Subject: [GSoC][PATCH v5 07/12] refs: set up ref consistency check infrastructure

From: shejialuo <[email-masked]>
Date: Thu, 27 Jun 2024 23:15:14 +0800

The interfaces defined in the `ref_storage_be` are carefully structured
in semantic. It's organized as the five parts:

1. The name and the initialization interfaces.
2. The ref transaction interfaces.
3. The ref internal interfaces (pack, rename and copy).
4. The ref filesystem interfaces.
5. The reflog related interfaces.

To keep consistent with the git-fsck(1), add a new interface named
"fsck_refs_fn" to the end of "ref_storage_be". This semantic cannot be
grouped into any above five categories. Explicitly add blank line to
make it different from others.

Mentored-by: Patrick Steinhardt <[email-masked]>
Mentored-by: Karthik Nayak <[email-masked]>
Signed-off-by: shejialuo <[email-masked]>
---
 refs.c                  |  5 +++++
 refs.h                  |  8 ++++++++
 refs/debug.c            | 11 +++++++++++
 refs/files-backend.c    | 15 ++++++++++++++-
 refs/packed-backend.c   |  8 ++++++++
 refs/refs-internal.h    |  6 ++++++
 refs/reftable-backend.c |  8 ++++++++
 7 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/refs.c b/refs.c
index dd0d9c360f..646fdfaf22 100644
--- a/refs.c
+++ b/refs.c
@@ -316,6 +316,11 @@ int check_refname_format(const char *refname, int flags)
 	return check_or_sanitize_refname(refname, flags, NULL);
 }
 
+int refs_fsck(struct ref_store *refs, struct fsck_refs_options *o)
+{
+	return refs->be->fsck(refs, o);
+}
+
 void sanitize_refname_component(const char *refname, struct strbuf *out)
 {
 	if (check_or_sanitize_refname(refname, REFNAME_ALLOW_ONELEVEL, out))
diff --git a/refs.h b/refs.h
index df8cbf6124..a8f4deb108 100644
--- a/refs.h
+++ b/refs.h
@@ -3,6 +3,7 @@
 
 #include "commit.h"
 
+struct fsck_refs_options;
 struct object_id;
 struct ref_store;
 struct repository;
@@ -547,6 +548,13 @@ int refs_for_each_reflog(struct ref_store *refs, each_reflog_fn fn, void *cb_dat
  */
 int check_refname_format(const char *refname, int flags);
 
+/*
+ * Check the reference database for consistency. Return 0 if refs and
+ * reflogs are consistent, and non-zero otherwise. The errors will be
+ * written to stderr.
+ */
+int refs_fsck(struct ref_store *refs, struct fsck_refs_options *o);
+
 /*
  * Apply the rules from check_refname_format, but mutate the result until it
  * is acceptable, and place the result in "out".
diff --git a/refs/debug.c b/refs/debug.c
index 547d9245b9..6306c25fd3 100644
--- a/refs/debug.c
+++ b/refs/debug.c
@@ -419,6 +419,15 @@ static int debug_reflog_expire(struct ref_store *ref_store, const char *refname,
 	return res;
 }
 
+static int debug_fsck(struct ref_store *ref_store,
+		      struct fsck_refs_options *o)
+{
+	struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+	int res = drefs->refs->be->fsck(drefs->refs, o);
+	trace_printf_key(&trace_refs, "fsck: %d\n", res);
+	return res;
+}
+
 struct ref_storage_be refs_be_debug = {
 	.name = "debug",
 	.init = NULL,
@@ -451,4 +460,6 @@ struct ref_storage_be refs_be_debug = {
 	.create_reflog = debug_create_reflog,
 	.delete_reflog = debug_delete_reflog,
 	.reflog_expire = debug_reflog_expire,
+
+	.fsck = debug_fsck,
 };
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 44c5c3b201..7257fffb77 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -3406,6 +3406,17 @@ static int files_ref_store_remove_on_disk(struct ref_store *ref_store,
 	return ret;
 }
 
+static int files_fsck(struct ref_store *ref_store,
+		      struct fsck_refs_options *o)
+{
+	int ret;
+	struct files_ref_store *refs =
+		files_downcast(ref_store, REF_STORE_READ, "fsck");
+
+	ret = refs->packed_ref_store->be->fsck(refs->packed_ref_store, o);
+	return ret;
+}
+
 struct ref_storage_be refs_be_files = {
 	.name = "files",
 	.init = files_ref_store_init,
@@ -3432,5 +3443,7 @@ struct ref_storage_be refs_be_files = {
 	.reflog_exists = files_reflog_exists,
 	.create_reflog = files_create_reflog,
 	.delete_reflog = files_delete_reflog,
-	.reflog_expire = files_reflog_expire
+	.reflog_expire = files_reflog_expire,
+
+	.fsck = files_fsck,
 };
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index c4c1e36aa2..db152053f8 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -1733,6 +1733,12 @@ static struct ref_iterator *packed_reflog_iterator_begin(struct ref_store *ref_s
 	return empty_ref_iterator_begin();
 }
 
+static int packed_fsck(struct ref_store *ref_store,
+		       struct fsck_refs_options *o)
+{
+	return 0;
+}
+
 struct ref_storage_be refs_be_packed = {
 	.name = "packed",
 	.init = packed_ref_store_init,
@@ -1760,4 +1766,6 @@ struct ref_storage_be refs_be_packed = {
 	.create_reflog = NULL,
 	.delete_reflog = NULL,
 	.reflog_expire = NULL,
+
+	.fsck = packed_fsck,
 };
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index fa975d69aa..ecc082baf8 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -4,6 +4,7 @@
 #include "refs.h"
 #include "iterator.h"
 
+struct fsck_options;
 struct ref_transaction;
 
 /*
@@ -650,6 +651,9 @@ typedef int read_raw_ref_fn(struct ref_store *ref_store, const char *refname,
 typedef int read_symbolic_ref_fn(struct ref_store *ref_store, const char *refname,
 				 struct strbuf *referent);
 
+typedef int fsck_fn(struct ref_store *ref_store,
+		    struct fsck_refs_options *o);
+
 struct ref_storage_be {
 	const char *name;
 	ref_store_init_fn *init;
@@ -677,6 +681,8 @@ struct ref_storage_be {
 	create_reflog_fn *create_reflog;
 	delete_reflog_fn *delete_reflog;
 	reflog_expire_fn *reflog_expire;
+
+	fsck_fn *fsck;
 };
 
 extern struct ref_storage_be refs_be_files;
diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
index 7d872a32ac..2a358b40ca 100644
--- a/refs/reftable-backend.c
+++ b/refs/reftable-backend.c
@@ -2292,6 +2292,12 @@ static int reftable_be_reflog_expire(struct ref_store *ref_store,
 	return ret;
 }
 
+static int reftable_be_fsck(struct ref_store *ref_store,
+			    struct fsck_refs_options *o)
+{
+	return 0;
+}
+
 struct ref_storage_be refs_be_reftable = {
 	.name = "reftable",
 	.init = reftable_be_init,
@@ -2319,4 +2325,6 @@ struct ref_storage_be refs_be_reftable = {
 	.create_reflog = reftable_be_create_reflog,
 	.delete_reflog = reftable_be_delete_reflog,
 	.reflog_expire = reftable_be_reflog_expire,
+
+	.fsck = reftable_be_fsck,
 };
-- 
2.45.2