Re: Recursive invocation of variable_expand_string bug version 3.80

[Robert Schiele]

On Thu, Apr 01, 2004 at 11:49:42AM -0800, Jon Haswell wrote:
> The problem is in the routine variable_expand_string in how it handles
> access to variable_buffer. When the problem occurs it has been called to
> expand the $(eval $(call ... code above and it does this using the default
> variable_buffer size of 200. When this routine is called recursively to
> handle expanding the osbasic.d contents the variable_buffer has to be
> expanded as the contents of osbasic.d are over 200 bytes long. This is done
> by the call to realloc which moves variable_buffer. However when we return
> to the outer invocation of variable_expand_string it still has its local
> variable 'o', used as the next location in variable_buffer to use, set to
> the old location of variable_buffer before it was expanded/moved. This then
> leads to some crazy pointer arithmetic and the attempt to allocate some
> very big buffers and hence the error seen.
> 
> The somewhat obvious fix for this problem would be to make the return
> function from variable_buffer_output just an offset into the buffer rather
> than the absolute pointer into the buffer. However this routine is used so
> frequently and at times in other functions arithmetic is performed directly
> on variable_buffer that this does not appear to be a simple patch and some
> one more familiar with this code might be able to suggest a better
> solution.

This is fixed in CVS by putting the buffer pointer on the stack when entering
the eval function.  Either get the fix from there, or drop me a note, then I
will send you a patch for 3.80.

Robert

-- 
Robert Schiele                  Tel.: +49-621-181-2517
Dipl.-Wirtsch.informatiker      mailto:address@hidden

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