458df8695f
- Add optional bind_mounts parameter to __init__ method; - Enhanced methods to accept an optional `bind_mounts`. This allows for more flexible for configurations when setting up bind mounts. Signed-off-by: Renata Ravanelli <rravanel@redhat.com>
61 lines
2.3 KiB
Python
61 lines
2.3 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, bind_mounts=None):
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self.root = root
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self._bind_mounts = bind_mounts or []
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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.run(["mount", "-t", "proc", "-o", "nosuid,noexec,nodev",
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"proc", f"{self.root}/proc"],
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check=True)
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subprocess.run(["mount", "-t", "devtmpfs", "-o", "mode=0755,noexec,nosuid,strictatime",
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"devtmpfs", f"{self.root}/dev"],
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check=True)
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subprocess.run(["mount", "-t", "sysfs", "-o", "nosuid,noexec,nodev",
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"sysfs", f"{self.root}/sys"],
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check=True)
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for d in self._bind_mounts:
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target_path = os.path.join(self.root, d.lstrip("/"))
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if not os.path.exists(target_path):
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print(f"Making missing chroot directory: {d}")
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os.makedirs(target_path)
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subprocess.run(["mount", "--rbind", d, target_path], check=True)
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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(["umount", "--lazy", self.root + d], check=False).returncode != 0:
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failed_umounts.append(d)
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for d in self._bind_mounts[::-1]:
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target_path = os.path.join(self.root, d.lstrip("/"))
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if subprocess.run(["umount", "--lazy", target_path], 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 = ["chroot", self.root] + cmd
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# pylint: disable=subprocess-run-check
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return subprocess.run(cmd, **kwargs) # noqa: PLW1510
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