window-rules: support title criteria

Example config:

    <windowRules>
      <windowRule identifier="foot" title="max">
        <action name="Maximize"/>
      </windowRule>
    </windowRules>

Observe that:

- `foot -T foo` starts maximized
- `xterm -T foo` starts normal

src/config/rcxml.c

@@ -88,9 +88,16 @@ fill_window_rule(char *nodename, char *content)
 		/* nop */
 	} else if (!current_window_rule) {
 		wlr_log(WLR_ERROR, "no window-rule");
+
+	/* Criteria */
 	} else if (!strcmp(nodename, "identifier")) {
 		free(current_window_rule->identifier);
 		current_window_rule->identifier = xstrdup(content);
+	} else if (!strcmp(nodename, "title")) {
+		free(current_window_rule->title);
+		current_window_rule->title = xstrdup(content);
+
+	/* Event */
 	} else if (!strcmp(nodename, "event")) {
 		/*
 		 * This is just in readiness for adding any other types of
@@ -99,8 +106,12 @@ fill_window_rule(char *nodename, char *content)
 		if (!strcasecmp(content, "onFirstMap")) {
 			current_window_rule->event = LAB_WINDOW_RULE_EVENT_ON_FIRST_MAP;
 		}
+
+	/* Properties */
 	} else if (!strcasecmp(nodename, "serverDecoration")) {
 		set_property(content, &current_window_rule->server_decoration);
+
+	/* Actions */
 	} else if (!strcmp(nodename, "name.action")) {
 		current_window_rule_action = action_create(content);
 		if (current_window_rule_action) {
@@ -1027,6 +1038,29 @@ post_processing(void)
 	}
 }
 
+static void
+rule_destroy(struct window_rule *rule)
+{
+	wl_list_remove(&rule->link);
+	zfree(rule->identifier);
+	zfree(rule->title);
+	action_list_free(&rule->actions);
+	zfree(rule);
+}
+
+static void
+validate(void)
+{
+	/* Window-rule criteria */
+	struct window_rule *rule, *next;
+	wl_list_for_each_safe(rule, next, &rc.window_rules, link) {
+		if (!rule->identifier && !rule->title) {
+			wlr_log(WLR_ERROR, "deleting rule %p as no criteria", rule);
+			rule_destroy(rule);
+		}
+	}
+}
+
 static void
 rcxml_path(char *buf, size_t len)
 {
@@ -1091,6 +1125,7 @@ rcxml_read(const char *filename)
 	free(b.buf);
 no_config:
 	post_processing();
+	validate();
 }
 
 void
@@ -1140,10 +1175,7 @@ rcxml_finish(void)
 
 	struct window_rule *rule, *rule_tmp;
 	wl_list_for_each_safe(rule, rule_tmp, &rc.window_rules, link) {
-		wl_list_remove(&rule->link);
-		zfree(rule->identifier);
-		action_list_free(&rule->actions);
-		zfree(rule);
+		rule_destroy(rule);
 	}
 
 	/* Reset state vars for starting fresh when Reload is triggered */

src/window-rules.c

@@ -2,6 +2,7 @@
 #define _POSIX_C_SOURCE 200809L
 #include "config.h"
 #include <assert.h>
+#include <stdbool.h>
 #include <cairo.h>
 #include <glib.h>
 #include <strings.h>
@@ -13,20 +14,44 @@
 #include "view.h"
 #include "window-rules.h"
 
+/* Try to match against identifier AND title (if set) */
+static bool
+view_matches_criteria(struct window_rule *rule, struct view *view)
+{
+	const char *id = view_get_string_prop(view, "app_id");
+	const char *title = view_get_string_prop(view, "title");
+
+	if (rule->identifier && rule->title) {
+		if (!id || !title) {
+			return false;
+		}
+		return match_glob(rule->identifier, id)
+			&& match_glob(rule->title, title);
+	} else if (rule->identifier) {
+		if (!id) {
+			return false;
+		}
+		return match_glob(rule->identifier, id);
+	} else if (rule->title) {
+		if (!title) {
+			return false;
+		}
+		return match_glob(rule->title, title);
+	} else {
+		wlr_log(WLR_ERROR, "rule has no identifier or title\n");
+		return false;
+	}
+}
+
 void
 window_rules_apply(struct view *view, enum window_rule_event event)
 {
-	const char *identifier = view_get_string_prop(view, "app_id");
-	if (!identifier) {
-		return;
-	}
-
 	struct window_rule *rule;
 	wl_list_for_each(rule, &rc.window_rules, link) {
-		if (!rule->identifier || rule->event != event) {
+		if (rule->event != event) {
 			continue;
 		}
-		if (match_glob(rule->identifier, identifier)) {
+		if (view_matches_criteria(rule, view)) {
 			actions_run(view, view->server, &rule->actions, 0);
 		}
 	}
@@ -37,11 +62,6 @@ window_rules_get_property(struct view *view, const char *property)
 {
 	assert(property);
 
-	const char *identifier = view_get_string_prop(view, "app_id");
-	if (!identifier) {
-		goto out;
-	}
-
 	/*
 	 * We iterate in reverse here because later items in list have higher
 	 * priority. For example, in the config below we want the return value
@@ -54,16 +74,13 @@ window_rules_get_property(struct view *view, const char *property)
 	 */
 	struct window_rule *rule;
 	wl_list_for_each_reverse(rule, &rc.window_rules, link) {
-		if (!rule->identifier) {
-			continue;
-		}
 		/*
 		 * Only return if property != LAB_PROP_UNSPECIFIED otherwise a
 		 * <windowRule> which does not set a particular property
 		 * attribute would still return here if that property was asked
 		 * for.
 		 */
-		if (match_glob(rule->identifier, identifier)) {
+		if (view_matches_criteria(rule, view)) {
 			if (!strcasecmp(property, "serverDecoration")) {
 				if (rule->server_decoration) {
 					return rule->server_decoration;
@@ -71,6 +88,5 @@ window_rules_get_property(struct view *view, const char *property)
 			}
 		}
 	}
-out:
 	return LAB_PROP_UNSPECIFIED;
 }