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pmbootstrap/pmb/helpers/mount.py
2024-10-30 12:39:45 +01:00

119 lines
3.8 KiB
Python

# Copyright 2023 Oliver Smith
# SPDX-License-Identifier: GPL-3.0-or-later
import os
from pathlib import Path, PurePath
import pmb.helpers
from pmb.core import Chroot
from pmb.types import PathString
import pmb.helpers.run
def ismount(folder: Path) -> bool:
"""Ismount() implementation that works for mount --bind.
Workaround for: https://bugs.python.org/issue29707
"""
folder = folder.resolve()
with open("/proc/mounts") as handle:
for line in handle:
words = line.split()
if len(words) >= 2 and Path(words[1]) == folder:
return True
if words[0] == folder:
return True
return False
def bind(
source: PathString, destination: Path, create_folders: bool = True, umount: bool = False
) -> None:
"""Mount --bind a folder and create necessary directory structure.
:param umount: when destination is already a mount point, umount it first.
"""
# Check/umount destination
if ismount(destination):
if umount:
umount_all(destination)
else:
return
# Check/create folders
for path in [source, destination]:
if os.path.exists(path):
continue
if create_folders:
pmb.helpers.run.root(["mkdir", "-p", path])
else:
raise RuntimeError(f"Mount failed, folder does not exist: {path}")
# Actually mount the folder
pmb.helpers.run.root(["mount", "--bind", source, destination])
# Verify that it has worked
if not ismount(destination):
raise RuntimeError(f"Mount failed: {source} -> {destination}")
def bind_file(source: Path, destination: Path, create_folders: bool = False) -> None:
"""Mount a file with the --bind option, and create the destination file, if necessary."""
# Skip existing mountpoint
if ismount(destination):
return
# Create empty file
if not destination.exists():
if create_folders:
dest_dir: Path = destination.parent
if not dest_dir.is_dir():
pmb.helpers.run.root(["mkdir", "-p", dest_dir])
pmb.helpers.run.root(["touch", destination])
# Mount
pmb.helpers.run.root(["mount", "--bind", source, destination])
def umount_all_list(prefix: Path, source: Path = Path("/proc/mounts")) -> list[Path]:
"""Parse `/proc/mounts` for all folders beginning with a prefix.
:source: can be changed for testcases
:returns: a list of folders that need to be umounted
"""
ret = []
prefix = prefix.resolve()
with source.open() as handle:
for line in handle:
words = line.split()
if len(words) < 2:
raise RuntimeError(f"Failed to parse line in {source}: {line}")
mountpoint = Path(words[1].replace(r"\040(deleted)", ""))
if mountpoint.is_relative_to(prefix): # is subpath
ret.append(mountpoint)
ret.sort(reverse=True)
return ret
def umount_all(folder: Path) -> None:
"""Umount all folders that are mounted inside a given folder."""
for mountpoint in umount_all_list(folder):
pmb.helpers.run.root(["umount", mountpoint])
if ismount(mountpoint):
raise RuntimeError(f"Failed to umount: {mountpoint}")
def mount_device_rootfs(chroot_rootfs: Chroot, chroot_base: Chroot = Chroot.native()) -> PurePath:
"""
Mount the device rootfs.
:param chroot_rootfs: the chroot where the rootfs that will be
installed on the device has been created (e.g.
"rootfs_qemu-amd64")
:param chroot_base: the chroot rootfs mounted to
:returns: the mountpoint (relative to the chroot)
"""
mountpoint = PurePath("/mnt", str(chroot_rootfs))
pmb.helpers.mount.bind(chroot_rootfs.path, chroot_base / mountpoint)
return mountpoint