Fix assertion failures on FreeBSD due to kevent() returning multiple entries for the same file event source.

Maintain linked lists of all returned events for each event source, instead of supporting just a single event per event source.

system/BReactor_badvpn.c

@@ -193,20 +193,21 @@ static void set_kevent_fd_pointers (BReactor *bsys)
     for (int i = 0; i < bsys->kevent_results_num; i++) {
         struct kevent *event = &bsys->kevent_results[i];
         ASSERT(event->udata)
+        
         int *tag = event->udata;
         switch (*tag) {
             case KEVENT_TAG_FD: {
                 BFileDescriptor *bfd = UPPER_OBJECT(tag, BFileDescriptor, kevent_tag);
                 ASSERT(bfd->active)
-                ASSERT(!bfd->kevent_returned_ptr)
-                bfd->kevent_returned_ptr = (int **)&event->udata;
+                bsys->kevent_prev_event[i] = bfd->kevent_last_event;
+                bfd->kevent_last_event = i;
             } break;
             
             case KEVENT_TAG_KEVENT: {
                 BReactorKEvent *kev = UPPER_OBJECT(tag, BReactorKEvent, kevent_tag);
                 ASSERT(kev->reactor == bsys)
-                ASSERT(!kev->kevent_returned_ptr)
-                kev->kevent_returned_ptr = (int **)&event->udata;
+                bsys->kevent_prev_event[i] = kev->kevent_last_event;
+                kev->kevent_last_event = i;
             } break;
             
             default:
@@ -873,7 +874,8 @@ int BReactor_Exec (BReactor *bsys)
         // dispatch kevent
         if (bsys->kevent_results_pos < bsys->kevent_results_num) {
             // grab event
-            struct kevent *event = &bsys->kevent_results[bsys->kevent_results_pos];
+            int event_index = bsys->kevent_results_pos;
+            struct kevent *event = &bsys->kevent_results[event_index];
             bsys->kevent_results_pos++;
             
             // check if the event was removed
@@ -888,10 +890,11 @@ int BReactor_Exec (BReactor *bsys)
                     // get BFileDescriptor
                     BFileDescriptor *bfd = UPPER_OBJECT(tag, BFileDescriptor, kevent_tag);
                     ASSERT(bfd->active)
-                    ASSERT(bfd->kevent_returned_ptr == (int **)&event->udata)
                     
-                    // zero pointer to the kevent entry
-                    bfd->kevent_returned_ptr = NULL;
+                    // when we get to the last event for this fd, reset kevent_last_event
+                    if (event_index == bfd->kevent_last_event) {
+                        bfd->kevent_last_event = -1;
+                    }
                     
                     // calculate event to report
                     int events = 0;
@@ -917,10 +920,11 @@ int BReactor_Exec (BReactor *bsys)
                     // get BReactorKEvent
                     BReactorKEvent *kev = UPPER_OBJECT(tag, BReactorKEvent, kevent_tag);
                     ASSERT(kev->reactor == bsys)
-                    ASSERT(kev->kevent_returned_ptr == (int **)&event->udata)
                     
-                    // zero pointer to the kevent entry
-                    kev->kevent_returned_ptr = NULL;
+                    // when we get to the last event for this fd, reset kevent_last_event
+                    if (event_index == kev->kevent_last_event) {
+                        kev->kevent_last_event = -1;
+                    }
                     
                     // call handler
                     BLog(BLOG_DEBUG, "Dispatching kevent");
@@ -1109,8 +1113,8 @@ int BReactor_AddFileDescriptor (BReactor *bsys, BFileDescriptor *bs)
     // set kevent tag
     bs->kevent_tag = KEVENT_TAG_FD;
     
-    // set kevent returned pointer
-    bs->kevent_returned_ptr = NULL;
+    // have no events
+    bs->kevent_last_event = -1;
     
     #endif
     
@@ -1163,9 +1167,13 @@ void BReactor_RemoveFileDescriptor (BReactor *bsys, BFileDescriptor *bs)
     // delete kevents
     update_kevent_fd_events(bsys, bs, 0);
     
-    // write through kevent returned pointer
-    if (bs->kevent_returned_ptr) {
-        *bs->kevent_returned_ptr = NULL;
+    // invalidate any events
+    int event_index = bs->kevent_last_event;
+    while (event_index != -1) {
+        ASSERT(event_index >= 0 && event_index < bsys->kevent_results_num)
+        struct kevent *event = &bsys->kevent_results[event_index];
+        event->udata = NULL;
+        event_index = bsys->kevent_prev_event[event_index];
     }
     
     #endif
@@ -1316,8 +1324,8 @@ int BReactorKEvent_Init (BReactorKEvent *o, BReactor *reactor, BReactorKEvent_ha
     // set kevent tag
     o->kevent_tag = KEVENT_TAG_KEVENT;
     
-    // set kevent returned pointer
-    o->kevent_returned_ptr = NULL;
+    // have no events
+    o->kevent_last_event = -1;
     
     DebugObject_Init(&o->d_obj);
     DebugCounter_Increment(&o->reactor->d_kevent_ctr);
@@ -1326,12 +1334,17 @@ int BReactorKEvent_Init (BReactorKEvent *o, BReactor *reactor, BReactorKEvent_ha
 
 void BReactorKEvent_Free (BReactorKEvent *o)
 {
+    BReactor *reactor = o->reactor;
     DebugObject_Free(&o->d_obj);
-    DebugCounter_Decrement(&o->reactor->d_kevent_ctr);
-    
-    // write through kevent returned pointer
-    if (o->kevent_returned_ptr) {
-        *o->kevent_returned_ptr = NULL;
+    DebugCounter_Decrement(&reactor->d_kevent_ctr);
+    
+    // invalidate any events
+    int event_index = o->kevent_last_event;
+    while (event_index != -1) {
+        ASSERT(event_index >= 0 && event_index < reactor->kevent_results_num)
+        struct kevent *event = &reactor->kevent_results[event_index];
+        event->udata = NULL;
+        event_index = reactor->kevent_prev_event[event_index];
     }
     
     // delete kevent
@@ -1340,7 +1353,7 @@ void BReactorKEvent_Free (BReactorKEvent *o)
     event.ident = o->ident;
     event.filter = o->filter;
     event.flags = EV_DELETE;
-    ASSERT_FORCE(kevent(o->reactor->kqueue_fd, &event, 1, NULL, 0, NULL) == 0)
+    ASSERT_FORCE(kevent(reactor->kqueue_fd, &event, 1, NULL, 0, NULL) == 0)
 }
 
 #endif

system/BReactor_badvpn.h

@@ -203,7 +203,7 @@ typedef struct BFileDescriptor_t {
     
     #ifdef BADVPN_USE_KEVENT
     int kevent_tag;
-    int **kevent_returned_ptr;
+    int kevent_last_event;
     #endif
     
     #ifdef BADVPN_USE_POLL
@@ -265,6 +265,7 @@ typedef struct {
     #ifdef BADVPN_USE_KEVENT
     int kqueue_fd;
     struct kevent kevent_results[BSYSTEM_MAX_RESULTS];
+    int kevent_prev_event[BSYSTEM_MAX_RESULTS];
     int kevent_results_num;
     int kevent_results_pos;
     #endif
@@ -531,7 +532,7 @@ typedef struct {
     uintptr_t ident;
     short filter;
     int kevent_tag;
-    int **kevent_returned_ptr;
+    int kevent_last_event;
     DebugObject d_obj;
 } BReactorKEvent;