msg_queue.c

关于进程间通信的代码集锦

#include <sys/types.h>
#include <sys/msg.h>
#include <unistd.h>

void msg_stat(int,struct msqid_ds);
int main(int argc,char** argv)
{
	int gflags,sflags,rflags;
	key_t key;
	int msgid;
	int reval;
	struct msgsbuf{
		int mtype;
		char mtext[1];
	}msg_sbuf;
	struct msgmbuf{
		int mtype;
		char mtext[10];
	}msg_rbuf;
	struct msqid_ds msg_ginfo,msg_sinfo;
	char* msgpath="/unix/msgqueue";
	key=ftok(msgpath,'a');
	gflags=IPC_CREAT|IPC_EXCL;
	msgid=msgget(key,gflags|00666);
	if(msgid==-1)
	{
		printf("msg create error.\n");
		return 0;
	}
	msg_stat(msgid,msg_ginfo);
	sflags=IPC_NOWAIT;
	msg_sbuf.mtype=10;
	msg_sbuf.mtext[0]='a';
	reval=msgsnd(msgid,&msg_sbuf,sizeof(msg_sbuf.mtext),sflags);
	if(reval==-1)
	{
		printf("message send error\n");	
	}
	msg_stat(msgid,msg_ginfo);
	rflags=IPC_NOWAIT|MSG_NOERROR;
	reval=msgrcv(msgid,&msg_rbuf,4,10,rflags);
	if(reval==-1)
	{
		printf("read msg error\n");
	}
	else
	{
		printf("read from msg queue %d bytes\n",reval);
	}
	msg_stat(msgid,msg_ginfo);
	msg_sinfo.msg_perm.uid=8;
	msg_sinfo.msg_perm.gid=8;
	msg_sinfo.msg_qbytes=16388;
	
	reval=msgctl(msgid,IPC_SET,&msg_sinfo);
	if(reval==-1)
	{
		printf("msg set info error\n");
		return 0;
	}
	msg_stat(msgid,msg_ginfo);
	reval=msgctl(msgid,IPC_RMID,NULL);
	if(reval==-1)
	{
		printf("unlink msg queue error\n");
		return 0;
	}
	return 0;
}
void msg_stat(int msgid,struct msqid_ds msg_info)
{
	int reval;
	sleep(1);
	reval=msgctl(msgid,IPC_STAT,&msg_info);
	if(reval==-1)
	{
		printf("get msg info error\n");
		return 0;
	}
	printf("\n");
	printf("current number of bytes on queue is %d\n",msg_info.msg_cbytes);
	printf("number of messages in queue is %d\n",msg_info.msg_qnum);
	printf("max number of bytes on queue is %d\n",msg_info.msg_qbytes);
	printf("pid of last msgsnd is %d\n",msg_info.msg_lspid);
	printf("pid of last msgrcv is %d\n",msg_info.msg_lrpid);
	printf("last msgsnd time is %s",ctime(&(msg_info.msg_stime)));
	printf("last msgrcv time is %s",ctime(&(msg_info.msg_rtime)));
	printf("last change time is %s",ctime(&(msg_info.msg_ctime)));
	printf("msg uid is %d\n",msg_info.msg_perm.uid);
	printf("msg gid is %d\n",msg_info.msg_perm.gid);
}