Re: wresize and maxx/maxy short int overflow

[Thomas Dickey]

On Mon, 2 Nov 2009, Katarina Machalkova wrote:

> Hello, list,
>
> Following is the code snippet:
>
> {
>   WINDOW *w
>    ...
>    LOG << "One: " << w->_maxy << " " << w->_maxx << endl;
>    int ret = ::wresize( w, lines, columns );
>    LOG << "Two: " << w->_maxy << " " << w->_maxx << endl;
> }
>
> maxy/maxx are short ints (NCURSES_SIZE_T, to be more precise), while wresize()
> takes "normal" ints as params. Now I'm trying to make the window really big in
> Y dimension by setting 'lines' param to value greater than 32 768.

NCURSES_SIZE_T is a signed short just because of binary compatibility...

I can improve this specific case by returning an error if the parameters
go out of bounds (there are some others of course).

> The above prints:
> One: 3 22
> Two: -22207 22
>
> Is this bug in a sense that maxy (maxx respectively) should never become
> negative,  or is it responsibility of the application calling wresize to make
> sure its params are always in range of short ints and overflow of maxy/maxx
> never occurs?

generally the library "should" check its parameters.

(I recall some discussion - xorg is recent - from developers who
insist that libraries shouldn't do this ;-)

> Thanks for advice (it's likely PEBCAK what I'm seeing but I'd rather be sure)
>
> hB.
> --
>  \\\\\              Katarina Machalkova
>  \\\\\\\__o          YaST developer
> __\\\\\\\'/_          & hedgehog painter
>
>
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--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net