Linux嵌入式-共享內(nèi)存作業(yè)

1、精選文檔共享內(nèi)存作業(yè)內(nèi)容：共享內(nèi)存實驗中，P275代碼不能正確運行。請修改代碼，并分析原因代碼：1、/* sem_com.h */#ifndef SEM_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, i nt);int del_sem(i nt);int sem_p(i nt);int sem_v(i nt);#endif /* SEM_COM_H */2 、/* shm_com.h */

2、#ifndef SHM_COM_H#define SHM_COM_H#include #include #include #include #include #include #include #define SHM_BUFF_SZ 2048struct shm_buffint pid;char bufferSHM_BUFF_SZ;#endif /* SHM_COM_H */3 、/* sem_com.c */ #include sem_com.h int init_sem(int sem_id, int init_value)union semun sem_union; sem_union.

3、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;sem_b.sem_num = 0;

4、 /*id*/sem_b.sem_op = -1; /* P operation*/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 = SEM_UNDO; /*Its tracks

5、 be follow, to automatical free for it*/if (semop(sem_id, &sem_b, 1) = -1)perror(V operation);return -1;return 0;4 、/* 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, SIG_IGN); return 0;int main()voi

6、d *shared_memory = NULL;struct shm_buff *shm_buff_inst;char bufferBUFSIZ;int shmid, semid;創(chuàng)建一個信號量shm_buff),ignore_signal(); /* 防止程序非正常退出 */semid = semget(ftok(., a),1, 0666|IPC_CREAT); /*/init_sem(semid, 1);/* 初始值為 1 */* 創(chuàng)建共享內(nèi)存 */shmid = shmget(ftok(., b), sizeof(struct 0666|IPC_CREAT);if (shmid = -

7、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 = (struct shm_buff *)shared_memory;dos

8、em_p(semid);toprintf(Enter some text to the shared memory(enter quitexit):);/* 向共享內(nèi)存寫入數(shù)據(jù) */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);/* 刪除信號量 */del_sem(sem

9、id);/* 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.hint main()void *shared_memory = NULL;struct shm_buff *shm_buff_inst;int shmid, semid;/* 獲得信號量 */semid = semget(ftok(., a),1, 0666);if (semid = -1)perror(Prod

10、ucer isnt exist);exit(1);/* 獲得共享內(nèi)存 */shm_buff),shmid = shmget(ftok(., b), sizeof(struct 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(shmat);exit(1);printf(Memory attached at %Xn, (int)sha

11、red_memory);/* 獲得共享內(nèi)存的映射地址 */shm_buff_inst = (struct shm_buff *)shared_memory;dosem_p(semid);:%s,printf(Shared memory was written by process %d 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