From a9f2765b4febea0a02b286f54abe5c2f1cfc2bb6 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Thu, 13 Oct 2016 11:25:27 -0600
Subject: [PATCH] another errno in a signal handler

---
 racket/src/racket/src/port.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/racket/src/racket/src/port.c b/racket/src/racket/src/port.c
index 26995ba6e4..4cbe365c25 100644
--- a/racket/src/racket/src/port.c
+++ b/racket/src/racket/src/port.c
@@ -10917,12 +10917,14 @@ void scheme_signal_received_at(void *h)
 {
 #if defined(FILES_HAVE_FDS)
   int put_ext_event_fd = *(int *)h;
+  int saved_errno = errno;
   if (put_ext_event_fd) {
     int v;
     do {
       v = write(put_ext_event_fd, "!", 1);
     } while ((v == -1) && (errno == EINTR));
   }
+  errno = saved_errno;
 #endif
 #if defined(WINDOWS_PROCESSES) || defined(WINDOWS_FILE_HANDLES)
   ReleaseSemaphore(*(OS_SEMAPHORE_TYPE *)h, 1, NULL);