diff options
Diffstat (limited to 'fs/fat/misc.c')
| -rw-r--r-- | fs/fat/misc.c | 148 |
1 files changed, 107 insertions, 41 deletions
diff --git a/fs/fat/misc.c b/fs/fat/misc.c index 91ad9be18ff9..a191e79e66a9 100644 --- a/fs/fat/misc.c +++ b/fs/fat/misc.c @@ -135,65 +135,131 @@ int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster) extern struct timezone sys_tz; +/* + * The epoch of FAT timestamp is 1980. + * : bits : value + * date: 0 - 4: day (1 - 31) + * date: 5 - 8: month (1 - 12) + * date: 9 - 15: year (0 - 127) from 1980 + * time: 0 - 4: sec (0 - 29) 2sec counts + * time: 5 - 10: min (0 - 59) + * time: 11 - 15: hour (0 - 23) + */ +#define SECS_PER_MIN 60 +#define SECS_PER_HOUR (60 * 60) +#define SECS_PER_DAY (SECS_PER_HOUR * 24) +#define UNIX_SECS_1980 315532800L +#if BITS_PER_LONG == 64 +#define UNIX_SECS_2108 4354819200L +#endif +/* days between 1.1.70 and 1.1.80 (2 leap days) */ +#define DAYS_DELTA (365 * 10 + 2) +/* 120 (2100 - 1980) isn't leap year */ +#define YEAR_2100 120 +#define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100) + /* Linear day numbers of the respective 1sts in non-leap years. */ -static int day_n[] = { - /* Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec */ - 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0, 0 +static time_t days_in_year[] = { + /* Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec */ + 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0, }; -/* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */ -int date_dos2unix(unsigned short time, unsigned short date, int tz_utc) +/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */ +void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts, + __le16 __time, __le16 __date, u8 time_cs) { - int month, year, secs; + u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date); + time_t second, day, leap_day, month, year; - /* - * first subtract and mask after that... Otherwise, if - * date == 0, bad things happen - */ - month = ((date >> 5) - 1) & 15; - year = date >> 9; - secs = (time & 31)*2+60*((time >> 5) & 63)+(time >> 11)*3600+86400* - ((date & 31)-1+day_n[month]+(year/4)+year*365-((year & 3) == 0 && - month < 2 ? 1 : 0)+3653); - /* days since 1.1.70 plus 80's leap day */ - if (!tz_utc) - secs += sys_tz.tz_minuteswest*60; - return secs; + year = date >> 9; + month = max(1, (date >> 5) & 0xf); + day = max(1, date & 0x1f) - 1; + + leap_day = (year + 3) / 4; + if (year > YEAR_2100) /* 2100 isn't leap year */ + leap_day--; + if (IS_LEAP_YEAR(year) && month > 2) + leap_day++; + + second = (time & 0x1f) << 1; + second += ((time >> 5) & 0x3f) * SECS_PER_MIN; + second += (time >> 11) * SECS_PER_HOUR; + second += (year * 365 + leap_day + + days_in_year[month] + day + + DAYS_DELTA) * SECS_PER_DAY; + + if (!sbi->options.tz_utc) + second += sys_tz.tz_minuteswest * SECS_PER_MIN; + + if (time_cs) { + ts->tv_sec = second + (time_cs / 100); + ts->tv_nsec = (time_cs % 100) * 10000000; + } else { + ts->tv_sec = second; + ts->tv_nsec = 0; + } } -/* Convert linear UNIX date to a MS-DOS time/date pair. */ -void fat_date_unix2dos(int unix_date, __le16 *time, __le16 *date, int tz_utc) +/* Convert linear UNIX date to a FAT time/date pair. */ +void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts, + __le16 *time, __le16 *date, u8 *time_cs) { - int day, year, nl_day, month; + time_t second = ts->tv_sec; + time_t day, leap_day, month, year; - if (!tz_utc) - unix_date -= sys_tz.tz_minuteswest*60; + if (!sbi->options.tz_utc) + second -= sys_tz.tz_minuteswest * SECS_PER_MIN; /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */ - if (unix_date < 315532800) - unix_date = 315532800; - - *time = cpu_to_le16((unix_date % 60)/2+(((unix_date/60) % 60) << 5)+ - (((unix_date/3600) % 24) << 11)); - day = unix_date/86400-3652; - year = day/365; - if ((year+3)/4+365*year > day) + if (second < UNIX_SECS_1980) { + *time = 0; + *date = cpu_to_le16((0 << 9) | (1 << 5) | 1); + if (time_cs) + *time_cs = 0; + return; + } +#if BITS_PER_LONG == 64 + if (second >= UNIX_SECS_2108) { + *time = cpu_to_le16((23 << 11) | (59 << 5) | 29); + *date = cpu_to_le16((127 << 9) | (12 << 5) | 31); + if (time_cs) + *time_cs = 199; + return; + } +#endif + + day = second / SECS_PER_DAY - DAYS_DELTA; + year = day / 365; + leap_day = (year + 3) / 4; + if (year > YEAR_2100) /* 2100 isn't leap year */ + leap_day--; + if (year * 365 + leap_day > day) year--; - day -= (year+3)/4+365*year; - if (day == 59 && !(year & 3)) { - nl_day = day; + leap_day = (year + 3) / 4; + if (year > YEAR_2100) /* 2100 isn't leap year */ + leap_day--; + day -= year * 365 + leap_day; + + if (IS_LEAP_YEAR(year) && day == days_in_year[3]) { month = 2; } else { - nl_day = (year & 3) || day <= 59 ? day : day-1; - for (month = 0; month < 12; month++) { - if (day_n[month] > nl_day) + if (IS_LEAP_YEAR(year) && day > days_in_year[3]) + day--; + for (month = 1; month < 12; month++) { + if (days_in_year[month + 1] > day) break; } } - *date = cpu_to_le16(nl_day-day_n[month-1]+1+(month << 5)+(year << 9)); -} + day -= days_in_year[month]; -EXPORT_SYMBOL_GPL(fat_date_unix2dos); + *time = cpu_to_le16(((second / SECS_PER_HOUR) % 24) << 11 + | ((second / SECS_PER_MIN) % 60) << 5 + | (second % SECS_PER_MIN) >> 1); + *date = cpu_to_le16((year << 9) | (month << 5) | (day + 1)); + if (time_cs) + *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000; +} +EXPORT_SYMBOL_GPL(fat_time_unix2fat); int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs) { |