Date: Tue, 6 Apr 2021 12:17:33 -0600 (MDT)
From: Ariadne Conill <ariadne@dereferenced.org>
To: ~alpine/devel@lists.alpinelinux.org
Subject: [3.15] System change proposal: Use netbsd-curses instead of GNU
 ncurses
Message-ID: <e12847f2-4cea-c3e8-84c3-e98b92553f8e@dereferenced.org>
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Hello,

This proposal is largely centered around normalizing our package set with 
other musl distributions, such as Sabotage and Adelie, which already ship 
netbsd-curses in favor of GNU ncurses.

## GNU ncurses vs netbsd-curses

* GNU ncurses is presently the standard curses library on Linux systems.

Some applications may access private mechanisms inside the curses 
implementation and need patching.

* Both libraries implement the POSIX curses API.

This means, 99% of applications won't need patching and should be 
basically compatible.

* ncurses ships a huge terminfo database.

Ncurses presently ships a database which takes 7MiB on disk.  We split 
this into `ncurses-terminfo` and `ncurses-terminfo-base` to reduce the 
installed size to only 216KiB by default.

netbsd-curses precompiles the terminfo database into a small CDB format 
database.

* ncurses is large.

At present, we try to avoid using curses support in programs which 
optionally use it, because ncurses is a heavy dependency (ncurses-libs is 
500KiB, plus the 216KiB base terminfo database, plus 284KiB for tools). 
netbsd-curses is only 1.3MiB on disk for everything and can be split in 
the same way to reduce size.

* GNU ncurses code quality is lacking.

GNU ncurses is littered with macros and other layers of preprocessing. 
This makes it hard to understand the source code, which makes hotfixing 
security vulnerabilities a potential challenge.

netbsd-curses is written in straightforward C89/C99, one of the preferred 
languages for tools and base system components in Alpine.  It is much 
easier to hack on than GNU ncurses.

Simpler code also makes for more portable code in general.

## Benefits to Alpine

Alpine benefits from switching to a curses implementation that is 
actively developed on musl systems, in addition to the other benefits 
outlined above.

## Contingency Plan

We will do an experimental rebuild with netbsd-curses-dev providing 
ncurses-dev.  If this goes well, then we will switch to netbsd-curses.

If there is a problem, then we will try to fix netbsd-curses first, 
failing that, we will revert back to GNU ncurses.

Ariadne