进程间通信之：实验内容
/*将共享内存地址映射到当前进程地址空间*/
shared_memory=shmat(shmid,(void*)0,0);
if(shared_memory==(void*)-1)
{
perror(shmat);
del_sem(semid);
exit(1);
}
printf(Memoryattachedat%Xn,(int)shared_memory);
/*获得共享内存的映射地址*/
shm_buff_inst=(structshared_use_st*)shared_memory;
do
{
sem_p(semid);
printf(Entersometexttothesharedmemory(enter'quit'toexit):);
/*向共享内存写入数据*/
if(fgets(shm_buff_inst->buffer,SHM_BUFF_SZ,stdin)==NULL)
{
perror(fgets);
sem_v(semid);
break;
}
shm_buff_inst->pid=getpid();
sem_v(semid);
}while(strncmp(shm_buff_inst->buffer,quit,4)!=0);
/*删除信号量*/
del_sem(semid);
/*删除共享内存到当前进程地址空间中的映射*/
if(shmdt(shared_memory)==1)
{
perror(shmdt);
exit(1);
}
exit(0);
}
以下是“消费者”程序部分。
/*customer.c*/
#includeshm_com.h
#includesem_com.h
intmain()
{
void*shared_memory=NULL;
structshm_buff*shm_buff_inst;
intshmid,semid;
/*获得信号量*/
semid=semget(ftok(.,'a'),1,0666);
if(semid==-1)
{
perror(Producerisntexist);
exit(1);
}
/*获得共享内存*/
shmid=shmget(ftok(.,'b'),sizeof(structshm_buff),0666|IPC_CREAT);
if(shmid==-1)
{
perror(shmget);
exit(1);
}
/*将共享内存地址映射到当前进程地址空间*/
shared_memory=shmat(shmid,(void*)0,0);
if(shared_memory==(void*)-1)
{
perror(shmat);
exit(1);
}
printf(Memoryattachedat%Xn,(int)shared_memory);
/*获得共享内存的映射地址*/
shm_buff_inst=(structshm_buff*)shared_memory;
do
{
sem_p(semid);
printf(Sharedmemorywaswrittenbyprocess%d:%s
,shm_buff_inst->pid,shm_buff_inst->buffer);
if(strncmp(shm_buff_inst->buffer,quit,4)==0)
{
break;
}
shm_buff_inst->pid=0;
memset(shm_buff_inst->buffer,0,SHM_BUFF_SZ);
sem_v(semid);
}while(1);
/*删除共享内存到当前进程地址空间中的映射*/
if(shmdt(shared_memory)==-1)
{
perror(shmdt);
exit(1);
}
/*删除共享内存*/
if(shmctl(shmid,IPC_RMID,NULL)==-1)
{
perror(shmctl(IPC_RMID));
exit(1);
}
exit(0);
}
4．实验结果
$./producer
MemoryattachedatB7F90000
Entersometexttothesharedmemory(enter'quit'toexit):Firstmessage
Entersometexttothesharedmemory(enter'quit'toexit):Secondmessage
Entersometexttothesharedmemory(enter'quit'toexit):quit
$./customer
MemoryattachedatB7FAF000
Sharedmemorywaswrittenbyprocess3815:Firstmessage
Sharedmemorywaswrittenbyprocess3815:Secondmessage
Sharedmemorywaswrittenbyprocess3815:quit
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