send-pack: do not send unknown object name from ".have" to pack-objects

v1.6.1 introduced ".have" extension to the protocol to allow the receiving
side to advertise objects that are reachable from refs in the repositories
it borrows from.  This was meant to be used by the sending side to avoid
sending such objects; they are already available through the alternates
mechanism.

The client side implementation in v1.6.1, which was introduced with
40c155f (push: prepare sender to receive extended ref information from the
receiver, 2008-09-09) aka v1.6.1-rc1~203^2~1, were faulty in that it did
not consider the possiblity that the repository receiver borrows from
might have objects it does not know about.

This fixes it by refraining from passing missing commits to underlying
pack-objects.  Revision machinery may need to be tightened further to
treat missing uninteresting objects as non-error events, but this is an
obvious and safe fix for a maintenance release that is almost good enough.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 21 insertions, 22 deletions

diff --git a/builtin-send-pack.c b/builtin-send-pack.c
index a9fdbf9d45..d65d019692 100644
--- a/builtin-send-pack.c
+++ b/builtin-send-pack.c
@@ -15,6 +15,20 @@ static struct send_pack_args args = {
 	/* .receivepack = */ "git-receive-pack",
 };
 
+static int feed_object(const unsigned char *sha1, int fd, int negative)
+{
+	char buf[42];
+
+	if (negative && !has_sha1_file(sha1))
+		return 1;
+
+	memcpy(buf + negative, sha1_to_hex(sha1), 40);
+	if (negative)
+		buf[0] = '^';
+	buf[40 + negative] = '\n';
+	return write_or_whine(fd, buf, 41 + negative, "send-pack: send refs");
+}
+
 /*
  * Make a pack stream and spit it out into file descriptor fd
  */
@@ -35,7 +49,6 @@ static int pack_objects(int fd, struct ref *refs, struct extra_have_objects *ext
 	};
 	struct child_process po;
 	int i;
-	char buf[42];
 
 	if (args.use_thin_pack)
 		argv[4] = "--thin";
@@ -51,31 +64,17 @@ static int pack_objects(int fd, struct ref *refs, struct extra_have_objects *ext
 	 * We feed the pack-objects we just spawned with revision
 	 * parameters by writing to the pipe.
 	 */
-	for (i = 0; i < extra->nr; i++) {
-		memcpy(buf + 1, sha1_to_hex(&extra->array[i][0]), 40);
-		buf[0] = '^';
-		buf[41] = '\n';
-		if (!write_or_whine(po.in, buf, 42, "send-pack: send refs"))
+	for (i = 0; i < extra->nr; i++)
+		if (!feed_object(extra->array[i], po.in, 1))
 			break;
-	}
 
 	while (refs) {
 		if (!is_null_sha1(refs->old_sha1) &&
-		    has_sha1_file(refs->old_sha1)) {
-			memcpy(buf + 1, sha1_to_hex(refs->old_sha1), 40);
-			buf[0] = '^';
-			buf[41] = '\n';
-			if (!write_or_whine(po.in, buf, 42,
-						"send-pack: send refs"))
-				break;
-		}
-		if (!is_null_sha1(refs->new_sha1)) {
-			memcpy(buf, sha1_to_hex(refs->new_sha1), 40);
-			buf[40] = '\n';
-			if (!write_or_whine(po.in, buf, 41,
-						"send-pack: send refs"))
-				break;
-		}
+		    !feed_object(refs->old_sha1, po.in, 1))
+			break;
+		if (!is_null_sha1(refs->new_sha1) &&
+		    !feed_object(refs->new_sha1, po.in, 0))
+			break;
 		refs = refs->next;
 	}