Merge branch 'jk/fix-proto-downgrade-to-v0'

Transports that do not support protocol v2 did not correctly fall
back to protocol v0 under certain conditions, which has been
corrected.

* jk/fix-proto-downgrade-to-v0:
  git_connect(): fix corner cases in downgrading v2 to v0

builtin/fetch-pack.c

@@ -213,8 +213,8 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 		int flags = args.verbose ? CONNECT_VERBOSE : 0;
 		if (args.diag_url)
 			flags |= CONNECT_DIAG_URL;
-		conn = git_connect(fd, dest, args.uploadpack,
-				   flags);
+		conn = git_connect(fd, dest, "git-upload-pack",
+				   args.uploadpack, flags);
 		if (!conn)
 			return args.diag_url ? 0 : 1;
 	}

builtin/send-pack.c

@@ -274,7 +274,7 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix)
 		fd[0] = 0;
 		fd[1] = 1;
 	} else {
-		conn = git_connect(fd, dest, receivepack,
+		conn = git_connect(fd, dest, "git-receive-pack", receivepack,
 			args.verbose ? CONNECT_VERBOSE : 0);
 	}
 

connect.c

@@ -1408,6 +1408,7 @@ static void fill_ssh_args(struct child_process *conn, const char *ssh_host,
  * the connection failed).
  */
 struct child_process *git_connect(int fd[2], const char *url,
+				  const char *name,
 				  const char *prog, int flags)
 {
 	char *hostandport, *path;
@@ -1417,10 +1418,11 @@ struct child_process *git_connect(int fd[2], const char *url,
 
 	/*
 	 * NEEDSWORK: If we are trying to use protocol v2 and we are planning
-	 * to perform a push, then fallback to v0 since the client doesn't know
-	 * how to push yet using v2.
+	 * to perform any operation that doesn't involve upload-pack (i.e., a
+	 * fetch, ls-remote, etc), then fallback to v0 since we don't know how
+	 * to do anything else (like push or remote archive) via v2.
 	 */
-	if (version == protocol_v2 && !strcmp("git-receive-pack", prog))
+	if (version == protocol_v2 && strcmp("git-upload-pack", name))
 		version = protocol_v0;
 
 	/* Without this we cannot rely on waitpid() to tell

connect.h

@@ -7,7 +7,7 @@
 #define CONNECT_DIAG_URL      (1u << 1)
 #define CONNECT_IPV4          (1u << 2)
 #define CONNECT_IPV6          (1u << 3)
-struct child_process *git_connect(int fd[2], const char *url, const char *prog, int flags);
+struct child_process *git_connect(int fd[2], const char *url, const char *name, const char *prog, int flags);
 int finish_connect(struct child_process *conn);
 int git_connection_is_socket(struct child_process *conn);
 int server_supports(const char *feature);

remote-curl.c

@@ -474,10 +474,11 @@ static struct discovery *discover_refs(const char *service, int for_push)
 
 	/*
 	 * NEEDSWORK: If we are trying to use protocol v2 and we are planning
-	 * to perform a push, then fallback to v0 since the client doesn't know
-	 * how to push yet using v2.
+	 * to perform any operation that doesn't involve upload-pack (i.e., a
+	 * fetch, ls-remote, etc), then fallback to v0 since we don't know how
+	 * to do anything else (like push or remote archive) via v2.
 	 */
-	if (version == protocol_v2 && !strcmp("git-receive-pack", service))
+	if (version == protocol_v2 && strcmp("git-upload-pack", service))
 		version = protocol_v0;
 
 	/* Add the extra Git-Protocol header */

t/t5702-protocol-v2.sh

@@ -728,6 +728,33 @@ test_expect_success 'file:// --negotiate-only with protocol v0' '
 	test_i18ngrep "negotiate-only requires protocol v2" err
 '
 
+test_expect_success 'push with custom path does not request v2' '
+	rm -f env.trace &&
+	git -C client push \
+		--receive-pack="env >../env.trace; git-receive-pack" \
+		origin HEAD:refs/heads/custom-push-test &&
+	test_path_is_file env.trace &&
+	! grep ^GIT_PROTOCOL env.trace
+'
+
+test_expect_success 'fetch with custom path does request v2' '
+	rm -f env.trace &&
+	git -C client fetch \
+		--upload-pack="env >../env.trace; git-upload-pack" \
+		origin HEAD &&
+	grep ^GIT_PROTOCOL=version=2 env.trace
+'
+
+test_expect_success 'archive with custom path does not request v2' '
+	rm -f env.trace &&
+	git -C client archive \
+		--exec="env >../env.trace; git-upload-archive" \
+		--remote=origin \
+		HEAD >/dev/null &&
+	test_path_is_file env.trace &&
+	! grep ^GIT_PROTOCOL env.trace
+'
+
 # Test protocol v2 with 'http://' transport
 #
 . "$TEST_DIRECTORY"/lib-httpd.sh

transport.c

@@ -279,8 +279,12 @@ static int connect_setup(struct transport *transport, int for_push)
 	}
 
 	data->conn = git_connect(data->fd, transport->url,
-				 for_push ? data->options.receivepack :
-				 data->options.uploadpack,
+				 for_push ?
+					"git-receive-pack" :
+					"git-upload-pack",
+				 for_push ?
+					data->options.receivepack :
+					data->options.uploadpack,
 				 flags);
 
 	return 0;
@@ -914,7 +918,7 @@ static int connect_git(struct transport *transport, const char *name,
 {
 	struct git_transport_data *data = transport->data;
 	data->conn = git_connect(data->fd, transport->url,
-				 executable, 0);
+				 name, executable, 0);
 	fd[0] = data->fd[0];
 	fd[1] = data->fd[1];
 	return 0;