master 8ed97a8: Make child signal read pipe non-blocking.

[Philipp Stephani]

branch: master
commit 8ed97a8d543b9596166c670212265dabc44aa3d5
Author: Philipp Stephani <phst@google.com>
Commit: Philipp Stephani <phst@google.com>

    Make child signal read pipe non-blocking.
    
    Otherwise Emacs might hang when trying to read the pipe twice in a
    row.  This is consistent with the other file descriptors we pass to
    'pselect'.
    
    * src/process.c (child_signal_init): Make read end of pipe
    non-blocking.
---
 src/process.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/process.c b/src/process.c
index 09f8790..5710598 100644
--- a/src/process.c
+++ b/src/process.c
@@ -7179,6 +7179,8 @@ child_signal_init (void)
      exits.  */
   eassert (0 <= fds[0]);
   eassert (0 <= fds[1]);
+  if (fcntl (fds[0], F_SETFL, O_NONBLOCK) != 0)
+    emacs_perror ("fcntl");
   add_read_fd (fds[0], child_signal_read, NULL);
   fd_callback_info[fds[0]].flags &= ~KEYBOARD_FD;
   child_signal_read_fd = fds[0];