Linux嵌入式-共享内存作业

1、共享内存作业内容：共享内存实验中，代码不能正确运行。请修改代码，并分析原因。代码：1、/*sem_com.h*/#ifndefSEM_COM_H#defineSEM_COM_H#include#includeunionsemunintval;structsemid_ds*buf;unsignedshort*array;；intinit_sem(int,int);intdel_sem(int);intsem_p(int);intsem_v(int);#endif/*SEM_COM_H*/2、/*shm_com.h*/#ifndefSHM_COM_H#defineSHM_COM_H#include

2、#include#include#include#include#include#include#defineSHM_BUFF_SZ2048structshm_buffintpid;charbufferSHM_BUFF_SZ;；#endif/*SHM_COM_H*/3a/*sem_com.c*/#includesem_com.hintinit_sem(intsem_id,intinit_value)unionsemunsem_union;sem_union.val=init_value;if(semctl(sem_id,0,SETVAL,sem_union)=-1)perror(Initial

3、izesemaphore);return-1;return0;intdel_sem(intsem_id)unionsemunsem_union;if(semctl(sem_id,0,IPC_RMID,sem_union)=-1)perror(Deletesemaphore);return-1;intsem_p(intsem_id)structsembufsem_b;sem_b.sem_num=0;/*id*/sem_b.sem_op=-1;/*Poperation*/sem_b.sem_flg=SEM_UNDO;if(semop(sem_id,&sem_b,1)=-1)/*1:firststr

4、uct*/perror(Poperation);return-1;return0;intsem_v(intsem_id)structsembufsem_b;sem_b.sem_num=0;/*id*/sem_b.sem_op=1;/*Voperation*/sem_b.sem_flg=SEM_UNDO;/*Itstracksbefollow,toautomaticalfreeforit*/if(semop(sem_id,&sem_b,1)=-1)perror(Voperation);return-1;return0;4a/*producer.c*/#includeshm_com.h#inclu

5、desem_com.h#includeintignore_signal(void)signal(SIGINT,SIG_IGN);signal(SIGSTOP,SIG_IGN);signal(SIGQUIT,SIG_IGN);return0;intmain()void*shared_memory=NULL;structshm_buff*shm_buff_inst;charbufferBUFSIZ;intshmid,semid;ignore_signal();/*防止程序非正常退出*/semid=semget(ftok(.,a),1,0666IIPC_CREAT);/*创建一个信号量刃init_s

6、em(semid,1);/*初始值为1*/*创建共享内存*/shmid=shmget(ftok(.,b),sizeof(structshm_buff),0666IIPC_CREAT);if(shmid=-1)perror(shmgetfailed);del_sem(semid);exit；/*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；printf(Memoryattachedat%Xn,(int)sh

7、ared_memory);/*获得共享内存的映射地址*/shm_buff_inst=(structshm_buff*)shared_memory;dosem_p(semid);printf(Entersometexttothesharedmemory(enterquittoexit):);/*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(s

8、hm_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；exit(0);5、/*customer.c*/#includeshm_com.h#includesem_com.hintmain()void*shared_memory=NULL;structshm_buff*shm_buff_inst;intshmid,semid;/*获得信号量*/semid=semget(ftok(.,a),1,0666);i

9、f(semid=-1)perror(Producerisntexist);exit；/*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;dosem_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);wh