Python script to return the last successful Time Machine backup timestamp.

tm-last-backup.py

#!/usr/bin/env python

from datetime import timedelta, tzinfo
from shlex import split
from subprocess import Popen, PIPE
import os
import plistlib

ZERO = timedelta(0)
NOT_ENABLED = u'Not enabled.'
TM_PREFS_PATH = '/Library/Preferences/com.apple.TimeMachine.plist'
TM_RESULTS_PATH = '/private/var/db/.TimeMachine.Results.plist'


class UTC(tzinfo):
    """UTC"""
    def utcoffset(self, dt):
        return ZERO

    def tzname(self, dt):
        return "UTC"

    def dst(self, dt):
        return ZERO


def render_timestamp(dt):
    if not dt.tzinfo:
        dt = dt.replace(tzinfo=UTC())
    return dt.strftime('%Y-%m-%d %H:%M:%S %z')


def popen(command):
    return Popen(split(command), stdout=PIPE).stdout.read()


def parse_plist(plist_path):
    cmd = '/usr/bin/plutil -convert xml1 -o - "%s"' % plist_path
    xml_plist = popen(cmd)
    return plistlib.readPlistFromString(xml_plist)


def get_prefs_version(prefs):
    return prefs.get('PreferencesVersion', -1)


def pre_version2_result(results):
    result = NOT_ENABLED
    if os.path.isfile(results):
        tm_status = parse_plist(results)
        if tm_status.get('BACKUP_COMPLETED_DATE'):
            result = render_timestamp(tm_status['BACKUP_COMPLETED_DATE'])
    return result


def get_tm_result(prefs, tm_pref_handler):
    result = NOT_ENABLED
    if tm_pref_handler(prefs):
        result = render_timestamp(max(tm_pref_handler(prefs)))
    return result


def v2_parser(tm_status):
    snapshot_timestamps = []
    for d in tm_status['Destinations']:
        completed = d.get('BACKUP_COMPLETED_DATE')
        if completed:
            snapshot_timestamps.append(completed)
    return snapshot_timestamps


def v3_parser(tm_status):
    snapshot_timestamps = []
    for d in tm_status['Destinations']:
        snapshot_timestamps.extend(d.get('SnapshotDates', []))
    return snapshot_timestamps


def get_tm_status(prefs, results=TM_RESULTS_PATH):
    # If the preferences plist doesn't even exist
    if not os.path.isfile(prefs):
        return u"<result>%s</result>" % NOT_ENABLED

    prefs = parse_plist(prefs)
    version = int(get_prefs_version(prefs))

    # If AutoBackup doesn't exist or isn't enabled
    if not int(prefs.get('AutoBackup', 0)):
        return u"<result>%s</result>" % NOT_ENABLED

    if version == 3:
        last_backup = get_tm_result(prefs, v3_parser)
    elif version == 2:
        last_backup = get_tm_result(prefs, v2_parser)
    else:
        last_backup = pre_version2_result(results)

    return u"<result>%s</result>" % last_backup


if __name__ == '__main__':
    print get_tm_status(TM_PREFS_PATH)