busybox/util-linux/rdate.c
Denys Vlasenko 54e9585e10 trivial code shrink
function                                             old     new   delta
rdate_main                                           246     251      +5
show_entry                                           291     287      -4
daytime_stream                                        44      39      -5
packed_usage                                       30176   30168      -8
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/3 up/down: 5/-17)             Total: -12 bytes
   text	   data	    bss	    dec	    hex	filename
 929453	    932	  17684	 948069	  e7765	busybox_old
 929411	    932	  17684	 948027	  e773b	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2015-02-18 13:47:46 +01:00

80 lines
2.0 KiB
C

/* vi: set sw=4 ts=4: */
/*
* The Rdate command will ask a time server for the RFC 868 time
* and optionally set the system time.
*
* by Sterling Huxley <sterling@europa.com>
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//usage:#define rdate_trivial_usage
//usage: "[-sp] HOST"
//usage:#define rdate_full_usage "\n\n"
//usage: "Get and possibly set system time from a remote HOST\n"
//usage: "\n -s Set system time (default)"
//usage: "\n -p Print time"
#include "libbb.h"
enum { RFC_868_BIAS = 2208988800UL };
static void socket_timeout(int sig UNUSED_PARAM)
{
bb_error_msg_and_die("timeout connecting to time server");
}
static time_t askremotedate(const char *host)
{
uint32_t nett;
int fd;
/* Add a timeout for dead or inaccessible servers */
alarm(10);
signal(SIGALRM, socket_timeout);
fd = create_and_connect_stream_or_die(host, bb_lookup_port("time", "tcp", 37));
if (safe_read(fd, &nett, 4) != 4) /* read time from server */
bb_error_msg_and_die("%s: %s", host, "short read");
if (ENABLE_FEATURE_CLEAN_UP)
close(fd);
/* Convert from network byte order to local byte order.
* RFC 868 time is the number of seconds
* since 00:00 (midnight) 1 January 1900 GMT
* the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
* Subtract the RFC 868 time to get Linux epoch.
*/
return ntohl(nett) - RFC_868_BIAS;
}
int rdate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int rdate_main(int argc UNUSED_PARAM, char **argv)
{
time_t remote_time;
unsigned flags;
opt_complementary = "-1";
flags = getopt32(argv, "sp");
remote_time = askremotedate(argv[optind]);
if (!(flags & 2)) { /* no -p (-s may be present) */
time_t current_time;
time(&current_time);
if (current_time == remote_time)
bb_error_msg("current time matches remote time");
else
if (stime(&remote_time) < 0)
bb_perror_msg_and_die("can't set time of day");
}
if (flags != 1) /* not lone -s */
printf("%s", ctime(&remote_time));
return EXIT_SUCCESS;
}