#include #define BUFFER_SIZE 2048

int main()

{

pid_t pid;

int shmid;

char *shm_addr;

char flag[] = \"WROTE\";

char *buff;

/* 创建共享内存 */

if ((shmid = shmget(IPC_PRIVATE, BUFFER_SIZE, 0666)) < 0)

{

perror(\"shmget\");

exit(1);

}

else

{

printf(\"Create shared-memory: %d\\n\",shmid);

}

/* 显示共享内存情况 */

system(\"ipcs -m\");

pid = fork();

if (pid == -1)

{

perror(\"fork\");

exit(1);

}

else if (pid == 0) /* 子进程处理 */

{

/* 映射共享内存 */

if ((shm_addr = shmat(shmid, 0, 0)) == (void*)-1)

{

perror(\"Child: shmat\");

exit(1);

}

else

{

printf(\"Child: Attach shared-memory: %p\\n\", shm_addr);

}

system(\"ipcs -m\");

/* 通过检查在共享内存的头部是否有标志字符串“WROTE”来确认父进程已经向共享内存写入有效数据 */

while (strncmp(shm_addr, flag, strlen(flag)))

{

printf(\"Child: Wait for enable data...\\n\");

sleep(5);

}

/* 获取共享内存的有效数据并显示 */

strcpy(buff, shm_addr + strlen(flag));

printf(\"Child: Shared-memory :%s\\n\", buff);

/* 解除共享内存映射 */

if ((shmdt(shm_addr)) < 0)

{

perror(\"shmdt\");

exit(1);

}

else

{

printf(\"Child: Deattach shared-memory\\n\");

}

system(\"ipcs -m\");

/* 删除共享内存 */

if (shmctl(shmid, IPC_RMID, NULL) == -1)

{

perror(\"Child: shmctl(IPC_RMID)\\n\");

exit(1);

}

else

{

printf(\"Delete shared-memory\\n\");

}

system(\"ipcs -m\");

}

else /* 父进程处理 */

{

/* 映射共享内存 */

if ((shm_addr = shmat(shmid, 0, 0)) == (void*)-1)

{

perror(\"Parent: shmat\");

exit(1);

}

else

{

printf(\"Parent: Attach shared-memory: %p\\n\", shm_addr);

}

sleep(1);

printf(\"\\nInput some string:\\n\");

fgets(buff, BUFFER_SIZE, stdin);

strncpy(shm_addr + strlen(flag), buff, strlen(buff));

strncpy(shm_addr, flag, strlen(flag));

/* 解除共享内存映射 */

if ((shmdt(shm_addr)) < 0)

{

perror(\"Parent: shmdt\");

exit(1);

}

else

{

printf(\"Parent: Deattach shared-memory\\n\");

}

system(\"ipcs -m\");

waitpid(pid, NULL, 0);

printf(\"Finished\\n\");

}

exit(0);

}