https://github.com/python/cpython/commit/704bb69bd8d99c86359e174684b37a08a5d0c165 commit: 704bb69bd8d99c86359e174684b37a08a5d0c165 branch: 3.13 author: Miss Islington (bot) <[email protected]> committer: gpshead <[email protected]> date: 2025-11-29T06:49:56Z summary:
[3.13] GH-134453: Fix subprocess memoryview input handling on POSIX (GH-134949) (#142063) GH-134453: Fix subprocess memoryview input handling on POSIX (GH-134949) Fix inconsistent subprocess.Popen.communicate() behavior between Windows and POSIX when using memoryview objects with non-byte elements as input. On POSIX systems, the code was incorrectly comparing bytes written against element count instead of byte count, causing data truncation for large inputs with non-byte element types. Changes: - Cast memoryview inputs to byte view when input is already a memoryview - Fix progress tracking to use len(input_view) instead of len(self._input) - Add comprehensive test coverage for memoryview inputs 🤖 Generated with [Claude Code](https://claude.ai/code) * old-man-yells-at-ReST * Update 2025-05-30-18-37-44.gh-issue-134453.kxkA-o.rst * assertIsNone review feedback * fix memoryview_nonbytes test to fail without our fix on main, and have a nicer error. Thanks to Peter Bierma @ZeroIntensity for the code review. (cherry picked from commit cc6bc4c97f7be5b401a91119ba603e6c1a07c99b) Co-authored-by: Gregory P. Smith <[email protected]> files: A Misc/NEWS.d/next/Library/2025-05-30-18-37-44.gh-issue-134453.kxkA-o.rst M Lib/subprocess.py M Lib/test/test_subprocess.py diff --git a/Lib/subprocess.py b/Lib/subprocess.py index ffc3fdf6afb5c7..0f308489efc711 100644 --- a/Lib/subprocess.py +++ b/Lib/subprocess.py @@ -2105,7 +2105,10 @@ def _communicate(self, input, endtime, orig_timeout): self._save_input(input) if self._input: - input_view = memoryview(self._input) + if not isinstance(self._input, memoryview): + input_view = memoryview(self._input) + else: + input_view = self._input.cast("b") # byte input required with _PopenSelector() as selector: if self.stdin and input: @@ -2141,7 +2144,7 @@ def _communicate(self, input, endtime, orig_timeout): selector.unregister(key.fileobj) key.fileobj.close() else: - if self._input_offset >= len(self._input): + if self._input_offset >= len(input_view): selector.unregister(key.fileobj) key.fileobj.close() elif key.fileobj in (self.stdout, self.stderr): diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py index 8b2f48b0fc0119..d14c4546347c3b 100644 --- a/Lib/test/test_subprocess.py +++ b/Lib/test/test_subprocess.py @@ -956,6 +956,48 @@ def test_communicate(self): self.assertEqual(stdout, b"banana") self.assertEqual(stderr, b"pineapple") + def test_communicate_memoryview_input(self): + # Test memoryview input with byte elements + test_data = b"Hello, memoryview!" + mv = memoryview(test_data) + p = subprocess.Popen([sys.executable, "-c", + 'import sys; sys.stdout.write(sys.stdin.read())'], + stdin=subprocess.PIPE, + stdout=subprocess.PIPE) + self.addCleanup(p.stdout.close) + self.addCleanup(p.stdin.close) + (stdout, stderr) = p.communicate(mv) + self.assertEqual(stdout, test_data) + self.assertIsNone(stderr) + + def test_communicate_memoryview_input_nonbyte(self): + # Test memoryview input with non-byte elements (e.g., int32) + # This tests the fix for gh-134453 where non-byte memoryviews + # had incorrect length tracking on POSIX + import array + # Create an array of 32-bit integers that's large enough to trigger + # the chunked writing behavior (> PIPE_BUF) + pipe_buf = getattr(select, 'PIPE_BUF', 512) + # Each 'i' element is 4 bytes, so we need more than pipe_buf/4 elements + # Add some extra to ensure we exceed the buffer size + num_elements = pipe_buf + 1 + test_array = array.array('i', [0x64306f66 for _ in range(num_elements)]) + expected_bytes = test_array.tobytes() + mv = memoryview(test_array) + + p = subprocess.Popen([sys.executable, "-c", + 'import sys; ' + 'data = sys.stdin.buffer.read(); ' + 'sys.stdout.buffer.write(data)'], + stdin=subprocess.PIPE, + stdout=subprocess.PIPE) + self.addCleanup(p.stdout.close) + self.addCleanup(p.stdin.close) + (stdout, stderr) = p.communicate(mv) + self.assertEqual(stdout, expected_bytes, + msg=f"{len(stdout)=} =? {len(expected_bytes)=}") + self.assertIsNone(stderr) + def test_communicate_timeout(self): p = subprocess.Popen([sys.executable, "-c", 'import sys,os,time;' diff --git a/Misc/NEWS.d/next/Library/2025-05-30-18-37-44.gh-issue-134453.kxkA-o.rst b/Misc/NEWS.d/next/Library/2025-05-30-18-37-44.gh-issue-134453.kxkA-o.rst new file mode 100644 index 00000000000000..fee975ea70230c --- /dev/null +++ b/Misc/NEWS.d/next/Library/2025-05-30-18-37-44.gh-issue-134453.kxkA-o.rst @@ -0,0 +1,4 @@ +Fixed :func:`subprocess.Popen.communicate` ``input=`` handling of :class:`memoryview` +instances that were non-byte shaped on POSIX platforms. Those are now properly +cast to a byte shaped view instead of truncating the input. Windows platforms +did not have this bug. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
