make sure stdout is non-blocking; ok djm@

diff --git a/usr.bin/ssh/channels.c b/usr.bin/ssh/channels.c
index f2f6267..65ea5d4 100644 (file)
--- a/usr.bin/ssh/channels.c
+++ b/usr.bin/ssh/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.417 2022/04/20 04:19:11 djm Exp $ */
+/* $OpenBSD: channels.c,v 1.418 2022/05/04 07:31:22 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -296,6 +296,8 @@ static void
 channel_register_fds(struct ssh *ssh, Channel *c, int rfd, int wfd, int efd,
     int extusage, int nonblock, int is_tty)
 {
+       int val;
+
        if (rfd != -1)
                fcntl(rfd, F_SETFD, FD_CLOEXEC);
        if (wfd != -1 && wfd != rfd)
@@ -321,15 +323,18 @@ channel_register_fds(struct ssh *ssh, Channel *c, int rfd, int wfd, int efd,
                 * restore their blocking state on exit to avoid interfering
                 * with other programs that follow.
                 */
-               if (rfd != -1 && !isatty(rfd) && fcntl(rfd, F_GETFL) == 0) {
+               if (rfd != -1 && !isatty(rfd) &&
+                   (val = fcntl(rfd, F_GETFL)) != -1 && !(val & O_NONBLOCK)) {
                        c->restore_block |= CHANNEL_RESTORE_RFD;
                        set_nonblock(rfd);
                }
-               if (wfd != -1 && !isatty(wfd) && fcntl(wfd, F_GETFL) == 0) {
+               if (wfd != -1 && !isatty(wfd) &&
+                   (val = fcntl(wfd, F_GETFL)) != -1 && !(val & O_NONBLOCK)) {
                        c->restore_block |= CHANNEL_RESTORE_WFD;
                        set_nonblock(wfd);
                }
-               if (efd != -1 && !isatty(efd) && fcntl(efd, F_GETFL) == 0) {
+               if (efd != -1 && !isatty(efd) &&
+                   (val = fcntl(efd, F_GETFL)) != -1 && !(val & O_NONBLOCK)) {
                        c->restore_block |= CHANNEL_RESTORE_EFD;
                        set_nonblock(efd);
                }