Re: [PATCH] bisect: fix replay of CRLF logs

From: Junio C Hamano <gitster@pobox.com>
Date: May 8, 2020, 15:07 UTC
Message-ID: <xmqqh7wq1n52.fsf@gitster.c.googlers.com>
In-Reply-To: <20200508130831.GB631018@coredump.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 11 quoted lines

> On Thu, May 07, 2020 at 04:07:54PM -0700, Junio C Hamano wrote:
>
>> Jeff King <peff@peff.net> writes:
>> 
>> > The simplest fix is probably to clean up "$file" into another tempfile,
>> > and then read from that.
>> 
>> Or just tell the users do not break the log file (or they can keep
>> both halves)?
>
> I am OK with that, too. :)

Well, that was tongue-in-cheek.

The log is designed to be edited and then run via the shell or fed to the "bisect replay" subcommand, so if a (wide) class of editors tend to "corrupt" the edited result in a known and recoverable way, we should deal with it.

Replaying is just setting the refs the logged session should have known about (without checking out the revisions at each step) and doing the final checkout, so it should be a fast operation, and penalizing majority of users by paying the cost to dos2unix copy the file "just in case" feels somewhat ugly. I wish we were dumb and checked out each and every intermediate steps---then the cost for such a "just in case" clean-up would have been dwarfed in the noise.

I wonder if we can add a CR to IFS so that the parsing logic of each line would not even see it?

 bisect_replay () {
         file="$1"
         test "$#" -eq 1 || die "$(gettext "No logfile given")"
         test -r "$file" || die "$(eval_gettext "cannot read \$file for replaying")"
         git bisect--helper --bisect-reset || exit
+        IFS="$IFS$(printf "\015")"
         while read git bisect command rev
         do
                 test "$git $bisect" = "git bisect" ||
                 test "$git" = "git-bisect" || continue