2 files changed, 25 insertions, 1 deletions

diff --git a/sway/commands/font.c b/sway/commands/font.c
index 3eda0a9c..74bb6b9f 100644
--- a/sway/commands/font.c
+++ b/sway/commands/font.c
@@ -4,6 +4,7 @@
 #include "sway/config.h"
 #include "log.h"
 #include "stringop.h"
+#include <pango/pangocairo.h>
 
 struct cmd_results *cmd_font(int argc, char **argv) {
         struct cmd_results *error = NULL;
@@ -22,6 +23,28 @@ struct cmd_results *cmd_font(int argc, char **argv) {
                 config->font = font;
         }
 
+        // Parse the font early so we can reject it if it's not valid for pango.
+        // Also avoids re-parsing each time we render text.
+        PangoFontDescription *font_description = pango_font_description_from_string(config->font);
+
+        const char *family = pango_font_description_get_family(font_description);
+        if (family == NULL) {
+                pango_font_description_free(font_description);
+                return cmd_results_new(CMD_FAILURE, "Invalid font family.");
+        }
+
+        const gint size = pango_font_description_get_size(font_description);
+        if (size == 0) {
+                pango_font_description_free(font_description);
+                return cmd_results_new(CMD_FAILURE, "Invalid font size.");
+        }
+
+        if (config->font_description != NULL) {
+                pango_font_description_free(config->font_description);
+        }
+
+        config->font_description = font_description;
         config_update_font_height();
+
         return cmd_results_new(CMD_SUCCESS, NULL);
 }
diff --git a/sway/config.c b/sway/config.c
index 8220ece0..b41dd871 100644
--- a/sway/config.c
+++ b/sway/config.c
@@ -243,6 +243,7 @@ static void config_defaults(struct sway_config *config) {
         config->default_layout = L_NONE;
         config->default_orientation = L_NONE;
         if (!(config->font = strdup("monospace 10"))) goto cleanup;
+        config->font_description = pango_font_description_from_string(config->font);
         config->urgent_timeout = 500;
         config->focus_on_window_activation = FOWA_URGENT;
         config->popup_during_fullscreen = POPUP_SMART;
@@ -1006,7 +1007,7 @@ int workspace_output_cmp_workspace(const void *a, const void *b) {
 void config_update_font_height(void) {
         int prev_max_height = config->font_height;
 
-        get_text_metrics(config->font, &config->font_height, &config->font_baseline);
+        get_text_metrics(config->font_description, &config->font_height, &config->font_baseline);
 
         if (config->font_height != prev_max_height) {
                 arrange_root();