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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"pathlib.Path.copy() hangs on FIFO pipes and loops infinitely on /dev/zero","articleBody":"# Bug Description\n`pathlib.Path.copy()` (introduced recently) attempts to open and copy any file type that is not a directory or a symlink. This causes severe issues with special files:\n1.  **FIFOs (Named Pipes)**: Opening a FIFO for reading blocks indefinitely if there is no writer, causing the process to hang using CPU.\n2.  **Infinite Sources**: Reading from character devices like `/dev/zero` results in an infinite loop, potentially filling up the disk or freezing the application.\n\n`shutil.copyfile` correctly handles this by raising `SpecialFileError` (or similar) when encountering these files. `pathlib` should behave similarly or at least safely.\n\n# Reproduction\n```python\nimport os\nimport pathlib\nimport signal\nimport time\n\nfifo_name = \"test_fifo_hang\"\nif os.path.exists(fifo_name):\n    os.remove(fifo_name)\nos.mkfifo(fifo_name)\n\n# This will hang indefinitely\nprint(\"Attempting to copy FIFO...\")\np = pathlib.Path(fifo_name)\ntry:\n    p.copy(\"test_fifo_dest\") \nexcept Exception as e:\n    print(f\"Caught: {e}\")\nelse:\n    print(\"Copy finished (unexpected!)\")\nfinally:\n    os.remove(fifo_name)\n```\n\n# Expected Behavior\nThe operation should fail immediately with `io.UnsupportedOperation` or `shutil.SameFileError` / `SpecialFileError` instead of hanging or looping.\n\n# Proposed Solution\nCheck `is_file()` in `pathlib.Path.copy` (specifically `_copy_from`) to ensure we only copy regular files.\n\nI have a PR ready for this.\n\n### CPython versions tested on:\n\n3.14\n\n### Operating systems tested on:\n\nmacOS\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-143966\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/tonghuaroot","@type":"Person","name":"tonghuaroot"},"datePublished":"2026-01-17T15:44:50.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/143968/cpython/issues/143968"}