無名信号量實作相關程序同步

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <semaphore.h>
#include <sys/mman.h>
#define COUNTNO 20
sem_t sem;
sem_t *psem = NULL;
int main(int argc, char *argv[])
{
    int pid,i;
    int val;
        //記憶體映射實作信号量共享
    psem = (sem_t *)mmap(NULL, sizeof(sem_t), PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -, );        
    if (psem == NULL)
    {
        printf("Share memory failed!\n");
        return -;
    }   
    if (sem_init(psem, , ) == -)
    {
        printf("Init unamed sem failed!\n");
        return -;
    }
    sem_getvalue(psem,&val);        
    printf("this is the main function the psem value is %d\n",val); 

    pid = fork();
    if(pid==){  
        for (i=;i<COUNTNO;i++) 
        {    
            //sem_wait(psem);       //相當于P操作
             sleep();
            sem_getvalue(psem,&val);        

            printf("this is child,the count num  is %d\n",i);   
            sem_post(psem);         //相當于V操作

        }  
    } 
    else { 
        for (i=;i<COUNTNO;i++) 
    {   
        sem_wait(psem);  
        sem_getvalue(psem,&val);        

        printf("this is father,the sem count num is %d\n",i);   
        //sem_post(psem);  

    }
    }   
    sem_destroy(psem);
    return ;
}