刚刚看到一个关于信号量的例子,怎么运行起来没有反应?

prayerwy2046

2.1 服务器

#include <sys/sem.h>
#include <sys/ipc.h>

#define SEGSIZE 1024
#define READTIME 1
union semun {
int val;
struct semid_ds *buf;
unsigned short *array;
} arg;
//生成信号量
int sem_creat(key_t key)
{
union semun sem;
int semid;
sem.val = 0;
semid = semget(key,1,IPC_CREAT|0666);
if (-1 == semid){
  printf("create semaphore error\n");
  exit(-1);
}
semctl(semid,0,SETVAL,sem);
return semid;
}
//删除信号量
void del_sem(int semid)
{
union semun sem;
sem.val = 0;
semctl(semid,0,IPC_RMID,sem);
}

//p
int p(int semid)
{
struct sembuf sops={0,+1,IPC_NOWAIT};
return (semop(semid,&sops,1));
}
//v
int v(int semid)
{
struct sembuf sops={0,-1,IPC_NOWAIT};
return (semop(semid,&sops,1));
}
int main()
{
key_t key;
int shmid,semid;
char *shm;
char msg[7] = "-data-";
char i;
struct semid_ds buf;

key = ftok("/",0);
shmid = shmget(key,SEGSIZE,IPC_CREAT|0604);
if (-1 == shmid){
  printf(" create shared memory error\n");
  return -1;
}
shm = (char *)shmat(shmid,0,0);
if (-1 == (int)shm){
  printf(" attach shared memory error\n");
  return -1;
}
semid = sem_creat(key);
for (i = 0;i <= 3;i++){
  sleep(1);
  p(semid);
  sleep(READTIME);
  msg[5] = '0' + i;
  memcpy(shm,msg,sizeof(msg));
  sleep(58);
  v(semid);
}
shmdt(shm);
shmctl(shmid,IPC_RMID,&buf);
del_sem(semid);
return 0;
//gcc -o shm shm.c -g
}

2.2 客户端

#include <sys/sem.h>
#include <time.h>
#include <sys/ipc.h>

#define SEGSIZE 1024
#define READTIME 1
union semun {
int val;
struct semid_ds *buf;
unsigned short *array;
} arg;

// 打印程序执行时间
void out_time(void)
{
static long start = 0;
time_t tm;
if (0 == start){
  tm = time(NULL);
  start = (long)tm;
  printf(" now start ...\n");
}
printf(" second: %ld \n",(long)(time(NULL)) - start);
}

//创建信号量
int new_sem(key_t key)
{
union semun sem;
int semid;
sem.val = 0;
semid = semget(key,0,0);
if (-1 ==  semid){
  printf("create semaphore error\n");
  exit(-1);
}
return semid;
}

//等待信号量变成0
void wait_v(int semid)
{
struct sembuf sops={0,0,0};
semop(semid,&sops,1);
}

int main(void)
{
key_t key;
int shmid,semid;
char *shm;
char msg[100];
char i;

key = ftok("/",0);
shmid = shmget(key,SEGSIZE,0);

if(-1 == shmid){
  printf(" create shared memory error\n");
  return -1;
}
shm = (char *)shmat(shmid,0,0);
if (-1 == (int)shm){
  printf(" attach shared memory error\n");
  return -1;
}
semid = new_sem(key);
for (i = 0;i < 3;i ++){
  sleep(2);
  wait_v(semid);
  printf("Message geted is: %s \n",shm + 1);
  out_time();
}
shmdt(shm);
return 0;
// gcc -o shmc shmC.c -g
}


我把两个程序都执行了，可是没有反应