[haiku-development] What to do with termcap?
- From: Siarzhuk Zharski <zharik@xxxxxx>
- To: <haiku-development@xxxxxxxxxxxxx>
- Date: Wed, 30 Jan 2013 15:31:37 +0100
Dear Colleagues,
during the last week I was playing in my sandbox and going to reduce
the population of Terminal bugs. Those bugs that are related to various
control sequences parsing, colors rendering etc. And I have predictably
landed in our current termcap database that looks definitely outdated
nowadays and was hacked some times for our needs. Frankly speaking I
convinced that we must adjust our Terminal emulation functionality to
mimic declared terminal type as close to it's most used capabilities
set as possible. That is why I have looked for termcap update first.
During seeking for more actual versions of termcap I visited
"Termcap/Terminfo Resources Page" at http://www.catb.org/~esr/terminfo/
that looks like origin of our termcap database version too. This
resource pretends to be a "master" of termcap/terminfo databases. The
problem with termcap file provided on this page is that it is broken.
Both terminfo and termcap databases available on this page are generated
from so known master termtypes file. Generation of termcap database is
just compiling this file using "tic -C" command. This process has one
unpleasant "feature" - it comments out the capabilities that cannot be
converted from terminfo to termcap format safely. I suspect just because
of tic laziness.
On the good side the sanity check which performed by every
ncurses-based application can catch some logical problems in terminal
descriptions. Look into https://dev.haiku-os.org/ticket/1957 for results
of this check. But on the bad side a lot of commented-out capabilities
cannot be catch. And we have such broken termcap database - some of
"un-paired" capabilities were hacked during fixing #1957 but there are
still about 1100 commented out capabilities - so corresponding terminal
entries cannot be called valid.
The only actual source of terminal capabilities information I have
found, is the terminfo.src file provided with ncurses sources
distribution. This file was derived from the termtypes.master published
years ago at mentioned above "Termcap/Terminfo Resources Page".
Obviously it can be converted into termcap using tic compiler, but the
result is unacceptable because of many commented out capabilities. But
anyway I think it is a good idea to keep our termcap database
synchronized with the version provided by ncurses.
So the first opportunity to bring termcap in order is just to use
manually corrected database generated from the ncurses'
termtypes.master. Another one - switch to using terminfo. As far as I
have shortly seen, ncurses can supersede the libtermcap functionality
completely. But in this case the sweet dream about ncurses outsourcing
become more remote than before - there are about dozen tools in the
Haiku sources linking to libtermcap. But, AFAIR, FreeBSD is not
"ashamed" about having ncurses in theirs system source tree. ;-)
Please share your opinions. Thank you for patiense!
--
Kind Regards,
S.Zharski
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