[mapserver-dev] Regarding to the issue: segfault on transparent layers with new renderers (#3834)

Tamas Szekeres szekerest at gmail.com
Sun Aug 24 09:27:19 PDT 2014

No comments so far.

I've prepared a fix to show what I've meant by storing the outputformat
instead of the renderer vtable in symbolObj.


Let me know if such change can be applied in master.

This change also contains a fix for the memory leaks caused by the embedded
scalebar and legend symbols which is necessary for making the refcount
approach to work properly.

We might also utilize MS_REFCNT macros for the outputformat refcount
handling too (which are not yet used), but that would involve further
changes to be made in further files.

Best regards,


2014-08-20 17:42 GMT+02:00 Tamas Szekeres <szekerest at gmail.com>:

> Hi Devs,
> Regarding to #3834 <https://github.com/mapserver/mapserver/issues/3834>,
> I can see several hacks in the code attempting to fix the issue, but it
> seems we are still running into the same issue by getting a crash in
> msFreeSymbol at the line:
> s->renderer->freeSymbol(s);
> We've already been discussing about implementing a symbol cache at the
> renderers (and eliminate the need of maintaining back references to the
> renderer at symbolObj), however that seems to require fair amount of coding
> and testing at the first sight.
> What if we change the renderer reference in symbolObj from
> rendererVTableObj to outputFormatObj (which contains the vtable)? Since the
> outputformat is reference counted we could make sure the outputformat (and
> the vtable) exists until the corresponding symbolObj is alive?
> Best regards,
> Tamas
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