[DPE-7584] Fix permissions comparison

[marceloneppel]

Issue

The backups, smoke, and restore cluster tests started to fail with the following error at https://github.com/canonical/postgresql-operator/actions/runs/17796882879 because we incorrectly compare values in two different formats.

unit-postgresql-ceph-0: 10:09:12 ERROR unit.postgresql-ceph/0.juju-log __main__:
Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-postgresql-ceph-0/charm/venv/lib/python3.12/site-packages/single_kernel_postgresql/utils/postgresql.py", line 1106, in set_up_database
    cursor.execute(f"CREATE TABLESPACE temp LOCATION '{temp_location}';")
psycopg2.errors.ObjectInUse: directory "/var/snap/charmed-postgresql/common/data/temp/PG_16_202307071" already in use as a tablespace

temp_location_stats.st_mode returns 16832 and POSTGRESQL_STORAGE_PERMISSIONS returns 448 when the permissions of both are 0o700, which triggers a tablespace rename every time, even when the directory permissions are correct, leading to the above error.

Solution

Convert the output from the st_mode attribute to the same format that we retrieve from the POSTGRESQL_STORAGE_PERMISSIONS constant.

Also, I added the missing unit test (test_set_up_database_owner_and_permissions_match_no_rename_or_fix) to validate this conversion.

Checklist

• I have added or updated any relevant documentation.
• I have cleaned any remaining cloud resources from my accounts.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 46.32%. Comparing base (3ebd14c) to head (a8a9cda).
⚠️ Report is 3 commits behind head on 16/edge.

❌ Your project status has failed because the head coverage (46.32%) is below the target coverage (70.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff             @@
##           16/edge      #17      +/-   ##
===========================================
+ Coverage    46.07%   46.32%   +0.24%     
===========================================
  Files            4        4              
  Lines          803      803              
  Branches        94       94              
===========================================
+ Hits           370      372       +2     
  Misses         414      414              
+ Partials        19       17       -2     

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