X server used to crash after XF86VidModeSwitchToMode() failure,
because of unconditional currentMode info destruction.

E.g. (the case I investigated) when screen resolution set by RandR was
lower than requested by XF86VidModeSwitchToMode(), xf86SwitchMode is
unsuccessful; due to currentMode == NULL (in some way) DRIAdjustFrame()
called itself recursively again and again, leading to stack overflow.

This patch seems to avoid the crash.

--- XFree86-4.3.0/xc/programs/Xserver/hw/xfree86/common/xf86VidMode.c.orig	Tue Jan 28 21:52:28 2003
+++ XFree86-4.3.0/xc/programs/Xserver/hw/xfree86/common/xf86VidMode.c	Sat Mar  8 01:05:00 2003
@@ -330,6 +330,8 @@
 VidModeSwitchMode(int scrnIndex, pointer mode)
 {
     ScrnInfoPtr pScrn;
+    DisplayModePtr pTmpMode;
+    Bool retval;
 
     DEBUG_P("VidModeSwitchMode");
 
@@ -338,8 +340,12 @@
 
     pScrn = xf86Screens[scrnIndex];
     /* Force a mode switch */
+    pTmpMode = pScrn->currentMode;
     pScrn->currentMode = NULL;
-    return xf86SwitchMode(pScrn->pScreen, mode);
+    retval = xf86SwitchMode(pScrn->pScreen, mode);
+    if (retval == FALSE)
+	pScrn->currentMode = pTmpMode;
+    return retval;
 }
 
 Bool