merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

1 files changed, 1335 insertions, 0 deletions

diff --git a/third_party/git/date.c b/third_party/git/date.c
new file mode 100644
index 000000000000..8126146c5069
--- /dev/null
+++ b/third_party/git/date.c
@@ -0,0 +1,1335 @@
+/*
+ * GIT - The information manager from hell
+ *
+ * Copyright (C) Linus Torvalds, 2005
+ */
+
+#include "cache.h"
+
+/*
+ * This is like mktime, but without normalization of tm_wday and tm_yday.
+ */
+static 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)
+{
+	time_t t = gm_time_t(time, tz);
+	return gmtime(&t);
+}
+
+static struct tm *time_to_tm_local(timestamp_t time)
+{
+	time_t t = time;
+	return localtime(&t);
+}
+
+/*
+ * 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,
+			const struct timeval *now,
+			struct strbuf *timebuf)
+{
+	timestamp_t diff;
+	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)
+{
+	static struct date_mode mode;
+	if (type == DATE_STRFTIME)
+		BUG("cannot create anonymous strftime date_mode struct");
+	mode.type = type;
+	mode.local = 0;
+	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) {
+		struct timeval now;
+		get_time(&now);
+		show_date_relative(time, &now, 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, const struct date_mode *mode)
+{
+	struct tm *tm;
+	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) {
+		struct timeval now;
+
+		strbuf_reset(&timebuf);
+		get_time(&now);
+		show_date_relative(time, &now, &timebuf);
+		return timebuf.buf;
+	}
+
+	if (mode->local)
+		tm = time_to_tm_local(time);
+	else
+		tm = time_to_tm(time, tz);
+	if (!tm) {
+		tm = time_to_tm(0, 0);
+		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) {
+		char sign = (tz >= 0) ? '+' : '-';
+		tz = abs(tz);
+		strbuf_addf(&timebuf, "%04d-%02d-%02dT%02d:%02d:%02d%c%02d:%02d",
+				tm->tm_year + 1900,
+				tm->tm_mon + 1,
+				tm->tm_mday,
+				tm->tm_hour, tm->tm_min, tm->tm_sec,
+				sign, 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;
+	}
+
+	/* BAD CRAP */
+	return skip_alpha(date);
+}
+
+static int is_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 0;
+		if (!now_tm)
+			return 1;
+
+		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 0;
+		tm->tm_mon = r->tm_mon;
+		tm->tm_mday = r->tm_mday;
+		if (year != -1)
+			tm->tm_year = r->tm_year;
+		return 1;
+	}
+	return 0;
+}
+
+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 (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
+			tm->tm_hour = num;
+			tm->tm_min = num2;
+			tm->tm_sec = num3;
+			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 (is_date(num, num2, num3, NULL, now, tm))
+				break;
+			/* yyyy-dd-mm? */
+			if (is_date(num, num3, num2, NULL, now, tm))
+				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 != '.' &&
+		    is_date(num3, num, num2, refuse_future, now, tm))
+			break;
+		/* European dd.mm.yy[yy] or funny US dd/mm/yy[yy] */
+		if (is_date(num3, num2, num, refuse_future, now, tm))
+			break;
+		/* Funny European mm.dd.yy */
+		if (c == '.' &&
+		    is_date(num3, num, num2, refuse_future, now, tm))
+			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;
+}
+
+/*
+ * 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]));
+
+	/* 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;
+}
+
+/* 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)
+		*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 she has 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 datestamp(struct strbuf *out)
+{
+	time_t now;
+	int offset;
+
+	time(&now);
+
+	offset = tm_to_time_t(localtime(&now)) - 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, 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, 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, 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++) {
+		int 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++) {
+			int 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) {
+		int 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_relative(const char *date, const struct timeval *tv)
+{
+	timestamp_t timestamp;
+	int offset;
+	int errors = 0;
+
+	if (!parse_date_basic(date, &timestamp, &offset))
+		return timestamp;
+	return approxidate_str(date, tv, &errors);
+}
+
+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);
+}