Re: SIGCHLD in vfork child context

[Paul Eggert <eggert@cs.ucla.edu>]

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mituharu@math.s.chiba-u.ac.jp wrote:
> Could you install a similar change to process.c, too?

Sure, done via the attached.

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From b1b570410f63e1f204677827530023ffc12218d6 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 21 May 2017 02:00:02 -0700
Subject: [PATCH] Work around macOS bug in create_process, too

* src/process.c (create_process) [DARWIN_OS]:
Reset SIGCHLD after vfork here, too.
---
 src/process.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/process.c b/src/process.c
index c301739..2a1c2ee 100644
--- a/src/process.c
+++ b/src/process.c
@@ -2051,11 +2051,16 @@ create_process (Lisp_Object process, char **new_argv, Lisp_Object current_dir)
 
 #ifdef DARWIN_OS
   /* Darwin doesn't let us run setsid after a vfork, so use fork when
-     necessary. */
+     necessary.  Also, reset SIGCHLD handling after a vfork, as
+     apparently macOS can mistakenly deliver SIGCHLD to the child.  */
   if (pty_flag)
     pid = fork ();
   else
-    pid = vfork ();
+    {
+      pid = vfork ();
+      if (pid == 0)
+	signal (SIGCHLD, SIG_DFL);
+    }
 #else
   pid = vfork ();
 #endif
-- 
2.7.4