[newlib-cygwin] Cygwin: signals: restore sigmask from context given to signal handler

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=d3a69d32b1b21b3885d3c8222c0c316be646ddf1

commit d3a69d32b1b21b3885d3c8222c0c316be646ddf1
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Wed Apr 3 18:14:30 2019 +0200

    Cygwin: signals: restore sigmask from context given to signal handler
    
    In case SA_SIGINFO flag is given, the signal handler may change
    the context and the application is supposed to pick up from the
    changed context.  So far we don't do that, so the context given
    to the signal handler is basically read-only, unless the signal
    handler calls setcontext or swapcontext.
    
    For a start, restore the thread's signal mask from the uc_sigmask
    value of the context given to the signal handler.
    
    If that's feasible for Cygwin, we restore the entire context from
    the context changed by the signal handler in a followup patch.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/exceptions.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index da4348f..a9b3781 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -1818,7 +1818,8 @@ _cygtls::call_signal_handler ()
 
       incyg = true;
 
-      set_signal_mask (_my_tls.sigmask, this_oldmask);
+      set_signal_mask (_my_tls.sigmask, (this_sa_flags & SA_SIGINFO)
+					? context.uc_sigmask : this_oldmask);
       if (this_errno >= 0)
 	set_errno (this_errno);
     }