Source code for univention.updater.scripts.kernel

#!/usr/bin/python3
# SPDX-FileCopyrightText: 2020-2026 Univention GmbH
# SPDX-License-Identifier: AGPL-3.0-only
"""Prune no longer required Linux kernel packages."""

import sys
from argparse import ArgumentParser, Namespace
from os import uname

from apt import Cache


PREFIX = "linux-image-"




def main() -> None:
    opt = parse_args()
    prune(opt)





def parse_args(argv: list[str] | None = None) -> Namespace:
    parser = ArgumentParser(description=__doc__)
    parser.add_argument("--verbose", "-v", action="count", help="Increase verbosity")
    parser.add_argument("--dry-run", "-n", action="store_true", help="Only show what would be done")
    return parser.parse_args(argv)





def prune(opt: Namespace) -> None:
    cache = Cache()

    cur = {PREFIX + uname()[2] + suffix for suffix in ("", "-signed")}
    top = {
        "univention-kernel-image",
        PREFIX + "amd64",
        PREFIX + "rt-amd64",
        PREFIX + "686-pae",
        PREFIX + "686",
        PREFIX + "rt-686-pae",
    }
    meta = [
        pkg.installed
        for pkg in (cache[pkg] for pkg in top if pkg in cache)
        if pkg.is_installed
    ]
    if opt.verbose:
        print("Installed kernel meta packages:\n %s" % ("\n ".join(sorted(str(pkg) for pkg in meta)),))

    keep = required(
        cache,
        {
            dep.name
            for pkg in meta
            for alt in pkg.dependencies
            for dep in alt
            if dep.name.startswith(PREFIX)
        }
        | cur
        | top,
    )
    if opt.verbose:
        print("Exception list for kernel packages:\n %s" % ("\n ".join(sorted(keep)),))

    cache.clear()
    purge = set()
    for pkg in cache:
        if pkg.name.startswith(PREFIX) and pkg.is_installed:
            if pkg.name not in keep:
                if opt.verbose:
                    print("Purging kernel package: %s" % (pkg.name,))
                purge.add(pkg.name)
                if not opt.dry_run:
                    pkg.mark_delete(purge=True)
            else:
                if opt.verbose:
                    print("Keeping kernel package: %s" % (pkg.name, ))

    # removing a kernel package other packages depend on removes them too, e.g. the UCS role packages
    unexpected = sorted(pkg.name for pkg in cache.get_changes() if pkg.name not in purge)
    if unexpected:
        sys.exit("Aborting, purging the kernel packages would also change these packages:\n %s" % ("\n ".join(unexpected),))

    cache.commit()





def required(cache: Cache, keep: set[str]) -> set[str]:
    """Add the kernel packages installed non-kernel packages depend on, and their dependencies."""
    todo = keep | {
        dep.name
        for pkg in cache
        if pkg.is_installed and not pkg.name.startswith(PREFIX)
        for alt in pkg.installed.dependencies
        for dep in alt
        if dep.name.startswith(PREFIX)
    }
    keep = set()
    while todo:
        name = todo.pop()
        keep.add(name)
        if name in cache and cache[name].is_installed:
            todo |= {
                dep.name
                for alt in cache[name].installed.dependencies
                for dep in alt
                if dep.name.startswith(PREFIX)
            } - keep
    return keep



if __name__ == "__main__":
    main()