shared_source/c_tcl_base_7_5_w_mods/tclpreserve.c

/* $Header$ */
/* 
 * tclPreserve.c --
 *
 *      This file contains a collection of procedures that are used
 *      to make sure that widget records and other data structures
 *      aren't reallocated when there are nested procedures that
 *      depend on their existence.
 *
 * Copyright (c) 1991-1994 The Regents of the University of California.
 * Copyright (c) 1994-1998 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: tclpreserve.c,v 1.1.1.1 2001/06/13 04:45:15 dtashley Exp $
 */

#include "tclInt.h"

/*
 * The following data structure is used to keep track of all the
 * Tcl_Preserve calls that are still in effect.  It grows as needed
 * to accommodate any number of calls in effect.
 */

typedef struct {
    ClientData clientData;      /* Address of preserved block. */
    int refCount;               /* Number of Tcl_Preserve calls in effect
                                 * for block. */
    int mustFree;               /* Non-zero means Tcl_EventuallyFree was
                                 * called while a Tcl_Preserve call was in
                                 * effect, so the structure must be freed
                                 * when refCount becomes zero. */
    Tcl_FreeProc *freeProc;     /* Procedure to call to free. */
} Reference;

static Reference *refArray;     /* First in array of references. */
static int spaceAvl = 0;        /* Total number of structures available
                                 * at *firstRefPtr. */
static int inUse = 0;           /* Count of structures currently in use
                                 * in refArray. */
#define INITIAL_SIZE 2
TCL_DECLARE_MUTEX(preserveMutex)/* To protect the above statics */

/*
 * The following data structure is used to keep track of whether an
 * arbitrary block of memory has been deleted.  This is used by the
 * TclHandle code to avoid the more time-expensive algorithm of
 * Tcl_Preserve().  This mechanism is mainly used when we have lots of
 * references to a few big, expensive objects that we don't want to live
 * any longer than necessary.
 */

typedef struct HandleStruct {
    VOID *ptr;                  /* Pointer to the memory block being
                                 * tracked.  This field will become NULL when
                                 * the memory block is deleted.  This field
                                 * must be the first in the structure. */
#ifdef TCL_MEM_DEBUG
    VOID *ptr2;                 /* Backup copy of the abpve pointer used to
                                 * ensure that the contents of the handle are
                                 * not changed by anyone else. */
#endif
    int refCount;               /* Number of TclHandlePreserve() calls in
                                 * effect on this handle. */
} HandleStruct;


/*
 * Static routines in this file:
 */

static void     PreserveExitProc _ANSI_ARGS_((ClientData clientData));


/*
 *----------------------------------------------------------------------
 *
 * PreserveExitProc --
 *
 *      Called during exit processing to clean up the reference array.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Frees the storage of the reference array.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
static void
PreserveExitProc(clientData)
    ClientData clientData;              /* NULL -Unused. */
{
    Tcl_MutexLock(&preserveMutex);
    if (spaceAvl != 0) {
        ckfree((char *) refArray);
        refArray = (Reference *) NULL;
        inUse = 0;
        spaceAvl = 0;
    }
    Tcl_MutexUnlock(&preserveMutex);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Preserve --
 *
 *      This procedure is used by a procedure to declare its interest
 *      in a particular block of memory, so that the block will not be
 *      reallocated until a matching call to Tcl_Release has been made.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Information is retained so that the block of memory will
 *      not be freed until at least the matching call to Tcl_Release.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_Preserve(clientData)
    ClientData clientData;      /* Pointer to malloc'ed block of memory. */
{
    Reference *refPtr;
    int i;

    /*
     * See if there is already a reference for this pointer.  If so,
     * just increment its reference count.
     */

    Tcl_MutexLock(&preserveMutex);
    for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
        if (refPtr->clientData == clientData) {
            refPtr->refCount++;
            Tcl_MutexUnlock(&preserveMutex);
            return;
        }
    }

    /*
     * Make a reference array if it doesn't already exist, or make it
     * bigger if it is full.
     */

    if (inUse == spaceAvl) {
        if (spaceAvl == 0) {
            Tcl_CreateExitHandler((Tcl_ExitProc *) PreserveExitProc,
                    (ClientData) NULL);
            refArray = (Reference *) ckalloc((unsigned)
                    (INITIAL_SIZE*sizeof(Reference)));
            spaceAvl = INITIAL_SIZE;
        } else {
            Reference *new;

            new = (Reference *) ckalloc((unsigned)
                    (2*spaceAvl*sizeof(Reference)));
            memcpy((VOID *) new, (VOID *) refArray,
                    spaceAvl*sizeof(Reference));
            ckfree((char *) refArray);
            refArray = new;
            spaceAvl *= 2;
        }
    }

    /*
     * Make a new entry for the new reference.
     */

    refPtr = &refArray[inUse];
    refPtr->clientData = clientData;
    refPtr->refCount = 1;
    refPtr->mustFree = 0;
    refPtr->freeProc = TCL_STATIC;
    inUse += 1;
    Tcl_MutexUnlock(&preserveMutex);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Release --
 *
 *      This procedure is called to cancel a previous call to
 *      Tcl_Preserve, thereby allowing a block of memory to be
 *      freed (if no one else cares about it).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If Tcl_EventuallyFree has been called for clientData, and if
 *      no other call to Tcl_Preserve is still in effect, the block of
 *      memory is freed.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_Release(clientData)
    ClientData clientData;      /* Pointer to malloc'ed block of memory. */
{
    Reference *refPtr;
    int mustFree;
    Tcl_FreeProc *freeProc;
    int i;

    Tcl_MutexLock(&preserveMutex);
    for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
        if (refPtr->clientData != clientData) {
            continue;
        }
        refPtr->refCount--;
        if (refPtr->refCount == 0) {

            /*
             * Must remove information from the slot before calling freeProc
             * to avoid reentrancy problems if the freeProc calls Tcl_Preserve
             * on the same clientData. Copy down the last reference in the
             * array to overwrite the current slot.
             */

            freeProc = refPtr->freeProc;
            mustFree = refPtr->mustFree;
            inUse--;
            if (i < inUse) {
                refArray[i] = refArray[inUse];
            }
            if (mustFree) {
                if ((freeProc == TCL_DYNAMIC) ||
                        (freeProc == (Tcl_FreeProc *) free)) {
                    ckfree((char *) clientData);
                } else {
                    Tcl_MutexUnlock(&preserveMutex);
                    (*freeProc)((char *) clientData);
                    return;
                }
            }
        }
        Tcl_MutexUnlock(&preserveMutex);
        return;
    }
    Tcl_MutexUnlock(&preserveMutex);

    /*
     * Reference not found.  This is a bug in the caller.
     */

    panic("Tcl_Release couldn't find reference for 0x%x", clientData);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_EventuallyFree --
 *
 *      Free up a block of memory, unless a call to Tcl_Preserve is in
 *      effect for that block.  In this case, defer the free until all
 *      calls to Tcl_Preserve have been undone by matching calls to
 *      Tcl_Release.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Ptr may be released by calling free().
 *
 *----------------------------------------------------------------------
 */

void
Tcl_EventuallyFree(clientData, freeProc)
    ClientData clientData;      /* Pointer to malloc'ed block of memory. */
    Tcl_FreeProc *freeProc;     /* Procedure to actually do free. */
{
    Reference *refPtr;
    int i;

    /*
     * See if there is a reference for this pointer.  If so, set its
     * "mustFree" flag (the flag had better not be set already!).
     */

    Tcl_MutexLock(&preserveMutex);
    for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
        if (refPtr->clientData != clientData) {
            continue;
        }
        if (refPtr->mustFree) {
            panic("Tcl_EventuallyFree called twice for 0x%x\n", clientData);
        }
        refPtr->mustFree = 1;
        refPtr->freeProc = freeProc;
        Tcl_MutexUnlock(&preserveMutex);
        return;
    }
    Tcl_MutexUnlock(&preserveMutex);

    /*
     * No reference for this block.  Free it now.
     */

    if ((freeProc == TCL_DYNAMIC)
            || (freeProc == (Tcl_FreeProc *) free)) {
        ckfree((char *) clientData);
    } else {
        (*freeProc)((char *)clientData);
    }
}

/*
 *---------------------------------------------------------------------------
 *
 * TclHandleCreate --
 *
 *      Allocate a handle that contains enough information to determine
 *      if an arbitrary malloc'd block has been deleted.  This is 
 *      used to avoid the more time-expensive algorithm of Tcl_Preserve().
 *
 * Results:
 *      The return value is a TclHandle that refers to the given malloc'd
 *      block.  Doubly dereferencing the returned handle will give
 *      back the pointer to the block, or will give NULL if the block has
 *      been deleted.
 *
 * Side effects:
 *      The caller must keep track of this handle (generally by storing
 *      it in a field in the malloc'd block) and call TclHandleFree()
 *      on this handle when the block is deleted.  Everything else that
 *      wishes to keep track of whether the malloc'd block has been deleted
 *      should use calls to TclHandlePreserve() and TclHandleRelease()
 *      on the associated handle.
 *
 *---------------------------------------------------------------------------
 */

TclHandle
TclHandleCreate(ptr)
    VOID *ptr;                  /* Pointer to an arbitrary block of memory
                                 * to be tracked for deletion.  Must not be
                                 * NULL. */
{
    HandleStruct *handlePtr;

    handlePtr = (HandleStruct *) ckalloc(sizeof(HandleStruct));
    handlePtr->ptr = ptr;
#ifdef TCL_MEM_DEBUG
    handlePtr->ptr2 = ptr;
#endif
    handlePtr->refCount = 0;
    return (TclHandle) handlePtr;
}

/*
 *---------------------------------------------------------------------------
 *
 * TclHandleFree --
 *
 *      Called when the arbitrary malloc'd block associated with the
 *      handle is being deleted.  Modifies the handle so that doubly
 *      dereferencing it will give NULL.  This informs any user of the
 *      handle that the block of memory formerly referenced by the
 *      handle has been freed.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If nothing is referring to the handle, the handle will be reclaimed.
 *
 *---------------------------------------------------------------------------
 */

void
TclHandleFree(handle)
    TclHandle handle;           /* Previously created handle associated
                                 * with a malloc'd block that is being
                                 * deleted.  The handle is modified so that
                                 * doubly dereferencing it will give NULL. */
{
    HandleStruct *handlePtr;

    handlePtr = (HandleStruct *) handle;
#ifdef TCL_MEM_DEBUG
    if (handlePtr->refCount == 0x61616161) {
        panic("using previously disposed TclHandle %x", handlePtr);
    }
    if (handlePtr->ptr2 != handlePtr->ptr) {
        panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
                handlePtr, handlePtr->ptr2, handlePtr->ptr);
    }
#endif
    handlePtr->ptr = NULL;
    if (handlePtr->refCount == 0) {
        ckfree((char *) handlePtr);
    }
}

/*
 *---------------------------------------------------------------------------
 *
 * TclHandlePreserve --
 *
 *      Declare an interest in the arbitrary malloc'd block associated
 *      with the handle.  
 *
 * Results:
 *      The return value is the handle argument, with its ref count
 *      incremented.
 *
 * Side effects:
 *      For each call to TclHandlePreserve(), there should be a matching
 *      call to TclHandleRelease() when the caller is no longer interested
 *      in the malloc'd block associated with the handle.
 *
 *---------------------------------------------------------------------------
 */

TclHandle
TclHandlePreserve(handle)
    TclHandle handle;           /* Declare an interest in the block of
                                 * memory referenced by this handle. */
{
    HandleStruct *handlePtr;

    handlePtr = (HandleStruct *) handle;
#ifdef TCL_MEM_DEBUG
    if (handlePtr->refCount == 0x61616161) {
        panic("using previously disposed TclHandle %x", handlePtr);
    }
    if ((handlePtr->ptr != NULL)
            && (handlePtr->ptr != handlePtr->ptr2)) {
        panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
                handlePtr, handlePtr->ptr2, handlePtr->ptr);
    }
#endif
    handlePtr->refCount++;

    return handle;
}

/*
 *---------------------------------------------------------------------------
 *
 * TclHandleRelease --
 *
 *      This procedure is called to release an interest in the malloc'd
 *      block associated with the handle.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The ref count of the handle is decremented.  If the malloc'd block
 *      has been freed and if no one is using the handle any more, the
 *      handle will be reclaimed.
 *
 *---------------------------------------------------------------------------
 */
 
void
TclHandleRelease(handle)
    TclHandle handle;           /* Unregister interest in the block of
                                 * memory referenced by this handle. */
{
    HandleStruct *handlePtr;

    handlePtr = (HandleStruct *) handle;
#ifdef TCL_MEM_DEBUG
    if (handlePtr->refCount == 0x61616161) {
        panic("using previously disposed TclHandle %x", handlePtr);
    }
    if ((handlePtr->ptr != NULL)
            && (handlePtr->ptr != handlePtr->ptr2)) {
        panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
                handlePtr, handlePtr->ptr2, handlePtr->ptr);
    }
#endif
    handlePtr->refCount--;
    if ((handlePtr->refCount == 0) && (handlePtr->ptr == NULL)) {
        ckfree((char *) handlePtr);
    }
}
    
/* End of tclpreserve.c */
1	dashley	71	/* $Header$ */
2			/*
3			* tclPreserve.c --
4			*
5			* This file contains a collection of procedures that are used
6			* to make sure that widget records and other data structures
7			* aren't reallocated when there are nested procedures that
8			* depend on their existence.
9			*
10			* Copyright (c) 1991-1994 The Regents of the University of California.
11			* Copyright (c) 1994-1998 Sun Microsystems, Inc.
12			*
13			* See the file "license.terms" for information on usage and redistribution
14			* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
15			*
16			* RCS: @(#) $Id: tclpreserve.c,v 1.1.1.1 2001/06/13 04:45:15 dtashley Exp $
17			*/
18
19			#include "tclInt.h"
20
21			/*
22			* The following data structure is used to keep track of all the
23			* Tcl_Preserve calls that are still in effect. It grows as needed
24			* to accommodate any number of calls in effect.
25			*/
26
27			typedef struct {
28			ClientData clientData; /* Address of preserved block. */
29			int refCount; /* Number of Tcl_Preserve calls in effect
30			* for block. */
31			int mustFree; /* Non-zero means Tcl_EventuallyFree was
32			* called while a Tcl_Preserve call was in
33			* effect, so the structure must be freed
34			* when refCount becomes zero. */
35			Tcl_FreeProc freeProc; / Procedure to call to free. */
36			} Reference;
37
38			static Reference refArray; / First in array of references. */
39			static int spaceAvl = 0; /* Total number of structures available
40			* at firstRefPtr. /
41			static int inUse = 0; /* Count of structures currently in use
42			* in refArray. */
43			#define INITIAL_SIZE 2
44			TCL_DECLARE_MUTEX(preserveMutex)/* To protect the above statics */
45
46			/*
47			* The following data structure is used to keep track of whether an
48			* arbitrary block of memory has been deleted. This is used by the
49			* TclHandle code to avoid the more time-expensive algorithm of
50			* Tcl_Preserve(). This mechanism is mainly used when we have lots of
51			* references to a few big, expensive objects that we don't want to live
52			* any longer than necessary.
53			*/
54
55			typedef struct HandleStruct {
56			VOID ptr; / Pointer to the memory block being
57			* tracked. This field will become NULL when
58			* the memory block is deleted. This field
59			* must be the first in the structure. */
60			#ifdef TCL_MEM_DEBUG
61			VOID ptr2; / Backup copy of the abpve pointer used to
62			* ensure that the contents of the handle are
63			* not changed by anyone else. */
64			#endif
65			int refCount; /* Number of TclHandlePreserve() calls in
66			* effect on this handle. */
67			} HandleStruct;
68
69
70			/*
71			* Static routines in this file:
72			*/
73
74			static void PreserveExitProc _ANSI_ARGS_((ClientData clientData));
75
76
77			/*
78			*----------------------------------------------------------------------
79			*
80			* PreserveExitProc --
81			*
82			* Called during exit processing to clean up the reference array.
83			*
84			* Results:
85			* None.
86			*
87			* Side effects:
88			* Frees the storage of the reference array.
89			*
90			*----------------------------------------------------------------------
91			*/
92
93			/* ARGSUSED */
94			static void
95			PreserveExitProc(clientData)
96			ClientData clientData; /* NULL -Unused. */
97			{
98			Tcl_MutexLock(&preserveMutex);
99			if (spaceAvl != 0) {
100			ckfree((char *) refArray);
101			refArray = (Reference *) NULL;
102			inUse = 0;
103			spaceAvl = 0;
104			}
105			Tcl_MutexUnlock(&preserveMutex);
106			}
107
108			/*
109			*----------------------------------------------------------------------
110			*
111			* Tcl_Preserve --
112			*
113			* This procedure is used by a procedure to declare its interest
114			* in a particular block of memory, so that the block will not be
115			* reallocated until a matching call to Tcl_Release has been made.
116			*
117			* Results:
118			* None.
119			*
120			* Side effects:
121			* Information is retained so that the block of memory will
122			* not be freed until at least the matching call to Tcl_Release.
123			*
124			*----------------------------------------------------------------------
125			*/
126
127			void
128			Tcl_Preserve(clientData)
129			ClientData clientData; /* Pointer to malloc'ed block of memory. */
130			{
131			Reference *refPtr;
132			int i;
133
134			/*
135			* See if there is already a reference for this pointer. If so,
136			* just increment its reference count.
137			*/
138
139			Tcl_MutexLock(&preserveMutex);
140			for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
141			if (refPtr->clientData == clientData) {
142			refPtr->refCount++;
143			Tcl_MutexUnlock(&preserveMutex);
144			return;
145			}
146			}
147
148			/*
149			* Make a reference array if it doesn't already exist, or make it
150			* bigger if it is full.
151			*/
152
153			if (inUse == spaceAvl) {
154			if (spaceAvl == 0) {
155			Tcl_CreateExitHandler((Tcl_ExitProc *) PreserveExitProc,
156			(ClientData) NULL);
157			refArray = (Reference *) ckalloc((unsigned)
158			(INITIAL_SIZE*sizeof(Reference)));
159			spaceAvl = INITIAL_SIZE;
160			} else {
161			Reference *new;
162
163			new = (Reference *) ckalloc((unsigned)
164			(2spaceAvlsizeof(Reference)));
165			memcpy((VOID ) new, (VOID ) refArray,
166			spaceAvl*sizeof(Reference));
167			ckfree((char *) refArray);
168			refArray = new;
169			spaceAvl *= 2;
170			}
171			}
172
173			/*
174			* Make a new entry for the new reference.
175			*/
176
177			refPtr = &refArray[inUse];
178			refPtr->clientData = clientData;
179			refPtr->refCount = 1;
180			refPtr->mustFree = 0;
181			refPtr->freeProc = TCL_STATIC;
182			inUse += 1;
183			Tcl_MutexUnlock(&preserveMutex);
184			}
185
186			/*
187			*----------------------------------------------------------------------
188			*
189			* Tcl_Release --
190			*
191			* This procedure is called to cancel a previous call to
192			* Tcl_Preserve, thereby allowing a block of memory to be
193			* freed (if no one else cares about it).
194			*
195			* Results:
196			* None.
197			*
198			* Side effects:
199			* If Tcl_EventuallyFree has been called for clientData, and if
200			* no other call to Tcl_Preserve is still in effect, the block of
201			* memory is freed.
202			*
203			*----------------------------------------------------------------------
204			*/
205
206			void
207			Tcl_Release(clientData)
208			ClientData clientData; /* Pointer to malloc'ed block of memory. */
209			{
210			Reference *refPtr;
211			int mustFree;
212			Tcl_FreeProc *freeProc;
213			int i;
214
215			Tcl_MutexLock(&preserveMutex);
216			for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
217			if (refPtr->clientData != clientData) {
218			continue;
219			}
220			refPtr->refCount--;
221			if (refPtr->refCount == 0) {
222
223			/*
224			* Must remove information from the slot before calling freeProc
225			* to avoid reentrancy problems if the freeProc calls Tcl_Preserve
226			* on the same clientData. Copy down the last reference in the
227			* array to overwrite the current slot.
228			*/
229
230			freeProc = refPtr->freeProc;
231			mustFree = refPtr->mustFree;
232			inUse--;
233			if (i < inUse) {
234			refArray[i] = refArray[inUse];
235			}
236			if (mustFree) {
237			if ((freeProc == TCL_DYNAMIC) \|\|
238			(freeProc == (Tcl_FreeProc *) free)) {
239			ckfree((char *) clientData);
240			} else {
241			Tcl_MutexUnlock(&preserveMutex);
242			(freeProc)((char ) clientData);
243			return;
244			}
245			}
246			}
247			Tcl_MutexUnlock(&preserveMutex);
248			return;
249			}
250			Tcl_MutexUnlock(&preserveMutex);
251
252			/*
253			* Reference not found. This is a bug in the caller.
254			*/
255
256			panic("Tcl_Release couldn't find reference for 0x%x", clientData);
257			}
258
259			/*
260			*----------------------------------------------------------------------
261			*
262			* Tcl_EventuallyFree --
263			*
264			* Free up a block of memory, unless a call to Tcl_Preserve is in
265			* effect for that block. In this case, defer the free until all
266			* calls to Tcl_Preserve have been undone by matching calls to
267			* Tcl_Release.
268			*
269			* Results:
270			* None.
271			*
272			* Side effects:
273			* Ptr may be released by calling free().
274			*
275			*----------------------------------------------------------------------
276			*/
277
278			void
279			Tcl_EventuallyFree(clientData, freeProc)
280			ClientData clientData; /* Pointer to malloc'ed block of memory. */
281			Tcl_FreeProc freeProc; / Procedure to actually do free. */
282			{
283			Reference *refPtr;
284			int i;
285
286			/*
287			* See if there is a reference for this pointer. If so, set its
288			* "mustFree" flag (the flag had better not be set already!).
289			*/
290
291			Tcl_MutexLock(&preserveMutex);
292			for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
293			if (refPtr->clientData != clientData) {
294			continue;
295			}
296			if (refPtr->mustFree) {
297			panic("Tcl_EventuallyFree called twice for 0x%x\n", clientData);
298			}
299			refPtr->mustFree = 1;
300			refPtr->freeProc = freeProc;
301			Tcl_MutexUnlock(&preserveMutex);
302			return;
303			}
304			Tcl_MutexUnlock(&preserveMutex);
305
306			/*
307			* No reference for this block. Free it now.
308			*/
309
310			if ((freeProc == TCL_DYNAMIC)
311			\|\| (freeProc == (Tcl_FreeProc *) free)) {
312			ckfree((char *) clientData);
313			} else {
314			(freeProc)((char )clientData);
315			}
316			}
317
318			/*
319			*---------------------------------------------------------------------------
320			*
321			* TclHandleCreate --
322			*
323			* Allocate a handle that contains enough information to determine
324			* if an arbitrary malloc'd block has been deleted. This is
325			* used to avoid the more time-expensive algorithm of Tcl_Preserve().
326			*
327			* Results:
328			* The return value is a TclHandle that refers to the given malloc'd
329			* block. Doubly dereferencing the returned handle will give
330			* back the pointer to the block, or will give NULL if the block has
331			* been deleted.
332			*
333			* Side effects:
334			* The caller must keep track of this handle (generally by storing
335			* it in a field in the malloc'd block) and call TclHandleFree()
336			* on this handle when the block is deleted. Everything else that
337			* wishes to keep track of whether the malloc'd block has been deleted
338			* should use calls to TclHandlePreserve() and TclHandleRelease()
339			* on the associated handle.
340			*
341			*---------------------------------------------------------------------------
342			*/
343
344			TclHandle
345			TclHandleCreate(ptr)
346			VOID ptr; / Pointer to an arbitrary block of memory
347			* to be tracked for deletion. Must not be
348			* NULL. */
349			{
350			HandleStruct *handlePtr;
351
352			handlePtr = (HandleStruct *) ckalloc(sizeof(HandleStruct));
353			handlePtr->ptr = ptr;
354			#ifdef TCL_MEM_DEBUG
355			handlePtr->ptr2 = ptr;
356			#endif
357			handlePtr->refCount = 0;
358			return (TclHandle) handlePtr;
359			}
360
361			/*
362			*---------------------------------------------------------------------------
363			*
364			* TclHandleFree --
365			*
366			* Called when the arbitrary malloc'd block associated with the
367			* handle is being deleted. Modifies the handle so that doubly
368			* dereferencing it will give NULL. This informs any user of the
369			* handle that the block of memory formerly referenced by the
370			* handle has been freed.
371			*
372			* Results:
373			* None.
374			*
375			* Side effects:
376			* If nothing is referring to the handle, the handle will be reclaimed.
377			*
378			*---------------------------------------------------------------------------
379			*/
380
381			void
382			TclHandleFree(handle)
383			TclHandle handle; /* Previously created handle associated
384			* with a malloc'd block that is being
385			* deleted. The handle is modified so that
386			* doubly dereferencing it will give NULL. */
387			{
388			HandleStruct *handlePtr;
389
390			handlePtr = (HandleStruct *) handle;
391			#ifdef TCL_MEM_DEBUG
392			if (handlePtr->refCount == 0x61616161) {
393			panic("using previously disposed TclHandle %x", handlePtr);
394			}
395			if (handlePtr->ptr2 != handlePtr->ptr) {
396			panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
397			handlePtr, handlePtr->ptr2, handlePtr->ptr);
398			}
399			#endif
400			handlePtr->ptr = NULL;
401			if (handlePtr->refCount == 0) {
402			ckfree((char *) handlePtr);
403			}
404			}
405
406			/*
407			*---------------------------------------------------------------------------
408			*
409			* TclHandlePreserve --
410			*
411			* Declare an interest in the arbitrary malloc'd block associated
412			* with the handle.
413			*
414			* Results:
415			* The return value is the handle argument, with its ref count
416			* incremented.
417			*
418			* Side effects:
419			* For each call to TclHandlePreserve(), there should be a matching
420			* call to TclHandleRelease() when the caller is no longer interested
421			* in the malloc'd block associated with the handle.
422			*
423			*---------------------------------------------------------------------------
424			*/
425
426			TclHandle
427			TclHandlePreserve(handle)
428			TclHandle handle; /* Declare an interest in the block of
429			* memory referenced by this handle. */
430			{
431			HandleStruct *handlePtr;
432
433			handlePtr = (HandleStruct *) handle;
434			#ifdef TCL_MEM_DEBUG
435			if (handlePtr->refCount == 0x61616161) {
436			panic("using previously disposed TclHandle %x", handlePtr);
437			}
438			if ((handlePtr->ptr != NULL)
439			&& (handlePtr->ptr != handlePtr->ptr2)) {
440			panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
441			handlePtr, handlePtr->ptr2, handlePtr->ptr);
442			}
443			#endif
444			handlePtr->refCount++;
445
446			return handle;
447			}
448
449			/*
450			*---------------------------------------------------------------------------
451			*
452			* TclHandleRelease --
453			*
454			* This procedure is called to release an interest in the malloc'd
455			* block associated with the handle.
456			*
457			* Results:
458			* None.
459			*
460			* Side effects:
461			* The ref count of the handle is decremented. If the malloc'd block
462			* has been freed and if no one is using the handle any more, the
463			* handle will be reclaimed.
464			*
465			*---------------------------------------------------------------------------
466			*/
467
468			void
469			TclHandleRelease(handle)
470			TclHandle handle; /* Unregister interest in the block of
471			* memory referenced by this handle. */
472			{
473			HandleStruct *handlePtr;
474
475			handlePtr = (HandleStruct *) handle;
476			#ifdef TCL_MEM_DEBUG
477			if (handlePtr->refCount == 0x61616161) {
478			panic("using previously disposed TclHandle %x", handlePtr);
479			}
480			if ((handlePtr->ptr != NULL)
481			&& (handlePtr->ptr != handlePtr->ptr2)) {
482			panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
483			handlePtr, handlePtr->ptr2, handlePtr->ptr);
484			}
485			#endif
486			handlePtr->refCount--;
487			if ((handlePtr->refCount == 0) && (handlePtr->ptr == NULL)) {
488			ckfree((char *) handlePtr);
489			}
490			}
491
492			/* End of tclpreserve.c */