Teach git-repack to preserve objects referred to by reflog entries.

This adds a new option --reflog to pack-objects and revision
machinery; do not bother documenting it for now, since this is
only useful for local repacking.

When the option is passed, objects reachable from reflog entries
are marked as interesting while computing the set of objects to
pack.

Signed-off-by: Junio C Hamano <junkio@cox.net>

3 files changed, 52 insertions, 9 deletions

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index 807be8c3f..9e15beb3b 100644
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -17,7 +17,7 @@ static const char pack_usage[] = "\
 git-pack-objects [{ -q | --progress | --all-progress }] \n\
 	[--local] [--incremental] [--window=N] [--depth=N] \n\
 	[--no-reuse-delta] [--delta-base-offset] [--non-empty] \n\
-	[--revs [--unpacked | --all]*] [--stdout | base-name] \n\
+	[--revs [--unpacked | --all]*] [--reflog] [--stdout | base-name] \n\
 	[<ref-list | <object-list]";
 
 struct object_entry {
@@ -1575,6 +1575,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 		}
 		if (!strcmp("--unpacked", arg) ||
 		    !strncmp("--unpacked=", arg, 11) ||
+		    !strcmp("--reflog", arg) ||
 		    !strcmp("--all", arg)) {
 			use_internal_rev_list = 1;
 			if (ARRAY_SIZE(rp_av) - 1 <= rp_ac)
diff --git a/git-repack.sh b/git-repack.sh
index 067898f12..375434b1d 100755
--- a/git-repack.sh
+++ b/git-repack.sh
@@ -62,7 +62,7 @@ case ",$all_into_one," in
 esac
 
 args="$args $local $quiet $no_reuse_delta$extra"
-name=$(git-pack-objects --non-empty --all $args </dev/null "$PACKTMP") ||
+name=$(git-pack-objects --non-empty --all --reflog $args </dev/null "$PACKTMP") ||
 	exit 1
 if [ -z "$name" ]; then
 	echo Nothing new to pack.
diff --git a/revision.c b/revision.c
index 4dae5342e..bda9d4dfa 100644
--- a/revision.c
+++ b/revision.c
@@ -464,21 +464,59 @@ static void limit_list(struct rev_info *revs)
 	revs->commits = newlist;
 }
 
-static int all_flags;
-static struct rev_info *all_revs;
+struct all_refs_cb {
+	int all_flags;
+	struct rev_info *all_revs;
+	const char *name_for_errormsg;
+};
 
 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 {
-	struct object *object = get_reference(all_revs, path, sha1, all_flags);
-	add_pending_object(all_revs, object, "");
+	struct all_refs_cb *cb = cb_data;
+	struct object *object = get_reference(cb->all_revs, path, sha1,
+					      cb->all_flags);
+	add_pending_object(cb->all_revs, object, "");
 	return 0;
 }
 
 static void handle_all(struct rev_info *revs, unsigned flags)
 {
-	all_revs = revs;
-	all_flags = flags;
-	for_each_ref(handle_one_ref, NULL);
+	struct all_refs_cb cb;
+	cb.all_revs = revs;
+	cb.all_flags = flags;
+	for_each_ref(handle_one_ref, &cb);
+}
+
+static int handle_one_reflog_ent(unsigned char *osha1, unsigned char *nsha1, char *detail, void *cb_data)
+{
+	struct all_refs_cb *cb = cb_data;
+	struct object *object;
+
+	if (!is_null_sha1(osha1)) {
+		object = get_reference(cb->all_revs, cb->name_for_errormsg,
+				       osha1, cb->all_flags);
+		add_pending_object(cb->all_revs, object, "");
+	}
+	object = get_reference(cb->all_revs, cb->name_for_errormsg,
+			       nsha1, cb->all_flags);
+	add_pending_object(cb->all_revs, object, "");
+	return 0;
+}
+
+static int handle_one_reflog(const char *path, const unsigned char *sha1, int flag, void *cb_data)
+{
+	struct all_refs_cb *cb = cb_data;
+	cb->name_for_errormsg = path;
+	for_each_reflog_ent(path, handle_one_reflog_ent, cb_data);
+	return 0;
+}
+
+static void handle_reflog(struct rev_info *revs, unsigned flags)
+{
+	struct all_refs_cb cb;
+	cb.all_revs = revs;
+	cb.all_flags = flags;
+	for_each_ref(handle_one_reflog, &cb);
 }
 
 static int add_parents_only(struct rev_info *revs, const char *arg, int flags)
@@ -805,6 +843,10 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 				handle_all(revs, flags);
 				continue;
 			}
+			if (!strcmp(arg, "--reflog")) {
+				handle_reflog(revs, flags);
+				continue;
+			}
 			if (!strcmp(arg, "--not")) {
 				flags ^= UNINTERESTING;
 				continue;