linux_c语言实现父子进程共享内存

具体代码实现部分：

#include<stdio.h>
#include<sys/shm.h>
#include<sys/ipc.h>
#include<sys/types.h>

extern int etext,edata,end;
int main(int argc,char *argv[ ])
{
int shmid;
int proj_id;
key_t key;
int shm_size;
char *shm_addr,*addr;
pid_t pid;
if(argc!=3){
printf("usage:%s shared_memory_size info\n",argv[0]);
return 1;
}
shm_size=atoi(argv[1]);
proj_id=2;
key=ftok("./",proj_id);
if(key==-1){
perror("cannot generate the ipc key");
return 1;
}

shmid=shmget(key,shm_size,IPC_CREAT | 0660);
if(shmid==-1)
{
perror("cannot create a shared memory segment ");
return 1;
}

addr=(char*)shmat(shmid,NULL,0);
shm_addr=addr;
if(shm_addr==(char*)(-1)){
perror("cannot attach the shared memory to process");
return 1;
}
printf("\n");
printf("==========address information==========\n");
printf("etext address:%x\n",&etext);
printf("edata address:%x\n",&edata);
printf("end address :%x\n",&end);
printf("shared memory segment address:%x\n",shm_addr);
printf("=======================================\n");

strcpy(shm_addr,argv[2]);
printf("the input string is:%s\n",argv[2]);
printf("before fork,int shared memory segment the string is:%s\n",shm_addr);

pid=fork();
if(pid==-1){
perror("cannot creat new process");
return 1;
}else if(pid==0){
printf("in child process,the string is:%s\n",shm_addr);
printf("modify the content in shared memory\n");

*shm_addr +=1;
_exit(0);
}else{
wait(NULL);

printf("after fork,int shared memory segment the string is: %s\n",shm_addr);
if(shmdt(shm_addr)==-1){
perror("cannot release the memory");
return 1;
}

if(shmctl(shmid,IPC_RMID,NULL)==-1){
perror("cannot delete existing shared memory segment");
return 1;
}
}
return 0;
}
然后就是编译运行了：

#gcc -o  share_memory  share_memory.c

#./share_memory 1024 message_to_shared_memory