From 8718ed739d79d4792362172fee3c6bcdea8c5721 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter@cs.unisa.edu.au>
Date: Wed, 23 Apr 2008 16:04:08 +0930
Subject: [PATCH] dix: set up siglongjmp to jump to in case of a FatalError.

Calling FatalError from within xf86SignalHandler is not POSIX compliant (it
calls free() on the way out). So we set up a siglongjmp environment at the
start of main() and jump back here before we bring the server down.
---
 dix/main.c                     |   16 ++++++++++++++++
 hw/xfree86/common/xf86Events.c |    9 ++++++++-
 include/dix.h                  |    4 ++++
 3 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/dix/main.c b/dix/main.c
index f7824ee..cc17416 100644
--- a/dix/main.c
+++ b/dix/main.c
@@ -119,6 +119,12 @@ Equipment Corporation.
 #include "dpmsproc.h"
 #endif
 
+/**
+ * siglongjmp environment set up in Dispatch(). Used by xf86SignalHandler to
+ * jump out when a FatalError is needed.
+ */
+sigjmp_buf sigjmp_env;
+
 extern void Dispatch(void);
 
 char *ConnectionInfo;
@@ -247,9 +253,19 @@ main(int argc, char *argv[], char *envp[])
     int		i, j, k, error;
     char	*xauthfile;
     HWEventQueueType	alwaysCheckForInput[2];
+    int sig;
 
     display = "0";
 
+
+    /* Set up a signal longjump. If a SEGV or other signal will bring the
+     * server down, we jump here to be able to FatalError().
+     */
+    if ((sig = sigsetjmp(sigjmp_env, 0)))
+    {
+        FatalError("Aborting after receiving signal %d.\n", sig);
+    }
+
     InitGlobals();
     InitRegions();
 #ifdef XPRINT
diff --git a/hw/xfree86/common/xf86Events.c b/hw/xfree86/common/xf86Events.c
index d1e4393..a07f066 100644
--- a/hw/xfree86/common/xf86Events.c
+++ b/hw/xfree86/common/xf86Events.c
@@ -125,6 +125,7 @@ _X_EXPORT Bool VTSwitchEnabled = TRUE;	/* Allows run-time disabling for
                                          *BSD and for avoiding VT
                                          switches when using the DRI
                                          automatic full screen mode.*/
+extern sigjmp_buf sigjmp_env;
 
 extern fd_set EnabledDevices;
 
@@ -764,8 +765,14 @@ xf86SigHandler(int signo)
 #endif
 
   xorg_backtrace();
+  ErrorF("Caught signal %d. Server aborting.\n", signo);
 
-  FatalError("Caught signal %d.  Server aborting\n", signo);
+  /* Do not call FatalError() here. It will close down the devices and thus
+   * call free(), which is a no-no from within a signal handler.
+   * We have to siglongjmp out of here before we bring the server down.
+   * The sig longjmp environment was set up first thin in main().
+   */
+  siglongjmp(sigjmp_env, signo);
 }
 
 static void
diff --git a/include/dix.h b/include/dix.h
index 57ffee9..014c8f6 100644
--- a/include/dix.h
+++ b/include/dix.h
@@ -47,6 +47,7 @@ SOFTWARE.
 
 #ifndef DIX_H
 #define DIX_H
+#include <setjmp.h>
 
 #include "gc.h"
 #include "window.h"
@@ -305,6 +306,9 @@ extern void InitAtoms(void);
 
 /* main.c */
 
+/* Environment for siglongjmp. Will be set up in main(). */
+extern sigjmp_buf sigjmp_env;
+
 extern void SetVendorRelease(int release);
 
 extern void SetVendorString(char *string);
-- 
1.5.3