diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py index deea207bfda..792794ca109 100644 --- a/Lib/test/test_os.py +++ b/Lib/test/test_os.py @@ -2221,6 +2221,26 @@ class TestInvalidFD(unittest.TestCase): def test_dup2(self): self.check(os.dup2, 20) + @unittest.skipUnless(hasattr(os, 'dup2'), 'test needs os.dup2()') + @unittest.skipIf( + support.is_emscripten, + "dup2() with negative fds is broken on Emscripten (see gh-102179)" + ) + def test_dup2_negative_fd(self): + valid_fd = os.open(__file__, os.O_RDONLY) + self.addCleanup(os.close, valid_fd) + fds = [ + valid_fd, + -1, + -2**31, + ] + for fd, fd2 in itertools.product(fds, repeat=2): + if fd != fd2: + with self.subTest(fd=fd, fd2=fd2): + with self.assertRaises(OSError) as ctx: + os.dup2(fd, fd2) + self.assertEqual(ctx.exception.errno, errno.EBADF) + @unittest.skipUnless(hasattr(os, 'fchmod'), 'test needs os.fchmod()') def test_fchmod(self): self.check(os.fchmod, 0) diff --git a/Misc/NEWS.d/next/Library/2023-02-23-15-06-01.gh-issue-102179.P6KQ4c.rst b/Misc/NEWS.d/next/Library/2023-02-23-15-06-01.gh-issue-102179.P6KQ4c.rst new file mode 100644 index 00000000000..f77493e267a --- /dev/null +++ b/Misc/NEWS.d/next/Library/2023-02-23-15-06-01.gh-issue-102179.P6KQ4c.rst @@ -0,0 +1 @@ +Fix :func:`os.dup2` error message for negative fds. diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c index 937233a3bd0..7beb2cee64a 100644 --- a/Modules/posixmodule.c +++ b/Modules/posixmodule.c @@ -9795,11 +9795,6 @@ os_dup2_impl(PyObject *module, int fd, int fd2, int inheritable) static int dup3_works = -1; #endif - if (fd < 0 || fd2 < 0) { - posix_error(); - return -1; - } - /* dup2() can fail with EINTR if the target FD is already open, because it * then has to be closed. See os_close_impl() for why we don't handle EINTR * upon close(), and therefore below.