config: work around bug with includeif:onbranch and early config

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/config.c b/config.c
index ed7f58e0fcf221733165f3dd6a9d095d727a0a5e..3900e4947be92b916ed9b531eb455e8f856105dc 100644 (file)
--- 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 413642aa5672800d1b7be448bc97d175add07ee4..0c37e7180d1cde57d49c12deb28239c509d9207d 100755 (executable)
--- 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