#ifndef COMMON_H_
#define COMMON_H_

#include <stdlib.h>
#include <unistd.h>
#include <errno.h>

#define FIFO_SERVER_PATH "/tmp/fifo.to_server" // server reads this file
#define FIFO_CLIENT_PATH "/tmp/fifo.to_client" // client reads this file

#define __DATA_STRUCT_MSG_LEN 4096

enum ds_types {
    DS_MESSAGE,
    DS_FAIL
};

struct custom_ds {
    struct {
        long len;
        long type;
    } hdr;
    char msg[__DATA_STRUCT_MSG_LEN];
};

static inline ssize_t send_msg(int fd, const struct custom_ds *ds)
{
    return write(fd, ds, sizeof(ds->hdr) + ds->hdr.len);
}

static inline ssize_t recv_msg(int fd, struct custom_ds *reciever)
{
    size_t n_hdr = read(fd, reciever, sizeof(reciever->hdr));
    if (n_hdr == 0) return 0; // eof reached
    if (n_hdr != sizeof(reciever->hdr)) return -ENOMSG;
    if (reciever->hdr.len == 0) return 0;

    size_t n_payload = read(fd, &reciever->msg, reciever->hdr.len);
    if (n_payload != reciever->hdr.len) return -EFAULT;
    return n_hdr + n_payload;
}

#define FAIL_ON(cond) if (cond) return EXIT_FAILURE

#endif