This fixes issues with the server choking when it's listening to acpid and
acpid is shut down. See https://bugs.freedesktop.org/show_bug.cgi?id=5140
and http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=345537. 

This patch by Mattia Dongili.

Index: xc/programs/Xserver/hw/xfree86/os-support/linux/lnx_acpi.c
===================================================================
RCS file: /cvs/xorg/xc/programs/Xserver/hw/xfree86/os-support/linux/lnx_acpi.c,v
retrieving revision 1.2
diff -u -r1.2 lnx_acpi.c
--- xc/programs/Xserver/hw/xfree86/os-support/linux/lnx_acpi.c	31 Oct 2005 05:45:40 -0000	1.2
+++ xc/programs/Xserver/hw/xfree86/os-support/linux/lnx_acpi.c	2 Jan 2006 17:17:29 -0000
@@ -45,6 +45,13 @@
     memset(ev, 0, LINE_LENGTH);
 
     n = read( fd, ev, LINE_LENGTH );
+    if (n <= 0) {
+	/* can only happen when reading from acpid socket */
+	xf86MsgVerb(X_WARNING,3,"ACPI Event handler disappeared, reopening.\n");
+	lnxCloseACPI();
+	lnxACPIOpen();
+	return 0;
+    }
 
     /* Check that we have a video event */
     if (strstr(ev, "video") == ev) {
@@ -160,6 +167,9 @@
 #ifdef DEBUG
    ErrorF("ACPI: Closing device\n");
 #endif
+    xf86PMGetEventFromOs = NULL;
+    xf86PMConfirmEventToOs = NULL;
+
     if (ACPIihPtr) {
 	fd = xf86RemoveInputHandler(ACPIihPtr);
 	shutdown(fd, 2);