fdLock invalid argument error on WSL Ubuntu Bionic

[ygale]

Describe the bug

On Ubuntu Bionic running under WSL on Windows 10, after installing cabal-install-3.2 from the hvr PPA:

Every cabal command fails with the following error:

fdLock: invalid argument (Invalid argument)

To Reproduce

Run cabal init, or cabal update or any other cabal command except cabal --version.

I deleted the entire ~/.cabal directory and ran cabal update. Same issue.

System information

• Operating system: Ubuntu 18.04 (bionic), on WSL 1, on Windows 10
• cabal versions:
  cabal-install version 3.2.0.0
  compiled using version 3.2.0.0 of the Cabal library
• ghc version: 8.8.2

[ygale]

Looks like cabal is trying to use fcntl(F_SETLK) or similar for locking, via the lukko library. That won't work on WSL 1, see microsoft/WSL#1927.

It seems clear that Microsoft will not fix this. They are focusing on WSL 2, which won't be generally released for at least a few more months.

Is there any way to teach cabal not to use that kind of locking on this platform? Perhaps a flag that lets you override autodetection of what kind of locking to use?

[phadej]

Disable `ofd-locking` flag of lukko:

Enable open file descriptor locking. Available on Linux (kernel 3.15, released Jun 8, 2014).

Then `flock` looks will be used. I don’t know how well they are supported, though.

…

On 20. Feb 2020, at 19.26, ygale ***@***.***> wrote:  Looks like cabal is trying to use fcntl(F_SETLK) or similar for locking, via the lukko library. That won't work on WSL 1, see microsoft/WSL#1927. It seems clear that Microsoft will not fix this. They are focusing on WSL 2, which won't be generally released for at least a few more months. Is there any way to teach cabal not to use that kind of locking on this platform? Perhaps a flag that let's you override autodetection of what kind of locking to use? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or unsubscribe.

[ygale]

Thanks @phadej . I'll give it a try.

[phadej]

@ygale any updates?

[phadej]

Closing this. Turning off ofd-locking might or might not work, but there's nothing to do in Cabal or lukko.

[sheaf]

To confirm that @phadej's fix works: I added

constraints:
  lukko -ofd-locking

to cabal-install's cabal.project file when building cabal-install. This solved the issue, which I was running into on an Alpine Linux WSL2 distribution.

[sir4ur0n]

For what it's worth: I had exactly this issue on my WSL 1 system, while building almost any project with Cabal. I just upgraded today to Windows 2004 and WSL 2, and now it seems to work.

In case anybody else wonders if WSL 2 does solve this problem 😄

[July541]

I met the same problem and have no solution yet:(

[July541]

I met the same problem and have no solution yet:(

It works after I updated wsl1 to wsl2 :)

[cn-ml]

For what it's worth: I had exactly this issue on my WSL 1 system, while building almost any project with Cabal. I just upgraded today to Windows 2004 and WSL 2, and now it seems to work.

Thank you, this seems to fix the issue for me. I was running Ubuntu-18.04 on WSL 1. To upgrade it I first got the name of the image:

wsl -l -v

which showed me Ubuntu-18.04 Running 2 and then i ran

wsl --set-version Ubuntu-18.04 2

That took some time, but after that I restarted the Ubuntu shell and everything worked fine. Thank you for the solution, that saved me some time 👍

[Mikolaj]

@leftaroundabout: How to reproduce your findings?

[leftaroundabout]

Fresh Debian i386 install, fresh GHC-8.6.5, Cabal HEAD version (5b4258), after running the bootstrap.py following the instructions the resulting cabal executable has the fdLock invalid argument problem discussed here. Nuking the cabal clone, re-cloning, adding the lukko constraints in cabal.project.bootstrap and again bootstrapping did not make any difference.

Ok, I think I got it: the cabal.project.bootstrap isn't actually what matters to the bootstrap (?) and the flag instead needs to be set in bootstrap/linux-8.6.5.json. After changing

      ...
      "package": "lukko"
      ...
      "flags": [
        "+ofd-locking"
      ]

to

      "flags": [
        "-ofd-locking"
      ]

in the JSON file, the fdLock issue is gone.

[Mikolaj]

Congratulations! Indeed bootstrap/README.md confirms this project file is used to create bootstrap data for new architectures and that's how it's used in the Makefile.