staging: exfat: stop using 32-bit time_t

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>
Link: https://lore.kernel.org/r/20190906150917.1025250-2-arnd@arndb.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/exfat/exfat_super.c b/drivers/staging/exfat/exfat_super.c
index 68d89cee359e83e46c86d3598cc9e8a02c4cc881..60dfea73a7a43d563a95eb069e136402d8c6a2d3 100644 (file)
--- a/drivers/staging/exfat/exfat_super.c
+++ b/drivers/staging/exfat/exfat_super.c
@@ -53,129 +53,65 @@ 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;
@@ -185,7 +121,7 @@ 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;
@@ -195,37 +131,13 @@ 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;
 }