Re: [PATCH v6 28/32] config: read ref storage config on startup

[Jeff King <peff@peff.net>]

On Mon, Feb 29, 2016 at 05:10:24PM -0500, Jeff King wrote:

> > We apparently don't always call check_repo_format before calling
> > git_config_early -- or, more to the point, before doing ref operations.
> > So I think we need this in git_config_early.
> 
> That seems horribly broken, though. If a program is accessing refs
> without calling check_repository_format, isn't it bypassing all of our
> regular version and extension checks?
> 
> I think we should be smoking out such cases (e.g., by setting
> a null refs-backend, as I mentioned earlier) and fixing them, rather
> than working around them by putting the backend setup in the wrong
> place.

So even without your series, this isn't too bad to instrument, like the
patch below.

It does reveal a handful of failures in the test suite. I haven't dug
yet, but I strongly suspect those are all bugs that should be fixed.

diff --git a/cache.h b/cache.h
index af2aeb8..a286f99 100644
--- a/cache.h
+++ b/cache.h
@@ -639,6 +639,7 @@ extern int hold_locked_index(struct lock_file *, int);
 extern void set_alternate_index_output(const char *);
 
 /* Environment bits from configuration mechanism */
+extern int repo_initialized;
 extern int trust_executable_bit;
 extern int trust_ctime;
 extern int check_stat;
diff --git a/environment.c b/environment.c
index 10451ee..6ee9812 100644
--- a/environment.c
+++ b/environment.c
@@ -12,6 +12,7 @@
 #include "fmt-merge-msg.h"
 #include "commit.h"
 
+int repo_initialized;
 int trust_executable_bit = 1;
 int trust_ctime = 1;
 int check_stat = 1;
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 339f5c7..a4e9df6 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -947,6 +947,9 @@ static struct ref_cache *lookup_ref_cache(const char *submodule)
 {
 	struct ref_cache *refs;
 
+	if (!repo_initialized)
+		die("BUG: lookup_ref_cache called without initializing repo");
+
 	if (!submodule || !*submodule)
 		return &ref_cache;
 
@@ -1414,6 +1417,9 @@ static const char *resolve_ref_1(const char *refname,
 	int depth = MAXDEPTH;
 	int bad_name = 0;
 
+	if (!repo_initialized)
+		die("BUG: resolve_ref called without initializing repo");
+
 	if (flags)
 		*flags = 0;
 
diff --git a/setup.c b/setup.c
index 76609fa..ed86094 100644
--- a/setup.c
+++ b/setup.c
@@ -446,6 +446,9 @@ static int check_repository_format_gently(const char *gitdir, int *nongit_ok)
 		ret = -1;
 	}
 
+	if (ret == 0)
+		repo_initialized = 1;
+
 	strbuf_release(&sb);
 	return ret;
 }