58 lines
1.6 KiB
Python
58 lines
1.6 KiB
Python
"""userspace /dev device manager (udev) utilities"""
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import contextlib
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import pathlib
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# The default lock dir to use
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LOCKDIR = "/run/osbuild/locks/udev"
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class UdevInhibitor:
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"""
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Inhibit execution of certain udev rules for block devices
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This is the osbuild side of the custom mechanism that
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allows us to inhibit certain udev rules for block devices.
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For each device a lock file is created in a well known
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directory (LOCKDIR). A custom udev rule set[1] checks
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for the said lock file and inhibits other udev rules from
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being executed.
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See the aforementioned rules file for more information.
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[1] 10-osbuild-inhibitor.rules
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"""
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def __init__(self, path: pathlib.Path):
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self.path = path
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path.parent.mkdir(parents=True, exist_ok=True)
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def inhibit(self) -> None:
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self.path.touch()
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def release(self) -> None:
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with contextlib.suppress(FileNotFoundError):
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self.path.unlink()
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@property
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def active(self) -> bool:
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return self.path.exists()
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def __str__(self):
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return f"UdevInhibtor at '{self.path}'"
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@classmethod
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def for_dm_name(cls, name: str, lockdir=LOCKDIR):
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"""Inhibit a Device Mapper device with the given name"""
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path = pathlib.Path(lockdir, f"dm-{name}")
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ib = cls(path)
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ib.inhibit()
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return ib
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@classmethod
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def for_device(cls, major: int, minor: int, lockdir=LOCKDIR):
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"""Inhibit a device given its major and minor number"""
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path = pathlib.Path(lockdir, f"device-{major}:{minor}")
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ib = cls(path)
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ib.inhibit()
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return ib
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