1 files changed, 76 insertions, 0 deletions
diff --git a/src/port/pqsignal.c b/src/port/pqsignal.c
new file mode 100644
index 00000000000..ffb6f843308
--- /dev/null
+++ b/src/port/pqsignal.c
@@ -0,0 +1,76 @@
+/*-------------------------------------------------------------------------
+ *
+ * pqsignal.c
+ *	  reliable BSD-style signal(2) routine stolen from RWW who stole it
+ *	  from Stevens...
+ *
+ * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/port/pqsignal.c
+ *
+ *	A NOTE ABOUT SIGNAL HANDLING ACROSS THE VARIOUS PLATFORMS.
+ *
+ *	pg_config.h defines the macro HAVE_POSIX_SIGNALS for some platforms and
+ *	not for others.  We use that here to decide how to handle signalling.
+ *
+ *	Ultrix and SunOS provide BSD signal(2) semantics by default.
+ *
+ *	SVID2 and POSIX signal(2) semantics differ from BSD signal(2)
+ *	semantics.	We can use the POSIX sigaction(2) on systems that
+ *	allow us to request restartable signals (SA_RESTART).
+ *
+ *	Some systems don't allow restartable signals at all unless we
+ *	link to a special BSD library.
+ *
+ *	We devoutly hope that there aren't any Unix-oid systems that provide
+ *	neither POSIX signals nor BSD signals.	The alternative is to do
+ *	signal-handler reinstallation, which doesn't work well at all.
+ *
+ *	Windows, of course, is resolutely in a class by itself.  This file
+ *	should not get compiled at all on Windows.  We have an emulation of
+ *	pqsignal() in src/backend/port/win32/signal.c for the backend
+ *	environment; frontend programs are out of luck.
+ * ------------------------------------------------------------------------
+ */
+
+#include "c.h"
+
+#include <signal.h>
+
+#ifndef WIN32
+
+/*
+ * Set up a signal handler for signal "signo"
+ *
+ * Returns the previous handler.  It's expected that the installed handler
+ * will persist across multiple deliveries of the signal (unlike the original
+ * POSIX definition of signal(2)).
+ */
+pqsigfunc
+pqsignal(int signo, pqsigfunc func)
+{
+#if !defined(HAVE_POSIX_SIGNALS)
+	return signal(signo, func);
+#else
+	struct sigaction act,
+				oact;
+
+	act.sa_handler = func;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = 0;
+	if (signo != SIGALRM)
+		act.sa_flags |= SA_RESTART;
+#ifdef SA_NOCLDSTOP
+	if (signo == SIGCHLD)
+		act.sa_flags |= SA_NOCLDSTOP;
+#endif
+	if (sigaction(signo, &act, &oact) < 0)
+		return SIG_ERR;
+	return oact.sa_handler;
+#endif   /* !HAVE_POSIX_SIGNALS */
+}
+
+#endif /* WIN32 */