[postgis-devel] - early return from force_collection...DONT!

[dblasby at openplans.org]

strk,

I saw the comment "- early return from force_collection" in your message
and checked the function.

*NEVER* just return a pointer argument given to a function!  Always copy
and return.

Your implementation may fail if the incomming geometry isnt actually
toasted (detoasting makes a "copy" of the data for you).  If its not
toasted (ie. < 2kb) then you are relying on postgresql's memory manager
to "do the right thing" and not free the arguments until *after* its
serialized the result (since they're the same block of memory).  Thats
a pretty big assumption!!

The function may also be called by other people's functions (using the
direct function call method) or inside a chain of functions by
postgresql, or in a chain of calls involving non-cachable functions. 
All of these have assumptions about whats being returned and what they
can do with it.

dave


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