[newlib-cygwin] Revert "Cygwin: fix potential SEGV in sigwaitinfo/signalfd scenario"

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=b7399d5e6f8ad5b15cd725f66b3e49732393ef03

commit b7399d5e6f8ad5b15cd725f66b3e49732393ef03
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Fri Aug 16 16:36:20 2019 +0200

    Revert "Cygwin: fix potential SEGV in sigwaitinfo/signalfd scenario"
    
    This reverts commit 92115a83a4579635e253be2887d3706d28b477fd.
    
    This was utterly wrong.

Diff:
---
 winsup/cygwin/exceptions.cc | 17 +++--------------
 winsup/cygwin/release/3.1.0 |  3 ---
 2 files changed, 3 insertions(+), 17 deletions(-)

diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index 9bdf9f0..1765f43 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -1628,7 +1628,7 @@ _cygtls::call_signal_handler ()
       if (retaddr () == (__tlsstack_t) sigdelayed)
 	pop ();
 
-      debug_only_printf ("dealing with signal %d, handler %p", sig, func);
+      debug_only_printf ("dealing with signal %d", sig);
       this_sa_flags = sa_flags;
 
       sigset_t this_oldmask = set_process_mask_delta ();
@@ -1647,12 +1647,8 @@ _cygtls::call_signal_handler ()
 
       ucontext_t *thiscontext = NULL, context_copy;
 
-      /* Only make a context for SA_SIGINFO handlers, only if a handler
-         exists.  If handler is NULL, drop SA_SIGINFO flag to avoid
-	 accidental context access later in the function. */
-      if (!thisfunc)
-	this_sa_flags &= ~SA_SIGINFO;
-      else if (this_sa_flags & SA_SIGINFO)
+      /* Only make a context for SA_SIGINFO handlers */
+      if (this_sa_flags & SA_SIGINFO)
 	{
 	  context.uc_link = 0;
 	  context.uc_flags = 0;
@@ -1714,11 +1710,6 @@ _cygtls::call_signal_handler ()
       sig = 0;		/* Flag that we can accept another signal */
       unlock ();	/* unlock signal stack */
 
-      /* Handler may be NUll in sigwaitinfo/signalfd scenario.  Avoid
-	 crashing by calling a NULL function. */
-      if (!thisfunc)
-	goto skip_calling_handler;
-
       /* Alternate signal stack requested for this signal and alternate signal
 	 stack set up for this thread? */
       if (this_sa_flags & SA_ONSTACK
@@ -1826,8 +1817,6 @@ _cygtls::call_signal_handler ()
 	   signal handler. */
 	thisfunc (thissig, &thissi, thiscontext);
 
-skip_calling_handler:
-
       incyg = true;
 
       set_signal_mask (_my_tls.sigmask, (this_sa_flags & SA_SIGINFO)
diff --git a/winsup/cygwin/release/3.1.0 b/winsup/cygwin/release/3.1.0
index c9cb7c0..ccb63c3 100644
--- a/winsup/cygwin/release/3.1.0
+++ b/winsup/cygwin/release/3.1.0
@@ -71,6 +71,3 @@ Bug Fixes
 - 64 bit only: Avoid collisions between memory maps created with shmat
   and Windows datastructures during fork.
   Addresses: https://cygwin.com/ml/cygwin/2019-08/msg00107.html
-
-- Avoid a SEGV after using signalfd.
-  Addresses: https://cygwin.com/ml/cygwin/2019-08/msg00148.html