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Date:      Sat, 7 Feb 2004 23:37:31 +0800
From:      "airsupply" <airsupply@freebsdchina.org>
To:        freebsd-hackers@freebsd.org <freebsd-hackers@freebsd.org>
Subject:   shmat  help
Message-ID:  <20040207153833.66AC843D1D@mx1.FreeBSD.org>
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freebsd-hackers=A3=AC=C4=FA=BA=C3=A3=A1

=09                  
i am test shmat under freebsd 4.8 release(without undate),but a=
 piece of simple code wont work.
code like this:
#include<stdio.h>
#include<machine/param.h>
#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/shm.h>
#include <unistd.h>

#define SHM_KEY 100
#define SHM_SIZE 1024
int main(int argc,char *argv[])
{
        int shmid;
        void *shmaddr1,*shmaddr2,*shmaddr3;
        if(shmid=3Dshmget(SHM_KEY,SHM_SIZE,IPC_CREAT|0660)=3D=3D-1)
        {
                perror("shmget");
                exit(-1);
        }

        printf("shmid: %d\n",shmid);
        if(shmaddr1=3Dshmat(shmid,0,0)=3D=3D-1)
        {
                perror("shmat 1");
                exit(-1);
        }
        printf("shaddr1:0x%.8x\n",shmaddr1);

        if(shmaddr2=3Dshmat(shmid,0,0)=3D=3D-1)
        {
                perror("shmat 2");
                exit(-1);
        }
        printf("shaddr2:0x%.8x\n",shmaddr2);
        while(1);
        return 0;
}

then i get error like this:

shmid: 0
shmat 1: Invalid argument
then i use ipcs,find that the shmid is not 0,but an integer=
 number.
-bash-2.05b$ ipcs
Message Queues:
T     ID     KEY        MODE       OWNER    GROUP

Shared Memory:
T     ID     KEY        MODE       OWNER    GROUP
m  65536        100 --rw-rw-rw-     airs    wheel

Semaphores:
T     ID     KEY        MODE       OWNER    GROUP



who can help me? who i can't use the shmid at shmat(shmid,0,0) ? =
 


=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=D6=C2
=C0=F1=A3=A1
 =09=09=09=09

=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1airsupply
=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1airsupply@freebsdchina.org
=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A12004-02-07

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