shared_source/c_tk_base_7_5_w_mods/tkselect.c

/* $Header$ */

/* 
 * tkSelect.c --
 *
 *      This file manages the selection for the Tk toolkit,
 *      translating between the standard X ICCCM conventions
 *      and Tcl commands.
 *
 * Copyright (c) 1990-1993 The Regents of the University of California.
 * Copyright (c) 1994-1997 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: tkselect.c,v 1.1.1.1 2001/06/13 05:08:09 dtashley Exp $
 */

#include "tkInt.h"
#include "tkSelect.h"

/*
 * When a selection handler is set up by invoking "selection handle",
 * one of the following data structures is set up to hold information
 * about the command to invoke and its interpreter.
 */

typedef struct {
    Tcl_Interp *interp;         /* Interpreter in which to invoke command. */
    int cmdLength;              /* # of non-NULL bytes in command. */
    int charOffset;             /* The offset of the next char to retrieve. */
    int byteOffset;             /* The expected byte offset of the next
                                 * chunk. */
    char buffer[TCL_UTF_MAX];   /* A buffer to hold part of a UTF character
                                 * that is split across chunks.*/
    char command[4];            /* Command to invoke.  Actual space is
                                 * allocated as large as necessary.  This
                                 * must be the last entry in the structure. */
} CommandInfo;

/*
 * When selection ownership is claimed with the "selection own" Tcl command,
 * one of the following structures is created to record the Tcl command
 * to be executed when the selection is lost again.
 */

typedef struct LostCommand {
    Tcl_Interp *interp;         /* Interpreter in which to invoke command. */
    char command[4];            /* Command to invoke.  Actual space is
                                 * allocated as large as necessary.  This
                                 * must be the last entry in the structure. */
} LostCommand;

/*
 * The structure below is used to keep each thread's pending list
 * separate.
 */

typedef struct ThreadSpecificData {
    TkSelInProgress *pendingPtr;
                                /* Topmost search in progress, or
                                 * NULL if none. */
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;

/*
 * Forward declarations for procedures defined in this file:
 */

static int              HandleTclCommand _ANSI_ARGS_((ClientData clientData,
                            int offset, char *buffer, int maxBytes));
static void             LostSelection _ANSI_ARGS_((ClientData clientData));
static int              SelGetProc _ANSI_ARGS_((ClientData clientData,
                            Tcl_Interp *interp, char *portion));

/*
 *--------------------------------------------------------------
 *
 * Tk_CreateSelHandler --
 *
 *      This procedure is called to register a procedure
 *      as the handler for selection requests of a particular
 *      target type on a particular window for a particular
 *      selection.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      In the future, whenever the selection is in tkwin's
 *      window and someone requests the selection in the
 *      form given by target, proc will be invoked to provide
 *      part or all of the selection in the given form.  If
 *      there was already a handler declared for the given
 *      window, target and selection type, then it is replaced.
 *      Proc should have the following form:
 *
 *      int
 *      proc(clientData, offset, buffer, maxBytes)
 *          ClientData clientData;
 *          int offset;
 *          char *buffer;
 *          int maxBytes;
 *      {
 *      }
 *
 *      The clientData argument to proc will be the same as
 *      the clientData argument to this procedure.  The offset
 *      argument indicates which portion of the selection to
 *      return:  skip the first offset bytes.  Buffer is a
 *      pointer to an area in which to place the converted
 *      selection, and maxBytes gives the number of bytes
 *      available at buffer.  Proc should place the selection
 *      in buffer as a string, and return a count of the number
 *      of bytes of selection actually placed in buffer (not
 *      including the terminating NULL character).  If the
 *      return value equals maxBytes, this is a sign that there
 *      is probably still more selection information available.
 *
 *--------------------------------------------------------------
 */

void
Tk_CreateSelHandler(tkwin, selection, target, proc, clientData, format)
    Tk_Window tkwin;            /* Token for window. */
    Atom selection;             /* Selection to be handled. */
    Atom target;                /* The kind of selection conversions
                                 * that can be handled by proc,
                                 * e.g. TARGETS or STRING. */
    Tk_SelectionProc *proc;     /* Procedure to invoke to convert
                                 * selection to type "target". */
    ClientData clientData;      /* Value to pass to proc. */
    Atom format;                /* Format in which the selection
                                 * information should be returned to
                                 * the requestor. XA_STRING is best by
                                 * far, but anything listed in the ICCCM
                                 * will be tolerated (blech). */
{
    register TkSelHandler *selPtr;
    TkWindow *winPtr = (TkWindow *) tkwin;

    if (winPtr->dispPtr->multipleAtom == None) {
        TkSelInit(tkwin);
    }

    /*
     * See if there's already a handler for this target and selection on
     * this window.  If so, re-use it.  If not, create a new one.
     */

    for (selPtr = winPtr->selHandlerList; ; selPtr = selPtr->nextPtr) {
        if (selPtr == NULL) {
            selPtr = (TkSelHandler *) ckalloc(sizeof(TkSelHandler));
            selPtr->nextPtr = winPtr->selHandlerList;
            winPtr->selHandlerList = selPtr;
            break;
        }
        if ((selPtr->selection == selection) && (selPtr->target == target)) {

            /*
             * Special case:  when replacing handler created by
             * "selection handle", free up memory.  Should there be a
             * callback to allow other clients to do this too?
             */

            if (selPtr->proc == HandleTclCommand) {
                ckfree((char *) selPtr->clientData);
            }
            break;
        }
    }
    selPtr->selection = selection;
    selPtr->target = target;
    selPtr->format = format;
    selPtr->proc = proc;
    selPtr->clientData = clientData;
    if (format == XA_STRING) {
        selPtr->size = 8;
    } else {
        selPtr->size = 32;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_DeleteSelHandler --
 *
 *      Remove the selection handler for a given window, target, and
 *      selection, if it exists.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The selection handler for tkwin and target is removed.  If there
 *      is no such handler then nothing happens.
 *
 *----------------------------------------------------------------------
 */

void
Tk_DeleteSelHandler(tkwin, selection, target)
    Tk_Window tkwin;                    /* Token for window. */
    Atom selection;                     /* The selection whose handler
                                         * is to be removed. */
    Atom target;                        /* The target whose selection
                                         * handler is to be removed. */
{
    TkWindow *winPtr = (TkWindow *) tkwin;
    register TkSelHandler *selPtr, *prevPtr;
    register TkSelInProgress *ipPtr;
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

    /*
     * Find the selection handler to be deleted, or return if it doesn't
     * exist.
     */ 

    for (selPtr = winPtr->selHandlerList, prevPtr = NULL; ;
            prevPtr = selPtr, selPtr = selPtr->nextPtr) {
        if (selPtr == NULL) {
            return;
        }
        if ((selPtr->selection == selection) && (selPtr->target == target)) {
            break;
        }
    }

    /*
     * If ConvertSelection is processing this handler, tell it that the
     * handler is dead.
     */

    for (ipPtr = tsdPtr->pendingPtr; ipPtr != NULL; 
            ipPtr = ipPtr->nextPtr) {
        if (ipPtr->selPtr == selPtr) {
            ipPtr->selPtr = NULL;
        }
    }

    /*
     * Free resources associated with the handler.
     */

    if (prevPtr == NULL) {
        winPtr->selHandlerList = selPtr->nextPtr;
    } else {
        prevPtr->nextPtr = selPtr->nextPtr;
    }
    if (selPtr->proc == HandleTclCommand) {
        /*
         * Mark the CommandInfo as deleted and free it if we can.
         */

        ((CommandInfo*)selPtr->clientData)->interp = NULL;
        Tcl_EventuallyFree(selPtr->clientData, Tcl_Free);
    }
    ckfree((char *) selPtr);
}

/*
 *--------------------------------------------------------------
 *
 * Tk_OwnSelection --
 *
 *      Arrange for tkwin to become the owner of a selection.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      From now on, requests for the selection will be directed
 *      to procedures associated with tkwin (they must have been
 *      declared with calls to Tk_CreateSelHandler).  When the
 *      selection is lost by this window, proc will be invoked
 *      (see the manual entry for details).  This procedure may
 *      invoke callbacks, including Tcl scripts, so any calling
 *      function should be reentrant at the point where
 *      Tk_OwnSelection is invoked.
 *
 *--------------------------------------------------------------
 */

void
Tk_OwnSelection(tkwin, selection, proc, clientData)
    Tk_Window tkwin;            /* Window to become new selection
                                 * owner. */
    Atom selection;             /* Selection that window should own. */
    Tk_LostSelProc *proc;       /* Procedure to call when selection
                                 * is taken away from tkwin. */
    ClientData clientData;      /* Arbitrary one-word argument to
                                 * pass to proc. */
{
    register TkWindow *winPtr = (TkWindow *) tkwin;
    TkDisplay *dispPtr = winPtr->dispPtr;
    TkSelectionInfo *infoPtr;
    Tk_LostSelProc *clearProc = NULL;
    ClientData clearData = NULL;        /* Initialization needed only to
                                         * prevent compiler warning. */
    
    
    if (dispPtr->multipleAtom == None) {
        TkSelInit(tkwin);
    }
    Tk_MakeWindowExist(tkwin);

    /*
     * This code is somewhat tricky.  First, we find the specified selection
     * on the selection list.  If the previous owner is in this process, and
     * is a different window, then we need to invoke the clearProc.  However,
     * it's dangerous to call the clearProc right now, because it could
     * invoke a Tcl script that wrecks the current state (e.g. it could
     * delete the window).  To be safe, defer the call until the end of the
     * procedure when we no longer care about the state.
     */

    for (infoPtr = dispPtr->selectionInfoPtr; infoPtr != NULL;
            infoPtr = infoPtr->nextPtr) {
        if (infoPtr->selection == selection) {
            break;
        }
    }
    if (infoPtr == NULL) {
        infoPtr = (TkSelectionInfo*) ckalloc(sizeof(TkSelectionInfo));
        infoPtr->selection = selection;
        infoPtr->nextPtr = dispPtr->selectionInfoPtr;
        dispPtr->selectionInfoPtr = infoPtr;
    } else if (infoPtr->clearProc != NULL) {
        if (infoPtr->owner != tkwin) {
            clearProc = infoPtr->clearProc;
            clearData = infoPtr->clearData;
        } else if (infoPtr->clearProc == LostSelection) {
            /*
             * If the selection handler is one created by "selection own",
             * be sure to free the record for it;  otherwise there will be
             * a memory leak.
             */

            ckfree((char *) infoPtr->clearData);
        }
    }

    infoPtr->owner = tkwin;
    infoPtr->serial = NextRequest(winPtr->display);
    infoPtr->clearProc = proc;
    infoPtr->clearData = clientData;

    /*
     * Note that we are using CurrentTime, even though ICCCM recommends against
     * this practice (the problem is that we don't necessarily have a valid
     * time to use).  We will not be able to retrieve a useful timestamp for
     * the TIMESTAMP target later.
     */

    infoPtr->time = CurrentTime;

    /*
     * Note that we are not checking to see if the selection claim succeeded.
     * If the ownership does not change, then the clearProc may never be
     * invoked, and we will return incorrect information when queried for the
     * current selection owner.
     */

    XSetSelectionOwner(winPtr->display, infoPtr->selection, winPtr->window,
            infoPtr->time);

    /*
     * Now that we are done, we can invoke clearProc without running into
     * reentrancy problems.
     */

    if (clearProc != NULL) {
        (*clearProc)(clearData);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_ClearSelection --
 *
 *      Eliminate the specified selection on tkwin's display, if there is one.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The specified selection is cleared, so that future requests to retrieve
 *      it will fail until some application owns it again.  This procedure
 *      invokes callbacks, possibly including Tcl scripts, so any calling
 *      function should be reentrant at the point Tk_ClearSelection is invoked.
 *
 *----------------------------------------------------------------------
 */

void
Tk_ClearSelection(tkwin, selection)
    Tk_Window tkwin;            /* Window that selects a display. */
    Atom selection;             /* Selection to be cancelled. */
{
    register TkWindow *winPtr = (TkWindow *) tkwin;
    TkDisplay *dispPtr = winPtr->dispPtr;
    TkSelectionInfo *infoPtr;
    TkSelectionInfo *prevPtr;
    TkSelectionInfo *nextPtr;
    Tk_LostSelProc *clearProc = NULL;
    ClientData clearData = NULL;        /* Initialization needed only to
                                         * prevent compiler warning. */

    if (dispPtr->multipleAtom == None) {
        TkSelInit(tkwin);
    }

    for (infoPtr = dispPtr->selectionInfoPtr, prevPtr = NULL;
             infoPtr != NULL; infoPtr = nextPtr) {
        nextPtr = infoPtr->nextPtr;
        if (infoPtr->selection == selection) {
            if (prevPtr == NULL) {
                dispPtr->selectionInfoPtr = nextPtr;
            } else {
                prevPtr->nextPtr = nextPtr;
            }
            break;
        }
        prevPtr = infoPtr;
    }
    
    if (infoPtr != NULL) {
        clearProc = infoPtr->clearProc;
        clearData = infoPtr->clearData;
        ckfree((char *) infoPtr);
    }
    XSetSelectionOwner(winPtr->display, selection, None, CurrentTime);

    if (clearProc != NULL) {
        (*clearProc)(clearData);
    }
}

/*
 *--------------------------------------------------------------
 *
 * Tk_GetSelection --
 *
 *      Retrieve the value of a selection and pass it off (in
 *      pieces, possibly) to a given procedure.
 *
 * Results:
 *      The return value is a standard Tcl return value.
 *      If an error occurs (such as no selection exists)
 *      then an error message is left in the interp's result.
 *
 * Side effects:
 *      The standard X11 protocols are used to retrieve the
 *      selection.  When it arrives, it is passed to proc.  If
 *      the selection is very large, it will be passed to proc
 *      in several pieces.  Proc should have the following
 *      structure:
 *
 *      int
 *      proc(clientData, interp, portion)
 *          ClientData clientData;
 *          Tcl_Interp *interp;
 *          char *portion;
 *      {
 *      }
 *
 *      The interp and clientData arguments to proc will be the
 *      same as the corresponding arguments to Tk_GetSelection.
 *      The portion argument points to a character string
 *      containing part of the selection, and numBytes indicates
 *      the length of the portion, not including the terminating
 *      NULL character.  If the selection arrives in several pieces,
 *      the "portion" arguments in separate calls will contain
 *      successive parts of the selection.  Proc should normally
 *      return TCL_OK.  If it detects an error then it should return
 *      TCL_ERROR and leave an error message in the interp's result; the
 *      remainder of the selection retrieval will be aborted.
 *
 *--------------------------------------------------------------
 */

int
Tk_GetSelection(interp, tkwin, selection, target, proc, clientData)
    Tcl_Interp *interp;         /* Interpreter to use for reporting
                                 * errors. */
    Tk_Window tkwin;            /* Window on whose behalf to retrieve
                                 * the selection (determines display
                                 * from which to retrieve). */
    Atom selection;             /* Selection to retrieve. */
    Atom target;                /* Desired form in which selection
                                 * is to be returned. */
    Tk_GetSelProc *proc;        /* Procedure to call to process the
                                 * selection, once it has been retrieved. */
    ClientData clientData;      /* Arbitrary value to pass to proc. */
{
    TkWindow *winPtr = (TkWindow *) tkwin;
    TkDisplay *dispPtr = winPtr->dispPtr;
    TkSelectionInfo *infoPtr;
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

    if (dispPtr->multipleAtom == None) {
        TkSelInit(tkwin);
    }

    /*
     * If the selection is owned by a window managed by this
     * process, then call the retrieval procedure directly,
     * rather than going through the X server (it's dangerous
     * to go through the X server in this case because it could
     * result in deadlock if an INCR-style selection results).
     */

    for (infoPtr = dispPtr->selectionInfoPtr; infoPtr != NULL;
            infoPtr = infoPtr->nextPtr) {
        if (infoPtr->selection == selection)
            break;
    }
    if (infoPtr != NULL) {
        register TkSelHandler *selPtr;
        int offset, result, count;
        char buffer[TK_SEL_BYTES_AT_ONCE+1];
        TkSelInProgress ip;

        for (selPtr = ((TkWindow *) infoPtr->owner)->selHandlerList;
                selPtr != NULL; selPtr = selPtr->nextPtr) {
            if ((selPtr->target == target)
                    && (selPtr->selection == selection)) {
                break;
            }
        }
        if (selPtr == NULL) {
            Atom type;

            count = TkSelDefaultSelection(infoPtr, target, buffer,
                    TK_SEL_BYTES_AT_ONCE, &type);
            if (count > TK_SEL_BYTES_AT_ONCE) {
                panic("selection handler returned too many bytes");
            }
            if (count < 0) {
                goto cantget;
            }
            buffer[count] = 0;
            result = (*proc)(clientData, interp, buffer);
        } else {
            offset = 0;
            result = TCL_OK;
            ip.selPtr = selPtr;
            ip.nextPtr = tsdPtr->pendingPtr;
            tsdPtr->pendingPtr = &ip;
            while (1) {
                count = (selPtr->proc)(selPtr->clientData, offset, buffer,
                        TK_SEL_BYTES_AT_ONCE);
                if ((count < 0) || (ip.selPtr == NULL)) {
                    tsdPtr->pendingPtr = ip.nextPtr;
                    goto cantget;
                }
                if (count > TK_SEL_BYTES_AT_ONCE) {
                    panic("selection handler returned too many bytes");
                }
                buffer[count] = '\0';
                result = (*proc)(clientData, interp, buffer);
                if ((result != TCL_OK) || (count < TK_SEL_BYTES_AT_ONCE)
                        || (ip.selPtr == NULL)) {
                    break;
                }
                offset += count;
            }
            tsdPtr->pendingPtr = ip.nextPtr;
        }
        return result;
    }

    /*
     * The selection is owned by some other process.
     */

    return TkSelGetSelection(interp, tkwin, selection, target, proc,
            clientData);

    cantget:
    Tcl_AppendResult(interp, Tk_GetAtomName(tkwin, selection),
        " selection doesn't exist or form \"", Tk_GetAtomName(tkwin, target),
        "\" not defined", (char *) NULL);
    return TCL_ERROR;
}

/*
 *--------------------------------------------------------------
 *
 * Tk_SelectionCmd --
 *
 *      This procedure is invoked to process the "selection" Tcl
 *      command.  See the user documentation for details on what
 *      it does.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *--------------------------------------------------------------
 */

int
Tk_SelectionCmd(clientData, interp, argc, argv)
    ClientData clientData;      /* Main window associated with
                                 * interpreter. */
    Tcl_Interp *interp;         /* Current interpreter. */
    int argc;                   /* Number of arguments. */
    char **argv;                /* Argument strings. */
{
    Tk_Window tkwin = (Tk_Window) clientData;
    char *path = NULL;
    Atom selection;
    char *selName = NULL;
    int c, count;
    size_t length;
    char **args;

    if (argc < 2) {
        Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
                " option ?arg arg ...?\"", (char *) NULL);
        return TCL_ERROR;
    }
    c = argv[1][0];
    length = strlen(argv[1]);
    if ((c == 'c') && (strncmp(argv[1], "clear", length) == 0)) {
        for (count = argc-2, args = argv+2; count > 0; count -= 2, args += 2) {
            if (args[0][0] != '-') {
                break;
            }
            if (count < 2) {
                Tcl_AppendResult(interp, "value for \"", *args,
                        "\" missing", (char *) NULL);
                return TCL_ERROR;
            }
            c = args[0][1];
            length = strlen(args[0]);
            if ((c == 'd') && (strncmp(args[0], "-displayof", length) == 0)) {
                path = args[1];
            } else if ((c == 's')
                    && (strncmp(args[0], "-selection", length) == 0)) {
                selName = args[1];
            } else {
                Tcl_AppendResult(interp, "unknown option \"", args[0],
                        "\"", (char *) NULL);
                return TCL_ERROR;
            }
        }
        if (count == 1) {
            path = args[0];
        } else if (count > 1) {
            Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
                    " clear ?options?\"", (char *) NULL);
            return TCL_ERROR;
        }
        if (path != NULL) {
            tkwin = Tk_NameToWindow(interp, path, tkwin);
        }
        if (tkwin == NULL) {
            return TCL_ERROR;
        }
        if (selName != NULL) {
            selection = Tk_InternAtom(tkwin, selName);
        } else {
            selection = XA_PRIMARY;
        }
            
        Tk_ClearSelection(tkwin, selection);
        return TCL_OK;
    } else if ((c == 'g') && (strncmp(argv[1], "get", length) == 0)) {
        Atom target;
        char *targetName = NULL;
        Tcl_DString selBytes;
        int result;
        
        for (count = argc-2, args = argv+2; count > 0; count -= 2, args += 2) {
            if (args[0][0] != '-') {
                break;
            }
            if (count < 2) {
                Tcl_AppendResult(interp, "value for \"", *args,
                        "\" missing", (char *) NULL);
                return TCL_ERROR;
            }
            c = args[0][1];
            length = strlen(args[0]);
            if ((c == 'd') && (strncmp(args[0], "-displayof", length) == 0)) {
                path = args[1];
            } else if ((c == 's')
                    && (strncmp(args[0], "-selection", length) == 0)) {
                selName = args[1];
            } else if ((c == 't')
                    && (strncmp(args[0], "-type", length) == 0)) {
                targetName = args[1];
            } else {
                Tcl_AppendResult(interp, "unknown option \"", args[0],
                        "\"", (char *) NULL);
                return TCL_ERROR;
            }
        }
        if (path != NULL) {
            tkwin = Tk_NameToWindow(interp, path, tkwin);
        }
        if (tkwin == NULL) {
            return TCL_ERROR;
        }
        if (selName != NULL) {
            selection = Tk_InternAtom(tkwin, selName);
        } else {
            selection = XA_PRIMARY;
        }
        if (count > 1) {
            Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
                    " get ?options?\"", (char *) NULL);
            return TCL_ERROR;
        } else if (count == 1) {
            target = Tk_InternAtom(tkwin, args[0]);
        } else if (targetName != NULL) {
            target = Tk_InternAtom(tkwin, targetName);
        } else {
            target = XA_STRING;
        }

        Tcl_DStringInit(&selBytes);
        result = Tk_GetSelection(interp, tkwin, selection, target, SelGetProc,
                (ClientData) &selBytes);
        if (result == TCL_OK) {
            Tcl_DStringResult(interp, &selBytes);
        } else {
            Tcl_DStringFree(&selBytes);
        }
        return result;
    } else if ((c == 'h') && (strncmp(argv[1], "handle", length) == 0)) {
        Atom target, format;
        char *targetName = NULL;
        char *formatName = NULL;
        register CommandInfo *cmdInfoPtr;
        int cmdLength;
        
        for (count = argc-2, args = argv+2; count > 0; count -= 2, args += 2) {
            if (args[0][0] != '-') {
                break;
            }
            if (count < 2) {
                Tcl_AppendResult(interp, "value for \"", *args,
                        "\" missing", (char *) NULL);
                return TCL_ERROR;
            }
            c = args[0][1];
            length = strlen(args[0]);
            if ((c == 'f') && (strncmp(args[0], "-format", length) == 0)) {
                formatName = args[1];
            } else if ((c == 's')
                    && (strncmp(args[0], "-selection", length) == 0)) {
                selName = args[1];
            } else if ((c == 't')
                    && (strncmp(args[0], "-type", length) == 0)) {
                targetName = args[1];
            } else {
                Tcl_AppendResult(interp, "unknown option \"", args[0],
                        "\"", (char *) NULL);
                return TCL_ERROR;
            }
        }

        if ((count < 2) || (count > 4)) {
            Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
                    " handle ?options? window command\"", (char *) NULL);
            return TCL_ERROR;
        }
        tkwin = Tk_NameToWindow(interp, args[0], tkwin);
        if (tkwin == NULL) {
            return TCL_ERROR;
        }
        if (selName != NULL) {
            selection = Tk_InternAtom(tkwin, selName);
        } else {
            selection = XA_PRIMARY;
        }
            
        if (count > 2) {
            target = Tk_InternAtom(tkwin, args[2]);
        } else if (targetName != NULL) {
            target = Tk_InternAtom(tkwin, targetName);
        } else {
            target = XA_STRING;
        }
        if (count > 3) {
            format = Tk_InternAtom(tkwin, args[3]);
        } else if (formatName != NULL) {
            format = Tk_InternAtom(tkwin, formatName);
        } else {
            format = XA_STRING;
        }
        cmdLength = strlen(args[1]);
        if (cmdLength == 0) {
            Tk_DeleteSelHandler(tkwin, selection, target);
        } else {
            cmdInfoPtr = (CommandInfo *) ckalloc((unsigned) (
                    sizeof(CommandInfo) - 3 + cmdLength));
            cmdInfoPtr->interp = interp;
            cmdInfoPtr->charOffset = 0;
            cmdInfoPtr->byteOffset = 0;
            cmdInfoPtr->buffer[0] = '\0';
            cmdInfoPtr->cmdLength = cmdLength;
            strcpy(cmdInfoPtr->command, args[1]);
            Tk_CreateSelHandler(tkwin, selection, target, HandleTclCommand,
                    (ClientData) cmdInfoPtr, format);
        }
        return TCL_OK;
    } else if ((c == 'o') && (strncmp(argv[1], "own", length) == 0)) {
        register LostCommand *lostPtr;
        char *script = NULL;
        int cmdLength;

        for (count = argc-2, args = argv+2; count > 0; count -= 2, args += 2) {
            if (args[0][0] != '-') {
                break;
            }
            if (count < 2) {
                Tcl_AppendResult(interp, "value for \"", *args,
                        "\" missing", (char *) NULL);
                return TCL_ERROR;
            }
            c = args[0][1];
            length = strlen(args[0]);
            if ((c == 'c') && (strncmp(args[0], "-command", length) == 0)) {
                script = args[1];
            } else if ((c == 'd')
                    && (strncmp(args[0], "-displayof", length) == 0)) {
                path = args[1];
            } else if ((c == 's')
                    && (strncmp(args[0], "-selection", length) == 0)) {
                selName = args[1];
            } else {
                Tcl_AppendResult(interp, "unknown option \"", args[0],
                        "\"", (char *) NULL);
                return TCL_ERROR;
            }
        }

        if (count > 2) {
            Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
                    " own ?options? ?window?\"", (char *) NULL);
            return TCL_ERROR;
        }
        if (selName != NULL) {
            selection = Tk_InternAtom(tkwin, selName);
        } else {
            selection = XA_PRIMARY;
        }
        if (count == 0) {
            TkSelectionInfo *infoPtr;
            TkWindow *winPtr;
            if (path != NULL) {
                tkwin = Tk_NameToWindow(interp, path, tkwin);
            }
            if (tkwin == NULL) {
                return TCL_ERROR;
            }
            winPtr = (TkWindow *)tkwin;
            for (infoPtr = winPtr->dispPtr->selectionInfoPtr; infoPtr != NULL;
                    infoPtr = infoPtr->nextPtr) {
                if (infoPtr->selection == selection)
                    break;
            }

            /*
             * Ignore the internal clipboard window.
             */

            if ((infoPtr != NULL)
                    && (infoPtr->owner != winPtr->dispPtr->clipWindow)) {
                Tcl_SetResult(interp, Tk_PathName(infoPtr->owner), TCL_STATIC);
            }
            return TCL_OK;
        }
        tkwin = Tk_NameToWindow(interp, args[0], tkwin);
        if (tkwin == NULL) {
            return TCL_ERROR;
        }
        if (count == 2) {
            script = args[1];
        }
        if (script == NULL) {
            Tk_OwnSelection(tkwin, selection, (Tk_LostSelProc *) NULL,
                    (ClientData) NULL);
            return TCL_OK;
        }
        cmdLength = strlen(script);
        lostPtr = (LostCommand *) ckalloc((unsigned) (sizeof(LostCommand)
                -3 + cmdLength));
        lostPtr->interp = interp;
        strcpy(lostPtr->command, script);
        Tk_OwnSelection(tkwin, selection, LostSelection, (ClientData) lostPtr);
        return TCL_OK;
    } else {
        Tcl_AppendResult(interp, "bad option \"", argv[1],
                "\": must be clear, get, handle, or own", (char *) NULL);
        return TCL_ERROR;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TkSelGetInProgress --
 *
 *      This procedure returns a pointer to the thread-local
 *      list of pending searches.
 *
 * Results:
 *      The return value is a pointer to the first search in progress, 
 *      or NULL if there are none. 
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

TkSelInProgress *
TkSelGetInProgress _ANSI_ARGS_((void))
{
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

    return tsdPtr->pendingPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * TkSelSetInProgress --
 *
 *      This procedure is used to set the thread-local list of pending 
 *      searches.  It is required because the pending list is kept
 *      in thread local storage.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */
void
TkSelSetInProgress(pendingPtr)
    TkSelInProgress *pendingPtr;
{
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

   tsdPtr->pendingPtr = pendingPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * TkSelDeadWindow --
 *
 *      This procedure is invoked just before a TkWindow is deleted.
 *      It performs selection-related cleanup.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Frees up memory associated with the selection.
 *
 *----------------------------------------------------------------------
 */

void
TkSelDeadWindow(winPtr)
    register TkWindow *winPtr;  /* Window that's being deleted. */
{
    register TkSelHandler *selPtr;
    register TkSelInProgress *ipPtr;
    TkSelectionInfo *infoPtr, *prevPtr, *nextPtr;
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

    /*
     * While deleting all the handlers, be careful to check whether
     * ConvertSelection or TkSelPropProc are about to process one of the
     * deleted handlers.
     */

    while (winPtr->selHandlerList != NULL) {
        selPtr = winPtr->selHandlerList;
        winPtr->selHandlerList = selPtr->nextPtr;
        for (ipPtr = tsdPtr->pendingPtr; ipPtr != NULL; 
                ipPtr = ipPtr->nextPtr) {
            if (ipPtr->selPtr == selPtr) {
                ipPtr->selPtr = NULL;
            }
        }
        if (selPtr->proc == HandleTclCommand) {
            /*
             * Mark the CommandInfo as deleted and free it if we can.
             */

            ((CommandInfo*)selPtr->clientData)->interp = NULL;
            Tcl_EventuallyFree(selPtr->clientData, Tcl_Free);
        }
        ckfree((char *) selPtr);
    }

    /*
     * Remove selections owned by window being deleted.
     */

    for (infoPtr = winPtr->dispPtr->selectionInfoPtr, prevPtr = NULL;
             infoPtr != NULL; infoPtr = nextPtr) {
        nextPtr = infoPtr->nextPtr;
        if (infoPtr->owner == (Tk_Window) winPtr) {
            if (infoPtr->clearProc == LostSelection) {
                ckfree((char *) infoPtr->clearData);
            }
            ckfree((char *) infoPtr);
            infoPtr = prevPtr;
            if (prevPtr == NULL) {
                winPtr->dispPtr->selectionInfoPtr = nextPtr;
            } else {
                prevPtr->nextPtr = nextPtr;
            }
        }
        prevPtr = infoPtr;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TkSelInit --
 *
 *      Initialize selection-related information for a display.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Selection-related information is initialized.
 *
 *----------------------------------------------------------------------
 */

void
TkSelInit(tkwin)
    Tk_Window tkwin;            /* Window token (used to find
                                 * display to initialize). */
{
    register TkDisplay *dispPtr = ((TkWindow *) tkwin)->dispPtr;

    /*
     * Fetch commonly-used atoms.
     */

    dispPtr->multipleAtom = Tk_InternAtom(tkwin, "MULTIPLE");
    dispPtr->incrAtom = Tk_InternAtom(tkwin, "INCR");
    dispPtr->targetsAtom = Tk_InternAtom(tkwin, "TARGETS");
    dispPtr->timestampAtom = Tk_InternAtom(tkwin, "TIMESTAMP");
    dispPtr->textAtom = Tk_InternAtom(tkwin, "TEXT");
    dispPtr->compoundTextAtom = Tk_InternAtom(tkwin, "COMPOUND_TEXT");
    dispPtr->applicationAtom = Tk_InternAtom(tkwin, "TK_APPLICATION");
    dispPtr->windowAtom = Tk_InternAtom(tkwin, "TK_WINDOW");
    dispPtr->clipboardAtom = Tk_InternAtom(tkwin, "CLIPBOARD");
}

/*
 *----------------------------------------------------------------------
 *
 * TkSelClearSelection --
 *
 *      This procedure is invoked to process a SelectionClear event.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Invokes the clear procedure for the window which lost the
 *      selection.
 *
 *----------------------------------------------------------------------
 */

void
TkSelClearSelection(tkwin, eventPtr)
    Tk_Window tkwin;            /* Window for which event was targeted. */
    register XEvent *eventPtr;  /* X SelectionClear event. */
{
    register TkWindow *winPtr = (TkWindow *) tkwin;
    TkDisplay *dispPtr = winPtr->dispPtr;
    TkSelectionInfo *infoPtr;
    TkSelectionInfo *prevPtr;

    /*
     * Invoke clear procedure for window that just lost the selection.  This
     * code is a bit tricky, because any callbacks due to selection changes
     * between windows managed by the process have already been made.  Thus,
     * ignore the event unless it refers to the window that's currently the
     * selection owner and the event was generated after the server saw the
     * SetSelectionOwner request.
     */

    for (infoPtr = dispPtr->selectionInfoPtr, prevPtr = NULL;
         infoPtr != NULL; infoPtr = infoPtr->nextPtr) {
        if (infoPtr->selection == eventPtr->xselectionclear.selection) {
            break;
        }
        prevPtr = infoPtr;
    }

    if (infoPtr != NULL && (infoPtr->owner == tkwin)
            && (eventPtr->xselectionclear.serial >= (unsigned) infoPtr->serial)) {
        if (prevPtr == NULL) {
            dispPtr->selectionInfoPtr = infoPtr->nextPtr;
        } else {
            prevPtr->nextPtr = infoPtr->nextPtr;
        }

        /*
         * Because of reentrancy problems, calling clearProc must be done
         * after the infoPtr has been removed from the selectionInfoPtr
         * list (clearProc could modify the list, e.g. by creating
         * a new selection).
         */

        if (infoPtr->clearProc != NULL) {
            (*infoPtr->clearProc)(infoPtr->clearData);
        }
        ckfree((char *) infoPtr);
    }
}

/*
 *--------------------------------------------------------------
 *
 * SelGetProc --
 *
 *      This procedure is invoked to process pieces of the selection
 *      as they arrive during "selection get" commands.
 *
 * Results:
 *      Always returns TCL_OK.
 *
 * Side effects:
 *      Bytes get appended to the dynamic string pointed to by the
 *      clientData argument.
 *
 *--------------------------------------------------------------
 */

        /* ARGSUSED */
static int
SelGetProc(clientData, interp, portion)
    ClientData clientData;      /* Dynamic string holding partially
                                 * assembled selection. */
    Tcl_Interp *interp;         /* Interpreter used for error
                                 * reporting (not used). */
    char *portion;              /* New information to be appended. */
{
    Tcl_DStringAppend((Tcl_DString *) clientData, portion, -1);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * HandleTclCommand --
 *
 *      This procedure acts as selection handler for handlers created
 *      by the "selection handle" command.  It invokes a Tcl command to
 *      retrieve the selection.
 *
 * Results:
 *      The return value is a count of the number of bytes actually
 *      stored at buffer, or -1 if an error occurs while executing
 *      the Tcl command to retrieve the selection.
 *
 * Side effects:
 *      None except for things done by the Tcl command.
 *
 *----------------------------------------------------------------------
 */

static int
HandleTclCommand(clientData, offset, buffer, maxBytes)
    ClientData clientData;      /* Information about command to execute. */
    int offset;                 /* Return selection bytes starting at this
                                 * offset. */
    char *buffer;               /* Place to store converted selection. */
    int maxBytes;               /* Maximum # of bytes to store at buffer. */
{
    CommandInfo *cmdInfoPtr = (CommandInfo *) clientData;
    int spaceNeeded, length;
#define MAX_STATIC_SIZE 100
    char staticSpace[MAX_STATIC_SIZE];
    char *command, *string;
    Tcl_Interp *interp = cmdInfoPtr->interp;
    Tcl_DString oldResult;
    Tcl_Obj *objPtr;
    int extraBytes, charOffset, count, numChars;
    char *p;

    /*
     * We must also protect the interpreter and the command from being
     * deleted too soon.
     */

    Tcl_Preserve(clientData);
    Tcl_Preserve((ClientData) interp);

    /*
     * Compute the proper byte offset in the case where the last chunk
     * split a character.
     */

    if (offset == cmdInfoPtr->byteOffset) {
        charOffset = cmdInfoPtr->charOffset;
        extraBytes = strlen(cmdInfoPtr->buffer);
        if (extraBytes > 0) {
            strcpy(buffer, cmdInfoPtr->buffer);
            maxBytes -= extraBytes;
            buffer += extraBytes;
        }
    } else {
        cmdInfoPtr->byteOffset = 0;
        cmdInfoPtr->charOffset = 0;
        extraBytes = 0;
        charOffset = 0;
    }

    /*
     * First, generate a command by taking the command string
     * and appending the offset and maximum # of bytes.
     */

    spaceNeeded = cmdInfoPtr->cmdLength + 30;
    if (spaceNeeded < MAX_STATIC_SIZE) {
        command = staticSpace;
    } else {
        command = (char *) ckalloc((unsigned) spaceNeeded);
    }
    sprintf(command, "%s %d %d", cmdInfoPtr->command, charOffset, maxBytes);

    /*
     * Execute the command.  Be sure to restore the state of the
     * interpreter after executing the command.
     */

    Tcl_DStringInit(&oldResult);
    Tcl_DStringGetResult(interp, &oldResult);
    if (TkCopyAndGlobalEval(interp, command) == TCL_OK) {
        objPtr = Tcl_GetObjResult(interp);
        string = Tcl_GetStringFromObj(objPtr, &length);
        count = (length > maxBytes) ? maxBytes : length;
        memcpy((VOID *) buffer, (VOID *) string, (size_t) count);
        buffer[count] = '\0';

        /*
         * Update the partial character information for the next
         * retrieval if the command has not been deleted.
         */

        if (cmdInfoPtr->interp != NULL) {
            if (length <= maxBytes) {
                cmdInfoPtr->charOffset += Tcl_NumUtfChars(string, -1);
                cmdInfoPtr->buffer[0] = '\0';
            } else {
                p = string;
                string += count;
                numChars = 0;
                while (p < string) {
                    p = Tcl_UtfNext(p);
                    numChars++;
                }
                cmdInfoPtr->charOffset += numChars;
                length = p - string;
                if (length > 0) {
                    strncpy(cmdInfoPtr->buffer, string, (size_t) length);
                }
                cmdInfoPtr->buffer[length] = '\0';
            }           
            cmdInfoPtr->byteOffset += count + extraBytes;
        }
        count += extraBytes;
    } else {
        count = -1;
    }
    Tcl_DStringResult(interp, &oldResult);

    if (command != staticSpace) {
        ckfree(command);
    }


    Tcl_Release(clientData);
    Tcl_Release((ClientData) interp);
    return count;
}

/*
 *----------------------------------------------------------------------
 *
 * TkSelDefaultSelection --
 *
 *      This procedure is called to generate selection information
 *      for a few standard targets such as TIMESTAMP and TARGETS.
 *      It is invoked only if no handler has been declared by the
 *      application.
 *
 * Results:
 *      If "target" is a standard target understood by this procedure,
 *      the selection is converted to that form and stored as a
 *      character string in buffer.  The type of the selection (e.g.
 *      STRING or ATOM) is stored in *typePtr, and the return value is
 *      a count of the # of non-NULL bytes at buffer.  If the target
 *      wasn't understood, or if there isn't enough space at buffer
 *      to hold the entire selection (no INCR-mode transfers for this
 *      stuff!), then -1 is returned.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
TkSelDefaultSelection(infoPtr, target, buffer, maxBytes, typePtr)
    TkSelectionInfo *infoPtr;   /* Info about selection being retrieved. */
    Atom target;                /* Desired form of selection. */
    char *buffer;               /* Place to put selection characters. */
    int maxBytes;               /* Maximum # of bytes to store at buffer. */
    Atom *typePtr;              /* Store here the type of the selection,
                                 * for use in converting to proper X format. */
{
    register TkWindow *winPtr = (TkWindow *) infoPtr->owner;
    TkDisplay *dispPtr = winPtr->dispPtr;

    if (target == dispPtr->timestampAtom) {
        if (maxBytes < 20) {
            return -1;
        }
        sprintf(buffer, "0x%x", (unsigned int) infoPtr->time);
        *typePtr = XA_INTEGER;
        return strlen(buffer);
    }

    if (target == dispPtr->targetsAtom) {
        register TkSelHandler *selPtr;
        char *atomString;
        int length, atomLength;

        if (maxBytes < 50) {
            return -1;
        }
        strcpy(buffer, "MULTIPLE TARGETS TIMESTAMP TK_APPLICATION TK_WINDOW");
        length = strlen(buffer);
        for (selPtr = winPtr->selHandlerList; selPtr != NULL;
                selPtr = selPtr->nextPtr) {
            if ((selPtr->selection == infoPtr->selection)
                    && (selPtr->target != dispPtr->applicationAtom)
                    && (selPtr->target != dispPtr->windowAtom)) {
                atomString = Tk_GetAtomName((Tk_Window) winPtr,
                        selPtr->target);
                atomLength = strlen(atomString) + 1;
                if ((length + atomLength) >= maxBytes) {
                    return -1;
                }
                sprintf(buffer+length, " %s", atomString);
                length += atomLength;
            }
        }
        *typePtr = XA_ATOM;
        return length;
    }

    if (target == dispPtr->applicationAtom) {
        int length;
        char *name = winPtr->mainPtr->winPtr->nameUid;

        length = strlen(name);
        if (maxBytes <= length) {
            return -1;
        }
        strcpy(buffer, name);
        *typePtr = XA_STRING;
        return length;
    }

    if (target == dispPtr->windowAtom) {
        int length;
        char *name = winPtr->pathName;

        length = strlen(name);
        if (maxBytes <= length) {
            return -1;
        }
        strcpy(buffer, name);
        *typePtr = XA_STRING;
        return length;
    }

    return -1;
}

/*
 *----------------------------------------------------------------------
 *
 * LostSelection --
 *
 *      This procedure is invoked when a window has lost ownership of
 *      the selection and the ownership was claimed with the command
 *      "selection own".
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      A Tcl script is executed;  it can do almost anything.
 *
 *----------------------------------------------------------------------
 */

static void
LostSelection(clientData)
    ClientData clientData;              /* Pointer to LostCommand structure. */
{
    LostCommand *lostPtr = (LostCommand *) clientData;
    Tcl_Obj *objPtr;
    Tcl_Interp *interp;

    interp = lostPtr->interp;
    Tcl_Preserve((ClientData) interp);
    
    /*
     * Execute the command.  Save the interpreter's result, if any, and
     * restore it after executing the command.
     */

    objPtr = Tcl_GetObjResult(interp);
    Tcl_IncrRefCount(objPtr);
    Tcl_ResetResult(interp);

    if (TkCopyAndGlobalEval(interp, lostPtr->command) != TCL_OK) {
        Tcl_BackgroundError(interp);
    }

    Tcl_SetObjResult(interp, objPtr);
    Tcl_DecrRefCount(objPtr);

    Tcl_Release((ClientData) interp);
    
    /*
     * Free the storage for the command, since we're done with it now.
     */

    ckfree((char *) lostPtr);
}

/* End of tkselect.c */