debian-forge/osbuild/util/mnt.py
Gianluca Zuccarelli 9258bda89d util/mnt: add a remount paramater
This is just a temporary workaround to get the containers-storage
input working in `bootc-image-builder`
2024-03-11 18:15:24 +02:00

105 lines
3 KiB
Python

"""Mount utilities
"""
import contextlib
import enum
import subprocess
from typing import Optional
class MountPermissions(enum.Enum):
READ_WRITE = "rw"
READ_ONLY = "ro"
def mount(source, target, bind=True, ro=True, private=True, mode="0755"):
options = []
if ro:
options += [MountPermissions.READ_ONLY.value]
if mode:
options += [mode]
args = []
if bind:
args += ["--rbind"]
if private:
args += ["--make-rprivate"]
if options:
args += ["-o", ",".join(options)]
r = subprocess.run(["mount"] + args + [source, target],
stderr=subprocess.STDOUT,
stdout=subprocess.PIPE,
encoding="utf-8",
check=False)
if r.returncode != 0:
code = r.returncode
msg = r.stdout.strip()
raise RuntimeError(f"{msg} (code: {code})")
def umount(target, lazy=False):
args = []
if lazy:
args += ["--lazy"]
subprocess.run(["sync", "-f", target], check=True)
subprocess.run(["umount", "-R"] + args + [target], check=True)
class MountGuard(contextlib.AbstractContextManager):
def __init__(self):
self.mounts = []
self.remount = False
def mount(
self,
source,
target,
bind=True,
remount=False,
permissions: Optional[MountPermissions] = None,
mode="0755"):
self.remount = remount
options = []
if bind:
options += ["bind"]
if remount:
options += ["remount"]
if permissions:
if permissions not in list(MountPermissions):
raise ValueError(f"unknown filesystem permissions: {permissions}")
options += [permissions.value]
if mode:
options += [mode]
args = ["--make-private"]
if options:
args += ["-o", ",".join(options)]
r = subprocess.run(["mount"] + args + [source, target],
stderr=subprocess.STDOUT,
stdout=subprocess.PIPE,
encoding="utf-8",
check=False)
if r.returncode != 0:
code = r.returncode
msg = r.stdout.strip()
raise RuntimeError(f"{msg} (code: {code})")
self.mounts += [{"source": source, "target": target}]
def umount(self):
while self.mounts:
mnt = self.mounts.pop() # FILO: get the last mount
target = mnt["target"]
# The sync should in theory not be needed but in rare
# cases `target is busy` error has been spotted.
# Calling `sync` does not hurt so we keep it for now.
if not self.remount:
subprocess.run(["sync", "-f", target], check=True)
subprocess.run(["umount", target], check=True)
def __exit__(self, exc_type, exc_val, exc_tb):
self.umount()