Merge branch 'nd/shallow-clone'

Fetching from a shallow-cloned repository used to be forbidden,
primarily because the codepaths involved were not carefully vetted
and we did not bother supporting such usage. This attempts to allow
object transfer out of a shallow-cloned repository in a controlled
way (i.e. the receiver become a shallow repository with truncated
history).

* nd/shallow-clone: (31 commits)
  t5537: fix incorrect expectation in test case 10
  shallow: remove unused code
  send-pack.c: mark a file-local function static
  git-clone.txt: remove shallow clone limitations
  prune: clean .git/shallow after pruning objects
  clone: use git protocol for cloning shallow repo locally
  send-pack: support pushing from a shallow clone via http
  receive-pack: support pushing to a shallow clone via http
  smart-http: support shallow fetch/clone
  remote-curl: pass ref SHA-1 to fetch-pack as well
  send-pack: support pushing to a shallow clone
  receive-pack: allow pushes that update .git/shallow
  connected.c: add new variant that runs with --shallow-file
  add GIT_SHALLOW_FILE to propagate --shallow-file to subprocesses
  receive/send-pack: support pushing from a shallow clone
  receive-pack: reorder some code in unpack()
  fetch: add --update-shallow to accept refs that update .git/shallow
  upload-pack: make sure deepening preserves shallow roots
  fetch: support fetching from a shallow repository
  clone: support remote shallow repository
  ...

1 files changed, 20 insertions, 5 deletions

diff --git a/transport.c b/transport.c
index 824c5b93f9..ca7bb441bf 100644
--- a/transport.c
+++ b/transport.c
@@ -14,6 +14,7 @@
 #include "url.h"
 #include "submodule.h"
 #include "string-list.h"
+#include "sha1-array.h"
 
 /* rsync support */
 
@@ -454,7 +455,8 @@ struct git_transport_data {
 	struct child_process *conn;
 	int fd[2];
 	unsigned got_remote_heads : 1;
-	struct extra_have_objects extra_have;
+	struct sha1_array extra_have;
+	struct sha1_array shallow;
 };
 
 static int set_git_option(struct git_transport_options *opts,
@@ -475,6 +477,9 @@ static int set_git_option(struct git_transport_options *opts,
 	} else if (!strcmp(name, TRANS_OPT_KEEP)) {
 		opts->keep = !!value;
 		return 0;
+	} else if (!strcmp(name, TRANS_OPT_UPDATE_SHALLOW)) {
+		opts->update_shallow = !!value;
+		return 0;
 	} else if (!strcmp(name, TRANS_OPT_DEPTH)) {
 		if (!value)
 			opts->depth = 0;
@@ -511,7 +516,9 @@ static struct ref *get_refs_via_connect(struct transport *transport, int for_pus
 
 	connect_setup(transport, for_push, 0);
 	get_remote_heads(data->fd[0], NULL, 0, &refs,
-			 for_push ? REF_NORMAL : 0, &data->extra_have);
+			 for_push ? REF_NORMAL : 0,
+			 &data->extra_have,
+			 &data->shallow);
 	data->got_remote_heads = 1;
 
 	return refs;
@@ -538,16 +545,19 @@ static int fetch_refs_via_pack(struct transport *transport,
 	args.depth = data->options.depth;
 	args.check_self_contained_and_connected =
 		data->options.check_self_contained_and_connected;
+	args.cloning = transport->cloning;
+	args.update_shallow = data->options.update_shallow;
 
 	if (!data->got_remote_heads) {
 		connect_setup(transport, 0, 0);
-		get_remote_heads(data->fd[0], NULL, 0, &refs_tmp, 0, NULL);
+		get_remote_heads(data->fd[0], NULL, 0, &refs_tmp, 0,
+				 NULL, &data->shallow);
 		data->got_remote_heads = 1;
 	}
 
 	refs = fetch_pack(&args, data->fd, data->conn,
 			  refs_tmp ? refs_tmp : transport->remote_refs,
-			  dest, to_fetch, nr_heads,
+			  dest, to_fetch, nr_heads, &data->shallow,
 			  &transport->pack_lockfile);
 	close(data->fd[0]);
 	close(data->fd[1]);
@@ -713,6 +723,10 @@ static int print_one_push_status(struct ref *ref, const char *dest, int count, i
 		print_ref_status('!', "[rejected]", ref, ref->peer_ref,
 						 "stale info", porcelain);
 		break;
+	case REF_STATUS_REJECT_SHALLOW:
+		print_ref_status('!', "[rejected]", ref, ref->peer_ref,
+						 "new shallow roots not allowed", porcelain);
+		break;
 	case REF_STATUS_REMOTE_REJECT:
 		print_ref_status('!', "[remote rejected]", ref,
 						 ref->deletion ? NULL : ref->peer_ref,
@@ -805,7 +819,8 @@ static int git_transport_push(struct transport *transport, struct ref *remote_re
 		struct ref *tmp_refs;
 		connect_setup(transport, 1, 0);
 
-		get_remote_heads(data->fd[0], NULL, 0, &tmp_refs, REF_NORMAL, NULL);
+		get_remote_heads(data->fd[0], NULL, 0, &tmp_refs, REF_NORMAL,
+				 NULL, &data->shallow);
 		data->got_remote_heads = 1;
 	}