This effectively gets swaywm/wlroots#1499 to the point where
functionality somewhat preserved and no crash happens.
We still can have only one cursor, but we can control it from multiple
seats in time-sharing manner by entering/leaving output.
xdg_popups can be destroyed by the compositor when closed. When this happens,
wlroots makes the xdg_popup surface inert and resets the xdg_surface role to
NONE.
Currently, wlroots sends a protocol error and asserts that an xdg_surface has
a role when committed. This is racy if at the same time the client commits an
xdg_popup and the compositor closes it. This patch removes the assertion and
ignores commits on xdg_surfaces without a role set.
We were previously exporting DMA-BUFs when receiving the capture_output
request, and sending a done event on wlr_output.events.precommit. Instead,
export and send done on wlr_output.events.commit.
When performing a modeset, the DRM backend will request a page-flip
event. However frame_pending wasn't set to true, so any subsequent
wlr_output_schedule_frame calls would imemdiately trigger a synthetic
frame event, asking the compositor to submit a new frame. Committing the
new frame fails with "a page-flip is already pending" error in the DRM
backend.
When an output is disabled one last pageflip will happen to disable it.
Currently this pageflip causes a frame event.
Since the output is disabled we don't want to send this frame event.
The resource field of wlr_xdg_positioner is never initialized or
accessed within wlroots. The wl_resource for this interface is stored
in the wlr_xdg_positioner_resource struct.
We already mostly did this, but there were a couple of branches
(`calloc` failures) where we'd bail without letting the other side know.
Refs swaywm/sway#4007. Likely not going to be a real improvement there
(if `calloc` fails you're already pretty screwed), but it does address a
theoretical possibility.
It seems that if we ever try to reply to a selection request after
another has been sent by the same requestor (we reply in FIFO order),
the requestor never reads from it, and we end up stalling forever on a
transfer that will never complete.
It appears that `XCB_SELECTION_REQUEST` has some sort of singleton
semantics, and new requests for the same selection are meant to replace
outstanding older ones. I couldn't find a reference for this, but
empirically this does seem to be the case.
Real (contrived) case where we don't currently do this, and things break:
* run fcitx
* run Slack
* wl-copy < <(base64 /opt/firefox/libxul.so) # or some other large file
* focus Slack (no need to paste)
fcitx will send in an `XCB_SELECTION_REQUEST`, and we'll start
processing it. Immediately after, Slack sends its own. fcitx hangs for a
long, long time. In the meantime, Slack retries and sends another
selection request. We now have two pending requests from Slack.
Eventually fcitx gives up (or it can be `pkill`'d), and we start
processing the first request Slack gave us (FIFO). Slack (Electron?)
isn't listening on the other end anymore, and this transfer never
completes. The X11 clipboard becomes unusable until Slack is killed.
After this patch, the clipboard is immediately usable again after fcitx
bails. Also added a bunch of debug-level logging that makes diagnosing
this sort of issue easier.
Refs swaywm/sway#4007.
When debugging Xwayland-related issues, a common first step in debugging
has been to ask the reporter to move their real Xwayland to
/usr/bin/Xwayland.bin, and create a shell script starting Xwayland with
extra arguments under the original /usr/bin/Xwayland location.
Introducing a `WLR_XWAYLAND` environment variable makes this less
invasive, by allowing the user to swap out Xwayland without resorting to
global system changes (or source patches).
Fixes#2425.
wlroots can only handle one outgoing transfer at a time, so it keeps a
list of pending selections. The head of the list is the currently-active
selection, and when that transfer completes and is destroyed, the next
one is started.
The trouble is when you have a transfer to some app that is misbehaving.
fcitx is one such application. With really large transfers, fcitx will
hang and never wake up again. So, you can end up with a transfer list
that looks like this:
| T1: started | T2: pending | T3: pending | T4: pending |
The file descriptor for transfer T1 is registered in libwayland's epoll
loop. The rest are waiting in wlroots' list.
As a user, you want your clipboard back, so you `pkill fcitx`. Now
Xwayland sends `XCB_DESTROY_NOTIFY` to let us know to give up. We clean
up T4 first.
Due to a bug in wlroots code, we register the (fd, transfer data
pointer) pair for T1 with libwayland *again*, despite it already being
registered. We do this 2 more times as we remove T3 and T2.
Finally, we remove T1 and `free` all the memory associated with it,
before `close`-ing its transfer file descriptor.
However, we still have 3 copies of T1's file descriptor left in the
epoll loop, since we erroneously added them as part of removing T2/3/4.
When we `close` the file descriptor as part of T1's teardown, we
actually cause the epoll loop to wake up the next time around, saying
"this file descriptor has activity!" (it was closed, so `read`-ing would
normally return 0 to let us know of EOF).
But instead of returning 0, it returns -1 with `EBADF`, because the file
descriptor has already been closed. And finally, as part of error-handling
this, we access the transfer pointer, which was `free`'d. And we crash.
This one was awful to track down, but calls to `wlr_log` with %m have
the errno masked by the `isatty` call in `log_stderr`. Switch them to
`wlr_log_errno` instead.
Cue quality "how can read(2) POSSIBLY be returning ENOTTY?" moments.
