Reset only what the protocol requires, instead of full regeneration.no-regen

It's difficult to get regeneration correct in all the drivers,
extensions, and everywhere else it's currently required--and there's no
significant advantage to doing full regeneration. So instead, make DIX
reset exactly the things required by the protocol specification, and set
serverGeneration to a constant 1.

Eliminating all the ugly code that's conditional on serverGeneration is
left as a later exercise. This patch should simply improve reliability
when the server resets.

Signed-off-by: Jamey Sharp <jamey@minilop.net>

12 files changed, 298 insertions, 179 deletions

diff --git a/dix/atom.c b/dix/atom.c
index 88b40db65..5eb1d55c4 100644
--- a/dix/atom.c
+++ b/dix/atom.c
@@ -68,6 +68,7 @@ typedef struct _Node {
 } NodeRec, *NodePtr;
 
 static Atom lastAtom = None;
+static Atom lastServerAtom = None;
 static NodePtr atomRoot = NULL;
 static unsigned long tableLength;
 static NodePtr *nodeTable;
@@ -201,6 +202,7 @@ FreeAllAtoms(void)
     free(nodeTable);
     nodeTable = NULL;
     lastAtom = None;
+    lastServerAtom = None;
 }
 
 void
@@ -216,3 +218,31 @@ InitAtoms(void)
     if (lastAtom != XA_LAST_PREDEFINED)
 	AtomError();
 }
+
+void
+SaveServerAtoms(void)
+{
+    lastServerAtom = lastAtom;
+}
+
+static void
+ResetAtom(NodePtr *patom)
+{
+    if (!*patom)
+	return;
+    if ((*patom)->a > lastServerAtom)
+    {
+	FreeAtom(*patom);
+	*patom = NULL;
+	return;
+    }
+    ResetAtom(&(*patom)->left);
+    ResetAtom(&(*patom)->right);
+}
+
+void
+ResetAtoms(void)
+{
+    lastAtom = lastServerAtom;
+    ResetAtom(&atomRoot);
+}
diff --git a/dix/devices.c b/dix/devices.c
index da817a8af..7d91416a1 100644
--- a/dix/devices.c
+++ b/dix/devices.c
@@ -2645,3 +2645,25 @@ void valuator_set_mode(DeviceIntPtr dev, int axis, int mode)
             dev->valuator->axes[i].mode = mode;
     }
 }
+
+void ResetInput(void)
+{
+    BITS32 mask = KBKeyClickPercent | KBBellPercent | KBBellPitch | KBBellDuration | KBAutoRepeatMode;
+    XID attrs[] = { -1, -1, -1, -1, AutoRepeatModeDefault };
+    DeviceIntPtr dev;
+    for (dev = inputInfo.devices; dev; dev = dev->next)
+    {
+	/* TODO: reset keyboard and pointer mappings */
+	if (dev->focus)
+	{
+	    dev->focus->win = PointerRootWin;
+	    dev->focus->revert = None;
+	    dev->focus->time = currentTime;
+	    dev->focus->traceGood = 0;
+	}
+	if (dev->kbdfeed)
+	    DoChangeKeyboardControl(serverClient, dev, attrs, mask);
+	if (dev->ptrfeed)
+	    dev->ptrfeed->ctrl = defaultPointerControl;
+    }
+}
diff --git a/dix/globals.c b/dix/globals.c
index 0a6b17085..28f9dbd12 100644
--- a/dix/globals.c
+++ b/dix/globals.c
@@ -84,7 +84,6 @@ int  currentMaxClients;   /* current size of clients array */
 long maxBigRequestSize = MAX_BIG_REQUEST_SIZE;
 
 unsigned long globalSerialNumber = 0;
-unsigned long serverGeneration = 0;
 
 /* these next four are initialized in main.c */
 CARD32 ScreenSaverTime;
diff --git a/dix/main.c b/dix/main.c
index 16575ceba..745fe050a 100644
--- a/dix/main.c
+++ b/dix/main.c
@@ -132,7 +132,7 @@ int dix_main(int argc, char *argv[], char *envp[])
 int main(int argc, char *argv[], char *envp[])
 #endif
 {
-    int		i;
+    int			i;
     HWEventQueueType	alwaysCheckForInput[2];
 
     display = "0";
@@ -149,211 +149,239 @@ int main(int argc, char *argv[], char *envp[])
 
     alwaysCheckForInput[0] = 0;
     alwaysCheckForInput[1] = 1;
-    while(1)
-    {
-	serverGeneration++;
-	ScreenSaverTime = defaultScreenSaverTime;
-	ScreenSaverInterval = defaultScreenSaverInterval;
-	ScreenSaverBlanking = defaultScreenSaverBlanking;
-	ScreenSaverAllowExposures = defaultScreenSaverAllowExposures;
+
+    ScreenSaverTime = defaultScreenSaverTime;
+    ScreenSaverInterval = defaultScreenSaverInterval;
+    ScreenSaverBlanking = defaultScreenSaverBlanking;
+    ScreenSaverAllowExposures = defaultScreenSaverAllowExposures;
 #ifdef DPMSExtension
-	DPMSStandbyTime = DPMSSuspendTime = DPMSOffTime = ScreenSaverTime;
-	DPMSEnabled = TRUE;
-	DPMSPowerLevel = 0;
+    DPMSStandbyTime = DPMSSuspendTime = DPMSOffTime = ScreenSaverTime;
+    DPMSEnabled = TRUE;
+    DPMSPowerLevel = 0;
 #endif
-	InitBlockAndWakeupHandlers();
-	/* Perform any operating system dependent initializations you'd like */
-	OsInit();
-	if(serverGeneration == 1)
-	{
-	    CreateWellKnownSockets();
-	    for (i=1; i<MAXCLIENTS; i++)
-		clients[i] = NullClient;
-	    serverClient = calloc(sizeof(ClientRec), 1);
-	    if (!serverClient)
-		FatalError("couldn't create server client");
-	    InitClient(serverClient, 0, (pointer)NULL);
-	}
-	else
-	    ResetWellKnownSockets ();
-	clients[0] = serverClient;
-	currentMaxClients = 1;
-
-	/* Initialize privates before first allocation */
-	dixResetPrivates();
-
-	/* Initialize server client devPrivates, to be reallocated as
-	 * more client privates are registered
-	 */
-	if (!dixAllocatePrivates(&serverClient->devPrivates, PRIVATE_CLIENT))
-	    FatalError("failed to create server client privates");
-
-	if (!InitClientResources(serverClient))      /* for root resources */
-	    FatalError("couldn't init server resources");
-
-	SetInputCheck(&alwaysCheckForInput[0], &alwaysCheckForInput[1]);
-	screenInfo.numScreens = 0;
-
-	InitAtoms();
-	InitEvents();
-	InitSelections();
-	InitGlyphCaching();
-	dixResetRegistry();
-	ResetFontPrivateIndex();
-	InitCallbackManager();
-	InitOutput(&screenInfo, argc, argv);
-
-	if (screenInfo.numScreens < 1)
-	    FatalError("no screens found");
-	InitExtensions(argc, argv);
-
-	for (i = 0; i < screenInfo.numScreens; i++)
-	{
-	    ScreenPtr pScreen = screenInfo.screens[i];
-	    if (!CreateScratchPixmapsForScreen(i))
-		FatalError("failed to create scratch pixmaps");
-	    if (pScreen->CreateScreenResources &&
-		!(*pScreen->CreateScreenResources)(pScreen))
-		FatalError("failed to create screen resources");
-	    if (!CreateGCperDepth(i))
-		FatalError("failed to create scratch GCs");
-	    if (!CreateDefaultStipple(i))
-		FatalError("failed to create default stipple");
-	    if (!CreateRootWindow(pScreen))
-		FatalError("failed to create root window");
-	}
-
-	InitFonts();
-	if (SetDefaultFontPath(defaultFontPath) != Success) {
-	    ErrorF("[dix] failed to set default font path '%s'", defaultFontPath);
-	}
-	if (!SetDefaultFont(defaultTextFont)) {
-	    FatalError("could not open default font '%s'", defaultTextFont);
-	}
-
-	if (!(rootCursor = CreateRootCursor(NULL, 0))) {
-	    FatalError("could not open default cursor font '%s'",
-		       defaultCursorFont);
-	}
+    InitBlockAndWakeupHandlers();
+    /* Perform any operating system dependent initializations you'd like */
+    OsInit();
+    CreateWellKnownSockets();
+
+    for (i=1; i<MAXCLIENTS; i++)
+        clients[i] = NullClient;
+    serverClient = calloc(sizeof(ClientRec), 1);
+    if (!serverClient)
+        FatalError("couldn't create server client");
+    InitClient(serverClient, 0, (pointer)NULL);
+    clients[0] = serverClient;
+    currentMaxClients = 1;
+
+    /* Initialize privates before first allocation */
+    dixResetPrivates();
+
+    /* Initialize server client devPrivates, to be reallocated as
+     * more client privates are registered
+     */
+    if (!dixAllocatePrivates(&serverClient->devPrivates, PRIVATE_CLIENT))
+        FatalError("failed to create server client privates");
+
+    if (!InitClientResources(serverClient))      /* for root resources */
+        FatalError("couldn't init server resources");
+
+    SetInputCheck(&alwaysCheckForInput[0], &alwaysCheckForInput[1]);
+    screenInfo.numScreens = 0;
+
+    InitAtoms();
+    InitEvents();
+    InitSelections();
+    InitGlyphCaching();
+    dixResetRegistry();
+    ResetFontPrivateIndex();
+    InitCallbackManager();
+    InitOutput(&screenInfo, argc, argv);
+
+    if (screenInfo.numScreens < 1)
+        FatalError("no screens found");
+    InitExtensions(argc, argv);
+
+    for (i = 0; i < screenInfo.numScreens; i++)
+    {
+        ScreenPtr pScreen = screenInfo.screens[i];
+        if (!CreateScratchPixmapsForScreen(i))
+            FatalError("failed to create scratch pixmaps");
+        if (pScreen->CreateScreenResources &&
+                !(*pScreen->CreateScreenResources)(pScreen))
+            FatalError("failed to create screen resources");
+        if (!CreateGCperDepth(i))
+            FatalError("failed to create scratch GCs");
+        if (!CreateDefaultStipple(i))
+            FatalError("failed to create default stipple");
+        if (!CreateRootWindow(pScreen))
+            FatalError("failed to create root window");
+    }
+
+    InitFonts();
+    if (SetDefaultFontPath(defaultFontPath) != Success) {
+        ErrorF("[dix] failed to set default font path '%s'", defaultFontPath);
+    }
+    if (!SetDefaultFont(defaultTextFont)) {
+        FatalError("could not open default font '%s'", defaultTextFont);
+    }
+
+    if (!(rootCursor = CreateRootCursor(NULL, 0))) {
+        FatalError("could not open default cursor font '%s'",
+                defaultCursorFont);
+    }
 
 #ifdef DPMSExtension
- 	/* check all screens, looking for DPMS Capabilities */
- 	DPMSCapableFlag = DPMSSupported();
-	if (!DPMSCapableFlag)
-     	    DPMSEnabled = FALSE;
+    /* check all screens, looking for DPMS Capabilities */
+    DPMSCapableFlag = DPMSSupported();
+    if (!DPMSCapableFlag)
+        DPMSEnabled = FALSE;
 #endif
 
 #ifdef PANORAMIX
-	/*
-	 * Consolidate window and colourmap information for each screen
-	 */
-	if (!noPanoramiXExtension)
-	    PanoramiXConsolidate();
+    /*
+     * Consolidate window and colourmap information for each screen
+     */
+    if (!noPanoramiXExtension)
+        PanoramiXConsolidate();
 #endif
 
-	for (i = 0; i < screenInfo.numScreens; i++)
-	    InitRootWindow(screenInfo.screens[i]->root);
+    for (i = 0; i < screenInfo.numScreens; i++)
+        InitRootWindow(screenInfo.screens[i]->root);
 
-        InitCoreDevices();
-	InitInput(argc, argv);
-	InitAndStartDevices();
-	ReserveClientIds(serverClient);
+    InitCoreDevices();
+    InitInput(argc, argv);
+    InitAndStartDevices();
+    ReserveClientIds(serverClient);
 
-	dixSaveScreens(serverClient, SCREEN_SAVER_FORCER, ScreenSaverReset);
+    dixSaveScreens(serverClient, SCREEN_SAVER_FORCER, ScreenSaverReset);
 
 #ifdef PANORAMIX
-	if (!noPanoramiXExtension) {
-	    if (!PanoramiXCreateConnectionBlock()) {
-		FatalError("could not create connection block info");
-	    }
-	} else
-#endif
-	{
-	    if (!CreateConnectionBlock()) {
-	    	FatalError("could not create connection block info");
-	    }
-	}
-
-#ifdef XQUARTZ
-	/* Let the other threads know the server is done with its init */
-	pthread_mutex_lock(&serverRunningMutex);
-	serverRunning = TRUE;
-	pthread_cond_broadcast(&serverRunningCond);
-	pthread_mutex_unlock(&serverRunningMutex);
+    if (!noPanoramiXExtension) {
+        if (!PanoramiXCreateConnectionBlock()) {
+            FatalError("could not create connection block info");
+        }
+    } else
 #endif
-        
-	NotifyParentProcess();
+    {
+        if (!CreateConnectionBlock()) {
+            FatalError("could not create connection block info");
+        }
+    }
 
-	Dispatch();
+    SaveServerAtoms();
 
 #ifdef XQUARTZ
-	/* Let the other threads know the server is no longer running */
-	pthread_mutex_lock(&serverRunningMutex);
-	serverRunning = FALSE;
-	pthread_mutex_unlock(&serverRunningMutex);
+    /* Let the other threads know the server is done with its init */
+    pthread_mutex_lock(&serverRunningMutex);
+    serverRunning = TRUE;
+    pthread_cond_broadcast(&serverRunningCond);
+    pthread_mutex_unlock(&serverRunningMutex);
 #endif
 
-	UndisplayDevices();
-
-	/* Now free up whatever must be freed */
-	if (screenIsSaved == SCREEN_SAVER_ON)
-	    dixSaveScreens(serverClient, SCREEN_SAVER_OFF, ScreenSaverReset);
-	FreeScreenSaverTimer();
-	CloseDownExtensions();
+    NotifyParentProcess();
 
+    while ((dispatchException & DE_TERMINATE) == 0)
+    {
+        Dispatch();
+
+        /* As specified in "X Window System Protocol" chapter 10,
+         * "Connection Close":
+         *
+         * At every transition to the state of having no connections as
+         * a result of a connection closing with a Destroy close-down
+         * mode, the server resets its state as if it had just been
+         * started. */
+
+        /* - This starts by destroying all lingering resources from
+         *   clients that have terminated in RetainPermanent or
+         *   RetainTemporary mode. */
 #ifdef PANORAMIX
-	{
-	    Bool remember_it = noPanoramiXExtension;
-	    noPanoramiXExtension = TRUE;
-	    FreeAllResources();
-	    noPanoramiXExtension = remember_it;
-	}
+        {
+            Bool remember_it = noPanoramiXExtension;
+            noPanoramiXExtension = TRUE;
+            FreeAllResources();
+            noPanoramiXExtension = remember_it;
+        }
 #else
-	FreeAllResources();
+        FreeAllResources();
 #endif
 
-        CloseInput();
+        /* - It additionally includes deleting all but the predefined
+         *   atom identifiers, */
+        ResetAtoms();
+
+        for (i = 0; i < screenInfo.numScreens; i++)
+        {
+            /* - deleting all properties on all root windows, */
+            ResetProperties(screenInfo.screens[i]->root);
+
+            /* - restoring the standard root tiles and cursors, */
+            ResetRootWindow(screenInfo.screens[i]->root);
+        }
+
+        /* - resetting the access control list, */
+        ResetWellKnownSockets();
 
-	for (i = 0; i < screenInfo.numScreens; i++)
-	    screenInfo.screens[i]->root = NullWindow;
-	CloseDownDevices();
-	CloseDownEvents();
+        /* - restoring the default font path, */
+        if (SetDefaultFontPath(defaultFontPath) != Success)
+            ErrorF("[dix] failed to set default font path '%s'", defaultFontPath);
 
-	for (i = screenInfo.numScreens - 1; i >= 0; i--)
-	{
-	    FreeScratchPixmapsForScreen(i);
-	    FreeGCperDepth(i);
-	    FreeDefaultStipple(i);
-	    (* screenInfo.screens[i]->CloseScreen)(i, screenInfo.screens[i]);
-	    dixFreePrivates(screenInfo.screens[i]->devPrivates, PRIVATE_SCREEN);
-	    free(screenInfo.screens[i]);
-	    screenInfo.numScreens = i;
-	}
+        /* - resetting all device maps and attributes (key click, bell
+         *   volume, acceleration),
+         * - and restoring the input focus to state PointerRoot. */
+        ResetInput();
+    }
 
-	ReleaseClientIds(serverClient);
-	dixFreePrivates(serverClient->devPrivates, PRIVATE_CLIENT);
-	serverClient->devPrivates = NULL;
+#ifdef XQUARTZ
+    /* Let the other threads know the server is no longer running */
+    pthread_mutex_lock(&serverRunningMutex);
+    serverRunning = FALSE;
+    pthread_mutex_unlock(&serverRunningMutex);
+#endif
 
-	FreeFonts();
+    UndisplayDevices();
 
-	FreeAuditTimer();
+    /* Now free up whatever must be freed */
+    if (screenIsSaved == SCREEN_SAVER_ON)
+        dixSaveScreens(serverClient, SCREEN_SAVER_OFF, ScreenSaverReset);
+    FreeScreenSaverTimer();
+    CloseDownExtensions();
 
-	if (dispatchException & DE_TERMINATE)
-	{
-	    CloseWellKnownConnections();
-	}
+    FreeClientResources(serverClient);
 
-	OsCleanup((dispatchException & DE_TERMINATE) != 0);
+    CloseInput();
 
-	if (dispatchException & DE_TERMINATE)
-	{
-	    ddxGiveUp(EXIT_NO_ERROR);
-	    break;
-	}
+    for (i = 0; i < screenInfo.numScreens; i++)
+        screenInfo.screens[i]->root = NullWindow;
+    CloseDownDevices();
+    CloseDownEvents();
 
-	free(ConnectionInfo);
-	ConnectionInfo = NULL;
+    for (i = screenInfo.numScreens - 1; i >= 0; i--)
+    {
+        FreeScratchPixmapsForScreen(i);
+        FreeGCperDepth(i);
+        FreeDefaultStipple(i);
+        (* screenInfo.screens[i]->CloseScreen)(i, screenInfo.screens[i]);
+        dixFreePrivates(screenInfo.screens[i]->devPrivates, PRIVATE_SCREEN);
+        free(screenInfo.screens[i]);
+        screenInfo.numScreens = i;
     }
+
+    ReleaseClientIds(serverClient);
+    dixFreePrivates(serverClient->devPrivates, PRIVATE_CLIENT);
+    serverClient->devPrivates = NULL;
+
+    FreeFonts();
+
+    FreeAuditTimer();
+
+    CloseWellKnownConnections();
+
+    OsCleanup(TRUE);
+
+    free(ConnectionInfo);
+
+    ddxGiveUp(EXIT_NO_ERROR);
     return 0;
 }
 
diff --git a/dix/property.c b/dix/property.c
index a1ae5305d..87b8fe3c6 100644
--- a/dix/property.c
+++ b/dix/property.c
@@ -284,6 +284,7 @@ dixChangeWindowProperty(ClientPtr pClient, WindowPtr pWin, Atom property,
         pProp->format = format;
         pProp->data = data;
 	pProp->size = len;
+	pProp->retain = (pClient == serverClient);
 	rc = XaceHookPropertyAccess(pClient, pWin, &pProp,
 				    DixCreateAccess|DixWriteAccess);
 	if (rc != Success) {
@@ -429,6 +430,26 @@ DeleteAllWindowProperties(WindowPtr pWin)
         pWin->optional->userProps = NULL;
 }
 
+void
+ResetProperties(WindowPtr pWin)
+{
+    PropertyPtr tmp, *pProp;
+    if (!pWin->optional)
+	return;
+
+    for (pProp = &pWin->optional->userProps; (tmp = *pProp); )
+    {
+	if (tmp->retain && ValidAtom(tmp->propertyName) && ValidAtom(tmp->type))
+	{
+	    pProp = &tmp->next;
+	    continue;
+	}
+	*pProp = tmp->next;
+	free(tmp->data);
+	dixFreeObjectWithPrivates(tmp, PRIVATE_PROPERTY);
+    }
+}
+
 static int
 NullPropertyReply(
     ClientPtr client,
diff --git a/dix/resource.c b/dix/resource.c
index eb9f0492a..efe196459 100644
--- a/dix/resource.c
+++ b/dix/resource.c
@@ -863,7 +863,8 @@ FreeAllResources(void)
 {
     int	i;
 
-    for (i = currentMaxClients; --i >= 0; ) 
+    /* don't free serverClient's resources */
+    for (i = currentMaxClients; --i > 0; )
     {
         if (clientTable[i].buckets) 
 	    FreeClientResources(clients[i]);
diff --git a/dix/window.c b/dix/window.c
index c87020dff..987bb3327 100644
--- a/dix/window.c
+++ b/dix/window.c
@@ -543,16 +543,21 @@ void
 InitRootWindow(WindowPtr pWin)
 {
     ScreenPtr pScreen = pWin->drawable.pScreen;
-    int mask = CWBackPixmap | CWBackingStore | CWCursor;
-    XID attrs[] = { None, defaultBackingStore, None };
-
     if (!(*pScreen->CreateWindow)(pWin))
 	return; /* XXX */
     (*pScreen->PositionWindow)(pWin, 0, 0);
-    ChangeWindowAttributes(pWin, mask, attrs, serverClient);
+    ResetRootWindow(pWin);
     MapWindow(pWin, serverClient);
 }
 
+void
+ResetRootWindow(WindowPtr pWin)
+{
+    int mask = CWBackPixmap | CWBackingStore | CWCursor;
+    XID attrs[] = { None, defaultBackingStore, None };
+    ChangeWindowAttributes(pWin, mask, attrs, serverClient);
+}
+
 /* Set the region to the intersection of the rectangle and the
  * window's winSize.  The window is typically the parent of the
  * window from which the region came.
diff --git a/include/dix.h b/include/dix.h
index 34661f3b6..7a931c3ac 100644
--- a/include/dix.h
+++ b/include/dix.h
@@ -306,12 +306,19 @@ extern _X_EXPORT void FreeAllAtoms(void);
 
 extern _X_EXPORT void InitAtoms(void);
 
+extern void SaveServerAtoms(void);
+extern void ResetAtoms(void);
+
 /* main.c */
 
 extern _X_EXPORT void SetVendorRelease(int release);
 
 extern _X_EXPORT void SetVendorString(char *string);
 
+/* devices.c */
+
+extern void ResetInput(void);
+
 /* events.c */
 
 extern void SetMaskForEvent(
diff --git a/include/misc.h b/include/misc.h
index dc039113d..10970506f 100644
--- a/include/misc.h
+++ b/include/misc.h
@@ -357,6 +357,6 @@ typedef struct _CharInfo *CharInfoPtr; /* also in fonts/include/font.h */
 #endif
 
 extern _X_EXPORT unsigned long globalSerialNumber;
-extern _X_EXPORT unsigned long serverGeneration;
+#define serverGeneration 1
 
 #endif /* MISC_H */
diff --git a/include/property.h b/include/property.h
index 075eb4a0d..01379ed11 100644
--- a/include/property.h
+++ b/include/property.h
@@ -88,4 +88,6 @@ extern _X_EXPORT int DeleteProperty(
 extern _X_EXPORT void DeleteAllWindowProperties(
     WindowPtr /*pWin*/);
 
+extern void ResetProperties(WindowPtr /*pWin*/);
+
 #endif  /* PROPERTY_H */
diff --git a/include/propertyst.h b/include/propertyst.h
index 1edd11d5d..73ccce65d 100644
--- a/include/propertyst.h
+++ b/include/propertyst.h
@@ -61,6 +61,7 @@ typedef struct _Property {
 	uint32_t	format;     /* format of data for swapping - 8,16,32 */
 	uint32_t	size;       /* size of data in (format/8) bytes */
 	pointer         data;       /* private to client */
+	unsigned int	retain : 1; /* should this property be retained across server reset? */
 	PrivateRec	*devPrivates;
 } PropertyRec;
 
diff --git a/include/window.h b/include/window.h
index e13598b88..1bb51e7ce 100644
--- a/include/window.h
+++ b/include/window.h
@@ -93,6 +93,9 @@ extern _X_EXPORT Bool CreateRootWindow(
 extern _X_EXPORT void InitRootWindow(
     WindowPtr /*pWin*/);
 
+extern void ResetRootWindow(
+    WindowPtr /*pWin*/);
+
 typedef WindowPtr (* RealChildHeadProc) (WindowPtr pWin);
 
 extern _X_EXPORT void RegisterRealChildHeadProc (RealChildHeadProc proc);