Add autoskip option to hexdump and dumpstruct

[yunzheng]

This PR adds a autoskip argument to the hexdump() and dumpstruct() functions. When autoskip=True it will collapse all consecutive NULL bytes on a hexdump line to a single *. This mimics the --autoskip feature of xxd:

$ xxd -a /bin/ls | head
00000000: cafe babe 0000 0002 0100 0007 0000 0003  ................
00000010: 0000 4000 0000 bc00 0000 000e 0100 000c  ..@.............
00000020: 8000 0002 0001 0000 0001 5c00 0000 000e  ..........\.....
00000030: 0000 0000 0000 0000 0000 0000 0000 0000  ................
*
00004000: cffa edfe 0700 0001 0300 0000 0200 0000  ................
00004010: 1200 0000 c806 0000 8500 2000 0000 0000  .......... .....
00004020: 1900 0000 4800 0000 5f5f 5041 4745 5a45  ....H...__PAGEZE
00004030: 524f 0000 0000 0000 0000 0000 0000 0000  RO..............
00004040: 0000 0000 0100 0000 0000 0000 0000 0000  ................

and with dissect hexdump autoskip=True:

Note that I have also changed the hexdump() function signature to be kwargs only starting from the second argument. I think this is much cleaner and less error prone. I'm doubting if we should do the same for dumpstruct().

[codecov]

Codecov Report

❌ Patch coverage is 0% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (29652dd) to head (aae286d).

Files with missing lines	Patch %	Lines
dissect/cstruct/utils.py	0.00%	17 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #158   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files         21      21           
  Lines       2470    2482   +12     
=====================================
- Misses      2470    2482   +12     

Flag	Coverage Δ
unittests	0.00% <0.00%> (ø)

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[codspeed-hq]

Merging this PR will improve performance by 19.46%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

#### 🎉 Hooray! `pytest-codspeed` just leveled up to 5.0.2!

A heads-up, this is a breaking change and it might affect your current performance baseline a bit. But here's the exciting part - it's packed with new, cool features and promises improved result stability 🥳!
Curious about what's new? Visit our releases page to delve into all the awesome details about this new version.

⚡ 5 improved benchmarks
✅ 7 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	test_benchmark_basic[compiled]	81.2 µs	73.3 µs	+10.7%
⚡	test_benchmark_getattr_typedefs	27.5 µs	24.3 µs	+12.97%
⚡	test_benchmark_getattr_types	27 µs	23.8 µs	+13.68%
⚡	test_benchmark_getattr_constants	17 µs	13.5 µs	+26.28%
⚡	test_benchmark_attribute_access	15.3 µs	11.3 µs	+35.53%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing hexdump-autoskip (aae286d) with main (29652dd)}

[yunzheng]

@codspeedbot explain why this is faster

[Schamper]

NUL or NULL?

[yunzheng]

NUL or NULL?

xxd calls it NUL in the man page:

       -a | -autoskip
              Toggle autoskip: A single '*' replaces NUL-lines.  Default off.

Also it's not very clear in the man page, but it always leaves the first NUL(L) line intact.

[Schamper]

I'm doubting if we should do the same for dumpstruct().

Probably, yes. But that has bigger changes with #156. Perhaps we can do that in that PR.

[yunzheng]

I'm doubting if we should do the same for dumpstruct().

Probably, yes. But that has bigger changes with #156. Perhaps we can do that in that PR.

roger