/src/git/date.c

Source
/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */

#define DISABLE_SIGN_COMPARE_WARNINGS

#include "git-compat-util.h"
#include "date.h"
#include "gettext.h"
#include "pager.h"
#include "strbuf.h"

/*
 * This is like mktime, but without normalization of tm_wday and tm_yday.
 */
time_t tm_to_time_t(const struct tm *tm)
{
  static const int mdays[] = {
      0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
  };
  int year = tm->tm_year - 70;
  int month = tm->tm_mon;
  int day = tm->tm_mday;

  if (year < 0 || year > 129) /* algo only works for 1970-2099 */
    return -1;
  if (month < 0 || month > 11) /* array bounds */
    return -1;
  if (month < 2 || (year + 2) % 4)
    day--;
  if (tm->tm_hour < 0 || tm->tm_min < 0 || tm->tm_sec < 0)
    return -1;
  return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
    tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
}

static const char *month_names[] = {
  "January", "February", "March", "April", "May", "June",
  "July", "August", "September", "October", "November", "December"
};

static const char *weekday_names[] = {
  "Sundays", "Mondays", "Tuesdays", "Wednesdays", "Thursdays", "Fridays", "Saturdays"
};

static time_t gm_time_t(timestamp_t time, int tz)
{
  int minutes;

  minutes = tz < 0 ? -tz : tz;
  minutes = (minutes / 100)*60 + (minutes % 100);
  minutes = tz < 0 ? -minutes : minutes;

  if (minutes > 0) {
    if (unsigned_add_overflows(time, minutes * 60))
      die("Timestamp+tz too large: %"PRItime" +%04d",
          time, tz);
  } else if (time < -minutes * 60)
    die("Timestamp before Unix epoch: %"PRItime" %04d", time, tz);
  time += minutes * 60;
  if (date_overflows(time))
    die("Timestamp too large for this system: %"PRItime, time);
  return (time_t)time;
}

/*
 * The "tz" thing is passed in as this strange "decimal parse of tz"
 * thing, which means that tz -0100 is passed in as the integer -100,
 * even though it means "sixty minutes off"
 */
static struct tm *time_to_tm(timestamp_t time, int tz, struct tm *tm)
{
  time_t t = gm_time_t(time, tz);
  return gmtime_r(&t, tm);
}

static struct tm *time_to_tm_local(timestamp_t time, struct tm *tm)
{
  time_t t = time;
  return localtime_r(&t, tm);
}

/*
 * Fill in the localtime 'struct tm' for the supplied time,
 * and return the local tz.
 */
static int local_time_tzoffset(time_t t, struct tm *tm)
{
  time_t t_local;
  int offset, eastwest;

  localtime_r(&t, tm);
  t_local = tm_to_time_t(tm);
  if (t_local == -1)
    return 0; /* error; just use +0000 */
  if (t_local < t) {
    eastwest = -1;
    offset = t - t_local;
  } else {
    eastwest = 1;
    offset = t_local - t;
  }
  offset /= 60; /* in minutes */
  offset = (offset % 60) + ((offset / 60) * 100);
  return offset * eastwest;
}

/*
 * What value of "tz" was in effect back then at "time" in the
 * local timezone?
 */
static int local_tzoffset(timestamp_t time)
{
  struct tm tm;

  if (date_overflows(time))
    die("Timestamp too large for this system: %"PRItime, time);

  return local_time_tzoffset((time_t)time, &tm);
}

static void get_time(struct timeval *now)
{
  const char *x;

  x = getenv("GIT_TEST_DATE_NOW");
  if (x) {
    now->tv_sec = atoi(x);
    now->tv_usec = 0;
  }
  else
    gettimeofday(now, NULL);
}

void show_date_relative(timestamp_t time, struct strbuf *timebuf)
{
  struct timeval now;
  timestamp_t diff;

  get_time(&now);
  if (now.tv_sec < time) {
    strbuf_addstr(timebuf, _("in the future"));
    return;
  }
  diff = now.tv_sec - time;
  if (diff < 90) {
    strbuf_addf(timebuf,
       Q_("%"PRItime" second ago", "%"PRItime" seconds ago", diff), diff);
    return;
  }
  /* Turn it into minutes */
  diff = (diff + 30) / 60;
  if (diff < 90) {
    strbuf_addf(timebuf,
       Q_("%"PRItime" minute ago", "%"PRItime" minutes ago", diff), diff);
    return;
  }
  /* Turn it into hours */
  diff = (diff + 30) / 60;
  if (diff < 36) {
    strbuf_addf(timebuf,
       Q_("%"PRItime" hour ago", "%"PRItime" hours ago", diff), diff);
    return;
  }
  /* We deal with number of days from here on */
  diff = (diff + 12) / 24;
  if (diff < 14) {
    strbuf_addf(timebuf,
       Q_("%"PRItime" day ago", "%"PRItime" days ago", diff), diff);
    return;
  }
  /* Say weeks for the past 10 weeks or so */
  if (diff < 70) {
    strbuf_addf(timebuf,
       Q_("%"PRItime" week ago", "%"PRItime" weeks ago", (diff + 3) / 7),
       (diff + 3) / 7);
    return;
  }
  /* Say months for the past 12 months or so */
  if (diff < 365) {
    strbuf_addf(timebuf,
       Q_("%"PRItime" month ago", "%"PRItime" months ago", (diff + 15) / 30),
       (diff + 15) / 30);
    return;
  }
  /* Give years and months for 5 years or so */
  if (diff < 1825) {
    timestamp_t totalmonths = (diff * 12 * 2 + 365) / (365 * 2);
    timestamp_t years = totalmonths / 12;
    timestamp_t months = totalmonths % 12;
    if (months) {
      struct strbuf sb = STRBUF_INIT;
      strbuf_addf(&sb, Q_("%"PRItime" year", "%"PRItime" years", years), years);
      strbuf_addf(timebuf,
         /* TRANSLATORS: "%s" is "<n> years" */
         Q_("%s, %"PRItime" month ago", "%s, %"PRItime" months ago", months),
         sb.buf, months);
      strbuf_release(&sb);
    } else
      strbuf_addf(timebuf,
         Q_("%"PRItime" year ago", "%"PRItime" years ago", years), years);
    return;
  }
  /* Otherwise, just years. Centuries is probably overkill. */
  strbuf_addf(timebuf,
     Q_("%"PRItime" year ago", "%"PRItime" years ago", (diff + 183) / 365),
     (diff + 183) / 365);
}

struct date_mode date_mode_from_type(enum date_mode_type type)
{
  struct date_mode mode = DATE_MODE_INIT;
  if (type == DATE_STRFTIME)
    BUG("cannot create anonymous strftime date_mode struct");
  mode.type = type;
  return mode;
}

static void show_date_normal(struct strbuf *buf, timestamp_t time, struct tm *tm, int tz, struct tm *human_tm, int human_tz, int local)
{
  struct {
    unsigned int  year:1,
        date:1,
        wday:1,
        time:1,
        seconds:1,
        tz:1;
  } hide = { 0 };

  hide.tz = local || tz == human_tz;
  hide.year = tm->tm_year == human_tm->tm_year;
  if (hide.year) {
    if (tm->tm_mon == human_tm->tm_mon) {
      if (tm->tm_mday > human_tm->tm_mday) {
        /* Future date: think timezones */
      } else if (tm->tm_mday == human_tm->tm_mday) {
        hide.date = hide.wday = 1;
      } else if (tm->tm_mday + 5 > human_tm->tm_mday) {
        /* Leave just weekday if it was a few days ago */
        hide.date = 1;
      }
    }
  }

  /* Show "today" times as just relative times */
  if (hide.wday) {
    show_date_relative(time, buf);
    return;
  }

  /*
   * Always hide seconds for human-readable.
   * Hide timezone if showing date.
   * Hide weekday and time if showing year.
   *
   * The logic here is two-fold:
   *  (a) only show details when recent enough to matter
   *  (b) keep the maximum length "similar", and in check
   */
  if (human_tm->tm_year) {
    hide.seconds = 1;
    hide.tz |= !hide.date;
    hide.wday = hide.time = !hide.year;
  }

  if (!hide.wday)
    strbuf_addf(buf, "%.3s ", weekday_names[tm->tm_wday]);
  if (!hide.date)
    strbuf_addf(buf, "%.3s %d ", month_names[tm->tm_mon], tm->tm_mday);

  /* Do we want AM/PM depending on locale? */
  if (!hide.time) {
    strbuf_addf(buf, "%02d:%02d", tm->tm_hour, tm->tm_min);
    if (!hide.seconds)
      strbuf_addf(buf, ":%02d", tm->tm_sec);
  } else
    strbuf_rtrim(buf);

  if (!hide.year)
    strbuf_addf(buf, " %d", tm->tm_year + 1900);

  if (!hide.tz)
    strbuf_addf(buf, " %+05d", tz);
}

const char *show_date(timestamp_t time, int tz, struct date_mode mode)
{
  struct tm *tm;
  struct tm tmbuf = { 0 };
  struct tm human_tm = { 0 };
  int human_tz = -1;
  static struct strbuf timebuf = STRBUF_INIT;

  if (mode.type == DATE_UNIX) {
    strbuf_reset(&timebuf);
    strbuf_addf(&timebuf, "%"PRItime, time);
    return timebuf.buf;
  }

  if (mode.type == DATE_HUMAN) {
    struct timeval now;

    get_time(&now);

    /* Fill in the data for "current time" in human_tz and human_tm */
    human_tz = local_time_tzoffset(now.tv_sec, &human_tm);
  }

  if (mode.local)
    tz = local_tzoffset(time);

  if (mode.type == DATE_RAW) {
    strbuf_reset(&timebuf);
    strbuf_addf(&timebuf, "%"PRItime" %+05d", time, tz);
    return timebuf.buf;
  }

  if (mode.type == DATE_RELATIVE) {
    strbuf_reset(&timebuf);
    show_date_relative(time, &timebuf);
    return timebuf.buf;
  }

  if (mode.local)
    tm = time_to_tm_local(time, &tmbuf);
  else
    tm = time_to_tm(time, tz, &tmbuf);
  if (!tm) {
    tm = time_to_tm(0, 0, &tmbuf);
    tz = 0;
  }

  strbuf_reset(&timebuf);
  if (mode.type == DATE_SHORT)
    strbuf_addf(&timebuf, "%04d-%02d-%02d", tm->tm_year + 1900,
        tm->tm_mon + 1, tm->tm_mday);
  else if (mode.type == DATE_ISO8601)
    strbuf_addf(&timebuf, "%04d-%02d-%02d %02d:%02d:%02d %+05d",
        tm->tm_year + 1900,
        tm->tm_mon + 1,
        tm->tm_mday,
        tm->tm_hour, tm->tm_min, tm->tm_sec,
        tz);
  else if (mode.type == DATE_ISO8601_STRICT) {
    strbuf_addf(&timebuf, "%04d-%02d-%02dT%02d:%02d:%02d",
        tm->tm_year + 1900,
        tm->tm_mon + 1,
        tm->tm_mday,
        tm->tm_hour, tm->tm_min, tm->tm_sec);
    if (tz == 0) {
      strbuf_addch(&timebuf, 'Z');
    } else {
      strbuf_addch(&timebuf, tz >= 0 ? '+' : '-');
      tz = abs(tz);
      strbuf_addf(&timebuf, "%02d:%02d", tz / 100, tz % 100);
    }
  } else if (mode.type == DATE_RFC2822)
    strbuf_addf(&timebuf, "%.3s, %d %.3s %d %02d:%02d:%02d %+05d",
      weekday_names[tm->tm_wday], tm->tm_mday,
      month_names[tm->tm_mon], tm->tm_year + 1900,
      tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
  else if (mode.type == DATE_STRFTIME)
    strbuf_addftime(&timebuf, mode.strftime_fmt, tm, tz,
        !mode.local);
  else
    show_date_normal(&timebuf, time, tm, tz, &human_tm, human_tz, mode.local);
  return timebuf.buf;
}

/*
 * Check these. And note how it doesn't do the summer-time conversion.
 *
 * In my world, it's always summer, and things are probably a bit off
 * in other ways too.
 */
static const struct {
  const char *name;
  int offset;
  int dst;
} timezone_names[] = {
  { "IDLW", -12, 0, },  /* International Date Line West */
  { "NT",   -11, 0, },  /* Nome */
  { "CAT",  -10, 0, },  /* Central Alaska */
  { "HST",  -10, 0, },  /* Hawaii Standard */
  { "HDT",  -10, 1, },  /* Hawaii Daylight */
  { "YST",   -9, 0, },  /* Yukon Standard */
  { "YDT",   -9, 1, },  /* Yukon Daylight */
  { "PST",   -8, 0, },  /* Pacific Standard */
  { "PDT",   -8, 1, },  /* Pacific Daylight */
  { "MST",   -7, 0, },  /* Mountain Standard */
  { "MDT",   -7, 1, },  /* Mountain Daylight */
  { "CST",   -6, 0, },  /* Central Standard */
  { "CDT",   -6, 1, },  /* Central Daylight */
  { "EST",   -5, 0, },  /* Eastern Standard */
  { "EDT",   -5, 1, },  /* Eastern Daylight */
  { "AST",   -3, 0, },  /* Atlantic Standard */
  { "ADT",   -3, 1, },  /* Atlantic Daylight */
  { "WAT",   -1, 0, },  /* West Africa */

  { "GMT",    0, 0, },  /* Greenwich Mean */
  { "UTC",    0, 0, },  /* Universal (Coordinated) */
  { "Z",      0, 0, },    /* Zulu, alias for UTC */

  { "WET",    0, 0, },  /* Western European */
  { "BST",    0, 1, },  /* British Summer */
  { "CET",   +1, 0, },  /* Central European */
  { "MET",   +1, 0, },  /* Middle European */
  { "MEWT",  +1, 0, },  /* Middle European Winter */
  { "MEST",  +1, 1, },  /* Middle European Summer */
  { "CEST",  +1, 1, },  /* Central European Summer */
  { "MESZ",  +1, 1, },  /* Middle European Summer */
  { "FWT",   +1, 0, },  /* French Winter */
  { "FST",   +1, 1, },  /* French Summer */
  { "EET",   +2, 0, },  /* Eastern Europe, USSR Zone 1 */
  { "EEST",  +2, 1, },  /* Eastern European Daylight */
  { "WAST",  +7, 0, },  /* West Australian Standard */
  { "WADT",  +7, 1, },  /* West Australian Daylight */
  { "CCT",   +8, 0, },  /* China Coast, USSR Zone 7 */
  { "JST",   +9, 0, },  /* Japan Standard, USSR Zone 8 */
  { "EAST", +10, 0, },  /* Eastern Australian Standard */
  { "EADT", +10, 1, },  /* Eastern Australian Daylight */
  { "GST",  +10, 0, },  /* Guam Standard, USSR Zone 9 */
  { "NZT",  +12, 0, },  /* New Zealand */
  { "NZST", +12, 0, },  /* New Zealand Standard */
  { "NZDT", +12, 1, },  /* New Zealand Daylight */
  { "IDLE", +12, 0, },  /* International Date Line East */
};

static int match_string(const char *date, const char *str)
{
  int i = 0;

  for (i = 0; *date; date++, str++, i++) {
    if (*date == *str)
      continue;
    if (toupper(*date) == toupper(*str))
      continue;
    if (!isalnum(*date))
      break;
    return 0;
  }
  return i;
}

static int skip_alpha(const char *date)
{
  int i = 0;
  do {
    i++;
  } while (isalpha(date[i]));
  return i;
}

/*
* Parse month, weekday, or timezone name
*/
static int match_alpha(const char *date, struct tm *tm, int *offset)
{
  int i;

  for (i = 0; i < 12; i++) {
    int match = match_string(date, month_names[i]);
    if (match >= 3) {
      tm->tm_mon = i;
      return match;
    }
  }

  for (i = 0; i < 7; i++) {
    int match = match_string(date, weekday_names[i]);
    if (match >= 3) {
      tm->tm_wday = i;
      return match;
    }
  }

  for (i = 0; i < ARRAY_SIZE(timezone_names); i++) {
    int match = match_string(date, timezone_names[i].name);
    if (match >= 3 || match == strlen(timezone_names[i].name)) {
      int off = timezone_names[i].offset;

      /* This is bogus, but we like summer */
      off += timezone_names[i].dst;

      /* Only use the tz name offset if we don't have anything better */
      if (*offset == -1)
        *offset = 60*off;

      return match;
    }
  }

  if (match_string(date, "PM") == 2) {
    tm->tm_hour = (tm->tm_hour % 12) + 12;
    return 2;
  }

  if (match_string(date, "AM") == 2) {
    tm->tm_hour = (tm->tm_hour % 12) + 0;
    return 2;
  }

  /* ISO-8601 allows yyyymmDD'T'HHMMSS, with less precision */
  if (*date == 'T' && isdigit(date[1]) && tm->tm_hour == -1) {
    tm->tm_min = tm->tm_sec = 0;
    return 1;
  }

  /* BAD CRAP */
  return skip_alpha(date);
}

static int set_date(int year, int month, int day, struct tm *now_tm, time_t now, struct tm *tm)
{
  if (month > 0 && month < 13 && day > 0 && day < 32) {
    struct tm check = *tm;
    struct tm *r = (now_tm ? &check : tm);
    time_t specified;

    r->tm_mon = month - 1;
    r->tm_mday = day;
    if (year == -1) {
      if (!now_tm)
        return 1;
      r->tm_year = now_tm->tm_year;
    }
    else if (year >= 1970 && year < 2100)
      r->tm_year = year - 1900;
    else if (year > 70 && year < 100)
      r->tm_year = year;
    else if (year < 38)
      r->tm_year = year + 100;
    else
      return -1;
    if (!now_tm)
      return 0;

    specified = tm_to_time_t(r);

    /* Be it commit time or author time, it does not make
     * sense to specify timestamp way into the future.  Make
     * sure it is not later than ten days from now...
     */
    if ((specified != -1) && (now + 10*24*3600 < specified))
      return -1;
    tm->tm_mon = r->tm_mon;
    tm->tm_mday = r->tm_mday;
    if (year != -1)
      tm->tm_year = r->tm_year;
    return 0;
  }
  return -1;
}

static int set_time(long hour, long minute, long second, struct tm *tm)
{
  /* We accept 61st second because of leap second */
  if (0 <= hour && hour <= 24 &&
      0 <= minute && minute < 60 &&
      0 <= second && second <= 60) {
    tm->tm_hour = hour;
    tm->tm_min = minute;
    tm->tm_sec = second;
    return 0;
  }
  return -1;
}

static int is_date_known(struct tm *tm)
{
  return tm->tm_year != -1 && tm->tm_mon != -1 && tm->tm_mday != -1;
}

static int match_multi_number(timestamp_t num, char c, const char *date,
            char *end, struct tm *tm, time_t now)
{
  struct tm now_tm;
  struct tm *refuse_future;
  long num2, num3;

  num2 = strtol(end+1, &end, 10);
  num3 = -1;
  if (*end == c && isdigit(end[1]))
    num3 = strtol(end+1, &end, 10);

  /* Time? Date? */
  switch (c) {
  case ':':
    if (num3 < 0)
      num3 = 0;
    if (set_time(num, num2, num3, tm) == 0) {
      /*
       * If %H:%M:%S was just parsed followed by: .<num4>
       * Consider (& discard) it as fractional second
       * if %Y%m%d is parsed before.
       */
      if (*end == '.' && isdigit(end[1]) && is_date_known(tm))
        strtol(end + 1, &end, 10);
      break;
    }
    return 0;

  case '-':
  case '/':
  case '.':
    if (!now)
      now = time(NULL);
    refuse_future = NULL;
    if (gmtime_r(&now, &now_tm))
      refuse_future = &now_tm;

    if (num > 70) {
      /* yyyy-mm-dd? */
      if (set_date(num, num2, num3, NULL, now, tm) == 0)
        break;
      /* yyyy-dd-mm? */
      if (set_date(num, num3, num2, NULL, now, tm) == 0)
        break;
    }
    /* Our eastern European friends say dd.mm.yy[yy]
     * is the norm there, so giving precedence to
     * mm/dd/yy[yy] form only when separator is not '.'
     */
    if (c != '.' &&
        set_date(num3, num, num2, refuse_future, now, tm) == 0)
      break;
    /* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
    if (set_date(num3, num2, num, refuse_future, now, tm) == 0)
      break;
    /* Funny European mm.dd.yy */
    if (c == '.' &&
        set_date(num3, num, num2, refuse_future, now, tm) == 0)
      break;
    return 0;
  }
  return end - date;
}

/*
 * Have we filled in any part of the time/date yet?
 * We just do a binary 'and' to see if the sign bit
 * is set in all the values.
 */
static inline int nodate(struct tm *tm)
{
  return (tm->tm_year &
    tm->tm_mon &
    tm->tm_mday &
    tm->tm_hour &
    tm->tm_min &
    tm->tm_sec) < 0;
}

/*
 * Have we seen an ISO-8601-alike date, i.e. 20220101T0,
 * In which, hour is still unset,
 * and minutes and second has been set to 0.
 */
static inline int maybeiso8601(struct tm *tm)
{
  return tm->tm_hour == -1 &&
    tm->tm_min == 0 &&
    tm->tm_sec == 0;
}

/*
 * We've seen a digit. Time? Year? Date?
 */
static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt)
{
  int n;
  char *end;
  timestamp_t num;

  num = parse_timestamp(date, &end, 10);

  /*
   * Seconds since 1970? We trigger on that for any numbers with
   * more than 8 digits. This is because we don't want to rule out
   * numbers like 20070606 as a YYYYMMDD date.
   */
  if (num >= 100000000 && nodate(tm)) {
    time_t time = num;
    if (gmtime_r(&time, tm)) {
      *tm_gmt = 1;
      return end - date;
    }
  }

  /*
   * Check for special formats: num[-.:/]num[same]num
   */
  switch (*end) {
  case ':':
  case '.':
  case '/':
  case '-':
    if (isdigit(end[1])) {
      int match = match_multi_number(num, *end, date, end, tm, 0);
      if (match)
        return match;
    }
  }

  /*
   * None of the special formats? Try to guess what
   * the number meant. We use the number of digits
   * to make a more educated guess..
   */
  n = 0;
  do {
    n++;
  } while (isdigit(date[n]));

  /* 8 digits, compact style of ISO-8601's date: YYYYmmDD */
  /* 6 digits, compact style of ISO-8601's time: HHMMSS */
  if (n == 8 || n == 6) {
    unsigned int num1 = num / 10000;
    unsigned int num2 = (num % 10000) / 100;
    unsigned int num3 = num % 100;
    if (n == 8)
      set_date(num1, num2, num3, NULL, time(NULL), tm);
    else if (n == 6 && set_time(num1, num2, num3, tm) == 0 &&
       *end == '.' && isdigit(end[1]))
      strtoul(end + 1, &end, 10);
    return end - date;
  }

  /* reduced precision of ISO-8601's time: HHMM or HH */
  if (maybeiso8601(tm)) {
    unsigned int num1 = num;
    unsigned int num2 = 0;
    if (n == 4) {
      num1 = num / 100;
      num2 = num % 100;
    }
    if ((n == 4 || n == 2) && !nodate(tm) &&
        set_time(num1, num2, 0, tm) == 0)
      return n;
    /*
     * We thought this is an ISO-8601 time string,
     * we set minutes and seconds to 0,
     * turn out it isn't, rollback the change.
     */
    tm->tm_min = tm->tm_sec = -1;
  }

  /* Four-digit year or a timezone? */
  if (n == 4) {
    if (num <= 1400 && *offset == -1) {
      unsigned int minutes = num % 100;
      unsigned int hours = num / 100;
      *offset = hours*60 + minutes;
    } else if (num > 1900 && num < 2100)
      tm->tm_year = num - 1900;
    return n;
  }

  /*
   * Ignore lots of numerals. We took care of 4-digit years above.
   * Days or months must be one or two digits.
   */
  if (n > 2)
    return n;

  /*
   * NOTE! We will give precedence to day-of-month over month or
   * year numbers in the 1-12 range. So 05 is always "mday 5",
   * unless we already have a mday..
   *
   * IOW, 01 Apr 05 parses as "April 1st, 2005".
   */
  if (num > 0 && num < 32 && tm->tm_mday < 0) {
    tm->tm_mday = num;
    return n;
  }

  /* Two-digit year? */
  if (n == 2 && tm->tm_year < 0) {
    if (num < 10 && tm->tm_mday >= 0) {
      tm->tm_year = num + 100;
      return n;
    }
    if (num >= 70) {
      tm->tm_year = num;
      return n;
    }
  }

  if (num > 0 && num < 13 && tm->tm_mon < 0)
    tm->tm_mon = num-1;

  return n;
}

static int match_tz(const char *date, int *offp)
{
  char *end;
  int hour = strtoul(date + 1, &end, 10);
  int n = end - (date + 1);
  int min = 0;

  if (n == 4) {
    /* hhmm */
    min = hour % 100;
    hour = hour / 100;
  } else if (n != 2) {
    min = 99; /* random crap */
  } else if (*end == ':') {
    /* hh:mm? */
    min = strtoul(end + 1, &end, 10);
    if (end - (date + 1) != 5)
      min = 99; /* random crap */
  } /* otherwise we parsed "hh" */

  /*
   * Don't accept any random crap. Even though some places have
   * offset larger than 12 hours (e.g. Pacific/Kiritimati is at
   * UTC+14), there is something wrong if hour part is much
   * larger than that. We might also want to check that the
   * minutes are divisible by 15 or something too. (Offset of
   * Kathmandu, Nepal is UTC+5:45)
   */
  if (min < 60 && hour < 24) {
    int offset = hour * 60 + min;
    if (*date == '-')
      offset = -offset;
    *offp = offset;
  }
  return end - date;
}

static void date_string(timestamp_t date, int offset, struct strbuf *buf)
{
  int sign = '+';

  if (offset < 0) {
    offset = -offset;
    sign = '-';
  }
  strbuf_addf(buf, "%"PRItime" %c%02d%02d", date, sign, offset / 60, offset % 60);
}

/*
 * Parse a string like "0 +0000" as ancient timestamp near epoch, but
 * only when it appears not as part of any other string.
 */
static int match_object_header_date(const char *date, timestamp_t *timestamp, int *offset)
{
  char *end;
  timestamp_t stamp;
  int ofs;

  if (*date < '0' || '9' < *date)
    return -1;
  stamp = parse_timestamp(date, &end, 10);
  if (*end != ' ' || stamp == TIME_MAX || (end[1] != '+' && end[1] != '-'))
    return -1;
  date = end + 2;
  ofs = strtol(date, &end, 10);
  if ((*end != '\0' && (*end != '\n')) || end != date + 4)
    return -1;
  ofs = (ofs / 100) * 60 + (ofs % 100);
  if (date[-1] == '-')
    ofs = -ofs;
  *timestamp = stamp;
  *offset = ofs;
  return 0;
}


/* timestamp of 2099-12-31T23:59:59Z, including 32 leap days */
static const timestamp_t timestamp_max = (((timestamp_t)2100 - 1970) * 365 + 32) * 24 * 60 * 60 - 1;

/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
   (i.e. English) day/month names, and it doesn't work correctly with %z. */
int parse_date_basic(const char *date, timestamp_t *timestamp, int *offset)
{
  struct tm tm;
  int tm_gmt;
  timestamp_t dummy_timestamp;
  int dummy_offset;

  if (!timestamp)
    timestamp = &dummy_timestamp;
  if (!offset)
    offset = &dummy_offset;

  memset(&tm, 0, sizeof(tm));
  tm.tm_year = -1;
  tm.tm_mon = -1;
  tm.tm_mday = -1;
  tm.tm_isdst = -1;
  tm.tm_hour = -1;
  tm.tm_min = -1;
  tm.tm_sec = -1;
  *offset = -1;
  tm_gmt = 0;

  if (*date == '@' &&
      !match_object_header_date(date + 1, timestamp, offset))
    return 0; /* success */
  for (;;) {
    int match = 0;
    unsigned char c = *date;

    /* Stop at end of string or newline */
    if (!c || c == '\n')
      break;

    if (isalpha(c))
      match = match_alpha(date, &tm, offset);
    else if (isdigit(c))
      match = match_digit(date, &tm, offset, &tm_gmt);
    else if ((c == '-' || c == '+') && isdigit(date[1]))
      match = match_tz(date, offset);

    if (!match) {
      /* BAD CRAP */
      match = 1;
    }

    date += match;
  }

  /* do not use mktime(), which uses local timezone, here */
  *timestamp = tm_to_time_t(&tm);
  if (*timestamp == -1)
    return -1;

  if (*offset == -1) {
    time_t temp_time;

    /* gmtime_r() in match_digit() may have clobbered it */
    tm.tm_isdst = -1;
    temp_time = mktime(&tm);
    if ((time_t)*timestamp > temp_time) {
      *offset = ((time_t)*timestamp - temp_time) / 60;
    } else {
      *offset = -(int)((temp_time - (time_t)*timestamp) / 60);
    }
  }

  if (!tm_gmt) {
    if (*offset > 0 && *offset * 60 > *timestamp)
      return -1;
    if (*offset < 0 && -*offset * 60 > timestamp_max - *timestamp)
      return -1;
    *timestamp -= *offset * 60;
  }

  return 0; /* success */
}

int parse_expiry_date(const char *date, timestamp_t *timestamp)
{
  int errors = 0;

  if (!strcmp(date, "never") || !strcmp(date, "false"))
    *timestamp = 0;
  else if (!strcmp(date, "all") || !strcmp(date, "now"))
    /*
     * We take over "now" here, which usually translates
     * to the current timestamp.  This is because the user
     * really means to expire everything that was done in
     * the past, and by definition reflogs are the record
     * of the past, and there is nothing from the future
     * to be kept.
     */
    *timestamp = TIME_MAX;
  else
    *timestamp = approxidate_careful(date, &errors);

  return errors;
}

int parse_date(const char *date, struct strbuf *result)
{
  timestamp_t timestamp;
  int offset;
  if (parse_date_basic(date, &timestamp, &offset))
    return -1;
  date_string(timestamp, offset, result);
  return 0;
}

static enum date_mode_type parse_date_type(const char *format, const char **end)
{
  if (skip_prefix(format, "relative", end))
    return DATE_RELATIVE;
  if (skip_prefix(format, "iso8601-strict", end) ||
      skip_prefix(format, "iso-strict", end))
    return DATE_ISO8601_STRICT;
  if (skip_prefix(format, "iso8601", end) ||
      skip_prefix(format, "iso", end))
    return DATE_ISO8601;
  if (skip_prefix(format, "rfc2822", end) ||
      skip_prefix(format, "rfc", end))
    return DATE_RFC2822;
  if (skip_prefix(format, "short", end))
    return DATE_SHORT;
  if (skip_prefix(format, "default", end))
    return DATE_NORMAL;
  if (skip_prefix(format, "human", end))
    return DATE_HUMAN;
  if (skip_prefix(format, "raw", end))
    return DATE_RAW;
  if (skip_prefix(format, "unix", end))
    return DATE_UNIX;
  if (skip_prefix(format, "format", end))
    return DATE_STRFTIME;
  /*
   * Please update $__git_log_date_formats in
   * git-completion.bash when you add new formats.
   */

  die("unknown date format %s", format);
}

void parse_date_format(const char *format, struct date_mode *mode)
{
  const char *p;

  /* "auto:foo" is "if tty/pager, then foo, otherwise normal" */
  if (skip_prefix(format, "auto:", &p)) {
    if (isatty(1) || pager_in_use())
      format = p;
    else
      format = "default";
  }

  /* historical alias */
  if (!strcmp(format, "local"))
    format = "default-local";

  mode->type = parse_date_type(format, &p);
  mode->local = 0;

  if (skip_prefix(p, "-local", &p))
    mode->local = 1;

  if (mode->type == DATE_STRFTIME) {
    if (!skip_prefix(p, ":", &p))
      die("date format missing colon separator: %s", format);
    mode->strftime_fmt = xstrdup(p);
  } else if (*p)
    die("unknown date format %s", format);
}

void date_mode_release(struct date_mode *mode)
{
  free((char *)mode->strftime_fmt);
}

void datestamp(struct strbuf *out)
{
  time_t now;
  int offset;
  struct tm tm = { 0 };

  time(&now);

  offset = tm_to_time_t(localtime_r(&now, &tm)) - now;
  offset /= 60;

  date_string(now, offset, out);
}

/*
 * Relative time update (eg "2 days ago").  If we haven't set the time
 * yet, we need to set it from current time.
 */
static time_t update_tm(struct tm *tm, struct tm *now, time_t sec)
{
  time_t n;

  if (tm->tm_mday < 0)
    tm->tm_mday = now->tm_mday;
  if (tm->tm_mon < 0)
    tm->tm_mon = now->tm_mon;
  if (tm->tm_year < 0) {
    tm->tm_year = now->tm_year;
    if (tm->tm_mon > now->tm_mon)
      tm->tm_year--;
  }

  n = mktime(tm) - sec;
  localtime_r(&n, tm);
  return n;
}

/*
 * Do we have a pending number at the end, or when
 * we see a new one? Let's assume it's a month day,
 * as in "Dec 6, 1992"
 */
static void pending_number(struct tm *tm, int *num)
{
  int number = *num;

  if (number) {
    *num = 0;
    if (tm->tm_mday < 0 && number < 32)
      tm->tm_mday = number;
    else if (tm->tm_mon < 0 && number < 13)
      tm->tm_mon = number-1;
    else if (tm->tm_year < 0) {
      if (number > 1969 && number < 2100)
        tm->tm_year = number - 1900;
      else if (number > 69 && number < 100)
        tm->tm_year = number;
      else if (number < 38)
        tm->tm_year = 100 + number;
      /* We screw up for number = 00 ? */
    }
  }
}

static void date_now(struct tm *tm, struct tm *now, int *num)
{
  *num = 0;
  update_tm(tm, now, 0);
}

static void date_yesterday(struct tm *tm, struct tm *now, int *num)
{
  *num = 0;
  update_tm(tm, now, 24*60*60);
}

static void date_time(struct tm *tm, struct tm *now, int hour)
{
  if (tm->tm_hour < hour)
    update_tm(tm, now, 24*60*60);
  tm->tm_hour = hour;
  tm->tm_min = 0;
  tm->tm_sec = 0;
}

static void date_midnight(struct tm *tm, struct tm *now, int *num)
{
  pending_number(tm, num);
  date_time(tm, now, 0);
}

static void date_noon(struct tm *tm, struct tm *now, int *num)
{
  pending_number(tm, num);
  date_time(tm, now, 12);
}

static void date_tea(struct tm *tm, struct tm *now, int *num)
{
  pending_number(tm, num);
  date_time(tm, now, 17);
}

static void date_pm(struct tm *tm, struct tm *now UNUSED, int *num)
{
  int hour, n = *num;
  *num = 0;

  hour = tm->tm_hour;
  if (n) {
    hour = n;
    tm->tm_min = 0;
    tm->tm_sec = 0;
  }
  tm->tm_hour = (hour % 12) + 12;
}

static void date_am(struct tm *tm, struct tm *now UNUSED, int *num)
{
  int hour, n = *num;
  *num = 0;

  hour = tm->tm_hour;
  if (n) {
    hour = n;
    tm->tm_min = 0;
    tm->tm_sec = 0;
  }
  tm->tm_hour = (hour % 12);
}

static void date_never(struct tm *tm, struct tm *now UNUSED, int *num)
{
  time_t n = 0;
  localtime_r(&n, tm);
  *num = 0;
}

static const struct special {
  const char *name;
  void (*fn)(struct tm *, struct tm *, int *);
} special[] = {
  { "yesterday", date_yesterday },
  { "noon", date_noon },
  { "midnight", date_midnight },
  { "tea", date_tea },
  { "PM", date_pm },
  { "AM", date_am },
  { "never", date_never },
  { "now", date_now },
  { NULL }
};

static const char *number_name[] = {
  "zero", "one", "two", "three", "four",
  "five", "six", "seven", "eight", "nine", "ten",
};

static const struct typelen {
  const char *type;
  int length;
} typelen[] = {
  { "seconds", 1 },
  { "minutes", 60 },
  { "hours", 60*60 },
  { "days", 24*60*60 },
  { "weeks", 7*24*60*60 },
  { NULL }
};

static const char *approxidate_alpha(const char *date, struct tm *tm, struct tm *now, int *num, int *touched)
{
  const struct typelen *tl;
  const struct special *s;
  const char *end = date;
  int i;

  while (isalpha(*++end))
    ;

  for (i = 0; i < 12; i++) {
    int match = match_string(date, month_names[i]);
    if (match >= 3) {
      tm->tm_mon = i;
      *touched = 1;
      return end;
    }
  }

  for (s = special; s->name; s++) {
    size_t len = strlen(s->name);
    if (match_string(date, s->name) == len) {
      s->fn(tm, now, num);
      *touched = 1;
      return end;
    }
  }

  if (!*num) {
    for (i = 1; i < 11; i++) {
      size_t len = strlen(number_name[i]);
      if (match_string(date, number_name[i]) == len) {
        *num = i;
        *touched = 1;
        return end;
      }
    }
    if (match_string(date, "last") == 4) {
      *num = 1;
      *touched = 1;
    }
    return end;
  }

  tl = typelen;
  while (tl->type) {
    size_t len = strlen(tl->type);
    if (match_string(date, tl->type) >= len-1) {
      update_tm(tm, now, tl->length * *num);
      *num = 0;
      *touched = 1;
      return end;
    }
    tl++;
  }

  for (i = 0; i < 7; i++) {
    int match = match_string(date, weekday_names[i]);
    if (match >= 3) {
      int diff, n = *num -1;
      *num = 0;

      diff = tm->tm_wday - i;
      if (diff <= 0)
        n++;
      diff += 7*n;

      update_tm(tm, now, diff * 24 * 60 * 60);
      *touched = 1;
      return end;
    }
  }

  if (match_string(date, "months") >= 5) {
    int n;
    update_tm(tm, now, 0); /* fill in date fields if needed */
    n = tm->tm_mon - *num;
    *num = 0;
    while (n < 0) {
      n += 12;
      tm->tm_year--;
    }
    tm->tm_mon = n;
    *touched = 1;
    return end;
  }

  if (match_string(date, "years") >= 4) {
    update_tm(tm, now, 0); /* fill in date fields if needed */
    tm->tm_year -= *num;
    *num = 0;
    *touched = 1;
    return end;
  }

  return end;
}

static const char *approxidate_digit(const char *date, struct tm *tm, int *num,
             time_t now)
{
  char *end;
  timestamp_t number = parse_timestamp(date, &end, 10);

  switch (*end) {
  case ':':
  case '.':
  case '/':
  case '-':
    if (isdigit(end[1])) {
      int match = match_multi_number(number, *end, date, end,
                   tm, now);
      if (match)
        return date + match;
    }
  }

  /* Accept zero-padding only for small numbers ("Dec 02", never "Dec 0002") */
  if (date[0] != '0' || end - date <= 2)
    *num = number;
  return end;
}

static timestamp_t approxidate_str(const char *date,
           const struct timeval *tv,
           int *error_ret)
{
  int number = 0;
  int touched = 0;
  struct tm tm, now;
  time_t time_sec;

  time_sec = tv->tv_sec;
  localtime_r(&time_sec, &tm);
  now = tm;

  tm.tm_year = -1;
  tm.tm_mon = -1;
  tm.tm_mday = -1;

  for (;;) {
    unsigned char c = *date;
    if (!c)
      break;
    date++;
    if (isdigit(c)) {
      pending_number(&tm, &number);
      date = approxidate_digit(date-1, &tm, &number, time_sec);
      touched = 1;
      continue;
    }
    if (isalpha(c))
      date = approxidate_alpha(date-1, &tm, &now, &number, &touched);
  }
  pending_number(&tm, &number);
  if (!touched)
    *error_ret = 1;
  return (timestamp_t)update_tm(&tm, &now, 0);
}

timestamp_t approxidate_careful(const char *date, int *error_ret)
{
  struct timeval tv;
  timestamp_t timestamp;
  int offset;
  int dummy = 0;
  if (!error_ret)
    error_ret = &dummy;

  if (!parse_date_basic(date, &timestamp, &offset)) {
    *error_ret = 0;
    return timestamp;
  }

  get_time(&tv);
  return approxidate_str(date, &tv, error_ret);
}

int date_overflows(timestamp_t t)
{
  time_t sys;

  /* If we overflowed our timestamp data type, that's bad... */
  if ((uintmax_t)t >= TIME_MAX)
    return 1;

  /*
   * ...but we also are going to feed the result to system
   * functions that expect time_t, which is often "signed long".
   * Make sure that we fit into time_t, as well.
   */
  sys = t;
  return t != sys || (t < 1) != (sys < 1);
}

Coverage Report

Created: 2026-01-09 07:10