diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py index a8eae616205..b540fcbd4d7 100644 --- a/Lib/test/test_os.py +++ b/Lib/test/test_os.py @@ -3382,6 +3382,15 @@ class FDInheritanceTests(unittest.TestCase): self.addCleanup(os.close, fd2) self.assertEqual(os.get_inheritable(fd2), False) + @unittest.skipUnless(sys.platform == 'win32', 'win32-specific test') + def test_dup_nul(self): + # os.dup() was creating inheritable fds for character files. + fd1 = os.open('NUL', os.O_RDONLY) + self.addCleanup(os.close, fd1) + fd2 = os.dup(fd1) + self.addCleanup(os.close, fd2) + self.assertFalse(os.get_inheritable(fd2)) + @unittest.skipUnless(hasattr(os, 'dup2'), "need os.dup2()") def test_dup2(self): fd = os.open(__file__, os.O_RDONLY) diff --git a/Misc/NEWS.d/next/Windows/2019-06-13-04-15-51.bpo-37267.Ygo5ef.rst b/Misc/NEWS.d/next/Windows/2019-06-13-04-15-51.bpo-37267.Ygo5ef.rst new file mode 100644 index 00000000000..a4dcfcde35b --- /dev/null +++ b/Misc/NEWS.d/next/Windows/2019-06-13-04-15-51.bpo-37267.Ygo5ef.rst @@ -0,0 +1,2 @@ +On Windows, :func:`os.dup` no longer creates an inheritable fd when handling +a character file. diff --git a/Python/fileutils.c b/Python/fileutils.c index 178e2f1268f..93c093f89b4 100644 --- a/Python/fileutils.c +++ b/Python/fileutils.c @@ -1776,7 +1776,6 @@ _Py_dup(int fd) { #ifdef MS_WINDOWS HANDLE handle; - DWORD ftype; #endif assert(PyGILState_Check()); @@ -1790,9 +1789,6 @@ _Py_dup(int fd) return -1; } - /* get the file type, ignore the error if it failed */ - ftype = GetFileType(handle); - Py_BEGIN_ALLOW_THREADS _Py_BEGIN_SUPPRESS_IPH fd = dup(fd); @@ -1803,14 +1799,11 @@ _Py_dup(int fd) return -1; } - /* Character files like console cannot be make non-inheritable */ - if (ftype != FILE_TYPE_CHAR) { - if (_Py_set_inheritable(fd, 0, NULL) < 0) { - _Py_BEGIN_SUPPRESS_IPH - close(fd); - _Py_END_SUPPRESS_IPH - return -1; - } + if (_Py_set_inheritable(fd, 0, NULL) < 0) { + _Py_BEGIN_SUPPRESS_IPH + close(fd); + _Py_END_SUPPRESS_IPH + return -1; } #elif defined(HAVE_FCNTL_H) && defined(F_DUPFD_CLOEXEC) Py_BEGIN_ALLOW_THREADS