Cygwin: always add sigmask to child info

Even after fork, we might need the parent sigmask without having
access to the real _main_tls. There's a short time at process startup,
when _main_tls points to the system-allocated stack, but wait_sig is
already running. If we can't lock _main_tls, because find_tls can't
find it yet, we now access the parent's sigmask via child_info.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

1 files changed, 14 insertions, 4 deletions

diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc
index 62df96652..987dfea37 100644
--- a/winsup/cygwin/sigproc.cc
+++ b/winsup/cygwin/sigproc.cc
@@ -820,7 +820,7 @@ child_info::child_info (unsigned in_cb, child_info_types chtype,
   msv_count (0), cb (in_cb), intro (PROC_MAGIC_GENERIC),
   magic (CHILD_INFO_MAGIC), type (chtype), cygheap (::cygheap),
   cygheap_max (::cygheap_max), flag (0), retry (child_info::retry_count),
-  rd_proc_pipe (NULL), wr_proc_pipe (NULL)
+  rd_proc_pipe (NULL), wr_proc_pipe (NULL), sigmask (_my_tls.sigmask)
 {
   fhandler_union_cb = sizeof (fhandler_union);
   user_h = cygwin_user_h;
@@ -902,7 +902,6 @@ cygheap_exec_info::alloc ()
 					 sizeof (cygheap_exec_info)
 					 + (chld_procs.count ()
 					    * sizeof (children[0])));
-  res->sigmask = _my_tls.sigmask;
   return res;
 }
 
@@ -1353,9 +1352,20 @@ wait_sig (VOID *)
       threadlist_t *tl_entry;
       if (!pack.mask)
 	{
+	  /* There's a short time at process startup of a forked process,
+	     when _main_tls points to the system-allocated stack, not to
+	     the parent thread. In that case find_tls fails, and we fetch
+	     the sigmask from the child_info passed from the parent. */
 	  tl_entry = cygheap->find_tls (_main_tls);
-	  dummy_mask = _main_tls->sigmask;
-	  cygheap->unlock_tls (tl_entry);
+	  if (tl_entry)
+	    {
+	      dummy_mask = _main_tls->sigmask;
+	      cygheap->unlock_tls (tl_entry);
+	    }
+	  else if (child_proc_info)
+	    dummy_mask = child_proc_info->sigmask;
+	  else
+	    dummy_mask = 0;
 	  pack.mask = &dummy_mask;
 	}