Re: [screen-devel] suspicious code in encoding.c

[Carl Drougge]

On Fri, Feb 18, 2022 at 02:15:05 +0100, Vincent Lefevre wrote:

> Indeed, the code is really strange:
> 
>   (c & 0x3000000) >> 12 ^ 0xf8
> 
> will be stored in a char. So why dealing with bits more significant
> than the 8 bits of a char?

I too recently noticed this. I have now made a nice clean patch and
submitted that as a new bug: https://savannah.gnu.org/bugs/?62097

> The master branch has a similar code, but with int replaced by
> uint32_t, so that the warning disappears just because of the unsigned
> type (the behavior becomes fully specified by the C standard instead
> of being implementation defined).

The master branch looked ok-ish to me, the actualy problem code wasn't
there, just the incorrect mask for 4 byte sequences (which does no harm if
the value is in range).

I would be happy to replace these functions with something easier to read
if there is interest.