This file is indexed.

/usr/lib/python2.7/dist-packages/gevent/os.py is in python-gevent 1.2.2-2.

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
"""
Low-level operating system functions from :mod:`os`.

Cooperative I/O
===============

This module provides cooperative versions of :func:`os.read` and
:func:`os.write`. These functions are *not* monkey-patched; you
must explicitly call them or monkey patch them yourself.

POSIX functions
---------------

On POSIX, non-blocking IO is available.

- :func:`nb_read`
- :func:`nb_write`
- :func:`make_nonblocking`

All Platforms
-------------

On non-POSIX platforms (e.g., Windows), non-blocking IO is not
available. On those platforms (and on POSIX), cooperative IO can
be done with the threadpool.

- :func:`tp_read`
- :func:`tp_write`

Child Processes
===============

The functions :func:`fork` and (on POSIX) :func:`forkpty` and :func:`waitpid` can be used
to manage child processes.

.. warning::

   Forking a process that uses greenlets does not eliminate all non-running
   greenlets. Any that were scheduled in the hub of the forking thread in the parent
   remain scheduled in the child; compare this to how normal threads operate. (This behaviour
   may change is a subsequent major release.)
"""

from __future__ import absolute_import

import os
import sys
from gevent.hub import get_hub, reinit
from gevent._compat import PY3
from gevent._util import copy_globals
import errno

EAGAIN = getattr(errno, 'EAGAIN', 11)

try:
    import fcntl
except ImportError:
    fcntl = None

__implements__ = ['fork']
__extensions__ = ['tp_read', 'tp_write']

_read = os.read
_write = os.write


ignored_errors = [EAGAIN, errno.EINTR]


if fcntl:

    __extensions__ += ['make_nonblocking', 'nb_read', 'nb_write']

    def make_nonblocking(fd):
        """Put the file descriptor *fd* into non-blocking mode if possible.

        :return: A boolean value that evaluates to True if successful."""
        flags = fcntl.fcntl(fd, fcntl.F_GETFL, 0)
        if not bool(flags & os.O_NONBLOCK):
            fcntl.fcntl(fd, fcntl.F_SETFL, flags | os.O_NONBLOCK)
            return True

    def nb_read(fd, n):
        """Read up to `n` bytes from file descriptor `fd`. Return a string
        containing the bytes read. If end-of-file is reached, an empty string
        is returned.

        The descriptor must be in non-blocking mode.
        """
        hub, event = None, None
        while True:
            try:
                return _read(fd, n)
            except OSError as e:
                if e.errno not in ignored_errors:
                    raise
                if not PY3:
                    sys.exc_clear()
            if hub is None:
                hub = get_hub()
                event = hub.loop.io(fd, 1)
            hub.wait(event)

    def nb_write(fd, buf):
        """Write bytes from buffer `buf` to file descriptor `fd`. Return the
        number of bytes written.

        The file descriptor must be in non-blocking mode.
        """
        hub, event = None, None
        while True:
            try:
                return _write(fd, buf)
            except OSError as e:
                if e.errno not in ignored_errors:
                    raise
                if not PY3:
                    sys.exc_clear()
            if hub is None:
                hub = get_hub()
                event = hub.loop.io(fd, 2)
            hub.wait(event)


def tp_read(fd, n):
    """Read up to *n* bytes from file descriptor *fd*. Return a string
    containing the bytes read. If end-of-file is reached, an empty string
    is returned.

    Reading is done using the threadpool.
    """
    return get_hub().threadpool.apply(_read, (fd, n))


def tp_write(fd, buf):
    """Write bytes from buffer *buf* to file descriptor *fd*. Return the
    number of bytes written.

    Writing is done using the threadpool.
    """
    return get_hub().threadpool.apply(_write, (fd, buf))


if hasattr(os, 'fork'):
    # pylint:disable=function-redefined,redefined-outer-name

    _raw_fork = os.fork

    def fork_gevent():
        """
        Forks the process using :func:`os.fork` and prepares the
        child process to continue using gevent before returning.

        .. note::

            The PID returned by this function may not be waitable with
            either the original :func:`os.waitpid` or this module's
            :func:`waitpid` and it may not generate SIGCHLD signals if
            libev child watchers are or ever have been in use. For
            example, the :mod:`gevent.subprocess` module uses libev
            child watchers (which parts of gevent use libev child
            watchers is subject to change at any time). Most
            applications should use :func:`fork_and_watch`, which is
            monkey-patched as the default replacement for
            :func:`os.fork` and implements the ``fork`` function of
            this module by default, unless the environment variable
            ``GEVENT_NOWAITPID`` is defined before this module is
            imported.

        .. versionadded:: 1.1b2
        """
        result = _raw_fork()
        if not result:
            reinit()
        return result

    def fork():
        """
        A wrapper for :func:`fork_gevent` for non-POSIX platforms.
        """
        return fork_gevent()

    if hasattr(os, 'forkpty'):
        _raw_forkpty = os.forkpty

        def forkpty_gevent():
            """
            Forks the process using :func:`os.forkpty` and prepares the
            child process to continue using gevent before returning.

            Returns a tuple (pid, master_fd). The `master_fd` is *not* put into
            non-blocking mode.

            Availability: Some Unix systems.

            .. seealso:: This function has the same limitations as :func:`fork_gevent`.

            .. versionadded:: 1.1b5
            """
            pid, master_fd = _raw_forkpty()
            if not pid:
                reinit()
            return pid, master_fd

        forkpty = forkpty_gevent

        __implements__.append('forkpty')
        __extensions__.append("forkpty_gevent")

    if hasattr(os, 'WNOWAIT') or hasattr(os, 'WNOHANG'):
        # We can only do this on POSIX
        import time

        _waitpid = os.waitpid
        _WNOHANG = os.WNOHANG

        # replaced by the signal module.
        _on_child_hook = lambda: None

        # {pid -> watcher or tuple(pid, rstatus, timestamp)}
        _watched_children = {}

        def _on_child(watcher, callback):
            # XXX: Could handle tracing here by not stopping
            # until the pid is terminated
            watcher.stop()
            _watched_children[watcher.pid] = (watcher.pid, watcher.rstatus, time.time())
            if callback:
                callback(watcher)
            # dispatch an "event"; used by gevent.signal.signal
            _on_child_hook()
            # now is as good a time as any to reap children
            _reap_children()

        def _reap_children(timeout=60):
            # Remove all the dead children that haven't been waited on
            # for the *timeout* seconds.
            # Some platforms queue delivery of SIGCHLD for all children that die;
            # in that case, a well-behaved application should call waitpid() for each
            # signal.
            # Some platforms (linux) only guarantee one delivery if multiple children
            # die. On that platform, the well-behave application calls waitpid() in a loop
            # until it gets back -1, indicating no more dead children need to be waited for.
            # In either case, waitpid should be called the same number of times as dead children,
            # thus removing all the watchers when a SIGCHLD arrives. The (generous) timeout
            # is to work with applications that neglect to call waitpid and prevent "unlimited"
            # growth.
            # Note that we don't watch for the case of pid wraparound. That is, we fork a new
            # child with the same pid as an existing watcher, but the child is already dead,
            # just not waited on yet.
            now = time.time()
            oldest_allowed = now - timeout
            dead = [pid for pid, val
                    in _watched_children.items()
                    if isinstance(val, tuple) and val[2] < oldest_allowed]
            for pid in dead:
                del _watched_children[pid]

        def waitpid(pid, options):
            """
            Wait for a child process to finish.

            If the child process was spawned using
            :func:`fork_and_watch`, then this function behaves
            cooperatively. If not, it *may* have race conditions; see
            :func:`fork_gevent` for more information.

            The arguments are as for the underlying
            :func:`os.waitpid`. Some combinations of *options* may not
            be supported cooperatively (as of 1.1 that includes
            WUNTRACED). Using a *pid* of 0 to request waiting on only processes
            from the current process group is not cooperative.

            Availability: POSIX.

            .. versionadded:: 1.1b1
            .. versionchanged:: 1.2a1
               More cases are handled in a cooperative manner.
            """
            # XXX Does not handle tracing children

            # So long as libev's loop doesn't run, it's OK to add
            # child watchers. The SIGCHLD handler only feeds events
            # for the next iteration of the loop to handle. (And the
            # signal handler itself is only called from the next loop
            # iteration.)

            if pid <= 0:
                # magic functions for multiple children.
                if pid == -1:
                    # Any child. If we have one that we're watching and that finished,
                    # we will use that one. Otherwise, let the OS take care of it.
                    for k, v in _watched_children.items():
                        if isinstance(v, tuple):
                            pid = k
                            break
                if pid <= 0:
                    # We didn't have one that was ready. If there are
                    # no funky options set, and the pid was -1
                    # (meaning any process, not 0, which means process
                    # group--- libev doesn't know about process
                    # groups) then we can use a child watcher of pid 0; otherwise,
                    # pass through to the OS.
                    if pid == -1 and options == 0:
                        hub = get_hub()
                        watcher = hub.loop.child(0, False)
                        hub.wait(watcher)
                        return watcher.rpid, watcher.rstatus
                    # There were funky options/pid, so we must go to the OS.
                    return _waitpid(pid, options)

            if pid in _watched_children:
                # yes, we're watching it
                if options & _WNOHANG or isinstance(_watched_children[pid], tuple):
                    # We're either asked not to block, or it already finished, in which
                    # case blocking doesn't matter
                    result = _watched_children[pid]
                    if isinstance(result, tuple):
                        # it finished. libev child watchers
                        # are one-shot
                        del _watched_children[pid]
                        return result[:2]
                    # it's not finished
                    return (0, 0)
                else:
                    # Ok, we need to "block". Do so via a watcher so that we're
                    # cooperative. We know it's our child, etc, so this should work.
                    watcher = _watched_children[pid]
                    # We can't start a watcher that's already started,
                    # so we can't reuse the existing watcher.
                    new_watcher = watcher.loop.child(pid, False)
                    get_hub().wait(new_watcher)
                    # Ok, so now the new watcher is done. That means
                    # the old watcher's callback (_on_child) should
                    # have fired, potentially taking this child out of
                    # _watched_children (but that could depend on how
                    # many callbacks there were to run, so use the
                    # watcher object directly; libev sets all the
                    # watchers at the same time).
                    return watcher.rpid, watcher.rstatus

            # we're not watching it and it may not even  be our child,
            # so we must go to the OS to be sure to get the right semantics (exception)
            return _waitpid(pid, options)

        def fork_and_watch(callback=None, loop=None, ref=False, fork=fork_gevent):
            """
            Fork a child process and start a child watcher for it in the parent process.

            This call cooperates with :func:`waitpid` to enable cooperatively waiting
            for children to finish. When monkey-patching, these functions are patched in as
            :func:`os.fork` and :func:`os.waitpid`, respectively.

            In the child process, this function calls :func:`gevent.hub.reinit` before returning.

            Availability: POSIX.

            :keyword callback: If given, a callable that will be called with the child watcher
                when the child finishes.
            :keyword loop: The loop to start the watcher in. Defaults to the
                loop of the current hub.
            :keyword fork: The fork function. Defaults to :func:`the one defined in this
                module <gevent.os.fork_gevent>` (which automatically calls :func:`gevent.hub.reinit`).
                Pass the builtin :func:`os.fork` function if you do not need to
                initialize gevent in the child process.

            .. versionadded:: 1.1b1
            .. seealso::
                :func:`gevent.monkey.get_original` To access the builtin :func:`os.fork`.
            """
            pid = fork()
            if pid:
                # parent
                loop = loop or get_hub().loop
                watcher = loop.child(pid, ref=ref)
                _watched_children[pid] = watcher
                watcher.start(_on_child, watcher, callback)
            return pid

        __extensions__.append('fork_and_watch')
        __extensions__.append('fork_gevent')

        if 'forkpty' in __implements__:
            def forkpty_and_watch(callback=None, loop=None, ref=False, forkpty=forkpty_gevent):
                """
                Like :func:`fork_and_watch`, except using :func:`forkpty_gevent`.

                Availability: Some Unix systems.

                .. versionadded:: 1.1b5
                """
                result = []

                def _fork():
                    pid_and_fd = forkpty()
                    result.append(pid_and_fd)
                    return pid_and_fd[0]
                fork_and_watch(callback, loop, ref, _fork)
                return result[0]

            __extensions__.append('forkpty_and_watch')

        # Watch children by default
        if not os.getenv('GEVENT_NOWAITPID'):
            # Broken out into separate functions instead of simple name aliases
            # for documentation purposes.
            def fork(*args, **kwargs):
                """
                Forks a child process and starts a child watcher for it in the
                parent process so that ``waitpid`` and SIGCHLD work as expected.

                This implementation of ``fork`` is a wrapper for :func:`fork_and_watch`
                when the environment variable ``GEVENT_NOWAITPID`` is *not* defined.
                This is the default and should be used by most applications.

                .. versionchanged:: 1.1b2
                """
                # take any args to match fork_and_watch
                return fork_and_watch(*args, **kwargs)

            if 'forkpty' in __implements__:
                def forkpty(*args, **kwargs):
                    """
                    Like :func:`fork`, but using :func:`forkpty_gevent`.

                    This implementation of ``forkpty`` is a wrapper for :func:`forkpty_and_watch`
                    when the environment variable ``GEVENT_NOWAITPID`` is *not* defined.
                    This is the default and should be used by most applications.

                    .. versionadded:: 1.1b5
                    """
                    # take any args to match fork_and_watch
                    return forkpty_and_watch(*args, **kwargs)
            __implements__.append("waitpid")
        else:
            def fork():
                """
                Forks a child process, initializes gevent in the child,
                but *does not* prepare the parent to wait for the child or receive SIGCHLD.

                This implementation of ``fork`` is a wrapper for :func:`fork_gevent`
                when the environment variable ``GEVENT_NOWAITPID`` *is* defined.
                This is not recommended for most applications.
                """
                return fork_gevent()

            if 'forkpty' in __implements__:
                def forkpty():
                    """
                    Like :func:`fork`, but using :func:`os.forkpty`

                    This implementation of ``forkpty`` is a wrapper for :func:`forkpty_gevent`
                    when the environment variable ``GEVENT_NOWAITPID`` *is* defined.
                    This is not recommended for most applications.

                    .. versionadded:: 1.1b5
                    """
                    return forkpty_gevent()
            __extensions__.append("waitpid")

else:
    __implements__.remove('fork')

__imports__ = copy_globals(os, globals(),
                           names_to_ignore=__implements__ + __extensions__,
                           dunder_names_to_keep=())

__all__ = list(set(__implements__ + __extensions__))