patch, 5 partsupload-pack: implement protocol extension "symbolic-ref"

diff --git a/t/t5601-clone.sh b/t/t5601-clone.sh
index 78a3fa6..6d4665b 100755
--- a/t/t5601-clone.sh
+++ b/t/t5601-clone.sh
@@ -125,4 +125,15 @@ test_expect_success 'clone to destination with extra trailing /' '
 
 '
 
+test_expect_success 'clone from a repository with two identical branches' '
+
+	(
+		cd src &&
+		git checkout -b another master
+	) &&
+	git clone src target-3 &&
+	test "z$( cd target-3 && git symbolic-ref HEAD )" = zrefs/heads/another
+
+'
+
 test_done

diff --git a/upload-pack.c b/upload-pack.c
index 4029019..a925f69 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -494,6 +494,23 @@ static void exchange_shallows(int depth, struct object_array *shallows)
 		}
 }
 
+static int one_symref_info(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
+{
+	if ((flag & REF_ISSYMREF)) {
+		unsigned char dummy[20];
+		const char *target = resolve_ref(refname, dummy, 0, NULL);
+		packet_write(1, "symref %s %s", refname, target);
+	}
+	return 0;
+}
+
+static void send_symref_info(void)
+{
+	head_ref(one_symref_info, NULL);
+	for_each_ref(one_symref_info, NULL);
+	packet_flush(1);
+}
+
 static void receive_needs(void)
 {
 	struct object_array shallows = {0, 0, NULL};
@@ -502,11 +519,29 @@ static void receive_needs(void)
 
 	if (debug_fd)
 		write_in_full(debug_fd, "#S\n", 3);
-	for (;;) {
+
+	/*
+	 * This is very unfortunate, but the "transport" abstraction
+	 * is screwed up and insists that getting the list of refs
+	 * to finish before actually sending the "needs" list from
+	 * the client end.
+	 */
+	len = packet_read_line(0, line, sizeof(line));
+	if (len) {
+		if (!prefixcmp(line, "symbolic-ref")) {
+			reset_timeout();
+			send_symref_info();
+			len = 0;
+		}
+	}
+	for (;; len = 0) {
 		struct object *o;
 		unsigned char sha1_buf[20];
-		len = packet_read_line(0, line, sizeof(line));
-		reset_timeout();
+
+		if (!len) {
+			len = packet_read_line(0, line, sizeof(line));
+			reset_timeout();
+		}
 		if (!len)
 			break;
 		if (debug_fd)
@@ -577,7 +612,7 @@ static void receive_needs(void)
 static int send_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
 {
 	static const char *capabilities = "multi_ack thin-pack side-band"
-		" side-band-64k ofs-delta shallow no-progress"
+		" side-band-64k ofs-delta shallow no-progress symbolic-ref"
 		" include-tag";
 	struct object *o = parse_object(sha1);
 

builtin-clone.c, connect.c

diff --git a/builtin-clone.c b/builtin-clone.c
index 2feac9c..a8b8d56 100644
--- a/builtin-clone.c
+++ b/builtin-clone.c
@@ -299,13 +299,27 @@ static const struct ref *locate_head(const struct ref *refs,
 	const struct ref *remote_head = NULL;
 	const struct ref *remote_master = NULL;
 	const struct ref *r;
-	for (r = refs; r; r = r->next)
-		if (!strcmp(r->name, "HEAD"))
+
+	for (r = refs; r; r = r->next) {
+		if (!strcmp(r->name, "HEAD")) {
 			remote_head = r;
+			break;
+		}
+	}
 
-	for (r = mapped_refs; r; r = r->next)
-		if (!strcmp(r->name, "refs/heads/master"))
-			remote_master = r;
+	if (remote_head && remote_head->symref) {
+		for (r = mapped_refs; r; r = r->next)
+			if (!strcmp(r->name, remote_head->symref)) {
+				remote_master = r;
+				break;
+			}
+	}
+
+	if (!remote_master) {
+		for (r = mapped_refs; r; r = r->next)
+			if (!strcmp(r->name, "refs/heads/master"))
+				remote_master = r;
+	}
 
 	if (remote_head_p)
 		*remote_head_p = remote_head;
diff --git a/connect.c b/connect.c
index 402fbe6..40b43b4 100644
--- a/connect.c
+++ b/connect.c
@@ -48,6 +48,39 @@ static void add_extra_have(struct extra_have_objects *extra, unsigned char *sha1
 	extra->nr++;
 }
 
+static void receive_symref(int fd[2], struct ref *refs)
+{
+	char line[1024];
+	int len;
+
+	packet_write(fd[1], "symbolic-ref");
+	while ((len = packet_read_line(fd[0], line, sizeof(line)))) {
+		if (!prefixcmp(line, "symref ")) {
+			struct ref *sym;
+			char *symref = line + 7;
+			char *target = strchr(symref, ' ');
+			if (!target)
+				die("Malformed symref line %s", line);
+			*target++ = '\0';
+			sym = find_ref_by_name(refs, symref);
+			if (!sym) {
+				/*
+				 * NEEDSWORK: perhaps create the symref ref
+				 * that is still unborn and queue it?
+				 */
+				continue;
+			}
+			if (sym->symref)
+				die("symref line says %s points at %s "
+				    "but earlier it said it points at %s",
+				    symref, target, sym->symref);
+			sym->symref = xstrdup(target);
+			continue;
+		}
+		die("expected symref, got %s", line);
+	}
+}
+
 /*
  * Read all the refs from the other end
  */
@@ -56,6 +89,7 @@ struct ref **get_remote_heads(int fd[2], struct ref **list,
 			      unsigned int flags,
 			      struct extra_have_objects *extra_have)
 {
+	struct ref **original_list = list;
 	*list = NULL;
 	for (;;) {
 		struct ref *ref;
@@ -98,6 +132,8 @@ struct ref **get_remote_heads(int fd[2], struct ref **list,
 		*list = ref;
 		list = &ref->next;
 	}
+	if (server_supports("symbolic-ref"))
+		receive_symref(fd, *original_list);
 	return list;
 }
 

builtin-fetch-pack.c, builtin-send-pack.c, cache.h, connect.c, transport.c

diff --git a/builtin-fetch-pack.c b/builtin-fetch-pack.c
index 372bfa2..6927410 100644
--- a/builtin-fetch-pack.c
+++ b/builtin-fetch-pack.c
@@ -735,7 +735,7 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 	conn = git_connect(fd, (char *)dest, args.uploadpack,
 			   args.verbose ? CONNECT_VERBOSE : 0);
 	if (conn) {
-		get_remote_heads(fd[0], &ref, 0, NULL, 0, NULL);
+		get_remote_heads(fd, &ref, 0, NULL, 0, NULL);
 
 		ref = fetch_pack(&args, fd, conn, ref, dest, nr_heads, heads, NULL);
 		close(fd[0]);
diff --git a/builtin-send-pack.c b/builtin-send-pack.c
index a9fdbf9..23cdd48 100644
--- a/builtin-send-pack.c
+++ b/builtin-send-pack.c
@@ -386,7 +386,7 @@ static int refs_pushed(struct ref *ref)
 	return 0;
 }
 
-static int do_send_pack(int in, int out, struct remote *remote, const char *dest, int nr_refspec, const char **refspec)
+static int do_send_pack(int fd[2], struct remote *remote, const char *dest, int nr_refspec, const char **refspec)
 {
 	struct ref *ref;
 	int new_refs;
@@ -395,6 +395,7 @@ static int do_send_pack(int in, int out, struct remote *remote, const char *dest
 	int expect_status_report = 0;
 	int flags = MATCH_REFS_NONE;
 	int ret;
+	int in = fd[0], out = fd[1];
 	struct extra_have_objects extra_have;
 
 	memset(&extra_have, 0, sizeof(extra_have));
@@ -404,7 +405,7 @@ static int do_send_pack(int in, int out, struct remote *remote, const char *dest
 		flags |= MATCH_REFS_MIRROR;
 
 	/* No funny business with the matcher */
-	remote_tail = get_remote_heads(in, &remote_refs, 0, NULL, REF_NORMAL,
+	remote_tail = get_remote_heads(fd, &remote_refs, 0, NULL, REF_NORMAL,
 				       &extra_have);
 	get_local_heads();
 
@@ -665,7 +666,7 @@ int send_pack(struct send_pack_args *my_args,
 	verify_remote_names(nr_heads, heads);
 
 	conn = git_connect(fd, dest, args.receivepack, args.verbose ? CONNECT_VERBOSE : 0);
-	ret = do_send_pack(fd[0], fd[1], remote, dest, nr_heads, heads);
+	ret = do_send_pack(fd, remote, dest, nr_heads, heads);
 	close(fd[0]);
 	/* do_send_pack always closes fd[1] */
 	ret |= finish_connect(conn);
diff --git a/cache.h b/cache.h
index 487e5e1..2bee869 100644
--- a/cache.h
+++ b/cache.h
@@ -752,7 +752,7 @@ struct extra_have_objects {
 	int nr, alloc;
 	unsigned char (*array)[20];
 };
-extern struct ref **get_remote_heads(int in, struct ref **list, int nr_match, char **match, unsigned int flags, struct extra_have_objects *);
+extern struct ref **get_remote_heads(int fd[2], struct ref **list, int nr_match, char **match, unsigned int flags, struct extra_have_objects *);
 extern int server_supports(const char *feature);
 
 extern struct packed_git *parse_pack_index(unsigned char *sha1);
diff --git a/connect.c b/connect.c
index 584e04c..402fbe6 100644
--- a/connect.c
+++ b/connect.c
@@ -51,7 +51,7 @@ static void add_extra_have(struct extra_have_objects *extra, unsigned char *sha1
 /*
  * Read all the refs from the other end
  */
-struct ref **get_remote_heads(int in, struct ref **list,
+struct ref **get_remote_heads(int fd[2], struct ref **list,
 			      int nr_match, char **match,
 			      unsigned int flags,
 			      struct extra_have_objects *extra_have)
@@ -64,7 +64,7 @@ struct ref **get_remote_heads(int in, struct ref **list,
 		char *name;
 		int len, name_len;
 
-		len = packet_read_line(in, buffer, sizeof(buffer));
+		len = packet_read_line(fd[0], buffer, sizeof(buffer));
 		if (!len)
 			break;
 		if (buffer[len-1] == '\n')
diff --git a/transport.c b/transport.c
index 56831c5..72b3a76 100644
--- a/transport.c
+++ b/transport.c
@@ -617,7 +617,7 @@ static struct ref *get_refs_via_connect(struct transport *transport)
 	struct ref *refs;
 
 	connect_setup(transport);
-	get_remote_heads(data->fd[0], &refs, 0, NULL, 0, NULL);
+	get_remote_heads(data->fd, &refs, 0, NULL, 0, NULL);
 
 	return refs;
 }
@@ -650,7 +650,7 @@ static int fetch_refs_via_pack(struct transport *transport,
 
 	if (!data->conn) {
 		connect_setup(transport);
-		get_remote_heads(data->fd[0], &refs_tmp, 0, NULL, 0, NULL);
+		get_remote_heads(data->fd, &refs_tmp, 0, NULL, 0, NULL);
 	}
 
 	refs = fetch_pack(&args, data->fd, data->conn,

diff --git a/upload-pack.c b/upload-pack.c
index e5adbc0..4029019 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -444,6 +444,56 @@ static int get_common_commits(void)
 	}
 }
 
+static void exchange_shallows(int depth, struct object_array *shallows)
+{
+	if (depth == 0 && shallows->nr == 0)
+		return;
+	if (depth > 0) {
+		struct commit_list *result, *backup;
+		int i;
+		backup = result = get_shallow_commits(&want_obj, depth,
+			SHALLOW, NOT_SHALLOW);
+		while (result) {
+			struct object *object = &result->item->object;
+			if (!(object->flags & (CLIENT_SHALLOW|NOT_SHALLOW))) {
+				packet_write(1, "shallow %s",
+						sha1_to_hex(object->sha1));
+				register_shallow(object->sha1);
+			}
+			result = result->next;
+		}
+		free_commit_list(backup);
+		for (i = 0; i < shallows->nr; i++) {
+			struct object *object = shallows->objects[i].item;
+			if (object->flags & NOT_SHALLOW) {
+				struct commit_list *parents;
+				packet_write(1, "unshallow %s",
+					sha1_to_hex(object->sha1));
+				object->flags &= ~CLIENT_SHALLOW;
+				/* make sure the real parents are parsed */
+				unregister_shallow(object->sha1);
+				object->parsed = 0;
+				if (parse_commit((struct commit *)object))
+					die("invalid commit");
+				parents = ((struct commit *)object)->parents;
+				while (parents) {
+					add_object_array(&parents->item->object,
+							NULL, &want_obj);
+					parents = parents->next;
+				}
+			}
+			/* make sure commit traversal conforms to client */
+			register_shallow(object->sha1);
+		}
+		packet_flush(1);
+	} else
+		if (shallows->nr > 0) {
+			int i;
+			for (i = 0; i < shallows->nr; i++)
+				register_shallow(shallows->objects[i].item->sha1);
+		}
+}
+
 static void receive_needs(void)
 {
 	struct object_array shallows = {0, 0, NULL};
@@ -520,52 +570,7 @@ static void receive_needs(void)
 	}
 	if (debug_fd)
 		write_in_full(debug_fd, "#E\n", 3);
-	if (depth == 0 && shallows.nr == 0)
-		return;
-	if (depth > 0) {
-		struct commit_list *result, *backup;
-		int i;
-		backup = result = get_shallow_commits(&want_obj, depth,
-			SHALLOW, NOT_SHALLOW);
-		while (result) {
-			struct object *object = &result->item->object;
-			if (!(object->flags & (CLIENT_SHALLOW|NOT_SHALLOW))) {
-				packet_write(1, "shallow %s",
-						sha1_to_hex(object->sha1));
-				register_shallow(object->sha1);
-			}
-			result = result->next;
-		}
-		free_commit_list(backup);
-		for (i = 0; i < shallows.nr; i++) {
-			struct object *object = shallows.objects[i].item;
-			if (object->flags & NOT_SHALLOW) {
-				struct commit_list *parents;
-				packet_write(1, "unshallow %s",
-					sha1_to_hex(object->sha1));
-				object->flags &= ~CLIENT_SHALLOW;
-				/* make sure the real parents are parsed */
-				unregister_shallow(object->sha1);
-				object->parsed = 0;
-				if (parse_commit((struct commit *)object))
-					die("invalid commit");
-				parents = ((struct commit *)object)->parents;
-				while (parents) {
-					add_object_array(&parents->item->object,
-							NULL, &want_obj);
-					parents = parents->next;
-				}
-			}
-			/* make sure commit traversal conforms to client */
-			register_shallow(object->sha1);
-		}
-		packet_flush(1);
-	} else
-		if (shallows.nr > 0) {
-			int i;
-			for (i = 0; i < shallows.nr; i++)
-				register_shallow(shallows.objects[i].item->sha1);
-		}
+	exchange_shallows(depth, &shallows);
 	free(shallows.objects);
 }
 

diff --git c/git-send-email.perl w/git-send-email.perl
index 7508f8f..45beb9c 100755
--- c/git-send-email.perl
+++ w/git-send-email.perl
@@ -421,7 +421,7 @@ EOF
 # Now that all the defaults are set, process the rest of the command line
 # arguments and collect up the files that need to be processed.
 my @rev_list_opts;
-while (my $f = pop @ARGV) {
+while (defined(my $f = shift @ARGV)) {
 	if ($f eq "--") {
 		push @rev_list_opts, "--", @ARGV;
 		@ARGV = ();