io+day8

 

 #ifndef __SEM2 #define __SEM3 4 //声明一个创>5 int init_sem(6 7 //声明一个p操8 int P(int sem9 10 //声明一个v操11 int W(int sem12 13 //声明一个删>14 int del_sem(i15 16 #endif

1 #include <myhead.h>                                                                                                                           2 union semun {3     int              val;    /* Value for SETVAL */4     struct semid_ds *buf;    /* Buffer for IPC_STAT, IPC_SET */5     unsigned short  *array;  /* Array for GETALL, SETALL */6     struct seminfo  *__buf;  /* Buffer for IPC_INFO7                     (Linux-specific) */8 };9 //信号灯集里每个信号灯的初始化10 int sem_value(int semid,int semno,int semvalue)11 {12     union semun us;13     us.val=semvalue;14     if(semctl(semid,semno,SETVAL,us)==-1)15     {16         perror("semctr");17         return -1;18     }19     return 0;20 }21 //创建信号灯集并初始化函数22 int init_sem(int semnum)23 {24     //1.创建一个key钥匙25     key_t key;26     if((key=ftok("/",'t'))==-1)27     {28         perror("ftok");29         return -1;30     }31     //2.创建一个信号灯集32     int semid;33     if((semid=semget(key,semnum,IPC_CREAT|IPC_EXCL|0664))==-1)34     {35         if(errno==EEXIST)36         {37             //防止多进程同时调用时多次初始化38             semid=semget(key,semnum,IPC_CREAT|0664);39             return semid;40         }41         perror("semget");42         return -1;43     }44     //3.信号灯集初始化45     for(int i=0;i<semnum;i++)46     {47         if(i==0)48         {49             //参数1:id50             //参数2:初始化的信号灯编号51             //参数3:初始化的信号灯的value值52             sem_value(semid,i,1);53         }54         else55         {56             sem_value(semid,i,0);57         }58     }59     return semid;60 }61 62 //p操作函数63 int P(int semid,int semno)64 {65     struct sembuf buf;66     buf.sem_num=semno;//灯集里灯编号67     buf.sem_op=1;  //释放资源68     buf.sem_flg=0; //阻塞69     if(semop(semid,&buf,1)==-1)70     {71         perror("semop");72         return -1;73     }74     return 0;75 76 }77 //w操作函数78 int W(int semid,int semno)79 {80         struct sembuf buf;81         buf.sem_num=semno;//灯集里灯编号82         buf.sem_op=-1;  //申请资源83         buf.sem_flg=0; //阻塞84         if(semop(semid,&buf,1)==-1)85         {86                 perror("semop");87                 return -1;88         }89         return 0;90 }91 92 //删除信号灯的函数93 int del_sem(int semid)94 {95     if(semctl(semid,0,IPC_RMID,0)==-1)96     {97         perror("semctl");98         return -1;99     }
100     return 0;
101 }

1 #include <myhead.h>2 #include "sem.h"3 int main(int argc, const char *argv[])4 {5     //创建钥匙6     key_t key=-1;7     if((key=ftok("/",'c'))==-1)8     {9         perror("ftok");10         return -1;11     }12     //创建共享享内存13     int shmid;                                 14     if((shmid=shmget(key,4096,IPC_CREAT|0664))=15     {16         perror("shmget");17         return -1;18     }   19     //映射到用户空间20     char *adder;21     if((adder=shmat(shmid,NULL,0))==(void *)-1)22     {23         perror("shmat");24         return -1;25     }   26     //创建一个信号灯集27     int semid;28     semid=init_sem(4);29     //创建父子进程30     pid_t pid;31     pid=fork();32     if(pid<0)33     {   34         perror("fork");35         return -1;36     }   37     else if(pid>0)38     {   39         //父进程40         while(1)41         {42             //等待0信号资源43             W(semid,0);44             fgets(adder,4096,stdin);45             adder[strlen(adder)-1]='\0';46             //释放1信号资源47             P(semid,1);48             if(strcmp(adder,"quit")==0)49             {50                 break;51             }   52         }53         wait(NULL);54     }   55     else    56     {   57         //子进程58         while(1)59         {   60             //等待3信号资源61             W(semid,3);62             //房子里面拿东西63             printf("共享内存数据:%s\n",adder);64                     //释放2信号资源65                     P(semid,2);66             if(strcmp(adder,"quit")==0)67             {68                 break;69             }   70         }   71         exit(EXIT_SUCCESS);72     }   73     //取消链接74     shmdt(adder);75     return 0;76 }