getshm2.c

多用户银行系统

#include "../include/structs.h"
#include "../include/stddef.h"
#include <sys/types.h>
#include <signal.h>
#include <stdio.h>
#include <sys/ipc.h>
#include <unistd.h>
#include <sys/shm.h>
#include <sys/sem.h>
void * getSHM();
int main(int argc,char**argv){
        SHM *shm;
        shm = (SHM*)getSHM();
}
void * getSHM(){
	void *p;
	int shm_id;
	int sem_id;
	//union semun options;
	//struct sembuf lock_it;
	int key;	   
  	char *name = "/dev/shm/myshm2";
	key = ftok(name,0);
	shm_id = shmget(key,0,0);
	sem_id = semget(key,0,0);
	//semctl(sem_id,0,SETVAL,options);
	p = shmat(shm_id,NULL,0);
	*((int *)p) = semctl(sem_id,0,GETVAL,0);
	printf("%d\n",*((int *)p));
	while(1){
		if(*((int *)p)==0){
		p = p+sizeof(int);
		*((int*)p) = 1;
                printf("%d\n",p);
		printf("%d\n",*(int*)p);
                return ((void *)p);
		}
                else{
                        p = p+sizeof(int)+sizeof(SHM);
                        continue;
                }
        }
}