Issue #12856: Ensure child processes do not inherit the parent's random seed for filename generation in the tempfile module.
Patch by Brian Harring.
diff --git a/Lib/test/test_tempfile.py b/Lib/test/test_tempfile.py
index f7f5bda..50cf3b4 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 @@
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)