capture.py 文件源码

def safe_text_dupfile(f, mode, default_encoding="UTF8"):
    """ return a open text file object that's a duplicate of f on the
        FD-level if possible.
    """
    encoding = getattr(f, "encoding", None)
    try:
        fd = f.fileno()
    except Exception:
        if "b" not in getattr(f, "mode", "") and hasattr(f, "encoding"):
            # we seem to have a text stream, let's just use it
            return f
    else:
        newfd = os.dup(fd)
        if "b" not in mode:
            mode += "b"
        f = os.fdopen(newfd, mode, 0)  # no buffering
    return EncodedFile(f, encoding or default_encoding)