[jira] [Comment Edited] (WW-3956) (nearly) silent failure of filter initialization if struts.action.excludePattern contains invalid regexp

[Horváth, "Ákos Péter (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/WW-3956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13543713#comment-13543713 ] 

Horváth, Ákos Péter edited comment on WW-3956 at 1/4/13 9:05 AM:
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I don't get anything, not with devmode and not without. I use a recompiled, but otherways unmodified struts-core-2.3.8 with maven.

Today (CET) I will try with the original distributed binary version, and send you a minimalexample.

About the docs:

Yes, I found this, but this wasn't enough. For example, I wasn't able to find out, that ^ and $ is needed in the regexp or not. I wasn't able to find out, that it is case sensitive or not. I wasn't able to find out, that the "(a|b|c)"-like regexp matching works or not. I wasn't able to find out, how can I quote: is a single backslash enough, or I need more (because of we are in xml). And finally, I wasn't able to find out, that single "."-s are needed to be quoted if I won't an any-char match.

The first misleading, which a struts newbie finds, is that "excludePattern" is about patterns, but really they are working with regexps. My first try was a "*.js,*.css". And it will silently fail, because as regular expression these are invalid, and because of the previous problem. (Which I will yet investigate)

Finally, I could investigate all of these, and now everything works, but this required a deep dig in struts source.

And google is full with misleading information about this, and with bad examples. Google for +"struts.action.excludePattern" and you will see. Imho you need a very clear correction.
                
      was (Author: hap):
    I don't get anything, not with devmode and not without. I use a recompiled, but otherways unmodified struts-core-2.3.8 with maven.

Today (CET) I will try with the original distributed binary version, and send you a minimalexample.

About the docs:

Yes, I found this, but this wasn't enough. For example, I wasn't able to find out, that ^ and $ is needed in the regexp or not. I wasn't able to find out, that it is case sensitive or not. I wasn't able to find out, that the "(a|b|c)"-like regexp matching works or not. I wasn't able to find out, how can I quote: is a single backslash enough, or I need more (because of we are in xml). And finally, I wasn't able to find out, that single "."-s are needed to be quoted if I won't an any-char match.

The first misleading, which a struts newbie finds, is that "excludePattern" is about patterns, but really they are working with regexps. My first try was a "*.js,*.css". And it will silently fail, because as regular expression these are invalid, and because of the previous problem. (Which I will yet investigate)

Finally, I could investigate all of these, and now everything works, but this needed a deep investigation of the source of the struts core.

And google is full with misleading information about this, and with bad examples. Google for +"struts.action.excludePattern" and you will see.
                  
> (nearly) silent failure of filter initialization if struts.action.excludePattern contains invalid regexp
> --------------------------------------------------------------------------------------------------------
>
>                 Key: WW-3956
>                 URL: https://issues.apache.org/jira/browse/WW-3956
>             Project: Struts 2
>          Issue Type: Bug
>          Components: Dispatch Filter
>    Affects Versions: 2.3.8
>         Environment: all
>            Reporter: Horváth, Ákos Péter
>             Fix For: 2.3.9
>
>   Original Estimate: 1h
>  Remaining Estimate: 1h
>
> If the struts.action.excludePatterns constant contains an invalid regexp (for example, it begins with a "*"), the dispatcher can't initialize, but only an "Error filterStart" message will be logged, and the web app won't work. Imho, the expected behavior were a stack trace or a more descriptive error message.
> The cause of the problem: the buildExcludedPatternList() method of org.apache.struts2.dispatcher.ng.InitOperations builds a compiled pattern list of the comma-separated patterns given in this constant with java.util.regex.Pattern.compile() . This emits an IllegalArgumentException or a PatternSyntaxException, if invalid regexp is given, but this exception somewhere silently disappears on his way to the log.
> ---------------
> I suggest to make a minimal example in the documentation:
> ".*\.(css|js|gif|png|jpg|html)$" or "^/static/"
> is what most developer want from this constant. For me took hours to investigate this. Googling for "struts.action.excludePattern" reveals a lot of confusion about this, too. The greatest source of the confusion is that it isn't clear, and isn't anywhere documented, which is the exact regexp syntax here to apply. For example: pattern matching or regular expression, "^" and "$" are valid or not, they are needed or not, "." matches only "." or any character, etc. I think, the original inaccuracy was committed by sun, when they named a class as "Pattern", which operates with regexps. What you here can do, is a single-line minimal-example in the doc, which will explain everything.
> Thank you,
> PH

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