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"""
Copyright (C) 2023 Michael Ablassmeier <abi@grinser.de>
Copyright (C) 2020 Red Hat, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
"""
from dataclasses import dataclass
@dataclass(frozen=True)
class SparseStreamTypes:
# pylint: disable=too-many-instance-attributes
"""Sparse stream format
Extended format based on the examples provided by the
ovirt-imageio project:
https://github.com/oVirt/ovirt-imageio/tree/master/examples
META: start of meta information header
DATA: data block marker
ZERO: zero block marker
STOP: stop block marker
TERM: termination identifier
FRAME: assembled frame
FRAME_LEN: length of frame
Stream format
=============
Stream is composed of one of more frames.
Meta frame
----------
Stream metadata, must be the first frame.
"meta" space start length "\r\n" <json-payload> \r\n
Metadata keys in the json payload:
- virtual-size: image virtual size in bytes
- data-size: number of bytes in data frames
- date: ISO 8601 date string
Data frame
----------
The header is followed by length bytes and terminator.
"data" space start length "\r\n" <length bytes> "\r\n"
Zero frame
----------
A zero extent, no payload.
"zero" space start length "\r\n"
Stop frame
----------
Marks the end of the stream, no payload.
"stop" space start length "\r\n"
Regular stream Example
-------
meta 0000000000000000 0000000000000083\r\n
{
[.]]
}\r\n
data 0000000000000000 00000000000100000\r\n
<1 MiB bytes>\r\n
zero 0000000000100000 00000000040000000\r\n
data 0000000040100000 00000000000001000\r\n
<4096 bytes>\r\n
stop 0000000000000000 00000000000000000\r\n
Compressed stream:
-------
Ends with compression marker:
stop 0000000000000000 00000000000000000\r\n
<json payload with compressed block sizes>\r\n
comp 0000000000000000 00000000000000010\r\n
"""
META: bytes = b"meta"
DATA: bytes = b"data"
COMP: bytes = b"comp"
ZERO: bytes = b"zero"
STOP: bytes = b"stop"
TERM: bytes = b"\r\n"
FRAME: bytes = b"%s %016x %016x" + TERM
FRAME_LEN: int = len(FRAME % (STOP, 0, 0))
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