problem_report: enforce some keys to always have str values in load()

[bdrung]

plasmashell crashed on the system, and when Apport tried to upload the problem report, whoopsie-upload-all crashed:

INFO:root:Collecting info for /var/crash/_usr_bin_plasmashell.1000.crash...
ERROR: hook /usr/share/apport/general-hooks/generic.py crashed:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/apport/report.py", line 314, in _run_hook
    symb["add_info"](report, ui)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^
  File "/usr/share/apport/general-hooks/generic.py", line 70, in add_info
    for lib in re.finditer(r"\s(/[^ ]+\.so[.0-9]*)$", report["ProcMaps"], re.M):
               ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.14/re/__init__.py", line 285, in finditer
    return _compile(pattern, flags).finditer(string)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
TypeError: cannot use a string pattern on a bytes-like object
Traceback (most recent call last):
  File "/usr/share/apport/whoopsie-upload-all", line 246, in <module>
    main()
    ~~~~^^
  File "/usr/share/apport/whoopsie-upload-all", line 228, in main
    stamps = collect_info()
  File "/usr/share/apport/whoopsie-upload-all", line 162, in collect_info
    res = process_report(r)
  File "/usr/share/apport/whoopsie-upload-all", line 112, in process_report
    r.add_gdb_info()
    ~~~~~~~~~~~~~~^^
  File "/usr/lib/python3/dist-packages/apport/report.py", line 1057, in add_gdb_info
    addr_signature = self.crash_signature_addresses()
  File "/usr/lib/python3/dist-packages/apport/report.py", line 1797, in crash_signature_addresses
    if self["ProcMaps"].startswith("Error: "):
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
TypeError: startswith first arg must be bytes or a tuple of bytes, not str

The ProcMaps field in the crash report has following last lines:

 7f8e5d61b000-7f8e5d61e000 r-xp 00002000 fc:00 19081540                   /usr/lib/x86_64-linux-gnu/qt6/plugins/kf6/packagestructure/plasma_wallpaper.so
 7f8e5d61e000-7f8e5d61f000 r--p 00005000 fc:00 19081540                   /usr/lib/x86_64-linux-gnu/qt6/plugins/kf6/packagestructure/plasma_wallpaper.so
 7f8e5d61f000-7f8e5d620000 r--p 00005000 fc:00 190815U\0\0

So string value for ProcMaps seems to be truncated. whoopsie-upload-all opens the crash file and keeps the value as bytes because it contains null characters at the end.

The value for ProcMaps should always be a string. There are other fields that are expected to be string as well.

Enforce decoding those fields when reading the crash report and prevent setting those keys to non-string values. This should result in more consistent ProblemReport object instances. This can be accompanied by type hints in a future commit.

Bug: https://launchpad.net/bugs/2146806

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.52%. Comparing base (19cf32f) to head (3588162).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #588   +/-   ##
=======================================
  Coverage   84.51%   84.52%           
=======================================
  Files         104      104           
  Lines       20988    21000   +12     
  Branches     3218     3219    +1     
=======================================
+ Hits        17739    17751   +12     
  Misses       2808     2808           
  Partials      441      441           

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[Hyask]

Looks good in overall, just one question.

[bdrung]

Just rebased on master.

[bdrung]

Noticed this problem with this patch set:

divide-by-zero
PYTHONPATH=$(pwd) APPORT_LAUNCHPAD_INSTANCE=qastaging bin/apport-cli /var/crash/_usr_bin_divide-by-zero.1000.crash
$ PYTHONPATH=$(pwd) APPORT_LAUNCHPAD_INSTANCE=qastaging bin/apport-retrace --auth ~/.cache/apport/launchpad.credentials -S system 2143181
ERROR: Broken report: value for key Dependencies must be a string, closing as invalid

So more changes are needed.

[bdrung]

Let's split this PR into two. I rebased this PR on main and only kept "problem_report: enforce some keys to always have str values in load()".

The other two commits will be submitted in a follow-up PR once I addressed the apport-retrace issue mentioned above.