rtime.c

操作系统SunOS 4.1.3版本的源码

#if !defined(lint) && defined(SCCSIDS)
static char sccsid[] = "@(#)rtime.c 1.1 92/07/30 Copyr 1987 Sun Micro";
#endif
/*
 * rtime - get time from remote machine
 *
 * Copyright (C) 1986, Sun Microsystems, Inc.
 *
 * gets time, obtaining value from host
 * on the udp/time socket.  Since timeserver returns
 * with time of day in seconds since Jan 1, 1900,  must
 * subtract seconds before Jan 1, 1970 to get
 * what unix uses.
 */
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/errno.h>
#include <netinet/in.h>
#include <stdio.h>

#define	NYEARS	(1970 - 1900)
#define	TOFFSET (60*60*24*(365*NYEARS + (NYEARS/4)))
extern errno;

static void do_close();

rtime(addrp, timep, timeout)
	struct sockaddr_in *addrp;
	struct timeval *timep;
	struct timeval *timeout;
{
	int s;
	fd_set readfds;
	int res;
	unsigned long thetime;
	struct sockaddr_in from;
	int fromlen;
	int type;

	if (timeout == NULL) {
		type = SOCK_STREAM;
	} else {
		type = SOCK_DGRAM;
	}
	s = socket(AF_INET, type, 0);
	if (s < 0) {
		return (-1);
	}
	addrp->sin_family = AF_INET;
	addrp->sin_port = htons(IPPORT_TIMESERVER);
	if (type == SOCK_DGRAM) {
		res = sendto(s, (char *)&thetime, sizeof (thetime), 0,
		    (struct sockaddr *)addrp, sizeof (*addrp));
		if (res < 0) {
			do_close(s);
			return (-1);
		}
		do {
			FD_ZERO(&readfds);
			FD_SET(s, &readfds);
			res = select(_rpc_dtablesize(), &readfds, (int *)NULL,
			    (int *)NULL, timeout);
		} while (res < 0 && errno == EINTR);
		if (res <= 0) {
			if (res == 0) {
				errno = ETIMEDOUT;
			}
			do_close(s);
			return (-1);
		}
		fromlen = sizeof (from);
		res = recvfrom(s, (char *)&thetime, sizeof (thetime), 0,
		    (struct sockaddr *)&from, &fromlen);
		do_close(s);
		if (res < 0) {
			return (-1);
		}
	} else {
		if (connect(s, (struct sockaddr *)addrp, sizeof (*addrp)) < 0) {
			do_close(s);
			return (-1);
		}
		res = read(s, (char *)&thetime, sizeof (thetime));
		do_close(s);
		if (res < 0) {
			return (-1);
		}
	}
	if (res != sizeof (thetime)) {
		errno = EIO;
		return (-1);
	}
	thetime = ntohl(thetime);
	timep->tv_sec = thetime - TOFFSET;
	timep->tv_usec = 0;
	return (0);
}

static void
do_close(s)
	int s;
{
	int save;

	save = errno;
	(void) close(s);
	errno = save;
}