Simplify read_config

[kornelski]

Changes

read_config doesn't have to use io::Write to just copy bytes in memory.

License Acceptance

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 82.08%. Comparing base (e3893d3) to head (21e5ab5).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4458      +/-   ##
==========================================
- Coverage   82.10%   82.08%   -0.02%     
==========================================
  Files         255      255              
  Lines       31280    31257      -23     
==========================================
- Hits        25681    25656      -25     
- Misses       5599     5601       +2     

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[kornelski]

write_config already uses copy_from_slice, so changes to it would be just a code-golf.

However, I'm wondering if these functions should be reporting errors instead of just not reading/writing. Isn't there a risk from leaving data unchanged?

[ShadowCurse]

Don't think returning errors makes a lot of sense here. There are 2 paths: panic and abort the process, or log the error and continue execution. In case of read_config I assume driver will simply not initialize the device. WDYT @bchalios

[ShadowCurse]

@kornelski Also please fix compilations/stylistics errors from here: https://buildkite.com/firecracker/firecracker-pr/builds/9248#_

[bchalios]

Hi @kornelski, could you fix the style issues in the PR so we can merge this?

[roypat]

Hi @kornelski, I've gone ahead and fixed up the style issues so that we can go ahead with merging this improvement. Thanks again for your contribution!