Evaluator.Parse() throws unexpected exceptions

[mschessler]

Evaluator.Parse() throws unexpected exceptions on malformed input.

Example 1:

var facade = NoStringEvaluator.CreateFacade();
var evaluator = facade.Evaluator;
evaluator.Calc("0(!(");

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index') at System.Collections.Generic.List1.get_Item(Int32 index) at NoStringEvaluating.Functions.Logic.NotAliasFunction.Execute(List1 args, ValueFactory factory) at NoStringEvaluating.NoStringEvaluator.CalcFunction(FunctionWrapperNode functionWrapper, VariablesSource variables, ValueKeeperContainer valueKeeperContainer) at NoStringEvaluating.NoStringEvaluator.CalcInternal(List1 nodes, VariablesSource variables, ValueKeeperContainer valueKeeperContainer) at NoStringEvaluating.NoStringEvaluator.OnCalcAggregated(List1 nodes, VariablesSource variables) at NoStringEvaluating.NoStringEvaluator.Calc(String formula)

Example 2: evaluator.Calc("(");

System.InvalidOperationException: Stack empty. at System.Collections.Generic.Stack1.ThrowForEmptyStack() at System.Collections.Generic.Stack1.Pop() at NoStringEvaluating.NoStringEvaluator.CalcInternal(List1 nodes, VariablesSource variables, ValueKeeperContainer valueKeeperContainer) at NoStringEvaluating.NoStringEvaluator.OnCalcAggregated(List1 nodes, VariablesSource variables) at NoStringEvaluating.NoStringEvaluator.Calc(String formula)

[KovtunV]

This is expected behavior. I did it to not to decrease performance because of function checking. Alternatively I created another service to validate formula input.

Example 1:

Example 2:

[mschessler]

Hey, thanks for the fast answer. I was not aware of the check syntax function. The problem unfortunately still remains. New inputs that pass the check function but still crash:

";;" -> System.InvalidOperationException

"-(!())" -> System.ArgumentOutOfRangeException

[KovtunV]

Thank you!

• ";;" can be fixed in FormulaChecker
• "-(!())" can be fixed it in the function NotAliasFunction and probably in FormulaChecker I should add validation as well... will think

I will fix it in the next version.

[mschessler]

Not sure how interested you are, I'm just having some fun playing around with C# Fuzzing.

So here is another one:

"LeN(2)" -> System.NullReferenceException

If you want to I will report all findings in a few days, but I understand if you say that these bugs are not that relevant.

[KovtunV]

If you share the results, I will be grateful)

On the other hand, I'm not sure should I validate functions or not. For example, "UPPER()" will throw as well, I left it to show an error immediately. I mean if exception throws user can review formula immediately, but if I will return some value, even my wrapper around null, user can realize that later