117 lines
3.1 KiB
Python
117 lines
3.1 KiB
Python
from pathlib import Path
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import tempfile
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from typing import Optional
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from lmm.cmd import run_sudo_cmd
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def compute_workdirs_location(mount: Path) -> Path:
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with open("/proc/mounts", "r") as f:
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mounts = f.read().split("\n")
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mounted_dirs = [
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m for line in mounts if line != "" and (m := line.strip().split(" ")[1]) != "/"
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]
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mounted_dirs.sort()
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closest_mount = None
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for m in mounted_dirs:
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if str(mount).startswith(m) and len(m) > len(closest_mount or ""):
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closest_mount = m
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continue
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return Path("/tmp") if closest_mount is None else Path(closest_mount) / ".temp"
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class OverlayFSMount:
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upper: Optional[Path]
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lower: list[Path | str]
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workdir: Optional[tempfile.TemporaryDirectory]
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mount_path: Path
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_mounted: bool
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cd: Optional[Path]
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def __init__(
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self,
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upper: Optional[Path],
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lower: list[Path | str],
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mount: Path,
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cd: Optional[Path] = None,
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):
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self.upper = upper
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self.lower = lower
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self.mount_path = mount
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self._mounted = False
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self.cd = cd
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assert len(lower) < 500, "overlayfs only supports up-to 500 lower directories"
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def create_workdir(self) -> Path:
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# Ensure the temporary directory for workdirs exists
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workdir_location = compute_workdirs_location(self.mount_path)
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if not workdir_location.exists():
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workdir_location.mkdir(parents=True, exist_ok=True)
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# Create the workdir
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self.workdir = tempfile.TemporaryDirectory(
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dir=workdir_location,
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)
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print(f"Temporary workdir {self.workdir.name} created")
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return Path(self.workdir.name)
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def mount(self) -> Optional[Path]:
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lower = ":".join([str(l) for l in self.lower])
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options = f"lowerdir={lower}"
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if self.upper is not None:
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workdir = self.create_workdir()
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options += f",upperdir={self.upper},workdir={workdir}"
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result = run_sudo_cmd(
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[
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"mount",
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"-t",
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"overlay",
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"overlay",
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"-o",
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options,
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str(self.mount_path),
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],
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cd=self.cd,
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)
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print("Mount result:", result)
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if not result == 0:
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return None
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self._mounted = True
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return self.mount_path
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def unmount(self):
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if self._mounted:
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print("Unmounting...")
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# Remove the mount
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run_sudo_cmd(
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[
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"umount",
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str(self.mount_path),
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]
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)
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# Remove the temporary workdir
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if self.workdir is not None:
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try:
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# TODO: This fails because the workdir is owned by root
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self.workdir.cleanup()
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except PermissionError:
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print(f"Failed to clean temporary directory {self.workdir.name}")
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self._mounted = False
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def __del__(self):
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self.unmount()
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