From 6056dae7f43492b6f1ad1708552e7a9c4994d9eb Mon Sep 17 00:00:00 2001
From: normal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Sun, 19 Aug 2018 20:40:42 +0000
Subject: [PATCH] thread.c (rb_thread_fd_select): fix off-by-one with
 sigwait_fd

select(2) needs the nfds argument to be one higher than the
largest FD in the sets :x

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64475 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 thread.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/thread.c b/thread.c
index 8254c7dc0c..c756b53bea 100644
--- a/thread.c
+++ b/thread.c
@@ -4028,7 +4028,7 @@ rb_thread_fd_select(int max, rb_fdset_t * read, rb_fdset_t * write, rb_fdset_t *
             rb_fd_set(set.sigwait_fd, set.rset);
         else
             set.rset = init_set_fd(set.sigwait_fd, &set.orig_rset);
-        if (set.sigwait_fd > set.max) {
+        if (set.sigwait_fd >= set.max) {
             set.max = set.sigwait_fd + 1;
         }
     }