Find upgradable debian packages with major version changes

apt-majorchanges.py

#!/usr/bin/env python
"""
apt-majorchanges.py

Find upgradable debian packages with major version changes
"""

import apt

__author__ = "theirix"
__license__ = "BSD"

def normalize_version(ver):
    """Converts a debian version string to dot-separated list"""
    for sep in ['+', '-']:
        if ver.rfind(sep) != -1:
            ver = ver[0:ver.rfind(sep)]
    return ver.split('.')


def major_change(version_old, version_new):
    """Checks if two version describe a major version change"""
    try:
        vold = normalize_version(version_old)
        vnew = normalize_version(version_new)
        if len(vold) != len(vnew):
            # allow upgrade like 1.2.3 -> 1.2.3.9
            if len(vold) == len(vnew)-1 and vold == vnew[:-1]:
                return False
            # allow upgrade like 1.2.3 -> 1.2.4.9
            if len(vold) >= 3 and len(vold) == len(vnew)-1 and \
                    vold[:-1] == vnew[:-2]:
                return False
            return True
        else:
            # disallow 1.2.3 => 1.3.0
            if vold[:-1] != vnew[:-1]:
                return True
        return False
    except Exception:
        print "Wrong versions", version_old, version_new
        raise


def main():
    """Entry"""
    cache = apt.Cache()
    cache.upgrade(True)
    upgradable = cache.get_changes()
    major_upgrades = [p for p in upgradable if
                      p.is_installed and
                      major_change(p.installed.version, p.candidate.version)]
    print "Packages with major version changes:", \
        len(major_upgrades), "of", len(upgradable)
    for package in major_upgrades:
        print "   " + package.fullname + " (" + package.installed.version + \
            " => " + package.candidate.version + ")"


if __name__ == "__main__":
    main()