96 lines
2.7 KiB
Python
96 lines
2.7 KiB
Python
"""
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Device Handling for pipeline stages
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Specific type of artifacts require device support, such as
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loopback devices or device mapper. Since stages are always
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run in a container and are isolated from the host, they do
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not have direct access to devices and specifically can not
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setup new ones.
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Therefore device handling is done at the osbuild level with
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the help of a device host services. Device specific modules
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provide the actual functionality and thus the core device
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support in osbuild itself is abstract.
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"""
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import abc
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import hashlib
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import json
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from typing import Dict
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from osbuild import host
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class Device:
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"""
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A single device with its corresponding options
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"""
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def __init__(self, name, info, parent, options: Dict):
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self.name = name
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self.info = info
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self.parent = parent
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self.options = options or {}
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self.id = self.calc_id()
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def calc_id(self):
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# NB: Since the name of the device is arbitrary or prescribed
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# by the stage, it is not included in the id calculation.
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m = hashlib.sha256()
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m.update(json.dumps(self.info.name, sort_keys=True).encode())
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if self.parent:
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m.update(json.dumps(self.parent.id, sort_keys=True).encode())
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m.update(json.dumps(self.options, sort_keys=True).encode())
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return m.hexdigest()
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def open(self, mgr: host.ServiceManager, dev: str, parent: str, tree: str) -> Dict:
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args = {
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# global options
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"dev": dev,
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"tree": tree,
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"parent": parent,
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# per device options
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"options": self.options,
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}
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client = mgr.start(f"device/{self.name}", self.info.path)
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res = client.call("open", args)
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return res
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class DeviceService(host.Service):
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"""Device host service"""
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@abc.abstractmethod
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def open(self, devpath: str, parent: str, tree: str, options: Dict):
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"""Open a specific device
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This method must be implemented by the specific device service.
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It should open the device and create a device node in `devpath`.
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The return value must contain the relative path to the device
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node.
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"""
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@abc.abstractmethod
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def close(self):
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"""Close the device"""
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def stop(self):
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self.close()
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def dispatch(self, method: str, args, _fds):
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if method == "open":
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r = self.open(args["dev"],
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args["parent"],
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args["tree"],
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args["options"])
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return r, None
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if method == "close":
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r = self.close()
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return r, None
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raise host.ProtocolError("Unknown method")
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