Orders API: Fix race condition in voucher redemption (Z#23230391)

The old code relied on the `Voucher.redeemed` value obtained *before*
the lock was taken, not afterwards.

The change in services/orders.py is functionally pointless, but it makes
the pattern of "fill availability only after lock" clearer and might
avoid introducing similar bugs in the future.

src/pretix/api/serializers/order.py

@@ -1412,6 +1412,7 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
         qa = QuotaAvailability()
         qa.queue(*[q for q, d in quota_diff_for_locking.items() if d > 0])
         qa.compute()
+        v_avail = {}
 
         # These are not technically correct as diff use due to the time offset applied above, so let's prevent accidental
         # use further down
@@ -1441,11 +1442,13 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
 
                 voucher_usage[v] += 1
                 if voucher_usage[v] > 0:
-                    redeemed_in_carts = CartPosition.objects.filter(
-                        Q(voucher=pos_data['voucher']) & Q(event=self.context['event']) & Q(expires__gte=now_dt)
-                    ).exclude(pk__in=[cp.pk for cp in delete_cps])
-                    v_avail = v.max_usages - v.redeemed - redeemed_in_carts.count()
-                    if v_avail < voucher_usage[v]:
+                    if v not in v_avail:
+                        v.refresh_from_db(fields=['redeemed'])
+                        redeemed_in_carts = CartPosition.objects.filter(
+                            Q(voucher=v) & Q(event=self.context['event']) & Q(expires__gte=now_dt)
+                        ).exclude(pk__in=[cp.pk for cp in delete_cps])
+                        v_avail[v] = v.max_usages - v.redeemed - redeemed_in_carts.count()
+                    if v_avail[v] < voucher_usage[v]:
                         errs[i]['voucher'] = [
                             'The voucher has already been used the maximum number of times.'
                         ]

src/pretix/api/views/checkin.py

@@ -1122,7 +1122,7 @@ class CheckinViewSet(viewsets.ReadOnlyModelViewSet):
     permission = 'event.orders:read'
 
     def get_queryset(self):
-        qs = Checkin.all.filter().select_related(
+        qs = Checkin.all.filter(list__event=self.request.event).select_related(
             "position",
             "device",
         )

src/pretix/base/modelimport.py

@@ -70,6 +70,10 @@ def parse_csv(file, length=None, mode="strict", charset=None):
         except ImportError:
             charset = file.charset
     data = data.decode(charset or "utf-8", mode)
+
+    # remove stray linebreaks from the end of the file
+    data = data.rstrip("\n")
+
     # If the file was modified on a Mac, it only contains \r as line breaks
     if '\r' in data and '\n' not in data:
         data = data.replace('\r', '\n')

src/pretix/base/services/orders.py

@@ -727,8 +727,6 @@ def _check_positions(event: Event, now_dt: datetime, time_machine_now_dt: dateti
     _check_date(event, time_machine_now_dt)
 
     products_seen = Counter()
-    q_avail = Counter()
-    v_avail = Counter()
     v_usages = Counter()
     v_budget = {}
     deleted_positions = set()
@@ -793,6 +791,9 @@ def _check_positions(event: Event, now_dt: datetime, time_machine_now_dt: dateti
                 shared_lock_objects=[event]
             )
 
+    q_avail = Counter()
+    v_avail = Counter()
+
     # Check maximum order size
     limit = min(int(event.settings.max_items_per_order), settings.PRETIX_MAX_ORDER_SIZE)
     if sum(1 for cp in sorted_positions if not cp.addon_to) > limit:

src/tests/base/test_modelimport_orders.py

@@ -991,3 +991,30 @@ def test_import_mixed_order_size_consistency(user, event, item):
         ).get()
     assert ('Inconsistent data in row 2: Column Email address contains value "a2@example.com", but for this order, '
             'the value has already been set to "a1@example.com".') in str(excinfo.value)
+
+
+@pytest.mark.django_db
+@scopes_disabled()
+def test_import_line_endings_mix(event, item, user):
+    # Ensures import works with mixed file endings.
+    # See Ticket#23230806 where a file to import ends with \r\n
+    settings = dict(DEFAULT_SETTINGS)
+    settings['item'] = 'static:{}'.format(item.pk)
+
+    cf = inputfile_factory()
+    file = cf.file
+    file.seek(0)
+    data = file.read()
+    data = data.replace(b'\n', b'\r')
+    data = data.rstrip(b'\r\r')
+    data = data + b'\r\n'
+
+    print(data)
+    cf.file.save("input.csv", ContentFile(data))
+    cf.save()
+
+    import_orders.apply(
+        args=(event.pk, cf.id, settings, 'en', user.pk)
+    )
+    assert event.orders.count() == 3
+    assert OrderPosition.objects.count() == 3