tcsh subshell escaping broken

[Anatoly Borodin]

Release: Ubuntu 17.04 Zesty
tcsh version: 6.20.00-7

I’m trying to fix the integration between mc and the recent version of
tcsh (as a subshell) that got broken in Ubuntu 17.04 Zesty. I have
noticed that the escaping has been changed in the commit
https://github.com/tcsh-org/tcsh/commit/c445a078a7b124fd86dd6eba9c076476b8e757d4,
that can be tested with

mkdir -p '/tmp/a b' && ls -d "`printf "%b" '\0057tmp\0057a\0040b'`"

Before the commit:

/tmp/a b

(The same result in bash and zsh btw.)

After the commit:

ls: cannot access '/tmp/a': No such file or directory
ls: cannot access 'b': No such file or directory

Looks like a regression in the version 6.20.

[Anatoly Borodin (anatoly.borodin)]

I'm also trying to contact the upstream commit author Christos Zoulas, but he seems to be busy.

The website http://tcsh.org/ is down right now.

[Anatoly Borodin (anatoly.borodin)]

I'm sorry, actually the Christos have naswered my email, but it got into the spam folder. Let's see if we can get an upstream solution.

[Anatoly Borodin (anatoly.borodin)]

Christos explained that tcsh escaping is tricky, buggy, and "fixing" it in a proper way can break legacy scripts.

I propose to fix the problem on the Midnight Commander side instead. To prevent messages like 'Warning: Cannot change to /tmp/a b/c d..' and failure to cd to such directories when using mc with recent versions of tcsh (SHELL=/bin/tcsh), mc can be patched (src/subshell/common.c) the following way: %b should not be escaped (or escaped with single quotes), because there are no ambiguities. See the attached diff for an example. I've tested the patch with different shells: tcsh (both old and new), bash, zsh, fish.

I also propose pushing this patch to the upstream (https://github.com/MidnightCommander/mc), and I will contact the dev team correspondingly.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "mc.diff" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

[Anatoly Borodin (anatoly.borodin)]

The issue has been fixed in https://github.com/MidnightCommander/mc/commit/0fec3ef449de6f22281161ba7af8f5dbb948292d , and is to appear in the next mc release (4.20).

[dino99 (9d9)]

That version is now dead
http://news.softpedia.com/news/ubuntu-17-04-zesty-zapus-has-reached-end-of-life-upgrade-to-ubuntu-17-10-now-519360.shtml

[Anatoly Borodin (anatoly.borodin)]

dino99, why should this bug be marked as Invalid? The newer releases (Artful and Beaver-dev) are still (as of today) have the older version (3:4.8.19-1) of Midnight Commander without the patch (upstream release 4.8.20 of 25.11.2017). The newer releases just weren't released in July 2017.

PS I don't know about the plans of the MC packege maintainers at Debian. Is MC going to be updated in Beaver? Is it possible to port just the patch (it's trivial) to the Ubuntu package 3:4.8.19?

[dino99 (9d9)]

Request for archive upgrade:

https://midnight-commander.org/ (both Debian & Ubuntu still have 4.8.19)
' ppa:o9000/zulu ' (4.8.20) ' ppa:simonarons/ppa ' (4.8.20 +lbzip2)

Server down : https://github.com/tcsh-org/tcsh

[Anatoly Borodin (anatoly.borodin)]

Thanks dino99!

Are any actions from me required?

[dino99 (9d9)]

Debian maintainer is now Thomas Lange; Seems Christos is now away from that project.
https://salsa.debian.org/debian/tcsh

Googling around tcsh lets me thinking tcsh is less used nowadays, replaced by bash and else.
But if you have suggestions, maybe Thomas could accept them.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.