+ }
+
+/* Take a tm structure and add an offset to it. This avoids any OS issues
+ * with restricted date types and overflows which cause the year 2038
+ * problem.
+ */
+
+#define SECS_PER_DAY (24 * 60 * 60)
+
+static long date_to_julian(int y, int m, int d);
+static void julian_to_date(long jd, int *y, int *m, int *d);
+static int julian_adj(struct tm *tm, int off_day, long offset_sec,
+ long *pday, int *psec);
+
+int OPENSSL_gmtime_adj(struct tm *tm, int off_day, long offset_sec)
+ {
+ int time_sec, time_year, time_month, time_day;
+ long time_jd;
+
+ /* Convert time and offset into julian day and seconds */
+ if (!julian_adj(tm, off_day, offset_sec, &time_jd, &time_sec))
+ return 0;
+
+ /* Convert Julian day back to date */
+
+ julian_to_date(time_jd, &time_year, &time_month, &time_day);
+
+ if (time_year < 1900 || time_year > 9999)
+ return 0;
+
+ /* Update tm structure */
+
+ tm->tm_year = time_year - 1900;
+ tm->tm_mon = time_month - 1;
+ tm->tm_mday = time_day;
+
+ tm->tm_hour = time_sec / 3600;
+ tm->tm_min = (time_sec / 60) % 60;
+ tm->tm_sec = time_sec % 60;
+
+ return 1;
+
+}
+
+int OPENSSL_gmtime_diff(struct tm *from, struct tm *to, int *pday, int *psec)
+ {
+ int from_sec, to_sec, diff_sec;
+ long from_jd, to_jd, diff_day;
+ if (!julian_adj(from, 0, 0, &from_jd, &from_sec))
+ return 0;
+ if (!julian_adj(to, 0, 0, &to_jd, &to_sec))
+ return 0;
+ diff_day = to_jd - from_jd;
+ diff_sec = to_sec - from_sec;
+ /* Adjust differences so both positive or both negative */
+ if (diff_day > 0 && diff_sec < 0)
+ {
+ diff_day--;
+ diff_sec += SECS_PER_DAY;
+ }
+ if (diff_day < 0 && diff_sec > 0)
+ {
+ diff_day++;
+ diff_sec -= SECS_PER_DAY;
+ }
+
+ *pday = (int)diff_day;
+ *psec = diff_sec;
+
+ return 1;
+
+ }
+
+
+/* Convert tm structure and offset into julian day and seconds */
+static int julian_adj(struct tm *tm, int off_day, long offset_sec,
+ long *pday, int *psec)
+ {
+ int offset_hms, offset_day;
+ long time_jd;
+ int time_year, time_month, time_day;
+ /* split offset into days and day seconds */
+ offset_day = offset_sec / SECS_PER_DAY;
+ /* Avoid sign issues with % operator */
+ offset_hms = offset_sec - (offset_day * SECS_PER_DAY);
+ offset_day += off_day;
+ /* Add current time seconds to offset */
+ offset_hms += tm->tm_hour * 3600 + tm->tm_min * 60 + tm->tm_sec;
+ /* Adjust day seconds if overflow */
+ if (offset_hms >= SECS_PER_DAY)
+ {
+ offset_day++;
+ offset_hms -= SECS_PER_DAY;
+ }
+ else if (offset_hms < 0)
+ {
+ offset_day--;
+ offset_hms += SECS_PER_DAY;
+ }
+
+ /* Convert date of time structure into a Julian day number.
+ */
+
+ time_year = tm->tm_year + 1900;
+ time_month = tm->tm_mon + 1;
+ time_day = tm->tm_mday;
+
+ time_jd = date_to_julian(time_year, time_month, time_day);
+
+ /* Work out Julian day of new date */
+ time_jd += offset_day;
+
+ if (time_jd < 0)
+ return 0;
+
+ *pday = time_jd;
+ *psec = offset_hms;
+ return 1;
+ }
+
+
+/* Convert date to and from julian day
+ * Uses Fliegel & Van Flandern algorithm
+ */
+static long date_to_julian(int y, int m, int d)
+{
+ return (1461 * (y + 4800 + (m - 14) / 12)) / 4 +
+ (367 * (m - 2 - 12 * ((m - 14) / 12))) / 12 -
+ (3 * ((y + 4900 + (m - 14) / 12) / 100)) / 4 +
+ d - 32075;
+}
+
+static void julian_to_date(long jd, int *y, int *m, int *d)
+ {
+ long L = jd + 68569;
+ long n = (4 * L) / 146097;
+ long i, j;
+
+ L = L - (146097 * n + 3) / 4;
+ i = (4000 * (L + 1)) / 1461001;
+ L = L - (1461 * i) / 4 + 31;
+ j = (80 * L) / 2447;
+ *d = L - (2447 * j) / 80;
+ L = j / 11;
+ *m = j + 2 - (12 * L);
+ *y = 100 * (n - 49) + i + L;
+ }
+
+#ifdef OPENSSL_TIME_TEST
+
+#include <stdio.h>
+
+/* Time checking test code. Check times are identical for a wide range of
+ * offsets. This should be run on a machine with 64 bit time_t or it will
+ * trigger the very errors the routines fix.
+ */
+
+int main(int argc, char **argv)
+ {
+ long offset;
+ for (offset = 0; offset < 1000000; offset++)
+ {
+ check_time(offset);
+ check_time(-offset);
+ check_time(offset * 1000);
+ check_time(-offset * 1000);
+ }
+ }
+
+int check_time(long offset)
+ {
+ struct tm tm1, tm2, o1;
+ int off_day, off_sec;
+ long toffset;
+ time_t t1, t2;
+ time(&t1);
+ t2 = t1 + offset;
+ OPENSSL_gmtime(&t2, &tm2);
+ OPENSSL_gmtime(&t1, &tm1);
+ o1 = tm1;
+ OPENSSL_gmtime_adj(&tm1, 0, offset);
+ if ((tm1.tm_year != tm2.tm_year) ||
+ (tm1.tm_mon != tm2.tm_mon) ||
+ (tm1.tm_mday != tm2.tm_mday) ||
+ (tm1.tm_hour != tm2.tm_hour) ||
+ (tm1.tm_min != tm2.tm_min) ||
+ (tm1.tm_sec != tm2.tm_sec))
+ {
+ fprintf(stderr, "TIME ERROR!!\n");
+ fprintf(stderr, "Time1: %d/%d/%d, %d:%02d:%02d\n",
+ tm2.tm_mday, tm2.tm_mon + 1, tm2.tm_year + 1900,
+ tm2.tm_hour, tm2.tm_min, tm2.tm_sec);
+ fprintf(stderr, "Time2: %d/%d/%d, %d:%02d:%02d\n",
+ tm1.tm_mday, tm1.tm_mon + 1, tm1.tm_year + 1900,
+ tm1.tm_hour, tm1.tm_min, tm1.tm_sec);
+ return 0;
+ }
+ OPENSSL_gmtime_diff(&o1, &tm1, &off_day, &off_sec);
+ toffset = (long)off_day * SECS_PER_DAY + off_sec;
+ if (offset != toffset)
+ {
+ fprintf(stderr, "TIME OFFSET ERROR!!\n");
+ fprintf(stderr, "Expected %ld, Got %ld (%d:%d)\n",
+ offset, toffset, off_day, off_sec);
+ return 0;
+ }
+ return 1;
+ }
+
+#endif