server.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>

#include "message.h"

const char* shar_object = "posix-shar-object";

void sys_err (char *msg) {
  puts (msg);
  exit (1);
}

int keepRunning = 1;
void intHandler(int dummy) {
    keepRunning = 0;
}

int main () {
  int shmid;
  message_t *msg_p;

  if ( (shmid = shm_open(shar_object, O_CREAT|O_RDWR, 0666)) == -1 ) {
    perror("shm_open");
    sys_err ("server: object is already open");
  } else {
    printf("Object is open: name = %s, id = 0x%x\n", shar_object, shmid);
  }
  if (ftruncate(shmid, sizeof (message_t)) == -1) {
    perror("ftruncate");
    sys_err ("server: memory sizing error");
    return 1;
  } else {
    printf("Memory size set and = %lu\n", sizeof (message_t));
  }

  msg_p = mmap(0, sizeof (message_t), PROT_WRITE|PROT_READ, MAP_SHARED, shmid, 0);
  if (msg_p == (message_t*)-1 ) {
  }

  signal(SIGINT, intHandler);
  msg_p->type = MSG_TYPE_EMPTY;
  while (1) {
    if (keepRunning) {
      if (msg_p->type != MSG_TYPE_EMPTY) {
        if (msg_p->type == MSG_TYPE_STRING) {
          printf ("%d\n", msg_p->n);
        } else if (msg_p->type == MSG_TYPE_FINISH) {
          break;
        }
        msg_p->type = MSG_TYPE_EMPTY;
      }
    } else {
      msg_p->type = MSG_TYPE_FINISH;
    }
  }

  if(shm_unlink(shar_object) == -1) {
    perror("shm_unlink");
    sys_err ("server: error getting pointer to shared memory");
  }
  return 0;
}