lscpu: Support extracting and outputting nested fields

[alxndrv]

lscpu should be capable of outputting nested information. When using human-readable output this is achieved simply using indentation, where as in JSON mode nested fields go under the children property.

Core changes:

• Modified CpuInfo to be a recursive structure, allowing for nesting of entries through the children property.
• Moved output logic into its own function, adding support for printing out nested values, and ensuring the values on the right are aligned to the same column.
• Implemented a helper function for extracting arbitrary values from /proc/cpuinfo, using a dynamically constructed Regex.
• Added support for some basic fields like Vendor ID, CPU Family and Model, to illustrate how the aforementioned changes can be used in action.
• Added missing -J shorthand counterpart to the --json option.

Output:

CPU(s):          16
Architecture:    x86_64
  Address sizes: 48 bits physical, 48 bits virtual
  Byte Order:    Little Endian
Vendor ID:       AuthenticAMD
  Model name:    AMD Ryzen 7 7700X 8-Core Processor
    CPU Family:  25
    Model:       97

[cakebaker]

The rest looks good. Some tests would be nice ;-)

[alxndrv]

The rest looks good. Some tests would be nice ;-)

Thanks for the review. Moved the code around a bit as you suggested, and added a basic test for non-JSON output. One thing to note is that with these changes, lscpu becomes explicitly dependent on Linux, since the tests expect that we can read information from /sys/ and /proc/cpuinfo, which aren't available on other systems.

I've gone ahead and added flags to the tests so they only get executed on Linux builds. Let me know if you have better ideas for a long-term approach 🙂

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.00%. Comparing base (b6a4bfd) to head (95d57eb).
Report is 12 commits behind head on main.

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[cakebaker]

Thanks!

I've gone ahead and added flags to the tests so they only get executed on Linux builds. Let me know if you have better ideas for a long-term approach

The long-term approach is probably to use a crate like sysinfo that supports multiple platforms.