278 lines
7.0 KiB
C
278 lines
7.0 KiB
C
/*
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* tclPreserve.c --
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*
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* This file contains a collection of procedures that are used
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* to make sure that widget records and other data structures
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* aren't reallocated when there are nested procedures that
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* depend on their existence.
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*
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* Copyright (c) 1991-1994 The Regents of the University of California.
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* Copyright (c) 1994-1995 Sun Microsystems, Inc.
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*
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* See the file "license.terms" for information on usage and redistribution
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* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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*
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* SCCS: @(#) tclPreserve.c 1.18 96/08/05 13:15:08
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*/
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#include "tclInt.h"
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/*
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* The following data structure is used to keep track of all the
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* Tcl_Preserve calls that are still in effect. It grows as needed
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* to accommodate any number of calls in effect.
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*/
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typedef struct {
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ClientData clientData; /* Address of preserved block. */
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int refCount; /* Number of Tcl_Preserve calls in effect
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* for block. */
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int mustFree; /* Non-zero means Tcl_EventuallyFree was
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* called while a Tcl_Preserve call was in
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* effect, so the structure must be freed
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* when refCount becomes zero. */
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Tcl_FreeProc *freeProc; /* Procedure to call to free. */
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} Reference;
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static Reference *refArray; /* First in array of references. */
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static int spaceAvl = 0; /* Total number of structures available
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* at *firstRefPtr. */
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static int inUse = 0; /* Count of structures currently in use
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* in refArray. */
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#define INITIAL_SIZE 2
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/*
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* Static routines in this file:
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*/
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static void PreserveExitProc _ANSI_ARGS_((ClientData clientData));
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/*
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*----------------------------------------------------------------------
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*
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* PreserveExitProc --
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*
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* Called during exit processing to clean up the reference array.
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*
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* Results:
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* None.
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*
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* Side effects:
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* Frees the storage of the reference array.
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*
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*----------------------------------------------------------------------
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*/
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/* ARGSUSED */
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static void
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PreserveExitProc(clientData)
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ClientData clientData; /* NULL -Unused. */
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{
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if (spaceAvl != 0) {
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ckfree((char *) refArray);
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refArray = (Reference *) NULL;
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inUse = 0;
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spaceAvl = 0;
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}
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}
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/*
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*----------------------------------------------------------------------
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*
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* Tcl_Preserve --
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*
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* This procedure is used by a procedure to declare its interest
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* in a particular block of memory, so that the block will not be
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* reallocated until a matching call to Tcl_Release has been made.
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*
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* Results:
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* None.
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*
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* Side effects:
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* Information is retained so that the block of memory will
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* not be freed until at least the matching call to Tcl_Release.
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*
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*----------------------------------------------------------------------
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*/
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void
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Tcl_Preserve(clientData)
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ClientData clientData; /* Pointer to malloc'ed block of memory. */
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{
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Reference *refPtr;
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int i;
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/*
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* See if there is already a reference for this pointer. If so,
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* just increment its reference count.
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*/
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for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
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if (refPtr->clientData == clientData) {
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refPtr->refCount++;
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return;
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}
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}
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/*
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* Make a reference array if it doesn't already exist, or make it
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* bigger if it is full.
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*/
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if (inUse == spaceAvl) {
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if (spaceAvl == 0) {
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Tcl_CreateExitHandler((Tcl_ExitProc *) PreserveExitProc,
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(ClientData) NULL);
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refArray = (Reference *) ckalloc((unsigned)
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(INITIAL_SIZE*sizeof(Reference)));
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spaceAvl = INITIAL_SIZE;
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} else {
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Reference *new;
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new = (Reference *) ckalloc((unsigned)
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(2*spaceAvl*sizeof(Reference)));
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memcpy((VOID *) new, (VOID *) refArray,
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spaceAvl*sizeof(Reference));
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ckfree((char *) refArray);
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refArray = new;
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spaceAvl *= 2;
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}
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}
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/*
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* Make a new entry for the new reference.
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*/
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refPtr = &refArray[inUse];
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refPtr->clientData = clientData;
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refPtr->refCount = 1;
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refPtr->mustFree = 0;
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refPtr->freeProc = TCL_STATIC;
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inUse += 1;
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}
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/*
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*----------------------------------------------------------------------
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*
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* Tcl_Release --
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*
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* This procedure is called to cancel a previous call to
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* Tcl_Preserve, thereby allowing a block of memory to be
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* freed (if no one else cares about it).
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*
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* Results:
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* None.
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*
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* Side effects:
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* If Tcl_EventuallyFree has been called for clientData, and if
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* no other call to Tcl_Preserve is still in effect, the block of
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* memory is freed.
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*
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*----------------------------------------------------------------------
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*/
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void
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Tcl_Release(clientData)
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ClientData clientData; /* Pointer to malloc'ed block of memory. */
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{
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Reference *refPtr;
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int mustFree;
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Tcl_FreeProc *freeProc;
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int i;
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for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
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if (refPtr->clientData != clientData) {
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continue;
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}
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refPtr->refCount--;
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if (refPtr->refCount == 0) {
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/*
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* Must remove information from the slot before calling freeProc
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* to avoid reentrancy problems if the freeProc calls Tcl_Preserve
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* on the same clientData. Copy down the last reference in the
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* array to overwrite the current slot.
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*/
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freeProc = refPtr->freeProc;
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mustFree = refPtr->mustFree;
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inUse--;
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if (i < inUse) {
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refArray[i] = refArray[inUse];
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}
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if (mustFree) {
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if ((freeProc == TCL_DYNAMIC) ||
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(freeProc == (Tcl_FreeProc *) free)) {
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ckfree((char *) clientData);
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} else {
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(*freeProc)((char *) clientData);
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}
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}
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}
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return;
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}
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/*
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* Reference not found. This is a bug in the caller.
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*/
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panic("Tcl_Release couldn't find reference for 0x%x", clientData);
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}
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/*
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*----------------------------------------------------------------------
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*
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* Tcl_EventuallyFree --
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*
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* Free up a block of memory, unless a call to Tcl_Preserve is in
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* effect for that block. In this case, defer the free until all
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* calls to Tcl_Preserve have been undone by matching calls to
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* Tcl_Release.
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*
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* Results:
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* None.
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*
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* Side effects:
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* Ptr may be released by calling free().
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*
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*----------------------------------------------------------------------
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*/
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void
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Tcl_EventuallyFree(clientData, freeProc)
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ClientData clientData; /* Pointer to malloc'ed block of memory. */
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Tcl_FreeProc *freeProc; /* Procedure to actually do free. */
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{
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Reference *refPtr;
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int i;
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/*
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* See if there is a reference for this pointer. If so, set its
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* "mustFree" flag (the flag had better not be set already!).
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*/
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for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
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if (refPtr->clientData != clientData) {
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continue;
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}
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if (refPtr->mustFree) {
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panic("Tcl_EventuallyFree called twice for 0x%x\n", clientData);
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}
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refPtr->mustFree = 1;
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refPtr->freeProc = freeProc;
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return;
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}
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/*
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* No reference for this block. Free it now.
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*/
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if ((freeProc == TCL_DYNAMIC)
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|| (freeProc == (Tcl_FreeProc *) free)) {
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ckfree((char *) clientData);
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} else {
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(*freeProc)((char *)clientData);
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}
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}
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