1 files changed, 26 insertions, 4 deletions

diff --git a/sway/commands/font.c b/sway/commands/font.c
index c54365b5..9920d03e 100644
--- a/sway/commands/font.c
+++ b/sway/commands/font.c
@@ -1,9 +1,9 @@
-#define _POSIX_C_SOURCE 200809L
 #include <string.h>
 #include "sway/commands.h"
 #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;
@@ -16,12 +16,34 @@ struct cmd_results *cmd_font(int argc, char **argv) {
         if (strncmp(font, "pango:", 6) == 0) {
                 config->pango_markup = true;
                 config->font = strdup(font + 6);
+                free(font);
         } else {
                 config->pango_markup = false;
-                config->font = strdup(font);
+                config->font = font;
         }
 
-        free(font);
-        config_update_font_height(true);
+        // 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);
 }