/*

  * tclUnixNotify.c --

  *

  *	This file contains the implementation of the select-based

  *	Unix-specific notifier, which is the lowest-level part of the

  *	Tcl event loop.  This file works together with

  *	../generic/tclNotify.c.

  *

  * Copyright (c) 1995-1997 Sun Microsystems, Inc.

  * Portions Copyright (c) 2007-2008 Nokia Corporation and/or its subsidiaries. All rights reserved.  

  *

  * See the file "license.terms" for information on usage and redistribution

  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.

  *

  * RCS: @(#) $Id: tclUnixNotfy.c,v 1.11.2.16 2006/08/22 17:45:02 andreas_kupries Exp $

  */

 #include "tclInt.h"

 #include "tclPort.h"

 #if defined(__SYMBIAN32__) && defined(__WINSCW__)

 #include "tclSymbianGlobals.h"

 #define dataKey getdataKey(8)

 #endif 

 #ifndef HAVE_COREFOUNDATION /* Darwin/Mac OS X CoreFoundation notifier

                              * is in tclMacOSXNotify.c */

 #ifndef __SYMBIAN32__  // added to prevent link errors on armv5

 #include <signal.h> 

 #endif

 extern TclStubs tclStubs;

 extern Tcl_NotifierProcs tclOriginalNotifier;

 /*

  * This structure is used to keep track of the notifier info for a 

  * a registered file.

  */

 typedef struct FileHandler {

     int fd;

     int mask;			/* Mask of desired events: TCL_READABLE,

 				 * etc. */

     int readyMask;		/* Mask of events that have been seen since the

 				 * last time file handlers were invoked for

 				 * this file. */

     Tcl_FileProc *proc;		/* Procedure to call, in the style of

 				 * Tcl_CreateFileHandler. */

     ClientData clientData;	/* Argument to pass to proc. */

     struct FileHandler *nextPtr;/* Next in list of all files we care about. */

 } FileHandler;

 /*

  * The following structure is what is added to the Tcl event queue when

  * file handlers are ready to fire.

  */

 typedef struct FileHandlerEvent {

     Tcl_Event header;		/* Information that is standard for

 				 * all events. */

     int fd;			/* File descriptor that is ready.  Used

 				 * to find the FileHandler structure for

 				 * the file (can't point directly to the

 				 * FileHandler structure because it could

 				 * go away while the event is queued). */

 } FileHandlerEvent;

 /*

  *

  * The following structure contains a set of select() masks to track

  * readable, writable, and exceptional conditions.

  */

 typedef struct SelectMasks {

     fd_set readable;

     fd_set writable;

     fd_set exceptional;

 } SelectMasks;

 /*

  * The following static structure contains the state information for the

  * select based implementation of the Tcl notifier.  One of these structures

  * is created for each thread that is using the notifier.  

  */

 typedef struct ThreadSpecificData {

     FileHandler *firstFileHandlerPtr;

 				/* Pointer to head of file handler list. */

     SelectMasks checkMasks;	/* This structure is used to build up the masks

 				 * to be used in the next call to select.

 				 * Bits are set in response to calls to

 				 * Tcl_CreateFileHandler. */

     SelectMasks readyMasks;	/* This array reflects the readable/writable

 				 * conditions that were found to exist by the

 				 * last call to select. */

     int numFdBits;		/* Number of valid bits in checkMasks

 				 * (one more than highest fd for which

 				 * Tcl_WatchFile has been called). */

 #ifdef TCL_THREADS

     int onList;			/* True if it is in this list */

     unsigned int pollState;	/* pollState is used to implement a polling 

 				 * handshake between each thread and the

 				 * notifier thread. Bits defined below. */

     struct ThreadSpecificData *nextPtr, *prevPtr;

                                 /* All threads that are currently waiting on 

                                  * an event have their ThreadSpecificData

                                  * structure on a doubly-linked listed formed

                                  * from these pointers.  You must hold the

                                  * notifierMutex lock before accessing these

                                  * fields. */

     Tcl_Condition waitCV;     /* Any other thread alerts a notifier

 				 * that an event is ready to be processed

 				 * by signaling this condition variable. */

     int eventReady;           /* True if an event is ready to be processed.

                                * Used as condition flag together with

                                * waitCV above. */

 #endif

 } ThreadSpecificData;

 #if !defined(__SYMBIAN32__) || !defined(__WINSCW__)

 static Tcl_ThreadDataKey dataKey;

 #endif

 #ifdef TCL_THREADS

 /*

  * The following static indicates the number of threads that have

  * initialized notifiers.

  *

  * You must hold the notifierMutex lock before accessing this variable.

  */

 static int notifierCount = 0;

 /*

  * The following variable points to the head of a doubly-linked list of 

  * of ThreadSpecificData structures for all threads that are currently

  * waiting on an event.

  *

  * You must hold the notifierMutex lock before accessing this list.

  */

 static ThreadSpecificData *waitingListPtr = NULL;

 /*

  * The notifier thread spends all its time in select() waiting for a

  * file descriptor associated with one of the threads on the waitingListPtr

  * list to do something interesting.  But if the contents of the

  * waitingListPtr list ever changes, we need to wake up and restart

  * the select() system call.  You can wake up the notifier thread by

  * writing a single byte to the file descriptor defined below.  This

  * file descriptor is the input-end of a pipe and the notifier thread is

  * listening for data on the output-end of the same pipe.  Hence writing

  * to this file descriptor will cause the select() system call to return

  * and wake up the notifier thread.

  *

  * You must hold the notifierMutex lock before accessing this list.

  */

 static int triggerPipe = -1;

 /*

  * The notifierMutex locks access to all of the global notifier state. 

  */

 TCL_DECLARE_MUTEX(notifierMutex)

 /*

  * The notifier thread signals the notifierCV when it has finished

  * initializing the triggerPipe and right before the notifier

  * thread terminates.

  */

 static Tcl_Condition notifierCV;

 /*

  * The pollState bits

  *	POLL_WANT is set by each thread before it waits on its condition

  *		variable.  It is checked by the notifier before it does

  *		select.

  *	POLL_DONE is set by the notifier if it goes into select after

  *		seeing POLL_WANT.  The idea is to ensure it tries a select

  *		with the same bits the initial thread had set.

  */

 #define POLL_WANT	0x1

 #define POLL_DONE	0x2

 /*

  * This is the thread ID of the notifier thread that does select.

  */

 static Tcl_ThreadId notifierThread;

 #endif

 /*

  * Static routines defined in this file.

  */

 #ifdef TCL_THREADS

 static void	NotifierThreadProc _ANSI_ARGS_((ClientData clientData));

 #endif

 static int	FileHandlerEventProc _ANSI_ARGS_((Tcl_Event *evPtr,

 		    int flags));

 /*

  *----------------------------------------------------------------------

  *

  * Tcl_InitNotifier --

  *

  *	Initializes the platform specific notifier state.

  *

  * Results:

  *	Returns a handle to the notifier state for this thread..

  *

  * Side effects:

  *	None.

  *

  *----------------------------------------------------------------------

  */

 EXPORT_C ClientData

 Tcl_InitNotifier()

 {

     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

 #ifdef TCL_THREADS

     tsdPtr->eventReady = 0;

     /*

      * Start the Notifier thread if necessary.

      */

     Tcl_MutexLock(&notifierMutex);

     if (notifierCount == 0) {

 	if (TclpThreadCreate(&notifierThread, NotifierThreadProc, NULL,

 		     TCL_THREAD_STACK_DEFAULT, TCL_THREAD_JOINABLE) != TCL_OK) {

 	    panic("Tcl_InitNotifier: unable to start notifier thread");

 	}

     }

     notifierCount++;

     /*

      * Wait for the notifier pipe to be created.

      */

     while (triggerPipe < 0) {

 	Tcl_ConditionWait(&notifierCV, &notifierMutex, NULL);

     }

     Tcl_MutexUnlock(&notifierMutex);

 #endif

     return (ClientData) tsdPtr;

 }

 /*

  *----------------------------------------------------------------------

  *

  * Tcl_FinalizeNotifier --

  *

  *	This function is called to cleanup the notifier state before

  *	a thread is terminated.

  *

  * Results:

  *	None.

  *

  * Side effects:

  *	May terminate the background notifier thread if this is the

  *	last notifier instance.

  *

  *----------------------------------------------------------------------

  */

 EXPORT_C void

 Tcl_FinalizeNotifier(clientData)

     ClientData clientData;		/* Not used. */

 {

 #ifdef TCL_THREADS

     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

     Tcl_MutexLock(&notifierMutex);

     notifierCount--;

     /*

      * If this is the last thread to use the notifier, close the notifier

      * pipe and wait for the background thread to terminate.

      */

     if (notifierCount == 0) {

 	int result;

 	if (triggerPipe < 0) {

 	    panic("Tcl_FinalizeNotifier: notifier pipe not initialized");

 	}

 	/*

 	 * Send "q" message to the notifier thread so that it will

 	 * terminate.  The notifier will return from its call to select()

 	 * and notice that a "q" message has arrived, it will then close

 	 * its side of the pipe and terminate its thread.  Note the we can

 	 * not just close the pipe and check for EOF in the notifier

 	 * thread because if a background child process was created with

 	 * exec, select() would not register the EOF on the pipe until the

 	 * child processes had terminated. [Bug: 4139] [Bug: 1222872]

 	 */

 	write(triggerPipe, "q", 1);

 	close(triggerPipe);

 	while(triggerPipe >= 0) {

 	    Tcl_ConditionWait(&notifierCV, &notifierMutex, NULL);

 	}

 	result = Tcl_JoinThread(notifierThread, NULL);

 	if (result) {

 	    Tcl_Panic("Tcl_FinalizeNotifier: unable to join notifier thread");

 	}

     }

     /*

      * Clean up any synchronization objects in the thread local storage.

      */

     Tcl_ConditionFinalize(&(tsdPtr->waitCV));

     Tcl_MutexUnlock(&notifierMutex);

 #endif

 }

 /*

  *----------------------------------------------------------------------

  *

  * Tcl_AlertNotifier --

  *

  *	Wake up the specified notifier from any thread. This routine

  *	is called by the platform independent notifier code whenever

  *	the Tcl_ThreadAlert routine is called.  This routine is

  *	guaranteed not to be called on a given notifier after

  *	Tcl_FinalizeNotifier is called for that notifier.

  *

  * Results:

  *	None.

  *

  * Side effects:

  *	Signals the notifier condition variable for the specified

  *	notifier.

  *

  *----------------------------------------------------------------------

  */

 EXPORT_C void

 Tcl_AlertNotifier(clientData)

     ClientData clientData;

 {

 #ifdef TCL_THREADS

     ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData;

     Tcl_MutexLock(&notifierMutex);

     tsdPtr->eventReady = 1;

     Tcl_ConditionNotify(&tsdPtr->waitCV);

     Tcl_MutexUnlock(&notifierMutex);

 #endif

 }

 /*

  *----------------------------------------------------------------------

  *

  * Tcl_SetTimer --

  *

  *	This procedure sets the current notifier timer value.  This

  *	interface is not implemented in this notifier because we are

  *	always running inside of Tcl_DoOneEvent.

  *

  * Results:

  *	None.

  *

  * Side effects:

  *	None.

  *

  *----------------------------------------------------------------------

  */

 EXPORT_C void

 Tcl_SetTimer(timePtr)

     Tcl_Time *timePtr;		/* Timeout value, may be NULL. */

 {

     /*

      * The interval timer doesn't do anything in this implementation,

      * because the only event loop is via Tcl_DoOneEvent, which passes

      * timeout values to Tcl_WaitForEvent.

      */

     if (tclStubs.tcl_SetTimer != tclOriginalNotifier.setTimerProc) {

 	tclStubs.tcl_SetTimer(timePtr);

     }

 }

 /*

  *----------------------------------------------------------------------

  *

  * Tcl_ServiceModeHook --

  *

  *	This function is invoked whenever the service mode changes.

  *

  * Results:

  *	None.

  *

  * Side effects:

  *	None.

  *

  *----------------------------------------------------------------------

  */

 EXPORT_C void

 Tcl_ServiceModeHook(mode)

     int mode;			/* Either TCL_SERVICE_ALL, or

 				 * TCL_SERVICE_NONE. */

 {

 }

 /*

  *----------------------------------------------------------------------

  *

  * Tcl_CreateFileHandler --

  *

  *	This procedure registers a file handler with the select notifier.

  *

  * Results:

  *	None.

  *

  * Side effects:

  *	Creates a new file handler structure.

  *

  *----------------------------------------------------------------------

  */

 EXPORT_C void

 Tcl_CreateFileHandler(fd, mask, proc, clientData)

     int fd;			/* Handle of stream to watch. */

     int mask;			/* OR'ed combination of TCL_READABLE,

 				 * TCL_WRITABLE, and TCL_EXCEPTION:

 				 * indicates conditions under which

 				 * proc should be called. */

     Tcl_FileProc *proc;		/* Procedure to call for each

 				 * selected event. */

     ClientData clientData;	/* Arbitrary data to pass to proc. */

 {

     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

     FileHandler *filePtr;

     if (tclStubs.tcl_CreateFileHandler != tclOriginalNotifier.createFileHandlerProc) {

 	tclStubs.tcl_CreateFileHandler(fd, mask, proc, clientData);

 	return;

     }

     for (filePtr = tsdPtr->firstFileHandlerPtr; filePtr != NULL;

 	 filePtr = filePtr->nextPtr) {

 	if (filePtr->fd == fd) {

 	    break;

 	}

     }

     if (filePtr == NULL) {

 	filePtr = (FileHandler*) ckalloc(sizeof(FileHandler));

 	filePtr->fd = fd;

 	filePtr->readyMask = 0;

 	filePtr->nextPtr = tsdPtr->firstFileHandlerPtr;

 	tsdPtr->firstFileHandlerPtr = filePtr;

     }

     filePtr->proc = proc;

     filePtr->clientData = clientData;

     filePtr->mask = mask;

     /*

      * Update the check masks for this file.

      */

     if ( mask & TCL_READABLE ) {

 	FD_SET( fd, &(tsdPtr->checkMasks.readable) );

     } else {

 	FD_CLR( fd, &(tsdPtr->checkMasks.readable) );

     }

     if ( mask & TCL_WRITABLE ) {

 	FD_SET( fd, &(tsdPtr->checkMasks.writable) );

     } else {

 	FD_CLR( fd, &(tsdPtr->checkMasks.writable) );

     }

     if ( mask & TCL_EXCEPTION ) {

 	FD_SET( fd, &(tsdPtr->checkMasks.exceptional) );

     } else {

 	FD_CLR( fd, &(tsdPtr->checkMasks.exceptional) );

     }

     if (tsdPtr->numFdBits <= fd) {

 	tsdPtr->numFdBits = fd+1;

     }

 }

 /*

  *----------------------------------------------------------------------

  *

  * Tcl_DeleteFileHandler --

  *

  *	Cancel a previously-arranged callback arrangement for

  *	a file.

  *

  * Results:

  *	None.

  *

  * Side effects:

  *	If a callback was previously registered on file, remove it.

  *

  *----------------------------------------------------------------------

  */

 EXPORT_C void

 Tcl_DeleteFileHandler(fd)

     int fd;		/* Stream id for which to remove callback procedure. */

 {

     FileHandler *filePtr, *prevPtr;

     int i;

     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

     if (tclStubs.tcl_DeleteFileHandler != tclOriginalNotifier.deleteFileHandlerProc) {

 	tclStubs.tcl_DeleteFileHandler(fd);

 	return;

     }

     /*

      * Find the entry for the given file (and return if there isn't one).

      */

     for (prevPtr = NULL, filePtr = tsdPtr->firstFileHandlerPtr; ;

 	 prevPtr = filePtr, filePtr = filePtr->nextPtr) {

 	if (filePtr == NULL) {

 	    return;

 	}

 	if (filePtr->fd == fd) {

 	    break;

 	}

     }

     /*

      * Update the check masks for this file.

      */

     if (filePtr->mask & TCL_READABLE) {

 	FD_CLR( fd, &(tsdPtr->checkMasks.readable) );

     }

     if (filePtr->mask & TCL_WRITABLE) {

 	FD_CLR( fd, &(tsdPtr->checkMasks.writable) );

     }

     if (filePtr->mask & TCL_EXCEPTION) {

 	FD_CLR( fd, &(tsdPtr->checkMasks.exceptional) );

     }

     /*

      * Find current max fd.

      */

     if (fd+1 == tsdPtr->numFdBits) {

 	tsdPtr->numFdBits = 0;

 	for (i = fd-1; i >= 0; i--) {

 	    if ( FD_ISSET( i, &(tsdPtr->checkMasks.readable) )

 		 || FD_ISSET( i, &(tsdPtr->checkMasks.writable) )

 		 || FD_ISSET( i, &(tsdPtr->checkMasks.exceptional ) ) ) {

 		tsdPtr->numFdBits = i+1;

 		break;

 	    }

 	}

     }

     /*

      * Clean up information in the callback record.

      */

     if (prevPtr == NULL) {

 	tsdPtr->firstFileHandlerPtr = filePtr->nextPtr;

     } else {

 	prevPtr->nextPtr = filePtr->nextPtr;

     }

     ckfree((char *) filePtr);

 }

 /*

  *----------------------------------------------------------------------

  *

  * FileHandlerEventProc --

  *

  *	This procedure is called by Tcl_ServiceEvent when a file event

  *	reaches the front of the event queue.  This procedure is

  *	responsible for actually handling the event by invoking the

  *	callback for the file handler.

  *

  * Results:

  *	Returns 1 if the event was handled, meaning it should be removed

  *	from the queue.  Returns 0 if the event was not handled, meaning

  *	it should stay on the queue.  The only time the event isn't

  *	handled is if the TCL_FILE_EVENTS flag bit isn't set.

  *

  * Side effects:

  *	Whatever the file handler's callback procedure does.

  *

  *----------------------------------------------------------------------

  */

 static int

 FileHandlerEventProc(evPtr, flags)

     Tcl_Event *evPtr;		/* Event to service. */

     int flags;			/* Flags that indicate what events to

 				 * handle, such as TCL_FILE_EVENTS. */

 {

     int mask;

     FileHandler *filePtr;

     FileHandlerEvent *fileEvPtr = (FileHandlerEvent *) evPtr;

     ThreadSpecificData *tsdPtr;

     if (!(flags & TCL_FILE_EVENTS)) {

 	return 0;

     }

     /*

      * Search through the file handlers to find the one whose handle matches

      * the event.  We do this rather than keeping a pointer to the file

      * handler directly in the event, so that the handler can be deleted

      * while the event is queued without leaving a dangling pointer.

      */

     tsdPtr = TCL_TSD_INIT(&dataKey);

     for (filePtr = tsdPtr->firstFileHandlerPtr; filePtr != NULL;

 	 filePtr = filePtr->nextPtr) {

 	if (filePtr->fd != fileEvPtr->fd) {

 	    continue;

 	}

 	/*

 	 * The code is tricky for two reasons:

 	 * 1. The file handler's desired events could have changed

 	 *    since the time when the event was queued, so AND the

 	 *    ready mask with the desired mask.

 	 * 2. The file could have been closed and re-opened since

 	 *    the time when the event was queued.  This is why the

 	 *    ready mask is stored in the file handler rather than

 	 *    the queued event:  it will be zeroed when a new

 	 *    file handler is created for the newly opened file.

 	 */

 	mask = filePtr->readyMask & filePtr->mask;

 	filePtr->readyMask = 0;

 	if (mask != 0) {

 	    (*filePtr->proc)(filePtr->clientData, mask);

 	}

 	break;

     }

     return 1;

 }

 /*

  *----------------------------------------------------------------------

  *

  * Tcl_WaitForEvent --

  *

  *	This function is called by Tcl_DoOneEvent to wait for new

  *	events on the message queue.  If the block time is 0, then

  *	Tcl_WaitForEvent just polls without blocking.

  *

  * Results:

  *	Returns -1 if the select would block forever, otherwise

  *	returns 0.

  *

  * Side effects:

  *	Queues file events that are detected by the select.

  *

  *----------------------------------------------------------------------

  */

 EXPORT_C int

 Tcl_WaitForEvent(timePtr)

     Tcl_Time *timePtr;		/* Maximum block time, or NULL. */

 {

     FileHandler *filePtr;

     FileHandlerEvent *fileEvPtr;

     int mask;

 #ifdef TCL_THREADS

     int waitForFiles;

 #else

     /* Impl. notes: timeout & timeoutPtr are used if, and only if

      * threads are not enabled. They are the arguments for the regular

      * select() used when the core is not thread-enabled. */

     struct timeval timeout, *timeoutPtr;

     int numFound;

 #endif

     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

     if (tclStubs.tcl_WaitForEvent != tclOriginalNotifier.waitForEventProc) {

 	return tclStubs.tcl_WaitForEvent(timePtr);

     }

 #ifndef TCL_THREADS

     /*

      * Set up the timeout structure.  Note that if there are no events to

      * check for, we return with a negative result rather than blocking

      * forever.

      */

     if (timePtr) {

 	timeout.tv_sec = timePtr->sec;

 	timeout.tv_usec = timePtr->usec;

 	timeoutPtr = &timeout;

     } else if (tsdPtr->numFdBits == 0) {

 	/*

 	 * If there are no threads, no timeout, and no fds registered,

 	 * then there are no events possible and we must avoid deadlock.

 	 * Note that this is not entirely correct because there might

 	 * be a signal that could interrupt the select call, but we

 	 * don't handle that case if we aren't using threads.

 	 */

 	return -1;

     } else {

 	timeoutPtr = NULL;

     }

 #endif

 #ifdef TCL_THREADS

     /*

      * Place this thread on the list of interested threads, signal the

      * notifier thread, and wait for a response or a timeout.

      */

     Tcl_MutexLock(&notifierMutex);

     waitForFiles = (tsdPtr->numFdBits > 0);

     if (timePtr != NULL && timePtr->sec == 0 && (timePtr->usec == 0

 #if defined(__APPLE__) && defined(__LP64__)

 	    /*

 	     * On 64-bit Darwin, pthread_cond_timedwait() appears to have a bug

 	     * that causes it to wait forever when passed an absolute time which

 	     * has already been exceeded by the system time; as a workaround,

 	     * when given a very brief timeout, just do a poll. [Bug 1457797]

 	     */

 	    || timePtr->usec < 10

 #endif

 	    )) {

 	/*

 	 * Cannot emulate a polling select with a polling condition variable.

 	 * Instead, pretend to wait for files and tell the notifier

 	 * thread what we are doing.  The notifier thread makes sure

 	 * it goes through select with its select mask in the same state

 	 * as ours currently is.  We block until that happens.

 	 */

 	waitForFiles = 1;

 	tsdPtr->pollState = POLL_WANT;

 	timePtr = NULL;

     } else {

 	tsdPtr->pollState = 0;

     }

     if (waitForFiles) {

         /*

          * Add the ThreadSpecificData structure of this thread to the list

          * of ThreadSpecificData structures of all threads that are waiting

          * on file events.

          */

         tsdPtr->nextPtr = waitingListPtr;

         if (waitingListPtr) {

             waitingListPtr->prevPtr = tsdPtr;

         }

         tsdPtr->prevPtr = 0;

         waitingListPtr = tsdPtr;

 	tsdPtr->onList = 1;

 	write(triggerPipe, "", 1);

     }

     FD_ZERO( &(tsdPtr->readyMasks.readable) );

     FD_ZERO( &(tsdPtr->readyMasks.writable) );

     FD_ZERO( &(tsdPtr->readyMasks.exceptional) );

     if (!tsdPtr->eventReady) {

         Tcl_ConditionWait(&tsdPtr->waitCV, &notifierMutex, timePtr);

     }

     tsdPtr->eventReady = 0;

     if (waitForFiles && tsdPtr->onList) {

 	/*

 	 * Remove the ThreadSpecificData structure of this thread from the

 	 * waiting list.  Alert the notifier thread to recompute its select

 	 * masks - skipping this caused a hang when trying to close a pipe

 	 * which the notifier thread was still doing a select on.

 	 */

         if (tsdPtr->prevPtr) {

             tsdPtr->prevPtr->nextPtr = tsdPtr->nextPtr;

         } else {

             waitingListPtr = tsdPtr->nextPtr;

         }

         if (tsdPtr->nextPtr) {

             tsdPtr->nextPtr->prevPtr = tsdPtr->prevPtr;

         }

         tsdPtr->nextPtr = tsdPtr->prevPtr = NULL;

 	tsdPtr->onList = 0;

 	write(triggerPipe, "", 1);

     }

 #else

     tsdPtr->readyMasks = tsdPtr->checkMasks;

     numFound = select( tsdPtr->numFdBits,

 		       &(tsdPtr->readyMasks.readable),

 		       &(tsdPtr->readyMasks.writable),

 		       &(tsdPtr->readyMasks.exceptional),

 		       timeoutPtr );

     /*

      * Some systems don't clear the masks after an error, so

      * we have to do it here.

      */

     if (numFound == -1) {

 	FD_ZERO( &(tsdPtr->readyMasks.readable ) );

 	FD_ZERO( &(tsdPtr->readyMasks.writable ) );

 	FD_ZERO( &(tsdPtr->readyMasks.exceptional ) );

     }

 #endif

     /*

      * Queue all detected file events before returning.

      */

     for (filePtr = tsdPtr->firstFileHandlerPtr; (filePtr != NULL);

 	 filePtr = filePtr->nextPtr) {

 	mask = 0;

 	if ( FD_ISSET( filePtr->fd, &(tsdPtr->readyMasks.readable) ) ) {

 	    mask |= TCL_READABLE;

 	}

 	if ( FD_ISSET( filePtr->fd, &(tsdPtr->readyMasks.writable) ) ) {

 	    mask |= TCL_WRITABLE;

 	}

 	if ( FD_ISSET( filePtr->fd, &(tsdPtr->readyMasks.exceptional) ) ) {

 	    mask |= TCL_EXCEPTION;

 	}

 	if (!mask) {

 	    continue;

 	}

 	/*

 	 * Don't bother to queue an event if the mask was previously

 	 * non-zero since an event must still be on the queue.

 	 */

 	if (filePtr->readyMask == 0) {

 	    fileEvPtr = (FileHandlerEvent *) ckalloc(

 		sizeof(FileHandlerEvent));

 	    fileEvPtr->header.proc = FileHandlerEventProc;

 	    fileEvPtr->fd = filePtr->fd;

 	    Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL);

 	}

 	filePtr->readyMask = mask;

     }

 #ifdef TCL_THREADS

     Tcl_MutexUnlock(&notifierMutex);

 #endif

     return 0;

 }

 #ifdef TCL_THREADS

 /*

  *----------------------------------------------------------------------

  *

  * NotifierThreadProc --

  *

  *	This routine is the initial (and only) function executed by the

  *	special notifier thread.  Its job is to wait for file descriptors

  *	to become readable or writable or to have an exception condition

  *	and then to notify other threads who are interested in this

  *	information by signalling a condition variable.  Other threads

  *	can signal this notifier thread of a change in their interests

  *	by writing a single byte to a special pipe that the notifier

  *	thread is monitoring.

  *

  * Result:

  *	None.  Once started, this routine never exits.  It dies with

  *	the overall process.

  *

  * Side effects:

  *	The trigger pipe used to signal the notifier thread is created

  *	when the notifier thread first starts.

  *

  *----------------------------------------------------------------------

  */

 static void

 NotifierThreadProc(clientData)

     ClientData clientData;	/* Not used. */

 {

     ThreadSpecificData *tsdPtr;

     fd_set readableMask;

     fd_set writableMask;

     fd_set exceptionalMask;

     int fds[2];

     int i, status, numFdBits = 0, receivePipe;

     long found;

     struct timeval poll = {0., 0.}, *timePtr;

     char buf[2];

     if (pipe(fds) != 0) {

 	panic("NotifierThreadProc: could not create trigger pipe.");

     }

     receivePipe = fds[0];

 #ifndef USE_FIONBIO

     status = fcntl(receivePipe, F_GETFL);

     status |= O_NONBLOCK;

     if (fcntl(receivePipe, F_SETFL, status) < 0) {

 	panic("NotifierThreadProc: could not make receive pipe non blocking.");

     }

     status = fcntl(fds[1], F_GETFL);

     status |= O_NONBLOCK;

     if (fcntl(fds[1], F_SETFL, status) < 0) {

 	panic("NotifierThreadProc: could not make trigger pipe non blocking.");

     }

 #else

     if (ioctl(receivePipe, (int) FIONBIO, &status) < 0) {

 	panic("NotifierThreadProc: could not make receive pipe non blocking.");

     }

     if (ioctl(fds[1], (int) FIONBIO, &status) < 0) {

 	panic("NotifierThreadProc: could not make trigger pipe non blocking.");

     }

 #endif

     /*

      * Install the write end of the pipe into the global variable.

      */

     Tcl_MutexLock(&notifierMutex);

     triggerPipe = fds[1];

     /*

      * Signal any threads that are waiting.

      */

     Tcl_ConditionNotify(&notifierCV);

     Tcl_MutexUnlock(&notifierMutex);

     /*

      * Look for file events and report them to interested threads.

      */

     while (1) {

 	FD_ZERO( &readableMask );

 	FD_ZERO( &writableMask );

 	FD_ZERO( &exceptionalMask );

 	/*

 	 * Compute the logical OR of the select masks from all the

 	 * waiting notifiers.

 	 */

 	Tcl_MutexLock(&notifierMutex);

 	timePtr = NULL;

         for (tsdPtr = waitingListPtr; tsdPtr; tsdPtr = tsdPtr->nextPtr) {

 	    for ( i = tsdPtr->numFdBits-1; i >= 0; --i ) {

 		if ( FD_ISSET( i, &(tsdPtr->checkMasks.readable) ) ) {

 		    FD_SET( i, &readableMask );

 		}

 		if ( FD_ISSET( i, &(tsdPtr->checkMasks.writable) ) ) {

 		    FD_SET( i, &writableMask );

 		}

 		if ( FD_ISSET( i, &(tsdPtr->checkMasks.exceptional) ) ) {

 		    FD_SET( i, &exceptionalMask );

 		}

 	    }

 	    if ( tsdPtr->numFdBits > numFdBits ) {

 		numFdBits = tsdPtr->numFdBits;

 	    }

 	    if (tsdPtr->pollState & POLL_WANT) {

 		/*

 		 * Here we make sure we go through select() with the same

 		 * mask bits that were present when the thread tried to poll.

 		 */

 		tsdPtr->pollState |= POLL_DONE;

 		timePtr = &poll;

 	    }

 	}

 	Tcl_MutexUnlock(&notifierMutex);

 	/*

 	 * Set up the select mask to include the receive pipe.

 	 */

 	if ( receivePipe >= numFdBits ) {

 	    numFdBits = receivePipe + 1;

 	}

 	FD_SET( receivePipe, &readableMask );

 	if ( select( numFdBits, &readableMask, &writableMask,

 		     &exceptionalMask, timePtr) == -1 ) {

 	    /*

 	     * Try again immediately on an error.

 	     */

 	    continue;

         }

 	/*

 	 * Alert any threads that are waiting on a ready file descriptor.

 	 */

 	Tcl_MutexLock(&notifierMutex);

         for (tsdPtr = waitingListPtr; tsdPtr; tsdPtr = tsdPtr->nextPtr) {

 	    found = 0;

 	    for ( i = tsdPtr->numFdBits-1; i >= 0; --i ) {

 		if ( FD_ISSET( i, &(tsdPtr->checkMasks.readable) )

 		     && FD_ISSET( i, &readableMask ) ) {

 		    FD_SET( i, &(tsdPtr->readyMasks.readable) );

 		    found = 1;

 		}

 		if ( FD_ISSET( i, &(tsdPtr->checkMasks.writable) )

 		     && FD_ISSET( i, &writableMask ) ) {

 		    FD_SET( i, &(tsdPtr->readyMasks.writable) );

 		    found = 1;

 		}

 		if ( FD_ISSET( i, &(tsdPtr->checkMasks.exceptional) )

 		     && FD_ISSET( i, &exceptionalMask ) ) {

 		    FD_SET( i, &(tsdPtr->readyMasks.exceptional) );

 		    found = 1;

 		}

 	    }

             if (found || (tsdPtr->pollState & POLL_DONE)) {

                 tsdPtr->eventReady = 1;

 		if (tsdPtr->onList) {

 		    /*

 		     * Remove the ThreadSpecificData structure of this

 		     * thread from the waiting list. This prevents us from

 		     * continuously spining on select until the other

 		     * threads runs and services the file event.

 		     */

 		    if (tsdPtr->prevPtr) {

 			tsdPtr->prevPtr->nextPtr = tsdPtr->nextPtr;

 		    } else {

 			waitingListPtr = tsdPtr->nextPtr;

 		    }

 		    if (tsdPtr->nextPtr) {

 			tsdPtr->nextPtr->prevPtr = tsdPtr->prevPtr;

 		    }

 		    tsdPtr->nextPtr = tsdPtr->prevPtr = NULL;

 		    tsdPtr->onList = 0;

 		    tsdPtr->pollState = 0;

 		}

 		Tcl_ConditionNotify(&tsdPtr->waitCV);

             }

         }

 	Tcl_MutexUnlock(&notifierMutex);

 	/*

 	 * Consume the next byte from the notifier pipe if the pipe was

 	 * readable.  Note that there may be multiple bytes pending, but

 	 * to avoid a race condition we only read one at a time.

 	 */

 	if ( FD_ISSET( receivePipe, &readableMask ) ) {

 	    i = read(receivePipe, buf, 1);

 	    if ((i == 0) || ((i == 1) && (buf[0] == 'q'))) {

 		/*

 		 * Someone closed the write end of the pipe or sent us a

 		 * Quit message [Bug: 4139] and then closed the write end

 		 * of the pipe so we need to shut down the notifier thread.

 		 */

 		break;

 	    }

 	}

     }

     /*

      * Clean up the read end of the pipe and signal any threads waiting on

      * termination of the notifier thread.

      */

     close(receivePipe);

     Tcl_MutexLock(&notifierMutex);

     triggerPipe = -1;

     Tcl_ConditionNotify(&notifierCV);

     Tcl_MutexUnlock(&notifierMutex);

     TclpThreadExit (0);

 }

 #endif

 #endif /* HAVE_COREFOUNDATION */