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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Iterating over ctypes pointer causes hang or segmentation fault","articleBody":"Trying to create iterable (`list`, `tuple`, `set` etc.) from `PyCPointer` instance leads to hang or segmentation fault.\r\nThis code causes hang and memory leak which goes until oom-killer kills python process:\r\n```\r\nimport ctypes\r\nx = ctypes.c_int32(12345)\r\nbuf4_p_t = ctypes.POINTER(ctypes.ARRAY(ctypes.c_byte, 4))\r\nbuf_p = ctypes.cast(ctypes.byref(x), buf4_p_t)\r\nlist(buf_p)\r\n```\r\nSimilar code that causes segmentation fault:\r\n```\r\nimport ctypes\r\nx = ctypes.c_int32(54321)\r\nxp = ctypes.pointer(x)\r\nlist(xp)\r\n```\r\nIterating over pointer using `for` statement leads to an infinite loop:\r\n`for i in buf_p: print(i)`\r\n`for i in xp: print(i)`\r\n`list(for i in buf_p)`\r\n\r\nTried on 3.10.3 and 3.11.0a6+, fails at both. \r\n\r\nThe possible reason is that `PyCPointer_Type` defines `sq_item` without defining `tp_iter`. \r\nDespite I can't imagine any reason why anyone might need to use pointer as iterable/sequence, raising `TypeError` in such situation would be a better option.\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-126318\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/chgnrdv","@type":"Person","name":"chgnrdv"},"datePublished":"2022-05-05T19:34:50.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/92347/cpython/issues/92347"}