/* $OpenBSD: a_time_posix.c,v 1.3 2023/01/01 16:58:23 miod Exp $ */ /* * Copyright (c) 2022, Google Inc. * Copyright (c) 2022, Bob Beck * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ /* * Time conversion to/from POSIX time_t and struct tm, with no support * for time zones other than UTC */ #include #include #include #include #define SECS_PER_HOUR (int64_t)(60 * 60) #define SECS_PER_DAY (int64_t)(24 * SECS_PER_HOUR) /* * Is a year/month/day combination valid, in the range from year 0000 * to 9999? */ static int is_valid_date(int year, int month, int day) { int days_in_month; if (day < 1 || month < 1 || year < 0 || year > 9999) return 0; switch (month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: days_in_month = 31; break; case 4: case 6: case 9: case 11: days_in_month = 30; break; case 2: if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) days_in_month = 29; else days_in_month = 28; break; default: return 0; } return day <= days_in_month; } /* * Is a time valid? Leap seconds of 60 are not considered valid, as * the POSIX time in seconds does not include them. */ static int is_valid_time(int hours, int minutes, int seconds) { return hours >= 0 && minutes >= 0 && seconds >= 0 && hours <= 23 && minutes <= 59 && seconds <= 59; } /* Is a int64 time representing a time within our expected range? */ static int is_valid_epoch_time(int64_t time) { /* 0000-01-01 00:00:00 UTC to 9999-12-31 23:59:59 UTC */ return (int64_t)-62167219200LL <= time && time <= (int64_t)253402300799LL; } /* * Inspired by algorithms presented in * https://howardhinnant.github.io/date_algorithms.html * (Public Domain) */ static int posix_time_from_utc(int year, int month, int day, int hours, int minutes, int seconds, int64_t *out_time) { int64_t era, year_of_era, day_of_year, day_of_era, posix_days; if (!is_valid_date(year, month, day) || !is_valid_time(hours, minutes, seconds)) return 0; if (month <= 2) year--; /* Start years on Mar 1, so leap days end a year. */ /* At this point year will be in the range -1 and 9999.*/ era = (year >= 0 ? year : year - 399) / 400; year_of_era = year - era * 400; day_of_year = (153 * (month > 2 ? month - 3 : month + 9) + 2) / 5 + day - 1; day_of_era = year_of_era * 365 + year_of_era / 4 - year_of_era / 100 + day_of_year; posix_days = era * 146097 + day_of_era - 719468; *out_time = posix_days * SECS_PER_DAY + hours * SECS_PER_HOUR + minutes * 60 + seconds; return 1; } /* * Inspired by algorithms presented in * https://howardhinnant.github.io/date_algorithms.html * (Public Domain) */ static int utc_from_posix_time(int64_t time, int *out_year, int *out_month, int *out_day, int *out_hours, int *out_minutes, int *out_seconds) { int64_t days, leftover_seconds, era, day_of_era, year_of_era, day_of_year, month_of_year; if (!is_valid_epoch_time(time)) return 0; days = time / SECS_PER_DAY; leftover_seconds = time % SECS_PER_DAY; if (leftover_seconds < 0) { days--; leftover_seconds += SECS_PER_DAY; } days += 719468; /* Shift to starting epoch of Mar 1 0000. */ /* At this point, days will be in the range -61 and 3652364. */ era = (days > 0 ? days : days - 146096) / 146097; day_of_era = days - era * 146097; year_of_era = (day_of_era - day_of_era / 1460 + day_of_era / 36524 - day_of_era / 146096) / 365; *out_year = year_of_era + era * 400; /* Year starts on Mar 1 */ day_of_year = day_of_era - (365 * year_of_era + year_of_era / 4 - year_of_era / 100); month_of_year = (5 * day_of_year + 2) / 153; *out_month = (month_of_year < 10 ? month_of_year + 3 : month_of_year - 9); if (*out_month <= 2) (*out_year)++; /* Adjust year back to Jan 1 start of year. */ *out_day = day_of_year - (153 * month_of_year + 2) / 5 + 1; *out_hours = leftover_seconds / SECS_PER_HOUR; leftover_seconds %= SECS_PER_HOUR; *out_minutes = leftover_seconds / 60; *out_seconds = leftover_seconds % 60; return 1; } static int asn1_time_tm_to_posix(const struct tm *tm, int64_t *out) { /* Ensure additions below do not overflow */ if (tm->tm_year > 9999) return 0; if (tm->tm_mon > 12) return 0; return posix_time_from_utc(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec, out); } static int asn1_time_posix_to_tm(int64_t time, struct tm *out_tm) { memset(out_tm, 0, sizeof(struct tm)); if (!utc_from_posix_time(time, &out_tm->tm_year, &out_tm->tm_mon, &out_tm->tm_mday, &out_tm->tm_hour, &out_tm->tm_min, &out_tm->tm_sec)) return 0; out_tm->tm_year -= 1900; out_tm->tm_mon -= 1; return 1; } int asn1_time_tm_to_time_t(const struct tm *tm, time_t *out) { int64_t posix_time; if (!asn1_time_tm_to_posix(tm, &posix_time)) return 0; #ifdef SMALL_TIME_T /* For portable. */ if (sizeof(time_t) == sizeof(int32_t) && (posix_time > INT32_MAX || posix_time < INT32_MIN)) return 0; #endif *out = posix_time; return 1; } int asn1_time_time_t_to_tm(const time_t *time, struct tm *out_tm) { int64_t posix_time = *time; return asn1_time_posix_to_tm(posix_time, out_tm); } int OPENSSL_gmtime_adj(struct tm *tm, int off_day, long offset_sec) { int64_t posix_time; /* Ensure additions below do not overflow */ if (tm->tm_year > 9999) return 0; if (tm->tm_mon > 12) return 0; if (!posix_time_from_utc(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec, &posix_time)) return 0; if (!utc_from_posix_time(posix_time + off_day * SECS_PER_DAY + offset_sec, &tm->tm_year, &tm->tm_mon, &tm->tm_mday, &tm->tm_hour, &tm->tm_min, &tm->tm_sec)) return 0; tm->tm_year -= 1900; tm->tm_mon -= 1; return 1; } int OPENSSL_gmtime_diff(int *out_days, int *out_secs, const struct tm *from, const struct tm *to) { int64_t time_to, time_from, timediff, daydiff; if (!posix_time_from_utc(to->tm_year + 1900, to->tm_mon + 1, to->tm_mday, to->tm_hour, to->tm_min, to->tm_sec, &time_to)) return 0; if (!posix_time_from_utc(from->tm_year + 1900, from->tm_mon + 1, from->tm_mday, from->tm_hour, from->tm_min, from->tm_sec, &time_from)) return 0; timediff = time_to - time_from; daydiff = timediff / SECS_PER_DAY; timediff %= SECS_PER_DAY; if (daydiff > INT_MAX || daydiff < INT_MIN) return 0; *out_secs = timediff; *out_days = daydiff; return 1; }