shared memory 에 저장된 data 를 읽어오고 싶습니다.

#include<stdio.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/shm.h>
#include<string.h>
#include<sys/stat.h>
#define MAX_BUF 256
#define MAX 30 
 
 
 
 
 
int shared(int argc ,char *argv[])
{
 
 
 
FILE *in ;
char s[MAX];
char *ptr;
char *ptr_p;
char *ptr_size;
char *ptr_p2;
struct shmid_ds shmid_buffer;
long  size;
int key,shmid, len,rtrn;
char *shared_memory,*sh;
char *sh_array;
char *c1 = "USR_SHMKEY=";
char *c2 = "USR_SHMSIZE=";
char* shared_stuff;
char filename[40]="";
char *string;
int segment_size;
char buf[MAX_BUF];
 
strcat(filename,argv[2]);
strcat(filename,".conf");
 
 
if((chdir("/config"))==-1)
{
 
fputs("cannnot move to this directory\n",stderr);
exit(1);
 
}
 
 
if((in=fopen(filename,"r")) == NULL)
{
 
	fputs("cannot open input file \n",stderr);
	exit(1);
}
while(fgets(s,MAX,in)!=NULL)
{
	ptr=strstr(s,c1);
	ptr_size=strstr(s,c2);
 
	if(ptr)
	{
		ptr_p=strtok(ptr,"");
       		 key = atoi(ptr_p+11);
		printf("key is : %d\n",key);
	}
 
 
	if(ptr_size)
	{
 
		ptr_p2=strtok(ptr_size,"");
       		 size = atol(ptr_p2+12);
		printf("SIZE is : %d\n",size);
	}
}
 
//fcloseall();
 
//if ((shmid = shmget((key_t)key,(size_t)size,IPC_CREAT|0666)) == -1)
if ((shmid = shmget((key_t)key,(size_t)size,S_IRUSR|S_IWUSR)) == -1)
{
	perror("shmget failed");
	exit(1);
}
 
shared_memory=(char *)shmat(shmid, NULL,SHM_RDONLY);
if(shared_memory ==(char *)-1){
 
	perror("shmat failed");
	exit(1);
}
printf("Memory is atatched at %X\n",(int)shared_memory);
 
 
memcpy(buf,shared_memory,sizeof(&shared_memory));
printf("Received from shared memory is %s\n",(char*)shared_memory);
printf("Received from shared memory is %s\n",buf);
 
shmctl(shmid,IPC_STAT,&shmid_buffer);
segment_size = shmid_buffer.shm_segsz;
printf("segment size : %d\n",segment_size);
shmdt(shared_memory);
return 0;
}