IO#close: do not enqueue redundant interrupts

Enqueuing multiple errors for one event causes spurious errors
down the line, as reported by Nikolay Vashchenko in
https://bugs.ruby-lang.org/issues/13632

* thread.c (rb_notify_fd_close): do not enqueue multiple interrupts
  [ruby-core:81581] [Bug #13632]
* test/ruby/test_io.rb (test_single_exception_on_close):
  new test based on script from Nikolay

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59020 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 0 deletions

diff --git a/thread.c b/thread.c
index da834974bd..42159b3c19 100644
--- a/thread.c
+++ b/thread.c
@@ -2213,6 +2213,8 @@ rb_notify_fd_close(int fd)
 	if (wfd->fd == fd) {
 	    rb_thread_t *th = wfd->th;
 	    VALUE err = th->vm->special_exceptions[ruby_error_stream_closed];
+
+	    wfd->fd = -1; /* ensure we only enqueue once */
 	    rb_threadptr_pending_interrupt_enque(th, err);
 	    rb_threadptr_interrupt(th);
 	    busy = 1;