#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include "log.h"      //reporting and logging functions


void cleanup();

//variables for indexing of messages by logging functions
int logindex = 0;
int *logi = &logindex;

//variables for shared memory segments
int shmid = -1;            //id
void* shmaddr;             //address where it is attached
struct shmid_ds shmbuf;    //structure with info


/* function main ---------------------------------------------- */
int main()
{

 int i;
 int *p;

 if (atexit(cleanup)<0)
   sys_exit("atexit error");

 if ((shmid = shmget(IPC_PRIVATE,100,S_IRUSR|S_IWUSR))<0)
   sys_exit("shmget error");
 else
   msg("shared memory segment of size 100 with id=%d created\n",
       shmid);

 shmaddr = shmat(shmid,(const void *)0,S_IRUSR|S_IWUSR);
 if (((int)(shmaddr)) == -1)
   sys_exit("shmat(%d,.....) error",shmid);
 else
   msg("shared memory segment id=%d attached at address %u\n",
       shmid,shmaddr);

 // store int 235 in it
 p = shmaddr;
 *p = 235;

 //fetch the value from it
 msg("int value stored in the shared memory segment is %d\n",*p);

 exit(0);

}/* end main */



/* function cleanup --------------------------------------------- */
void cleanup()
{
 if (shmid >= 0) {
   if (shmctl(shmid,IPC_RMID,&shmbuf)<0)
     sys("shmctl(%d,IPC_RMID,...) error",shmid);
   else
     msg("shared memory segment id=%d removed\n",shmid);
 }

}/* end cleanup */