From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: Thomas Bock <bockthom@cs.uni-saarland.de>,
Derrick Stolee <derrickstolee@github.com>,
git@vger.kernel.org
Subject: Re: [PATCH 2/3] parse_commit(): parse timestamp from end of line
Date: Mon, 24 Apr 2023 10:05:42 -0700 [thread overview]
Message-ID: <xmqqcz3tfbx5.fsf@gitster.g> (raw)
In-Reply-To: <20230422134703.GB3942326@coredump.intra.peff.net> (Jeff King's message of "Sat, 22 Apr 2023 09:47:03 -0400")
Jeff King <peff@peff.net> writes:
> To find the committer timestamp, we parse left-to-right looking for the
> closing ">" of the email, and then expect the timestamp right after
> that. But we've seen some broken cases in the wild where this fails, but
> we _could_ find the timestamp with a little extra work. E.g.:
>
> Name <Name<email>> 123456789 -0500
> ...
> So let's use the same trick as 03818a4a94: find the end of the line, and
> parse back to the final ">".
This obviously assumes that even in a broken ident, it is very
likely that the second component (where <e-mail> usually sits) ends
with a '>'. Given that we enclose whatever garbage the end user
gave us as their e-mail inside a pair of <> ourselves, it is a very
sensible assumption, I would think. The original parser assumed
that the end user would not have '>' inside their e-mail part of the
ident, which turns out to be more problematic than the alternative
being proposed. It is doubly good that we already parse from the
end elsewhere.
Nice.
> + /*
> + * parse to end-of-line and then walk backwards, which
> + * handles some malformed cases.
> + */
I would say "parse to" -> "jump to", but technically moving forward
looking for a LF byte is still "parsing". "some" malformed cases
being "most plausible" ones (due to how ident.c::fmt_ident() is what
writes '>' after the string end-user gave as e-mail) may be worth
mentioning.
> + eol = memchr(buf, '\n', tail - buf);
> + if (!eol)
> return 0;
OK.
> - dateptr = buf;
> - while (buf < tail && *buf++ != '\n')
> + for (dateptr = eol; dateptr > buf && dateptr[-1] != '>'; dateptr--)
> /* nada */;
OK. Just a style thing, but I found that "; /* nada */" is easier
to spot that there is an empty statement there.
> - if (buf >= tail)
> + if (dateptr == buf || dateptr == eol)
> return 0;
Curious when dateptr that wanted to scan back from eol is still at
eol after the loop. It is when the ident line ends with ">" without
any timestamp/tz info. And the reason why we need to check that
here is ...
> - /* dateptr < buf && buf[-1] == '\n', so parsing will stop at buf-1 */
> +
> + /* dateptr < eol && *eol == '\n', so parsing will stop at eol */
> return parse_timestamp(dateptr, NULL, 10);
... because parse_timestamp() is merely strtoumax() and would
happily skip over arbitrary number of leading "whitespace" without
stopping if (dateptr == eol && *eol == '\n'). OK, sad but correct.
next prev parent reply other threads:[~2023-04-24 17:05 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-14 11:37 Weird behavior of 'git log --before' or 'git log --date-order': Commits from 2011 are treated to be before 1980 Thomas Bock
2023-04-15 8:52 ` Jeff King
2023-04-15 8:59 ` Jeff King
2023-04-15 14:10 ` Kristoffer Haugsbakk
2023-04-17 5:40 ` Jeff King
2023-04-17 6:20 ` Kristoffer Haugsbakk
2023-04-17 7:41 ` Jeff King
2023-04-27 22:32 ` Kristoffer Haugsbakk
2023-04-17 9:51 ` Junio C Hamano
2023-04-18 4:12 ` Jeff King
2023-04-18 14:02 ` Derrick Stolee
2023-04-21 14:51 ` Thomas Bock
2023-04-22 13:41 ` [PATCH 0/3] fixing some parse_commit() timestamp corner cases Jeff King
2023-04-22 13:42 ` [PATCH 1/3] t4212: avoid putting git on left-hand side of pipe Jeff King
2023-04-22 13:47 ` [PATCH 2/3] parse_commit(): parse timestamp from end of line Jeff King
2023-04-24 17:05 ` Junio C Hamano [this message]
2023-04-25 5:23 ` Jeff King
2023-04-24 16:39 ` [PATCH 0/3] fixing some parse_commit() timestamp corner cases Junio C Hamano
2023-04-25 5:52 ` [PATCH v2 " Jeff King
2023-04-25 5:54 ` Jeff King
2023-04-25 5:54 ` [PATCH v2 1/4] t4212: avoid putting git on left-hand side of pipe Jeff King
2023-04-25 5:54 ` [PATCH v2 2/4] parse_commit(): parse timestamp from end of line Jeff King
2023-04-25 5:54 ` [PATCH v2 3/4] parse_commit(): handle broken whitespace-only timestamp Jeff King
2023-04-25 10:11 ` Phillip Wood
2023-04-25 16:06 ` Junio C Hamano
2023-04-26 11:36 ` Jeff King
2023-04-26 15:32 ` Junio C Hamano
2023-04-27 8:13 ` [PATCH v3 0/4] fixing some parse_commit() timestamp corner cases Jeff King
2023-04-27 8:14 ` [PATCH v3 1/4] t4212: avoid putting git on left-hand side of pipe Jeff King
2023-04-27 8:14 ` [PATCH v3 2/4] parse_commit(): parse timestamp from end of line Jeff King
2023-04-27 8:17 ` [PATCH v3 3/4] parse_commit(): handle broken whitespace-only timestamp Jeff King
2023-04-27 10:11 ` Phillip Wood
2023-04-27 11:55 ` Phillip Wood
2023-04-27 16:46 ` Jeff King
2023-04-27 16:20 ` Junio C Hamano
2023-04-27 16:55 ` Jeff King
2023-04-27 16:25 ` Junio C Hamano
2023-04-27 16:57 ` Jeff King
2023-04-27 8:17 ` [PATCH v3 4/4] parse_commit(): describe more date-parsing failure modes Jeff King
2023-04-27 8:18 ` [PATCH v3 0/4] fixing some parse_commit() timestamp corner cases Jeff King
2023-04-27 16:32 ` Junio C Hamano
2023-04-26 14:06 ` [PATCH v2 3/4] parse_commit(): handle broken whitespace-only timestamp Phillip Wood
2023-04-26 14:31 ` Andreas Schwab
2023-04-26 14:44 ` Phillip Wood
2023-04-25 5:55 ` [PATCH v2 4/4] parse_commit(): describe more date-parsing failure modes Jeff King
2023-04-22 13:52 ` Weird behavior of 'git log --before' or 'git log --date-order': Commits from 2011 are treated to be before 1980 Jeff King
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