Issue #12856: Ensure child processes do not inherit the parent's random seed for filename generation in the tempfile module.
Patch by Brian Harring.
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commit
c24847658f
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@ -108,8 +108,13 @@ class _RandomNameSequence:
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characters = "abcdefghijklmnopqrstuvwxyz0123456789_"
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def __init__(self):
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self.rng = _Random()
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@property
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def rng(self):
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cur_pid = _os.getpid()
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if cur_pid != getattr(self, '_rng_pid', None):
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self._rng = _Random()
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self._rng_pid = cur_pid
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return self._rng
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def __iter__(self):
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return self
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@ -1,6 +1,7 @@
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# tempfile.py unit tests.
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import tempfile
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import os
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import signal
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import sys
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import re
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import warnings
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@ -135,6 +136,37 @@ class test__RandomNameSequence(TC):
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except:
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self.failOnException("iteration")
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@unittest.skipUnless(hasattr(os, 'fork'),
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"os.fork is required for this test")
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def test_process_awareness(self):
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# ensure that the random source differs between
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# child and parent.
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read_fd, write_fd = os.pipe()
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pid = None
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try:
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pid = os.fork()
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if not pid:
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os.close(read_fd)
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os.write(write_fd, next(self.r).encode("ascii"))
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os.close(write_fd)
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# bypass the normal exit handlers- leave those to
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# the parent.
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os._exit(0)
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parent_value = next(self.r)
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child_value = os.read(read_fd, len(parent_value)).decode("ascii")
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finally:
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if pid:
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# best effort to ensure the process can't bleed out
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# via any bugs above
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try:
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os.kill(pid, signal.SIGKILL)
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except EnvironmentError:
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pass
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os.close(read_fd)
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os.close(write_fd)
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self.assertNotEqual(child_value, parent_value)
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test_classes.append(test__RandomNameSequence)
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@ -395,6 +395,10 @@ Core and Builtins
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Library
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-------
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- Issue #12856: Ensure child processes do not inherit the parent's random
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seed for filename generation in the tempfile module. Patch by Brian
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Harring.
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- Issue #9957: SpooledTemporaryFile.truncate() now accepts an optional size
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parameter, as other file-like objects. Patch by Ryan Kelly.
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