Re: Fix, NSLayoutManager

[Fred Kiefer]

Georg Fleischmann wrote:
> Hi,
>
> here is a little patch for the NSLayoutManager fixing a problem with  
> layout_char. layout_char is unsigned but may become "negative", thus flipping  
> over to huge positive. The huge positive value then is not sattisfying the '<'  
> comparison.
>
> Georg
>
>
> 2004-03-10  Georg Fleischmann
>         * gui/Source/NSLayoutManager.m [NSLayoutManager textStorage:...]:
>           keep (unsigned) layout_char in legal range, in case it becomes < 0
>
>
>
> *** gui/Source/NSLayoutManager.m.old    2004-02-15 19:23:13.000000000 +0100
> --- gui/Source/NSLayoutManager.m        2004-03-10 19:30:38.000000000 +0100
> ***************
> *** 1800,1806 ****
>     if (layout_char > r.location)
>       {
>         layout_char += lengthChange;
> !       if (layout_char < r.location)
>           layout_char = r.location;
>       }
>
> --- 1800,1806 ----
>     if (layout_char > r.location)
>       {
>         layout_char += lengthChange;
> !       if (layout_char < r.location || layout_char > r.location + r.length)
>           layout_char = r.location;
>       }
>   

I think you did spot a real problem here, but your solution just doesn't 
look right. An unsigned number never should be allowed to wrap around. 
What about a check like this:

    if (layout_char > r.location)
      {
        if (layout_char + lengthChange < r.location)
          {
            layout_char = r.location;
          }
        else
          {
            layout_char += lengthChange;
          }
      }