* private copies of some global data. This way we avoid most of the
 * synchronization calls which boosts performance, at cost of having to update
 * this information each time the corresponding epoch counter changes.
 */

typedef struct ThreadSpecificData {
    int initialized;
    size_t cwdPathEpoch;
    size_t filesystemEpoch;
    Tcl_Obj *cwdPathPtr;
    ClientData cwdClientData;
    FilesystemRecord *filesystemList;
    size_t claims;
} ThreadSpecificData;

/*
 * Prototypes for functions defined later in this file.
 */

static int		EvalFileCallback(ClientData data[],

/*
 * This is incremented each time we modify the linked list of filesystems. Any
 * time it changes, all cached filesystem representations are suspect and must
 * be freed. For multithreading builds, change of the filesystem epoch will
 * trigger cache cleanup in all threads.
 */

static size_t theFilesystemEpoch = 1;

/*
 * Stores the linked list of filesystems. A 1:1 copy of this list is also
 * maintained in the TSD for each thread. This is to avoid synchronization
 * issues.
 */

static FilesystemRecord *filesystemList = &nativeFilesystemRecord;
TCL_DECLARE_MUTEX(filesystemMutex)

/*
 * Used to implement Tcl_FSGetCwd in a file-system independent way.
 */

static Tcl_Obj *cwdPathPtr = NULL;
static size_t cwdPathEpoch = 0;
static ClientData cwdClientData = NULL;
TCL_DECLARE_MUTEX(cwdMutex)

static Tcl_ThreadDataKey fsDataKey;

/*
 * One of these structures is used each time we successfully load a file from

/*
 * The epoch can be changed both by filesystems being added or removed and by
 * env(HOME) changing.
 */

int
TclFSEpochOk(
    size_t filesystemEpoch)
{
    return (filesystemEpoch == 0 || filesystemEpoch == theFilesystemEpoch);
}

static void
Claim(void)
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&fsDataKey);

    tsdPtr->claims++;
}

static void
Disclaim(void)
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&fsDataKey);

    tsdPtr->claims--;
}

size_t
TclFSEpoch(void)
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&fsDataKey);

    return tsdPtr->filesystemEpoch;
}

	 */

	cwdPathPtr = Tcl_NewStringObj(str, len);
	Tcl_IncrRefCount(cwdPathPtr);
	cwdClientData = TclNativeDupInternalRep(clientData);
    }

    if (++cwdPathEpoch == 0) {
	++cwdPathEpoch;
    }
    tsdPtr->cwdPathEpoch = cwdPathEpoch;
    Tcl_MutexUnlock(&cwdMutex);

    if (tsdPtr->cwdPathPtr) {
	Tcl_DecrRefCount(tsdPtr->cwdPathPtr);
    }
    if (tsdPtr->cwdClientData) {

	if (fsRecPtr != &nativeFilesystemRecord) {
	    ckfree(fsRecPtr);
	}
	fsRecPtr = tmpFsRecPtr;
    }
    if (++theFilesystemEpoch == 0) {
	++theFilesystemEpoch;
    }
    filesystemList = NULL;

    /*
     * Now filesystemList is NULL. This means that any attempt to use the
     * filesystem is likely to fail.
     */

 */

void
TclResetFilesystem(void)
{
    filesystemList = &nativeFilesystemRecord;
    if (++theFilesystemEpoch == 0) {
	++theFilesystemEpoch;
    }

#ifdef _WIN32
    /*
     * Cleans up the win32 API filesystem proc lookup table. This must happen
     * very late in finalization so that deleting of copied dlls can occur.
     */

    /*
     * Increment the filesystem epoch counter, since existing paths might
     * conceivably now belong to different filesystems.
     */

    if (++theFilesystemEpoch == 0) {
	++theFilesystemEpoch;
    }
    Tcl_MutexUnlock(&filesystemMutex);

    return TCL_OK;
}

/*

	     * might conceivably now belong to different filesystems. This
	     * should also ensure that paths which have cached the filesystem
	     * which is about to be deleted do not reference that filesystem
	     * (which would of course lead to memory exceptions).
	     */

	    if (++theFilesystemEpoch == 0) {
		++theFilesystemEpoch;
	    }

	    ckfree(fsRecPtr);

	    retVal = TCL_OK;
	} else {
	    fsRecPtr = fsRecPtr->nextPtr;

    /*
     * Increment the filesystem epoch counter, since existing paths might now
     * belong to different filesystems.
     */

    Tcl_MutexLock(&filesystemMutex);
    if (++theFilesystemEpoch == 0) {
	++theFilesystemEpoch;
    }
    Tcl_MutexUnlock(&filesystemMutex);
}

/*
 *----------------------------------------------------------------------
 *