[PATCH/RFC v2 1/3] refs: allow log-only updates

[David Turner <dturner@twopensource.com>]

The refs infrastructure learns about log-only ref updates, which only
update the reflog.  Later, we will use this to separate symbolic
reference resolution from ref updating.

Signed-off-by: David Turner <dturner@twopensource.com>
---
 refs/files-backend.c | 15 ++++++++++-----
 refs/refs-internal.h |  2 ++
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 176cf65..0800a57 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2821,7 +2821,7 @@ static int commit_ref_update(struct ref_lock *lock,
 			}
 		}
 	}
-	if (commit_ref(lock)) {
+	if (!(flags & REF_LOG_ONLY) && commit_ref(lock)) {
 		error("Couldn't set %s", lock->ref_name);
 		unlock_ref(lock);
 		return -1;
@@ -3175,7 +3175,8 @@ static int files_transaction_commit(struct ref_transaction *transaction,
 			goto cleanup;
 		}
 		if ((update->flags & REF_HAVE_NEW) &&
-		    !(update->flags & REF_DELETING)) {
+		    !(update->flags & REF_DELETING) &&
+		    !(update->flags & REF_LOG_ONLY)) {
 			int overwriting_symref = ((update->type & REF_ISSYMREF) &&
 						  (update->flags & REF_NODEREF));
 
@@ -3205,7 +3206,9 @@ static int files_transaction_commit(struct ref_transaction *transaction,
 				update->flags |= REF_NEEDS_COMMIT;
 			}
 		}
-		if (!(update->flags & REF_NEEDS_COMMIT)) {
+
+		if (!(update->flags & REF_LOG_ONLY) &&
+		    !(update->flags & REF_NEEDS_COMMIT)) {
 			/*
 			 * We didn't have to write anything to the lockfile.
 			 * Close it to free up the file descriptor:
@@ -3222,7 +3225,8 @@ static int files_transaction_commit(struct ref_transaction *transaction,
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
 
-		if (update->flags & REF_NEEDS_COMMIT) {
+		if (update->flags & REF_NEEDS_COMMIT ||
+		    update->flags & REF_LOG_ONLY) {
 			if (commit_ref_update(update->backend_data,
 					      update->new_sha1, update->msg,
 					      update->flags, err)) {
@@ -3242,7 +3246,8 @@ static int files_transaction_commit(struct ref_transaction *transaction,
 		struct ref_update *update = updates[i];
 		struct ref_lock *lock = update->backend_data;
 
-		if (update->flags & REF_DELETING) {
+		if (update->flags & REF_DELETING &&
+		    !(update->flags & REF_LOG_ONLY)) {
 			if (delete_ref_loose(lock, update->type, err)) {
 				ret = TRANSACTION_GENERIC_ERROR;
 				goto cleanup;
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index 21ac680..649ba63 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -42,6 +42,8 @@
  * value to ref_update::flags
  */
 
+#define REF_LOG_ONLY 0x80
+
 /* Include broken references in a do_for_each_ref*() iteration */
 #define DO_FOR_EACH_INCLUDE_BROKEN 0x01
 
-- 
2.4.2.749.g730654d-twtrsrc