Hi, I'm new to kotlin-native and trying to underst...

# kotlin-native

[Francesco Pedron]

Hi, I'm new to kotlin-native and trying to understand if I'm able to interact with a DLL on a windows environment.
To understand if it is possible (it seems so) I've built curl from source (to get a sample DLL, I'm going to work with a different one on the actual project) and linked it in my project following what is done on ktor-client-curl.
Something seems to work as I am able to build the project and some klibs (e.g. http-client-cinterop-libcurl.klib) are generated.
Build starts failing when i try to call some method from the DLL, for example in my main method I call:

curl_easy_init()

When this line is added I get this error on build:

The C:\Users\Francesco\.konan\dependencies\llvm-11.1.0-windows-x64-essentials/bin/clang++ command returned non-zero exit code: 1.
output:
lld: error: unable to find library -lcurl
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

This is my libcurl.def:

package = libcurl
headers = curl.h
headerFilter = *
linkerOpts.mingw_x64 = -LC:/msys64/mingw64/lib -LC:/Tools/msys64/mingw64/lib -lcurl -L/opt/homebrew/opt/curl/include/curl
compilerOpts.mingw_x64 = -IC:/msys64/mingw64/include/curl -IC:/Tools/msys64/mingw64/include/curl

Please let me know if someone has some clues on how to get it working or if I can provide more information. Thanks.
This is a repo with my current project: https://github.com/francescopedronomnys/kotlin-native-libcurl-dll

Something that I find strange is that this is part of libcurl.def as defined on ktor-client-curl:

linkerOpts.mingw_x64 = -LC:/msys64/mingw64/lib -LC:/Tools/msys64/mingw64/lib -LC:/Tools/msys2/mingw64/lib -lcurl -L/opt/homebrew/opt/curl/include/curl
compilerOpts.mingw_x64 = -I/usr/include/curl -I/usr/include/x86_64-linux-gnu/curl -I/opt/homebrew/opt/curl/include/curl

I do not understand if those paths on compilerOpts.mingw_x64 are correct or just a copy/paste error, to me they don't look like Windows paths and so on my libcurl.def I've set the path where curl's dll, lib and headers are (C:/Tools/msys64/mingw64)

[msink]

AFAIK if you have in .def file:

-LC:/Tools/msys64/mingw64/lib -lcurl

linker will look for

C:/Tools/msys64/mingw64/lib/libcurl.dll.a

import library.

[Francesco Pedron]

Hello @msink I have no libcurl.dll.a , this is what I have inside lib folder:

Directory: C:\Tools\msys64\mingw64\lib


Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----        12/01/2022     17:46          11415 libcurl.exp
-a----        12/01/2022     17:46          19226 libcurl.lib

What I tried to do now is changing -lcurl to -llibcurl inside .def file and it works! Let me know if it makes sense to you.
Here's the commit that made it work: https://github.com/francescopedronomnys/kotlin-native-libcurl-dll/commit/3b1ffbd5cdc9beb394d3dfbc5171e71f962f01d7

I also found out that I have to put libcurl.dll in

C:\Windows\System32

to make it work at runtime, otherwise the exe will exit immediately.

[msink]

Your libcurl.lib is import library for libcurl.dll ?
Then AFAIK what should work in your case is -l:libcurl.lib

[msink]

-llibcurl is something weird... then linker should look for liblibcurl.a or something similar.

[msink]

About .dll - in runtime it should be in same folder with .exe, or somewhere in system PATH

[Francesco Pedron]

Thank you very much!
I can confirm both -l:libcurl.lib instead of -llibcurl and the hint about the .dll in the same folder as exe.