+ /*
+ * We have to do a _lot_ of error checking here to be sure we can
+ * really use the XSHM extension. It seems different servers trigger
+ * errors at different points if the extension won't work. Therefore
+ * we have to be very careful...
+ */
+#if 0
+ GC gc;
+#endif
+ int (*old_handler)(XMesaDisplay *, XErrorEvent *);
+
+ b->tempImage = XShmCreateImage(xmb->xm_visual->display,
+ xmb->xm_visual->visinfo->visual,
+ xmb->xm_visual->visinfo->depth,
+ ZPixmap,
+ NULL,
+ &b->shminfo,
+ width, height);
+ if (b->tempImage == NULL) {
+ b->shm = 0;
+ return;
+ }
+
+
+ mesaXErrorFlag = 0;
+ old_handler = XSetErrorHandler(mesaHandleXError);
+ /* This may trigger the X protocol error we're ready to catch: */
+ XShmAttach(xmb->xm_visual->display, &b->shminfo);
+ XSync(xmb->xm_visual->display, False);
+
+ if (mesaXErrorFlag) {
+ /* we are on a remote display, this error is normal, don't print it */
+ XFlush(xmb->xm_visual->display);
+ mesaXErrorFlag = 0;
+ XDestroyImage(b->tempImage);
+ b->tempImage = NULL;
+ b->shm = 0;
+ (void) XSetErrorHandler(old_handler);
+ return;
+ }
+
+
+ /* Finally, try an XShmPutImage to be really sure the extension works */
+#if 0
+ gc = XCreateGC(xmb->xm_visual->display, xmb->drawable, 0, NULL);
+ XShmPutImage(xmb->xm_visual->display, xmb->drawable, gc,
+ b->tempImage, 0, 0, 0, 0, 1, 1 /*one pixel*/, False);
+ XSync(xmb->xm_visual->display, False);
+ XFreeGC(xmb->xm_visual->display, gc);
+ (void) XSetErrorHandler(old_handler);
+ if (mesaXErrorFlag) {
+ XFlush(xmb->xm_visual->display);
+ mesaXErrorFlag = 0;
+ XDestroyImage(b->tempImage);
+ b->tempImage = NULL;
+ b->shm = 0;
+ return;
+ }
+#endif
+}
+
+#else
+
+#define XSHM_ENABLED(b) 0
+
+static void
+alloc_shm_ximage(struct xm_buffer *b, struct xmesa_buffer *xmb,
+ unsigned width, unsigned height)
+{
+ b->shm = 0;