signal.c: preserve errno

* signal.c (sighandler): preserve errno
  Patch by Steven Stewart-Gallus <sstewartgallus00@mylangara.bc.ca>
  [ruby-core:68172] [Bug #10866]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49746 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Wed Feb 25 18:12:11 2015  Eric Wong  <e@80x24.org>
+
+	* signal.c (sighandler): preserve errno
+	  Patch by Steven Stewart-Gallus <sstewartgallus00@mylangara.bc.ca>
+	  [ruby-core:68172] [Bug #10866]
+
 Wed Feb 25 15:59:35 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* dir.c (push_pattern, push_glob): make globbed file names same

signal.c

@@ -691,11 +691,15 @@ signal_enque(int sig)
 static RETSIGTYPE
 sighandler(int sig)
 {
+    int old_errnum = errno;
+
     signal_enque(sig);
     rb_thread_wakeup_timer_thread();
 #if !defined(BSD_SIGNAL) && !defined(POSIX_SIGNAL)
     ruby_signal(sig, sighandler);
 #endif
+
+    errno = old_errnum;
 }
 
 int