transport.c:🤝 make use of server options from remote

Utilize the `server_options` from the corresponding remote during the
handshake in `transport.c` when Git protocol v2 is detected. This helps
initialize the `server_options` in `transport.h:transport` if no server
options are set for the transport (typically via `--server-option` or
`-o`).

While another potential place to incorporate server options from the
remote is in `transport.c:transport_get`, setting server options for a
transport using a protocol other than v2 could lead to unexpected errors
(see `transport.c:die_if_server_options`).

Relevant tests and documentation have been updated accordingly.

Signed-off-by: Xing Xin <xingxin.xx@bytedance.com>
Reviewed-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/fetch-options.txt

@@ -305,6 +305,9 @@ endif::git-pull[]
 	unknown ones, is server-specific.
 	When multiple `--server-option=<option>` are given, they are all
 	sent to the other side in the order listed on the command line.
+	When no `--server-option=<option>` is given from the command line,
+	the values of configuration variable `remote.<name>.serverOption`
+	are used instead.
 
 --show-forced-updates::
 	By default, git checks if a branch is force-updated during

Documentation/git-clone.txt

@@ -149,6 +149,9 @@ objects from the source repository into a pack in the cloned repository.
 	unknown ones, is server-specific.
 	When multiple ++--server-option=++__<option>__ are given, they are all
 	sent to the other side in the order listed on the command line.
+	When no ++--server-option=++__<option>__ is given from the command
+	line, the values of configuration variable `remote.<name>.serverOption`
+	are used instead.
 
 `-n`::
 `--no-checkout`::

Documentation/git-ls-remote.txt

@@ -81,6 +81,9 @@ OPTIONS
 	character.
 	When multiple `--server-option=<option>` are given, they are all
 	sent to the other side in the order listed on the command line.
+	When no `--server-option=<option>` is given from the command line,
+	the values of configuration variable `remote.<name>.serverOption`
+	are used instead.
 
 <repository>::
 	The "remote" repository to query.  This parameter can be

t/t5702-protocol-v2.sh

@@ -185,6 +185,43 @@ test_expect_success 'server-options are sent when using ls-remote' '
 	grep "server-option=world" log
 '
 
+test_expect_success 'server-options from configuration are used by ls-remote' '
+	test_when_finished "rm -rf log myclone" &&
+	git clone "file://$(pwd)/file_parent" myclone &&
+	cat >expect <<-EOF &&
+	$(git -C file_parent rev-parse refs/heads/main)$(printf "\t")refs/heads/main
+	EOF
+
+	# Default server options from configuration are used
+	git -C myclone config --add remote.origin.serverOption foo &&
+	git -C myclone config --add remote.origin.serverOption bar &&
+	GIT_TRACE_PACKET="$(pwd)/log" git -C myclone -c protocol.version=2 \
+		ls-remote origin main >actual &&
+	test_cmp expect actual &&
+	test_grep "ls-remote> server-option=foo" log &&
+	test_grep "ls-remote> server-option=bar" log &&
+	rm -f log &&
+
+	# Empty value of remote.<name>.serverOption clears the list
+	git -C myclone config --add remote.origin.serverOption "" &&
+	git -C myclone config --add remote.origin.serverOption tar &&
+	GIT_TRACE_PACKET="$(pwd)/log" git -C myclone -c protocol.version=2 \
+		ls-remote origin main >actual &&
+	test_cmp expect actual &&
+	test_grep "ls-remote> server-option=tar" log &&
+	test_grep ! "ls-remote> server-option=foo" log &&
+	test_grep ! "ls-remote> server-option=bar" log &&
+	rm -f log &&
+
+	# Server option from command line overrides those from configuration
+	GIT_TRACE_PACKET="$(pwd)/log" git -C myclone -c protocol.version=2 \
+		ls-remote -o hello -o world origin main >actual &&
+	test_cmp expect actual &&
+	test_grep "ls-remote> server-option=hello" log &&
+	test_grep "ls-remote> server-option=world" log &&
+	test_grep ! "ls-remote> server-option=tar" log
+'
+
 test_expect_success 'warn if using server-option with ls-remote with legacy protocol' '
 	test_must_fail env GIT_TEST_PROTOCOL_VERSION=0 git -c protocol.version=0 \
 		ls-remote -o hello -o world "file://$(pwd)/file_parent" main 2>err &&
@@ -381,6 +418,44 @@ test_expect_success 'server-options are sent when fetching' '
 	grep "server-option=world" log
 '
 
+test_expect_success 'server-options from configuration are used by git-fetch' '
+	test_when_finished "rm -rf log myclone" &&
+	git clone "file://$(pwd)/file_parent" myclone &&
+	git -C file_parent log -1 --format=%s >expect &&
+
+	# Default server options from configuration are used
+	git -C myclone config --add remote.origin.serverOption foo &&
+	git -C myclone config --add remote.origin.serverOption bar &&
+	GIT_TRACE_PACKET="$(pwd)/log" git -C myclone -c protocol.version=2 \
+		fetch origin main &&
+	git -C myclone log -1 --format=%s origin/main >actual &&
+	test_cmp expect actual &&
+	test_grep "fetch> server-option=foo" log &&
+	test_grep "fetch> server-option=bar" log &&
+	rm -f log &&
+
+	# Empty value of remote.<name>.serverOption clears the list
+	git -C myclone config --add remote.origin.serverOption "" &&
+	git -C myclone config --add remote.origin.serverOption tar &&
+	GIT_TRACE_PACKET="$(pwd)/log" git -C myclone -c protocol.version=2 \
+		fetch origin main &&
+	git -C myclone log -1 --format=%s origin/main >actual &&
+	test_cmp expect actual &&
+	test_grep "fetch> server-option=tar" log &&
+	test_grep ! "fetch> server-option=foo" log &&
+	test_grep ! "fetch> server-option=bar" log &&
+	rm -f log &&
+
+	# Server option from command line overrides those from configuration
+	GIT_TRACE_PACKET="$(pwd)/log" git -C myclone -c protocol.version=2 \
+		fetch -o hello -o world origin main &&
+	git -C myclone log -1 --format=%s origin/main >actual &&
+	test_cmp expect actual &&
+	test_grep "fetch> server-option=hello" log &&
+	test_grep "fetch> server-option=world" log &&
+	test_grep ! "fetch> server-option=tar" log
+'
+
 test_expect_success 'warn if using server-option with fetch with legacy protocol' '
 	test_when_finished "rm -rf temp_child" &&
 
@@ -404,6 +479,37 @@ test_expect_success 'server-options are sent when cloning' '
 	grep "server-option=world" log
 '
 
+test_expect_success 'server-options from configuration are used by git-clone' '
+	test_when_finished "rm -rf log myclone" &&
+
+	# Default server options from configuration are used
+	GIT_TRACE_PACKET="$(pwd)/log" git -c protocol.version=2 \
+		-c remote.origin.serverOption=foo -c remote.origin.serverOption=bar \
+		clone "file://$(pwd)/file_parent" myclone &&
+	test_grep "clone> server-option=foo" log &&
+	test_grep "clone> server-option=bar" log &&
+	rm -rf log myclone &&
+
+	# Empty value of remote.<name>.serverOption clears the list
+	GIT_TRACE_PACKET="$(pwd)/log" git -c protocol.version=2 \
+		-c remote.origin.serverOption=foo -c remote.origin.serverOption=bar \
+		-c remote.origin.serverOption= -c remote.origin.serverOption=tar \
+		clone "file://$(pwd)/file_parent" myclone &&
+	test_grep "clone> server-option=tar" log &&
+	test_grep ! "clone> server-option=foo" log &&
+	test_grep ! "clone> server-option=bar" log &&
+	rm -rf log myclone &&
+
+	# Server option from command line overrides those from configuration
+	GIT_TRACE_PACKET="$(pwd)/log" git -c protocol.version=2 \
+		-c remote.origin.serverOption=tar \
+		clone --server-option=hello --server-option=world \
+		"file://$(pwd)/file_parent" myclone &&
+	test_grep "clone> server-option=hello" log &&
+	test_grep "clone> server-option=world" log &&
+	test_grep ! "clone> server-option=tar" log
+'
+
 test_expect_success 'warn if using server-option with clone with legacy protocol' '
 	test_when_finished "rm -rf myclone" &&
 
@@ -415,6 +521,23 @@ test_expect_success 'warn if using server-option with clone with legacy protocol
 	test_grep "server options require protocol version 2 or later" err
 '
 
+test_expect_success 'server-option configuration with legacy protocol is ok' '
+	test_when_finished "rm -rf myclone" &&
+
+	env GIT_TEST_PROTOCOL_VERSION=0 git -c protocol.version=0 \
+		-c remote.origin.serverOption=foo -c remote.origin.serverOption=bar \
+		clone "file://$(pwd)/file_parent" myclone
+'
+
+test_expect_success 'invalid server-option configuration' '
+	test_when_finished "rm -rf myclone" &&
+
+	test_must_fail git -c protocol.version=2 \
+		-c remote.origin.serverOption \
+		clone "file://$(pwd)/file_parent" myclone 2>err &&
+	test_grep "error: missing value for '\''remote.origin.serveroption'\''" err
+'
+
 test_expect_success 'upload-pack respects config using protocol v2' '
 	git init server &&
 	write_script server/.git/hook <<-\EOF &&

transport.c

@@ -334,6 +334,9 @@ static struct ref *handshake(struct transport *transport, int for_push,
 	data->version = discover_version(&reader);
 	switch (data->version) {
 	case protocol_v2:
+		if ((!transport->server_options || !transport->server_options->nr) &&
+		    transport->remote->server_options.nr)
+			transport->server_options = &transport->remote->server_options;
 		if (server_feature_v2("session-id", &server_sid))
 			trace2_data_string("transfer", NULL, "server-sid", server_sid);
 		if (must_list_refs)