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£¬ÄúºÃ£¡
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=shmget(SHM_KEY,SHM_SIZE,IPC_CREAT|0660)==-1)
{
perror("shmget");
exit(-1);
}
printf("shmid: %d\n",shmid);
if(shmaddr1=shmat(shmid,0,0)==-1)
{
perror("shmat 1");
exit(-1);
}
printf("shaddr1:0x%.8x\n",shmaddr1);
if(shmaddr2=shmat(shmid,0,0)==-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) ?
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¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡airsupply
¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡airsupply@freebsdchina.org
¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡2004-02-07
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