Problems linking against native libraries

[noncom]

With my current project I've stepped into a problem with native libraries. The issue is that lwjgl cannot find its natives although the jar with the natives is properly linked to the project and appears in Leiningen Dependencies.

I have made a little research and found out that this problem is known for lwjgl:

1. http://wiki.lwjgl.org/wiki/Downloading_and_Setting_Up_LWJGL look at the "I keep getting an java.lang.UnsatisfiedLinkError: no lwjgl in java.library.path" paragraph

2. this is how it is solved normally in eclipse: http://stackoverflow.com/questions/19344914/getting-java-lang-unsatisfiedlinkerror-no-lwjgl-in-java-library-path

3. and the official guide: http://wiki.lwjgl.org/index.php?title=Setting_Up_LWJGL_with_Eclipse (mostly same as point 2), but with neat pictures ).

So, in my project there is the lwjgl natives jar, however, the java lwjgl jar native library path points to "project/target/native/windows/x86_64" and in the project build path setup it says "not modifiable".
The interesting part is that the natives are actually do get extracted and are there ready to be picked up, but they are located at "project/target/native/windows".

Resume: if I manually copy the dlls from "project/target/native/windows" to "project/target/native/windows/x86_64", all starts working okay. I know leiningen and java in general have their quirks in working with native libraries, but what is different in this case, is that the path "project/target/native/windows/x86_64" is incorrect and cannot be changed. Is there something in CCW that is getting in touch with this?

---

A small GitHub project illustrating the issue: https://github.com/noncom/test-natives
Upon loading the core ns into the repl, you'll get:

;; Clojure 1.6.0
<Namespace test-natives.core>
CompilerException java.lang.UnsatisfiedLinkError: no lwjgl in java.library.path, compiling:(test_natives\core.clj:4:3)

and if you move the natives as I've described above, it will compile fine. even calling (go) will work ok and return nil. It does not matter that you have no actual opengl context active

[laurentpetit]

thanks, I will take a look at it

[laurentpetit]

I have the same problem with leiningen on the command line, no need to reach for ccw to get the UnstatisfiedLinkError exception.

[laurentpetit]

And as you suggested, moving my target/natives/macosx/ files to target/natives/macosx/x86_84 files did the trick and now leiningen on the command line works again

[laurentpetit]

There's a word about lwjgl in the leiningen samples project.clj, by the way:

https://github.com/technomancy/leiningen/blob/master/sample.project.clj#L55

[laurentpetit]

Please, talk about this issue with the Leiningen folks first. There's a lot on my plate these days, it would be good if you could confirm that you also get the same problem with leiningen, and then maybe find a solution, or some workaround.
Then we'll be able to see if this work-around can or cannot be embedded into CCW.
Deal?

[noncom]

Alright! I will do experiments with Leiningen first and see if it is possible to get a fix from some manipulations with it. Eh, I am sorry that I have loaded you with this one, since it apparently is a core Leiningen issue... on the other hand, I think a user expects his IDE to handle such things automatically... the case seems vague, I'll explore more and report when I have some results on this.

[laurentpetit]

You did the right thing, don't worry. Thanks for exploring the case.

2015-08-17 12:37 GMT+02:00 noncom notifications@github.com:

Alright! I will do experiments with Leiningen first and see if it is
possible to get a fix from some manipulations with it. Eh, I am sorry that
I have loaded you with this one, since it apparently is a core Leiningen
issue... on the other hand, I think a user expects his IDE to handle such
things automatically... the case seems vague, I'll explore more and report
when I have some results on this.

—
Reply to this email directly or view it on GitHub
#836 (comment).

Laurent Petit

[noncom]

Small update: specifying :native-path "target/native/native/windows" in project.clj makes it work. Not sure what that means though. With this parameter specified and even Leiningen project reset in CCW, the Eclipse dependencies window still shows project/target/native/windows/x86_64, non modifiable, but this time compilation works.

I am still contemplating on this...

[laurentpetit]

So to summarize :

• now it works on windows with leiningen on the command line
• but CCW is unable to derive the right native path

2015-08-20 15:23 GMT+02:00 noncom notifications@github.com:

Small update: specifying :native-path "target/native/native/windows" in
project.clj makes it work.Not sure what that means though. With this
parameter specified and even Leiningen project reset in CCW, the Eclipse
dependencies window still shows project/target/native/windows/x86_64, non
modifiable, but this time compilation works.

I am still contemplating on this...

—
Reply to this email directly or view it on GitHub
#836 (comment).

Laurent Petit

[noncom]

Yes, it works in Windows command line Leiningen, as well as from CCW if "launch projects with Leiningen" is enabled - same. However, if I uncheck "launch projects with Leiningen", it looks like that CCW goes with what Eclipse is saying in the deps and does not find the libs, failing as before.

Idk if there is even a solution for that. Probably this is a quirk of dealing with the lwjgl library in particular.. As hyPiRion said on #leiningen, not many people work with native deps and this area is highly underdocumented and it is unknown if some uniformity (i.e. a generalized solution) can be applied to the area at all. If it will become clear that it is impossible to formalize a universal approach for this situation, then maybe a plugin for CCW+LWJGL could be considered. Because the problem is there and other people can stumble upon it and there is not much info on this..

[laurentpetit]

@noncom which version of leiningen are you using on the command line?

[laurentpetit]

@noncom also, can you please update the github project test-natives with the fix you found?

[laurentpetit]

I still cannot make it work on the command line.
Here's what I do:

• clone the test-natives repository
• cd into test-natives
• immediately invoke lein repl
• then (require 'test-natives.core) and it fails saying CompilerException java.lang.UnsatisfiedLinkError: no lwjgl in java.library.path, compiling:(test_natives/core.clj:4:3)

Then I check the target directory, and there's nothing inside it.

• Same thing whether I add or do not add the :native-path "target/native/native/macosx" to project.clj (I changed windows to macosx for my platform).
• Same thing with leiningen version 2.5.0 2.5.1 2.5.2.

So I may be missing the obvious, which is ... ?