Don't apply fonts that don't result in family name or have size 0.

Issue: 554

include/helper.h

@@ -234,4 +234,12 @@ int rofi_scorer_fuzzy_evaluate ( const char *pattern, glong plen, const char *st
  *          characters (not bytes) of `b`.
  */
 int utf8_strncmp ( const char *a, const char* b, size_t n );
+
+/**
+ * @param pfd Pango font description to validate.
+ * @param font The name of the font to check.
+ *
+ * @returns true if font is valid.
+ */
+gboolean helper_validate_font ( PangoFontDescription *pfd, const char *font );
 #endif // ROFI_HELPER_H

source/helper.c

@@ -50,6 +50,8 @@
 #include "rofi.h"
 #include "view.h"
 
+#define LOG_DOMAIN "Helper"
+
 const char *const monitor_position_entries[] = {
     "on focused monitor",
     "on focused window",
@@ -524,6 +526,18 @@ void remove_pid_file ( int fd )
     }
 }
 
+gboolean helper_validate_font ( PangoFontDescription *pfd, const char *font )
+{
+    const char           *fam = pango_font_description_get_family ( pfd );
+    int                  size = pango_font_description_get_size ( pfd );
+    if ( fam == NULL || size == 0 ){
+        g_log ( LOG_DOMAIN, G_LOG_LEVEL_DEBUG, "Pango failed to parse font: '%s'", font);
+        g_log ( LOG_DOMAIN, G_LOG_LEVEL_DEBUG, "Got family: <b>%s</b> at size: <b>%d</b>", fam?fam:"{unknown}", size);
+        return FALSE;
+    }
+    return TRUE;
+}
+
 /**
  * Do some input validation, especially the first few could break things.
  * It is good to catch them beforehand.

source/view.c

@@ -694,7 +694,9 @@ void __create_window ( MenuFlags menu_flags )
     char      *font = rofi_theme_get_string ( WIDGET ( win ), "font", config.menu_font );
     if ( font ) {
         PangoFontDescription *pfd = pango_font_description_from_string ( font );
-        pango_context_set_font_description ( p, pfd );
+        if ( helper_validate_font(pfd, font)) {
+            pango_context_set_font_description ( p, pfd );
+        }
         pango_font_description_free ( pfd );
     }
     PangoLanguage *l = pango_language_get_default();

source/widgets/textbox.c

@@ -31,6 +31,7 @@
 #include <math.h>
 #include "widgets/textbox.h"
 #include "keyb.h"
+#include "helper.h"
 #include "x11-helper.h"
 #include "mode.h"
 #include "view.h"
@@ -125,12 +126,20 @@ textbox* textbox_create ( const char *name, TextboxFlags flags, TextBoxFontType
         if ( tbfc == NULL ){
             tbfc = g_malloc0 ( sizeof (TBFontConfig) );
             tbfc->pfd = pango_font_description_from_string ( font );
-            tbfc->metrics = pango_context_get_metrics ( p_context, tbfc->pfd, NULL );
-            g_hash_table_insert ( tbfc_cache, font, tbfc);
+            if ( helper_validate_font ( tbfc->pfd, font)) {
+                tbfc->metrics = pango_context_get_metrics ( p_context, tbfc->pfd, NULL );
+                g_hash_table_insert ( tbfc_cache, font, tbfc);
+            } else {
+                pango_font_description_free ( tbfc->pfd );
+                g_free( tbfc);
+                tbfc = NULL;
+            }
+        }
+        if ( tbfc ) {
+            // Update for used font.
+            pango_layout_set_font_description ( tb->layout, tbfc->pfd );
+            tb->metrics = tbfc->metrics;
         }
-        // Update for used font.
-        pango_layout_set_font_description ( tb->layout, tbfc->pfd );
-        tb->metrics = tbfc->metrics;
     }