Commit 6c531c43340af909b95d0814456ef2b828b1ea3c
2022-02-21T11:35:31
Correct handling of sentinel events when polling without removing events Fixes https://github.com/libsdl-org/SDL/issues/5350
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diff --git a/src/events/SDL_events.c b/src/events/SDL_events.c
index 5611f39..d3e219d 100644
--- a/src/events/SDL_events.c
+++ b/src/events/SDL_events.c
@@ -660,7 +660,7 @@ static int
SDL_PeepEventsInternal(SDL_Event * events, int numevents, SDL_eventaction action,
Uint32 minType, Uint32 maxType, SDL_bool include_sentinel)
{
- int i, used;
+ int i, used, sentinels_expected = 0;
/* Don't look after we've quit */
if (!SDL_AtomicGet(&SDL_EventQ.active)) {
@@ -723,8 +723,15 @@ SDL_PeepEventsInternal(SDL_Event * events, int numevents, SDL_eventaction action
}
if (type == SDL_POLLSENTINEL) {
/* Special handling for the sentinel event */
- if (!include_sentinel || SDL_AtomicGet(&SDL_sentinel_pending) > 0) {
- /* Skip it, we don't want to include it or there's another one pending */
+ if (!include_sentinel) {
+ /* Skip it, we don't want to include it */
+ continue;
+ }
+ if (!events || action != SDL_GETEVENT) {
+ ++sentinels_expected;
+ }
+ if (SDL_AtomicGet(&SDL_sentinel_pending) > sentinels_expected) {
+ /* Skip it, there's another one pending */
continue;
}
}
@@ -991,6 +998,7 @@ SDL_WaitEventTimeout(SDL_Event * event, int timeout)
SDL_Window *wakeup_window;
Uint32 start, expiration;
SDL_bool include_sentinel = (timeout == 0) ? SDL_TRUE : SDL_FALSE;
+ int result;
/* If there isn't a poll sentinel event pending, pump events and add one */
if (SDL_AtomicGet(&SDL_sentinel_pending) == 0) {
@@ -998,33 +1006,34 @@ SDL_WaitEventTimeout(SDL_Event * event, int timeout)
}
/* First check for existing events */
- switch (SDL_PeepEventsInternal(event, 1, SDL_GETEVENT, SDL_FIRSTEVENT, SDL_LASTEVENT, include_sentinel)) {
- case -1:
+ result = SDL_PeepEventsInternal(event, 1, SDL_GETEVENT, SDL_FIRSTEVENT, SDL_LASTEVENT, include_sentinel);
+ if (result < 0) {
return 0;
- case 0:
+ }
+ if (include_sentinel) {
+ if (event) {
+ if (event->type == SDL_POLLSENTINEL) {
+ /* Reached the end of a poll cycle, and not willing to wait */
+ return 0;
+ }
+ } else {
+ /* Need to peek the next event to check for sentinel */
+ SDL_Event dummy;
+
+ if (SDL_PeepEventsInternal(&dummy, 1, SDL_PEEKEVENT, SDL_FIRSTEVENT, SDL_LASTEVENT, SDL_TRUE) &&
+ dummy.type == SDL_POLLSENTINEL) {
+ SDL_PeepEventsInternal(&dummy, 1, SDL_GETEVENT, SDL_POLLSENTINEL, SDL_POLLSENTINEL, SDL_TRUE);
+ /* Reached the end of a poll cycle, and not willing to wait */
+ return 0;
+ }
+ }
+ }
+ if (result == 0) {
if (timeout == 0) {
/* No events available, and not willing to wait */
return 0;
}
- break;
- default:
- if (include_sentinel) {
- if (event) {
- if (event->type == SDL_POLLSENTINEL) {
- /* Reached the end of a poll cycle, and not willing to wait */
- return 0;
- }
- } else {
- /* Need to peek the next event to check for sentinel */
- SDL_Event dummy;
-
- if (SDL_PeepEventsInternal(&dummy, 1, SDL_PEEKEVENT, SDL_FIRSTEVENT, SDL_LASTEVENT, SDL_TRUE) &&
- dummy.type == SDL_POLLSENTINEL) {
- /* Reached the end of a poll cycle, and not willing to wait */
- return 0;
- }
- }
- }
+ } else {
/* Has existing events */
return 1;
}