int sem_init()
{
int ret, semid;
int status = 0;
semid = creat_sem(1, &status);
if (semid == -1)
return -1;
if (status == 3)
return semid;
ret = semctl(semid, 0, SETVAL, 1);
if (ret == -1) {
perror("semctl");
return -1;
}
return semid;
}
int main (int argc, char ** argv) {
long i , k , temp;
long * ptz ;
int p1 , p2, p3, p4;
int ipc_key, ipc_result ;
int mutex; // id du semaphore
if (argc<2)
exit(1) ;
ipc_key = atoi(argv[1]) ;
ipc_result = shmget(ipc_key, 0 , 0) ; // ouverture mémoire partagée
ptz = (long *) shmat(ipc_result, 0, SHMEM_RIGHTS) ; // attachement mémoire partagée
// creation du semaphore mutex
if((mutex = creat_sem(ipc_key+1,1)) == -1)
erreur("erreur creation semaphore");
if ((p1 = fork()) == 0) {
for(i=0;i<10;i++) {
P(mutex); //__________________________
temp = * ptz;
temp++;
sleep( rand() % 2 ); // attente aléatoire
*ptz = temp; ;
V(mutex); //________________________________
//(*ptz) ++ ;
}
exit(0) ;
}
if ((p2 = fork()) == 0) {
for(i=0;i<10;i++) {
P(mutex); //__________________________
temp = * ptz;
temp++;
sleep( rand() % 2 ); // attente aléatoire
*ptz = temp;
V(mutex); //________________________________
}
exit(0) ;
}
if ((p3 = fork()) == 0) {
for(i=0;i<10;i++) {
P(mutex); //__________________________
temp = * ptz;
temp++;
sleep( rand() % 2 ); // attente aléatoire
*ptz = temp;
V(mutex); //________________________________
//(*ptz) ++ ;
}
exit(0) ;
}
if ((p4 = fork()) == 0) {
for(i=0;i<10;i++) {
P(mutex); //__________________________
temp = * ptz;
temp++;
sleep( rand() % 2 ); // attente aléatoire
*ptz = temp; ;
//(*ptz) ++ ;
V(mutex); //________________________________
}
exit(0) ;
}
// while(wait(0) != -1); si le père attend que tous ses fils soient terminés
// suppression du semaphore
//del_sem(mutex);
printf("\n Arret processus pid = %d compteur ( %d ) \n\n", getpid(), *ptz) ;
exit(0) ;
}
int main()
{
key_t key;
int shmid, semid, msqid;
char *shm;
char data[] = "this is server";
struct shmid_ds buf1; /*用于删除共享内存*/
struct msqid_ds buf2; /*用于删除消息队列*/
struct msg_form msg; /*消息队列用于通知对方更新了共享内存*/
// 获取key值
if((key = ftok(".", 'z')) < 0)
{
perror("ftok error");
exit(1);
}
// 创建共享内存
if((shmid = shmget(key, 1024, IPC_CREAT|0666)) == -1)
{
perror("Create Shared Memory Error");
exit(1);
}
// 连接共享内存
shm = (char*)shmat(shmid, 0, 0);
if((int)shm == -1)
{
perror("Attach Shared Memory Error");
exit(1);
}
// 创建消息队列
if ((msqid = msgget(key, IPC_CREAT|0777)) == -1)
{
perror("msgget error");
exit(1);
}
// 创建信号量
semid = creat_sem(key);
// 读数据
while(1)
{
msgrcv(msqid, &msg, 1, 888, 0); /*读取类型为888的消息*/
if(msg.mtext == 'q') /*quit - 跳出循环*/
break;
if(msg.mtext == 'r') /*read - 读共享内存*/
{
sem_p(semid);
printf("%s\n",shm);
sem_v(semid);
}
}
// 断开连接
shmdt(shm);
/*删除共享内存、消息队列、信号量*/
shmctl(shmid, IPC_RMID, &buf1);
msgctl(msqid, IPC_RMID, &buf2);
del_sem(semid);
return 0;
}
int main(void)
{
int semid, shmid;
char buf[STR_LEN] = {0};
void *pshm_addr = NULL;
shm_t * pshm = NULL;
int i = 0;
/*获取信号量标识符*/
semid = creat_sem( );
if(semid == -1)
{ printf("%s : semid = %d!\n", __func__, semid);
return -1;
}
/*获取共享内存标识符*/
shmid = shmget(ftok(FTOK_FILE,111), sizeof(shm_t), IPC_CREAT|0666);
if(shmid == -1)
{
printf("%s: shmid = %d!\n", __func__, shmid);
return -1;
}
/*当前进程连接该共享内存段*/
pshm_addr = shmat(shmid, 0, 0);
if(pshm_addr == (void *)-1)
{
printf("%s : pshm_addr = (void*)-1!\n",__func__);
return -1;
}
pshm = pshm_addr;
printf("read process : semid is %d, shmid is %d!\n",semid, shmid);
for(; ;)
{
/*占用信号量，p操作*/
if(sem_p(semid))
{
printf("%s : sem_p failed !\n",__func__);
return -1;
}
printf("enter write process!\n");
printf("enter something, end with end >\n");
fgets(buf, STR_LEN, stdin);
pshm->num = i++;
strcpy(pshm->buf, buf);
printf("leave write process!\n\n");
/*释放信号量，v操作*/
if(sem_v(semid))
{
printf("%s : sem_v failed!\n",__func__);
return -1;
}
if(!strncmp(pshm->buf , "end", 3))
break;
sleep(2);
}
/*进程和共享内存脱离*/
if(shmdt(pshm_addr) == -1)
{
printf("%s : shmdt is failed!\n",__func__);
return -1;
}
printf(" Good Bye! \n");
return 0;
}