arch-image-builder/builder/build/mount.py

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import os
from logging import getLogger
from builder.lib.context import ArchBuilderContext
from builder.lib.mount import MountTab
log = getLogger(__name__)
def init_rootfs(ctx: ArchBuilderContext):
"""
Initialize Arch Linux rootfs
"""
path = ctx.get_rootfs()
def mkdir(mode, *names):
real = os.path.join(path, *names)
if not os.path.exists(real):
log.debug(f"create folder {real} with {mode:04o}")
os.makedirs(real, mode=mode)
log.debug(f"initializing rootfs folders at {path}")
mkdir(0o0755, path)
mkdir(0o0755, "dev")
mkdir(0o0555, "proc")
mkdir(0o0755, "run")
mkdir(0o0555, "sys")
mkdir(0o0755, "var", "lib", "pacman")
mkdir(0o0755, "etc", "pacman.d")
log.info(f"initialized rootfs folders at {path}")
def undo_mounts(ctx: ArchBuilderContext):
"""
Clean up mount points
"""
if len(ctx.mounted) <= 0: return
log.debug("undo mount points")
ctx.chroot = False
while len(ctx.mounted) > 0:
unmounted = 0
for mount in ctx.mounted.copy():
try:
mount.umount()
ctx.mounted.remove(mount)
unmounted += 1
except:
pass
if unmounted == 0:
raise RuntimeError("failed to umount all")
mnts = MountTab.parse_mounts()
if any(mnts.find_folder(ctx.work)):
raise RuntimeError("mount points not cleanup")
def init_mount(ctx: ArchBuilderContext):
"""
Setup mount points for rootfs
"""
root = ctx.get_rootfs()
def symlink(target, *names):
real = os.path.join(root, *names)
if not os.path.exists(real):
log.debug(f"create symlink {real} -> {target}")
os.symlink(target, real)
def root_mount(source, target, fstype, options):
real = os.path.realpath(os.path.join(root, target))
ctx.mount(source, real, fstype, options)
try:
# ensure mount point is clean
mnts = MountTab.parse_mounts()
if any(mnts.find_folder(ctx.work)):
raise RuntimeError("mount points not cleanup")
root_mount("proc", "proc", "proc", "nosuid,noexec,nodev")
root_mount("sys", "sys", "sysfs", "nosuid,noexec,nodev,ro")
root_mount("dev", "dev", "devtmpfs", "mode=0755,nosuid")
root_mount("pts", "dev/pts", "devpts", "mode=0620,gid=5,nosuid,noexec")
root_mount("shm", "dev/shm", "tmpfs", "mode=1777,nosuid,nodev")
root_mount("run", "run", "tmpfs", "nosuid,nodev,mode=0755")
root_mount("tmp", "tmp", "tmpfs", "mode=1777,strictatime,nodev,nosuid")
# symbolic links for some script tools (e.g. mkinitcpio)
symlink("/proc/self/fd", "dev", "fd")
symlink("/proc/self/fd/0", "dev", "stdin")
symlink("/proc/self/fd/1", "dev", "stdout")
symlink("/proc/self/fd/2", "dev", "stderr")
ctx.chroot = True
except:
log.error("failed to initialize mount points")
undo_mounts(ctx)
raise