os_kernel_lab/related_info/lab7/ipc/shmem/shmem_client.c

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
 
#define SHMSZ     1024
 
main()
{
	int shmid;
	key_t key;
	char *shm, *s;
 
	/*
	* We need to get the segment named
	* "1234", created by the server.
	*/
	key = 1234;
 
	/*
	* Locate the segment.
	*/
	if ((shmid = shmget(key, SHMSZ, 0666)) < 0) {
		perror("shmget");
		return 1;
	}
 
	/*
	* Now we attach the segment to our data space.
	*/
	if ((shm = shmat(shmid, NULL, 0)) == (char *) -1) {
		perror("shmat");
		return 1;
	}
 
	/*
	* Zero out memory segment
	*/
	memset(shm,0,SHMSZ);
	s = shm;
 
	/*
	* Client writes user input character to memory
	* for server to read.
	*/
	for(;;){
		char tmp = getchar();
		// Eat the enter key
		getchar();
 
		if(tmp == 'q'){
			*shm = 'q';
			break;
		}
		*shm = tmp;
	}
 
	if(shmdt(shm) != 0)
		fprintf(stderr, "Could not close memory segment.\n");
 
	return 0;
}