upgrades: Check before starting dist upgrade process

Signed-off-by: James Valleroy <jvalleroy@mailbox.org>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>

actions/upgrades

@@ -93,8 +93,6 @@ def parse_arguments():
     subparsers.add_parser('get-log', help='Print the automatic upgrades log')
 
     subparsers.add_parser('setup', help='Setup apt preferences')
-    subparsers.add_parser('start-dist-upgrade',
-                          help='Start dist upgrade process')
 
     activate_backports = subparsers.add_parser(
         'activate-backports', help='Activate backports if possible')
@@ -102,11 +100,12 @@ def parse_arguments():
                                     action='store_true',
                                     help='Development mode')
 
-    dist_upgrade = subparsers.add_parser(
-        'dist-upgrade', help='Perform dist upgrade if possible')
-    dist_upgrade.add_argument('--test', required=False, default=False,
-                              action='store_true',
-                              help='Test dist-upgrade from stable to testing')
+    start_dist_upgrade = subparsers.add_parser(
+        'start-dist-upgrade', help='Check and start dist upgrade process')
+    start_dist_upgrade.add_argument(
+        '--test', required=False, default=False, action='store_true',
+        help='Test dist-upgrade from stable to testing')
+    subparsers.add_parser('dist-upgrade', help='Perform dist upgrade')
 
     subparsers.required = True
     return parser.parse_args()
@@ -294,22 +293,21 @@ def _add_apt_preferences():
             file_handle.write(APT_PREFERENCES_APPS)
 
 
-def _check_and_dist_upgrade(test_upgrade=False):
+def _check_dist_upgrade(test_upgrade=False):
     """Check for new stable release. If there is one, and updates are
-    enabled, perform dist-upgrade.
+    enabled, return True.
 
-    If test_upgrade is True, perform upgrade to testing if possible.
+    If test_upgrade is True, also check for upgrade to testing.
     """
     if dist_upgrade_flag.exists():
-        print('Continuing previously interrupted dist-upgrade.')
-        _perform_dist_upgrade()
-        return
+        print('Found previously interrupted dist-upgrade.')
+        return True
 
     release, dist = get_current_release()
     if release in ['unstable', 'testing']:
         print(f'System release is {release}. Skip checking for new stable '
               'release.')
-        return
+        return False
 
     check_dists = ['stable']
     if test_upgrade:
@@ -335,27 +333,27 @@ def _check_and_dist_upgrade(test_upgrade=False):
 
     if not codename:
         print('"Codename:" not found in release file.')
-        return
+        return False
 
     if codename == dist:
         print(f'{dist} is already the latest release.')
-        return
+        return False
 
     if not _check_auto():
         print('Automatic updates are not enabled.')
-        return
+        return False
 
     if check_dist == 'testing' and not test_upgrade:
         print(f'Skipping dist-upgrade to {check_dist} since --test is not '
               'set.')
-        return
+        return False
 
     output = subprocess.check_output(['df', '--output=avail,pcent', '/'])
     output = output.decode().split('\n')[1].split()
     free_space, free_percent = int(output[0]), int(output[1][:-1])
     if free_space < 1000000 or free_percent < 10:
         print('Not enough free space in /.')
-        return
+        return False
 
     print(f'Upgrading from {dist} to {codename}...')
     with open(SOURCES_LIST, 'r') as sources_list:
@@ -377,7 +375,7 @@ def _check_and_dist_upgrade(test_upgrade=False):
 
     print('Dist upgrade in progress. Setting flag.')
     dist_upgrade_flag.touch(mode=0o660)
-    _perform_dist_upgrade()
+    return True
 
 
 def _perform_dist_upgrade():
@@ -452,22 +450,23 @@ def subcommand_activate_backports(arguments):
     _check_and_backports_sources(arguments.develop)
 
 
-def subcommand_start_dist_upgrade(_):
-    """Start dist upgrade process."""
-    subprocess.Popen(['systemctl', 'start', 'freedombox-dist-upgrade'],
-                     stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL,
-                     stderr=subprocess.DEVNULL, close_fds=True,
-                     start_new_session=True)
-
-
-def subcommand_dist_upgrade(arguments):
-    """Perform major distribution upgrade.
-
-    Check if a new stable release is available, and perform dist-upgrade if
-    updates are enabled.
+def subcommand_start_dist_upgrade(arguments):
+    """Start dist upgrade process.
 
+    Check if a new stable release is available, and start dist-upgrade process
+    if updates are enabled.
     """
-    _check_and_dist_upgrade(arguments.test)
+    if _check_dist_upgrade(arguments.test):
+        subprocess.Popen(['systemctl', 'start', 'freedombox-dist-upgrade'],
+                         stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL,
+                         stderr=subprocess.DEVNULL, close_fds=True,
+                         start_new_session=True)
+
+
+def subcommand_dist_upgrade(_):
+    """Perform major distribution upgrade.
+    """
+    _perform_dist_upgrade()
 
 
 def main():