127 lines
4.0 KiB
Python
127 lines
4.0 KiB
Python
from __future__ import annotations
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import subprocess
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import pathlib
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from pydantic import BaseModel
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from os.path import exists
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from selfprivacy_api.utils.block_devices import BlockDevice, BlockDevices
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# tests override it to a tmpdir
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VOLUMES_PATH = "/volumes"
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class BindError(Exception):
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pass
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class OwnedPath(BaseModel):
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"""
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A convenient interface for explicitly defining ownership of service folders.
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One overrides Service.get_owned_paths() for this.
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Why this exists?:
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One could use Bind to define ownership but then one would need to handle drive which
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is unnecessary and produces code duplication.
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It is also somewhat semantically wrong to include Owned Path into Bind
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instead of user and group. Because owner and group in Bind are applied to
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the original folder on the drive, not to the binding path. But maybe it is
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ok since they are technically both owned. Idk yet.
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"""
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path: str
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owner: str
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group: str
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class Bind:
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"""
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A directory that resides on some volume but we mount it into fs where we need it.
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Used for storing service data.
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"""
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def __init__(self, binding_path: str, owner: str, group: str, drive: BlockDevice):
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self.binding_path = binding_path
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self.owner = owner
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self.group = group
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self.drive = drive
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# TODO: delete owned path interface from Service
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@staticmethod
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def from_owned_path(path: OwnedPath, drive_name: str) -> Bind:
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drive = BlockDevices().get_block_device(drive_name)
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if drive is None:
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raise BindError(f"No such drive: {drive_name}")
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return Bind(
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binding_path=path.path, owner=path.owner, group=path.group, drive=drive
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)
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def bind_foldername(self) -> str:
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return self.binding_path.split("/")[-1]
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def location_at_volume(self) -> str:
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return f"{VOLUMES_PATH}/{self.drive.name}/{self.bind_foldername()}"
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def validate(self) -> None:
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path = pathlib.Path(self.location_at_volume())
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if not path.exists():
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raise BindError(f"directory {path} is not found.")
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if not path.is_dir():
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raise BindError(f"{path} is not a directory.")
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if path.owner() != self.owner:
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raise BindError(f"{path} is not owned by {self.owner}.")
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def bind(self) -> None:
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if not exists(self.binding_path):
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raise BindError(f"cannot bind to a non-existing path: {self.binding_path}")
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source = self.location_at_volume()
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target = self.binding_path
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try:
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subprocess.run(
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["mount", "--bind", source, target],
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stderr=subprocess.PIPE,
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check=True,
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)
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except subprocess.CalledProcessError as error:
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print(error.stderr)
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raise BindError(f"Unable to bind {source} to {target} :{error.stderr}")
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def unbind(self) -> None:
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if not exists(self.binding_path):
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raise BindError(f"cannot unbind a non-existing path: {self.binding_path}")
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try:
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subprocess.run(
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# umount -l ?
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["umount", self.binding_path],
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check=True,
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)
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except subprocess.CalledProcessError:
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raise BindError(f"Unable to unmount folder {self.binding_path}.")
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pass
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def ensure_ownership(self) -> None:
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true_location = self.location_at_volume()
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try:
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subprocess.run(
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[
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"chown",
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"-R",
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f"{self.owner}:{self.group}",
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# Could we just chown the binded location instead?
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true_location,
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],
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check=True,
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stderr=subprocess.PIPE,
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)
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except subprocess.CalledProcessError as error:
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print(error.stderr)
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error_message = (
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f"Unable to set ownership of {true_location} :{error.stderr}"
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)
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raise BindError(error_message)
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