Question

I know how to pass an unknown amount of arguments from unknown types to a function.
I mean something like this:

char* plugins_entry(const char* data, ...);

Now I am trying to pass a struct besides a few other arguments to that function. I have the same struct declared (or defined?) in both files (main.c and plugins.c). But when I try to “filter” the irc struct passed from the main.c out and parse the data in the irc struct from the plugins.c, I don’t get anything usefull. When I call the function I get a segementation fault.

This is the important part from the main.c:

struct irc_data {
char nick[32];
char user[32];
char host[64];
char chan[32];
char message[512];
int is_ready;
};

....

int main(int argc, char** argv) {
    ....
    struct irc_data *irc = malloc(sizeof(struct irc_data));
    ....
    (*lib_plugin)("r",irc);  // call the function in plugins.c 
    ....
}

And here the hole plugins.c:

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

struct irc_data{
    char nick[32];
    char user[32];
    char host[64];
    char chan[32];
    char message[512];
    int is_ready;
};

char* plugins_entry(const char* data, ...) {
    int i;
    struct irc_data *irc = malloc(sizeof(struct irc_data));

    va_list args;
    va_start(args, data);

    for(i=0; data[i] != '\0'; ++i){
        if(data[i] == 'r'){
            irc = data[i];
        }
    }

    va_end(args);

    printf("\n\n------------------------\n");
    printf("What we got here: %s\n",irc->nick);
    printf("\n------------------------\n\n");


    return "done";
}

So, I am pretty sure that I am doing something wrong with the pointers.

Could you please help me out here?

Thank you

~ Tectu

Answer 1

The line irc = data[i] doesn’t make any sense. You need to call va_arg:

if(data[i] == 'r') {
    irc = va_arg(args, struct irc *);
}

Also, the malloc in plugins_entry is useless, it will only leak memory.