master e9e5d0ba73: Fix BadValue crash when looking up empty color names on some X servers

[Po Lu]

branch: master
commit e9e5d0ba7342f709080090857d9d37ea07a49c81
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix BadValue crash when looking up empty color names on some X servers
    
    * src/xterm.c (x_parse_color): Avoid parsing empty color names.
---
 src/xterm.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/xterm.c b/src/xterm.c
index 5adbf210be..a53f2982c6 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -2789,8 +2789,9 @@ x_query_frame_background_color (struct frame *f, XColor 
*bgcolor)
    and names we've actually looked up; list-colors-display is probably
    the most color-intensive case we're likely to hit.  */
 
-Status x_parse_color (struct frame *f, const char *color_name,
-                     XColor *color)
+Status
+x_parse_color (struct frame *f, const char *color_name,
+              XColor *color)
 {
   /* Don't pass #RGB strings directly to XParseColor, because that
      follows the X convention of zero-extending each channel
@@ -2819,6 +2820,10 @@ Status x_parse_color (struct frame *f, const char 
*color_name,
        }
     }
 
+  /* Some X servers send BadValue on empty color names.  */
+  if (!strlen (color_name))
+    return 0;
+
   if (XParseColor (dpy, cmap, color_name, color) == 0)
     /* No caching of negative results, currently.  */
     return 0;