upgrades: Overhaul detection of distribution

- Move some utilities to utils.py from distupgrade.py and __init__.py.

- This fixes issues with apt preferences being set on unstable
distribution (despite code that tries to prevent it).

- There is no way to distinguish between 'testing' and 'unstable' distributions
in Debian using commands like lsb_release (powered by /etc/os-release). See:
https://lwn.net/Articles/984635/ . So, use the value set in
/etc/apt/sources.list.

Tests: (tested entire patchset)

- Deluge can be installed in trixie.

- Auto-distribution upgrade button is checked during setup on stable and
oldstable but not on testing and unstable.

- Auto-distribution upgrade button is enabled in the form on stable and
oldstable but not on testing and unstable.

- Backports wizard step is skipped on unstable (non-develop mode), but not on
oldstable, stable, testing, and unstable (develop mode).

- If backports are not activated during first wizard, then backports can be
activated on upgrades app page if distribution is oldstable, stable, testing, or
unstable (non-develop mode) but not unstable (develop mode).

- During re-run of setup, setting up backport sources is skipped if already
setup.

- Backports sources files are not added in testing (non-develop) and
unstable (non-develop) distributions. Backports sources are added to oldstable,
stable, testing (develop) and unstable (develop). Unstable sources sources are
not added to unstable but added to oldstable, stable, and testing.

- Backports sources file is added with correct code name bookworm/trixie for
oldstable, stable, and testing distributions.

- When backports sources is set to 'bookworm-backports' on Trixie distribution,
re-running setup updates them to 'trixie-backports'.

- Preferences files are added in oldstable, stable, and testing distributions
but not unstable.

- If unstable and another distro is present in apt sources, then it is treated
as unstable as shown in the distribution upgrade page.

- Current codename is shown properly from sources.list in oldstable, stable,
testing, and unstable in distribution upgrade page.

- NOT TESTED: If distribution upgrade is interrupted, then continue page is
shown.

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

plinth/modules/deluge/__init__.py

@@ -11,7 +11,7 @@ from plinth.modules.apache.components import Webserver
 from plinth.modules.backups.components import BackupRestore
 from plinth.modules.firewall.components import (Firewall,
                                                 FirewallLocalProtection)
-from plinth.modules.upgrades import get_current_release
+from plinth.modules.upgrades.utils import get_current_release
 from plinth.modules.users import add_user_to_share_group
 from plinth.modules.users.components import UsersAndGroups
 from plinth.package import Packages

plinth/modules/upgrades/__init__.py

@@ -20,7 +20,7 @@ from plinth.diagnostic_check import DiagnosticCheck, Result
 from plinth.modules.backups.components import BackupRestore
 from plinth.package import Packages
 
-from . import distupgrade, manifest, privileged
+from . import distupgrade, manifest, privileged, utils
 
 first_boot_steps = [
     {
@@ -350,21 +350,12 @@ def is_backports_enabled():
     return os.path.exists(privileged.BACKPORTS_SOURCES_LIST)
 
 
-def get_current_release():
-    """Return current release and codename as a tuple."""
-    output = subprocess.check_output(
-        ['lsb_release', '--release', '--codename',
-         '--short']).decode().strip()
-    lines = output.split('\n')
-    return lines[0], lines[1]
-
-
 def is_backports_current():
     """Return whether backports are enabled for the current release."""
     if not is_backports_enabled():
         return False
 
-    _, dist = get_current_release()
+    _, dist = utils.get_current_release()
     dist += '-backports'
     sources = sourceslist.SourcesList()
     for source in sources:
@@ -379,15 +370,12 @@ def can_activate_backports():
     if cfg.develop:
         return True
 
-    # Release will be 'n/a' in latest unstable and testing distributions.
-    release, _ = get_current_release()
-    return release not in ['unstable', 'testing', 'n/a']
+    return not utils.is_distribution_rolling()
 
 
 def can_enable_dist_upgrade():
     """Return whether dist upgrade can be enabled."""
-    release, _ = get_current_release()
-    return release not in ['unstable', 'testing', 'n/a']
+    return not utils.is_distribution_rolling()
 
 
 def _diagnose_held_packages():

plinth/modules/upgrades/distupgrade.py

@@ -105,30 +105,6 @@ def _sources_list_update(old_codename: str, new_codename: str):
     aug_path.rename(temp_sources_list)
 
 
-def _get_sources_list_codename() -> str | None:
-    """Return the codename set in the /etc/apt/sources.list file."""
-    aug = augeas.Augeas(flags=augeas.Augeas.NO_LOAD +
-                        augeas.Augeas.NO_MODL_AUTOLOAD)
-    aug.transform('aptsources', str(sources_list))
-    aug.set('/augeas/context', '/files' + str(sources_list))
-    aug.load()
-
-    dists = set()
-    for match_ in aug.match('*'):
-        dist = aug.get(match_ + '/distribution')
-        if not dist:
-            continue
-
-        dist = dist.removesuffix('-updates')
-        dist = dist.removesuffix('-security')
-        dists.add(dist)
-
-    if len(dists) != 1:
-        return None
-
-    return dists.pop()
-
-
 def get_status() -> dict[str, bool | str | None]:
     """Check if a distribution upgrade be performed.
 
@@ -158,7 +134,7 @@ def get_status() -> dict[str, bool | str | None]:
     has_free_space = utils.is_sufficient_free_space()
     running = action_utils.service_is_running('freedombox-dist-upgrade')
 
-    current_codename = _get_sources_list_codename()
+    current_codename = utils.get_sources_list_codename()
     status = {
         'updates_enabled': updates_enabled,
         'dist_upgrade_enabled': dist_upgrade_enabled,
@@ -177,7 +153,7 @@ def get_status() -> dict[str, bool | str | None]:
     if current_codename in (None, 'testing', 'unstable'):
         return status
 
-    _, base_files_codename = upgrades.get_current_release()
+    _, base_files_codename = utils.get_current_release()
     if current_codename == 'stable':
         current_codename = base_files_codename
 

plinth/modules/upgrades/privileged.py

@@ -158,8 +158,7 @@ def _check_and_backports_sources(develop=False):
     if os.path.exists(old_sources_list):
         os.remove(old_sources_list)
 
-    from plinth.modules.upgrades import (get_current_release,
-                                         is_backports_current)
+    from plinth.modules.upgrades import is_backports_current
     if is_backports_current():
         logging.info('Repositories list up-to-date. Skipping update.')
         return
@@ -181,15 +180,16 @@ def _check_and_backports_sources(develop=False):
                      'backports.')
         return
 
-    release, dist = get_current_release()
-    if release in ['unstable', 'testing', 'n/a'] and not develop:
-        logging.info(f'System release is {release}. Skip enabling backports.')
+    if utils.is_distribution_rolling() and not develop:
+        logging.info(
+            'System release is unstable/testing. Skip enabling backports.')
         return
 
     protocol = utils.get_http_protocol()
     if protocol == 'tor+http':
         logging.info('Package download over Tor is enabled.')
 
+    _, dist = utils.get_current_release()
     if not utils.is_release_file_available(protocol, dist, backports=True):
         logging.info(
             f'Release file for {dist}-backports is not available yet.')
@@ -212,13 +212,12 @@ def _add_apt_preferences():
     # Don't try to remove 50freedombox3.pref as this file is shipped with the
     # Debian package and is removed using maintainer scripts.
 
-    from plinth.modules.upgrades import get_current_release
-    _, dist = get_current_release()
-    if dist == 'sid':
+    if utils.is_distribution_unstable():
         logging.info(
-            f'System distribution is {dist}. Skip setting apt preferences '
+            'System distribution is "unstable". Skip setting apt preferences '
             'for backports.')
     else:
+        _, dist = utils.get_current_release()
         logging.info(f'Setting apt preferences for {dist}-backports.')
         with open(base_path / '50freedombox4.pref', 'w',
                   encoding='utf-8') as file_handle:

plinth/modules/upgrades/tests/test_distupgrade.py

@@ -80,43 +80,9 @@ deb https://deb.debian.org/debian bookwormish main
         assert temp_sources_list.read_text() == modified
 
 
-def test_get_sources_list_codename(tmp_path):
-    """Test retrieving codename from sources.list file."""
-    list1 = '''
-deb http://deb.debian.org/debian bookworm main non-free-firmware
-deb-src http://deb.debian.org/debian bookworm main non-free-firmware
-
-deb http://deb.debian.org/debian bookworm-updates main non-free-firmware
-deb-src http://deb.debian.org/debian bookworm-updates main non-free-firmware
-
-deb http://security.debian.org/debian-security/ bookworm-security main non-free-firmware
-deb-src http://security.debian.org/debian-security/ bookworm-security main non-free-firmware
-'''  # noqa: E501
-
-    list2 = '''
-deb http://deb.debian.org/debian stable main non-free-firmware
-deb-src http://deb.debian.org/debian stable main non-free-firmware
-
-deb http://deb.debian.org/debian bookworm-updates main non-free-firmware
-deb-src http://deb.debian.org/debian bookworm-updates main non-free-firmware
-
-deb http://security.debian.org/debian-security/ bookworm-security main non-free-firmware
-deb-src http://security.debian.org/debian-security/ bookworm-security main non-free-firmware
-'''  # noqa: E501
-
-    sources_list = tmp_path / 'sources.list'
-    module = 'plinth.modules.upgrades.distupgrade'
-    with patch(f'{module}.sources_list', sources_list):
-        sources_list.write_text(list1)
-        assert distupgrade._get_sources_list_codename() == 'bookworm'
-
-        sources_list.write_text(list2)
-        assert distupgrade._get_sources_list_codename() is None
-
-
 @patch('datetime.datetime')
-@patch('plinth.modules.upgrades.get_current_release')
-@patch('plinth.modules.upgrades.distupgrade._get_sources_list_codename')
+@patch('plinth.modules.upgrades.utils.get_current_release')
+@patch('plinth.modules.upgrades.distupgrade.utils.get_sources_list_codename')
 @patch('plinth.action_utils.service_is_running')
 @patch('plinth.modules.upgrades.utils.is_sufficient_free_space')
 @patch('plinth.modules.upgrades.is_dist_upgrade_enabled')

plinth/modules/upgrades/tests/test_utils.py

@@ -0,0 +1,95 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+"""
+Test various upgrade related utilities.
+"""
+
+from unittest.mock import patch
+
+from .. import utils
+
+
+def test_get_sources_list_codename(tmp_path):
+    """Test retrieving codename from sources.list file."""
+    list1 = '''
+deb http://deb.debian.org/debian bookworm main non-free-firmware
+deb-src http://deb.debian.org/debian bookworm main non-free-firmware
+
+deb http://deb.debian.org/debian bookworm-updates main non-free-firmware
+deb-src http://deb.debian.org/debian bookworm-updates main non-free-firmware
+
+deb http://security.debian.org/debian-security/ bookworm-security main non-free-firmware
+deb-src http://security.debian.org/debian-security/ bookworm-security main non-free-firmware
+'''  # noqa: E501
+
+    list2 = '''
+deb http://deb.debian.org/debian stable main non-free-firmware
+deb-src http://deb.debian.org/debian stable main non-free-firmware
+
+deb http://deb.debian.org/debian bookworm-updates main non-free-firmware
+deb-src http://deb.debian.org/debian bookworm-updates main non-free-firmware
+
+deb http://security.debian.org/debian-security/ bookworm-security main non-free-firmware
+deb-src http://security.debian.org/debian-security/ bookworm-security main non-free-firmware
+'''  # noqa: E501
+
+    list3 = '''
+deb http://deb.debian.org/debian unstable main
+deb http://deb.debian.org/debian trixie main
+'''
+    list4 = '''
+deb http://deb.debian.org/debian sid main
+deb http://deb.debian.org/debian trixie main
+'''
+    list5 = '''
+deb http://deb.debian.org/debian testing main
+deb http://deb.debian.org/debian trixie main
+'''
+
+    sources_list = tmp_path / 'sources.list'
+    module = 'plinth.modules.upgrades.utils'
+    with patch(f'{module}.sources_list', sources_list):
+        sources_list.write_text(list1)
+        assert utils.get_sources_list_codename() == 'bookworm'
+
+        sources_list.write_text(list2)
+        assert utils.get_sources_list_codename() is None
+
+        sources_list.write_text(list3)
+        assert utils.get_sources_list_codename() == 'unstable'
+
+        sources_list.write_text(list4)
+        assert utils.get_sources_list_codename() == 'unstable'
+
+        sources_list.write_text(list5)
+        assert utils.get_sources_list_codename() == 'testing'
+
+
+@patch('subprocess.check_output')
+def test_get_current_release(check_output):
+    """Test that getting current release works."""
+    check_output.return_value = b'test-release\ntest-codename\n\n'
+    assert utils.get_current_release() == ('test-release', 'test-codename')
+
+
+@patch('plinth.modules.upgrades.utils.get_sources_list_codename')
+def test_is_distribution_unstable(get_sources_list_codename):
+    """Test that checking for unstable distribution works."""
+    get_sources_list_codename.return_value = 'unstable'
+    assert utils.is_distribution_unstable()
+
+    get_sources_list_codename.return_value = 'sid'
+    assert utils.is_distribution_unstable()
+
+    get_sources_list_codename.return_value = 'testing'
+    assert not utils.is_distribution_unstable()
+
+
+@patch('plinth.modules.upgrades.utils.get_current_release')
+def test_is_distribution_rolling(get_current_release):
+    """Test that checking for testing/unstable distribution works."""
+    for value in ['unstable', 'testing', 'n/a']:
+        get_current_release.return_value = (value, None)
+        assert utils.is_distribution_rolling()
+
+    get_current_release.return_value = ('forky', None)
+    assert not utils.is_distribution_rolling()

plinth/modules/upgrades/utils.py

@@ -1,9 +1,12 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 """Utilities for regular updates and dist-upgrades."""
 
+import pathlib
 import re
 import subprocess
 
+import augeas
+
 from plinth.modules.apache.components import check_url
 
 RELEASE_FILE_URL = \
@@ -11,6 +14,8 @@ RELEASE_FILE_URL = \
 
 DIST_UPGRADE_REQUIRED_FREE_SPACE = 5000000
 
+sources_list = pathlib.Path('/etc/apt/sources.list')
+
 
 def check_auto() -> bool:
     """Return whether automatic updates are enabled."""
@@ -60,3 +65,62 @@ def is_sufficient_free_space() -> bool:
     output = subprocess.check_output(['df', '--output=avail', '/'])
     free_space = int(output.decode().split('\n')[1])
     return free_space >= DIST_UPGRADE_REQUIRED_FREE_SPACE
+
+
+def get_sources_list_codename() -> str | None:
+    """Return the codename set in the /etc/apt/sources.list file."""
+    aug = augeas.Augeas(flags=augeas.Augeas.NO_LOAD +
+                        augeas.Augeas.NO_MODL_AUTOLOAD)
+    aug.transform('aptsources', str(sources_list))
+    aug.set('/augeas/context', '/files' + str(sources_list))
+    aug.load()
+
+    dists = set()
+    for match_ in aug.match('*'):
+        dist = aug.get(match_ + '/distribution')
+        if not dist:
+            continue
+
+        dist = dist.removesuffix('-updates')
+        dist = dist.removesuffix('-security')
+        dists.add(dist)
+
+    if 'unstable' in dists or 'sid' in dists:
+        return 'unstable'
+
+    if 'testing' in dists:
+        return 'testing'
+
+    # Multiple distributions are not understood.
+    if len(dists) != 1:
+        return None
+
+    return dists.pop()
+
+
+def get_current_release():
+    """Return current release and codename as a tuple."""
+    output = subprocess.check_output(
+        ['lsb_release', '--release', '--codename',
+         '--short']).decode().strip()
+    lines = output.split('\n')
+    return lines[0], lines[1]
+
+
+def is_distribution_unstable() -> bool:
+    """Return whether the current distribution is unstable.
+
+    There is no way to distinguish between 'testing' and 'unstable'
+    distributions in Debian using commands like lsb_release (powered by
+    /etc/os-release). See: https://lwn.net/Articles/984635/ . So, use the value
+    set in /etc/apt/sources.list.
+    """
+    codename = get_sources_list_codename()
+    return codename in ['unstable', 'sid']
+
+
+def is_distribution_rolling() -> bool:
+    """Return whether the current distribution is testing or unstable."""
+    # Release will be 'n/a' in latest unstable and testing distributions.
+    release, _ = get_current_release()
+    return release in ['unstable', 'testing', 'n/a']