Loading c library from c# with pinvoke on dotnet core

Question

I built the following c library:

#define _GNU_SOURCE
#include <pthread.h>
#include <sched.h>

int attachCurrentThreadToCore(int core);

int main(void) {
    return 0;
}

int attachCurrentThreadToCore(int core) {

    pthread_t thread;

    thread = pthread_self();

    cpu_set_t set;

    CPU_ZERO(&set);

    CPU_SET(core, &set);

    return pthread_setaffinity_np(thread, sizeof(cpu_set_t), &set);
}

and now I am trying to pinvoke attachCurrentThreadToCore.

This is my pinvoke test code:

    [DllImport("/home/anon/Documents/RadFramework/RadFramework.Libraries.Threading/src/TestProject1/bin/Debug/net5.0/pthreadWrapper")]
    
    private static extern int attachCurrentThreadToCore(int core);
    
    [Test]
    public void Test1()
    {
        attachCurrentThreadToCore(0);
        while (true)
        {
        }
    }

Now I would expect core 1 on my machine to spin in the while loop. Instead I receive this exception when pinvoking:

Unable to load shared library '/home/anon/Documents/RadFramework/RadFramework.Libraries.Threading/src/TestProject1/bin/Debug/net5.0/pthreadWrapper' or one of its dependencies. In order to help diagnose loading problems, consider setting the LD_DEBUG environment variable: /home/anon/Documents/RadFramework/RadFramework.Libraries.Threading/src/TestProject1/bin/Debug/net5.0/pthreadWrapper: cannot dynamically load position-independent executable

I think it boils down to "cannot dynamically load position-independent executable".

Is there anything else I need to do when compiling my c library?

Answer 1

Changed the build artifact in eclipse from executable to library:

This results in this build output:

make all Building file: ../src/pthreadWrapper.c Invoking: Cross GCC Compiler gcc -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/pthreadWrapper.d" -MT"src/pthreadWrapper.o" -o "src/pthreadWrapper.o" "../src/pthreadWrapper.c" Finished building: ../src/pthreadWrapper.c

Building target: libPthreadWrapper.so Invoking: Cross GCC Linker gcc -shared -o "libPthreadWrapper.so" ./src/pthreadWrapper.o -lpthread Finished building target: libPthreadWrapper.so

After that the pinvoke is working.