dix: Return BadWindow rather than BadMatch from dixLookupWindow

dixLookupWindow uses dixLookupDrawable internally, which returns
BadMatch when the XID matches a non-Window drawable.  Users
of dixLookupWindow don't care about this, just that it's not
a valid Window.

This is a generalised version of the fix for X.Org Bug 23562,
where GetProperty was incorrectly returning BadMatch. Auditing other
window requests, all that I checked would incorrectly return BadMatch
in these circumstances.  An incomplete list of calls that could
incorrectly return BadMatch is: ListProperties, SetSelectionOwner,
{Destroy,Map,Unmap}{,Sub}Window.

None of the callers of dixLookupWindow, except for GetProperty, check
for BadMatch

Signed-off-by: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/dix/dixutils.c b/dix/dixutils.c
index 2b5391f2d..da26dc144 100644
--- a/dix/dixutils.c
+++ b/dix/dixutils.c
@@ -224,7 +224,15 @@ dixLookupWindow(WindowPtr *pWin, XID id, ClientPtr client, Mask access)
 {
     int rc;
     rc = dixLookupDrawable((DrawablePtr*)pWin, id, client, M_WINDOW, access);
-    return (rc == BadDrawable) ? BadWindow : rc;
+    /* dixLookupDrawable returns BadMatch iff id is a valid Drawable
+       but is not a Window. Users of dixLookupWindow expect a BadWindow
+       error in this case; they don't care that it's a valid non-Window XID */
+    if (rc == BadMatch)
+	rc = BadWindow;
+    /* Similarly, users of dixLookupWindow don't want BadDrawable. */
+    if (rc == BadDrawable)
+	rc = BadWindow;
+    return rc;
 }
 
 int