Subject: [PATCH v3 1/2] update_symref: add REF_CREATE_ONLY option

From: Bence Ferdinandy <[email-masked]>
Date: Thu, 19 Sep 2024 14:13:25 +0200

Add a new REF_CREATE_ONLY flag for use by the files backend which will
only update the symref if it doesn't already exist. Add the possibility
to pass extra flags to refs_update_symref so that it can utilize this
new flag.

Signed-off-by: Bence Ferdinandy <[email-masked]>
---

Notes:
    v3: new patch, passes all tests on it's own

 builtin/branch.c          |  2 +-
 builtin/checkout.c        |  4 ++--
 builtin/clone.c           |  6 +++---
 builtin/notes.c           |  2 +-
 builtin/remote.c          |  6 +++---
 builtin/symbolic-ref.c    |  2 +-
 builtin/worktree.c        |  2 +-
 refs.c                    |  6 +++---
 refs.h                    | 12 ++++++++++--
 refs/files-backend.c      |  8 ++++++++
 reset.c                   |  2 +-
 sequencer.c               |  2 +-
 setup.c                   |  2 +-
 t/helper/test-ref-store.c |  2 +-
 14 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/builtin/branch.c b/builtin/branch.c
index c98601c6fe..6025bca45e 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -559,7 +559,7 @@ static int replace_each_worktree_head_symref(struct worktree **worktrees,
 			continue;
 
 		refs = get_worktree_ref_store(worktrees[i]);
-		if (refs_update_symref(refs, "HEAD", newref, logmsg))
+		if (refs_update_symref(refs, "HEAD", newref, 0, logmsg))
 			ret = error(_("HEAD of working tree %s is not updated"),
 				    worktrees[i]->path);
 	}
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 4cfe6fab50..23e28321d6 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1011,7 +1011,7 @@ static void update_refs_for_switch(const struct checkout_opts *opts,
 			describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 		}
 	} else if (new_branch_info->path) {	/* Switch branches. */
-		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", new_branch_info->path, msg.buf) < 0)
+		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", new_branch_info->path, 0, msg.buf) < 0)
 			die(_("unable to update HEAD"));
 		if (!opts->quiet) {
 			if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
@@ -1475,7 +1475,7 @@ static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
 		die(_("You are on a branch yet to be born"));
 	strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
 	status = refs_update_symref(get_main_ref_store(the_repository),
-				    "HEAD", branch_ref.buf, "checkout -b");
+				    "HEAD", branch_ref.buf, 0, "checkout -b");
 	strbuf_release(&branch_ref);
 	if (!opts->quiet)
 		fprintf(stderr, _("Switched to a new branch '%s'\n"),
diff --git a/builtin/clone.c b/builtin/clone.c
index 269b6e18a4..43b7878a79 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -659,7 +659,7 @@ static void update_remote_refs(const struct ref *refs,
 		strbuf_addstr(&head_ref, branch_top);
 		strbuf_addstr(&head_ref, "HEAD");
 		if (refs_update_symref(get_main_ref_store(the_repository), head_ref.buf,
-				       remote_head_points_at->peer_ref->name,
+				       remote_head_points_at->peer_ref->name, 0,
 				       msg) < 0)
 			die(_("unable to update %s"), head_ref.buf);
 		strbuf_release(&head_ref);
@@ -672,7 +672,7 @@ static void update_head(const struct ref *our, const struct ref *remote,
 	const char *head;
 	if (our && skip_prefix(our->name, "refs/heads/", &head)) {
 		/* Local default branch link */
-		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", our->name, NULL) < 0)
+		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", our->name, 0, NULL) < 0)
 			die(_("unable to update HEAD"));
 		if (!option_bare) {
 			refs_update_ref(get_main_ref_store(the_repository),
@@ -701,7 +701,7 @@ static void update_head(const struct ref *our, const struct ref *remote,
 		 * Unborn head from remote; same as "our" case above except
 		 * that we have no ref to update.
 		 */
-		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", unborn, NULL) < 0)
+		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", unborn, 0, NULL) < 0)
 			die(_("unable to update HEAD"));
 		if (!option_bare)
 			install_branch_config(0, head, remote_name, unborn);
diff --git a/builtin/notes.c b/builtin/notes.c
index 04f9dfb7fb..6b42d1139f 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -978,7 +978,7 @@ static int merge(int argc, const char **argv, const char *prefix)
 			die(_("a notes merge into %s is already in-progress at %s"),
 			    default_notes_ref(), wt->path);
 		free_worktrees(worktrees);
-		if (refs_update_symref(get_main_ref_store(the_repository), "NOTES_MERGE_REF", default_notes_ref(), NULL))
+		if (refs_update_symref(get_main_ref_store(the_repository), "NOTES_MERGE_REF", default_notes_ref(), 0, NULL))
 			die(_("failed to store link to current notes ref (%s)"),
 			    default_notes_ref());
 		fprintf(stderr, _("Automatic notes merge failed. Fix conflicts in %s "
diff --git a/builtin/remote.c b/builtin/remote.c
index 0acc547d69..d28c65599d 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -243,7 +243,7 @@ static int add(int argc, const char **argv, const char *prefix)
 		strbuf_reset(&buf2);
 		strbuf_addf(&buf2, "refs/remotes/%s/%s", name, master);
 
-		if (refs_update_symref(get_main_ref_store(the_repository), buf.buf, buf2.buf, "remote add"))
+		if (refs_update_symref(get_main_ref_store(the_repository), buf.buf, buf2.buf, 0, "remote add"))
 			result = error(_("Could not setup master '%s'"), master);
 	}
 
@@ -863,7 +863,7 @@ static int mv(int argc, const char **argv, const char *prefix)
 		strbuf_reset(&buf3);
 		strbuf_addf(&buf3, "remote: renamed %s to %s",
 				item->string, buf.buf);
-		if (refs_update_symref(get_main_ref_store(the_repository), buf.buf, buf2.buf, buf3.buf))
+		if (refs_update_symref(get_main_ref_store(the_repository), buf.buf, buf2.buf, 0, buf3.buf))
 			die(_("creating '%s' failed"), buf.buf);
 		display_progress(progress, ++refs_renamed_nr);
 	}
@@ -1443,7 +1443,7 @@ static int set_head(int argc, const char **argv, const char *prefix)
 		/* make sure it's valid */
 		if (!refs_ref_exists(get_main_ref_store(the_repository), buf2.buf))
 			result |= error(_("Not a valid ref: %s"), buf2.buf);
-		else if (refs_update_symref(get_main_ref_store(the_repository), buf.buf, buf2.buf, "remote set-head"))
+		else if (refs_update_symref(get_main_ref_store(the_repository), buf.buf, buf2.buf, 0, "remote set-head"))
 			result |= error(_("Could not setup %s"), buf.buf);
 		else if (opt_a)
 			printf("%s/HEAD set to %s\n", argv[0], head_name);
diff --git a/builtin/symbolic-ref.c b/builtin/symbolic-ref.c
index 81abdd170f..52de3e02af 100644
--- a/builtin/symbolic-ref.c
+++ b/builtin/symbolic-ref.c
@@ -84,7 +84,7 @@ int cmd_symbolic_ref(int argc, const char **argv, const char *prefix)
 		if (check_refname_format(argv[1], REFNAME_ALLOW_ONELEVEL) < 0)
 			die("Refusing to set '%s' to invalid ref '%s'", argv[0], argv[1]);
 		ret = !!refs_update_symref(get_main_ref_store(the_repository),
-					   argv[0], argv[1], msg);
+					   argv[0], argv[1], 0, msg);
 		break;
 	default:
 		usage_with_options(git_symbolic_ref_usage, options);
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 41e7f6a327..71434737e8 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -517,7 +517,7 @@ static int add_worktree(const char *path, const char *refname,
 		ret = refs_update_ref(wt_refs, NULL, "HEAD", &commit->object.oid,
 				      NULL, 0, UPDATE_REFS_MSG_ON_ERR);
 	else
-		ret = refs_update_symref(wt_refs, "HEAD", symref.buf, NULL);
+		ret = refs_update_symref(wt_refs, "HEAD", symref.buf, 0, NULL);
 	if (ret)
 		goto done;
 
diff --git a/refs.c b/refs.c
index ceb72d4bd7..7afe46cadc 100644
--- a/refs.c
+++ b/refs.c
@@ -2085,8 +2085,9 @@ int peel_iterated_oid(struct repository *r, const struct object_id *base, struct
 	return peel_object(r, base, peeled) ? -1 : 0;
 }
 
+
 int refs_update_symref(struct ref_store *refs, const char *ref,
-		       const char *target, const char *logmsg)
+		       const char *target, const unsigned int extra_flags, const char *logmsg)
 {
 	struct ref_transaction *transaction;
 	struct strbuf err = STRBUF_INIT;
@@ -2095,7 +2096,7 @@ int refs_update_symref(struct ref_store *refs, const char *ref,
 	transaction = ref_store_transaction_begin(refs, &err);
 	if (!transaction ||
 	    ref_transaction_update(transaction, ref, NULL, NULL,
-				   target, NULL, REF_NO_DEREF,
+				   target, NULL, REF_NO_DEREF | extra_flags,
 				   logmsg, &err) ||
 	    ref_transaction_commit(transaction, &err)) {
 		ret = error("%s", err.buf);
@@ -2920,4 +2921,3 @@ int ref_update_expects_existing_old_ref(struct ref_update *update)
 	return (update->flags & REF_HAVE_OLD) &&
 		(!is_null_oid(&update->old_oid) || update->old_target);
 }
-
diff --git a/refs.h b/refs.h
index f8b919a138..d907451d13 100644
--- a/refs.h
+++ b/refs.h
@@ -569,7 +569,7 @@ int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
 		    const char *newref, const char *logmsg);
 
 int refs_update_symref(struct ref_store *refs, const char *refname,
-		       const char *target, const char *logmsg);
+		       const char *target, const unsigned int extra_flags, const char *logmsg);
 
 enum action_on_err {
 	UPDATE_REFS_MSG_ON_ERR,
@@ -672,13 +672,21 @@ struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
  */
 #define REF_SKIP_CREATE_REFLOG (1 << 12)
 
+/*
+ * If the reference has already been created do not touch it.
+ */
+
+#define REF_CREATE_ONLY (1 << 13)
+
+
 /*
  * Bitmask of all of the flags that are allowed to be passed in to
  * ref_transaction_update() and friends:
  */
 #define REF_TRANSACTION_UPDATE_ALLOWED_FLAGS                                  \
 	(REF_NO_DEREF | REF_FORCE_CREATE_REFLOG | REF_SKIP_OID_VERIFICATION | \
-	 REF_SKIP_REFNAME_VERIFICATION | REF_SKIP_CREATE_REFLOG)
+	 REF_SKIP_REFNAME_VERIFICATION | REF_SKIP_CREATE_REFLOG | \
+	 REF_CREATE_ONLY)
 
 /*
  * Add a reference update to transaction. `new_oid` is the value that
diff --git a/refs/files-backend.c b/refs/files-backend.c
index c7f3f4e591..1440b69b87 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2993,6 +2993,8 @@ static int files_transaction_finish(struct ref_store *ref_store,
 		struct ref_update *update = transaction->updates[i];
 		struct ref_lock *lock = update->backend_data;
 
+		if (update->flags & REF_CREATE_ONLY && refs_ref_exists(ref_store, update->refname))
+			continue;
 		if (update->flags & REF_NEEDS_COMMIT ||
 		    update->flags & REF_LOG_ONLY) {
 			if (parse_and_write_reflog(refs, update, lock, err)) {
@@ -3031,6 +3033,8 @@ static int files_transaction_finish(struct ref_store *ref_store,
 	 */
 	for (i = 0; i < transaction->nr; i++) {
 		struct ref_update *update = transaction->updates[i];
+		if (update->flags & REF_CREATE_ONLY && refs_ref_exists(ref_store, update->refname))
+			continue;
 		if (update->flags & REF_DELETING &&
 		    !(update->flags & REF_LOG_ONLY) &&
 		    !(update->flags & REF_IS_PRUNING)) {
@@ -3061,6 +3065,8 @@ static int files_transaction_finish(struct ref_store *ref_store,
 	for (i = 0; i < transaction->nr; i++) {
 		struct ref_update *update = transaction->updates[i];
 		struct ref_lock *lock = update->backend_data;
+		if (update->flags & REF_CREATE_ONLY && refs_ref_exists(ref_store, update->refname))
+			continue;
 
 		if (update->flags & REF_DELETING &&
 		    !(update->flags & REF_LOG_ONLY)) {
@@ -3085,6 +3091,8 @@ static int files_transaction_finish(struct ref_store *ref_store,
 
 	for (i = 0; i < transaction->nr; i++) {
 		struct ref_update *update = transaction->updates[i];
+		if (update->flags & REF_CREATE_ONLY && refs_ref_exists(ref_store, update->refname))
+			continue;
 
 		if (update->flags & REF_DELETED_RMDIR) {
 			/*
diff --git a/reset.c b/reset.c
index b22b1be792..8dce5f2133 100644
--- a/reset.c
+++ b/reset.c
@@ -75,7 +75,7 @@ static int update_refs(const struct reset_head_opts *opts,
 				      UPDATE_REFS_MSG_ON_ERR);
 		if (!ret)
 			ret = refs_update_symref(get_main_ref_store(the_repository),
-						 "HEAD", switch_to_branch,
+						 "HEAD", switch_to_branch, 0,
 						 reflog_head);
 	}
 	if (!ret && run_hook)
diff --git a/sequencer.c b/sequencer.c
index 8d01cd50ac..924a78dab8 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -5107,7 +5107,7 @@ static int pick_commits(struct repository *r,
 			}
 			msg = reflog_message(opts, "finish", "returning to %s",
 				head_ref.buf);
-			if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", head_ref.buf, msg)) {
+			if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", head_ref.buf, 0, msg)) {
 				res = error(_("could not update HEAD to %s"),
 					head_ref.buf);
 				goto cleanup_head_ref;
diff --git a/setup.c b/setup.c
index 29f8673921..6a1fdef2c3 100644
--- a/setup.c
+++ b/setup.c
@@ -2169,7 +2169,7 @@ void create_reference_database(enum ref_storage_format ref_storage_format,
 			die(_("invalid initial branch name: '%s'"),
 			    initial_branch);
 
-		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", ref, NULL) < 0)
+		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", ref, 0, NULL) < 0)
 			exit(1);
 		free(ref);
 	}
diff --git a/t/helper/test-ref-store.c b/t/helper/test-ref-store.c
index 65346dee55..90af41edce 100644
--- a/t/helper/test-ref-store.c
+++ b/t/helper/test-ref-store.c
@@ -120,7 +120,7 @@ static int cmd_create_symref(struct ref_store *refs, const char **argv)
 	const char *target = notnull(*argv++, "target");
 	const char *logmsg = *argv++;
 
-	return refs_update_symref(refs, refname, target, logmsg);
+	return refs_update_symref(refs, refname, target, 0, logmsg);
 }
 
 static struct flag_definition transaction_flags[] = {
-- 
2.46.1.546.gaa0cd55cd3.dirty