add `utcnow()` helper function to avoid `datetime.utcnow()`

`datetime.utcnow()` is deprecated since Python 3.12. This causes additional lines of
output and thus breaks the test suite. I was not sure if all borg internals are
ready to deal with timezone-aware datetime instances so tried to keep the changes
minimal.

6 files changed, 22 insertions, 15 deletions

diff --git a/src/borg/archive.py b/src/borg/archive.py
index 39c8fcd42..9c60b611a 100644
--- a/src/borg/archive.py
+++ b/src/borg/archive.py
@@ -6,7 +6,7 @@ import sys
 import time
 from collections import OrderedDict
 from contextlib import contextmanager
-from datetime import datetime, timezone, timedelta
+from datetime import timezone, timedelta
 from functools import partial
 from getpass import getuser
 from io import BytesIO
@@ -42,6 +42,7 @@ from .helpers import os_open, flags_normal, flags_dir
 from .helpers import os_stat
 from .helpers import msgpack
 from .helpers import sig_int
+from .helpers import utcnow
 from .lrucache import LRUCache
 from .patterns import PathPrefixPattern, FnmatchPattern, IECommand
 from .item import Item, ArchiveItem, ItemDiff
@@ -458,13 +459,13 @@ class Archive:
         self.noxattrs = noxattrs
         assert (start is None) == (start_monotonic is None), 'Logic error: if start is given, start_monotonic must be given as well and vice versa.'
         if start is None:
-            start = datetime.utcnow()
+            start = utcnow()
             start_monotonic = time.monotonic()
         self.chunker_params = chunker_params
         self.start = start
         self.start_monotonic = start_monotonic
         if end is None:
-            end = datetime.utcnow()
+            end = utcnow()
         self.end = end
         self.consider_part_files = consider_part_files
         self.pipeline = DownloadPipeline(self.repository, self.key)
@@ -613,7 +614,7 @@ Utilization of max. archive size: {csize_max:.0%}
         self.items_buffer.flush(flush=True)
         duration = timedelta(seconds=time.monotonic() - self.start_monotonic)
         if timestamp is None:
-            end = datetime.utcnow()
+            end = utcnow()
             start = end - duration
         else:
             end = timestamp + duration
@@ -2266,7 +2267,7 @@ class ArchiveRecreater:
             target.rename(archive.name)
         if self.stats:
             target.start = _start
-            target.end = datetime.utcnow()
+            target.end = utcnow()
             log_multi(DASHES,
                       str(target),
                       DASHES,
diff --git a/src/borg/archiver.py b/src/borg/archiver.py
index c990c90f0..ccd297dc3 100644
--- a/src/borg/archiver.py
+++ b/src/borg/archiver.py
@@ -53,7 +53,7 @@ try:
     from .helpers import format_timedelta, format_file_size, parse_file_size, format_archive
     from .helpers import safe_encode, remove_surrogates, bin_to_hex, prepare_dump_dict, eval_escapes
     from .helpers import interval, prune_within, prune_split, PRUNING_PATTERNS
-    from .helpers import timestamp
+    from .helpers import timestamp, utcnow
     from .helpers import get_cache_dir, os_stat
     from .helpers import Manifest, AI_HUMAN_SORT_KEYS
     from .helpers import hardlinkable
@@ -649,7 +649,7 @@ class Archiver:
         self.noxattrs = args.noxattrs
         self.exclude_nodump = args.exclude_nodump
         dry_run = args.dry_run
-        t0 = datetime.utcnow()
+        t0 = utcnow()
         t0_monotonic = time.monotonic()
         logger.info('Creating archive at "%s"' % args.location.processed)
         if not dry_run:
@@ -1746,7 +1746,7 @@ class Archiver:
         return self.exit_code
 
     def _import_tar(self, args, repository, manifest, key, cache, tarstream):
-        t0 = datetime.utcnow()
+        t0 = utcnow()
         t0_monotonic = time.monotonic()
 
         archive = Archive(repository, key, manifest, args.location.archive, cache=cache,
diff --git a/src/borg/helpers/manifest.py b/src/borg/helpers/manifest.py
index 84871f736..5b595eacb 100644
--- a/src/borg/helpers/manifest.py
+++ b/src/borg/helpers/manifest.py
@@ -13,7 +13,7 @@ logger = create_logger()
 
 from .datastruct import StableDict
 from .parseformat import bin_to_hex, safe_encode, safe_decode
-from .time import parse_timestamp
+from .time import parse_timestamp, utcnow
 from .. import shellpattern
 from ..constants import *  # NOQA
 
@@ -242,11 +242,11 @@ class Manifest:
             self.config[b'tam_required'] = True
         # self.timestamp needs to be strictly monotonically increasing. Clocks often are not set correctly
         if self.timestamp is None:
-            self.timestamp = datetime.utcnow().strftime(ISO_FORMAT)
+            self.timestamp = utcnow().strftime(ISO_FORMAT)
         else:
             prev_ts = self.last_timestamp
             incremented = (prev_ts + timedelta(microseconds=1)).strftime(ISO_FORMAT)
-            self.timestamp = max(incremented, datetime.utcnow().strftime(ISO_FORMAT))
+            self.timestamp = max(incremented, utcnow().strftime(ISO_FORMAT))
         # include checks for limits as enforced by limited unpacker (used by load())
         assert len(self.archives) <= MAX_ARCHIVES
         assert all(len(name) <= 255 for name in self.archives)
diff --git a/src/borg/helpers/time.py b/src/borg/helpers/time.py
index 8b48076f7..776c29033 100644
--- a/src/borg/helpers/time.py
+++ b/src/borg/helpers/time.py
@@ -10,6 +10,11 @@ def to_localtime(ts):
     return datetime(*time.localtime((ts - datetime(1970, 1, 1, tzinfo=timezone.utc)).total_seconds())[:6])
 
 
+def utcnow():
+    """Returns a naive datetime instance representing the time in the UTC timezone"""
+    return datetime.now(timezone.utc).replace(tzinfo=None)
+
+
 def parse_timestamp(timestamp, tzinfo=timezone.utc):
     """Parse a ISO 8601 timestamp string"""
     fmt = ISO_FORMAT if '.' in timestamp else ISO_FORMAT_NO_USECS
diff --git a/src/borg/repository.py b/src/borg/repository.py
index 0f20d9102..9c0284831 100644
--- a/src/borg/repository.py
+++ b/src/borg/repository.py
@@ -8,7 +8,6 @@ import time
 from binascii import hexlify, unhexlify
 from collections import defaultdict
 from configparser import ConfigParser
-from datetime import datetime
 from functools import partial
 from itertools import islice
 
@@ -21,6 +20,7 @@ from .helpers import bin_to_hex
 from .helpers import secure_erase, safe_unlink
 from .helpers import Manifest
 from .helpers import msgpack
+from .helpers import utcnow
 from .locking import Lock, LockError, LockErrorT
 from .logger import create_logger
 from .lrucache import LRUCache
@@ -634,7 +634,7 @@ class Repository:
         if self.append_only:
             with open(os.path.join(self.path, 'transactions'), 'a') as log:
                 print('transaction %d, UTC time %s' % (
-                      transaction_id, datetime.utcnow().strftime(ISO_FORMAT)), file=log)
+                      transaction_id, utcnow().strftime(ISO_FORMAT)), file=log)
 
         # Write hints file
         hints_name = 'hints.%d' % transaction_id
diff --git a/src/borg/testsuite/archiver.py b/src/borg/testsuite/archiver.py
index 0d0752b5c..2dc2bf5d3 100644
--- a/src/borg/testsuite/archiver.py
+++ b/src/borg/testsuite/archiver.py
@@ -46,6 +46,7 @@ from ..helpers import bin_to_hex
 from ..helpers import MAX_S
 from ..helpers import msgpack
 from ..helpers import flags_noatime, flags_normal
+from ..helpers import utcnow
 from ..nanorst import RstToTextLazy, rst_to_terminal
 from ..patterns import IECommand, PatternMatcher, parse_pattern
 from ..item import Item, ItemDiff, chunks_contents_equal
@@ -4048,7 +4049,7 @@ class ManifestAuthenticationTest(ArchiverTestCaseBase):
                 'version': 1,
                 'archives': {},
                 'config': {},
-                'timestamp': (datetime.utcnow() + timedelta(days=1)).strftime(ISO_FORMAT),
+                'timestamp': (utcnow() + timedelta(days=1)).strftime(ISO_FORMAT),
             })))
             repository.commit(compact=False)
 
@@ -4060,7 +4061,7 @@ class ManifestAuthenticationTest(ArchiverTestCaseBase):
             repository.put(Manifest.MANIFEST_ID, key.encrypt(msgpack.packb({
                 'version': 1,
                 'archives': {},
-                'timestamp': (datetime.utcnow() + timedelta(days=1)).strftime(ISO_FORMAT),
+                'timestamp': (utcnow() + timedelta(days=1)).strftime(ISO_FORMAT),
             })))
             repository.commit(compact=False)