diff mbox series

[v4,3/4] date.c: skip fractional second part of ISO-8601

Message ID 8b18d0ee5d6f08394e54e16ca7618c687791a509.1587644889.git.congdanhqx@gmail.com (mailing list archive)
State New, archived
Headers show
Series More ISO-8601 support | expand

Commit Message

Đoàn Trần Công Danh April 23, 2020, 1:52 p.m. UTC 
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>
Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 Documentation/date-formats.txt | 5 ++++-
 date.c                         | 8 +++++++-
 t/t0006-date.sh                | 3 +++
 3 files changed, 14 insertions(+), 2 deletions(-)

Comments

Junio C Hamano April 23, 2020, 8:29 p.m. UTC | #1 
Đoàn Trần Công Danh  <congdanhqx@gmail.com> writes:

> -		if (num3 < 0)
> +		if (num3 < 0) {
>  			num3 = 0;
> +		} else if (*end == '.' && isdigit(end[1]) &&
> +			   tm->tm_year != -1 && tm->tm_mon != -1 && tm->tm_mday != -1 &&
> +			   set_time(num, num2, num3, tm) == 0) {
> +			/* %Y%m%d is known, ignore fractional <num4> in HHMMSS.<num4> */
> +			strtol(end + 1, &end, 10);
> +		}
>  		if (set_time(num, num2, num3, tm) == 0)

Hmmm.  

While calling set_time() on the same 4-tuple might be idempotent
when it succeeds, the call with a potential new side effect in the
conditional part leaves a bad taste in my mouth.

I am wondering if the follwoing would be a more readable
alternative.

 date.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/date.c b/date.c
index f5d5a91208..3eb9b6032c 100644
--- a/date.c
+++ b/date.c
@@ -572,8 +572,16 @@ static int match_multi_number(timestamp_t num, char c, const char *date,
 	case ':':
 		if (num3 < 0)
 			num3 = 0;
-		if (set_time(num, num2, num3, tm) == 0)
+		if (set_time(num, num2, num3, tm) == 0) {
+			/* 
+			 * Is the "HH:MM:SS" we just parsed followed by
+			 *  ".<num4>" (fractinal second)?  Discard it
+			 * only when we already have YY/MM/DD.
+			 */
+			if (*end == '.' && isdigit(end[1]) && date_known(tm))
+				(void) strtol(end + 1, &end, 10);
 			break;
+		}
 		return 0;
 
 	case '-':
diff mbox series

Patch

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 f5d5a91208..5d635031e0 100644
--- a/date.c
+++ b/date.c
@@ -570,8 +570,14 @@  static int match_multi_number(timestamp_t num, char c, const char *date,
 	/* Time? Date? */
 	switch (c) {
 	case ':':
-		if (num3 < 0)
+		if (num3 < 0) {
 			num3 = 0;
+		} else if (*end == '.' && isdigit(end[1]) &&
+			   tm->tm_year != -1 && tm->tm_mon != -1 && tm->tm_mday != -1 &&
+			   set_time(num, num2, num3, tm) == 0) {
+			/* %Y%m%d is known, ignore fractional <num4> in HHMMSS.<num4> */
+			strtol(end + 1, &end, 10);
+		}
 		if (set_time(num, num2, num3, tm) == 0)
 			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'