[PATCH twm] Fix SEGV if CreateColormapWindow() returns NULL.

[Egbert Eich]

twm can segfault when it cannot collect attribute information on
a window that has been destroyed before it got a chance to collect
it's attributes.
twm seems to assume that it is always able to collect this information
and disregards the error if the function that attempts to collect it
fails and CreateColormapWindow() returns NULL.
If this happens correct number_cmap_windows to prevent a SEGV later
on due to an incorrect setting.

Signed-off-by: Egbert Eich <eich at freedesktop.org>
---
 src/add_window.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/add_window.c b/src/add_window.c
index 8cf23c5..72aa0aa 100644
--- a/src/add_window.c
+++ b/src/add_window.c
@@ -1535,10 +1535,12 @@ FetchWmColormapWindows (TwmWindow *tmp)
 
 	cwins = (ColormapWindow **) malloc(sizeof(ColormapWindow *));
 	if (XFindContext(dpy, tmp->w, ColormapContext, (caddr_t *)&cwins[0]) ==
-		XCNOENT)
+	    XCNOENT) {
 	    cwins[0] = CreateColormapWindow(tmp->w,
 			    (Bool) tmp->cmaps.number_cwins == 0, False);
-	else
+	    if (cwins[0] == NULL)
+		number_cmap_windows = 0;
+	} else
 	    cwins[0]->refcnt++;
     }
 
-- 
1.7.7