Bug 55159

Summary:	Wasted work in ErrorReportValve.getPartialServletStackTrace
Product:	Tomcat 7	Reporter:	Adrian Nistor <nistor1>
Component:	Catalina	Assignee:	Tomcat Developers Mailing List <dev>
Status:	RESOLVED FIXED
Severity:	normal	CC:	nistor1
Priority:	P2	Keywords:	PatchAvailable
Version:	7.0.41
Target Milestone:	---
Hardware:	PC
OS:	Linux
Attachments:	patch patchShort

Description Adrian Nistor 2013-06-29 19:12:03 UTC

Created attachment 30499 [details]
patch

The problem appears in version 7.0.41 and in revision 1497999.  I
attached a two-line patch  (patch.diff) that fixes it.

In method "ErrorReportValve.getPartialServletStackTrace", the loop
over "elements" keeps overriding "pos" with "i".  Therefore, only the
last written value is visible out of the loop and all the other writes
and iterations are not necessary.  The patch iterates from the end of
"elements" and breaks the first time when "pos" is set.

The above fix (in patch.diff) is certainly correct (it's easy to see
through code inspection), but I think we can have an even shorter
patch (one line, in patchShort.diff): just break as soon as "pos" is
set, without reversion the loop order.  patchShort.diff is correct
only if there can be only one "elements[i]" with class name
"org.apache.catalina.core.ApplicationFilterChain" and method name
"internalDoFilter" or if it doesn't matter which such "elements[i]" is
detected (the last, like in the original code, or the first, like in
patchShort.diff).

Comment 1 Adrian Nistor 2013-06-29 19:12:32 UTC

Created attachment 30500 [details]
patchShort

Comment 2 Violeta Georgieva 2013-07-01 10:37:25 UTC

(In reply to Adrian Nistor from comment #0)
> The above fix (in patch.diff) is certainly correct (it's easy to see
> through code inspection), but I think we can have an even shorter
> patch (one line, in patchShort.diff): just break as soon as "pos" is
> set, without reversion the loop order.  patchShort.diff is correct
> only if there can be only one "elements[i]" with class name
> "org.apache.catalina.core.ApplicationFilterChain" and method name
> "internalDoFilter" or if it doesn't matter which such "elements[i]" is
> detected (the last, like in the original code, or the first, like in
> patchShort.diff).

We need the last element and not the first one. So the first patch is the proper one.

Regards
Violeta

Comment 3 Violeta Georgieva 2013-07-01 11:25:36 UTC

Thanks for the report.
The first patch was applied in trunk and 7.0.x and will be included in 7.0.42 onwards.