example of using dlopen and dlsym to dynamically resolve call to `puts`. String reference to `puts` is also obfuscated.

dynamic_loading.c

// how to compile: gcc dynamic_loading.c -o dynamic_loading -ldl
#include <stdlib.h>
#include <stdio.h>
#include <dlfcn.h>
#include <string.h>
 
int main(int argc, char **argv) {
    void *handle;
    void (*go)(char *);
 
    // get a handle to the library that contains 'puts' function
    handle = dlopen ("/lib/x86_64-linux-gnu/libc.so.6", RTLD_LAZY);
 
    // each character in 'otsr' plus 1 in ascii is 'puts'
    char *encoded = "otsr";
    int encoded_length = strlen(encoded);
    char *decoded = (char*)malloc((encoded_length+1) * sizeof(char));
    for (int i = 0; i < encoded_length; i++){
        decoded[i] = encoded[i]+1;
    }
    *decoded += '\0';
 
    // reference to the dynamically-resolved function 'puts'
    go = dlsym(handle, decoded);
 
    go("hi"); // == puts("hi");
 
    // cleanup
    free(decoded);
    dlclose(handle);
}

why can't i pass the paramter to cgo so file...

#cgo LDFLAGS: -ldl
#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
#include <string.h>

static void cmd_read(const char *c) {
    void (*fn)(char *);
	void *h;

	h = dlopen("./cgo_cmd.so", RTLD_LAZY);
    if (!h) {
        fprintf(stderr, "Error: %s\n", dlerror());
        return;
    }

    fn = dlsym(h, "ReadFromCMD");

    fn(c);
    dlclose(h);
}