fetch-pack: put shallow info in output parameter

Expand the transport fetch method signature, by adding an output
parameter, to allow transports to return information about the refs they
have fetched.  Then communicate shallow status information through this
mechanism instead of by modifying the input list of refs.

This does require clients to sometimes generate the ref map twice: once
from the list of refs provided by the remote (as is currently done) and
potentially once from the new list of refs that the fetch mechanism
provides.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 26 insertions, 6 deletions

diff --git a/builtin/clone.c b/builtin/clone.c
index 99e73dae85..8f86d99c51 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -1155,7 +1155,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 			}
 
 		if (!is_local && !complete_refs_before_fetch)
-			transport_fetch_refs(transport, mapped_refs);
+			transport_fetch_refs(transport, mapped_refs, NULL);
 
 		remote_head = find_ref_by_name(refs, "HEAD");
 		remote_head_points_at =
@@ -1197,7 +1197,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	if (is_local)
 		clone_local(path, git_dir);
 	else if (refs && complete_refs_before_fetch)
-		transport_fetch_refs(transport, mapped_refs);
+		transport_fetch_refs(transport, mapped_refs, NULL);
 
 	update_remote_refs(refs, mapped_refs, remote_head_points_at,
 			   branch_top.buf, reflog_msg.buf, transport,
diff --git a/builtin/fetch.c b/builtin/fetch.c
index bda00e8262..0347cf0167 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -946,11 +946,13 @@ static int quickfetch(struct ref *ref_map)
 	return check_connected(iterate_ref_map, &rm, &opt);
 }
 
-static int fetch_refs(struct transport *transport, struct ref *ref_map)
+static int fetch_refs(struct transport *transport, struct ref *ref_map,
+		      struct ref **updated_remote_refs)
 {
 	int ret = quickfetch(ref_map);
 	if (ret)
-		ret = transport_fetch_refs(transport, ref_map);
+		ret = transport_fetch_refs(transport, ref_map,
+					   updated_remote_refs);
 	if (!ret)
 		/*
 		 * Keep the new pack's ".keep" file around to allow the caller
@@ -1112,7 +1114,7 @@ static void backfill_tags(struct transport *transport, struct ref *ref_map)
 	transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, NULL);
 	transport_set_option(transport, TRANS_OPT_DEPTH, "0");
 	transport_set_option(transport, TRANS_OPT_DEEPEN_RELATIVE, NULL);
-	if (!fetch_refs(transport, ref_map))
+	if (!fetch_refs(transport, ref_map, NULL))
 		consume_refs(transport, ref_map);
 
 	if (gsecondary) {
@@ -1128,6 +1130,7 @@ static int do_fetch(struct transport *transport,
 	int autotags = (transport->remote->fetch_tags == 1);
 	int retcode = 0;
 	const struct ref *remote_refs;
+	struct ref *updated_remote_refs = NULL;
 	struct argv_array ref_prefixes = ARGV_ARRAY_INIT;
 
 	if (tags == TAGS_DEFAULT) {
@@ -1178,7 +1181,24 @@ static int do_fetch(struct transport *transport,
 				   transport->url);
 		}
 	}
-	if (fetch_refs(transport, ref_map) || consume_refs(transport, ref_map)) {
+
+	if (fetch_refs(transport, ref_map, &updated_remote_refs)) {
+		free_refs(ref_map);
+		retcode = 1;
+		goto cleanup;
+	}
+	if (updated_remote_refs) {
+		/*
+		 * Regenerate ref_map using the updated remote refs.  This is
+		 * to account for additional information which may be provided
+		 * by the transport (e.g. shallow info).
+		 */
+		free_refs(ref_map);
+		ref_map = get_ref_map(transport->remote, updated_remote_refs, rs,
+				      tags, &autotags);
+		free_refs(updated_remote_refs);
+	}
+	if (consume_refs(transport, ref_map)) {
 		free_refs(ref_map);
 		retcode = 1;
 		goto cleanup;