From: Johannes Schindelin <Johannes.Schindelin@gmx.de> To: Jeff King <firstname.lastname@example.org> Cc: Johannes Schindelin via GitGitGadget <email@example.com>, firstname.lastname@example.org, Junio C Hamano <email@example.com> Subject: Re: [PATCH v2 1/1] config: work around bug with includeif:onbranch and early config Date: Thu, 1 Aug 2019 00:13:19 +0200 (CEST) [thread overview] Message-ID: <nycvar.QRO.firstname.lastname@example.org> (raw) In-Reply-To: <20190731220204.GA1933@sigill.intra.peff.net> Hi Peff, On Wed, 31 Jul 2019, Jeff King wrote: > On Wed, Jul 31, 2019 at 01:06:42PM -0700, Johannes Schindelin via GitGitGadget wrote: > > > Technically, there is a way to solve this properly: teach the refs > > machinery to initialize the ref_store from a given gitdir/commondir pair > > (which we _do_ have in the early config code path), and then use that in > > `include_by_branch()`. This, however, is a pretty involved project, and > > we're already in the feature freeze for Git v2.23.0. > > This gets tricky, because some commands are intentionally avoiding the > normal lookup procedure (e.g., clone or init, and probably things like > upload-pack that want to enter another repo). So I think it is OK as > long as the early-config code is explicitly saying "and please look at > the refs in this specific direectory now", and it doesn't affect other > possible code paths that might look at refs. I _think_ that's what > you're suggesting above, but I just want to make sure (not that it > matters either way for this patch). I think we already have the `git clone` problem with `includeif.gitdir:`. AFAICT we _will_ discover a Git directory when cloning inside an existing Git worktree. > As a workaround, I suspect in many cases it might work to simply do a > gentle setup (e.g., in "help"), but we simply weren't doing it before > because there was no use case. That obviously wouldn't work for > something like clone, though. Right. And as you say, there was no use case, and I would even contend that there still is no use case. In the cover letter, I tried to concoct something (using a branch-dependent pager) that sounds _really_ far-fetched to even me. > > > diff --git a/config.c b/config.c > > index ed7f58e0fc..3900e4947b 100644 > > --- a/config.c > > +++ b/config.c > > @@ -275,7 +275,8 @@ static int include_by_branch(const char *cond, size_t cond_len) > > int flags; > > int ret; > > struct strbuf pattern = STRBUF_INIT; > > - const char *refname = resolve_ref_unsafe("HEAD", 0, NULL, &flags); > > + const char *refname = !the_repository || !the_repository->gitdir ? > > + NULL : resolve_ref_unsafe("HEAD", 0, NULL, &flags); > > I think the_repository is always non-NULL. No, it totally can be `NULL`. I know because my first version of the patch did not have that extra check, and `git help -a` would segfault outside a Git worktree when I had an `includeif.onbranch:` in my `~/.gitconfig`. I tried to explain that in the commit message, but obviously did a poor job: Note: when calling above-mentioned two commands _outside_ of any Git worktree (passing the `--global` flag to `git config`, as there is obviously no repository config available), at the point when `include_by_branch()` is called, `the_repository` is `NULL`, therefore we have to be extra careful not to dereference it in that case. > The way similar sites check this is withV > "!startup_info->have_repository" or have_git_dir(). The early-config > code uses the latter, so we should probably match it here. Quite frankly, I'd rather not. At this point, it is not important whether or not we discovered a Git directory, but whether or not we have populated a dereference'able `the_repository`. Those are two different things. > Side note: I suspect there are some cleanup opportunities. IIRC, I had > to add have_git_dir() to cover some cases where $GIT_DIR was set but > we hadn't explicitly done a setup step, but there's been a lot of > refactoring and cleanup in the initialization code since then. I'm not > sure if it's still necessary. Yeah, well, I am not necessarily certain that we always ask the right questions, such as asking whether we found a startup repository when we need, in fact, to know whether `the_repository->refs` would cause a segmentation fault because we would dereference a `NULL` pointer ;-) > > > diff --git a/t/t1309-early-config.sh b/t/t1309-early-config.sh > > index 413642aa56..0c37e7180d 100755 > > --- a/t/t1309-early-config.sh > > +++ b/t/t1309-early-config.sh > > @@ -89,4 +89,9 @@ test_expect_failure 'ignore .git/ with invalid config' ' > > test_with_config "[" > > ' > > > > +test_expect_success 'early config and onbranch' ' > > + echo "[broken" >broken && > > + test_with_config "[includeif \"onbranch:refs/heads/master\"]path=../broken" > > +' > > OK, so we know we didn't see the broken config because we'd have barfed > if we actually included it. Makes sense. That was the idea :-) Thanks for the review! Dscho
next prev parent reply other threads:[~2019-07-31 22:13 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-31 19:53 [PATCH 0/1] Make the includeif:onbranch feature more robust Johannes Schindelin via GitGitGadget 2019-07-31 19:53 ` [PATCH 1/1] config: work around bug with includeif:onbranch and early config Johannes Schindelin via GitGitGadget 2019-07-31 21:37 ` Junio C Hamano 2019-07-31 20:06 ` [PATCH v2 0/1] Make the includeif:onbranch feature more robust Johannes Schindelin via GitGitGadget 2019-07-31 20:06 ` [PATCH v2 1/1] config: work around bug with includeif:onbranch and early config Johannes Schindelin via GitGitGadget 2019-07-31 22:02 ` Jeff King 2019-07-31 22:13 ` Johannes Schindelin [this message] 2019-07-31 23:12 ` Jeff King 2019-08-01 0:49 ` Jeff King 2019-08-01 17:24 ` Jeff Hostetler 2019-08-06 12:26 ` [PATCH 0/3] the_repository initialization cleanup Jeff King 2019-08-06 12:26 ` [PATCH 1/3] t1309: use short branch name in includeIf.onbranch test Jeff King 2019-08-06 12:27 ` [PATCH 2/3] common-main: delay trace2 initialization Jeff King 2019-08-06 12:27 ` [PATCH 3/3] config: stop checking whether the_repository is NULL Jeff King 2019-08-06 12:49 ` Jeff King 2019-08-08 19:48 ` Johannes Schindelin 2019-08-06 12:56 ` [PATCH v2 1/1] config: work around bug with includeif:onbranch and early config Jeff King
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