util.py 文件源码

def duplicate(src, dst):
    """Alternative to shutil.copyfile, this will use os.link when possible.

    See shutil.copyfile for documention. Only `src` and `dst` are supported.
    Unlike copyfile, this will not overwrite the destination if it exists.

    """
    if os.path.isdir(src):
        # os.link will give a permission error
        raise OSError(errno.EISDIR, "Is a directory", src)
    if os.path.isdir(dst):
        # os.link will give a FileExists error
        raise OSError(errno.EISDIR, "Is a directory", dst)

    if os.path.exists(dst):
        # shutil.copyfile will overwrite the existing file
        raise OSError(errno.EEXIST, "File exists", src, "File exists", dst)

    try:
        os.link(src, dst)
    except OSError as e:
        if e.errno == errno.EXDEV:  # Invalid cross-device link
            shutil.copyfile(src, dst)
        else:
            raise