[PR PATCH] [RFC] screen: don't enable multiuser mode by default.

[PR PATCH] [RFC] screen: don't enable multiuser mode by default.

[ericonr]

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There is a new pull request by ericonr against master on the void-packages repository

https://github.com/ericonr/void-packages screen
https://github.com/void-linux/void-packages/pull/30241

[RFC] screen: don't enable multiuser mode by default.
This requires that the screen binary be suid.

<!-- Mark items with [x] where applicable -->

#### General
- [ ] This is a new package and it conforms to the [quality requirements](https://github.com/void-linux/void-packages/blob/master/Manual.md#quality-requirements)

#### Have the results of the proposed changes been tested?
- [ ] I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me
- [ ] I generally don't use the affected packages but briefly tested this PR

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A patch file from https://github.com/void-linux/void-packages/pull/30241.patch is attached

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From 341e44c40f798d985135319e46f8a14b35a45bd8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89rico=20Nogueira?= <erico.erc@gmail.com>
Date: Wed, 14 Apr 2021 17:17:30 -0300
Subject: [PATCH] screen: don't enable multiuser mode by default.

This requires that the screen binary be suid.
---
 srcpkgs/screen/template | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/srcpkgs/screen/template b/srcpkgs/screen/template
index 613696d9f373..4fcf97e83e91 100644
--- a/srcpkgs/screen/template
+++ b/srcpkgs/screen/template
@@ -1,7 +1,7 @@
 # Template file for 'screen'
 pkgname=screen
 version=4.8.0
-revision=2
+revision=3
 build_style=gnu-configure
 configure_args="--with-sys-screenrc=/etc/screenrc --enable-pam
  --enable-colors256 --enable-rxvt_osc --enable-telnet
@@ -15,10 +15,14 @@ homepage="http://www.gnu.org/s/screen/"
 distfiles="${GNU_SITE}/$pkgname/$pkgname-$version.tar.gz"
 checksum=6e11b13d8489925fde25dfb0935bf6ed71f9eb47eff233a181e078fde5655aa1
 
+build_options="multiuser"
+
 post_install() {
 	vinstall etc/etcscreenrc 0644 etc screenrc
 	vinstall etc/screenrc 0644 etc/skel .screenrc
 	vinstall ${FILESDIR}/screen 0644 etc/pam.d
 
-	chmod 4755 ${DESTDIR}/usr/bin/screen-${version}
+	if [ "$build_option_multiuser" ]; then
+		chmod 4755 ${DESTDIR}/usr/bin/screen-${version}
+	fi
 }

Re: [PR PATCH] [Merged]: [RFC] screen: don't enable multiuser mode by default.

[ericonr]

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There's a merged pull request on the void-packages repository

[RFC] screen: don't enable multiuser mode by default.
https://github.com/void-linux/void-packages/pull/30241

Description:
This requires that the screen binary be suid.

<!-- Mark items with [x] where applicable -->

#### General
- [ ] This is a new package and it conforms to the [quality requirements](https://github.com/void-linux/void-packages/blob/master/Manual.md#quality-requirements)

#### Have the results of the proposed changes been tested?
- [ ] I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me
- [ ] I generally don't use the affected packages but briefly tested this PR

<!--
If GitHub CI cannot be used to validate the build result (for example, if the
build is likely to take several hours), make sure to
[skip CI](https://github.com/void-linux/void-packages/blob/master/CONTRIBUTING.md#continuous-integration).
When skipping CI, uncomment and fill out the following section.
Note: for builds that are likely to complete in less than 2 hours, it is not
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<!-- 
#### Does it build and run successfully? 
(Please choose at least one native build and, if supported, at least one cross build. More are better.)
- [ ] I built this PR locally for my native architecture, (ARCH-LIBC)
- [ ] I built this PR locally for these architectures (if supported. mark crossbuilds):
  - [ ] aarch64-musl
  - [ ] armv7l
  - [ ] armv6l-musl
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Re: [RFC] screen: don't enable multiuser mode by default.

[tornaria]

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New comment by tornaria on void-packages repository

https://github.com/void-linux/void-packages/pull/30241#issuecomment-885774338

Comment:
This actually prevents screen from running at all:
```
$ screen
Cannot make directory '/run/screens': Permission denied
```

Ideas:
- Maybe some init script should `mkdir -m 1777 /run/screens` at startup?
- Maybe removing `--with-socket-dir=/run/screens` would use an alternative default which works for all users?

Re: [RFC] screen: don't enable multiuser mode by default.

[ericonr]

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New comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/30241#issuecomment-885782222

Comment:
Damnit, I only tested when the directory already existed :/

Re: [RFC] screen: don't enable multiuser mode by default.

[ericonr]

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New comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/30241#issuecomment-885787475

Comment:
> Maybe removing --with-socket-dir=/run/screens would use an alternative default which works for all users?

Would be nice but breaks existing sessions unless the person sets SCREENDIR. I think that's worse...

> Maybe some init script should mkdir -m 1777 /run/screens at startup?

Good enough, IMO.

Re: [RFC] screen: don't enable multiuser mode by default.

[tornaria]

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New comment by tornaria on void-packages repository

https://github.com/void-linux/void-packages/pull/30241#issuecomment-885791498

Comment:
I also like the `mkdir` choice better, because it allows one to easily reenable multiuser screen by just making the binary setuid.

Note that since `/run` is cleaned at reboots (or a tmpfs) the directory has to be created at every boot, not at install time.

Re: [RFC] screen: don't enable multiuser mode by default.

[ericonr]

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New comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/30241#issuecomment-885791878

Comment:
I am opening a PR in a bit. Initially I went with removing socket-dir, but realized the potential for breakage.

Re: [RFC] screen: don't enable multiuser mode by default.

[ericonr]

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New comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/30241#issuecomment-885793596

Comment:
@tornaria https://github.com/void-linux/void-packages/pull/32159