Re: [ft-devel] Outline n_points are int16 so overflow is possible because missing check

[John Tytgat]

address@hidden wrote:
> [...]
> BTW, the path construction of Adobe PostScript language
> restricts the number of points to 1500 (so, PS Type3 font
> has this limitation). It's far smaller than font description
> languages in above.
That's not true (anymore) for a long time (decade ?).  You can have 
paths with much more points in Adobe's PostScript 3 implementation and I 
assume Ghostscript as well.  But that's not relevant for your FT 
observation.
> [...]
> I've checked the Embedded Linux Kernel System (ELKS,
> 16-bit kernel based on Linux) by Bruce's C compiler (bcc),
>
>         (int) ( (short) 0x7FFF + (short) 0x7FFF ) < 0x7FFF
>
> is true. On 32-bit Linux kernel with gcc, it is false.
> Therfore, a cast to larger type before summation is
> required. How do you think of following patch?
>   
Note that signed integer overflow is *not* defined in C, so this is 
compiler (setting) depending.  gcc uses this liberty to make the best 
choice for optimisation and code generation.  unsigned integer overflow 
is defined (as wrapping around).

John.