[gimp] app: check that the font path is not NULL.

[Jehan Pagès <jehanp src gnome org>]

commit 55d1ea5cf05a3acb22890cd63dca446dd8e9f8d9
Author: Jehan <jehan girinstud io>
Date:   Mon Apr 30 22:02:31 2018 +0200

    app: check that the font path is not NULL.
    
    This is for Windows where we apparently need to call
    g_win32_locale_filename_from_utf8() before feeding the path to
    FcConfigAppFontAddFile().
    Unfortunately as we discovered earlier (cf. commit ba06a0fe86), this
    can sometimes return NULL. So we absolutely need to check for the path
    not being NULL first.

 app/text/gimp-fonts.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/app/text/gimp-fonts.c b/app/text/gimp-fonts.c
index 3660602..d708d87 100644
--- a/app/text/gimp-fonts.c
+++ b/app/text/gimp-fonts.c
@@ -307,10 +307,15 @@ gimp_fonts_recursive_add_fontdir (FcConfig  *config,
               gchar *tmp = g_win32_locale_filename_from_utf8 (path);
 
               g_free (path);
+              /* XXX: g_win32_locale_filename_from_utf8() may return
+               * NULL. So we need to check that path is not NULL before
+               * trying to load with fontconfig.
+               */
               path = tmp;
 #endif
 
-              if (FcFalse == FcConfigAppFontAddFile (config, (const FcChar8 *) path))
+              if (! path ||
+                  FcFalse == FcConfigAppFontAddFile (config, (const FcChar8 *) path))
                 {
                   g_printerr ("%s: adding font file '%s' failed.\n",
                               G_STRFUNC, path);