tclio.c

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/* 
 * tclIO.c --
 *
 *	This file provides the generic portions (those that are the same on
 *	all platforms and for all channel types) of Tcl's IO facilities.
 *
 * Copyright (c) 1998-2000 Ajuba Solutions
 * Copyright (c) 1995-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclIO.c,v 1.61 2003/02/19 01:04:57 hobbs Exp $
 */

#include "tclInt.h"
#include "tclPort.h"
#include "tclIO.h"
#include <assert.h>


/*
 * All static variables used in this file are collected into a single
 * instance of the following structure.  For multi-threaded implementations,
 * there is one instance of this structure for each thread.
 *
 * Notice that different structures with the same name appear in other
 * files.  The structure defined below is used in this file only.
 */

typedef struct ThreadSpecificData {

    /*
     * This variable holds the list of nested ChannelHandlerEventProc 
     * invocations.
     */
    NextChannelHandler *nestedHandlerPtr;

    /*
     * List of all channels currently open, indexed by ChannelState,
     * as only one ChannelState exists per set of stacked channels.
     */
    ChannelState *firstCSPtr;
#ifdef oldcode
    /*
     * Has a channel exit handler been created yet?
     */
    int channelExitHandlerCreated;

    /*
     * Has the channel event source been created and registered with the
     * notifier?
     */
    int channelEventSourceCreated;
#endif
    /*
     * Static variables to hold channels for stdin, stdout and stderr.
     */
    Tcl_Channel stdinChannel;
    int stdinInitialized;
    Tcl_Channel stdoutChannel;
    int stdoutInitialized;
    Tcl_Channel stderrChannel;
    int stderrInitialized;

} ThreadSpecificData;

static Tcl_ThreadDataKey dataKey;

/*
 * Static functions in this file:
 */

static ChannelBuffer *	AllocChannelBuffer _ANSI_ARGS_((int length));
static void		ChannelTimerProc _ANSI_ARGS_((
				ClientData clientData));
static int		CheckChannelErrors _ANSI_ARGS_((ChannelState *statePtr,
				int direction));
static int		CheckFlush _ANSI_ARGS_((Channel *chanPtr,
				ChannelBuffer *bufPtr, int newlineFlag));
static int		CheckForDeadChannel _ANSI_ARGS_((Tcl_Interp *interp,
				ChannelState *statePtr));
static void		CheckForStdChannelsBeingClosed _ANSI_ARGS_((
				Tcl_Channel chan));
static void		CleanupChannelHandlers _ANSI_ARGS_((
				Tcl_Interp *interp, Channel *chanPtr));
static int		CloseChannel _ANSI_ARGS_((Tcl_Interp *interp,
				Channel *chanPtr, int errorCode));
static void		CommonGetsCleanup _ANSI_ARGS_((Channel *chanPtr,
				Tcl_Encoding encoding));
static int		CopyAndTranslateBuffer _ANSI_ARGS_((
				ChannelState *statePtr, char *result,
				int space));
static int		CopyBuffer _ANSI_ARGS_((
				Channel *chanPtr, char *result, int space));
static int		CopyData _ANSI_ARGS_((CopyState *csPtr, int mask));
static void		CopyEventProc _ANSI_ARGS_((ClientData clientData,
				int mask));
static void		CreateScriptRecord _ANSI_ARGS_((
				Tcl_Interp *interp, Channel *chanPtr,
				int mask, Tcl_Obj *scriptPtr));
static void		DeleteChannelTable _ANSI_ARGS_((
				ClientData clientData, Tcl_Interp *interp));
static void		DeleteScriptRecord _ANSI_ARGS_((Tcl_Interp *interp,
				Channel *chanPtr, int mask));
static int              DetachChannel _ANSI_ARGS_((Tcl_Interp *interp,
				Tcl_Channel chan));
static void		DiscardInputQueued _ANSI_ARGS_((ChannelState *statePtr,
				int discardSavedBuffers));
static void		DiscardOutputQueued _ANSI_ARGS_((
				ChannelState *chanPtr));
static int		DoRead _ANSI_ARGS_((Channel *chanPtr, char *srcPtr,
				int slen));
static int		DoWrite _ANSI_ARGS_((Channel *chanPtr, CONST char *src,
				int srcLen));
static int		DoReadChars _ANSI_ARGS_ ((Channel* chan,
				Tcl_Obj* objPtr, int toRead, int appendFlag));
static int		DoWriteChars _ANSI_ARGS_ ((Channel* chan,
				CONST char* src, int len));
static int		FilterInputBytes _ANSI_ARGS_((Channel *chanPtr,
				GetsState *statePtr));
static int		FlushChannel _ANSI_ARGS_((Tcl_Interp *interp,
				Channel *chanPtr, int calledFromAsyncFlush));
static Tcl_HashTable *	GetChannelTable _ANSI_ARGS_((Tcl_Interp *interp));
static int		GetInput _ANSI_ARGS_((Channel *chanPtr));
static int		HaveVersion _ANSI_ARGS_((Tcl_ChannelType *typePtr,
				Tcl_ChannelTypeVersion minimumVersion));
static void		PeekAhead _ANSI_ARGS_((Channel *chanPtr,
				char **dstEndPtr, GetsState *gsPtr));
static int		ReadBytes _ANSI_ARGS_((ChannelState *statePtr,
				Tcl_Obj *objPtr, int charsLeft,
				int *offsetPtr));
static int		ReadChars _ANSI_ARGS_((ChannelState *statePtr,
				Tcl_Obj *objPtr, int charsLeft,
				int *offsetPtr, int *factorPtr));
static void		RecycleBuffer _ANSI_ARGS_((ChannelState *statePtr,
				ChannelBuffer *bufPtr, int mustDiscard));
static int		StackSetBlockMode _ANSI_ARGS_((Channel *chanPtr,
				int mode));
static int		SetBlockMode _ANSI_ARGS_((Tcl_Interp *interp,
				Channel *chanPtr, int mode));
static void		StopCopy _ANSI_ARGS_((CopyState *csPtr));
static int		TranslateInputEOL _ANSI_ARGS_((ChannelState *statePtr,
				char *dst, CONST char *src,
				int *dstLenPtr, int *srcLenPtr));
static int		TranslateOutputEOL _ANSI_ARGS_((ChannelState *statePtr,
				char *dst, CONST char *src,
				int *dstLenPtr, int *srcLenPtr));
static void		UpdateInterest _ANSI_ARGS_((Channel *chanPtr));
static int		WriteBytes _ANSI_ARGS_((Channel *chanPtr,
				CONST char *src, int srcLen));
static int		WriteChars _ANSI_ARGS_((Channel *chanPtr,
				CONST char *src, int srcLen));


/*
 *---------------------------------------------------------------------------
 *
 * TclInitIOSubsystem --
 *
 *	Initialize all resources used by this subsystem on a per-process
 *	basis.  
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Depends on the memory subsystems.
 *
 *---------------------------------------------------------------------------
 */

void
TclInitIOSubsystem()
{
    /*
     * By fetching thread local storage we take care of
     * allocating it for each thread.
     */
    (void) TCL_TSD_INIT(&dataKey);
}   

/*
 *-------------------------------------------------------------------------
 *
 * TclFinalizeIOSubsystem --
 *
 *	Releases all resources used by this subsystem on a per-process 
 *	basis.  Closes all extant channels that have not already been 
 *	closed because they were not owned by any interp.  
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Depends on encoding and memory subsystems.
 *
 *-------------------------------------------------------------------------
 */

	/* ARGSUSED */
void
TclFinalizeIOSubsystem()
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    Channel *chanPtr;			/* Iterates over open channels. */
    ChannelState *nextCSPtr;		/* Iterates over open channels. */
    ChannelState *statePtr;		/* state of channel stack */

    for (statePtr = tsdPtr->firstCSPtr; statePtr != (ChannelState *) NULL;
	 statePtr = nextCSPtr) {
	chanPtr		= statePtr->topChanPtr;
        nextCSPtr	= statePtr->nextCSPtr;

        /*
         * Set the channel back into blocking mode to ensure that we wait
         * for all data to flush out.
         */
        
        (void) Tcl_SetChannelOption(NULL, (Tcl_Channel) chanPtr,
                "-blocking", "on");

        if ((chanPtr == (Channel *) tsdPtr->stdinChannel) ||
                (chanPtr == (Channel *) tsdPtr->stdoutChannel) ||
                (chanPtr == (Channel *) tsdPtr->stderrChannel)) {

            /*
             * Decrement the refcount which was earlier artificially bumped
             * up to keep the channel from being closed.
             */

            statePtr->refCount--;
        }

        if (statePtr->refCount <= 0) {

	    /*
             * Close it only if the refcount indicates that the channel is not
             * referenced from any interpreter. If it is, that interpreter will
             * close the channel when it gets destroyed.
             */

            (void) Tcl_Close((Tcl_Interp *) NULL, (Tcl_Channel) chanPtr);

        } else {

            /*
             * The refcount is greater than zero, so flush the channel.
             */

            Tcl_Flush((Tcl_Channel) chanPtr);

            /*
             * Call the device driver to actually close the underlying
             * device for this channel.
             */
            
	    if (chanPtr->typePtr->closeProc != TCL_CLOSE2PROC) {
		(chanPtr->typePtr->closeProc)(chanPtr->instanceData,
			(Tcl_Interp *) NULL);
	    } else {
		(chanPtr->typePtr->close2Proc)(chanPtr->instanceData,
			(Tcl_Interp *) NULL, 0);
	    }

            /*
             * Finally, we clean up the fields in the channel data structure
             * since all of them have been deleted already. We mark the
             * channel with CHANNEL_DEAD to prevent any further IO operations
             * on it.
             */

            chanPtr->instanceData = (ClientData) NULL;
            statePtr->flags |= CHANNEL_DEAD;
        }
    }
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetStdChannel --
 *
 *	This function is used to change the channels that are used
 *	for stdin/stdout/stderr in new interpreters.
 *
 * Results:
 *	None
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SetStdChannel(channel, type)
    Tcl_Channel channel;
    int type;			/* One of TCL_STDIN, TCL_STDOUT, TCL_STDERR. */
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    switch (type) {
	case TCL_STDIN:
	    tsdPtr->stdinInitialized = 1;
	    tsdPtr->stdinChannel = channel;
	    break;
	case TCL_STDOUT:
	    tsdPtr->stdoutInitialized = 1;
	    tsdPtr->stdoutChannel = channel;
	    break;
	case TCL_STDERR:
	    tsdPtr->stderrInitialized = 1;
	    tsdPtr->stderrChannel = channel;
	    break;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetStdChannel --
 *
 *	Returns the specified standard channel.
 *
 * Results:
 *	Returns the specified standard channel, or NULL.
 *
 * Side effects:
 *	May cause the creation of a standard channel and the underlying
 *	file.
 *
 *----------------------------------------------------------------------
 */
Tcl_Channel
Tcl_GetStdChannel(type)
    int type;			/* One of TCL_STDIN, TCL_STDOUT, TCL_STDERR. */
{
    Tcl_Channel channel = NULL;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    /*
     * If the channels were not created yet, create them now and
     * store them in the static variables. 
     */

    switch (type) {
	case TCL_STDIN:
	    if (!tsdPtr->stdinInitialized) {
		tsdPtr->stdinChannel = TclpGetDefaultStdChannel(TCL_STDIN);
		tsdPtr->stdinInitialized = 1;

		/*
                 * Artificially bump the refcount to ensure that the channel
                 * is only closed on exit.
                 *
                 * NOTE: Must only do this if stdinChannel is not NULL. It
                 * can be NULL in situations where Tcl is unable to connect
                 * to the standard input.
                 */

                if (tsdPtr->stdinChannel != (Tcl_Channel) NULL) {
                    (void) Tcl_RegisterChannel((Tcl_Interp *) NULL,
                            tsdPtr->stdinChannel);
                }
	    }
	    channel = tsdPtr->stdinChannel;
	    break;
	case TCL_STDOUT:
	    if (!tsdPtr->stdoutInitialized) {
		tsdPtr->stdoutChannel = TclpGetDefaultStdChannel(TCL_STDOUT);
		tsdPtr->stdoutInitialized = 1;
                if (tsdPtr->stdoutChannel != (Tcl_Channel) NULL) {
                    (void) Tcl_RegisterChannel((Tcl_Interp *) NULL,
                            tsdPtr->stdoutChannel);
                }
	    }
	    channel = tsdPtr->stdoutChannel;
	    break;
	case TCL_STDERR:
	    if (!tsdPtr->stderrInitialized) {
		tsdPtr->stderrChannel = TclpGetDefaultStdChannel(TCL_STDERR);
		tsdPtr->stderrInitialized = 1;
                if (tsdPtr->stderrChannel != (Tcl_Channel) NULL) {
                    (void) Tcl_RegisterChannel((Tcl_Interp *) NULL,
                            tsdPtr->stderrChannel);
                }
	    }
	    channel = tsdPtr->stderrChannel;
	    break;
    }
    return channel;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_CreateCloseHandler
 *
 *	Creates a close callback which will be called when the channel is
 *	closed.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Causes the callback to be called in the future when the channel
 *	will be closed.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_CreateCloseHandler(chan, proc, clientData)
    Tcl_Channel chan;		/* The channel for which to create the
                                 * close callback. */
    Tcl_CloseProc *proc;	/* The callback routine to call when the
                                 * channel will be closed. */
    ClientData clientData;	/* Arbitrary data to pass to the
                                 * close callback. */
{