#include <stdio.h>

#include <sys/ipc.h>

#include <sys/sem.h>

#include <string.h>

#define SEM_NUM 5                                       // 信号量的个数

// 创建一个信号集

int main()

{

        key_t key;

        key = ftok("test", 1);                          // 创建key

        if (key == -1) {

                perror("fail ftok");

                return -1;

        }

        int semid;

        semid = semget(key, 5, IPC_CREAT | 0664);       // 创建一个包含5个信号量的信号集

        if (semid == -1) {

                perror ("fail semget");

                return -1;

        }

        printf("semid: %d\n", semid);

        return 0;

}

#include <stdio.h>

#include <sys/ipc.h>

#include <sys/sem.h>

#include <string.h>

#include <stdlib.h>

#define SEM_NUM 5

void initSemaphore(int semid)

{

        unsigned short semInit[SEM_NUM];

        printf("init [%d] semaphore: ", SEM_NUM);

        int i;

        for (i = 0; i != SEM_NUM; i++) {

                int n;

                scanf("%d", &n);

                semInit[i] = n;

        }

        semctl(semid, SEM_NUM, SETALL, semInit);

}

void semop_PVZ(int semid, char flag)

{

        struct sembuf sops[SEM_NUM];

        int arr[SEM_NUM];

        int isign = 1;

        switch(flag) {

                case 'p':

                        isign = -1;

                        break;

                case 'v':

                        isign = 1;

                        break;

                case 'z':

                        isign = 0;

                        break;

                case 'i':

                        initSemaphore(semid);

                        return;

                default:

                        return;

        }

        setbuf(stdout, NULL);

        while(1) {

                printf("[%c]:", flag);

                scanf ("%d%d%d%d%d", arr, arr + 1, arr + 2, arr + 3, arr + 4);

                int i = 0;

                int cnt = 0;

                for (i = 0; i != SEM_NUM; i++) {

                        if (arr[i] == 0) {

                                continue;

                        }

                        sops[cnt].sem_num = i;

                        sops[cnt].sem_op = arr[i] * isign;

                        sops[cnt].sem_flg = 0;

                        cnt++;

                }

                int iRet;

                iRet = semop(semid, sops, cnt);

                if (iRet == -1) {

                        perror("fail semop");

                        return;

                }

        }

}

int main(int argc, char **argv)

{

        if (argc != 2 ||

                (strcmp(argv[1], "p") && strcmp(argv[1], "v")

              && strcmp(argv[1], "q") &&strcmp(argv[1], "z")

              && strcmp(argv[1], "i")))

        {

                printf("Usage: %s [ p | v | q | z | i ]\n", argv[0]);

                printf("\tp: p operator\n");

                printf("\tv: v operator\n");

                printf("\tq: query semaphore value\n");

                printf("\tz: z operator\n");            // z操作既不释放资源，也不申请资源，只做一个判断和等待信号量变为0

                printf("\ti: init semaphore\n");

                return -1;

        }

        key_t key;

        key = ftok("a", 1);

        if (key == -1) {

                perror("fail ftok");

                return -1;

        }

        int semid;

        semid = semget(key, SEM_NUM, IPC_CREAT | 0664);

        if (semid == -1) {

                perror("fail semget");

                return -1;

        }

        // 查询信号集内的各个信号量的值

        if (argv[1][0] == 'q') {

                unsigned short array[SEM_NUM];                  // 存放信号量的值

                int i;

                semctl(semid, SEM_NUM, GETALL, array);

                printf("semaphore value:");

                for (i = 0; i < SEM_NUM; i++) {

                        printf(" %d", array[i]);

                }

                printf("\n");

        }

        else {

                semop_PVZ(semid, argv[1][0]);

        }

        return 0;

}