test_subprocess.py 文件源码

def test_small_errpipe_write_fd(self):
        """Issue #15798: Popen should work when stdio fds are available."""
        new_stdin = os.dup(0)
        new_stdout = os.dup(1)
        try:
            os.close(0)
            os.close(1)

            # Side test: if errpipe_write fails to have its CLOEXEC
            # flag set this should cause the parent to think the exec
            # failed.  Extremely unlikely: everyone supports CLOEXEC.
            subprocess.Popen([
                    sys.executable, "-c",
                    "print('AssertionError:0:CLOEXEC failure.')"]).wait()
        finally:
            # Restore original stdin and stdout
            os.dup2(new_stdin, 0)
            os.dup2(new_stdout, 1)
            os.close(new_stdin)
            os.close(new_stdout)