Add tests for Cilium style global variables, using named sections and non-static

[Alan-Jowett]

This pull request includes updates to the CMakeLists.txt file and the addition of a new source file src/global_variable_2.c. The changes primarily focus on adding a new global variable configuration.

Updates to CMakeLists.txt:

• Added a new object file global_variable_2.o to the add_custom_target(samples ALL list.
• Added a new custom command to generate global_variable_2.o from global_variable_2.c using clang.

Addition of src/global_variable_2.c:

• Introduced a new source file global_variable_2.c which includes macros for declaring, assigning, and accessing a global configuration variable.

Summary by CodeRabbit

• New Features
  • Introduced a dynamic configuration system that enables runtime adjustments of global settings for enhanced flexibility and optimized performance.

[coderabbitai]

Walkthrough

This update introduces a new custom build command in the CMake configuration to compile global_variable_2.c into an object file and adds macros in the C source to manage global configuration variables. The new command specifies the output, dependencies, and compilation command, while the macros provide a systematic way to declare, assign, and access a global variable defined in the source.

Changes

File Path	Change Summary
CMakeLists.txt	Added a custom command using add_custom_command to compile src/global_variable_2.c into build/global_variable_2.o.
src/global_variable_2.c	Introduced macros (DECLARE_CONFIG, ASSIGN_CONFIG, CONFIG) for global configuration management; declared and assigned a global variable with an example usage in func.

Sequence Diagram(s)

sequenceDiagram
    participant CMake
    participant Compiler
    CMake->>Compiler: Invoke compile command for global_variable_2.c
    Compiler-->>CMake: Generate global_variable_2.o

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sequenceDiagram
    participant Caller
    participant func
    participant CONFIG
    Caller->>func: Call func()
    func->>CONFIG: Access global variable via CONFIG macro
    CONFIG-->>func: Return value (10)
    func-->>Caller: Return global variable value

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Poem

In the code, a command takes flight,
Compiling sources with clang's might.
Macros declare and assign with a spin,
Global values managed from deep within.
A build refined and a config so clear—
Simple code magic, sharp and austere.

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

src/global_variable_2.c (1)

37-40: Add function documentation.

Document the purpose of this function and the expected usage of the ctx parameter.

+/**
+ * Returns the value of the global configuration variable.
+ * @param ctx The eBPF context (unused in this function)
+ * @return The current value of global_var
+ */
 int func(void* ctx) {

📜 Review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between f022799 and a96ccfb.

⛔ Files ignored due to path filters (1)

• build/global_variable_2.o is excluded by !**/*.o

📒 Files selected for processing (2)

• CMakeLists.txt (2 hunks)
• src/global_variable_2.c (1 hunks)

🔇 Additional comments (4)

src/global_variable_2.c (2)

12-31: LGTM! Well-structured macro definitions.

The macros provide a robust mechanism for declaring, assigning, and accessing global configuration variables with proper section placement and BTF declarations.

---

33-35: LGTM! Proper usage of configuration macros.

The global variable is declared with a clear description and assigned an initial value following the macro pattern.

CMakeLists.txt (2)

29-29: LGTM! Proper target addition.

The new target is correctly added to the samples dependencies in alphabetical order.

---

102-104: LGTM! Consistent custom command implementation.

The build command follows the established pattern with correct flags and dependencies.