threads / patch / 8465

patchAccept dates before 2000/01/01 when specified as seconds since the epoch

Subject: [PATCH] Accept dates before 2000/01/01 when specified as seconds since the epoch

## tl;dr

6 messages between Jun 6, 2007 and Jun 7, 2007. Diffs are folded; open one to read it.

replies: 5people: 4as markdown or json

Johannes Sixt· Jun 6, 2007, 08:11 UTC · lore

Tests with git-filter-branch on a repository that was converted from CVS and that has commits reaching back to 1999 revealed that it is necessary to parse dates before 2000/01/01 when they are specified as seconds since 1970/01/01. There is now still a limit, 100000000, which is 1973/03/03 09:46:40 UTC, in order to allow that dates are represented as 8 digits.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
---
 date.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
Show changes to date.c +4 −2
diff --git a/date.c b/date.c
index a9b59a2..4690371 100644
--- a/date.c
+++ b/date.c
@@ -414,9 +414,11 @@ static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt
 	num = strtoul(date, &end, 10);
 
 	/*
-	 * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
+	 * 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 > 946684800) {
+	if (num >= 100000000) {
 		time_t time = num;
 		if (gmtime_r(&time, tm)) {
 			*tm_gmt = 1;

-- 
1.5.2.1.120.gd732
Junio C Hamano· Jun 6, 2007, 08:29 UTC · re: Johannes Sixt · lore

Re: [PATCH] Accept dates before 2000/01/01 when specified as seconds since the epoch

I vaguely recall hitting the same issue soon after date.c was done, and sending in a patch in the same spirit but with different implementation (I essentially duplicated that "seconds since epoch" without any cutoff as the last ditch fallback) long time ago (this was before I took git over; the patch was rejected).

It almost makes me wonder if it is better to introduce a special syntax to denote "seconds since epoch plus timezone offset" for our Porcelain use, instead of keeping this arbitrary cut-off date which nobody can agree on and which forces us to roll back from time to time. For one thing, such a syntax would allow us to talk about a timestamp before the epoch.

Perhaps
	"epoch" [-+] [0-9]+ " " [-+][0-9][0-9][0-9][0-9]
?
Johannes Sixt· Jun 6, 2007, 10:42 UTC · re: Junio C Hamano · lore

Re: [PATCH] Accept dates before 2000/01/01 when specified as seconds since the epoch

Junio C Hamano wrote:
Show 19 quoted lines
> 
> I vaguely recall hitting the same issue soon after date.c was
> done, and sending in a patch in the same spirit but with
> different implementation (I essentially duplicated that "seconds
> since epoch" without any cutoff as the last ditch fallback) long
> time ago (this was before I took git over; the patch was rejected).
> 
> It almost makes me wonder if it is better to introduce a special
> syntax to denote "seconds since epoch plus timezone offset" for
> our Porcelain use, instead of keeping this arbitrary cut-off
> date which nobody can agree on and which forces us to roll back
> from time to time.  For one thing, such a syntax would allow us
> to talk about a timestamp before the epoch.
> 
> Perhaps
> 
>         "epoch" [-+] [0-9]+ " " [-+][0-9][0-9][0-9][0-9]
> 
> ?

OTOH, the previous limit 2000/01/01 was completely arbitrary, while the new limit 100000000secs has some justification: Numbers with fewer digits could be mistaken as dates.

-- Hannes
Sam Vilain· Jun 7, 2007, 05:09 UTC · re: Junio C Hamano · lore

Re: [PATCH] Accept dates before 2000/01/01 when specified as seconds since the epoch

Junio C Hamano wrote:
Show 16 quoted lines
> I vaguely recall hitting the same issue soon after date.c was
> done, and sending in a patch in the same spirit but with
> different implementation (I essentially duplicated that "seconds
> since epoch" without any cutoff as the last ditch fallback) long
> time ago (this was before I took git over; the patch was rejected).
> 
> It almost makes me wonder if it is better to introduce a special
> syntax to denote "seconds since epoch plus timezone offset" for
> our Porcelain use, instead of keeping this arbitrary cut-off
> date which nobody can agree on and which forces us to roll back
> from time to time.  For one thing, such a syntax would allow us
> to talk about a timestamp before the epoch.
> 
> Perhaps
> 
> 	"epoch" [-+] [0-9]+ " " [-+][0-9][0-9][0-9][0-9]

Probably a good idea, though it would break cg-admin-rewritehist. I had to make a similar change when working with the Perl history. Perhaps allow both?

There is a 10 digit ISO forms (YYYYMMDDHH) and a 9 digit form (YYYYDDDHH), but these are very rare :)

Sam.
Junio C Hamano· Jun 7, 2007, 05:29 UTC · re: Sam Vilain · lore

Re: [PATCH] Accept dates before 2000/01/01 when specified as seconds since the epoch

Sam Vilain <sam@vilain.net> writes:
Show 5 quoted lines
>> Perhaps
>> 
>> 	"epoch" [-+] [0-9]+ " " [-+][0-9][0-9][0-9][0-9]
>
> Probably a good idea, though it would break cg-admin-rewritehist.

I was saying "additionally allow that to express timestamp even before the epoch", and existing cg-admin-rewritehist does not feed such a string, so I do not know how the additionally allowed format could break it. Maybe I am missing something?

In any case, "timestamps after March 1973" patch from j6t is a good change independent from the above one.

Johannes Schindelin· Jun 7, 2007, 05:30 UTC · re: Sam Vilain · lore

Re: [PATCH] Accept dates before 2000/01/01 when specified as seconds since the epoch

Hi,
On Thu, 7 Jun 2007, Sam Vilain wrote:
Show 19 quoted lines
> Junio C Hamano wrote:
> > I vaguely recall hitting the same issue soon after date.c was
> > done, and sending in a patch in the same spirit but with
> > different implementation (I essentially duplicated that "seconds
> > since epoch" without any cutoff as the last ditch fallback) long
> > time ago (this was before I took git over; the patch was rejected).
> > 
> > It almost makes me wonder if it is better to introduce a special
> > syntax to denote "seconds since epoch plus timezone offset" for
> > our Porcelain use, instead of keeping this arbitrary cut-off
> > date which nobody can agree on and which forces us to roll back
> > from time to time.  For one thing, such a syntax would allow us
> > to talk about a timestamp before the epoch.
> > 
> > Perhaps
> > 
> > 	"epoch" [-+] [0-9]+ " " [-+][0-9][0-9][0-9][0-9]
> 
> Probably a good idea, though it would break cg-admin-rewritehist.

FWIW I don't think we have to care that much about cg-admin-rewritehist, since it lives on as git-filter-branch, and we can adapt it as we go.

Ciao, Dscho

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