mgserver crash in rare occasions

[andymorf]

investigations due to daily crashes of our production server led to following results:

After Exception in error.log

 Error: Failed to stylize layer: RP_ZO_Zonen_rk_OP
        Problem:\nThe application encountered a problem and could not finish the operation you just requested properly.\n\nSolution:\nIf it\'s the first time you met this problem, try again or restart the application / session; otherwise, describe the steps to reproduce this problem to the server administrator for suggestions.
 StackTrace:
  - MgMappingUtil.StylizeLayers() line 918 file D:\development\MgDev_trunk\Server\src\Services\Mapping\MappingUtil.cpp

it was a matter of time mgserver passed away or freezed. Crash could be reproduced in a debugging session and problem was narrowed to line 1806 in AGGRenderer.cpp where

unsigned width was assigned 0 which resulted in an access violation in function "copy_hline" on 1808: there "--len"(=width) provides a first value of 4G in the while clause.

One of my "deadly" GETDYNAMICMAPOVERLAYIMAGE/feature combination led to following assignments in AGGRenderer::SetPolyClip:

minx=1022.258, miny=618.259
maxx=1022.378, maxy=792.378
iminx=1021, iminy=617
imaxx=1020, imaxy=790
-> width=0
-> ...crash

[jng]

Would it be possible for you to isolate the offending feature(s) and attach a sample data file with these offending features (scrub out whatever sensitive feature attributes if required)?

[jng]

It appears based on the stack trace, you're able to build MapGuide trunk yourself. Can you try the attached patch and see if it fixes your issue?

[jng]

I built a copy of MgRenderers.dll where the width variable was hardcoded to 0 just to try and trigger this access violation. It never happened.

We really need a sample data set that demonstrates this crash.

[jng]

Closing as duplicate of #2736, which sounds very similar to the issue described here