tevent: maintain a list of disabled events in the poll backend

We need to avoid passing pollfd.events == 0, to poll(),
as it will report POLLERR and POLLHUP events, but our caller
does not expect the event handler to be called.

Signed-off-by: Stefan Metzmacher <metze@samba.org>

diff --git a/lib/tevent/tevent_poll.c b/lib/tevent/tevent_poll.c
index 792abefd48c97155d849855941cee0040d53aa68..9e2cf1ee05cdf85eb2aca4a8352bc3b438304e54 100644 (file)
--- a/lib/tevent/tevent_poll.c
+++ b/lib/tevent/tevent_poll.c
@@ -38,6 +38,13 @@ struct poll_event_context {
         * picked up yet by poll_event_loop_once
         */
        struct tevent_fd *fresh;
+       /*
+        * A DLIST for disabled fde's.
+        */
+       struct tevent_fd *disabled;
+       /*
+        * one or more events were deleted or disabled
+        */
        bool deleted;
 
        /*
@@ -66,6 +73,12 @@ static int poll_event_context_destructor(struct poll_event_context *poll_ev)
                DLIST_REMOVE(poll_ev->fresh, fd);
        }
 
+       for (fd = poll_ev->disabled; fd; fd = fn) {
+               fn = fd->next;
+               fd->event_ctx = NULL;
+               DLIST_REMOVE(poll_ev->disabled, fd);
+       }
+
        if (poll_ev->signal_fd == -1) {
                /*
                 * Non-threaded, no signal pipe
@@ -220,8 +233,10 @@ static int poll_event_fd_destructor(struct tevent_fd *fde)
                ev->additional_data, struct poll_event_context);
 
        if (del_idx == UINT64_MAX) {
+               struct tevent_fd **listp =
+                       (struct tevent_fd **)fde->additional_data;
 
-               DLIST_REMOVE(poll_ev->fresh, fde);
+               DLIST_REMOVE((*listp), fde);
                goto done;
        }
 
@@ -256,10 +271,18 @@ _PRIVATE_ void tevent_poll_event_add_fd_internal(struct tevent_context *ev,
 {
        struct poll_event_context *poll_ev = talloc_get_type_abort(
                ev->additional_data, struct poll_event_context);
+       struct tevent_fd **listp;
+
+       if (fde->flags != 0) {
+               listp = &poll_ev->fresh;
+       } else {
+               listp = &poll_ev->disabled;
+       }
 
        fde->additional_flags   = UINT64_MAX;
-       fde->additional_data    = NULL;
-       DLIST_ADD(poll_ev->fresh, fde);
+       fde->additional_data    = listp;
+
+       DLIST_ADD((*listp), fde);
        talloc_set_destructor(fde, poll_event_fd_destructor);
 }
 
@@ -327,11 +350,28 @@ static void poll_event_set_fd_flags(struct tevent_fd *fde, uint16_t flags)
        fde->flags = flags;
 
        if (idx == UINT64_MAX) {
+               struct tevent_fd **listp =
+                       (struct tevent_fd **)fde->additional_data;
+
+               /*
+                * We move it between the fresh and disabled lists.
+                */
+               DLIST_REMOVE((*listp), fde);
+               tevent_poll_event_add_fd_internal(ev, fde);
+               poll_event_wake_pollthread(poll_ev);
+               return;
+       }
+
+       if (fde->flags == 0) {
                /*
-                * poll_event_setup_fresh not yet called after this fde was
-                * added. We don't have to do anything to transfer the changed
-                * flags to the array passed to poll(2)
+                * We need to remove it from the array
+                * and move it to the disabled list.
                 */
+               poll_ev->fdes[idx] = NULL;
+               poll_ev->deleted = true;
+               DLIST_REMOVE(ev->fd_events, fde);
+               tevent_poll_event_add_fd_internal(ev, fde);
+               poll_event_wake_pollthread(poll_ev);
                return;
        }
 
@@ -602,7 +642,8 @@ static int poll_event_loop_wait(struct tevent_context *ev,
               ev->timer_events ||
               ev->immediate_events ||
               ev->signal_events ||
-              poll_ev->fresh) {
+              poll_ev->fresh ||
+              poll_ev->disabled) {
                int ret;
                ret = _tevent_loop_once(ev, location);
                if (ret != 0) {