[gentoo-dev] Resolve build time default editor dependency. (was: How get ebuild provider virtual/category.)

[Peter Volkov (pva)]

Hello.

Anatoly raised really important concern and currently I've started to
think about fix. One possible solution requires virtual/editor to suite
glep 37 and thus affects many packages. So... wondering why this change
was not done I'd like to discuss the problem on the list.

Problem:
There are programs (fcrontab, visudo, vipw and etc.) which require
default editor to work. To select editor they use these two steps:
1.) take editor name from environment (EDITOR or VISUAL vars)
2.) if there is not editor use defined at build time compiled in default

The problem is that both of methods suck in some special situations
which, of course, happen in Gentoo with its extreme configurability.
Currently it is impossible to specify build time dependency reliably for
virtual/editor: most of packages either use nano or vi (either
trough ./configure option or #define in sources) but in the system
without nano or vi this package either not emerges [1,2] or fails to
work[3,4] (yes... if EDITOR is not set). But EDITOR *is not* set when
program is started from sudo because sudo for security reasons drops
environment (are there any other cases when environment is dropped?).

Well. One possible answer that this is not a problem: build time
dependencies are weird, always set EDITOR and never run such programs
from sudo because this allows to do everything with the system. But I'd
like to point at two points: firstly, some users use sudo just to avoid
logging in as root and, secondly, upstream consider compiled in defaults
to work. Thus IMO this is a problem.

The possible solution is to add virtual/editor ebuild which will besides
enumerating all virtual providers install /usr/bin/editor program. This
will be a simple wrapper (bash) script which will use EDITOR environment
variable to start editor, in case environment variable does not exist
use EDITOR from /etc/rc.conf and as the last resolve just issue error
message identifying possible ways to setup editor. All programs that use
compiled in default editor should use this wrapper script. This will
solve ambiguity of build time dependency and allow to use sudo reliably.

While I continue playing in my overlay I'd like to know if there are any
problems with this solution? Currently this change seems to satisfy KISS
concept and fix some problems... thus should be implemented. I'll wait
for some time and open two trackers one for virtual/editor providers
another for virtual/editor build time dependency users and then add
virtual/editor ebuild, remove PROVIDErs and continue working on packages
that use compiled in editor defaults.

References:
[1] https://bugs.gentoo.org/show_bug.cgi?id=124904
[2] https://bugs.gentoo.org/show_bug.cgi?id=94771
[3] https://bugs.gentoo.org/show_bug.cgi?id=149376
[4] https://bugs.gentoo.org/show_bug.cgi?id=149339

Thank you for your time,
Peter.