[glib] gmain: Save errno when handling unix signals

[Ryan Lortie <desrt src gnome org>]

commit 7c70377abf045ed93e18227e424b473c087f12df
Author: Ryan Lortie <desrt desrt ca>
Date:   Fri Dec 19 17:05:59 2014 -0500

    gmain: Save errno when handling unix signals
    
    Our signal handler calls write() on a pipe or an eventfd in order to
    deliver the notification.  It's unlikely, but this could fail, setting
    errno.  We even check the case that it fails with EINTR.
    
    If it does set errno, then it has potentially blown away the value or
    errno that the preempted code cared about (ie: if the signal arrived
    shortly after a system call but before errno was checked).
    
    Wrap the handler with code to save errno.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=741791

 glib/gmain.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/glib/gmain.c b/glib/gmain.c
index f1bb254..401baf0 100644
--- a/glib/gmain.c
+++ b/glib/gmain.c
@@ -5185,10 +5185,14 @@ g_child_watch_dispatch (GSource    *source,
 static void
 g_unix_signal_handler (int signum)
 {
+  gint saved_errno = errno;
+
   unix_signal_pending[signum] = TRUE;
   any_unix_signal_pending = TRUE;
 
   g_wakeup_signal (glib_worker_context->wakeup);
+
+  errno = saved_errno;
 }
 
 #endif /* !G_OS_WIN32 */