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Subject[PATCH 2/2] exfat: stop using 32-bit time_t
Date
time_t suffers from overflow problems and should not be used.

In exfat, it is currently used in two open-coded time64_to_tm()
implementations. Changes those to use the existing function instead.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/staging/exfat/exfat_super.c | 164 +++++++---------------------
1 file changed, 38 insertions(+), 126 deletions(-)

diff --git a/drivers/staging/exfat/exfat_super.c b/drivers/staging/exfat/exfat_super.c
index 37e78620723f..7fd56654498f 100644
--- a/drivers/staging/exfat/exfat_super.c
+++ b/drivers/staging/exfat/exfat_super.c
@@ -55,129 +55,65 @@ static int exfat_write_inode(struct inode *inode,
static void exfat_write_super(struct super_block *sb);

#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_DECADE (365 * 10 + 2)
-/* 120 (2100 - 1980) isn't leap year */
-#define NO_LEAP_YEAR_2100 (120)
-#define IS_LEAP_YEAR(y) (!((y) & 0x3) && (y) != NO_LEAP_YEAR_2100)
-
-#define SECS_PER_MIN (60)
-#define SECS_PER_HOUR (60 * SECS_PER_MIN)
-#define SECS_PER_DAY (24 * SECS_PER_HOUR)
-
-#define MAKE_LEAP_YEAR(leap_year, year) \
- do { \
- if (unlikely(year > NO_LEAP_YEAR_2100)) \
- leap_year = ((year + 3) / 4) - 1; \
- else \
- leap_year = ((year + 3) / 4); \
- } while (0)
-
-/* Linear day numbers of the respective 1sts in non-leap years. */
-static time_t accum_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 FAT time/date pair to a UNIX date (seconds since 1 1 70). */
static void exfat_time_fat2unix(struct exfat_sb_info *sbi,
struct timespec64 *ts, struct date_time_t *tp)
{
- time_t year = tp->Year;
- time_t ld;
-
- MAKE_LEAP_YEAR(ld, year);
-
- if (IS_LEAP_YEAR(year) && (tp->Month) > 2)
- ld++;
-
- ts->tv_sec = tp->Second +
- tp->Minute * SECS_PER_MIN +
- tp->Hour * SECS_PER_HOUR +
- (ld + accum_days_in_year[(tp->Month)] +
- (tp->Day - 1)) * SECS_PER_DAY +
- (year * 365 + DAYS_DELTA_DECADE) * SECS_PER_DAY +
- sys_tz.tz_minuteswest * SECS_PER_MIN;
+ ts->tv_sec = mktime64(tp->Year + 1980, tp->Month + 1, tp->Day,
+ tp->Hour, tp->Minute, tp->Second);

- ts->tv_nsec = 0;
+ ts->tv_nsec = tp->MilliSecond * NSEC_PER_MSEC;
}

/* Convert linear UNIX date to a FAT time/date pair. */
static void exfat_time_unix2fat(struct exfat_sb_info *sbi,
struct timespec64 *ts, struct date_time_t *tp)
{
- time_t second = ts->tv_sec;
- time_t day, month, year;
- time_t ld;
+ time64_t second = ts->tv_sec;
+ struct tm tm;

- second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
+ time64_to_tm(second, 0, &tm);

- /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
if (second < UNIX_SECS_1980) {
- tp->Second = 0;
- tp->Minute = 0;
- tp->Hour = 0;
- tp->Day = 1;
- tp->Month = 1;
- tp->Year = 0;
+ tp->MilliSecond = 0;
+ tp->Second = 0;
+ tp->Minute = 0;
+ tp->Hour = 0;
+ tp->Day = 1;
+ tp->Month = 1;
+ tp->Year = 0;
return;
}
-#if (BITS_PER_LONG == 64)
+
if (second >= UNIX_SECS_2108) {
- tp->Second = 59;
- tp->Minute = 59;
- tp->Hour = 23;
- tp->Day = 31;
- tp->Month = 12;
- tp->Year = 127;
+ tp->MilliSecond = 999;
+ tp->Second = 59;
+ tp->Minute = 59;
+ tp->Hour = 23;
+ tp->Day = 31;
+ tp->Month = 12;
+ tp->Year = 127;
return;
}
-#endif
- day = second / SECS_PER_DAY - DAYS_DELTA_DECADE;
- year = day / 365;
- MAKE_LEAP_YEAR(ld, year);
- if (year * 365 + ld > day)
- year--;
-
- MAKE_LEAP_YEAR(ld, year);
- day -= year * 365 + ld;

- if (IS_LEAP_YEAR(year) && day == accum_days_in_year[3]) {
- month = 2;
- } else {
- if (IS_LEAP_YEAR(year) && day > accum_days_in_year[3])
- day--;
- for (month = 1; month < 12; month++) {
- if (accum_days_in_year[month + 1] > day)
- break;
- }
- }
- day -= accum_days_in_year[month];
-
- tp->Second = second % SECS_PER_MIN;
- tp->Minute = (second / SECS_PER_MIN) % 60;
- tp->Hour = (second / SECS_PER_HOUR) % 24;
- tp->Day = day + 1;
- tp->Month = month;
- tp->Year = year;
+ tp->MilliSecond = ts->tv_nsec / NSEC_PER_MSEC;
+ tp->Second = tm.tm_sec;
+ tp->Minute = tm.tm_min;
+ tp->Hour = tm.tm_hour;
+ tp->Day = tm.tm_mday;
+ tp->Month = tm.tm_mon + 1;
+ tp->Year = tm.tm_year + 1900 - 1980;
}

struct timestamp_t *tm_current(struct timestamp_t *tp)
{
- struct timespec64 ts;
- time_t second, day, leap_day, month, year;
-
- ktime_get_real_ts64(&ts);
+ time64_t second = ktime_get_real_seconds();
+ struct tm tm;

- second = ts.tv_sec;
- second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
+ time64_to_tm(second, 0, &tm);

- /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
if (second < UNIX_SECS_1980) {
tp->sec = 0;
tp->min = 0;
@@ -187,7 +123,7 @@ struct timestamp_t *tm_current(struct timestamp_t *tp)
tp->year = 0;
return tp;
}
-#if BITS_PER_LONG == 64
+
if (second >= UNIX_SECS_2108) {
tp->sec = 59;
tp->min = 59;
@@ -197,37 +133,13 @@ struct timestamp_t *tm_current(struct timestamp_t *tp)
tp->year = 127;
return tp;
}
-#endif
-
- day = second / SECS_PER_DAY - DAYS_DELTA_DECADE;
- year = day / 365;
-
- MAKE_LEAP_YEAR(leap_day, year);
- if (year * 365 + leap_day > day)
- year--;

- MAKE_LEAP_YEAR(leap_day, year);
-
- day -= year * 365 + leap_day;
-
- if (IS_LEAP_YEAR(year) && day == accum_days_in_year[3]) {
- month = 2;
- } else {
- if (IS_LEAP_YEAR(year) && day > accum_days_in_year[3])
- day--;
- for (month = 1; month < 12; month++) {
- if (accum_days_in_year[month + 1] > day)
- break;
- }
- }
- day -= accum_days_in_year[month];
-
- tp->sec = second % SECS_PER_MIN;
- tp->min = (second / SECS_PER_MIN) % 60;
- tp->hour = (second / SECS_PER_HOUR) % 24;
- tp->day = day + 1;
- tp->mon = month;
- tp->year = year;
+ tp->sec = tm.tm_sec;
+ tp->min = tm.tm_min;
+ tp->hour = tm.tm_hour;
+ tp->day = tm.tm_mday;
+ tp->mon = tm.tm_mon + 1;
+ tp->year = tm.tm_year + 1900 - 1980;

return tp;
}
--
2.20.0
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