Shipping the interpreter

[straight-shoota]

I figure that should be fine. We just need an implementation of dlopen. But either of them will also require a dynamic loader (ld.so) available to be able to actually load shared libraries. That’s probably the most challenging problem because a statically linked binary misses that.
And that works I suppose there might then appear issues with libraries that are statically linked into the compiler and dynamically loaded by the interpreted program.

[skinnyjames]

@straight-shoota

The main problem is with a single library, libdl. The interpreter needs that in order to load dynamic libraries at runtime. Usually, this library is included in libc. That’s also the case with musl libc, however it’s unavailable when linking musl statically (which we do for the compiler).

Ah, If I understand correctly, libdl ships with libc (which Crystal uses musl because glibc doesn’t work with static linking well?), and the since libdl isn’t available when linking statically, could it be provided with the binary?

Would that require building musl along with static Crystal and exporting them together? Or are there other challenges?

It doesn’t seem to matter too much, as this only appears to be a problem with using a static build. I can do a dynamic build on my own without much problems.

[lemmuh]

Is the interpreter also be available on windows ?

[kojix2]

What made me happy today is that I can now use the Crystal interpreter installed with apt install crystal on my new Ubuntu 24.04 (Noble Numbat) . I always wanted an interpreter, so I used to build Crystal from source and use sudo checkinstall, but that may not be necessary anymore.

I don’t know who contributed to this, but I’m very grateful. Thank you!

[straight-shoota]

That would be @deiv, according to https://changelogs.ubuntu.com/changelogs/pool/universe/c/crystal/crystal_1.11.2+dfsg-1build3/changelog

crystal (1.9.2+dfsg-2) unstable; urgency=medium

• Recover 1.6.0+dfsg-3 version lost changes (Closes: #1043235).
• Build interpreter again.

– David Suárez deiv@debian.org Tue, 08 Aug 2023 16:24:42 +0200

[deiv]

Welcome ;)

[pfischer]

I have Ubuntu 24.04 and the official crystal packages are definitelly without interpreter support (Crystal was compiled without interpreter support).

My package URI from /etc/apt is:
http://download.opensuse.org/repositories/devel:/languages:/crystal/xUbuntu_24.04/

So… How?

[straight-shoota]

We’re talking about the downstream package in the Ubuntu 24.04 repository: Ubuntu – Details of package crystal in noble

Note that this repository lags behind, though. So you won’t get the latest release.

Our own packages from devel:languages:crystal on OBS will always be up to date. But they don’t have interpreter support yet.

[straight-shoota]

There’s a trick that allows fully-portable yet dynamically linked builds. This could allow us shipping portable builds with the interpreter.

Portable, dynamically linked packages on Linux

This article presents a very clever mechanism for dynamically linked executables to be fully portable, just like a statically linked one would be. https://brioche.dev/blog/portable-dynamically-linked-packages-on-linux/ TL;DR: The executable needs to ship with all dynamically linked libraries and the necessary ELF-interpreter (ld-linux.so). The magic happens in a tiny, statically linked bootstrap program which exec’s the ELF-interpreter as userspace exec for a correct /proc/self/exe and with li…