/* 
 * tclEvent.c --
 *
 *	This file implements some general event related interfaces including
 *	background errors, exit handlers, and the "vwait" and "update" command
 *	procedures.
 *
 * Copyright (c) 1990-1994 The Regents of the University of California.
 * Copyright (c) 1994-1998 Sun Microsystems, Inc.
 * Copyright (c) 2004 by Zoran Vasiljevic.
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclEvent.c,v 1.62 2005/08/10 16:28:02 kennykb Exp $
 */

#include "tclInt.h"

/*
 * The data structure below is used to report background errors.  One such
 * structure is allocated for each error; it holds information about the
 * interpreter and the error until an idle handler command can be invoked.
 */

typedef struct BgError {
    Tcl_Obj *errorMsg;		/* Copy of the error message (the interp's
				 * result when the error occurred). */
    Tcl_Obj *returnOpts;	/* Active return options when the error
				 * occurred */
    struct BgError *nextPtr;	/* Next in list of all pending error reports
				 * for this interpreter, or NULL for end of
				 * list. */
} BgError;

/*
 * One of the structures below is associated with the "tclBgError" assoc data
 * for each interpreter.  It keeps track of the head and tail of the list of
 * pending background errors for the interpreter.
 */

typedef struct ErrAssocData {
    Tcl_Interp *interp;		/* Interpreter in which error occurred. */
    Tcl_Obj *cmdPrefix;		/* First word(s) of the handler command */
    BgError *firstBgPtr;	/* First in list of all background errors
				 * waiting to be processed for this
				 * interpreter (NULL if none). */
    BgError *lastBgPtr;		/* Last in list of all background errors
				 * waiting to be processed for this
				 * interpreter (NULL if none). */
} ErrAssocData;

/*
 * For each exit handler created with a call to Tcl_CreateExitHandler
 * there is a structure of the following type:
 */

typedef struct ExitHandler {
    Tcl_ExitProc *proc;		/* Procedure to call when process exits. */
    ClientData clientData;	/* One word of information to pass to proc. */
    struct ExitHandler *nextPtr;/* Next in list of all exit handlers for this
				 * application, or NULL for end of list. */
} ExitHandler;

/*
 * There is both per-process and per-thread exit handlers.  The first list is
 * controlled by a mutex.  The other is in thread local storage.
 */

static ExitHandler *firstExitPtr = NULL;
				/* First in list of all exit handlers for
				 * application. */
TCL_DECLARE_MUTEX(exitMutex)

/*
 * This variable is set to 1 when Tcl_Finalize is called, and at the end of
 * its work, it is reset to 0. The variable is checked by TclInExit() to allow
 * different behavior for exit-time processing, e.g. in closing of files and
 * pipes.
 */

static int inFinalize = 0;
static int subsystemsInitialized = 0;

/*
 * This variable contains the application wide exit handler.  It will be
 * called by Tcl_Exit instead of the C-runtime exit if this variable is set
 * to a non-NULL value.
 */

static Tcl_ExitProc *appExitPtr = NULL;

typedef struct ThreadSpecificData {
    ExitHandler *firstExitPtr;  /* First in list of all exit handlers for this
				 * thread. */
    int inExit;			/* True when this thread is exiting. This is
				 * used as a hack to decide to close the
				 * standard channels. */
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;

#ifdef TCL_THREADS

typedef struct {
    Tcl_ThreadCreateProc *proc;	/* Main() function of the thread */
    ClientData clientData;	/* The one argument to Main() */
} ThreadClientData;
static Tcl_ThreadCreateType NewThreadProc _ANSI_ARGS_((
	ClientData clientData));
#endif

/*
 * Prototypes for procedures referenced only in this file:
 */

static void		BgErrorDeleteProc _ANSI_ARGS_((ClientData clientData,
			    Tcl_Interp *interp));
static void		HandleBgErrors _ANSI_ARGS_((ClientData clientData));
static char *		VwaitVarProc _ANSI_ARGS_((ClientData clientData,
			    Tcl_Interp *interp, CONST char *name1, 
			    CONST char *name2, int flags));

/*
 *----------------------------------------------------------------------
 *
 * Tcl_BackgroundError --
 *
 *	This procedure is invoked to handle errors that occur in Tcl commands
 *	that are invoked in "background" (e.g. from event or timer bindings).
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	A handler command is invoked later as an idle handler to process the
 *	error, passing it the interp result and return options.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_BackgroundError(interp)
    Tcl_Interp *interp;		/* Interpreter in which an error has
				 * occurred. */
{
    BgError *errPtr;
    ErrAssocData *assocPtr;

    errPtr = (BgError *) ckalloc(sizeof(BgError));
    errPtr->errorMsg = Tcl_GetObjResult(interp);
    Tcl_IncrRefCount(errPtr->errorMsg);
    errPtr->returnOpts = Tcl_GetReturnOptions(interp, TCL_ERROR);
    Tcl_IncrRefCount(errPtr->returnOpts);
    errPtr->nextPtr = NULL;

    (void) TclGetBgErrorHandler(interp);
    assocPtr = (ErrAssocData *) Tcl_GetAssocData(interp, "tclBgError",
	    (Tcl_InterpDeleteProc **) NULL);
    if (assocPtr->firstBgPtr == NULL) {
	assocPtr->firstBgPtr = errPtr;
	Tcl_DoWhenIdle(HandleBgErrors, (ClientData) assocPtr);
    } else {
	assocPtr->lastBgPtr->nextPtr = errPtr;
    }
    assocPtr->lastBgPtr = errPtr;
    Tcl_ResetResult(interp);
}

/*
 *----------------------------------------------------------------------
 *
 * HandleBgErrors --
 *
 *	This procedure is invoked as an idle handler to process all of the
 *	accumulated background errors.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Depends on what actions the handler command takes for the errors.
 *
 *----------------------------------------------------------------------
 */

static void
HandleBgErrors(clientData)
    ClientData clientData;	/* Pointer to ErrAssocData structure. */
{
    ErrAssocData *assocPtr = (ErrAssocData *) clientData;
    Tcl_Interp *interp = assocPtr->interp;
    BgError *errPtr;

    /*
     * Not bothering to save/restore the interp state.  Assume that any code
     * that has interp state it needs to keep will make its own
     * Tcl_SaveInterpState call before calling something like Tcl_DoOneEvent()
     * that could lead us here.
     */

    Tcl_Preserve((ClientData) assocPtr);
    Tcl_Preserve((ClientData) interp);
    while (assocPtr->firstBgPtr != NULL) {
	int code, prefixObjc;
	Tcl_Obj **prefixObjv, **tempObjv;

	errPtr = assocPtr->firstBgPtr;

	Tcl_IncrRefCount(assocPtr->cmdPrefix);
	Tcl_ListObjGetElements(NULL, assocPtr->cmdPrefix, &prefixObjc,
		&prefixObjv);
	tempObjv = (Tcl_Obj **) ckalloc((prefixObjc+2)*sizeof(Tcl_Obj *));
	memcpy(tempObjv, prefixObjv, prefixObjc*sizeof(Tcl_Obj *));
	tempObjv[prefixObjc] = errPtr->errorMsg;
	tempObjv[prefixObjc+1] = errPtr->returnOpts;
	Tcl_AllowExceptions(interp);
	code = Tcl_EvalObjv(interp, prefixObjc+2, tempObjv, TCL_EVAL_GLOBAL);

	/*
	 * Discard the command and the information about the error report.
	 */

	Tcl_DecrRefCount(assocPtr->cmdPrefix);
	Tcl_DecrRefCount(errPtr->errorMsg);
	Tcl_DecrRefCount(errPtr->returnOpts);
	assocPtr->firstBgPtr = errPtr->nextPtr;
	ckfree((char *) errPtr);

	if (code == TCL_BREAK) {
	    /*
	     * Break means cancel any remaining error reports for this
	     * interpreter.
	     */
	    while (assocPtr->firstBgPtr != NULL) {
		errPtr = assocPtr->firstBgPtr;
		assocPtr->firstBgPtr = errPtr->nextPtr;
		Tcl_DecrRefCount(errPtr->errorMsg);
		Tcl_DecrRefCount(errPtr->returnOpts);
		ckfree((char *) errPtr);
	    }
	} else if ((code == TCL_ERROR) && !Tcl_IsSafe(interp)) {
	    Tcl_Channel errChannel = Tcl_GetStdChannel(TCL_STDERR);
	    if (errChannel != (Tcl_Channel) NULL) {
		Tcl_Obj *options = Tcl_GetReturnOptions(interp, code);
		Tcl_Obj *keyPtr = Tcl_NewStringObj("-errorinfo", -1);
		Tcl_Obj *valuePtr;

		Tcl_IncrRefCount(keyPtr);
		Tcl_DictObjGet(NULL, options, keyPtr, &valuePtr);
		Tcl_DecrRefCount(keyPtr);

		Tcl_WriteChars(errChannel,
			"error in background error handler:\n", -1);
		if (valuePtr) {
		    Tcl_WriteObj(errChannel, valuePtr);
		} else {
		    Tcl_WriteObj(errChannel, Tcl_GetObjResult(interp));
		}
		Tcl_WriteChars(errChannel, "\n", 1);
		Tcl_Flush(errChannel);
	    }
	}
    }
    assocPtr->lastBgPtr = NULL;
    Tcl_Release((ClientData) interp);
    Tcl_Release((ClientData) assocPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * TclDefaultBgErrorHandlerObjCmd --
 *
 *	This procedure is invoked to process the "::tcl::Bgerror" Tcl command.
 *	It is the default handler command registered with [interp bgerror] for
 *	the sake of compatibility with older Tcl releases.
 *
 * Results:
 *	A standard Tcl object result.
 *
 * Side effects:
 *	Depends on what actions the "bgerror" command takes for the errors.
 *
 *----------------------------------------------------------------------
 */

int
TclDefaultBgErrorHandlerObjCmd(dummy, interp, objc, objv)
    ClientData dummy;		/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    Tcl_Obj *keyPtr, *valuePtr;
    Tcl_Obj *tempObjv[2];
    int code;

    if (objc != 3) {
	Tcl_WrongNumArgs(interp, 1, objv, "msg options");
	return TCL_ERROR;
    }

    /*
     * Restore important state variables to what they were at the time the
     * error occurred.
     *
     * Need to set the variables, not the interp fields, because Tcl_EvalObjv
     * calls Tcl_ResetResult which would destroy anything we write to the
     * interp fields.
     */

    keyPtr = Tcl_NewStringObj("-errorcode", -1);
    Tcl_IncrRefCount(keyPtr);
    Tcl_DictObjGet(NULL, objv[2], keyPtr, &valuePtr);
    Tcl_DecrRefCount(keyPtr);
    if (valuePtr) {
	Tcl_SetVar2Ex(interp, "errorCode", NULL, valuePtr, TCL_GLOBAL_ONLY);
    }

    keyPtr = Tcl_NewStringObj("-errorinfo", -1);
    Tcl_IncrRefCount(keyPtr);
    Tcl_DictObjGet(NULL, objv[2], keyPtr, &valuePtr);
    Tcl_DecrRefCount(keyPtr);
    if (valuePtr) {
	Tcl_SetVar2Ex(interp, "errorInfo", NULL, valuePtr, TCL_GLOBAL_ONLY);
    }

    /*
     * Create and invoke the bgerror command.
     */

    tempObjv[0] = Tcl_NewStringObj("bgerror", -1);
    Tcl_IncrRefCount(tempObjv[0]);
    tempObjv[1] = objv[1];
    Tcl_AllowExceptions(interp);
    code = Tcl_EvalObjv(interp, 2, tempObjv, TCL_EVAL_GLOBAL);
    if (code == TCL_ERROR) {
	/*
	 * If the interpreter is safe, we look for a hidden command named
	 * "bgerror" and call that with the error information. Otherwise,
	 * simply ignore the error. The rationale is that this could be an
	 * error caused by a malicious applet trying to cause an infinite
	 * barrage of error messages. The hidden "bgerror" command can be used
	 * by a security policy to interpose on such attacks and e.g. kill the
	 * applet after a few attempts.
	 */

	if (Tcl_IsSafe(interp)) {
	    Tcl_ResetResult(interp);
	    TclObjInvoke(interp, 2, tempObjv, TCL_INVOKE_HIDDEN);
	} else {
	    Tcl_Channel errChannel = Tcl_GetStdChannel(TCL_STDERR);
	    if (errChannel != (Tcl_Channel) NULL) {
		Tcl_Obj *resultPtr = Tcl_GetObjResult(interp);

		Tcl_IncrRefCount(resultPtr);
		if (Tcl_FindCommand(interp, "bgerror", NULL,
			TCL_GLOBAL_ONLY) == NULL) {
		    if (valuePtr) {
			Tcl_WriteObj(errChannel, valuePtr);
			Tcl_WriteChars(errChannel, "\n", -1);
		    }
		} else {
		    Tcl_WriteChars(errChannel,
			    "bgerror failed to handle background error.\n", -1);
		    Tcl_WriteChars(errChannel, "    Original error: ", -1);
		    Tcl_WriteObj(errChannel, objv[1]);
		    Tcl_WriteChars(errChannel, "\n", -1);
		    Tcl_WriteChars(errChannel, "    Error in bgerror: ", -1);
		    Tcl_WriteObj(errChannel, resultPtr);
		    Tcl_WriteChars(errChannel, "\n", -1);
		}
		Tcl_DecrRefCount(resultPtr);
		Tcl_Flush(errChannel);
	    }
	}
	code = TCL_OK;
    }
    Tcl_DecrRefCount(tempObjv[0]);
    Tcl_ResetResult(interp);
    return code;
}

/*
 *----------------------------------------------------------------------
 *
 * TclSetBgErrorHandler --
 *
 *	This procedure sets the command prefix to be used to handle background
 *	errors in interp.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Error handler is registered.
 *
 *----------------------------------------------------------------------
 */

void
TclSetBgErrorHandler(interp, cmdPrefix)
    Tcl_Interp *interp;
    Tcl_Obj *cmdPrefix;
{
    ErrAssocData *assocPtr = (ErrAssocData *) Tcl_GetAssocData(interp,
	    "tclBgError", (Tcl_InterpDeleteProc **) NULL);

    if (cmdPrefix == NULL) {
	Tcl_Panic("TclSetBgErrorHandler: NULL cmdPrefix argument");
    }
    if (assocPtr == NULL) {
	/* First access: initialize */
	assocPtr = (ErrAssocData *) ckalloc(sizeof(ErrAssocData));
	assocPtr->interp = interp;
	assocPtr->cmdPrefix = NULL;
	assocPtr->firstBgPtr = NULL;
	assocPtr->lastBgPtr = NULL;
	Tcl_SetAssocData(interp, "tclBgError", BgErrorDeleteProc,
		(ClientData) assocPtr);
    }
    if (assocPtr->cmdPrefix) {
	Tcl_DecrRefCount(assocPtr->cmdPrefix);
    }
    assocPtr->cmdPrefix = cmdPrefix;
    Tcl_IncrRefCount(assocPtr->cmdPrefix);
}

/*
 *----------------------------------------------------------------------
 *
 * TclGetBgErrorHandler --
 *
 *	This procedure retrieves the command prefix currently used to handle
 *	background errors in interp.
 *
 * Results:
 *	A (Tcl_Obj *) to a list of words (command prefix).
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
TclGetBgErrorHandler(interp)
    Tcl_Interp *interp;
{
    ErrAssocData *assocPtr = (ErrAssocData *) Tcl_GetAssocData(interp,
	    "tclBgError", (Tcl_InterpDeleteProc **) NULL);

    if (assocPtr == NULL) {
	TclSetBgErrorHandler(interp, Tcl_NewStringObj("::tcl::Bgerror", -1));
	assocPtr = (ErrAssocData *) Tcl_GetAssocData(interp,
	    "tclBgError", (Tcl_InterpDeleteProc **) NULL);
    }
    return assocPtr->cmdPrefix;
}

/*
 *----------------------------------------------------------------------
 *
 * BgErrorDeleteProc --
 *
 *	This procedure is associated with the "tclBgError" assoc data for an
 *	interpreter; it is invoked when the interpreter is deleted in order to
 *	free the information assoicated with any pending error reports.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Background error information is freed: if there were any pending error
 *	reports, they are cancelled.
 *
 *----------------------------------------------------------------------
 */

static void
BgErrorDeleteProc(clientData, interp)
    ClientData clientData;	/* Pointer to ErrAssocData structure. */
    Tcl_Interp *interp;		/* Interpreter being deleted. */
{
    ErrAssocData *assocPtr = (ErrAssocData *) clientData;
    BgError *errPtr;

    while (assocPtr->firstBgPtr != NULL) {
	errPtr = assocPtr->firstBgPtr;
	assocPtr->firstBgPtr = errPtr->nextPtr;
	Tcl_DecrRefCount(errPtr->errorMsg);
	Tcl_DecrRefCount(errPtr->returnOpts);
	ckfree((char *) errPtr);
    }
    Tcl_CancelIdleCall(HandleBgErrors, (ClientData) assocPtr);
    Tcl_DecrRefCount(assocPtr->cmdPrefix);
    Tcl_EventuallyFree((ClientData) assocPtr, TCL_DYNAMIC);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_CreateExitHandler --
 *
 *	Arrange for a given procedure to be invoked just before the
 *	application exits.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Proc will be invoked with clientData as argument when the application
 *	exits.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_CreateExitHandler(proc, clientData)
    Tcl_ExitProc *proc;		/* Procedure to invoke. */
    ClientData clientData;	/* Arbitrary value to pass to proc. */
{
    ExitHandler *exitPtr;

    exitPtr = (ExitHandler *) ckalloc(sizeof(ExitHandler));
    exitPtr->proc = proc;
    exitPtr->clientData = clientData;
    Tcl_MutexLock(&exitMutex);
    exitPtr->nextPtr = firstExitPtr;
    firstExitPtr = exitPtr;
    Tcl_MutexUnlock(&exitMutex);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DeleteExitHandler --
 *
 *	This procedure cancels an existing exit handler matching proc and
 *	clientData, if such a handler exits.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	If there is an exit handler corresponding to proc and clientData then
 *	it is cancelled; if no such handler exists then nothing happens.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DeleteExitHandler(proc, clientData)
    Tcl_ExitProc *proc;		/* Procedure that was previously registered. */
    ClientData clientData;	/* Arbitrary value to pass to proc. */
{
    ExitHandler *exitPtr, *prevPtr;

    Tcl_MutexLock(&exitMutex);
    for (prevPtr = NULL, exitPtr = firstExitPtr; exitPtr != NULL;
	    prevPtr = exitPtr, exitPtr = exitPtr->nextPtr) {
	if ((exitPtr->proc == proc)
		&& (exitPtr->clientData == clientData)) {
	    if (prevPtr == NULL) {
		firstExitPtr = exitPtr->nextPtr;
	    } else {
		prevPtr->nextPtr = exitPtr->nextPtr;
	    }
	    ckfree((char *) exitPtr);
	    break;
	}
    }
    Tcl_MutexUnlock(&exitMutex);
    return;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_CreateThreadExitHandler --
 *
 *	Arrange for a given procedure to be invoked just before the current
 *	thread exits.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Proc will be invoked with clientData as argument when the application
 *	exits.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_CreateThreadExitHandler(proc, clientData)
    Tcl_ExitProc *proc;		/* Procedure to invoke. */
    ClientData clientData;	/* Arbitrary value to pass to proc. */
{
    ExitHandler *exitPtr;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    exitPtr = (ExitHandler *) ckalloc(sizeof(ExitHandler));
    exitPtr->proc = proc;
    exitPtr->clientData = clientData;
    exitPtr->nextPtr = tsdPtr->firstExitPtr;
    tsdPtr->firstExitPtr = exitPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DeleteThreadExitHandler --
 *
 *	This procedure cancels an existing exit handler matching proc and
 *	clientData, if such a handler exits.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	If there is an exit handler corresponding to proc and clientData then
 *	it is cancelled; if no such handler exists then nothing happens.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DeleteThreadExitHandler(proc, clientData)
    Tcl_ExitProc *proc;		/* Procedure that was previously registered. */
    ClientData clientData;	/* Arbitrary value to pass to proc. */
{
    ExitHandler *exitPtr, *prevPtr;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    for (prevPtr = NULL, exitPtr = tsdPtr->firstExitPtr; exitPtr != NULL;
	    prevPtr = exitPtr, exitPtr = exitPtr->nextPtr) {
	if ((exitPtr->proc == proc)
		&& (exitPtr->clientData == clientData)) {
	    if (prevPtr == NULL) {
		tsdPtr->firstExitPtr = exitPtr->nextPtr;
	    } else {
		prevPtr->nextPtr = exitPtr->nextPtr;
	    }
	    ckfree((char *) exitPtr);
	    return;
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetExitProc --
 *
 *	This procedure sets the application wide exit handler that will be
 *	called by Tcl_Exit in place of the C-runtime exit.  If the application
 *	wide exit handler is NULL, the C-runtime exit will be used instead.
 *
 * Results:
 *	The previously set application wide exit handler.
 *
 * Side effects:
 *	Sets the application wide exit handler to the specified value.
 *
 *----------------------------------------------------------------------
 */

Tcl_ExitProc *
Tcl_SetExitProc(proc)
    Tcl_ExitProc *proc; /* new exit handler for app or NULL */
{
    Tcl_ExitProc *prevExitProc;

    /*
     * Swap the old exit proc for the new one, saving the old one for our
     * return value.
     */

    Tcl_MutexLock(&exitMutex);
    prevExitProc = appExitPtr;
    appExitPtr = proc;
    Tcl_MutexUnlock(&exitMutex);

    return prevExitProc;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Exit --
 *
 *	This procedure is called to terminate the application.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	All existing exit handlers are invoked, then the application ends.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_Exit(status)
    int status;			/* Exit status for application;  typically
				 * 0 for normal return, 1 for error return. */
{
    Tcl_ExitProc *currentAppExitPtr;

    Tcl_MutexLock(&exitMutex);
    currentAppExitPtr = appExitPtr;
    Tcl_MutexUnlock(&exitMutex);

    if (currentAppExitPtr) {
	/*
	 * Warning: this code SHOULD NOT return, as there is code that depends
	 * on Tcl_Exit never returning.  In fact, we will Tcl_Panic if anyone
	 * returns, so critical is this dependcy.
	 */

	currentAppExitPtr((ClientData) status);
	Tcl_Panic("AppExitProc returned unexpectedly");
    } else {
	/* use default handling */
	Tcl_Finalize();
	TclpExit(status);
	Tcl_Panic("OS exit failed!");
    }
}

/*
 *-------------------------------------------------------------------------
 *
 * TclInitSubsystems --
 *
 *	Initialize various subsytems in Tcl.  This should be called the first
 *	time an interp is created, or before any of the subsystems are used.
 *	This function ensures an order for the initialization of subsystems:
 *
 *	1. that cannot be initialized in lazy order because they are mutually
 *	dependent.
 *
 *	2. so that they can be finalized in a known order w/o causing the
 *	subsequent re-initialization of a subsystem in the act of shutting
 *	down another.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Varied, see the respective initialization routines.
 *
 *-------------------------------------------------------------------------
 */

void
TclInitSubsystems()
{
    if (inFinalize != 0) {
	Tcl_Panic("TclInitSubsystems called while finalizing");
    }

    if (subsystemsInitialized == 0) {
	/* 
	 * Double check inside the mutex.  There are definitly calls back into
	 * this routine from some of the procedures below.
	 */

	TclpInitLock();
	if (subsystemsInitialized == 0) {
	    /*
	     * Have to set this bit here to avoid deadlock with the routines
	     * below us that call into TclInitSubsystems.
	     */

	    subsystemsInitialized = 1;

	    /*
	     * Initialize locks used by the memory allocators before anything
	     * interesting happens so we can use the allocators in the
	     * implementation of self-initializing locks.
	     */

#if USE_TCLALLOC
	    TclInitAlloc();		/* Process wide mutex init */
#endif
#ifdef TCL_MEM_DEBUG
	    TclInitDbCkalloc();		/* Process wide mutex init */
#endif

	    TclpInitPlatform();		/* Creates signal handler(s) */
	    TclInitDoubleConversion();	/* Initializes constants for
					 * converting to/from double. */
    	    TclInitObjSubsystem();	/* Register obj types, create
					 * mutexes. */
	    TclInitIOSubsystem();	/* Inits a tsd key (noop). */
	    TclInitEncodingSubsystem();	/* Process wide encoding init. */
	    TclpSetInterfaces();
    	    TclInitNamespaceSubsystem();/* Register ns obj type (mutexed). */
	}
	TclpInitUnlock();
    }
    TclInitNotifier();
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Finalize --
 *
 *	Shut down Tcl.  First calls registered exit handlers, then carefully
 *	shuts down various subsystems.  Called by Tcl_Exit or when the Tcl
 *	shared library is being unloaded.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Varied, see the respective finalization routines.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_Finalize()
{
    ExitHandler *exitPtr;
    
    /*
     * Invoke exit handlers first.
     */

    Tcl_MutexLock(&exitMutex);
    inFinalize = 1;
    for (exitPtr = firstExitPtr; exitPtr != NULL; exitPtr = firstExitPtr) {
	/*
	 * Be careful to remove the handler from the list before invoking its
	 * callback.  This protects us against double-freeing if the callback
	 * should call Tcl_DeleteExitHandler on itself.
	 */

	firstExitPtr = exitPtr->nextPtr;
	Tcl_MutexUnlock(&exitMutex);
	(*exitPtr->proc)(exitPtr->clientData);
	ckfree((char *) exitPtr);
	Tcl_MutexLock(&exitMutex);
    }    
    firstExitPtr = NULL;
    Tcl_MutexUnlock(&exitMutex);

    TclpInitLock();
    if (subsystemsInitialized != 0) {
	subsystemsInitialized = 0;

	/*
	 * Ensure the thread-specific data is initialised as it is used in
	 * Tcl_FinalizeThread()
	 */

	(void) TCL_TSD_INIT(&dataKey);

	/*
	 * Clean up after the current thread now, after exit handlers.  In
	 * particular, the testexithandler command sets up something that
	 * writes to standard output, which gets closed.  Note that there is
	 * no thread-local storage after this call.
	 */

	Tcl_FinalizeThread();

	/*
	 * Now finalize the Tcl execution environment.  Note that this must be
	 * done after the exit handlers, because there are order dependencies.
	 */

	TclFinalizeCompilation();
	TclFinalizeExecution();
	TclFinalizeEnvironment();

	/* 
	 * Finalizing the filesystem must come after anything which might
	 * conceivably interact with the 'Tcl_FS' API.
	 */

	TclFinalizeFilesystem();

	/*
	 * Undo all Tcl_ObjType registrations, and reset the master list
	 * of free Tcl_Obj's.  After this returns, no more Tcl_Obj's should
	 * be allocated or freed.  
	 *
	 * Note in particular that TclFinalizeObjects() must follow
	 * TclFinalizeFilesystem() because TclFinalizeFilesystem free's
	 * the Tcl_Obj that holds the path of the current working directory.
	 */

	TclFinalizeObjects();

	/* 
	 * We must be sure the encoding finalization doesn't need to examine
	 * the filesystem in any way.  Since it only needs to clean up
	 * internal data structures, this is fine.
	 */

	TclFinalizeEncodingSubsystem();

	Tcl_SetPanicProc(NULL);

	/*
	 * Repeat finalization of the thread local storage once more. Although
	 * this step is already done by the Tcl_FinalizeThread call above,
	 * series of events happening afterwards may re-initialize TSD slots.
	 * Those need to be finalized again, otherwise we're leaking memory
	 * chunks. Very important to note is that things happening afterwards
	 * should not reference anything which may re-initialize TSD's. This
	 * includes freeing Tcl_Objs's, among other things.
	 *
	 * This fixes the Tcl Bug #990552.
	 */

	TclFinalizeThreadData();

	/*
	 * Now we can free constants for conversions to/from double.
	 */

	TclFinalizeDoubleConversion();
	
	/*
	 * There have been several bugs in the past that cause exit handlers
	 * to be established during Tcl_Finalize processing. Such exit
	 * handlers leave malloc'ed memory, and Tcl_FinalizeThreadAlloc or
	 * Tcl_FinalizeMemorySubsystem will result in a corrupted heap. The
	 * result can be a mysterious crash on process exit. Check here that
	 * nobody's done this.
	 */

	if (firstExitPtr != NULL) {
	    Tcl_Panic("exit handlers were created during Tcl_Finalize");
	}

	TclFinalizePreserve();

	/*
	 * Free synchronization objects.  There really should only be one
	 * thread alive at this moment.
	 */

	TclFinalizeSynchronization();

#if defined(TCL_THREADS) && defined(USE_THREAD_ALLOC)
	TclFinalizeThreadAlloc();
#endif

	/*
	 * We defer unloading of packages until very late to avoid memory
	 * access issues.  Both exit callbacks and synchronization variables
	 * may be stored in packages.
	 * 
	 * Note that TclFinalizeLoad unloads packages in the reverse of the
	 * order they were loaded in (i.e. last to be loaded is the first to
	 * be unloaded).  This can be important for correct unloading when
	 * dependencies exist.
	 * 
	 * Once load has been finalized, we will have deleted any temporary
	 * copies of shared libraries and can therefore reset the filesystem
	 * to its original state.
	 */

	TclFinalizeLoad();
	TclResetFilesystem();

	/*
	 * At this point, there should no longer be any ckalloc'ed memory.
	 */

	TclFinalizeMemorySubsystem();
	inFinalize = 0;
    }
    TclFinalizeLock();
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_FinalizeThread --
 *
 *	Runs the exit handlers to allow Tcl to clean up its state about a
 *	particular thread.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Varied, see the respective finalization routines.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_FinalizeThread()
{
    ExitHandler *exitPtr;
    ThreadSpecificData *tsdPtr =
	    (ThreadSpecificData *)TclThreadDataKeyGet(&dataKey);

    if (tsdPtr != NULL) {
	tsdPtr->inExit = 1;

	for (exitPtr = tsdPtr->firstExitPtr; exitPtr != NULL;
		exitPtr = tsdPtr->firstExitPtr) {
	    /*
	     * Be careful to remove the handler from the list before invoking
	     * its callback.  This protects us against double-freeing if the
	     * callback should call Tcl_DeleteThreadExitHandler on itself.
	     */

	    tsdPtr->firstExitPtr = exitPtr->nextPtr;
	    (*exitPtr->proc)(exitPtr->clientData);
	    ckfree((char *) exitPtr);
	}
	TclFinalizeIOSubsystem();
	TclFinalizeNotifier();
	TclFinalizeAsync();
    }

    /*
     * Blow away all thread local storage blocks.
     *
     * Note that Tcl API allows creation of threads which do not use any Tcl
     * interp or other Tcl subsytems. Those threads might, however, use thread
     * local storage, so we must unconditionally finalize it.
     *
     * Fix [Bug #571002]
     */

    TclFinalizeThreadData();
}

/*
 *----------------------------------------------------------------------
 *
 * TclInExit --
 *
 *	Determines if we are in the middle of exit-time cleanup.
 *
 * Results:
 *	If we are in the middle of exiting, 1, otherwise 0.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
TclInExit()
{
    return inFinalize;
}

/*
 *----------------------------------------------------------------------
 *
 * TclInThreadExit --
 *
 *	Determines if we are in the middle of thread exit-time cleanup.
 *
 * Results:
 *	If we are in the middle of exiting this thread, 1, otherwise 0.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
TclInThreadExit()
{
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *)
	    TclThreadDataKeyGet(&dataKey);
    if (tsdPtr == NULL) {
	return 0;
    } else {
	return tsdPtr->inExit;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_VwaitObjCmd --
 *
 *	This procedure is invoked to process the "vwait" Tcl command. See the
 *	user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_VwaitObjCmd(clientData, interp, objc, objv)
    ClientData clientData;	/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    int done, foundEvent;
    char *nameString;

    if (objc != 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "name");
	return TCL_ERROR;
    }
    nameString = Tcl_GetString(objv[1]);
    if (Tcl_TraceVar(interp, nameString,
	    TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
	    VwaitVarProc, (ClientData) &done) != TCL_OK) {
	return TCL_ERROR;
    };
    done = 0;
    foundEvent = 1;
    while (!done && foundEvent) {
	foundEvent = Tcl_DoOneEvent(TCL_ALL_EVENTS);
	if (Tcl_LimitExceeded(interp)) {
	    Tcl_ResetResult(interp);
	    Tcl_AppendResult(interp, "limit exceeded", NULL);
	    return TCL_ERROR;
	}
    }
    Tcl_UntraceVar(interp, nameString,
	    TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
	    VwaitVarProc, (ClientData) &done);

    /*
     * Clear out the interpreter's result, since it may have been set by event
     * handlers.
     */

    Tcl_ResetResult(interp);
    if (!foundEvent) {
	Tcl_AppendResult(interp, "can't wait for variable \"", nameString,
		"\":  would wait forever", (char *) NULL);
	return TCL_ERROR;
    }
    return TCL_OK;
}

	/* ARGSUSED */
static char *
VwaitVarProc(clientData, interp, name1, name2, flags)
    ClientData clientData;	/* Pointer to integer to set to 1. */
    Tcl_Interp *interp;		/* Interpreter containing variable. */
    CONST char *name1;		/* Name of variable. */
    CONST char *name2;		/* Second part of variable name. */
    int flags;			/* Information about what happened. */
{
    int *donePtr = (int *) clientData;

    *donePtr = 1;
    return (char *) NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_UpdateObjCmd --
 *
 *	This procedure is invoked to process the "update" Tcl command. See
 *	the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_UpdateObjCmd(clientData, interp, objc, objv)
    ClientData clientData;	/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    int optionIndex;
    int flags = 0;		/* Initialized to avoid compiler warning. */
    static CONST char *updateOptions[] = {"idletasks", (char *) NULL};
    enum updateOptions {REGEXP_IDLETASKS};

    if (objc == 1) {
	flags = TCL_ALL_EVENTS|TCL_DONT_WAIT;
    } else if (objc == 2) {
	if (Tcl_GetIndexFromObj(interp, objv[1], updateOptions,
		"option", 0, &optionIndex) != TCL_OK) {
	    return TCL_ERROR;
	}
	switch ((enum updateOptions) optionIndex) {
	case REGEXP_IDLETASKS:
	    flags = TCL_WINDOW_EVENTS|TCL_IDLE_EVENTS|TCL_DONT_WAIT;
	    break;
	default:
	    Tcl_Panic("Tcl_UpdateObjCmd: bad option index to UpdateOptions");
	}
    } else {
	Tcl_WrongNumArgs(interp, 1, objv, "?idletasks?");
	return TCL_ERROR;
    }
    
    while (Tcl_DoOneEvent(flags) != 0) {
	if (Tcl_LimitExceeded(interp)) {
	    Tcl_ResetResult(interp);
	    Tcl_AppendResult(interp, "limit exceeded", NULL);
	    return TCL_ERROR;
	}
    }

    /*
     * Must clear the interpreter's result because event handlers could have
     * executed commands.
     */

    Tcl_ResetResult(interp);
    return TCL_OK;
}

#ifdef TCL_THREADS
/*
 *-----------------------------------------------------------------------------
 *
 *  NewThreadProc --
 *
 * 	Bootstrap function of a new Tcl thread.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	Initializes Tcl notifier for the current thread.
 *
 *-----------------------------------------------------------------------------
 */

static Tcl_ThreadCreateType
NewThreadProc(ClientData clientData)
{
    ThreadClientData *cdPtr;
    ClientData threadClientData;
    Tcl_ThreadCreateProc *threadProc;

    cdPtr  = (ThreadClientData *)clientData;
    threadProc = cdPtr->proc;
    threadClientData = cdPtr->clientData;
    Tcl_Free((char*)clientData); /* Allocated in Tcl_CreateThread() */

    (*threadProc)(threadClientData);

    TCL_THREAD_CREATE_RETURN;
}
#endif

/*
 *----------------------------------------------------------------------
 *
 * Tcl_CreateThread --
 *
 *	This procedure creates a new thread. This actually belongs to the
 *	tclThread.c file but since we use some private data structures local
 *	to this file, it is placed here.
 *
 * Results:
 *	TCL_OK if the thread could be created.  The thread ID is returned in a
 *	parameter.
 *
 * Side effects:
 *	A new thread is created.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_CreateThread(idPtr, proc, clientData, stackSize, flags)
    Tcl_ThreadId *idPtr;		/* Return, the ID of the thread */
    Tcl_ThreadCreateProc proc;		/* Main() function of the thread */
    ClientData clientData;		/* The one argument to Main() */
    int stackSize;			/* Size of stack for the new thread */
    int flags;				/* Flags controlling behaviour of the
					 * new thread. */
{
#ifdef TCL_THREADS
    ThreadClientData *cdPtr;

    cdPtr = (ThreadClientData *) Tcl_Alloc(sizeof(ThreadClientData));
    cdPtr->proc = proc;
    cdPtr->clientData = clientData;

    return TclpThreadCreate(idPtr, NewThreadProc, (ClientData)cdPtr,
	    stackSize, flags);
#else
    return TCL_ERROR;
#endif /* TCL_THREADS */
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */