summaryrefslogtreecommitdiffstats
path: root/Lib/os.py
blob: 5ee3d4bc7caf1bba12216f0c64fbda326f1bd7a9 (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
r"""OS routines for Mac, NT, or Posix depending on what system we're on.

This exports:
  - all functions from posix, nt, os2, mac, or ce, e.g. unlink, stat, etc.
  - os.path is one of the modules posixpath, ntpath, or macpath
  - os.name is 'posix', 'nt', 'os2', 'mac', 'ce' or 'riscos'
  - os.curdir is a string representing the current directory ('.' or ':')
  - os.pardir is a string representing the parent directory ('..' or '::')
  - os.sep is the (or a most common) pathname separator ('/' or ':' or '\\')
  - os.extsep is the extension separator ('.' or '/')
  - os.altsep is the alternate pathname separator (None or '/')
  - os.pathsep is the component separator used in $PATH etc
  - os.linesep is the line separator in text files ('\r' or '\n' or '\r\n')
  - os.defpath is the default search path for executables
  - os.devnull is the file path of the null device ('/dev/null', etc.)

Programs that import and use 'os' stand a better chance of being
portable between different platforms.  Of course, they must then
only use functions that are defined by all platforms (e.g., unlink
and opendir), and leave all pathname manipulation to os.path
(e.g., split and join).
"""

#'

import sys

_names = sys.builtin_module_names

# Note:  more names are added to __all__ later.
__all__ = ["altsep", "curdir", "pardir", "sep", "pathsep", "linesep",
           "defpath", "name", "path", "devnull",
           "SEEK_SET", "SEEK_CUR", "SEEK_END"]

def _get_exports_list(module):
    try:
        return list(module.__all__)
    except AttributeError:
        return [n for n in dir(module) if n[0] != '_']

if 'posix' in _names:
    name = 'posix'
    linesep = '\n'
    from posix import *
    try:
        from posix import _exit
    except ImportError:
        pass
    import posixpath as path

    import posix
    __all__.extend(_get_exports_list(posix))
    del posix

elif 'nt' in _names:
    name = 'nt'
    linesep = '\r\n'
    from nt import *
    try:
        from nt import _exit
    except ImportError:
        pass
    import ntpath as path

    import nt
    __all__.extend(_get_exports_list(nt))
    del nt

elif 'os2' in _names:
    name = 'os2'
    linesep = '\r\n'
    from os2 import *
    try:
        from os2 import _exit
    except ImportError:
        pass
    if sys.version.find('EMX GCC') == -1:
        import ntpath as path
    else:
        import os2emxpath as path
        from _emx_link import link

    import os2
    __all__.extend(_get_exports_list(os2))
    del os2

elif 'mac' in _names:
    name = 'mac'
    linesep = '\r'
    from mac import *
    try:
        from mac import _exit
    except ImportError:
        pass
    import macpath as path

    import mac
    __all__.extend(_get_exports_list(mac))
    del mac

elif 'ce' in _names:
    name = 'ce'
    linesep = '\r\n'
    from ce import *
    try:
        from ce import _exit
    except ImportError:
        pass
    # We can use the standard Windows path.
    import ntpath as path

    import ce
    __all__.extend(_get_exports_list(ce))
    del ce

elif 'riscos' in _names:
    name = 'riscos'
    linesep = '\n'
    from riscos import *
    try:
        from riscos import _exit
    except ImportError:
        pass
    import riscospath as path

    import riscos
    __all__.extend(_get_exports_list(riscos))
    del riscos

else:
    raise ImportError, 'no os specific module found'

sys.modules['os.path'] = path
from os.path import (curdir, pardir, sep, pathsep, defpath, extsep, altsep,
    devnull)

del _names

# Python uses fixed values for the SEEK_ constants; they are mapped
# to native constants if necessary in posixmodule.c
SEEK_SET = 0
SEEK_CUR = 1
SEEK_END = 2

#'

# Super directory utilities.
# (Inspired by Eric Raymond; the doc strings are mostly his)

def makedirs(name, mode=0777):
    """makedirs(path [, mode=0777])

    Super-mkdir; create a leaf directory and all intermediate ones.
    Works like mkdir, except that any intermediate path segment (not
    just the rightmost) will be created if it does not exist.  This is
    recursive.

    """
    head, tail = path.split(name)
    if not tail:
        head, tail = path.split(head)
    if head and tail and not path.exists(head):
        makedirs(head, mode)
        if tail == curdir:           # xxx/newdir/. exists if xxx/newdir exists
            return
    mkdir(name, mode)

def removedirs(name):
    """removedirs(path)

    Super-rmdir; remove a leaf directory and all empty intermediate
    ones.  Works like rmdir except that, if the leaf directory is
    successfully removed, directories corresponding to rightmost path
    segments will be pruned away until either the whole path is
    consumed or an error occurs.  Errors during this latter phase are
    ignored -- they generally mean that a directory was not empty.

    """
    rmdir(name)
    head, tail = path.split(name)
    if not tail:
        head, tail = path.split(head)
    while head and tail:
        try:
            rmdir(head)
        except error:
            break
        head, tail = path.split(head)

def renames(old, new):
    """renames(old, new)

    Super-rename; create directories as necessary and delete any left
    empty.  Works like rename, except creation of any intermediate
    directories needed to make the new pathname good is attempted
    first.  After the rename, directories corresponding to rightmost
    path segments of the old name will be pruned way until either the
    whole path is consumed or a nonempty directory is found.

    Note: this function can fail with the new directory structure made
    if you lack permissions needed to unlink the leaf directory or
    file.

    """
    head, tail = path.split(new)
    if head and tail and not path.exists(head):
        makedirs(head)
    rename(old, new)
    head, tail = path.split(old)
    if head and tail:
        try:
            removedirs(head)
        except error:
            pass

__all__.extend(["makedirs", "removedirs", "renames"])

def walk(top, topdown=True, onerror=None):
    """Directory tree generator.

    For each directory in the directory tree rooted at top (including top
    itself, but excluding '.' and '..'), yields a 3-tuple

        dirpath, dirnames, filenames

    dirpath is a string, the path to the directory.  dirnames is a list of
    the names of the subdirectories in dirpath (excluding '.' and '..').
    filenames is a list of the names of the non-directory files in dirpath.
    Note that the names in the lists are just names, with no path components.
    To get a full path (which begins with top) to a file or directory in
    dirpath, do os.path.join(dirpath, name).

    If optional arg 'topdown' is true or not specified, the triple for a
    directory is generated before the triples for any of its subdirectories
    (directories are generated top down).  If topdown is false, the triple
    for a directory is generated after the triples for all of its
    subdirectories (directories are generated bottom up).

    When topdown is true, the caller can modify the dirnames list in-place
    (e.g., via del or slice assignment), and walk will only recurse into the
    subdirectories whose names remain in dirnames; this can be used to prune
    the search, or to impose a specific order of visiting.  Modifying
    dirnames when topdown is false is ineffective, since the directories in
    dirnames have already been generated by the time dirnames itself is
    generated.

    By default errors from the os.listdir() call are ignored.  If
    optional arg 'onerror' is specified, it should be a function; it
    will be called with one argument, an os.error instance.  It can
    report the error to continue with the walk, or raise the exception
    to abort the walk.  Note that the filename is available as the
    filename attribute of the exception object.

    Caution:  if you pass a relative pathname for top, don't change the
    current working directory between resumptions of walk.  walk never
    changes the current directory, and assumes that the client doesn't
    either.

    Example:

    from os.path import join, getsize
    for root, dirs, files in walk('python/Lib/email'):
        print root, "consumes",
        print sum([getsize(join(root, name)) for name in files]),
        print "bytes in", len(files), "non-directory files"
        if 'CVS' in dirs:
            dirs.remove('CVS')  # don't visit CVS directories
    """

    from os.path import join, isdir, islink

    # We may not have read permission for top, in which case we can't
    # get a list of the files the directory contains.  os.path.walk
    # always suppressed the exception then, rather than blow up for a
    # minor reason when (say) a thousand readable directories are still
    # left to visit.  That logic is copied here.
    try:
        # Note that listdir and error are globals in this module due
        # to earlier import-*.
        names = listdir(top)
    except error, err:
        if onerror is not None:
            onerror(err)
        return

    dirs, nondirs = [], []
    for name in names:
        if isdir(join(top, name)):
            dirs.append(name)
        else:
            nondirs.append(name)

    if topdown:
        yield top, dirs, nondirs
    for name in dirs:
        path = join(top, name)
        if not islink(path):
            for x in walk(path, topdown, onerror):
                yield x
    if not topdown:
        yield top, dirs, nondirs

__all__.append("walk")

# Make sure os.environ exists, at least
try:
    environ
except NameError:
    environ = {}

def execl(file, *args):
    """execl(file, *args)

    Execute the executable file with argument list args, replacing the
    current process. """
    execv(file, args)

def execle(file, *args):
    """execle(file, *args, env)

    Execute the executable file with argument list args and
    environment env, replacing the current process. """
    env = args[-1]
    execve(file, args[:-1], env)

def execlp(file, *args):
    """execlp(file, *args)

    Execute the executable file (which is searched for along $PATH)
    with argument list args, replacing the current process. """
    execvp(file, args)

def execlpe(file, *args):
    """execlpe(file, *args, env)

    Execute the executable file (which is searched for along $PATH)
    with argument list args and environment env, replacing the current
    process. """
    env = args[-1]
    execvpe(file, args[:-1], env)

def execvp(file, args):
    """execp(file, args)

    Execute the executable file (which is searched for along $PATH)
    with argument list args, replacing the current process.
    args may be a list or tuple of strings. """
    _execvpe(file, args)

def execvpe(file, args, env):
    """execvpe(file, args, env)

    Execute the executable file (which is searched for along $PATH)
    with argument list args and environment env , replacing the
    current process.
    args may be a list or tuple of strings. """
    _execvpe(file, args, env)

__all__.extend(["execl","execle","execlp","execlpe","execvp","execvpe"])

def _execvpe(file, args, env=None):
    from errno import ENOENT, ENOTDIR

    if env is not None:
        func = execve
        argrest = (args, env)
    else:
        func = execv
        argrest = (args,)
        env = environ

    head, tail = path.split(file)
    if head:
        func(file, *argrest)
        return
    if 'PATH' in env:
        envpath = env['PATH']
    else:
        envpath = defpath
    PATH = envpath.split(pathsep)
    saved_exc = None
    saved_tb = None
    for dir in PATH:
        fullname = path.join(dir, file)
        try:
            func(fullname, *argrest)
        except error, e:
            tb = sys.exc_info()[2]
            if (e.errno != ENOENT and e.errno != ENOTDIR
                and saved_exc is None):
                saved_exc = e
                saved_tb = tb
    if saved_exc:
        raise error, saved_exc, saved_tb
    raise error, e, tb

# Change environ to automatically call putenv() if it exists
try:
    # This will fail if there's no putenv
    putenv
except NameError:
    pass
else:
    import UserDict

    # Fake unsetenv() for Windows
    # not sure about os2 here but
    # I'm guessing they are the same.

    if name in ('os2', 'nt'):
        def unsetenv(key):
            putenv(key, "")

    if name == "riscos":
        # On RISC OS, all env access goes through getenv and putenv
        from riscosenviron import _Environ
    elif name in ('os2', 'nt'):  # Where Env Var Names Must Be UPPERCASE
        # But we store them as upper case
        class _Environ(UserDict.IterableUserDict):
            def __init__(self, environ):
                UserDict.UserDict.__init__(self)
                data = self.data
                for k, v in environ.items():
                    data[k.upper()] = v
            def __setitem__(self, key, item):
                putenv(key, item)
                self.data[key.upper()] = item
            def __getitem__(self, key):
                return self.data[key.upper()]
            try:
                unsetenv
            except NameError:
                def __delitem__(self, key):
                    del self.data[key.upper()]
            else:
                def __delitem__(self, key):
                    unsetenv(key)
                    del self.data[key.upper()]
            def __contains__(self, key):
                return key.upper() in self.data
            def get(self, key, failobj=None):
                return self.data.get(key.upper(), failobj)
            def update(self, dict=None, **kwargs):
                if dict:
                    try:
                        keys = dict.keys()
                    except AttributeError:
                        # List of (key, value)
                        for k, v in dict:
                            self[k] = v
                    else:
                        # got keys
                        # cannot use items(), since mappings
                        # may not have them.
                        for k in keys:
                            self[k] = dict[k]
                if kwargs:
                    self.update(kwargs)
            def copy(self):
                return dict(self)

    else:  # Where Env Var Names Can Be Mixed Case
        class _Environ(UserDict.IterableUserDict):
            def __init__(self, environ):
                UserDict.UserDict.__init__(self)
                self.data = environ
            def __setitem__(self, key, item):
                putenv(key, item)
                self.data[key] = item
            def update(self,  dict=None, **kwargs):
                if dict:
                    try:
                        keys = dict.keys()
                    except AttributeError:
                        # List of (key, value)
                        for k, v in dict:
                            self[k] = v
                    else:
                        # got keys
                        # cannot use items(), since mappings
                        # may not have them.
                        for k in keys:
                            self[k] = dict[k]
                if kwargs:
                    self.update(kwargs)
            try:
                unsetenv
            except NameError:
                pass
            else:
                def __delitem__(self, key):
                    unsetenv(key)
                    del self.data[key]
            def copy(self):
                return dict(self)


    environ = _Environ(environ)

def getenv(key, default=None):
    """Get an environment variable, return None if it doesn't exist.
    The optional second argument can specify an alternate default."""
    return environ.get(key, default)
__all__.append("getenv")

def _exists(name):
    try:
        eval(name)
        return True
    except NameError:
        return False

# Supply spawn*() (probably only for Unix)
if _exists("fork") and not _exists("spawnv") and _exists("execv"):

    P_WAIT = 0
    P_NOWAIT = P_NOWAITO = 1

    # XXX Should we support P_DETACH?  I suppose it could fork()**2
    # and close the std I/O streams.  Also, P_OVERLAY is the same
    # as execv*()?

    def _spawnvef(mode, file, args, env, func):
        # Internal helper; func is the exec*() function to use
        pid = fork()
        if not pid:
            # Child
            try:
                if env is None:
                    func(file, args)
                else:
                    func(file, args, env)
            except:
                _exit(127)
        else:
            # Parent
            if mode == P_NOWAIT:
                return pid # Caller is responsible for waiting!
            while 1:
                wpid, sts = waitpid(pid, 0)
                if WIFSTOPPED(sts):
                    continue
                elif WIFSIGNALED(sts):
                    return -WTERMSIG(sts)
                elif WIFEXITED(sts):
                    return WEXITSTATUS(sts)
                else:
                    raise error, "Not stopped, signaled or exited???"

    def spawnv(mode, file, args):
        """spawnv(mode, file, args) -> integer

Execute file with arguments from args in a subprocess.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
        return _spawnvef(mode, file, args, None, execv)

    def spawnve(mode, file, args, env):
        """spawnve(mode, file, args, env) -> integer

Execute file with arguments from args in a subprocess with the
specified environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
        return _spawnvef(mode, file, args, env, execve)

    # Note: spawnvp[e] is't currently supported on Windows

    def spawnvp(mode, file, args):
        """spawnvp(mode, file, args) -> integer

Execute file (which is looked for along $PATH) with arguments from
args in a subprocess.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
        return _spawnvef(mode, file, args, None, execvp)

    def spawnvpe(mode, file, args, env):
        """spawnvpe(mode, file, args, env) -> integer

Execute file (which is looked for along $PATH) with arguments from
args in a subprocess with the supplied environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
        return _spawnvef(mode, file, args, env, execvpe)

if _exists("spawnv"):
    # These aren't supplied by the basic Windows code
    # but can be easily implemented in Python

    def spawnl(mode, file, *args):
        """spawnl(mode, file, *args) -> integer

Execute file with arguments from args in a subprocess.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
        return spawnv(mode, file, args)

    def spawnle(mode, file, *args):
        """spawnle(mode, file, *args, env) -> integer

Execute file with arguments from args in a subprocess with the
supplied environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
        env = args[-1]
        return spawnve(mode, file, args[:-1], env)


    __all__.extend(["spawnv", "spawnve", "spawnl", "spawnle",])


if _exists("spawnvp"):
    # At the moment, Windows doesn't implement spawnvp[e],
    # so it won't have spawnlp[e] either.
    def spawnlp(mode, file, *args):
        """spawnlp(mode, file, *args) -> integer

Execute file (which is looked for along $PATH) with arguments from
args in a subprocess with the supplied environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
        return spawnvp(mode, file, args)

    def spawnlpe(mode, file, *args):
        """spawnlpe(mode, file, *args, env) -> integer

Execute file (which is looked for along $PATH) with arguments from
args in a subprocess with the supplied environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
        env = args[-1]
        return spawnvpe(mode, file, args[:-1], env)


    __all__.extend(["spawnvp", "spawnvpe", "spawnlp", "spawnlpe",])


# Supply popen2 etc. (for Unix)
if _exists("fork"):
    if not _exists("popen2"):
        def popen2(cmd, mode="t", bufsize=-1):
            """Execute the shell command 'cmd' in a sub-process.  On UNIX, 'cmd'
            may be a sequence, in which case arguments will be passed directly to
            the program without shell intervention (as with os.spawnv()).  If 'cmd'
            is a string it will be passed to the shell (as with os.system()). If
            'bufsize' is specified, it sets the buffer size for the I/O pipes.  The
            file objects (child_stdin, child_stdout) are returned."""
            import popen2
            stdout, stdin = popen2.popen2(cmd, bufsize)
            return stdin, stdout
        __all__.append("popen2")

    if not _exists("popen3"):
        def popen3(cmd, mode="t", bufsize=-1):
            """Execute the shell command 'cmd' in a sub-process.  On UNIX, 'cmd'
            may be a sequence, in which case arguments will be passed directly to
            the program without shell intervention (as with os.spawnv()).  If 'cmd'
            is a string it will be passed to the shell (as with os.system()). If
            'bufsize' is specified, it sets the buffer size for the I/O pipes.  The
            file objects (child_stdin, child_stdout, child_stderr) are returned."""
            import popen2
            stdout, stdin, stderr = popen2.popen3(cmd, bufsize)
            return stdin, stdout, stderr
        __all__.append("popen3")

    if not _exists("popen4"):
        def popen4(cmd, mode="t", bufsize=-1):
            """Execute the shell command 'cmd' in a sub-process.  On UNIX, 'cmd'
            may be a sequence, in which case arguments will be passed directly to
            the program without shell intervention (as with os.spawnv()).  If 'cmd'
            is a string it will be passed to the shell (as with os.system()). If
            'bufsize' is specified, it sets the buffer size for the I/O pipes.  The
            file objects (child_stdin, child_stdout_stderr) are returned."""
            import popen2
            stdout, stdin = popen2.popen4(cmd, bufsize)
            return stdin, stdout
        __all__.append("popen4")

import copy_reg as _copy_reg

def _make_stat_result(tup, dict):
    return stat_result(tup, dict)

def _pickle_stat_result(sr):
    (type, args) = sr.__reduce__()
    return (_make_stat_result, args)

try:
    _copy_reg.pickle(stat_result, _pickle_stat_result, _make_stat_result)
except NameError: # stat_result may not exist
    pass

def _make_statvfs_result(tup, dict):
    return statvfs_result(tup, dict)

def _pickle_statvfs_result(sr):
    (type, args) = sr.__reduce__()
    return (_make_statvfs_result, args)

try:
    _copy_reg.pickle(statvfs_result, _pickle_statvfs_result,
                     _make_statvfs_result)
except NameError: # statvfs_result may not exist
    pass

if not _exists("urandom"):
    def urandom(n):
        """urandom(n) -> str

        Return a string of n random bytes suitable for cryptographic use.

        """
        try:
            _urandomfd = open("/dev/urandom", O_RDONLY)
        except (OSError, IOError):
            raise NotImplementedError("/dev/urandom (or equivalent) not found")
        bytes = ""
        while len(bytes) < n:
            bytes += read(_urandomfd, n - len(bytes))
        close(_urandomfd)
        return bytes