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From: "Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Junio C Hamano <gitster@pobox.com>,
	Johannes Schindelin <johasc@microsoft.com>
Subject: [PATCH 1/1] config: work around bug with includeif:onbranch and early config
Date: Wed, 31 Jul 2019 12:53:51 -0700 (PDT)	[thread overview]
Message-ID: <4aa88340132b03c9480c781cb5cb3c5b5513e944.1564602830.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.300.git.gitgitgadget@gmail.com>

From: Johannes Schindelin <johasc@microsoft.com>

Since 07b2c0eacac (config: learn the "onbranch:" includeIf condition,
2019-06-05), there is a potential catch-22 in the early config path: if
the `include.onbranch:` feature is used, Git assumes that the Git
directory has been initialized already. However, in the early config
code path that is not true.

One way to trigger this is to call the following commands in any
repository:

	git config includeif.onbranch:refs/heads/master.path broken
	git help -a

The symptom triggered by the `git help -a` invocation reads like this:

BUG: refs.c:1851: attempting to get main_ref_store outside of repository

Let's work around this, simply by ignoring the `includeif.onbranch:`
setting when parsing the config when the ref store has not been
initialized (yet).

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.

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.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 config.c                | 3 ++-
 t/t1309-early-config.sh | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

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);
 	const char *shortname;
 
 	if (!refname || !(flags & REF_ISSYMREF)	||
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"
+'
+
 test_done
-- 
gitgitgadget

  reply	other threads:[~2019-07-31 19:53 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 ` Johannes Schindelin via GitGitGadget [this message]
2019-07-31 21:37   ` [PATCH 1/1] config: work around bug with includeif:onbranch and early config 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
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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