[geos-devel] [Buffer] Assertion failure causes crash in RightmostEdgeFinder::findEdge()

[Stephen Wong]

Hello,

I have been using the geos library for buffer functions and found a crash
case.  When I stepped into the code, I found that
RightmostEdgeFinder::findEdge() crashes when no forward DirectedEdge is
input into the function.  The function crashes because of a null pointer
reference error (minDe=0x0) later in the code.  The assertion failure that
catches this is on line 77:

assert(checked>0);


Is this case supposed to be possible?  I also found that
BufferSubgraph::create()
calls findEdge(), and a comment in the code says that "We are assuming that
dirEdgeList contains *at least* ONE forward DirectedEdge".  Again, what
happens if the DirectedEdge list does not?  I don't think it should crash...

Thanks,

Stephen
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