drisw: Try harder to probe whether MIT-SHM works

[mesa.git] / src / glx / drisw_glx.c

diff --git a/src/glx/drisw_glx.c b/src/glx/drisw_glx.c
index c63b097a71abe8cd9f85758967fe9a038fe10411..f38dbbca2dffee18ce327724774f9b62ba1ce65c 100644 (file)
--- a/src/glx/drisw_glx.c
+++ b/src/glx/drisw_glx.c
@@ -73,11 +73,10 @@ handle_xerror(Display *dpy, XErrorEvent *event)
    (void) dpy;
 
    assert(xshm_opcode != -1);
-   if (event->request_code != xshm_opcode ||
-       event->minor_code != X_ShmAttach)
+   if (event->request_code != xshm_opcode)
       return 0;
 
-   xshm_error = 1;
+   xshm_error = event->error_code;
    return 0;
 }
 
@@ -826,9 +825,27 @@ driswBindExtensions(struct drisw_screen *psc, const __DRIextension **extensions)
 static int
 check_xshm(Display *dpy)
 {
+   int (*old_handler)(Display *, XErrorEvent *);
+
    int ignore;
+   XShmSegmentInfo info = { 0, };
+
+   if (!XQueryExtension(dpy, "MIT-SHM", &xshm_opcode, &ignore, &ignore))
+      return False;
+
+   old_handler = XSetErrorHandler(handle_xerror);
+   XShmDetach(dpy, &info);
+   XSync(dpy, False);
+   (void) XSetErrorHandler(old_handler);
 
-   return XQueryExtension(dpy, "MIT-SHM", &xshm_opcode, &ignore, &ignore);
+   /* BadRequest means we're a remote client. If we were local we'd
+    * expect BadValue since 'info' has an invalid segment name.
+    */
+   if (xshm_error == BadRequest)
+      return False;
+
+   xshm_error = 0;
+   return True;
 }
 
 static struct glx_screen *