cvs: use ssh instead of rsh.

[joshuakb2]

If no ssh executable can be found during the configure phase, CVS defaults to using rsh for remote connections instead. This seems undesirable in 2024.

Things done

• Added the openssh package to the build inputs so that the ssh executable is found by configure.

• Built on platform(s)

  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin

• Tested, as applicable:

  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages

• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage

• Tested basic functionality of all binary files (usually in ./result/bin/)

• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)

  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module

• Fits CONTRIBUTING.md.

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[AndersonTorres]

buildInputs?

[joshuakb2]

buildInputs?

Yes, it seems that if configure doesn't find an ssh executable in $PATH during the build, the built cvs executable won't even try to use ssh even though that's the intended behavior according to the release notes, and it's the behavior on every other Linux distro I've used.

However, it occurs to me now that maybe configure can't tell the difference between a real ssh executable and a fake ssh executable that exists only during the configuration step. The cvs executable seems to run whatever ssh is in the environment at runtime anyway. So maybe there's no need to depend on the real openssh package to fix this.

[joshuakb2]

Sure enough, it works fine with a fake SSH executable present during the build. So I think I'll amend my pull request to not use the openssh package, it's unnecessary.

[AndersonTorres]

Let me ask:

If I built CVS before your PR, and install both CVS and OpenSSH, then CVS will be unable to find SSH.
Is this correct?

[joshuakb2]

Yes, exactly. In that case it executes rsh instead, so it never finds ssh because it isn't even attempting to find it.

…

On Wed, Oct 9, 2024, 3:14 PM Anderson Torres ***@***.***> wrote: Let me ask: If I built CVS before your PR, and install both CVS and OpenSSH, then CVS will be unable to find SSH. Is this correct? — Reply to this email directly, view it on GitHub <#347374 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADUECYWN6IN5TXXO5SBHMKLZ2WMDZAVCNFSM6AAAAABPTMGYDSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDIMBTGQ2DANJVHE> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[AndersonTorres]

From what I have understood by reading the source code,

• there is a configure flag, --with-ssh=<executable> that hard-codes the SSH path
• at runtime CVS reads $CVS_SSH when set
• the :extssh: method will use $CVS_SSH if set, or fall back on ssh

It looks like it's possible to use ssh under cvs.

[joshuakb2]

I believe I was able to get the existing build of cvs from nixpkgs to use SSH by setting CVS_RSH=ssh in my environment at runtime. Before creating this pull request, I tried each of the 3 methods you suggested and none of them worked. Just because it's possible to make it work doesn't mean it makes sense to require an extra environment variable be defined just so that cvs will behave the way its own authors describe. I've just migrated my work computer from Ubuntu to NixOS. Ubuntu's cvs package does not attempt to use rsh.

[AndersonTorres]

Just because it's possible to make it work doesn't mean it makes sense to require an extra environment variable be defined just so that cvs will behave the way its own authors describe.

There are tutorials on the Internet suggesting to set environment variables in order to use CVS:
https://alvinalexander.com/blog/post/cvs/login-cvs-server-using-ssh/

And this is supported by the documentation:
https://www.gnu.org/software/trans-coord/manual/cvs/html_node/Connecting-via-rsh.html

I've just migrated my work computer from Ubuntu to NixOS. Ubuntu's cvs package does not attempt to use rsh.

Nice.
Can I have a look at the build scripts Ubuntu uses to build CVS, so that I can adapt them to Nixpkgs?

[joshuakb2]

I'm not interested in trying to convince you that this is a worthwhile change. I find it valuable, personally. I was somewhat annoyed when I discovered that cvs doesn't work the same way in NixOS as it works on Ubuntu because it meant that I couldn't get work done until I found a workaround. I thought the community may benefit from this change.

Nice.
Can I have a look at the build scripts Ubuntu uses to build CVS, so that I can adapt them to Nixpkgs?

Be my guest, I've never looked at them personally. I've just used cvs on other systems.