Attachment 143766 Details for Bug 99781 – A single-threaded reproducer

A single-threaded reproducer

own_reproducer.c (text/plain), 2.62 KB, created by Uli Schlachter on 2019-03-24 16:41:44 UTC

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Creator: Uli Schlachter

Created: 2019-03-24 16:41:44 UTC

Size: 2.62 KB

patch

obsolete

>#include <X11/Xlib.h>
>#include <X11/Xproto.h>
>#include <X11/Xlibint.h>
>#include <X11/Xlib-xcb.h>
>#include <stdio.h>
>#include <assert.h>
>
>static int handler(Display *dpy, XErrorEvent *err)
>{
>	(void) dpy, (void) err;
>	puts("in error handler");
>	return 0;
>}
>
>static void __glXSendError(Display * dpy, int errorCode, int resourceID, int minorCode)
>{
>   xError error;
>
>   XLockDisplay(dpy);
>
>   error.type = X_Error;
>
>      error.errorCode = errorCode;
>
>   error.sequenceNumber = dpy->request;
>   error.resourceID = resourceID;
>   error.minorCode = minorCode;
>   error.majorCode = minorCode;
>
>   _XError(dpy, &error);
>
>   XUnlockDisplay(dpy);
>}
>
>static void sync_xcb(xcb_connection_t *c)
>{
>	xcb_get_input_focus_reply(c, xcb_get_input_focus(c), NULL);
>}
>
>int main()
>{
>	Window own;
>	Display *dpy = XOpenDisplay(NULL);
>	xcb_connection_t *c = XGetXCBConnection(dpy);
>	XSetErrorHandler(handler);
>
>	/* Sequence 7: CreateWindow */
>	own = xcb_generate_id(c);
>	xcb_create_window(c, 24, own, RootWindow(dpy, 0), 0, 0, 10, 10, 0, XCB_COPY_FROM_PARENT, XCB_COPY_FROM_PARENT,
>			XCB_CW_EVENT_MASK, (uint32_t[]) { XCB_EVENT_MASK_KEY_PRESS });
>
>	XKeyEvent event;
>	event.type=KeyPress;
>	event.keycode=42;
>	event.display=dpy;
>	event.root=own;
>
>	/* Sequence 8: Send us an event */
>	XSendEvent(dpy,own,True,KeyPressMask,(XEvent *)&event);
>
>	/* To avoid a race with the X11 server: Make sure the event we
>	 * just sent was already received by xcb (but not yet Xlib)
>	 * Sequence 9
>	 */
>	sync_xcb(c);
>
>	/* Send us another event */
>	/* Sequence 10: */
>	XSendEvent(dpy,own,True,KeyPressMask,(XEvent *)&event);
>	assert(dpy->request == 10 && XNextRequest(dpy) == 11);
>	assert(dpy->last_request_read == 8);
>
>	/* Increase dpy->request some more */
>	/* Sequence 11: */
>	XNoOp(dpy);
>	assert(dpy->request == 11 && XNextRequest(dpy) == 12);
>
>	/* To avoid a race with the X11 server: Make sure the event we
>	 * just sent was already received by xcb (but not yet Xlib)
>	 * Sequence 12:
>	 */
>	sync_xcb(c);
>	assert(dpy->request == 11);
>	assert(dpy->last_request_read == 8);
>
>	/* Set last_request_read into the future (incorrectly) */
>
>	__glXSendError(dpy, 42, 42, 42);
>	assert(dpy->request == 11);
>	assert(dpy->last_request_read == 11);
>
>	/* XLib will now read the event we generated above (sequence number 10).
>	 * Thanks to XNoOp(), dpy->request was already 11. The call to _XError()
>	 * thus caused request_read to be 11. Since 10 is less than 11, widen()
>	 * assumes an overflow and adds 1 << 32 to the sequence.
>	 *
>	 * Something else that I just got right by trial and error makes sure
>	 * that dpy->xcb->pending_requests is NULL.
>	 */
>	XEvent xevent;
>	XNextEvent(dpy, &xevent);
>
>	XCloseDisplay(dpy);
>	return 0;
>}

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Attachments on bug 99781: 143763 | 143764 | 143765 | 143766 | 143767 | 144685

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