GH-134453: Fix subprocess memoryview input handling on POSIX #134949
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gpshead
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needs backport to 3.13
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) Co-Authored-By: Claude <[email protected]> pre-commit-whitespace-fixup
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| self.addCleanup(p.stdin.close) | ||
| (stdout, stderr) = p.communicate(mv) | ||
| self.assertEqual(stdout, test_data) | ||
| self.assertEqual(stderr, None) |
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Use assertIsNone
Suggested change
| self.assertEqual(stderr, None) | |
| self.assertIsNone(stderr, None) |
| self.addCleanup(p.stdin.close) | ||
| (stdout, stderr) = p.communicate(mv) | ||
| self.assertEqual(stdout, expected_bytes) | ||
| self.assertEqual(stderr, None) |
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| self.assertEqual(stderr, None) | |
| self.assertIsNone(stderr, None) |
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| num_elements = (pipe_buf // 4) + 100 | ||
| test_array = array.array('i', range(num_elements)) # 'i' = signed int (4 bytes each) |
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Hmm, this test passes on the main branch. I think we want something like this:
Suggested change
| num_elements = (pipe_buf // 4) + 100 | |
| test_array = array.array('i', range(num_elements)) # 'i' = signed int (4 bytes each) | |
| num_elements = pipe_buf + 1 | |
| test_array = array.array('i', [1 for _ in range(num_elements)]) |
From what I can tell, the pipe is taking each integer as a single byte.
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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:
subprocess.Popen.communicate()behavior between Windows and Posix on non-byte memoryview input #134453