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, 13 insertions, 9 deletions

diff --git a/connect.c b/connect.c
index c763eeda8..4150412e2 100644
--- a/connect.c
+++ b/connect.c
@@ -8,6 +8,7 @@
 #include "connect.h"
 #include "url.h"
 #include "string-list.h"
+#include "sha1-array.h"
 
 static char *server_capabilities;
 static const char *parse_feature_value(const char *, const char *, int *);
@@ -45,13 +46,6 @@ int check_ref_type(const struct ref *ref, int flags)
 	return check_ref(ref->name, strlen(ref->name), flags);
 }
 
-static void add_extra_have(struct extra_have_objects *extra, unsigned char *sha1)
-{
-	ALLOC_GROW(extra->array, extra->nr + 1, extra->alloc);
-	hashcpy(&(extra->array[extra->nr][0]), sha1);
-	extra->nr++;
-}
-
 static void die_initial_contact(int got_at_least_one_head)
 {
 	if (got_at_least_one_head)
@@ -122,7 +116,8 @@ static void annotate_refs_with_symref_info(struct ref *ref)
  */
 struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 			      struct ref **list, unsigned int flags,
-			      struct extra_have_objects *extra_have)
+			      struct sha1_array *extra_have,
+			      struct sha1_array *shallow_points)
 {
 	struct ref **orig_list = list;
 	int got_at_least_one_head = 0;
@@ -148,6 +143,15 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 		if (len > 4 && starts_with(buffer, "ERR "))
 			die("remote error: %s", buffer + 4);
 
+		if (len == 48 && starts_with(buffer, "shallow ")) {
+			if (get_sha1_hex(buffer + 8, old_sha1))
+				die("protocol error: expected shallow sha-1, got '%s'", buffer + 8);
+			if (!shallow_points)
+				die("repository on the other end cannot be shallow");
+			sha1_array_append(shallow_points, old_sha1);
+			continue;
+		}
+
 		if (len < 42 || get_sha1_hex(buffer, old_sha1) || buffer[40] != ' ')
 			die("protocol error: expected sha/ref, got '%s'", buffer);
 		name = buffer + 41;
@@ -160,7 +164,7 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 
 		if (extra_have &&
 		    name_len == 5 && !memcmp(".have", name, 5)) {
-			add_extra_have(extra_have, old_sha1);
+			sha1_array_append(extra_have, old_sha1);
 			continue;
 		}