https://github.com/python/cpython/commit/923056b2d41c4c28ad9163901053cd3824d775c5
commit: 923056b2d41c4c28ad9163901053cd3824d775c5
branch: main
author: Gregory P. Smith <[email protected]>
committer: gpshead <[email protected]>
date: 2025-11-29T05:03:06Z
summary:
gh-74389: gh-70560: subprocess.Popen.communicate() now ignores stdin.flush
error when closed (GH-142061)
gh-70560: gh-74389: subprocess.Popen.communicate() now ignores stdin.flush
error when closed
with a unittest and news entry.
files:
A Misc/NEWS.d/next/Library/2025-11-29-04-20-44.gh-issue-74389.pW3URj.rst
M Lib/subprocess.py
M Lib/test/test_subprocess.py
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 168703828fc50e..99e2d0755d7e46 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -2077,6 +2077,10 @@ def _communicate(self, input, endtime, orig_timeout):
self.stdin.flush()
except BrokenPipeError:
pass # communicate() must ignore BrokenPipeError.
+ except ValueError:
+ # ignore ValueError: I/O operation on closed file.
+ if not self.stdin.closed:
+ raise
if not input:
try:
self.stdin.close()
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 5e73810dcb7253..2d717f985a3ac3 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1104,6 +1104,19 @@ def test_writes_before_communicate(self):
self.assertEqual(stdout, b"bananasplit")
self.assertEqual(stderr, b"")
+ def test_communicate_stdin_closed_before_call(self):
+ # gh-70560, gh-74389: stdin.close() before communicate()
+ # should not raise ValueError from stdin.flush()
+ with subprocess.Popen([sys.executable, "-c",
+ 'import sys; sys.exit(0)'],
+ stdin=subprocess.PIPE,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE) as p:
+ p.stdin.close() # Close stdin before communicate
+ # This should not raise ValueError
+ (stdout, stderr) = p.communicate()
+ self.assertEqual(p.returncode, 0)
+
def test_universal_newlines_and_text(self):
args = [
sys.executable, "-c",
diff --git
a/Misc/NEWS.d/next/Library/2025-11-29-04-20-44.gh-issue-74389.pW3URj.rst
b/Misc/NEWS.d/next/Library/2025-11-29-04-20-44.gh-issue-74389.pW3URj.rst
new file mode 100644
index 00000000000000..a9bf5f80d80c9f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-11-29-04-20-44.gh-issue-74389.pW3URj.rst
@@ -0,0 +1,3 @@
+When the stdin being used by a :class:`subprocess.Popen` instance is closed,
+this is now ignored in :meth:`subprocess.Popen.communicate` instead of
+leaving the class in an inconsistent state.
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