[newlib-cygwin/cygwin-3_0-branch] Cygwin: signals: restore sigmask from context given to signal handler

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=a5da9128ebbe2df954b43c0127f00ef0d4d15ed4

commit a5da9128ebbe2df954b43c0127f00ef0d4d15ed4
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);
     }