#include <stdio.h>
#include <stdint.h>

struct _blablabla_private {
    char *whatever1;
    size_t whatever2;
    size_t whatever3;
    size_t whatever4;
    char *whatever5;
    int *whatever6; 
};

struct blablabla {
   char data_[sizeof(struct _blablabla_private)];
};

void lib_func_set(struct blablabla* bla) {
	struct _blablabla_private *priv = (struct _blablabla_private *)bla->data_;
	priv->whatever1 = "it works";
}

void lib_func_get(const struct blablabla* bla) {
	struct _blablabla_private *priv = (struct _blablabla_private *)bla->data_;
	printf("%s\n", priv->whatever1);
}

int main(void) {
	struct blablabla b;
	
	lib_func_set(&b);
	lib_func_get(&b);

	return 0;
}