feat(kernel): Add dmesg-like command

[theguy147]

[codecov-commenter]

Codecov Report

Merging #1732 (3118dc6) into dev (b5a1219) will decrease coverage by 0.08%.
The diff coverage is 36.58%.

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@@            Coverage Diff             @@
##              dev    #1732      +/-   ##
==========================================
- Coverage   58.63%   58.56%   -0.08%     
==========================================
  Files         175      177       +2     
  Lines       21269    21351      +82     
  Branches     1900     1910      +10     
==========================================
+ Hits        12472    12505      +33     
- Misses       8193     8243      +50     
+ Partials      604      603       -1     

Impacted Files	Coverage Δ
pwndbg/gdblib/kernel/log.py	22.85% <22.85%> (ø)
pwndbg/commands/kdmesg.py	45.65% <45.65%> (ø)
pwndbg/commands/__init__.py	75.39% <100.00%> (+0.06%)	⬆️

... and 1 file with indirect coverage changes

[disconnect3d]

Hmm:

____________________ ERROR collecting tests/test_cymbol.py _____________________
ImportError while importing test module '/pwndbg/tests/gdb-tests/tests/test_cymbol.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/lib/python3.6/importlib/__init__.py:126: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
tests/test_cymbol.py:3: in <module>
    import pwndbg.commands.cymbol
../../pwndbg/__init__.py:12: in <module>
    load_commands()
../../pwndbg/commands/__init__.py:644: in load_commands
    import pwndbg.commands.kdmesg
../../pwndbg/commands/kdmesg.py:3: in <module>
    from typing import Filter
E   ImportError: cannot import name 'Filter'

[theguy147]

I guess I was confused by the mypy hints. Previously I had the return type as a Generator but mypy complained that it is actually a Filter and therefore I just assumed that such a type is included in typing. Anyhow, I reverted the commit now.

[disconnect3d]

Can you rebase to latest dev? There's a commit increasing qemu-tests CI to 30min, maybe it will work then..

[theguy147]

latest dev introduces the following mypy error:

pwndbg/exception.py:16: error: Name "pdb" already defined (possibly by an import)  [no-redef]

don't currently have the time to investigate - might be a couple of days. but this PR is anyway not ready yet so no rush from my side. Also when I have some time I wanted to find out why the runtime of the qemu tests have exploded with the commit which introduces filtering capability of the dmesg command (which is actually not even tested yet... so shouldn't affect the test time yet)

[gsingh93]

pwndbg/exception.py:16: error: Name "pdb" already defined (possibly by an import) [no-redef]

Can you see if upgrading mypy fixes this for you? I recently upgraded the dependencies, try running this:

pip install -U -r dev-requirements.txt

[disconnect3d]

Can we just merge this? It seems that this works (?)?