busybox/util-linux/hwclock.c

/* vi: set sw=4 ts=4: */
/*
 * Mini hwclock implementation for busybox
 *
 * Copyright (C) 2002 Robert Griebl <griebl@gmx.de>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/


#include <sys/ioctl.h>
#include <sys/utsname.h>
#include <ctype.h>
#include <fcntl.h>
#include <getopt.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <unistd.h>
#include "busybox.h"

/* Copied from linux/rtc.h to eliminate the kernel dependency */
struct linux_rtc_time {
	int tm_sec;
	int tm_min;
	int tm_hour;
	int tm_mday;
	int tm_mon;
	int tm_year;
	int tm_wday;
	int tm_yday;
	int tm_isdst;
};

#define RTC_SET_TIME   _IOW('p', 0x0a, struct linux_rtc_time) /* Set RTC time    */
#define RTC_RD_TIME    _IOR('p', 0x09, struct linux_rtc_time) /* Read RTC time   */

#if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS
# ifndef _GNU_SOURCE
#  define _GNU_SOURCE
# endif
#endif

static time_t read_rtc(int utc)
{
	int rtc;
	struct tm tm;
	char *oldtz = 0;
	time_t t = 0;

	if (( rtc = open ( "/dev/rtc", O_RDONLY )) < 0 ) {
		if (( rtc = open ( "/dev/misc/rtc", O_RDONLY )) < 0 )
			bb_perror_msg_and_die ( "cannot access RTC" );
	}
	memset ( &tm, 0, sizeof( struct tm ));
	if ( ioctl ( rtc, RTC_RD_TIME, &tm ) < 0 )
		bb_perror_msg_and_die ( "cannot read time from RTC" );
	tm.tm_isdst = -1; /* not known */

	close ( rtc );

	if ( utc ) {
		oldtz = getenv ( "TZ" );
		setenv ( "TZ", "UTC 0", 1 );
		tzset ( );
	}

	t = mktime ( &tm );

	if ( utc ) {
		if ( oldtz )
			setenv ( "TZ", oldtz, 1 );
		else
			unsetenv ( "TZ" );
		tzset ( );
	}
	return t;
}

static void write_rtc(time_t t, int utc)
{
	int rtc;
	struct tm tm;

	if (( rtc = open ( "/dev/rtc", O_WRONLY )) < 0 ) {
		if (( rtc = open ( "/dev/misc/rtc", O_WRONLY )) < 0 )
			bb_perror_msg_and_die ( "cannot access RTC" );
	}

	tm = *( utc ? gmtime ( &t ) : localtime ( &t ));
	tm.tm_isdst = 0;

	if ( ioctl ( rtc, RTC_SET_TIME, &tm ) < 0 )
		bb_perror_msg_and_die ( "cannot set the RTC time" );

	close ( rtc );
}

static int show_clock(int utc)
{
	struct tm *ptm;
	time_t t;
	RESERVE_CONFIG_BUFFER(buffer, 64);

	t = read_rtc ( utc );
	ptm = localtime ( &t );  /* Sets 'tzname[]' */

	safe_strncpy ( buffer, ctime ( &t ), 64);
	if ( buffer [0] )
		buffer [strlen ( buffer ) - 1] = 0;

	//printf ( "%s  %.6f seconds %s\n", buffer, 0.0, utc ? "" : ( ptm-> tm_isdst ? tzname [1] : tzname [0] ));
	printf ( "%s  %.6f seconds\n", buffer, 0.0 );
	RELEASE_CONFIG_BUFFER(buffer);

	return 0;
}

static int to_sys_clock(int utc)
{
	struct timeval tv = { 0, 0 };
	const struct timezone tz = { timezone/60 - 60*daylight, 0 };

	tv.tv_sec = read_rtc ( utc );

	if ( settimeofday ( &tv, &tz ))
		bb_perror_msg_and_die ( "settimeofday() failed" );

	return 0;
}

static int from_sys_clock(int utc)
{
	struct timeval tv = { 0, 0 };
	struct timezone tz = { 0, 0 };

	if ( gettimeofday ( &tv, &tz ))
		bb_perror_msg_and_die ( "gettimeofday() failed" );

	write_rtc ( tv.tv_sec, utc );
	return 0;
}

#ifdef CONFIG_FEATURE_HWCLOCK_ADJTIME_FHS
# define ADJTIME_PATH "/var/lib/hwclock/adjtime"
#else
# define ADJTIME_PATH "/etc/adjtime"
#endif
static int check_utc(void)
{
	int utc = 0;
	FILE *f = fopen ( ADJTIME_PATH, "r" );

	if ( f ) {
		RESERVE_CONFIG_BUFFER(buffer, 128);

		while ( fgets ( buffer, sizeof( buffer ), f )) {
			int len = strlen ( buffer );

			while ( len && isspace ( buffer [len - 1] ))
				len--;

			buffer [len] = 0;

			if ( strncmp ( buffer, "UTC", 3 ) == 0 ) {
				utc = 1;
				break;
			}
		}
		fclose ( f );
		RELEASE_CONFIG_BUFFER(buffer);
	}
	return utc;
}

#define HWCLOCK_OPT_LOCALTIME	0x01
#define HWCLOCK_OPT_UTC			0x02
#define HWCLOCK_OPT_SHOW		0x04
#define HWCLOCK_OPT_HCTOSYS		0x08
#define HWCLOCK_OPT_SYSTOHC		0x10

int hwclock_main ( int argc, char **argv )
{
	unsigned opt;
	int utc;

#if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS
static const struct option hwclock_long_options[] = {
		{ "localtime", 0, 0, 'l' },
		{ "utc",       0, 0, 'u' },
		{ "show",      0, 0, 'r' },
		{ "hctosys",   0, 0, 's' },
		{ "systohc",   0, 0, 'w' },
		{ 0,           0, 0, 0 }
	};
	applet_long_options = hwclock_long_options;
#endif

	opt_complementary = "?:r--ws:w--rs:s--wr:l--u:u--l";
	opt = getopt32(argc, argv, "lursw");

	/* If -u or -l wasn't given check if we are using utc */
	if (opt & (HWCLOCK_OPT_UTC | HWCLOCK_OPT_LOCALTIME))
		utc = opt & HWCLOCK_OPT_UTC;
	else
		utc = check_utc();

	if (opt & HWCLOCK_OPT_HCTOSYS) {
		return to_sys_clock ( utc );
	}
	else if (opt & HWCLOCK_OPT_SYSTOHC) {
		return from_sys_clock ( utc );
	} else {
		/* default HWCLOCK_OPT_SHOW */
		return show_clock ( utc );
	}
}