libXinerama: Set number of screens to 0 on error

The documentation of XineramaQueryScreens states that number is always
set to the amount of screens in the returned array, but if the
communication with the X server fails, NULL is returned without
modifying number.

At least dwm relies on the fact that number is set to 0 on error, i.e.
when NULL is returned. As a NULL pointer contains 0 elements and the
documentation states that number contains the amount of elements of the
returned array, I think this should be fixed inside libXinerama.

Reviewed-by: Adam Jackson <ajax@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/Xinerama.c b/src/Xinerama.c
index 8472ec5..ee1f630 100644
--- a/src/Xinerama.c
+++ b/src/Xinerama.c
@@ -286,6 +286,7 @@ XineramaQueryScreens(
     if (!_XReply (dpy, (xReply *) &rep, 0, xFalse)) {
 	UnlockDisplay (dpy);
 	SyncHandle ();
+	*number = 0;
 	return NULL;
     }