clone: introduce struct clone_opts in builtin/clone.c

There is a lot of state stored in global variables in builtin/clone.c.
In the long run we'd like to remove many of those.

Introduce `struct clone_opts` in this file. This struct will be used to
contain all details needed to perform the clone. The struct object can
be thrown around to all the functions that need these details.

The first field we're adding is `wants_head`. In some scenarios
(specifically when both `--single-branch` and `--branch` are given) we
are not interested in `HEAD` on the remote. The field `wants_head` in
`struct clone_opts` will hold this information. We could have put
`option_branch` and `option_single_branch` into that struct instead, but
in a following commit we'll be using `wants_head` as well.

Signed-off-by: Toon Claes <toon@iotcl.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: To1ne

builtin/clone.c

@@ -57,6 +57,13 @@
  *
  */
 
+struct clone_opts {
+	int wants_head;
+};
+#define CLONE_OPTS_INIT { \
+	.wants_head = 1 /* default enabled */ \
+}
+
 static int option_no_checkout, option_bare, option_mirror, option_single_branch = -1;
 static int option_local = -1, option_no_hardlinks, option_shared;
 static int option_tags = 1; /* default enabled */
@@ -429,23 +436,24 @@ static struct ref *find_remote_branch(const struct ref *refs, const char *branch
 	return ref;
 }
 
-static struct ref *wanted_peer_refs(const struct ref *refs,
-		struct refspec *refspec)
+static struct ref *wanted_peer_refs(struct clone_opts *opts,
+				    const struct ref *refs,
+				    struct refspec *refspec)
 {
-	struct ref *head = copy_ref(find_ref_by_name(refs, "HEAD"));
-	struct ref *local_refs = head;
-	struct ref **tail = local_refs ? &local_refs->next : &local_refs;
+	struct ref *local_refs = NULL;
+	struct ref **tail = &local_refs;
 	struct ref *to_free = NULL;
 
-	if (option_single_branch) {
-		if (!option_branch)
+	if (opts->wants_head) {
+		struct ref *head = copy_ref(find_ref_by_name(refs, "HEAD"));
+		if (head)
+			tail_link_ref(head, &tail);
+		if (option_single_branch)
 			refs = to_free = guess_remote_head(head, refs, 0);
-		else {
-			free_one_ref(head);
-			local_refs = head = NULL;
-			tail = &local_refs;
-			refs = to_free = copy_ref(find_remote_branch(refs, option_branch));
-		}
+	} else if (option_single_branch) {
+		local_refs = NULL;
+		tail = &local_refs;
+		refs = to_free = copy_ref(find_remote_branch(refs, option_branch));
 	}
 
 	for (size_t i = 0; i < refspec->nr; i++)
@@ -893,6 +901,8 @@ int cmd_clone(int argc,
 	struct string_list server_options = STRING_LIST_INIT_NODUP;
 	const char *bundle_uri = NULL;
 
+	struct clone_opts opts = CLONE_OPTS_INIT;
+
 	struct transport_ls_refs_options transport_ls_refs_options =
 		TRANSPORT_LS_REFS_OPTIONS_INIT;
 
@@ -1343,9 +1353,13 @@ int cmd_clone(int argc,
 	if (option_not.nr)
 		transport_set_option(transport, TRANS_OPT_DEEPEN_NOT,
 				     (const char *)&option_not);
-	if (option_single_branch)
+	if (option_single_branch) {
 		transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");
 
+		if (option_branch)
+			opts.wants_head = 0;
+	}
+
 	if (option_upload_pack)
 		transport_set_option(transport, TRANS_OPT_UPLOADPACK,
 				     option_upload_pack);
@@ -1454,7 +1468,7 @@ int cmd_clone(int argc,
 	}
 
 	if (refs)
-		mapped_refs = wanted_peer_refs(refs, &remote->fetch);
+		mapped_refs = wanted_peer_refs(&opts, refs, &remote->fetch);
 
 	if (mapped_refs) {
 		/*

remote.c

@@ -1234,7 +1234,7 @@ int count_refspec_match(const char *pattern,
 	}
 }
 
-static void tail_link_ref(struct ref *ref, struct ref ***tail)
+void tail_link_ref(struct ref *ref, struct ref ***tail)
 {
 	**tail = ref;
 	while (ref->next)

remote.h

@@ -219,6 +219,11 @@ struct ref *alloc_ref(const char *name);
 struct ref *copy_ref(const struct ref *ref);
 struct ref *copy_ref_list(const struct ref *ref);
 int count_refspec_match(const char *, struct ref *refs, struct ref **matched_ref);
+/*
+ * Put a ref in the tail and prepare tail for adding another one.
+ * *tail is the pointer to the tail of the list of refs.
+ */
+void tail_link_ref(struct ref *ref, struct ref ***tail);
 
 int check_ref_type(const struct ref *ref, int flags);