Try to avoid malloc SEGVs on Cygwin.

* callproc.c, process.h (block_child_signal, unblock_child_signal):
Now extern.
* emacs.c (main): Catch SIGCHLD just before initializing gfilenotify.
* process.c (catch_child_signal): Block SIGCHLD while futzing with
the SIGCHLD handler, since the code is not atomic and (due to glib)
signals may be arriving now.
* sysdep.c (init_signals): Do not catch child signals here;
'main' now does that later, at a safer time.

Fixes: debbugs:14569

1 files changed, 2 insertions, 0 deletions

diff --git a/src/process.c b/src/process.c
index 3e31dede4c2..6df1bf7eff7 100644
--- a/src/process.c
+++ b/src/process.c
@@ -7084,11 +7084,13 @@ catch_child_signal (void)
 #endif
 
   emacs_sigaction_init (&action, deliver_child_signal);
+  block_child_signal ();
   sigaction (SIGCHLD, &action, &old_action);
   eassert (! (old_action.sa_flags & SA_SIGINFO));
   if (old_action.sa_handler != SIG_DFL && old_action.sa_handler != SIG_IGN
       && old_action.sa_handler != deliver_child_signal)
     lib_child_handler = old_action.sa_handler;
+  unblock_child_signal ();
 }