控制消息队列权限

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <errno.h>
#include <string.h>
#include <sys/shm.h>

typedef struct
{
long int nType;
char szText[256];
}MSG;

int main(int argc, char** argv) {
    key_t IKey1;
    int n,nMsgId;
    MSG msg;
    struct msqid_ds qds;
    if((IKey1 = ftok("/etc/profile",1)) == -1)
    {
        perror("ftok");
        exit(1);
    }
    
    if((nMsgId = msgget(IKey1,0)) == -1)
    {
        perror("msgget");
        exit(2);
    }
      
    memset(&qds,0x00,sizeof(struct msqid_ds));
    if(msgctl(nMsgId,IPC_STAT,&qds));
    {
        //perror("msgctl IPC_STAT");
        printf("error happen\n");
        exit(3);
    }
    printf("msg_perm.mode=%d\n",qds.msg_perm.mode);
    
    qds.msg_perm.mode &=(~0222);
    
    if(msgctl(nMsgId,IPC_SET,&qds)<0)
    {
         perror("msgctl IPC_SET");
        exit(3);
    }
    
    memset(&msg,0x00,sizeof(MSG));
    msg.nType=2;
    memcpy(msg.szText,"12345",5);
    
    if((n = msgsnd(nMsgId,(const void*)&msg,5,0))<0)
    {
        perror("msgsnd");
    }
    
    if(msgctl(nMsgId,IPC_RMID,NULL)<0){
        perror("msgctl IPC_RMID");
        exit(5);
    }
  
    return 0;
}