image_client.py 文件源码

def _get_file_size(self, obj):
        """Analyze file-like object and attempt to determine its size.

        :param obj: file-like object, typically redirected from stdin.
        :retval The file's size or None if it cannot be determined.
        """
        # For large images, we need to supply the size of the
        # image file. See LP Bugs #827660 and #845788.
        if hasattr(obj, 'seek') and hasattr(obj, 'tell'):
            try:
                obj.seek(0, os.SEEK_END)
                obj_size = obj.tell()
                obj.seek(0)
                return obj_size
            except IOError as e:
                if e.errno == errno.ESPIPE:
                    # Illegal seek. This means the user is trying
                    # to pipe image data to the client, e.g.
                    # echo testdata | bin/glance add blah..., or
                    # that stdin is empty, or that a file-like
                    # object which doesn't support 'seek/tell' has
                    # been supplied.
                    return None
                else:
                    raise
        else:
            # Cannot determine size of input image
            return None