.mountpoint = argv[1]
        if argc > 2:
            # we've received mount args
            optstr = argv[2]
            opts = optstr.split(",")
            for o in opts:
                try:
                    k, v = o.split("=", 1)
                    self.optdict[k] = v
                except:
                    self.optlist.append(o)


    def main_0_1_preamble(self):

        cfargs = FuseArgs()

        cfargs.mountpoint = self.mountpoint

        if hasattr(self, 'debug'):
            cfargs.add('debug')

        if hasattr(self, 'allow_other'):
            cfargs.add('allow_other')

        if hasattr(self, 'kernel_cache'):
            cfargs.add('kernel_cache')

        return cfargs.assemble()


    def getattr_compat_0_1(self, *a):
        from os import stat_result

        return stat_result(self.getattr(*a))


    def statfs_compat_0_1(self, *a):

        oout = self.statfs(*a)
        lo = len(oout)

        svf = StatVfs()
        svf.f_bsize   = oout[0]                   # 0
        svf.f_frsize  = oout[lo >= 8 and 7 or 0]  # 1
        svf.f_blocks  = oout[1]                   # 2
        svf.f_bfree   = oout[2]                   # 3
        svf.f_bavail  = oout[3]                   # 4
        svf.f_files   = oout[4]                   # 5
        svf.f_ffree   = oout[5]                   # 6
        svf.f_favail  = lo >= 9 and oout[8] or 0  # 7
        svf.f_flag    = lo >= 10 and oout[9] or 0 # 8
        svf.f_namemax = oout[6]                   # 9

        return svf


    def readdir_compat_0_1(self, path, offset, *fh):

        for name, type in self.getdir(path):
            de = Direntry(name)
            de.type = type

            yield de


    compatmap = {'readdir': 'getdir'}