remote: add remote.*.negotiationRestrict config

In a previous change, the --negotiation-restrict command-line option of
'git fetch' was added as a synonym of --negotiation-tips. Both of these
options restrict the set of 'haves' the client can send as part of
negotiation.

This was previously not available via a configuration option. Add a new
'remote.<name>.negotiationRestrict' multi-valued config option that
updates 'git fetch <name>' to use these restrictions by default.

If the user provides even one --negotiation-restrict argument, then the
config is ignored.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: derrickstolee

Documentation/config/remote.adoc

@@ -107,6 +107,22 @@ priority configuration file (e.g. `.git/config` in a repository) to clear
 the values inherited from a lower priority configuration files (e.g.
 `$HOME/.gitconfig`).
 
+remote.<name>.negotiationRestrict::
+	When negotiating with this remote during `git fetch` and `git push`,
+	restrict the commits advertised as "have" lines to only those
+	reachable from refs matching the given patterns.  This multi-valued
+	config option behaves like `--negotiation-restrict` on the command
+	line.
++
+Each value is either an exact ref name (e.g. `refs/heads/release`) or a
+glob pattern (e.g. `refs/heads/release/*`).  The pattern syntax is the
+same as for `--negotiation-restrict`.
++
+These config values are used as defaults for the `--negotiation-restrict`
+command-line option.  If `--negotiation-restrict` (or its synonym
+`--negotiation-tip`) is specified on the command line, then the config
+values are not used.
+
 remote.<name>.followRemoteHEAD::
 	How linkgit:git-fetch[1] should handle updates to `remotes/<name>/HEAD`
 	when fetching using the configured refspecs of a remote.

builtin/fetch.c

@@ -1601,6 +1601,19 @@ static struct transport *prepare_transport(struct remote *remote, int deepen,
 		else
 			warning(_("ignoring %s because the protocol does not support it"),
 				"--negotiation-restrict");
+	} else if (remote->negotiation_restrict.nr) {
+		struct string_list_item *item;
+		for_each_string_list_item(item, &remote->negotiation_restrict)
+			string_list_append(&negotiation_tip, item->string);
+		if (transport->smart_options)
+			add_negotiation_restrict_tips(transport->smart_options);
+		else {
+			struct strbuf config_name = STRBUF_INIT;
+			strbuf_addf(&config_name, "remote.%s.negotiationRestrict", remote->name);
+			warning(_("ignoring %s because the protocol does not support it"),
+				config_name.buf);
+			strbuf_release(&config_name);
+		}
 	}
 	return transport;
 }
@@ -2659,8 +2672,12 @@ int cmd_fetch(int argc,
 		config.display_format = DISPLAY_FORMAT_PORCELAIN;
 	}
 
-	if (negotiate_only && !negotiation_tip.nr)
-		die(_("--negotiate-only needs one or more --negotiation-restrict=*"));
+	if (negotiate_only && !negotiation_tip.nr) {
+		/*
+		 * Defer this check: remote.<name>.negotiationRestrict may
+		 * provide defaults in prepare_transport().
+		 */
+	}
 
 	if (deepen_relative) {
 		if (deepen_relative < 0)
@@ -2749,6 +2766,9 @@ int cmd_fetch(int argc,
 		if (!remote)
 			die(_("must supply remote when using --negotiate-only"));
 		gtransport = prepare_transport(remote, 1, &filter_options);
+		if (!gtransport->smart_options ||
+		    !gtransport->smart_options->negotiation_restrict_tips)
+			die(_("--negotiate-only needs one or more --negotiation-restrict=*"));
 		if (gtransport->smart_options) {
 			gtransport->smart_options->acked_commits = &acked_commits;
 		} else {

remote.c

@@ -152,6 +152,7 @@ static struct remote *make_remote(struct remote_state *remote_state,
 	refspec_init_push(&ret->push);
 	refspec_init_fetch(&ret->fetch);
 	string_list_init_dup(&ret->server_options);
+	string_list_init_dup(&ret->negotiation_restrict);
 
 	ALLOC_GROW(remote_state->remotes, remote_state->remotes_nr + 1,
 		   remote_state->remotes_alloc);
@@ -179,6 +180,7 @@ static void remote_clear(struct remote *remote)
 	FREE_AND_NULL(remote->http_proxy);
 	FREE_AND_NULL(remote->http_proxy_authmethod);
 	string_list_clear(&remote->server_options, 0);
+	string_list_clear(&remote->negotiation_restrict, 0);
 }
 
 static void add_merge(struct branch *branch, const char *name)
@@ -562,6 +564,10 @@ static int handle_config(const char *key, const char *value,
 	} else if (!strcmp(subkey, "serveroption")) {
 		return parse_transport_option(key, value,
 					      &remote->server_options);
+	} else if (!strcmp(subkey, "negotiationrestrict")) {
+		if (!value)
+			return config_error_nonbool(key);
+		string_list_append(&remote->negotiation_restrict, value);
 	} else if (!strcmp(subkey, "followremotehead")) {
 		const char *no_warn_branch;
 		if (!strcmp(value, "never"))

remote.h

@@ -117,6 +117,7 @@ struct remote {
 	char *http_proxy_authmethod;
 
 	struct string_list server_options;
+	struct string_list negotiation_restrict;
 
 	enum follow_remote_head_settings follow_remote_head;
 	const char *no_warn_branch;

t/t5510-fetch.sh

@@ -1485,6 +1485,28 @@ test_expect_success '--negotiation-restrict and --negotiation-tip can be mixed'
 	check_negotiation_tip
 '
 
+test_expect_success 'remote.<name>.negotiationRestrict used as default' '
+	setup_negotiation_tip server server 0 &&
+	git -C client config --add remote.origin.negotiationRestrict alpha_1 &&
+	git -C client config --add remote.origin.negotiationRestrict beta_1 &&
+	GIT_TRACE_PACKET="$(pwd)/trace" git -C client fetch \
+		origin alpha_s beta_s &&
+	check_negotiation_tip
+'
+
+test_expect_success 'CLI --negotiation-restrict overrides remote config' '
+	setup_negotiation_tip server server 0 &&
+	git -C client config --add remote.origin.negotiationRestrict alpha_1 &&
+	git -C client config --add remote.origin.negotiationRestrict beta_1 &&
+	ALPHA_1=$(git -C client rev-parse alpha_1) &&
+	GIT_TRACE_PACKET="$(pwd)/trace" git -C client fetch \
+		--negotiation-restrict=alpha_1 \
+		origin alpha_s beta_s &&
+	test_grep "fetch> have $ALPHA_1" trace &&
+	BETA_1=$(git -C client rev-parse beta_1) &&
+	test_grep ! "fetch> have $BETA_1" trace
+'
+
 test_expect_success SYMLINKS 'clone does not get confused by a D/F conflict' '
 	git init df-conflict &&
 	(