[Devel] Memory problem when freeing cache nodes...

[Stephen Perry]

Hi - apologies if this problem has been seen before, but I'm using the 
cache support in FreeType 2.1.8 and am hitting a problem freeing cache 
nodes.  I'm currently using the cache to hold faces, charmaps, glpyphs, 
and small bitmaps, but have changed the memory allocator to something 
that will start failing when the resource allocation exceeds a specified 
limit.  The result is that FTC_Cache_NewNode() ends up calling 
FTC_Manager_FlushN() with a count of 71 and the passed in FTC_Manager 
has num_nodes equal to 1, and nodes_list points to a single node with 
next and prev references to itself.  I assume that this is all as intended.

The problem is that the for loop in FTC_Manager_FlushN() stashes the 
previous pointer before calling ftc_node_destroy(), but doesn't check to 
see if it is the same node as the node that was actually destroyed. 
This results in us accessing freed data the next time around the loop.

I've worked around this problem (I am also seeing some other memory 
related problems that I'm currently looking into) by adding a 
"manager->nodes_list != NULL" check in the for loop condition, but 
didn't know if there was a better way, or if for some reason this case 
shouldn't be possible at all.

Any recommendations would be welcome...


Many thanks!


steve.


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