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xlib/shm: Sanity check that the server handles XSendEvent with ShmCompletion

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Uli Schlachter suggested it would be wiser to complement our blacklist
of known broken X/libXext with an explicit roundtrip to check for a
BadValue error return when we try to use XSendEvent.

Suggested-by: Uli Schlachter <psychon@znc.in>
Reported-by: Martin Husemann <martin@duskware.de>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
This commit is contained in:
Chris Wilson 2012-10-26 10:51:31 +01:00
parent e43f53bf7f
commit 00feb8ce53
1 changed files with 69 additions and 8 deletions
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77
src/cairo-xlib-surface-shm.c
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@ -1128,8 +1128,60 @@ _cairo_xlib_shm_surface_is_idle (cairo_surface_t *surface)
(((major) * 10000000) + ((minor) * 100000) + ((patch) * 1000) + snap)
static cairo_bool_t
xorg_has_buggy_send_shm_completion_event(Display *dpy)
has_broken_send_shm_event (cairo_xlib_display_t *display,
cairo_xlib_shm_display_t *shm)
{
Display *dpy = display->display;
int (*old_handler) (Display *display, XErrorEvent *event);
XShmCompletionEvent ev;
XShmSegmentInfo info;
info.shmid = shmget (IPC_PRIVATE, 0x1000, IPC_CREAT | 0600);
if (info.shmid == -1)
return TRUE;
info.readOnly = FALSE;
info.shmaddr = shmat (info.shmid, NULL, 0);
if (info.shmaddr == (char *) -1) {
shmctl (info.shmid, IPC_RMID, NULL);
return TRUE;
}
ev.type = shm->event;
ev.drawable = shm->window;
ev.major_code = shm->opcode;
ev.minor_code = X_ShmPutImage;
ev.shmseg = info.shmid;
ev.offset = 0;
assert (CAIRO_MUTEX_IS_LOCKED (_cairo_xlib_display_mutex));
_x_error_occurred = FALSE;
XLockDisplay (dpy);
XSync (dpy, False);
old_handler = XSetErrorHandler (_check_error_handler);
XShmAttach (dpy, &info);
XSendEvent (dpy, ev.drawable, False, 0, (XEvent *)&ev);
XShmDetach (dpy, &info);
XSync (dpy, False);
XSetErrorHandler (old_handler);
XUnlockDisplay (dpy);
shmctl (info.shmid, IPC_RMID, NULL);
shmdt (info.shmaddr);
return _x_error_occurred;
}
static cairo_bool_t
xorg_has_buggy_send_shm_completion_event(cairo_xlib_display_t *display,
cairo_xlib_shm_display_t *shm)
{
Display *dpy = display->display;
/* As libXext sets the SEND_EVENT bit in the ShmCompletionEvent,
* the Xserver may crash if it does not take care when processing
* the event type. For instance versions of Xorg prior to 1.11.1
@ -1141,8 +1193,12 @@ xorg_has_buggy_send_shm_completion_event(Display *dpy)
*
* Remove the SendEvent bit (0x80) before doing range checks on event type.
*/
return (strstr (ServerVendor (dpy), "X.Org") != NULL &&
VendorRelease (dpy) < XORG_VERSION_ENCODE(1,11,0,1));
if (strstr (ServerVendor (dpy), "X.Org") != NULL &&
VendorRelease (dpy) < XORG_VERSION_ENCODE(1,11,0,1))
return TRUE;
/* For everyone else check that no error is generated */
return has_broken_send_shm_event (display, shm);
}
void
@ -1162,6 +1218,15 @@ _cairo_xlib_display_init_shm (cairo_xlib_display_t *display)
if (unlikely (shm == NULL))
return;
codes = XInitExtension (display->display, SHMNAME);
if (codes == NULL) {
free (shm);
return;
}
shm->opcode = codes ->major_opcode;
shm->event = codes->first_event;
if (unlikely (_pqueue_init (&shm->info))) {
free (shm);
return;
@ -1177,16 +1242,12 @@ _cairo_xlib_display_init_shm (cairo_xlib_display_t *display)
DefaultVisual (display->display, scr),
CWOverrideRedirect, &attr);
if (xorg_has_buggy_send_shm_completion_event(display->display))
if (xorg_has_buggy_send_shm_completion_event(display, shm))
has_pixmap = 0;
shm->has_pixmaps = has_pixmap ? MIN_PIXMAP_SIZE : 0;
cairo_list_init (&shm->pool);
codes = XInitExtension (display->display, SHMNAME);
shm->opcode = codes ->major_opcode;
shm->event = codes->first_event;
cairo_list_init (&shm->surfaces);
display->shm = shm;