[Wayland-bugs] [Bug 99845] Enabling button scrolling on L/R with middle button emulation enabled triggers a bug

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=99845

            Bug ID: 99845
           Summary: Enabling button scrolling on L/R with middle button
                    emulation enabled triggers a bug
           Product: Wayland
           Version: unspecified
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: libinput
          Assignee: wayland-bugs at lists.freedesktop.org
          Reporter: peter.hutterer at who-t.net

Enabling button scrolling on the left or right button with middle button
emulation enabled triggers a timer bug assertion in libinput. Cause is that
once the middle button expires, it sends the button event with the original
event timestamp (but delayed by the timeout).

That feeds into the scroll button emulation code which triggers the next
timer for the scroll expiry, based on the event timestamp. That triggers the
assertion in the timer system because it checks the current time against the
event timestamp (which is now in the past).


Output from the test suite:
    litest debug: event18: tagged as LIBINPUT_MODEL_TRACKBALL
    litest debug: event18: tagged as LIBINPUT_MODEL_LOGITECH_MARBLE_MOUSE
    litest debug: event18: tagged as ID_INPUT_TRACKBALL
    litest info: input device 'litest Logitech USB Trackball',
/dev/input/event18 is tagged by udev as: Mouse Trackball
    litest info: input device 'litest Logitech USB Trackball',
/dev/input/event18 is a pointer caps
    litest debug: middlebuttonstate: MIDDLEBUTTON_IDLE →
MIDDLEBUTTON_EVENT_L_DOWN → MIDDLEBUTTON_LEFT_DOWN, rc 1
    litest error: libinput bug: timer offset negative (-100109)
    FAILED: aborting
    libinput bug triggered, aborting.
    in litest_log_handler() (litest.c:803)

    Backtrace:
    0: litest_fail_condition() (.today/libinput/test/litest.c:284)
    1: litest_log_handler() (.today/libinput/test/litest.c:804)
    2: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10 (log_msg_va+0x52)
[0x7fab423f5206]
    3: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10 (log_msg+0xba)
[0x7fab423f52c3]
    4: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10
(libinput_timer_set+0x5c) [0x7fab4241d6c0]
    5: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10
(evdev_button_scroll_button+0x53) [0x7fab423fda3c]
    6: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10
(evdev_pointer_notify_button+0x4a) [0x7fab423fdb28]
    7: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10
(middlebutton_post_event+0x2c) [0x7fab42405246]
    8: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10
(evdev_middlebutton_ldown_handle_event+0x14d) [0x7fab42405423]
    9: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10
(evdev_middlebutton_handle_event+0x87) [0x7fab42405b8f]
    10: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10
(evdev_middlebutton_handle_timeout+0x38) [0x7fab42405f26]
    11: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10
(libinput_timer_handler+0x110) [0x7fab4241d8d7]
    12: /home/whot/tmp/today/libinput/src/.libs/libinput.so.10
(libinput_dispatch+0xbe) [0x7fab423f8e10]
    13: litest_button_scroll() (.today/libinput/test/litest.c:2094)
    14: pointer_scroll_button() (.today/libinput/test/test-pointer.c:999)
    15: /lib64/libcheck.so.0 (srunner_run+0x869) [0x7fab42839db9]
    16: litest_run_suite() (.today/libinput/test/litest.c:945)
    17: litest_run() (.today/libinput/test/litest.c:998)
    18: main() (.today/libinput/test/litest.c:3581)
    19: /lib64/libc.so.6 (__libc_start_main+0xf1) [0x7fab412ed401]
    20: ./test/libinput-test-suite-runner (_start+0x2a) [0x40980a]
    21: ? (?+0x2a) [0x2a]

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