Comparison with False - something I don't understand

[Paul Rubin]

Tim Harig <usernet at ilthio.net> writes:
> I am not talking about what setjmp() has to do, I am talking about what
> *you* have to do after setjmp() returns.  If you have allocated memory in
> intermediate functions and you don't have a reference to them outside of
> the functions that longjmp() bypasses from returning properly (and thus
> either not clearning data structures or returning a reference to those data
> structures as it normally would) then you have potential memory leaks,
> dangling pointers, etc.

Sure, that's what the aux stack is for--you put any such references into
it, for the setjmp handler to find later.  You do that BEFORE setjmp
returns, of course.

> I am not saying that this cannot be done.  What I am saying is that it
> is inherently error prone.

I suppose so, but so is everything else in C.  On the overall scale of
C-related hazards, this particular one isn't so bad if you code in a
consistent style and are disciplined about recording the cleanups.

You could also use something like an obstack, which is a stack allocated
on the heap, so it persists after the control stack returns, but you can
release the whole thing in one operation.