Bug 54370

Summary:	NPE mapping method in EL
Product:	Tomcat 7	Reporter:	Remy Maucherat <remm>
Component:	Jasper	Assignee:	Tomcat Developers Mailing List <dev>
Status:	RESOLVED FIXED
Severity:	normal
Priority:	P2
Version:	trunk
Target Milestone:	---
Hardware:	PC
OS:	Linux
Attachments:	Patch

Description Remy Maucherat 2013-01-03 14:20:38 UTC

Created attachment 29808 [details]
Patch

NPE when using null parameters in some cases: https://issues.jboss.org/browse/AS7-3177

I did put a workaround for it, but I don't know how legitimate it is. It looks a bit similar to the NPE with a null toString that got reverted, where a null object is used as an argument.

Comment 1 Mark Thomas 2013-01-03 14:39:47 UTC

I think you have identified a problem but I'm not sure the proposed solution is correct. Treating a null as an exact match for a parameter seems wrong. I think it needs to be treated as a possible match. I'll work on some test cases.

Comment 2 Remy Maucherat 2013-01-03 14:55:00 UTC

(In reply to comment #1)
> I think you have identified a problem but I'm not sure the proposed solution
> is correct. Treating a null as an exact match for a parameter seems wrong. I
> think it needs to be treated as a possible match. I'll work on some test
> cases.

I think it is suspicious too [like many one line patches], but even if it goes through ELSupport.coerceToType, I think null looks like it will always end up matching the expected type (unless I missed something).

Comment 3 Mark Thomas 2013-01-03 15:39:59 UTC

It is the exact match part that is the problem. As soon as an exact match is find, Tomcat stops looking. With a null parameter type it needs to keep looking as it is only a possible match. Tomcat needs to ensure it is the only possible match and that there aren't ambiguous matches.

I fixed this in trunk and 7.0.x and it will be included in 7.0.35 onwards.

Comment 4 Remy Maucherat 2013-01-03 17:22:59 UTC

Thanks, very nice improvement.