tutorial_sanitizer_04_function_restriction.md

Tutorial Sanitizer 04: Function Restriction

There are a set of functions that must be declared to form a valid module to be executed.

Sample Function - main()

By default, function main() must be declared so that the script has a default entry function. If you check a script without function main() in JavetSanitizerModuleFunctionChecker with the default option, you will get an error. You may create your own option with a set of new functions and the same script will pass the check.

String codeString = "function myMain() {}";
// Check the script with the default option.
try {
    new JavetSanitizerModuleFunctionChecker().check(codeString);
} catch (JavetSanitizerException e) {
    System.out.println("/******************************************************/");
    System.out.println(codeString + " // Invalid");
    System.out.println("/******************************************************/");
    System.out.println(e.getMessage());
}

// Create a new option with keyword import enabled.
JavetSanitizerOptions options = JavetSanitizerOptions.Default.toClone();
options.getReservedFunctionIdentifierSet().remove("main");
options.getReservedFunctionIdentifierSet().add("myMain");
options.seal();
// Check the script with the new option.
new JavetSanitizerModuleFunctionChecker(options).check(codeString);
System.out.println("/******************************************************/");
System.out.println(codeString + " // Valid");
System.out.println("/******************************************************/");

The output is as follows:

/******************************************************/
function myMain() {} // Invalid
/******************************************************/
Function main is not found.
/******************************************************/
function myMain() {} // Valid
/******************************************************/

The complete code is at here.