René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"CYGWIN doesn't support text mode in POSIX functions like MinGW.","articleBody":"# Bug report\n\n### Bug description:\n\nThis is one of the errors printed by `make test` on CYGWIN:\n```\nFAIL: test_textmode (test.test_tempfile.TestMkstempInner.test_textmode)\n----------------------------------------------------------------------\nTraceback (most recent call last):\n  File \"/home/carlo/packages/python/cpython/Lib/test/test_tempfile.py\", line 522, in test_textmode\n    self.assertEqual(os.read(f.fd, 20), b\"blat\")\n    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^\nAssertionError: b'blat\\x1aextra\\n' != b'blat'\n```\nFor explaining this issue, some information must be listed about the CTRL-Z (0x1A):\n\nOn CYGWIN:\n- Opening with `open()` in binary mode, it handles it as a clean flow of data without translations.\n- Opening with `open()` in text mode, it translates all 0xA to 0xD 0xA and the `read()` function ignores the CTRL-Z character as EOF.\n- Opening with `fopen()` in text mode, it also accepts the CTRL-Z as the EOF condition and this stops receiving data from `fread()`.\n\nOn native WIN32:\n- both `open()` and `fopen()` work in the same way if they open the file in text mode and CTRL-Z is treated as End-Of-File at both high and low levels, so `read()` and `fread()` give you the same results.\n\nSo, that's why this test is failing here.\n\nIn short, this kind of test cannot be executed on CYGWIN because `read()` never blocks on CTRL-Z by design.\nI would like to suggest to avoid it, if it happens.\nThe patch itself is simple, I  think that it is just need to write this before test_textmode:\n```\n@unittest.skipUnless(sys.platform != \"cygwin\" and has_textmode, \"text mode not available\")\n```\n\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nWindows\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-149947\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/carlo-bramini","@type":"Person","name":"carlo-bramini"},"datePublished":"2026-05-17T10:34:01.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/149946/cpython/issues/149946"}