[MapServer-dev] Zero-size SVG rendering : mapserv.fcgi crashes

[Philippe Ghesquiere]

Hi all,

My mapserver installation is based on :

   - Mapserver 7.6.3
   - MapCache : 1.12.0

I bumped into a configuration (zoom, orientation, ...) where an SVG symbol
has one null dimension (height or width).
The rendering process crashes with the following error message (mapcairo.c
<https://github.com/MapServer/MapServer/blob/rel-7-6-3/mapcairo.c>) :
mapserv.fcgi: /builds/i4d/datacenter/mapserver/MapServer/mapcairo.c:1074:
msRenderRasterizedSVGSymbol: Assertion `svg_cache->pixmap_buffer->height &&
svg_cache->pixmap_buffer->width' failed.

The code snippet  shows :
//already rendered at the right size and scale? return
if(svg_cache->scale != style->scale || svg_cache->rotation !=
style->rotation) {
...
}
assert(svg_cache->pixmap_buffer->height && svg_cache->pixmap_buffer->width);

Instead of crashing the rendering process, wouldn't it be more appropriate
to test buffer dimensions beforehands.
Something like :
if ( (svg_cache->pixmap_buffer->height == 0 ||
(svg_cache->pixmap_buffer->width == 0) )
   return MS_FAILURE;

//already rendered at the right size and scale? return
if(svg_cache->scale != style->scale || svg_cache->rotation !=
style->rotation) {
...
}

Philippe
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