Kotlin/Native Windows cinterop using built library dll - c

Question

I am using Windows to follow the Kotlin-Native libcurl example here https://kotlinlang.org/docs/tutorials/native/curl.html
Unfortunately, this has been a bigger challenge then I could have imagined. I have been learning how to compile C binaries on windows from source using tools such as CMake and have followed this tutorial to build libcurl on Windows: https://jonnyzzz.com/blog/2018/10/29/kn-libcurl-windows/
After quite a few days of trial and error with the .def file for cinterop on Windows, and using compilerOpts to point to my header file for curl in my built library, I have hit a brick wall.
I can't seem to get Gradle to recognize the dll file. Task ':linkDebugExecutableMingw' keeps failing. I have no idea where I am supposed to put the dll file. I have tried putting it in to the build output folder next to the exe, but it still fails to compile, with this error:
C:\Users\yous\.konan\dependencies\msys2-mingw-w64-x86_64-clang-llvm-lld-compiler_rt-8.0.1\bin\ld: C:\Users\yous\AppData\Local\Temp\konan_temp6326583690522756621\result.o:out:(.rdata$.refptr.knifunptr_sample35_curl_easy_strerror[.refptr.knifunptr_sample35_curl_easy_strerror]+0x0): undefined reference to `knifunptr_sample35_curl_easy_strerror'
And a similar list of header file errors, then the final message is:
e: C:\Users\yabde\.konan\dependencies\msys2-mingw-w64-x86_64-clang-llvm-lld-compiler_rt-8.0.1/bin/clang++ invocation reported errors
This is after I succesfully located the header files. I believe this is an issue with the dll file not being included.
Here is my relevant Gradle build script:
mingwX64("mingw") {
compilations.main {
cinterops {
libcurl {
// Def-file describing the native API.
// The default path is src/nativeInterop/cinterop/<interop-name>.def
defFile project.file("src/nativeInterop/cinterop/libcurl.def")
// Package to place the Kotlin API generated.
packageName 'libcurl'
// Options to be passed to compiler by cinterop tool.
compilerOpts '-Isrc\\nativeInterop\\cinterop\\libcurl-vc-x64-release-dll-ipv6-sspi-winssl\\include -o libcurl'
//linkerOpts '-Isrc\\nativeInterop\\cinterop\\libcurl-vc-x64-release-dll-ipv6-sspi-winssl\\bin'
// Directories for header search (an analogue of the -I<path> compiler option).
//includeDirs.allHeaders("path1", "path2")
// Additional directories to search headers listed in the 'headerFilter' def-file option.
// -headerFilterAdditionalSearchPrefix command line option analogue.
includeDirs.headerFilterOnly("src/nativeInterop/cinterop/libcurl-vc-x86-release-dll-ipv6-sspi-winssl/include")
// A shortcut for includeDirs.allHeaders.
//includeDirs("include/directory", "another/directory")
}
}
}
binaries {
executable {
// Change to specify fully qualified name of your application's entry point:
entryPoint = 'sample.main'
// Specify command-line arguments, if necessary:
//runTask?.args('-Lsrc/nativeInterop/cinterop/libcurl-vc-x86-release-dll-ipv6-sspi-winssl/bin')
runTask?.args('')
}
}
}
I believe this issue may be with linker options to locate the dll, but uncommenting the linkerOpts line does not help.
I think I have given up on Kotlin/Native and will be sticking to C for data-oriented native programming...
EDIT:
Also, note that any text commented out is things that I have attempted
Ok so, this is my def file:
headers = curl/curl.h
headerFilter = curl/*
compilerOpts.linux = -I/usr/include -I/usr/include/x86_64-linux-gnu
linkerOpts.osx = -L/opt/local/lib -L/usr/local/opt/curl/lib -lcurl
linkerOpts.linux = -L/usr/lib/x86_64-linux-gnu -lcurl
linkerOpts.mingw = -Llibcurl-vc-x86-release-dll-ipv6-sspi-winssl/lib
Ok so, this is my project structure:

Answer 1

I followed the same steps (jonyzzz blog). I created a Libcurl static example for Kotlin-Native. Support for gzip and SSL. Compile to standalone exe, no need for dll
https://github.com/carlosrafp/Libcurl-Kotlin-Native-standalone
I built the static libraries supplied on the repository with mingw64 (gzip and libcurl) and msys2/mingw (openssl)

Answer 2

I went through this question several times when looking for a solution for statically linking libcurl with my binary.
In the end, I ended up using WinInet for the HTTP communication on Windows. Linux and macOS binary still rely on ktor clients with libcurl.
See my example of how to use WinInet API with Kotlin MPP: https://github.com/localazy/kotlin-mpp-wininet
For a simple HTTP communication, WinInet API is good enough and the resulting binary is much smaller and in my case, it has no additional dependencies.