Re: [ft-devel] those OVERFLOW_* macros and Fontval b69 (Re: Freetype-devel Digest, Vol 149, Issue 5

[Alexei Podtelezhnikov]

On Jun 4, 2017, at 16:32, Werner LEMBERG <address@hidden> wrote:

>>> Yes and yes.  They are ugly, and I wonder whether I should drop the
>>> `OVERFLOW_' part of its names to get `SUB_LONG', `ADD_INT32', etc.
>> 
>> Please drop OVERFLOW.
> 
> OK.
> 
>> I see them as a red flag to rethink the code.
> 
> I disagree, at least partially, since...
> 
>> The add and sub overflows should not be happening on 32 bits because
>> we limit ourselves to 1Gb bitmaps aka 32768x32768.  Even at 1/256
>> pixel resolution there is plenty of space to avoid overflows.
> 
> this means that malformed fonts can
> create arbitrarily large values very easily.  Ditto for bytecode.
> Checking every addition, subtraction or multiplication for overflow is
> something I want to avoid,

Of course, I am only suggesting rejecting input with unreasonably large 
coordinates or metric values.