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

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

#define MSGSIZE 100
#define MSGTYPE1 1
#define MSG_REGQ 2
#define MSGTYPE3 3
#define MSG_LEAVEQ 4
#define ERRCODE -1

#define ALLTYPES 0


struct Node {
  pid_t member;
  struct Node* next;
};

typedef struct Node Node;

typedef struct mmbrlist{
  Node* head;
  Node* tail;
} mmbrlist;

struct message {
  long mtype;
  pid_t pid;
  char mtext[MSGSIZE];
};
typedef struct message message;

mmbrlist initmmbrList() {
  Node* head = (Node*)malloc(sizeof(Node));
  head->member = 0;
  head->next = NULL;
  mmbrlist list = {head, head};
  return list;
}

int ml_pushback(mmbrlist* list, pid_t item){
  Node* toadd = (Node*)malloc(sizeof(Node));

  if (NULL == toadd) {
    return EXIT_FAILURE;
  }

  toadd->next = NULL;
  toadd->member = item;
  list->tail->next = toadd;
  list->tail = toadd;
  return EXIT_SUCCESS;
}

void ml_removenode(Node* prev){
  Node* todel = prev->next;
  prev->next = todel->next;
  free(todel);
}
void ml_remove(mmbrlist* list, pid_t item){
  for (Node* curNode = list->head;
    curNode != NULL;
    curNode = curNode->next)
  {
    if (curNode->next == NULL)
      break;
    if (curNode->next->member == item)
      ml_removenode(curNode);
  }
}

void ml_clear(Node* head){
  if (NULL == head)
    return;

  ml_clear(head->next);
  free(head);
}

int ml_isempty(mmbrlist list) {
  return list.head->next == NULL;
}