catgetmsg.c

UNIX环境下利用高级IO技术实现非阻塞的输入/输出

#include	<stropts.h>
#include	"ourhdr.h"

#define	BUFFSIZE	8192

int
main(void)
{
	int				n, flag;
	char			ctlbuf[BUFFSIZE], datbuf[BUFFSIZE];
	struct strbuf	ctl, dat;

	ctl.buf = ctlbuf;
	ctl.maxlen = BUFFSIZE;
	dat.buf = datbuf;
	dat.maxlen = BUFFSIZE;
	for ( ; ; ) {
		flag = 0;		/* return any message */
		if ( (n = getmsg(STDIN_FILENO, &ctl, &dat, &flag)) < 0)
			err_sys("getmsg error");
		fprintf(stderr, "flag = %d, ctl.len = %d, dat.len = %d\n",
						flag, ctl.len, dat.len);
		if (dat.len == 0)
			exit(0);
		else if (dat.len > 0)
			if (write(STDOUT_FILENO, dat.buf, dat.len) != dat.len)
				err_sys("write error");
	}
}