From: bones_was_here <bones_was_here@xonotic.au>
Date: Mon, 26 Feb 2024 18:53:26 +0000 (+1000)
Subject: sys: prevent loops in signal handlers
X-Git-Url: https://git.rm.cloudns.org/?a=commitdiff_plain;h=95ed24831ca8dcbf6ae8f886733c35ce2ad83272;p=xonotic%2Fdarkplaces.git

sys: prevent loops in signal handlers

Fixes https://gitlab.com/xonotic/xonotic/-/issues/377

Signed-off-by: bones_was_here <bones_was_here@xonotic.au>
---

diff --git a/host.h b/host.h
index 89ea1f11..986b3224 100644
--- a/host.h
+++ b/host.h
@@ -24,6 +24,7 @@ typedef enum host_state_e
 	host_init,
 	host_loading,
 	host_active,
+	host_failing, ///< crashing
 	host_failed ///< crashed or aborted, SDL dialog open
 } host_state_t;
 
diff --git a/sys_shared.c b/sys_shared.c
index 7ce69c31..fa733ebf 100644
--- a/sys_shared.c
+++ b/sys_shared.c
@@ -680,6 +680,9 @@ void Sys_Abort (const char *error, ...)
 	char string[MAX_INPUTLINE];
 	int i;
 
+	// Disable Sys_HandleSignal() but not Sys_HandleCrash()
+	host.state = host_shutdown;
+
 	// set output to blocking stderr
 	sys.outfd = fileno(stderr);
 #ifndef WIN32
@@ -712,11 +715,10 @@ void Sys_Abort (const char *error, ...)
 	VID_Shutdown();
 	S_StopAllSounds();
 
-	host.state = host_failed; // make Sys_HandleSignal() call exit()
+	host.state = host_failed; // make Sys_HandleSignal() call _Exit()
 	Sys_SDL_Dialog("Engine Abort", string);
 
 	fflush(stderr);
-
 	exit (1);
 }
 
@@ -952,7 +954,14 @@ static void Sys_HandleCrash(int sig)
 	char **btstrings;
 #endif
 	char dialogtext[3072];
-	const char *sigdesc = Sys_SigDesc(sig);
+	const char *sigdesc;
+
+	// Break any loop and disable Sys_HandleSignal()
+	if (host.state == host_failing || host.state == host_failed)
+		return;
+	host.state = host_failing;
+
+	sigdesc = Sys_SigDesc(sig);
 
 	// set output to blocking stderr and print header, backtrace, version
 	sys.outfd = fileno(stderr); // not async-signal-safe :(
@@ -1007,13 +1016,19 @@ static void Sys_HandleCrash(int sig)
 
 static void Sys_HandleSignal(int sig)
 {
-	const char *sigdesc = Sys_SigDesc(sig);
+	const char *sigdesc;
+
+	// Break any loop, eg if each Sys_Print triggers a SIGPIPE
+	if (host.state == host_shutdown || host.state == host_failing)
+		return;
+
+	sigdesc = Sys_SigDesc(sig);
 	Sys_Print("\nReceived ", 10);
 	Sys_Print(sigdesc, strlen(sigdesc));
 	Sys_Print(" signal, exiting...\n", 20);
 	if (host.state == host_failed)
 	{
-		// user is trying to kill the process while the dialog is open
+		// user is trying to kill the process while the SDL dialog is open
 		fflush(stderr); // not async-signal-safe :(
 		_Exit(sig);
 	}