kernel-ark/drivers/rtc/rtc-lib.c
Jan Altenberg 73442daf2e rtc_time_to_tm: fix signed/unsigned arithmetic
commit 945185a69d ("rtc: rtc_time_to_tm: use
unsigned arithmetic") changed the some types in rtc_time_to_tm() to
unsigned:

 void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
 {
-       register int days, month, year;
+       unsigned int days, month, year;

This doesn't work for all cases, because days is checked for < 0 later
on:

if (days < 0) {
	year -= 1;
	days += 365 + LEAP_YEAR(year);
}

I think the correct fix would be to keep days signed and do an appropriate
cast later on.

Signed-off-by: Jan Altenberg <jan.altenberg@linutronix.de>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Cc: Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-09-02 19:21:40 -07:00

122 lines
2.9 KiB
C

/*
* rtc and date/time utility functions
*
* Copyright (C) 2005-06 Tower Technologies
* Author: Alessandro Zummo <a.zummo@towertech.it>
*
* based on arch/arm/common/rtctime.c and other bits
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/rtc.h>
static const unsigned char rtc_days_in_month[] = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
static const unsigned short rtc_ydays[2][13] = {
/* Normal years */
{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
/* Leap years */
{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};
#define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
#define LEAP_YEAR(year) ((!(year % 4) && (year % 100)) || !(year % 400))
/*
* The number of days in the month.
*/
int rtc_month_days(unsigned int month, unsigned int year)
{
return rtc_days_in_month[month] + (LEAP_YEAR(year) && month == 1);
}
EXPORT_SYMBOL(rtc_month_days);
/*
* The number of days since January 1. (0 to 365)
*/
int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
{
return rtc_ydays[LEAP_YEAR(year)][month] + day-1;
}
EXPORT_SYMBOL(rtc_year_days);
/*
* Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
*/
void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
{
unsigned int month, year;
int days;
days = time / 86400;
time -= (unsigned int) days * 86400;
/* day of the week, 1970-01-01 was a Thursday */
tm->tm_wday = (days + 4) % 7;
year = 1970 + days / 365;
days -= (year - 1970) * 365
+ LEAPS_THRU_END_OF(year - 1)
- LEAPS_THRU_END_OF(1970 - 1);
if (days < 0) {
year -= 1;
days += 365 + LEAP_YEAR(year);
}
tm->tm_year = year - 1900;
tm->tm_yday = days + 1;
for (month = 0; month < 11; month++) {
int newdays;
newdays = days - rtc_month_days(month, year);
if (newdays < 0)
break;
days = newdays;
}
tm->tm_mon = month;
tm->tm_mday = days + 1;
tm->tm_hour = time / 3600;
time -= tm->tm_hour * 3600;
tm->tm_min = time / 60;
tm->tm_sec = time - tm->tm_min * 60;
}
EXPORT_SYMBOL(rtc_time_to_tm);
/*
* Does the rtc_time represent a valid date/time?
*/
int rtc_valid_tm(struct rtc_time *tm)
{
if (tm->tm_year < 70
|| ((unsigned)tm->tm_mon) >= 12
|| tm->tm_mday < 1
|| tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
|| ((unsigned)tm->tm_hour) >= 24
|| ((unsigned)tm->tm_min) >= 60
|| ((unsigned)tm->tm_sec) >= 60)
return -EINVAL;
return 0;
}
EXPORT_SYMBOL(rtc_valid_tm);
/*
* Convert Gregorian date to seconds since 01-01-1970 00:00:00.
*/
int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time)
{
*time = mktime(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
return 0;
}
EXPORT_SYMBOL(rtc_tm_to_time);
MODULE_LICENSE("GPL");