linux-C-信号量

deepfuture-lx@deepfuture-lx-desktop:~/private/mytest$ gcc -std=gnu99 -o testsem testsem.c
testsem.c: In function ‘get_sem_val’:
testsem.c:8: warning: implicit declaration of function ‘semctl’
testsem.c: In function ‘main’:
testsem.c:20: warning: implicit declaration of function ‘semget’
testsem.c:23: warning: implicit declaration of function ‘exit’
testsem.c:23: warning: incompatible implicit declaration of built-in function ‘exit’
testsem.c:31: warning: incompatible implicit declaration of built-in function ‘exit’
testsem.c:34: warning: implicit declaration of function ‘fork’
testsem.c:37: warning: incompatible implicit declaration of built-in function ‘exit’
testsem.c:44: warning: implicit declaration of function ‘semop’
testsem.c:58: warning: incompatible implicit declaration of built-in function ‘exit’
deepfuture-lx@deepfuture-lx-desktop:~/private/mytest$ ./testsem
create 65538 sem success!
0生産者:2
1生産者:3
2生産者:4
3生産者:5
4生産者:6
5生産者:7
6生産者:8
7生産者:9
8生産者:10
9生産者:11
10生産者:11
11生産者:12
12生産者:13
13生産者:14
14生産者:15
0消費者:11
1消費者:14
2消費者:13
3消費者:12
4消費者:11
5消費者:10
6消費者:9
7消費者:8
8消費者:7
9消費者:6
10消費者:5
11消費者:4
12消費者:3
13消費者:2
14消費者:1
deepfuture-lx@deepfuture-lx-desktop:~/private/mytest$ 

#include <stdio.h>
#include <linux/sem.h>
#define MAXNUMS 15


int get_sem_val(int sid,int semnum)//       
{
    return(semctl(sid,semnum,GETVAL,0));
}

int main(void){
    int sem_id;
    int pid;
    int rc;
    struct sembuf sem_op;//     
    union semun sem_val;//     
    
    
    //      ，         
    sem_id=semget(IPC_PRIVATE,1,IPC_CREAT|0600);//IPC_PRIVATE  ，       ，      ，     ；1       ；
    if (sem_id==-1){
        printf("create sem error!
");
        exit(1);    
    }
    printf("create %d sem success!
",sem_id);    
    //      
    sem_val.val=1;
    rc=semctl(sem_id,0,SETVAL,sem_val);//     ,0       ，1       ,...    ；SETVAL    
    if (rc==-1){
        printf("initlize sem error!
");
        exit(1);    
    }
    //    
    pid=fork();
    if (pid==-1){
        printf("fork error!
");
        exit(1);           
    }
    else if(pid==0){//     ，   
        for (int i=0;i<MAXNUMS;i++){
            sem_op.sem_num=0;
            sem_op.sem_op=-1;
            sem_op.sem_flg=0;
            semop(sem_id,&sem_op,1);//     ，  -1                
            printf("%d    : %d
",i,get_sem_val(sem_id,0));
        }     
    }
    else{//   ，   
        for (int i=0;i<MAXNUMS;i++){
            sem_op.sem_num=0;
            sem_op.sem_op=1;
            sem_op.sem_flg=0;
            semop(sem_id,&sem_op,1);//     ，  +1                 
            printf("%d    : %d
",i,get_sem_val(sem_id,0));
            
        }     
    }
    exit(0);
}