use same close logic for stderr as stdout

Avoids sending SIGPIPE to child processes after their parent exits
if they attempt to write to stderr.

Analysis and patch from JD Paul; patch reworked by Jakub Jelen and
myself. bz#2071; ok dtucker@

1 files changed, 5 insertions, 3 deletions

diff --git a/channels.c b/channels.c
index 19da16eb3..657381b80 100644
--- a/channels.c
+++ b/channels.c
@@ -2100,16 +2100,18 @@ channel_handle_efd_read(struct ssh *ssh, Channel *c,
     fd_set *readset, fd_set *writeset)
 {
         char buf[CHAN_RBUF];
-        int r;
         ssize_t len;
+        int r, force;
+
+        force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
 
-        if (!c->detach_close && !FD_ISSET(c->efd, readset))
+        if (c->efd == -1 || (!force && !FD_ISSET(c->efd, readset)))
                 return 1;
 
         len = read(c->efd, buf, sizeof(buf));
         debug2("channel %d: read %zd from efd %d", c->self, len, c->efd);
         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
-            errno == EWOULDBLOCK) && !c->detach_close)))
+            errno == EWOULDBLOCK) && !force)))
                 return 1;
         if (len <= 0) {
                 debug2("channel %d: closing read-efd %d",