fix(userspace/engine): avoid storing escaped strings in engine

[jasondellaluce]

What type of PR is this?

/kind bug

Any specific area of the project related to this PR?

/area engine

What this PR does / why we need it:

When the engine compiles list infos, we have a small bug for which we store forcefully-quoted strings in the engine's data structures instead of quoting them only at the time of their usage (at list refs resolution time). After investigating, this doesn't seem to affect the runtime-evaluated rules data structures, but it's clearly visible with the -L functionality and reproduced on list items that are YAML-escaped or contain spaces.

Example:

# rules_sample.yaml
- list: my_list
  items: [non_escaped_val, "escaped val"]

$ falco -L -o json_output=true -r rules_sample | jq .
{
  "lists": [
    {
      "details": {
        "items_compiled": [
          "non_escaped_val",
          "\"escaped val\""
        ],
        "lists": [
          "escaped val"
        ],
        "plugins": [],
        "used": false
      },
      "info": {
        "items": [
          "non_escaped_val"
        ],
        "name": "my_list"
      }
    }
  ],
  "macros": [],
  "required_engine_version": "0.0.0",
  "required_plugin_versions": [],
  "rules": []
}

Here, "escaped val" is interpreted as a list reference and is not properly escaped when printed as a value.

Which issue(s) this PR fixes:

Special notes for your reviewer:

With these changes, the same example now correctly prints as:

{
  "lists": [
    {
      "details": {
        "items_compiled": [
          "non_escaped_val",
          "escaped val"
        ],
        "lists": [],
        "plugins": [],
        "used": false
      },
      "info": {
        "items": [
          "non_escaped_val",
          "escaped val"
        ],
        "name": "my_list"
      }
    }
  ],
  "macros": [],
  "required_engine_version": "0.0.0",
  "required_plugin_versions": [],
  "rules": []
}

Does this PR introduce a user-facing change?:

fix(userspace/engine): avoid storing escaped strings in engine defs

[github-actions]

This PR may bring feature or behavior changes in the Falco engine and may require the engine version to be bumped.

Please double check userspace/engine/falco_engine_version.h file. See versioning for FALCO_ENGINE_VERSION.

/hold

[jasondellaluce]

/unhold

False positive on the engine version checks.

[Andreagit97]

LGTM! Can we add a simple unit test like the one you used in the PR description?

[jasondellaluce]

LGTM! Can we add a simple unit test like the one you used in the PR description?

Definitely! Just added one.

[Andreagit97]

/approve

[poiana]

LGTM label has been added.

Git tree hash: c8022055cdd4f1d0d1e5e9d5a5831088e1ad8c6f

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Andreagit97, jasondellaluce, LucaGuerra

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• OWNERS [Andreagit97,LucaGuerra,jasondellaluce]

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