How to detect calls to a SPECIFIC method in FxCop via a custom rule -- what to put in Check method

Question

I want to disallow calls to a specific method (MessageBox.Show) via a custom FxCop rule. I know the mechanics of how to get an FxCop rule custom-implemented (the XML file, inheriting from BaseIntrospectionRule, etc.) My question here is what I put in the "Check" method.

Below is the initial draft I have based on poking around a lot on the web, but I'm very puzzled as to what I would actually populate in the two fields marked with ????? below.

I'm not sure even this solution, as it exists, would work. What is the fool-proof to make sure I'm doing what I want -- which is catching all calls to MessageBox.Show?

public override ProblemCollection Check(Member member)
{
    Method method = member as Method;
    if (method == null)
    {
        return null;
    }
    MetadataCollection<Instruction>.Enumerator enumerator = method.Instructions.GetEnumerator();
    while (enumerator.MoveNext())
    {
        Instruction current = enumerator.Current;
        switch (current.OpCode)
        {
            case OpCode.Call:
            case OpCode.Callvirt:
            {
                Method method3 = current.Value as Method;
                if (method3 == **?????**)
                {
                    Problem item = new Problem(base.GetResolution(**?????**), current);
                    base.Problems.Add(item);
                }
                break;
            }
        }
    }
    return base.Problems;
}

The Instructions are 'the old way' of writing FxCop rules. It's easier to use the Visit methods instead. For a custom rule written by me that looks up calls to string.ToString (among others), see: https://fxcopcontrib.codeplex.com/SourceControl/changeset/view/7476#37972 — jessehouwing, May 03 '12 at 20:44
The best tutorial on custom rules can be found here: http://www.binarycoder.net/fxcop/index.html — jessehouwing, May 03 '12 at 20:48

score 1 · Answer 1 · answered May 03 '12 at 16:08

1

You might want to take a look at how the built-in SpecifyMessageBoxOptions rule is built using a decompiler like Reflector. There are other possible approaches, but name comparison is usually fine unless you have reason to believe that it will cause excessive false positives.

answered May 03 '12 at 16:08

Nicole Calinoiu

20,843
2
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49

I found nice examples in 'C:\Program Files (x86)\Microsoft Visual Studio 11.0\Team Tools\Static Analysis Tools\FxCop\Rules\' – Maslow Sep 21 '12 at 19:38

score 1 · Answer 2 · answered Oct 11 '13 at 00:14

How about something like this?

   public override ProblemCollection Check(Member member)
    {
        Method method = member as Method;
        if (method != null) 
        {
            this.Visit(method.Body);
        }
        return this.Problems;
    }

    public override void VisitMethodCall(MethodCall call)
    {
        base.VisitMethodCall(call);
        Method targetMethod = (Method)((MemberBinding)call.Callee).BoundMember;
        if (targetMethod.Name.Name.Contains("MessageBox.Show"))
           this.Problems.Add(new Problem(this.GetResolution(), call));
    }

How to detect calls to a SPECIFIC method in FxCop via a custom rule -- what to put in Check method

2 Answers2