From 5636f3a8a2d4564aaddf424d62723aac7f4d45fe Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Tue, 15 Mar 2011 21:36:36 -0700
Subject: [PATCH] Do not break application's signal handler installed with
 SA_SIGINFO

Gleb Natapov to sdl

If application installs SIGINT/SIGTERM signal handler with
sigaction(SA_SIGINFO) syscall before initializing SDL, after
initialization
of SDL signal handler will be reinstalled without SA_SIGINFO flag which
brings havoc when the signal handler is called. The breakage is done by
SDL_QuitInit()/SDL_QuitQuit() function. They use signal() to detect that
signal handler is already installed even in sigaction() is available.
---
 src/events/SDL_quit.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/events/SDL_quit.c b/src/events/SDL_quit.c
index d80eae2c8..65d6c0ce8 100644
--- a/src/events/SDL_quit.c
+++ b/src/events/SDL_quit.c
@@ -45,7 +45,19 @@ static void SDL_HandleSIG(int sig)
 /* Public functions */
 int SDL_QuitInit(void)
 {
-#ifdef HAVE_SIGNAL_H
+#ifdef HAVE_SIGACTION
+	struct sigaction action;
+	sigaction(SIGINT, NULL, &action);
+	if ( action.sa_handler == SIG_DFL && action.sa_sigaction == SIG_DFL ) {
+		action.sa_handler = SDL_HandleSIG;
+		sigaction(SIGINT, &action, NULL);
+	}
+	sigaction(SIGTERM, NULL, &action);
+	if ( action.sa_handler == SIG_DFL && action.sa_sigaction == SIG_DFL ) {
+		action.sa_handler = SDL_HandleSIG;
+		sigaction(SIGTERM, &action, NULL);
+	}
+#elif HAVE_SIGNAL_H
 	void (*ohandler)(int);
 
 	/* Both SIGINT and SIGTERM are translated into quit interrupts */
@@ -62,7 +74,19 @@ int SDL_QuitInit(void)
 }
 void SDL_QuitQuit(void)
 {
-#ifdef HAVE_SIGNAL_H
+#ifdef HAVE_SIGACTION
+	struct sigaction action;
+	sigaction(SIGINT, NULL, &action);
+	if ( action.sa_handler == SDL_HandleSIG ) {
+		action.sa_handler = SIG_DFL;
+		sigaction(SIGINT, &action, NULL);
+	}
+	sigaction(SIGTERM, NULL, &action);
+	if ( action.sa_handler == SDL_HandleSIG ) {
+		action.sa_handler = SIG_DFL;
+		sigaction(SIGTERM, &action, NULL);
+	}
+#elif HAVE_SIGNAL_H
 	void (*ohandler)(int);
 
 	ohandler = signal(SIGINT, SIG_DFL);