3dbf389ebf
Rename the ChrootProcDevSys class to just Chroot and add a run() method.
Calls now can be made using:
with Chroot(root) as chroot:
chroot.run(command)
50 lines
1.9 KiB
Python
50 lines
1.9 KiB
Python
import os
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import subprocess
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class Chroot:
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"""
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Sets up mounts for the virtual filesystems inside a root tree, preparing it for running commands using chroot. This
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should be used whenever a stage needs to run a command against the root tree but doesn't support a --root option or
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similar.
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Cleans up mounts when done.
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This mounts /proc, /dev, and /sys.
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"""
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def __init__(self, root: str):
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self.root = root
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def __enter__(self):
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for d in ["/proc", "/dev", "/sys"]:
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if not os.path.exists(self.root + d):
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print(f"Making missing chroot directory: {d}")
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os.makedirs(self.root + d)
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subprocess.check_call(["/usr/bin/mount",
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"-t", "proc",
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"-o", "nosuid,noexec,nodev",
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"proc", f"{self.root}/proc"])
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subprocess.check_call(["/usr/bin/mount",
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"-t", "devtmpfs",
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"-o", "mode=0755,noexec,nosuid,strictatime",
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"devtmpfs", f"{self.root}/dev"])
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subprocess.check_call(["/usr/bin/mount",
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"-t", "sysfs",
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"-o", "nosuid,noexec,nodev",
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"sysfs", f"{self.root}/sys"])
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return self
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def __exit__(self, exc_type, exc_value, tracebk):
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failed_umounts = []
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for d in ["/proc", "/dev", "/sys"]:
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if subprocess.run(["/usr/bin/umount", "--lazy", self.root + d], check=False).returncode != 0:
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failed_umounts.append(d)
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if failed_umounts:
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print(f"Error unmounting paths from chroot: {failed_umounts}")
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def run(self, cmd, **kwargs):
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cmd = ["/usr/sbin/chroot", self.root] + cmd
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# pylint: disable=subprocess-run-check
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subprocess.run(cmd, **kwargs) # noqa: PLW1510
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