Re: Providing an alternative TERMINFO environment variable

[Thomas Dickey]

On Fri, Dec 01, 2023 at 05:37:53PM -0600, G. Branden Robinson wrote:
> At 2023-11-29T14:50:39-0500, Thomas Dickey wrote:
> > ----- Original Message -----
> > | From: "G. Branden Robinson" <g.branden.robinson@gmail.com>
> > | At 2023-11-28T17:14:26+0000, Igor Todorovski wrote:
> > |> I have added the below code to enable setting ASCII_TERMINFO. I’m
> > not |> sure if the environment variable name is reasonable or not, but
> > the |> z/OS system default checks for TERMINFO so I needed a way to
> > tell |> ncurses where to pick up tis terminfo db.
> > |> 
> > |> Is there a better alternative?
> > | 
> > | Doesn't TERMINFO_DIRS do this job?
> > 
> > No - $TERMINFO is tested first, and if he has some other
> > implementation where he is setting $TERMINFO, there's a conflict.
> 
> I see now.  Why not make Igor's proposed environment variable
> "TERMINFOPATH", since it would then have semantics like other *PATH
> variables (being an override), and _not_ make it conditional on a z/OS
> symbol, but applicable everywhere?

But it's not a general problem.  If I provide it "everywhere", it's
certain that others using ncurses terminfo will provide conflicting
implementations, resulting in a nuisance.

See the earlier discussion here -

https://lists.gnu.org/archive/html/bug-ncurses/2023-02/msg00008.html

ncurses checks that the compiled terminfo follows some formatting rules,
but assumes that the strings stored in the terminfo database do not need
translation.  Apparently zOS is storing strings in EBCDIC and later
(in tput?) converting to ASCII.

If I had more information on what the zOS terminal database contents
were, I'd prefer to do a sanity check on it to ensure that it's not
returning data that was translated to EBCDIC.

https://www.ibm.com/docs/en/iis/11.7?topic=tables-ascii-ebcdic

For instance, checking the cursor_address capability, which often
begins \E[, I'd expect something like this:

                ASCII   EBCDIC
        \E      0x1b    0x27    "'"
        [       0x5b    0x4a    "J"

There are other two-character prefixes, but that's an example of something
that I could do to ignore the unwanted data -- on zOS.

-- 
Thomas E. Dickey <dickey@invisible-island.net>
https://invisible-island.net

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