Merge branch 'kn/update-ref-symref'

"git update-ref --stdin" learned to handle transactional updates of
symbolic-refs.

* kn/update-ref-symref:
  update-ref: add support for 'symref-update' command
  reftable: pick either 'oid' or 'target' for new updates
  update-ref: add support for 'symref-create' command
  update-ref: add support for 'symref-delete' command
  update-ref: add support for 'symref-verify' command
  refs: specify error for regular refs with `old_target`
  refs: create and use `ref_update_expects_existing_old_ref()`

4 files changed, 230 insertions, 16 deletions

diff --git a/builtin/clone.c b/builtin/clone.c
index 45d78614a4..b28f88eb43 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -580,7 +580,7 @@ static void write_remote_refs(const struct ref *local_refs)
 		if (!r->peer_ref)
 			continue;
 		if (ref_transaction_create(t, r->peer_ref->name, &r->old_oid,
-					   0, NULL, &err))
+					   NULL, 0, NULL, &err))
 			die("%s", err.buf);
 	}
 
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 0c061b2ed0..693f02b958 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1391,8 +1391,8 @@ static int prune_refs(struct display_state *display_state,
 	if (!dry_run) {
 		if (transaction) {
 			for (ref = stale_refs; ref; ref = ref->next) {
-				result = ref_transaction_delete(transaction, ref->name, NULL, 0,
-								"fetch: prune", &err);
+				result = ref_transaction_delete(transaction, ref->name, NULL,
+								NULL, 0, "fetch: prune", &err);
 				if (result)
 					goto cleanup;
 			}
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index c8d12ee0a7..f67f37febd 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -1576,7 +1576,8 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 		if (ref_transaction_delete(transaction,
 					   namespaced_name,
 					   old_oid,
-					   0, "push", &err)) {
+					   NULL, 0,
+					   "push", &err)) {
 			rp_error("%s", err.buf);
 			ret = "failed to delete";
 		} else {
diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 6cda1c08aa..471fa5c8d1 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -77,6 +77,65 @@ static char *parse_refname(const char **next)
 }
 
 /*
+ * Wrapper around parse_refname which skips the next delimiter.
+ */
+static char *parse_next_refname(const char **next)
+{
+	if (line_termination) {
+		/* Without -z, consume SP and use next argument */
+		if (!**next || **next == line_termination)
+			return NULL;
+		if (**next != ' ')
+			die("expected SP but got: %s", *next);
+	} else {
+		/* With -z, read the next NUL-terminated line */
+		if (**next)
+			return NULL;
+	}
+	/* Skip the delimiter */
+	(*next)++;
+
+	return parse_refname(next);
+}
+
+/*
+ * Wrapper around parse_arg which skips the next delimiter.
+ */
+static char *parse_next_arg(const char **next)
+{
+	struct strbuf arg = STRBUF_INIT;
+
+	if (line_termination) {
+		/* Without -z, consume SP and use next argument */
+		if (!**next || **next == line_termination)
+			return NULL;
+		if (**next != ' ')
+			die("expected SP but got: %s", *next);
+	} else {
+		/* With -z, read the next NUL-terminated line */
+		if (**next)
+			return NULL;
+	}
+	/* Skip the delimiter */
+	(*next)++;
+
+	if (line_termination) {
+		/* Without -z, use the next argument */
+		*next = parse_arg(*next, &arg);
+	} else {
+		/* With -z, use everything up to the next NUL */
+		strbuf_addstr(&arg, *next);
+		*next += arg.len;
+	}
+
+	if (arg.len)
+		return strbuf_detach(&arg, NULL);
+
+	strbuf_release(&arg);
+	return NULL;
+}
+
+/*
  * The value being parsed is <old-oid> (as opposed to <new-oid>; the
  * difference affects which error messages are generated):
  */
@@ -214,6 +273,61 @@ static void parse_cmd_update(struct ref_transaction *transaction,
 	strbuf_release(&err);
 }
 
+static void parse_cmd_symref_update(struct ref_transaction *transaction,
+				    const char *next, const char *end)
+{
+	char *refname, *new_target, *old_arg;
+	char *old_target = NULL;
+	struct strbuf err = STRBUF_INIT;
+	struct object_id old_oid;
+	int have_old_oid = 0;
+
+	refname = parse_refname(&next);
+	if (!refname)
+		die("symref-update: missing <ref>");
+
+	new_target = parse_next_refname(&next);
+	if (!new_target)
+		die("symref-update %s: missing <new-target>", refname);
+
+	old_arg = parse_next_arg(&next);
+	if (old_arg) {
+		old_target = parse_next_arg(&next);
+		if (!old_target)
+			die("symref-update %s: expected old value", refname);
+
+		if (!strcmp(old_arg, "oid")) {
+			if (repo_get_oid(the_repository, old_target, &old_oid))
+				die("symref-update %s: invalid oid: %s", refname, old_target);
+
+			have_old_oid = 1;
+		} else if (!strcmp(old_arg, "ref")) {
+			if (check_refname_format(old_target, REFNAME_ALLOW_ONELEVEL))
+				die("symref-update %s: invalid ref: %s", refname, old_target);
+		} else {
+			die("symref-update %s: invalid arg '%s' for old value", refname, old_arg);
+		}
+	}
+
+	if (*next != line_termination)
+		die("symref-update %s: extra input: %s", refname, next);
+
+	if (ref_transaction_update(transaction, refname, NULL,
+				   have_old_oid ? &old_oid : NULL,
+				   new_target,
+				   have_old_oid ? NULL : old_target,
+				   update_flags | create_reflog_flag,
+				   msg, &err))
+		die("%s", err.buf);
+
+	update_flags = default_flags;
+	free(refname);
+	free(old_arg);
+	free(old_target);
+	free(new_target);
+	strbuf_release(&err);
+}
+
 static void parse_cmd_create(struct ref_transaction *transaction,
 			     const char *next, const char *end)
 {
@@ -234,13 +348,42 @@ static void parse_cmd_create(struct ref_transaction *transaction,
 	if (*next != line_termination)
 		die("create %s: extra input: %s", refname, next);
 
-	if (ref_transaction_create(transaction, refname, &new_oid,
+	if (ref_transaction_create(transaction, refname, &new_oid, NULL,
+				   update_flags | create_reflog_flag,
+				   msg, &err))
+		die("%s", err.buf);
+
+	update_flags = default_flags;
+	free(refname);
+	strbuf_release(&err);
+}
+
+
+static void parse_cmd_symref_create(struct ref_transaction *transaction,
+				    const char *next, const char *end)
+{
+	struct strbuf err = STRBUF_INIT;
+	char *refname, *new_target;
+
+	refname = parse_refname(&next);
+	if (!refname)
+		die("symref-create: missing <ref>");
+
+	new_target = parse_next_refname(&next);
+	if (!new_target)
+		die("symref-create %s: missing <new-target>", refname);
+
+	if (*next != line_termination)
+		die("symref-create %s: extra input: %s", refname, next);
+
+	if (ref_transaction_create(transaction, refname, NULL, new_target,
 				   update_flags | create_reflog_flag,
 				   msg, &err))
 		die("%s", err.buf);
 
 	update_flags = default_flags;
 	free(refname);
+	free(new_target);
 	strbuf_release(&err);
 }
 
@@ -270,7 +413,7 @@ static void parse_cmd_delete(struct ref_transaction *transaction,
 
 	if (ref_transaction_delete(transaction, refname,
 				   have_old ? &old_oid : NULL,
-				   update_flags, msg, &err))
+				   NULL, update_flags, msg, &err))
 		die("%s", err.buf);
 
 	update_flags = default_flags;
@@ -278,6 +421,36 @@ static void parse_cmd_delete(struct ref_transaction *transaction,
 	strbuf_release(&err);
 }
 
+
+static void parse_cmd_symref_delete(struct ref_transaction *transaction,
+				    const char *next, const char *end)
+{
+	struct strbuf err = STRBUF_INIT;
+	char *refname, *old_target;
+
+	if (!(update_flags & REF_NO_DEREF))
+		die("symref-delete: cannot operate with deref mode");
+
+	refname = parse_refname(&next);
+	if (!refname)
+		die("symref-delete: missing <ref>");
+
+	old_target = parse_next_refname(&next);
+
+	if (*next != line_termination)
+		die("symref-delete %s: extra input: %s", refname, next);
+
+	if (ref_transaction_delete(transaction, refname, NULL,
+				   old_target, update_flags, msg, &err))
+		die("%s", err.buf);
+
+	update_flags = default_flags;
+	free(refname);
+	free(old_target);
+	strbuf_release(&err);
+}
+
+
 static void parse_cmd_verify(struct ref_transaction *transaction,
 			     const char *next, const char *end)
 {
@@ -297,11 +470,47 @@ static void parse_cmd_verify(struct ref_transaction *transaction,
 		die("verify %s: extra input: %s", refname, next);
 
 	if (ref_transaction_verify(transaction, refname, &old_oid,
-				   update_flags, &err))
+				   NULL, update_flags, &err))
+		die("%s", err.buf);
+
+	update_flags = default_flags;
+	free(refname);
+	strbuf_release(&err);
+}
+
+static void parse_cmd_symref_verify(struct ref_transaction *transaction,
+				    const char *next, const char *end)
+{
+	struct strbuf err = STRBUF_INIT;
+	struct object_id old_oid;
+	char *refname, *old_target;
+
+	if (!(update_flags & REF_NO_DEREF))
+		die("symref-verify: cannot operate with deref mode");
+
+	refname = parse_refname(&next);
+	if (!refname)
+		die("symref-verify: missing <ref>");
+
+	/*
+	 * old_ref is optional, if not provided, we need to ensure that the
+	 * ref doesn't exist.
+	 */
+	old_target = parse_next_refname(&next);
+	if (!old_target)
+		oidcpy(&old_oid, null_oid());
+
+	if (*next != line_termination)
+		die("symref-verify %s: extra input: %s", refname, next);
+
+	if (ref_transaction_verify(transaction, refname,
+				   old_target ? NULL : &old_oid,
+				   old_target, update_flags, &err))
 		die("%s", err.buf);
 
 	update_flags = default_flags;
 	free(refname);
+	free(old_target);
 	strbuf_release(&err);
 }
 
@@ -380,15 +589,19 @@ static const struct parse_cmd {
 	unsigned args;
 	enum update_refs_state state;
 } command[] = {
-	{ "update",  parse_cmd_update,  3, UPDATE_REFS_OPEN },
-	{ "create",  parse_cmd_create,  2, UPDATE_REFS_OPEN },
-	{ "delete",  parse_cmd_delete,  2, UPDATE_REFS_OPEN },
-	{ "verify",  parse_cmd_verify,  2, UPDATE_REFS_OPEN },
-	{ "option",  parse_cmd_option,  1, UPDATE_REFS_OPEN },
-	{ "start",   parse_cmd_start,   0, UPDATE_REFS_STARTED },
-	{ "prepare", parse_cmd_prepare, 0, UPDATE_REFS_PREPARED },
-	{ "abort",   parse_cmd_abort,   0, UPDATE_REFS_CLOSED },
-	{ "commit",  parse_cmd_commit,  0, UPDATE_REFS_CLOSED },
+	{ "update",        parse_cmd_update,        3, UPDATE_REFS_OPEN },
+	{ "create",        parse_cmd_create,        2, UPDATE_REFS_OPEN },
+	{ "delete",        parse_cmd_delete,        2, UPDATE_REFS_OPEN },
+	{ "verify",        parse_cmd_verify,        2, UPDATE_REFS_OPEN },
+	{ "symref-update", parse_cmd_symref_update, 4, UPDATE_REFS_OPEN },
+	{ "symref-create", parse_cmd_symref_create, 2, UPDATE_REFS_OPEN },
+	{ "symref-delete", parse_cmd_symref_delete, 2, UPDATE_REFS_OPEN },
+	{ "symref-verify", parse_cmd_symref_verify, 2, UPDATE_REFS_OPEN },
+	{ "option",        parse_cmd_option,        1, UPDATE_REFS_OPEN },
+	{ "start",         parse_cmd_start,         0, UPDATE_REFS_STARTED },
+	{ "prepare",       parse_cmd_prepare,       0, UPDATE_REFS_PREPARED },
+	{ "abort",         parse_cmd_abort,         0, UPDATE_REFS_CLOSED },
+	{ "commit",        parse_cmd_commit,        0, UPDATE_REFS_CLOSED },
 };
 
 static void update_refs_stdin(void)