Re: PATCH 1/2: Make gotoxy & siblings use unsigned variables

[Edgar Toernig]

Nigel Cunningham wrote:
>
> Andries Brouwer wrote:
>
> > When did you last see a console in text mode with a line length
> > of more than 2^31 ?
> >
> > If you go for a minimal patch then you should replace "char"
> > in one or two places by "unsigned char" and that is all.
>
> Of course you're right about 2^31 columns, but the rest of the code used
> unsigned ints as well, not because it expects 2^31 columns, but because
> (if I understand the code right), the numbers can be part of escape
> sequences... I'm looking at csi_m in vt.c.

Yes, they may be part of escape sequences and that's why your patch is
wrong.  See the comment above gotoxy:

    /*
     * gotoxy() must verify all boundaries, because the arguments
     * might also be negative. If the given position is out of
     * bounds, the cursor is placed at the nearest margin.
    */

If you make the arguments unsigned it will choose the wrong
margin for negative values.  That will i.e. happen if you send
the sequence to move the cursor 10 spaces left when it is only
in column 5.

Afaics, the only thing that needs fixing is putconsxy:

 void putconsxy(int currcons, char *p)
 {
-        gotoxy(currcons, p[0], p[1]);
+        gotoxy(currcons, (unsigned char)p[0], (unsigned char)p[1]);
         set_cursor(currcons);
 }

Ciao, ET.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/