sendfile(): Invalid argument while installing

[spikeHollow]

I'm starting to try ocaml by going through their installation process. I'm stuck here.

Expected Behavior

opam installs dune correctly

Actual Behavior

on invoking

#=== ERROR while compiling dune.3.8.2 =========================================#
# context     2.1.5 | linux/x86_64 | ocaml.5.0.0 | https://opam.ocaml.org#509ab4d9
# path        ~/.opam/default/.opam-switch/build/dune.3.8.2
# command     ~/.opam/opam-init/hooks/sandbox.sh build ./_boot/dune.exe build dune.install --release --profile dune-bootstrap -j 7
# exit-code   1
# env-file    ~/.opam/log/dune-22736-950058.env
# output-file ~/.opam/log/dune-22736-950058.out
### output ###
# Error: sendfile(): Invalid argument
# -> required by _build/default/editor-integration/emacs/dune-flymake.el
# -> required by _build/install/default/share/emacs/site-lisp/dune-flymake.el
# -> required by _build/default/dune.install



<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
+- The following actions failed
| - build dune 3.8.2
+- 
- No changes have been performed

Reproduction

I'm using Linux mint. This is my first time installation. I invoked these commands according to the docs from Ocaml website.
bash -c "sh <(curl -fsSL https://raw.githubusercontent.com/ocaml/opam/master/shell/install.sh)"
opam init
opam install dune merlin ocaml-lsp-server odoc ocamlformat utop dune-release // here it gives error

[emillon]

Hi,
Thanks for the report.

The following pieces of information will be useful:

• can you try if it works with dune 3.7.1 (opam install dune.3.7.1). if it works, please also try 3.8.0 and 3.8.1
• is your HOME directory a network mount like NFS?
• can you install packages that do not use dune, for example you can try opam install fmt?
  Thanks

[emillon]

Can you also report which version of mint you are using, as well as your kernel version (uname -a)? thanks

[emillon]

I think what's happening is that in stdune/io, we detect that we're on linux, so we use the sendfile-based implementation, but the sendfile syscall returns EINVAL.

The manpage says:

Applications may wish to fall back to read(2) and write(2) in the case where sendfile() fails with EINVAL or ENOSYS.

So it's good to do that but I'm curious to see what's happening so that we can detect the situation more precisely.

[rgrinberg]

@emillon Do you want to send a fix for this?

So it's good to do that but I'm curious to see what's happening so that we can detect the situation more precisely.

It can happen under many circumstances so I wouldn't worry about it. However, one example might be doing sendfile from an NFS mount.

[emillon]

Yes. I added a test case in #8048. I was thinking of catching Unix_error here and calling copy_channels in the exception handler. Does that sound like a good fix?

[rgrinberg]

Yes, that's the right way to do it.

[emillon]

I added a fix which should be available in the next version of dune. In the meantime, versions of dune before 3.8.0 should work.