嵌入式共享內(nèi)存作業(yè)

1、1 / 6共享內(nèi)存作業(yè)內(nèi)容：共享內(nèi)存實(shí)驗(yàn)中，P275 代碼不能正確運(yùn)行。請(qǐng)修改代碼，并分析原因 代碼：1、/* sem_com.h */#ifndefSEM_COM_H#defi neSEM_COM_H#i nclude #i nclude union sem unint val;struct semid_ds *buf; un sig ned short *array;int ini t_sem(i nt, in t); int del_sem(i nt);int sem_p(i nt);int sem_v(i nt);#en dif /* SEM_COM_H */2、/* shm_com.

2、h */#ifndefSHM_COM_H#defi neSHM_COM_H#i nclude #i nclude #i nclude #include #i nclude #i nclude #i nclude #defi ne SHM_BUFF_SZ 20482 / 6struct shm_buffint pid;char bufferSHM_BUFF_SZ; ;#endif /* SHM_COM_H */ 3、/* sem_com.c */#include sem_com.hint init_sem(int sem_id, int init_value)union semun sem_un

3、ion; sem_union.val = init_value;if (semctl(sem_id, 0, SETVAL, sem_union) = -1)perror(Initialize semaphore); return -1;return 0;int del_sem(int sem_id)union semun sem_union;if (semctl(sem_id, 0, IPC_RMID, sem_union) = -1)perror(Delete semaphore); return -1;int sem_p(int sem_id)struct sembuf sem_b; se

4、m_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:first struct*/ perror(P operation); return-1;return 0;int sem_v(int sem_id)struct sembuf sem_b;sem_b.sem_num = 0; /* id */ sem_b.sem_op = 1; /* V operation */sem_b.sem_flg =

5、 SEM_UNDO; /*Its tracks be follow, to automatical free for it*/if (semop(sem_id, &sem_b, 1) = -1)perror(V operation); return -1;return 0;3 / 64、/* producer.c */#include shm_com.h#include sem_com.h#include int ignore_signal(void)signal(SIGINT, SIG_IGN); signal(SIGSTOP, SIG_IGN); signal(SIGQUIT,SI

6、G_IGN); return 0;int main()void *shared_memory = NULL; struct shm_buff *shm_buff_inst; charbufferBUFSIZ;int shmid, semid;ignore_signal(); /* 防止程序非正常退出 */semid = semget(ftok(., a), 1, 0666|IPC_CREAT); /* 創(chuàng)建一個(gè)信號(hào)量 */init_sem(semid, 1);/* 初始值為 1 */* 創(chuàng)建共享內(nèi)存 */shmid = shmget(ftok(., b), sizeof(struct shm_

7、buff), 0666|IPC_CREAT);if (shmid = -1)perror(shmget failed);del_sem(semid);exit(1);/* 將共享內(nèi)存地址映射到當(dāng)前進(jìn)程地址空間 */ shared_memory = shmat(shmid,(void*)0, 0);if (shared_memory = (void*)-1)perror(shmat);del_sem(semid);exit(1);printf(Memory attached at %Xn, (int)shared_memory);/* 獲得共享內(nèi)存的映射地址 */shm_buff_inst =

8、(struct shm_buff *)shared_memory;dosem_p(semid);printf(Enter some text to the shared memory(enter quit to exit):);/* 向共享內(nèi)存寫入數(shù)據(jù) */4 / 6if (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-buf

9、fer, quit, 4) != 0);/* 刪除信號(hào)量 */ del_sem(semid);/* 刪除共享內(nèi)存到當(dāng)前進(jìn)程地址空間中的映射 */ if (shmdt(shared_memory) = 1)perror(shmdt); exit(1);exit(0);5、/* customer.c */ #include shm_com.h#include sem_com.h int main()void *shared_memory = NULL; struct shm_buff *shm_buff_inst; int shmid, semid;/* 獲得信號(hào)量 */semid = semge

10、t(ftok(., a), 1, 0666); if (semid = -1)perror(Producer isnt exist); exit(1);/* 獲得共享內(nèi)存 */shmid = shmget(ftok(., b), sizeof(struct shm_buff), 0666|IPC_CREAT); if(shmid = -1)perror(shmget);exit(1);/* 將共享內(nèi)存地址映射到當(dāng)前進(jìn)程地址空間 */ shared_memory = shmat(shmid,(void*)0, 0);if (shared_memory = (void*)-1)perror(shm

11、at); exit(1);printf(Memory attached at %Xn, (int)shared_memory);/* 獲得共享內(nèi)存的映射地址 */shm_buff_inst = (struct shm_buff *)shared_memory;dosem_p(semid); printf(Shared memory was written by process %d :%s,shm_buff_inst-pid, shm_buff_inst-buffer);if (strncmp(shm_buff_inst-buffer, quit, 4) = 0)5 / 6break;shm_buff_inst-pid = 0; memset(shm_buff_inst-buffer, 0, SHM_BUFF_SZ);sem_v(semid); wh