diff options
| -rw-r--r-- | Lib/tempfile.py | 9 | ||||
| -rw-r--r-- | Lib/test/test_tempfile.py | 32 | ||||
| -rw-r--r-- | Misc/NEWS | 4 |
3 files changed, 43 insertions, 2 deletions
diff --git a/Lib/tempfile.py b/Lib/tempfile.py index e3afa3b0ac..39ebf5a943 100644 --- a/Lib/tempfile.py +++ b/Lib/tempfile.py @@ -108,8 +108,13 @@ class _RandomNameSequence: characters = "abcdefghijklmnopqrstuvwxyz0123456789_" - def __init__(self): - self.rng = _Random() + @property + def rng(self): + cur_pid = _os.getpid() + if cur_pid != getattr(self, '_rng_pid', None): + self._rng = _Random() + self._rng_pid = cur_pid + return self._rng def __iter__(self): return self diff --git a/Lib/test/test_tempfile.py b/Lib/test/test_tempfile.py index 5b0bca797e..8fe298607e 100644 --- a/Lib/test/test_tempfile.py +++ b/Lib/test/test_tempfile.py @@ -1,6 +1,7 @@ # tempfile.py unit tests. import tempfile import os +import signal import sys import re import warnings @@ -135,6 +136,37 @@ class test__RandomNameSequence(TC): except: self.failOnException("iteration") + @unittest.skipUnless(hasattr(os, 'fork'), + "os.fork is required for this test") + def test_process_awareness(self): + # ensure that the random source differs between + # child and parent. + read_fd, write_fd = os.pipe() + pid = None + try: + pid = os.fork() + if not pid: + os.close(read_fd) + os.write(write_fd, next(self.r).encode("ascii")) + os.close(write_fd) + # bypass the normal exit handlers- leave those to + # the parent. + os._exit(0) + parent_value = next(self.r) + child_value = os.read(read_fd, len(parent_value)).decode("ascii") + finally: + if pid: + # best effort to ensure the process can't bleed out + # via any bugs above + try: + os.kill(pid, signal.SIGKILL) + except EnvironmentError: + pass + os.close(read_fd) + os.close(write_fd) + self.assertNotEqual(child_value, parent_value) + + test_classes.append(test__RandomNameSequence) @@ -395,6 +395,10 @@ Core and Builtins Library ------- +- Issue #12856: Ensure child processes do not inherit the parent's random + seed for filename generation in the tempfile module. Patch by Brian + Harring. + - Issue #9957: SpooledTemporaryFile.truncate() now accepts an optional size parameter, as other file-like objects. Patch by Ryan Kelly. |