how-to-add-a-new-rule.md

How to add a new rule

To instrument a new framework, you call follow the steps:

1. Create a new directory in the pkg/rules directory and create a new rule.go file

2. Register a new rule that specifies the framework import path, function name, and the function signature you want to instrument, and onEnter/onExit functions you want to insert before/after calling original function, respectively, in the rule.go file, as shown below:

   package rules
   
   func init() {
       api.NewRule("framework_name", "function_name", "function_signature", "onEnterFunc", "onExitFunc").Register()
   }

3. Implement the onEnter/onExit functions in the same directory with the rule.go file, as shown below:

   package rules
   
   import framework_name
   
   func onEnterFunc(ctx *framework_name.Context, arg1 int, arg2 bool) {
       println("onEnter")
   }
   
   func onExitFunc(ctx *framework_name.Context, ret1 string) {
       println("onExit")
   }

4. Import your new rule package by adding import statement within rule_enabler.go

There are some concrete examples in the pkg/rules directory, such as pkg/rules/test. You can refer to them for more details.