On OSX, do not free font-specific data more than once (Bug#18501).

* macfont.m (macfont_close): Release and free font-specific data
only if it wasn't previously freed.

src/ChangeLog

+2014-09-22  Dmitry Antipov  <dmantipov@yandex.ru>
+
+	On OSX, do not free font-specific data more than once (Bug#18501).
+	* macfont.m (macfont_close): Release and free font-specific data
+	only if it wasn't previously freed.
+
 2014-09-21  David Caldwell <david@porkrind.org> (tiny change)
 
 	* unexmacosx.c (dump_it): Improve error message.

src/macfont.m

@@ -2616,20 +2616,25 @@ So we use CTFontDescriptorCreateMatchingFontDescriptor (no
 macfont_close (struct font *font)
 {
   struct macfont_info *macfont_info = (struct macfont_info *) font;
-  int i;
 
-  block_input ();
-  CFRelease (macfont_info->macfont);
-  CGFontRelease (macfont_info->cgfont);
-  if (macfont_info->screen_font)
-    CFRelease (macfont_info->screen_font);
-  macfont_release_cache (macfont_info->cache);
-  for (i = 0; i < macfont_info->metrics_nrows; i++)
-    if (macfont_info->metrics[i])
-      xfree (macfont_info->metrics[i]);
-  if (macfont_info->metrics)
-    xfree (macfont_info->metrics);
-  unblock_input ();
+  if (macfont_info->cache)
+    {
+      int i;
+
+      block_input ();
+      CFRelease (macfont_info->macfont);
+      CGFontRelease (macfont_info->cgfont);
+      if (macfont_info->screen_font)
+	CFRelease (macfont_info->screen_font);
+      macfont_release_cache (macfont_info->cache);
+      for (i = 0; i < macfont_info->metrics_nrows; i++)
+	if (macfont_info->metrics[i])
+	  xfree (macfont_info->metrics[i]);
+      if (macfont_info->metrics)
+	xfree (macfont_info->metrics);
+      macfont_info->cache = NULL;
+      unblock_input ();
+    }
 }
 
 static int