Re: bglibs-1.022/str/alloc.c comment

On Tue, Jun 21, 2005 at 04:58:19PM +0200, Uffe Jakobsen wrote:
> bglibs-1.022/str/alloc.c (line 32-36) states:
> ---
> 32: int str_alloc(str* s, unsigned size, int copy)
> 33: {
> 34:   char* news;
> 35:   unsigned newsize;
> 36:  if ((newsize = size + 1) < size) return 0;
> ---
> 
> I wonder if line 36 should have been this instead or ???
> 
> 36:  if ((newsize = size + 1) < s->size) return 0;

This comparison is done to protect against additive overflow.  That is,
trying to allocate a string whose size would overflow an unsigned
integer will fail instead of producing bugs.

> Anyway with the above construct it doesn't seem possible to resize a string 
> to something less than the actual size. It that correct ?

The str library is set up to always grow, never shrink, yes.  The only
way to shrink would be to free the string (which resets the size
parameter) and then reallocate it.
-- 
Bruce Guenter <[email protected]> http://em.ca/~bruceg/ http://untroubled.org/
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