From fc353003f93883bf62a9865472e6f206a62b09f1 Mon Sep 17 00:00:00 2001
From: Mamoru TASAKA <mtasaka@fedoraproject.org>
Date: Thu, 8 Jul 2021 23:06:46 +0900
Subject: [PATCH] window_init: check if asterisk font is available and provide
 fallback character

Downstream bug: https://bugzilla.redhat.com/show_bug.cgi?id=1980173
On Fedora 34, using US locale (LANG=en_US.UTF-8), when both
"dejavu-sans-fonts" and "bitstream-vera-sans-fonts" rpms are installed,
* xscreensaver-auth requests "sans-serif" to xft
* xft chooses bitstream-vera-sans (according to fontconfig settings)
  45-latin.conf seems to be saying so.
* gucharmap shows that while "dejavu-sans-fonts" contains glyph for "U+25CF",
  however bitstream-vera-sans-fonts does not.
Then such people sees white rectangles when typing password.

For now, check if corresponding font is available, and if not, provide
fallback character
---
 driver/dialog.c | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/driver/dialog.c b/driver/dialog.c
index 7f1ec8b..a17e9af 100644
--- a/driver/dialog.c
+++ b/driver/dialog.c
@@ -79,6 +79,7 @@
 #include "font-retry.h"
 #include "prefs.h"
 #include "usleep.h"
+#include "utf8wc.h"
 
 extern Bool debug_p;
 
@@ -193,6 +194,7 @@ struct window_state {
   char *date_format;
   char *kbd_layout_label;
   char *newlogin_cmd;
+  const char *asterisk_utf8;
 
   /* Resources for fonts and colors */
   XftDraw *xftdraw;
@@ -674,6 +676,31 @@ get_int (window_state *ws, const char *name, const char *rclass)
   return get_integer_resource (ws->dpy, (char *) name, (char *) rclass);
 }
 
+static const char *pickup_asterisk_utf8 (window_state *ws)
+{
+    static char picked_string[8];
+    const unsigned long uc_list[] = {
+        0x25CF, /* Black Circle */
+        0x2022, /* Bullet */
+        '*'     /* Fallback */
+    };
+    const unsigned long *uc_cand = uc_list;
+    int encoded_length;
+    size_t index;
+
+    /* -1 is so that result will pick up fallback string as a last resort */
+    for (index = 0; index < sizeof uc_list / sizeof *uc_list - 1; index++) {
+        /* borrowed from blank_character_p in texfont.c */
+        if (XftCharExists (ws->dpy, ws->label_font, (FcChar32) *uc_cand)) break;
+        uc_cand++;
+    }
+
+    encoded_length = utf8_encode(*uc_cand, picked_string, sizeof picked_string - 1);
+    picked_string[encoded_length] = 0;
+
+    return picked_string;
+}
+
 
 /* Decide where on the X11 screen to place the dialog.
    This is complicated because, in the face of RANDR and Xinerama, we want
@@ -983,6 +1010,8 @@ window_init (Widget root_widget, Bool splash_p)
   ws->label_font    = get_font (ws, "labelFont");
   ws->date_font     = get_font (ws, "dateFont");
   ws->hostname_font = get_font (ws, "unameFont");
+
+  ws->asterisk_utf8 = pickup_asterisk_utf8(ws);
   
   ws->foreground = get_color (ws, "foreground", "Foreground");
   ws->background = get_color (ws, "background", "Background");
@@ -2003,9 +2032,7 @@ handle_keypress (window_state *ws, XKeyEvent *event)
     *out = 0;
     for (i = 0; i < MAX_PASSWD_CHARS && ws->plaintext_passwd_char_size[i]; i++)
       {
-        const char *b = /* "\xE2\x80\xA2"; */	/* U+2022 Bullet */
-			   "\xe2\x97\x8f";	/* U+25CF Black Circle */
-        strcat (out, b);
+        strcat (out, ws->asterisk_utf8);
         out += strlen(out);
       }
   }
-- 
2.31.1