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[PATCH v5 3/4] date.c: skip fractional second part of ISO-8601

From
Đoàn Trần Công Danh <congdanhqx@gmail.com>
Date
Apr 24, 2020, 15:07 UTC
Message-ID
<f21aa2dcf507f9eb13a623b6718a170d2661f15d.1587740682.git.congdanhqx@gmail.com>
In-Reply-To
<cover.1587740682.git.congdanhqx@gmail.com>
git-commit(1) says ISO-8601 is one of our supported date format.

ISO-8601 allows timestamps to have a fractional number of seconds. We represent time only in terms of whole seconds, so we never bothered parsing fractional seconds. However, it's better for us to parse and throw away the fractional part than to refuse to parse the timestamp at all.

And refusing parsing fractional second part may confuse the parse to think fractional and timezone as day and month in this example:

	2008-02-14 20:30:45.019-04:00

While doing this, make sure that we only interpret the number after the second and the dot as fractional when and only when the date is known, since only ISO-8601 allows the fractional part, and we've taught our users to interpret "12:34:56.7.days.ago" as a way to specify a time relative to current time.

Reported-by: Brian M. Carlson <sandals@crustytoothpaste.net>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 Documentation/date-formats.txt |  5 ++++-
 date.c                         | 12 ++++++++++++
 t/t0006-date.sh                |  3 +++
 3 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/Documentation/date-formats.txt b/Documentation/date-formats.txt
index 6926e0a4c8..7e7eaba643 100644
--- a/Documentation/date-formats.txt
+++ b/Documentation/date-formats.txt
@@ -20,7 +20,10 @@ RFC 2822::
 ISO 8601::
 	Time and date specified by the ISO 8601 standard, for example
 	`2005-04-07T22:13:13`. The parser accepts a space instead of the
-	`T` character as well.
+	`T` character as well. Fractional parts of a second will be ignored,
+	for example `2005-04-07T22:13:13.019` will be treated as
+	`2005-04-07T22:13:13`
+
 +
 NOTE: In addition, the date part is accepted in the following formats:
 `YYYY.MM.DD`, `MM/DD/YYYY` and `DD.MM.YYYY`.
diff --git a/date.c b/date.c
index fa39e5e8a5..2c9071d53f 100644
--- a/date.c
+++ b/date.c
@@ -553,6 +553,11 @@ static int set_time(long hour, long minute, long second, struct tm *tm)
 	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)
 {
@@ -571,6 +576,13 @@ static int match_multi_number(timestamp_t num, char c, const char *date,
 		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;
diff --git a/t/t0006-date.sh b/t/t0006-date.sh
index d9fcc829a9..80917c81c3 100755
--- a/t/t0006-date.sh
+++ b/t/t0006-date.sh
@@ -81,6 +81,8 @@ check_parse 2008-02 bad
 check_parse 2008-02-14 bad
 check_parse '2008-02-14 20:30:45' '2008-02-14 20:30:45 +0000'
 check_parse '2008-02-14 20:30:45 -0500' '2008-02-14 20:30:45 -0500'
+check_parse '2008.02.14 20:30:45 -0500' '2008-02-14 20:30:45 -0500'
+check_parse '2008-02-14 20:30:45.019-04:00' '2008-02-14 20:30:45 -0400'
 check_parse '2008-02-14 20:30:45 -0015' '2008-02-14 20:30:45 -0015'
 check_parse '2008-02-14 20:30:45 -5' '2008-02-14 20:30:45 +0000'
 check_parse '2008-02-14 20:30:45 -5:' '2008-02-14 20:30:45 +0000'
@@ -103,6 +105,7 @@ check_approxidate 5.seconds.ago '2009-08-30 19:19:55'
 check_approxidate 10.minutes.ago '2009-08-30 19:10:00'
 check_approxidate yesterday '2009-08-29 19:20:00'
 check_approxidate 3.days.ago '2009-08-27 19:20:00'
+check_approxidate '12:34:56.3.days.ago' '2009-08-27 12:34:56'
 check_approxidate 3.weeks.ago '2009-08-09 19:20:00'
 check_approxidate 3.months.ago '2009-05-30 19:20:00'
 check_approxidate 2.years.3.months.ago '2007-05-30 19:20:00'

-- 
2.26.2.384.g435bf60bd5
Previous: Đoàn Trần Công DanhNext: Đoàn Trần Công Danh
Message 48 of 49 in “Mishandling of fractional seconds in ISO 8601 format”
  1. brian m. carlsonApr 14, 2020
  2. 0/2 More ISO-8601 supportĐoàn Trần Công Danh, Apr 14, 2020
  3. 1/2 date.c: allow fractional second part of ISO-8601Đoàn Trần Công Danh, Apr 14, 2020
  4. Jeff KingApr 14, 2020
  5. Danh DoanApr 15, 2020
  6. Jeff KingApr 14, 2020
  7. brian m. carlsonApr 14, 2020
  8. Danh DoanApr 15, 2020
  9. 2/2 date.c: allow compact version of ISO-8601 datetimeĐoàn Trần Công Danh, Apr 14, 2020
  10. Jeff KingApr 14, 2020
  11. Danh DoanApr 15, 2020
  12. Junio C HamanoApr 15, 2020
  13. Jeff KingApr 15, 2020
  14. Junio C HamanoApr 15, 2020
  15. Danh DoanApr 16, 2020
  16. brian m. carlsonApr 14, 2020
  17. 0/2 More ISO-8601 supportĐoàn Trần Công Danh, Apr 15, 2020
  18. 1/2 date.c: skip fractional second part of ISO-8601Đoàn Trần Công Danh, Apr 15, 2020
  19. Torsten BögershausenApr 15, 2020
  20. Danh DoanApr 16, 2020
  21. 2/2 date.c: allow compact version of ISO-8601 datetimeĐoàn Trần Công Danh, Apr 15, 2020
  22. 0/2 More ISO-8601 supportĐoàn Trần Công Danh, Apr 22, 2020
  23. 1/2 date.c: skip fractional second part of ISO-8601Đoàn Trần Công Danh, Apr 22, 2020
  24. Junio C HamanoApr 22, 2020
  25. Danh DoanApr 23, 2020
  26. Junio C HamanoApr 23, 2020
  27. Philip OakleyApr 23, 2020
  28. Danh DoanApr 24, 2020
  29. Junio C HamanoApr 24, 2020
  30. Philip OakleyApr 24, 2020
  31. Philip OakleyApr 24, 2020
  32. 2/2 date.c: allow compact version of ISO-8601 datetimeĐoàn Trần Công Danh, Apr 22, 2020
  33. Junio C HamanoApr 22, 2020
  34. Danh DoanApr 23, 2020
  35. 0/4 More ISO-8601 supportĐoàn Trần Công Danh, Apr 23, 2020
  36. 1/4 date.c: s/is_date/set_date/Đoàn Trần Công Danh, Apr 23, 2020
  37. Junio C HamanoApr 23, 2020
  38. 2/4 date.c: validate and set time in a helper functionĐoàn Trần Công Danh, Apr 23, 2020
  39. Junio C HamanoApr 23, 2020
  40. Danh DoanApr 24, 2020
  41. Junio C HamanoApr 24, 2020
  42. 3/4 date.c: skip fractional second part of ISO-8601Đoàn Trần Công Danh, Apr 23, 2020
  43. Junio C HamanoApr 23, 2020
  44. 4/4 date.c: allow compact version of ISO-8601 datetimeĐoàn Trần Công Danh, Apr 23, 2020
  45. 0/4 More ISO-8601 supportĐoàn Trần Công Danh, Apr 24, 2020
  46. 1/4 date.c: s/is_date/set_date/Đoàn Trần Công Danh, Apr 24, 2020
  47. 2/4 date.c: validate and set time in a helper functionĐoàn Trần Công Danh, Apr 24, 2020
  48. 3/4 date.c: skip fractional second part of ISO-8601Đoàn Trần Công Danh, Apr 24, 2020
  49. 4/4 date.c: allow compact version of ISO-8601 datetimeĐoàn Trần Công Danh, Apr 24, 2020

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