From: "brian m. carlson" <sandals@crustytoothpaste.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH v2 1/2] builtin/checkout: simplify metadata initialization
Date: Sat, 23 May 2020 12:22:05 +0000 [thread overview]
Message-ID: <20200523122205.GA1915090@camp.crustytoothpaste.net> (raw)
In-Reply-To: <xmqq1rndtcmd.fsf@gitster.c.googlers.com>
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On 2020-05-21 at 17:35:22, Junio C Hamano wrote:
> "brian m. carlson" <sandals@crustytoothpaste.net> writes:
>
> > ... The only case in which we do not have a commit object is when
> > invoking git switch with --orphan. Moreover, we can only hit this code
> > path without a commit object additionally with either --force or
> > --discard-changes.
>
> It was easy for me to trace the codepath to see when these options
> are used we end up with no commit object, but I ran out of time
> trying to see if the "forced orphan" is the only way to end up with
> a NULL in new_branch_info->commit. Assuming that is true, of course
> the following perfectly makes sense.
I believe it is. The only case in which we have a NULL commit as far as
I can tell is with switch and an orphan, and in merge_working_tree we
call reset_tree either if the changes are discarded or unpack_trees
couldn't do a trivial merge. Since I'm pretty sure unpack_trees can
indeed merge with the empty tree, we would only call reset_trees with
--discard-changes or --force. And reset_tree is only called from
merge_working_tree.
In addition, I did try other situations plus the entire testsuite with
my erroneous first patch and was unable to cause a segfault anywhere
(which would have been a trivial NULL dereference) in case I missed
something, which leads me to believe that this is in fact the only
situation in which this occurs.
--
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204
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next prev parent reply other threads:[~2020-05-23 12:22 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-15 17:22 Git Test Coverage Report (v2.27.0-rc0) Derrick Stolee
2020-05-19 12:11 ` Derrick Stolee
2020-05-19 20:07 ` René Scharfe
2020-05-19 23:42 ` brian m. carlson
2020-05-20 1:38 ` brian m. carlson
2020-05-19 18:31 ` [PATCH] t4067: make rename detection test output raw diff Jonathan Tan
2020-05-19 19:00 ` Derrick Stolee
2020-05-20 1:41 ` [PATCH 1/1] builtin/checkout: simplify metadata initialization brian m. carlson
2020-05-20 15:17 ` Junio C Hamano
2020-05-20 22:37 ` brian m. carlson
2020-05-21 2:07 ` [PATCH v2 0/2] Improve Fix code coverage for checkout brian m. carlson
2020-05-21 2:07 ` [PATCH v2 1/2] builtin/checkout: simplify metadata initialization brian m. carlson
2020-05-21 17:35 ` Junio C Hamano
2020-05-23 12:22 ` brian m. carlson [this message]
2020-05-21 2:07 ` [PATCH v2 2/2] t2060: add a test for switch with --orphan and --discard-changes brian m. carlson
2020-05-21 12:38 ` [PATCH v2 0/2] Improve Fix code coverage for checkout Derrick Stolee
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