Merge commit '9966985d896629eede849a84f18e406d1164a16c' as 'tcl8.6'

1 files changed, 4825 insertions, 0 deletions

diff --git a/tcl8.6/generic/tclInterp.c b/tcl8.6/generic/tclInterp.c
new file mode 100644
index 0000000..66ce1e0
--- /dev/null
+++ b/tcl8.6/generic/tclInterp.c
@@ -0,0 +1,4825 @@
+/*
+ * tclInterp.c --
+ *
+ *	This file implements the "interp" command which allows creation and
+ *	manipulation of Tcl interpreters from within Tcl scripts.
+ *
+ * Copyright (c) 1995-1997 Sun Microsystems, Inc.
+ * Copyright (c) 2004 Donal K. Fellows
+ *
+ * See the file "license.terms" for information on usage and redistribution
+ * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ */
+
+#include "tclInt.h"
+
+/*
+ * A pointer to a string that holds an initialization script that if non-NULL
+ * is evaluated in Tcl_Init() prior to the built-in initialization script
+ * above. This variable can be modified by the function below.
+ */
+
+static const char *tclPreInitScript = NULL;
+
+/* Forward declaration */
+struct Target;
+
+/*
+ * struct Alias:
+ *
+ * Stores information about an alias. Is stored in the slave interpreter and
+ * used by the source command to find the target command in the master when
+ * the source command is invoked.
+ */
+
+typedef struct Alias {
+    Tcl_Obj *token;		/* Token for the alias command in the slave
+				 * interp. This used to be the command name in
+				 * the slave when the alias was first
+				 * created. */
+    Tcl_Interp *targetInterp;	/* Interp in which target command will be
+				 * invoked. */
+    Tcl_Command slaveCmd;	/* Source command in slave interpreter, bound
+				 * to command that invokes the target command
+				 * in the target interpreter. */
+    Tcl_HashEntry *aliasEntryPtr;
+				/* Entry for the alias hash table in slave.
+				 * This is used by alias deletion to remove
+				 * the alias from the slave interpreter alias
+				 * table. */
+    struct Target *targetPtr;	/* Entry for target command in master. This is
+				 * used in the master interpreter to map back
+				 * from the target command to aliases
+				 * redirecting to it. */
+    int objc;			/* Count of Tcl_Obj in the prefix of the
+				 * target command to be invoked in the target
+				 * interpreter. Additional arguments specified
+				 * when calling the alias in the slave interp
+				 * will be appended to the prefix before the
+				 * command is invoked. */
+    Tcl_Obj *objPtr;		/* The first actual prefix object - the target
+				 * command name; this has to be at the end of
+				 * the structure, which will be extended to
+				 * accomodate the remaining objects in the
+				 * prefix. */
+} Alias;
+
+/*
+ *
+ * struct Slave:
+ *
+ * Used by the "interp" command to record and find information about slave
+ * interpreters. Maps from a command name in the master to information about a
+ * slave interpreter, e.g. what aliases are defined in it.
+ */
+
+typedef struct Slave {
+    Tcl_Interp *masterInterp;	/* Master interpreter for this slave. */
+    Tcl_HashEntry *slaveEntryPtr;
+				/* Hash entry in masters slave table for this
+				 * slave interpreter. Used to find this
+				 * record, and used when deleting the slave
+				 * interpreter to delete it from the master's
+				 * table. */
+    Tcl_Interp	*slaveInterp;	/* The slave interpreter. */
+    Tcl_Command interpCmd;	/* Interpreter object command. */
+    Tcl_HashTable aliasTable;	/* Table which maps from names of commands in
+				 * slave interpreter to struct Alias defined
+				 * below. */
+} Slave;
+
+/*
+ * struct Target:
+ *
+ * Maps from master interpreter commands back to the source commands in slave
+ * interpreters. This is needed because aliases can be created between sibling
+ * interpreters and must be deleted when the target interpreter is deleted. In
+ * case they would not be deleted the source interpreter would be left with a
+ * "dangling pointer". One such record is stored in the Master record of the
+ * master interpreter with the master for each alias which directs to a
+ * command in the master. These records are used to remove the source command
+ * for an from a slave if/when the master is deleted. They are organized in a
+ * doubly-linked list attached to the master interpreter.
+ */
+
+typedef struct Target {
+    Tcl_Command	slaveCmd;	/* Command for alias in slave interp. */
+    Tcl_Interp *slaveInterp;	/* Slave Interpreter. */
+    struct Target *nextPtr;	/* Next in list of target records, or NULL if
+				 * at the end of the list of targets. */
+    struct Target *prevPtr;	/* Previous in list of target records, or NULL
+				 * if at the start of the list of targets. */
+} Target;
+
+/*
+ * struct Master:
+ *
+ * This record is used for two purposes: First, slaveTable (a hashtable) maps
+ * from names of commands to slave interpreters. This hashtable is used to
+ * store information about slave interpreters of this interpreter, to map over
+ * all slaves, etc. The second purpose is to store information about all
+ * aliases in slaves (or siblings) which direct to target commands in this
+ * interpreter (using the targetsPtr doubly-linked list).
+ *
+ * NB: the flags field in the interp structure, used with SAFE_INTERP mask
+ * denotes whether the interpreter is safe or not. Safe interpreters have
+ * restricted functionality, can only create safe slave interpreters and can
+ * only load safe extensions.
+ */
+
+typedef struct Master {
+    Tcl_HashTable slaveTable;	/* Hash table for slave interpreters. Maps
+				 * from command names to Slave records. */
+    Target *targetsPtr;		/* The head of a doubly-linked list of all the
+				 * target records which denote aliases from
+				 * slaves or sibling interpreters that direct
+				 * to commands in this interpreter. This list
+				 * is used to remove dangling pointers from
+				 * the slave (or sibling) interpreters when
+				 * this interpreter is deleted. */
+} Master;
+
+/*
+ * The following structure keeps track of all the Master and Slave information
+ * on a per-interp basis.
+ */
+
+typedef struct InterpInfo {
+    Master master;		/* Keeps track of all interps for which this
+				 * interp is the Master. */
+    Slave slave;		/* Information necessary for this interp to
+				 * function as a slave. */
+} InterpInfo;
+
+/*
+ * Limit callbacks handled by scripts are modelled as structures which are
+ * stored in hashes indexed by a two-word key. Note that the type of the
+ * 'type' field in the key is not int; this is to make sure that things are
+ * likely to work properly on 64-bit architectures.
+ */
+
+typedef struct ScriptLimitCallback {
+    Tcl_Interp *interp;		/* The interpreter in which to execute the
+				 * callback. */
+    Tcl_Obj *scriptObj;		/* The script to execute to perform the
+				 * user-defined part of the callback. */
+    int type;			/* What kind of callback is this. */
+    Tcl_HashEntry *entryPtr;	/* The entry in the hash table maintained by
+				 * the target interpreter that refers to this
+				 * callback record, or NULL if the entry has
+				 * already been deleted from that hash
+				 * table. */
+} ScriptLimitCallback;
+
+typedef struct ScriptLimitCallbackKey {
+    Tcl_Interp *interp;		/* The interpreter that the limit callback was
+				 * attached to. This is not the interpreter
+				 * that the callback runs in! */
+    long type;			/* The type of callback that this is. */
+} ScriptLimitCallbackKey;
+
+/*
+ * TIP#143 limit handler internal representation.
+ */
+
+struct LimitHandler {
+    int flags;			/* The state of this particular handler. */
+    Tcl_LimitHandlerProc *handlerProc;
+				/* The handler callback. */
+    ClientData clientData;	/* Opaque argument to the handler callback. */
+    Tcl_LimitHandlerDeleteProc *deleteProc;
+				/* How to delete the clientData. */
+    LimitHandler *prevPtr;	/* Previous item in linked list of
+				 * handlers. */
+    LimitHandler *nextPtr;	/* Next item in linked list of handlers. */
+};
+
+/*
+ * Values for the LimitHandler flags field.
+ *      LIMIT_HANDLER_ACTIVE - Whether the handler is currently being
+ *              processed; handlers are never to be entered reentrantly.
+ *      LIMIT_HANDLER_DELETED - Whether the handler has been deleted. This
+ *              should not normally be observed because when a handler is
+ *              deleted it is also spliced out of the list of handlers, but
+ *              even so we will be careful.
+ */
+
+#define LIMIT_HANDLER_ACTIVE    0x01
+#define LIMIT_HANDLER_DELETED   0x02
+
+
+
+/*
+ * Prototypes for local static functions:
+ */
+
+static int		AliasCreate(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp, Tcl_Interp *masterInterp,
+			    Tcl_Obj *namePtr, Tcl_Obj *targetPtr, int objc,
+			    Tcl_Obj *const objv[]);
+static int		AliasDelete(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp, Tcl_Obj *namePtr);
+static int		AliasDescribe(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp, Tcl_Obj *objPtr);
+static int		AliasList(Tcl_Interp *interp, Tcl_Interp *slaveInterp);
+static int		AliasObjCmd(ClientData dummy,
+			    Tcl_Interp *currentInterp, int objc,
+			    Tcl_Obj *const objv[]);
+static int		AliasNRCmd(ClientData dummy,
+			    Tcl_Interp *currentInterp, int objc,
+			    Tcl_Obj *const objv[]);
+static void		AliasObjCmdDeleteProc(ClientData clientData);
+static Tcl_Interp *	GetInterp(Tcl_Interp *interp, Tcl_Obj *pathPtr);
+static Tcl_Interp *	GetInterp2(Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const objv[]);
+static void		InterpInfoDeleteProc(ClientData clientData,
+			    Tcl_Interp *interp);
+static int		SlaveBgerror(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp, int objc,
+			    Tcl_Obj *const objv[]);
+static Tcl_Interp *	SlaveCreate(Tcl_Interp *interp, Tcl_Obj *pathPtr,
+			    int safe);
+static int		SlaveDebugCmd(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp,
+			    int objc, Tcl_Obj *const objv[]);
+static int		SlaveEval(Tcl_Interp *interp, Tcl_Interp *slaveInterp,
+			    int objc, Tcl_Obj *const objv[]);
+static int		SlaveExpose(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp, int objc,
+			    Tcl_Obj *const objv[]);
+static int		SlaveHide(Tcl_Interp *interp, Tcl_Interp *slaveInterp,
+			    int objc, Tcl_Obj *const objv[]);
+static int		SlaveHidden(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp);
+static int		SlaveInvokeHidden(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp,
+			    const char *namespaceName,
+			    int objc, Tcl_Obj *const objv[]);
+static int		SlaveMarkTrusted(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp);
+static int		SlaveObjCmd(ClientData dummy, Tcl_Interp *interp,
+			    int objc, Tcl_Obj *const objv[]);
+static void		SlaveObjCmdDeleteProc(ClientData clientData);
+static int		SlaveRecursionLimit(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp, int objc,
+			    Tcl_Obj *const objv[]);
+static int		SlaveCommandLimitCmd(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp, int consumedObjc,
+			    int objc, Tcl_Obj *const objv[]);
+static int		SlaveTimeLimitCmd(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp, int consumedObjc,
+			    int objc, Tcl_Obj *const objv[]);
+static void		InheritLimitsFromMaster(Tcl_Interp *slaveInterp,
+			    Tcl_Interp *masterInterp);
+static void		SetScriptLimitCallback(Tcl_Interp *interp, int type,
+			    Tcl_Interp *targetInterp, Tcl_Obj *scriptObj);
+static void		CallScriptLimitCallback(ClientData clientData,
+			    Tcl_Interp *interp);
+static void		DeleteScriptLimitCallback(ClientData clientData);
+static void		RunLimitHandlers(LimitHandler *handlerPtr,
+			    Tcl_Interp *interp);
+static void		TimeLimitCallback(ClientData clientData);
+
+/* NRE enabling */
+static Tcl_NRPostProc	NRPostInvokeHidden;
+static Tcl_ObjCmdProc	NRInterpCmd;
+static Tcl_ObjCmdProc	NRSlaveCmd;
+
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclSetPreInitScript --
+ *
+ *	This routine is used to change the value of the internal variable,
+ *	tclPreInitScript.
+ *
+ * Results:
+ *	Returns the current value of tclPreInitScript.
+ *
+ * Side effects:
+ *	Changes the way Tcl_Init() routine behaves.
+ *
+ *----------------------------------------------------------------------
+ */
+
+const char *
+TclSetPreInitScript(
+    const char *string)		/* Pointer to a script. */
+{
+    const char *prevString = tclPreInitScript;
+    tclPreInitScript = string;
+    return(prevString);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_Init --
+ *
+ *	This function is typically invoked by Tcl_AppInit functions to find
+ *	and source the "init.tcl" script, which should exist somewhere on the
+ *	Tcl library path.
+ *
+ * Results:
+ *	Returns a standard Tcl completion code and sets the interp's result if
+ *	there is an error.
+ *
+ * Side effects:
+ *	Depends on what's in the init.tcl script.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_Init(
+    Tcl_Interp *interp)		/* Interpreter to initialize. */
+{
+    if (tclPreInitScript != NULL) {
+	if (Tcl_Eval(interp, tclPreInitScript) == TCL_ERROR) {
+	    return TCL_ERROR;
+	}
+    }
+
+    /*
+     * In order to find init.tcl during initialization, the following script
+     * is invoked by Tcl_Init(). It looks in several different directories:
+     *
+     *	$tcl_library		- can specify a primary location, if set, no
+     *				  other locations will be checked. This is the
+     *				  recommended way for a program that embeds
+     *				  Tcl to specifically tell Tcl where to find
+     *				  an init.tcl file.
+     *
+     *	$env(TCL_LIBRARY)	- highest priority so user can always override
+     *				  the search path unless the application has
+     *				  specified an exact directory above
+     *
+     *	$tclDefaultLibrary	- INTERNAL: This variable is set by Tcl on
+     *				  those platforms where it can determine at
+     *				  runtime the directory where it expects the
+     *				  init.tcl file to be. After [tclInit] reads
+     *				  and uses this value, it [unset]s it.
+     *				  External users of Tcl should not make use of
+     *				  the variable to customize [tclInit].
+     *
+     *	$tcl_libPath		- OBSOLETE: This variable is no longer set by
+     *				  Tcl itself, but [tclInit] examines it in
+     *				  case some program that embeds Tcl is
+     *				  customizing [tclInit] by setting this
+     *				  variable to a list of directories in which
+     *				  to search.
+     *
+     *	[tcl::pkgconfig get scriptdir,runtime]
+     *				- the directory determined by configure to be
+     *				  the place where Tcl's script library is to
+     *				  be installed.
+     *
+     * The first directory on this path that contains a valid init.tcl script
+     * will be set as the value of tcl_library.
+     *
+     * Note that this entire search mechanism can be bypassed by defining an
+     * alternate tclInit command before calling Tcl_Init().
+     */
+
+    return Tcl_Eval(interp,
+"if {[namespace which -command tclInit] eq \"\"} {\n"
+"  proc tclInit {} {\n"
+"    global tcl_libPath tcl_library env tclDefaultLibrary\n"
+"    rename tclInit {}\n"
+"    if {[info exists tcl_library]} {\n"
+"	set scripts {{set tcl_library}}\n"
+"    } else {\n"
+"	set scripts {}\n"
+"	if {[info exists env(TCL_LIBRARY)] && ($env(TCL_LIBRARY) ne {})} {\n"
+"	    lappend scripts {set env(TCL_LIBRARY)}\n"
+"	    lappend scripts {\n"
+"if {[regexp ^tcl(.*)$ [file tail $env(TCL_LIBRARY)] -> tail] == 0} continue\n"
+"if {$tail eq [info tclversion]} continue\n"
+"file join [file dirname $env(TCL_LIBRARY)] tcl[info tclversion]}\n"
+"	}\n"
+"	if {[info exists tclDefaultLibrary]} {\n"
+"	    lappend scripts {set tclDefaultLibrary}\n"
+"	} else {\n"
+"	    lappend scripts {::tcl::pkgconfig get scriptdir,runtime}\n"
+"	}\n"
+"	lappend scripts {\n"
+"set parentDir [file dirname [file dirname [info nameofexecutable]]]\n"
+"set grandParentDir [file dirname $parentDir]\n"
+"file join $parentDir lib tcl[info tclversion]} \\\n"
+"	{file join $grandParentDir lib tcl[info tclversion]} \\\n"
+"	{file join $parentDir library} \\\n"
+"	{file join $grandParentDir library} \\\n"
+"	{file join $grandParentDir tcl[info patchlevel] library} \\\n"
+"	{\n"
+"file join [file dirname $grandParentDir] tcl[info patchlevel] library}\n"
+"	if {[info exists tcl_libPath]\n"
+"		&& [catch {llength $tcl_libPath} len] == 0} {\n"
+"	    for {set i 0} {$i < $len} {incr i} {\n"
+"		lappend scripts [list lindex \\$tcl_libPath $i]\n"
+"	    }\n"
+"	}\n"
+"    }\n"
+"    set dirs {}\n"
+"    set errors {}\n"
+"    foreach script $scripts {\n"
+"	lappend dirs [eval $script]\n"
+"	set tcl_library [lindex $dirs end]\n"
+"	set tclfile [file join $tcl_library init.tcl]\n"
+"	if {[file exists $tclfile]} {\n"
+"	    if {[catch {uplevel #0 [list source $tclfile]} msg opts]} {\n"
+"		append errors \"$tclfile: $msg\n\"\n"
+"		append errors \"[dict get $opts -errorinfo]\n\"\n"
+"		continue\n"
+"	    }\n"
+"	    unset -nocomplain tclDefaultLibrary\n"
+"	    return\n"
+"	}\n"
+"    }\n"
+"    unset -nocomplain tclDefaultLibrary\n"
+"    set msg \"Can't find a usable init.tcl in the following directories: \n\"\n"
+"    append msg \"    $dirs\n\n\"\n"
+"    append msg \"$errors\n\n\"\n"
+"    append msg \"This probably means that Tcl wasn't installed properly.\n\"\n"
+"    error $msg\n"
+"  }\n"
+"}\n"
+"tclInit");
+}
+
+/*
+ *---------------------------------------------------------------------------
+ *
+ * TclInterpInit --
+ *
+ *	Initializes the invoking interpreter for using the master, slave and
+ *	safe interp facilities. This is called from inside Tcl_CreateInterp().
+ *
+ * Results:
+ *	Always returns TCL_OK for backwards compatibility.
+ *
+ * Side effects:
+ *	Adds the "interp" command to an interpreter and initializes the
+ *	interpInfoPtr field of the invoking interpreter.
+ *
+ *---------------------------------------------------------------------------
+ */
+
+int
+TclInterpInit(
+    Tcl_Interp *interp)		/* Interpreter to initialize. */
+{
+    InterpInfo *interpInfoPtr;
+    Master *masterPtr;
+    Slave *slavePtr;
+
+    interpInfoPtr = ckalloc(sizeof(InterpInfo));
+    ((Interp *) interp)->interpInfo = interpInfoPtr;
+
+    masterPtr = &interpInfoPtr->master;
+    Tcl_InitHashTable(&masterPtr->slaveTable, TCL_STRING_KEYS);
+    masterPtr->targetsPtr = NULL;
+
+    slavePtr = &interpInfoPtr->slave;
+    slavePtr->masterInterp	= NULL;
+    slavePtr->slaveEntryPtr	= NULL;
+    slavePtr->slaveInterp	= interp;
+    slavePtr->interpCmd		= NULL;
+    Tcl_InitHashTable(&slavePtr->aliasTable, TCL_STRING_KEYS);
+
+    Tcl_NRCreateCommand(interp, "interp", Tcl_InterpObjCmd, NRInterpCmd,
+	    NULL, NULL);
+
+    Tcl_CallWhenDeleted(interp, InterpInfoDeleteProc, NULL);
+    return TCL_OK;
+}
+
+/*
+ *---------------------------------------------------------------------------
+ *
+ * InterpInfoDeleteProc --
+ *
+ *	Invoked when an interpreter is being deleted. It releases all storage
+ *	used by the master/slave/safe interpreter facilities.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Cleans up storage. Sets the interpInfoPtr field of the interp to NULL.
+ *
+ *---------------------------------------------------------------------------
+ */
+
+static void
+InterpInfoDeleteProc(
+    ClientData clientData,	/* Ignored. */
+    Tcl_Interp *interp)		/* Interp being deleted. All commands for
+				 * slave interps should already be deleted. */
+{
+    InterpInfo *interpInfoPtr;
+    Slave *slavePtr;
+    Master *masterPtr;
+    Target *targetPtr;
+
+    interpInfoPtr = (InterpInfo *) ((Interp *) interp)->interpInfo;
+
+    /*
+     * There shouldn't be any commands left.
+     */
+
+    masterPtr = &interpInfoPtr->master;
+    if (masterPtr->slaveTable.numEntries != 0) {
+	Tcl_Panic("InterpInfoDeleteProc: still exist commands");
+    }
+    Tcl_DeleteHashTable(&masterPtr->slaveTable);
+
+    /*
+     * Tell any interps that have aliases to this interp that they should
+     * delete those aliases. If the other interp was already dead, it would
+     * have removed the target record already.
+     */
+
+    for (targetPtr = masterPtr->targetsPtr; targetPtr != NULL; ) {
+	Target *tmpPtr = targetPtr->nextPtr;
+	Tcl_DeleteCommandFromToken(targetPtr->slaveInterp,
+		targetPtr->slaveCmd);
+	targetPtr = tmpPtr;
+    }
+
+    slavePtr = &interpInfoPtr->slave;
+    if (slavePtr->interpCmd != NULL) {
+	/*
+	 * Tcl_DeleteInterp() was called on this interpreter, rather "interp
+	 * delete" or the equivalent deletion of the command in the master.
+	 * First ensure that the cleanup callback doesn't try to delete the
+	 * interp again.
+	 */
+
+	slavePtr->slaveInterp = NULL;
+	Tcl_DeleteCommandFromToken(slavePtr->masterInterp,
+		slavePtr->interpCmd);
+    }
+
+    /*
+     * There shouldn't be any aliases left.
+     */
+
+    if (slavePtr->aliasTable.numEntries != 0) {
+	Tcl_Panic("InterpInfoDeleteProc: still exist aliases");
+    }
+    Tcl_DeleteHashTable(&slavePtr->aliasTable);
+
+    ckfree(interpInfoPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_InterpObjCmd --
+ *
+ *	This function is invoked to process the "interp" Tcl command. See the
+ *	user documentation for details on what it does.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	See the user documentation.
+ *
+ *----------------------------------------------------------------------
+ */
+	/* ARGSUSED */
+int
+Tcl_InterpObjCmd(
+    ClientData clientData,		/* Unused. */
+    Tcl_Interp *interp,			/* Current interpreter. */
+    int objc,				/* Number of arguments. */
+    Tcl_Obj *const objv[])		/* Argument objects. */
+{
+    return Tcl_NRCallObjProc(interp, NRInterpCmd, clientData, objc, objv);
+}
+
+static int
+NRInterpCmd(
+    ClientData clientData,		/* Unused. */
+    Tcl_Interp *interp,			/* Current interpreter. */
+    int objc,				/* Number of arguments. */
+    Tcl_Obj *const objv[])		/* Argument objects. */
+{
+    Tcl_Interp *slaveInterp;
+    int index;
+    static const char *const options[] = {
+	"alias",	"aliases",	"bgerror",	"cancel",
+	"create",	"debug",	"delete",
+	"eval",		"exists",	"expose",
+	"hide",		"hidden",	"issafe",
+	"invokehidden",	"limit",	"marktrusted",	"recursionlimit",
+	"slaves",	"share",	"target",	"transfer",
+	NULL
+    };
+    enum option {
+	OPT_ALIAS,	OPT_ALIASES,	OPT_BGERROR,	OPT_CANCEL,
+	OPT_CREATE,	OPT_DEBUG,	OPT_DELETE,
+	OPT_EVAL,	OPT_EXISTS,	OPT_EXPOSE,
+	OPT_HIDE,	OPT_HIDDEN,	OPT_ISSAFE,
+	OPT_INVOKEHID,	OPT_LIMIT,	OPT_MARKTRUSTED,OPT_RECLIMIT,
+	OPT_SLAVES,	OPT_SHARE,	OPT_TARGET,	OPT_TRANSFER
+    };
+
+    if (objc < 2) {
+	Tcl_WrongNumArgs(interp, 1, objv, "cmd ?arg ...?");
+	return TCL_ERROR;
+    }
+    if (Tcl_GetIndexFromObj(interp, objv[1], options, "option", 0,
+	    &index) != TCL_OK) {
+	return TCL_ERROR;
+    }
+    switch ((enum option) index) {
+    case OPT_ALIAS: {
+	Tcl_Interp *masterInterp;
+
+	if (objc < 4) {
+	aliasArgs:
+	    Tcl_WrongNumArgs(interp, 2, objv,
+		    "slavePath slaveCmd ?masterPath masterCmd? ?arg ...?");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	if (objc == 4) {
+	    return AliasDescribe(interp, slaveInterp, objv[3]);
+	}
+	if ((objc == 5) && (TclGetString(objv[4])[0] == '\0')) {
+	    return AliasDelete(interp, slaveInterp, objv[3]);
+	}
+	if (objc > 5) {
+	    masterInterp = GetInterp(interp, objv[4]);
+	    if (masterInterp == NULL) {
+		return TCL_ERROR;
+	    }
+	    if (TclGetString(objv[5])[0] == '\0') {
+		if (objc == 6) {
+		    return AliasDelete(interp, slaveInterp, objv[3]);
+		}
+	    } else {
+		return AliasCreate(interp, slaveInterp, masterInterp, objv[3],
+			objv[5], objc - 6, objv + 6);
+	    }
+	}
+	goto aliasArgs;
+    }
+    case OPT_ALIASES:
+	slaveInterp = GetInterp2(interp, objc, objv);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return AliasList(interp, slaveInterp);
+    case OPT_BGERROR:
+	if (objc != 3 && objc != 4) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "path ?cmdPrefix?");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveBgerror(interp, slaveInterp, objc - 3, objv + 3);
+    case OPT_CANCEL: {
+	int i, flags;
+	Tcl_Obj *resultObjPtr;
+	static const char *const cancelOptions[] = {
+	    "-unwind",	"--",	NULL
+	};
+	enum option {
+	    OPT_UNWIND,	OPT_LAST
+	};
+
+	flags = 0;
+
+	for (i = 2; i < objc; i++) {
+	    if (TclGetString(objv[i])[0] != '-') {
+		break;
+	    }
+	    if (Tcl_GetIndexFromObj(interp, objv[i], cancelOptions, "option",
+		    0, &index) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+
+	    switch ((enum option) index) {
+	    case OPT_UNWIND:
+		/*
+		 * The evaluation stack in the target interp is to be unwound.
+		 */
+
+		flags |= TCL_CANCEL_UNWIND;
+		break;
+	    case OPT_LAST:
+		i++;
+		goto endOfForLoop;
+	    }
+	}
+
+    endOfForLoop:
+	if (i < objc - 2) {
+	    Tcl_WrongNumArgs(interp, 2, objv,
+		    "?-unwind? ?--? ?path? ?result?");
+	    return TCL_ERROR;
+	}
+
+	/*
+	 * Did they specify a slave interp to cancel the script in progress
+	 * in?  If not, use the current interp.
+	 */
+
+	if (i < objc) {
+	    slaveInterp = GetInterp(interp, objv[i]);
+	    if (slaveInterp == NULL) {
+		return TCL_ERROR;
+	    }
+	    i++;
+	} else {
+	    slaveInterp = interp;
+	}
+
+	if (i < objc) {
+	    resultObjPtr = objv[i];
+
+	    /*
+	     * Tcl_CancelEval removes this reference.
+	     */
+
+	    Tcl_IncrRefCount(resultObjPtr);
+	    i++;
+	} else {
+	    resultObjPtr = NULL;
+	}
+
+	return Tcl_CancelEval(slaveInterp, resultObjPtr, 0, flags);
+    }
+    case OPT_CREATE: {
+	int i, last, safe;
+	Tcl_Obj *slavePtr;
+	char buf[16 + TCL_INTEGER_SPACE];
+	static const char *const createOptions[] = {
+	    "-safe",	"--", NULL
+	};
+	enum option {
+	    OPT_SAFE,	OPT_LAST
+	};
+
+	safe = Tcl_IsSafe(interp);
+
+	/*
+	 * Weird historical rules: "-safe" is accepted at the end, too.
+	 */
+
+	slavePtr = NULL;
+	last = 0;
+	for (i = 2; i < objc; i++) {
+	    if ((last == 0) && (Tcl_GetString(objv[i])[0] == '-')) {
+		if (Tcl_GetIndexFromObj(interp, objv[i], createOptions,
+			"option", 0, &index) != TCL_OK) {
+		    return TCL_ERROR;
+		}
+		if (index == OPT_SAFE) {
+		    safe = 1;
+		    continue;
+		}
+		i++;
+		last = 1;
+	    }
+	    if (slavePtr != NULL) {
+		Tcl_WrongNumArgs(interp, 2, objv, "?-safe? ?--? ?path?");
+		return TCL_ERROR;
+	    }
+	    if (i < objc) {
+		slavePtr = objv[i];
+	    }
+	}
+	buf[0] = '\0';
+	if (slavePtr == NULL) {
+	    /*
+	     * Create an anonymous interpreter -- we choose its name and the
+	     * name of the command. We check that the command name that we use
+	     * for the interpreter does not collide with an existing command
+	     * in the master interpreter.
+	     */
+
+	    for (i = 0; ; i++) {
+		Tcl_CmdInfo cmdInfo;
+
+		sprintf(buf, "interp%d", i);
+		if (Tcl_GetCommandInfo(interp, buf, &cmdInfo) == 0) {
+		    break;
+		}
+	    }
+	    slavePtr = Tcl_NewStringObj(buf, -1);
+	}
+	if (SlaveCreate(interp, slavePtr, safe) == NULL) {
+	    if (buf[0] != '\0') {
+		Tcl_DecrRefCount(slavePtr);
+	    }
+	    return TCL_ERROR;
+	}
+	Tcl_SetObjResult(interp, slavePtr);
+	return TCL_OK;
+    }
+    case OPT_DEBUG:		/* TIP #378 */
+	/*
+	 * Currently only -frame supported, otherwise ?-option ?value??
+	 */
+
+	if (objc < 3 || objc > 5) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "path ?-frame ?bool??");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveDebugCmd(interp, slaveInterp, objc - 3, objv + 3);
+    case OPT_DELETE: {
+	int i;
+	InterpInfo *iiPtr;
+
+	for (i = 2; i < objc; i++) {
+	    slaveInterp = GetInterp(interp, objv[i]);
+	    if (slaveInterp == NULL) {
+		return TCL_ERROR;
+	    } else if (slaveInterp == interp) {
+		Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			"cannot delete the current interpreter", -1));
+		Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+			"DELETESELF", NULL);
+		return TCL_ERROR;
+	    }
+	    iiPtr = (InterpInfo *) ((Interp *) slaveInterp)->interpInfo;
+	    Tcl_DeleteCommandFromToken(iiPtr->slave.masterInterp,
+		    iiPtr->slave.interpCmd);
+	}
+	return TCL_OK;
+    }
+    case OPT_EVAL:
+	if (objc < 4) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "path arg ?arg ...?");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveEval(interp, slaveInterp, objc - 3, objv + 3);
+    case OPT_EXISTS: {
+	int exists = 1;
+
+	slaveInterp = GetInterp2(interp, objc, objv);
+	if (slaveInterp == NULL) {
+	    if (objc > 3) {
+		return TCL_ERROR;
+	    }
+	    Tcl_ResetResult(interp);
+	    exists = 0;
+	}
+	Tcl_SetObjResult(interp, Tcl_NewBooleanObj(exists));
+	return TCL_OK;
+    }
+    case OPT_EXPOSE:
+	if ((objc < 4) || (objc > 5)) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "path hiddenCmdName ?cmdName?");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveExpose(interp, slaveInterp, objc - 3, objv + 3);
+    case OPT_HIDE:
+	if ((objc < 4) || (objc > 5)) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "path cmdName ?hiddenCmdName?");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveHide(interp, slaveInterp, objc - 3, objv + 3);
+    case OPT_HIDDEN:
+	slaveInterp = GetInterp2(interp, objc, objv);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveHidden(interp, slaveInterp);
+    case OPT_ISSAFE:
+	slaveInterp = GetInterp2(interp, objc, objv);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	Tcl_SetObjResult(interp, Tcl_NewBooleanObj(Tcl_IsSafe(slaveInterp)));
+	return TCL_OK;
+    case OPT_INVOKEHID: {
+	int i;
+	const char *namespaceName;
+	static const char *const hiddenOptions[] = {
+	    "-global",	"-namespace",	"--", NULL
+	};
+	enum hiddenOption {
+	    OPT_GLOBAL,	OPT_NAMESPACE,	OPT_LAST
+	};
+
+	namespaceName = NULL;
+	for (i = 3; i < objc; i++) {
+	    if (TclGetString(objv[i])[0] != '-') {
+		break;
+	    }
+	    if (Tcl_GetIndexFromObj(interp, objv[i], hiddenOptions, "option",
+		    0, &index) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    if (index == OPT_GLOBAL) {
+		namespaceName = "::";
+	    } else if (index == OPT_NAMESPACE) {
+		if (++i == objc) { /* There must be more arguments. */
+		    break;
+		} else {
+		    namespaceName = TclGetString(objv[i]);
+		}
+	    } else {
+		i++;
+		break;
+	    }
+	}
+	if (objc - i < 1) {
+	    Tcl_WrongNumArgs(interp, 2, objv,
+		    "path ?-namespace ns? ?-global? ?--? cmd ?arg ..?");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveInvokeHidden(interp, slaveInterp, namespaceName, objc - i,
+		objv + i);
+    }
+    case OPT_LIMIT: {
+	static const char *const limitTypes[] = {
+	    "commands", "time", NULL
+	};
+	enum LimitTypes {
+	    LIMIT_TYPE_COMMANDS, LIMIT_TYPE_TIME
+	};
+	int limitType;
+
+	if (objc < 4) {
+	    Tcl_WrongNumArgs(interp, 2, objv,
+		    "path limitType ?-option value ...?");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	if (Tcl_GetIndexFromObj(interp, objv[3], limitTypes, "limit type", 0,
+		&limitType) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	switch ((enum LimitTypes) limitType) {
+	case LIMIT_TYPE_COMMANDS:
+	    return SlaveCommandLimitCmd(interp, slaveInterp, 4, objc,objv);
+	case LIMIT_TYPE_TIME:
+	    return SlaveTimeLimitCmd(interp, slaveInterp, 4, objc, objv);
+	}
+    }
+    case OPT_MARKTRUSTED:
+	if (objc != 3) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "path");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveMarkTrusted(interp, slaveInterp);
+    case OPT_RECLIMIT:
+	if (objc != 3 && objc != 4) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "path ?newlimit?");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveRecursionLimit(interp, slaveInterp, objc - 3, objv + 3);
+    case OPT_SLAVES: {
+	InterpInfo *iiPtr;
+	Tcl_Obj *resultPtr;
+	Tcl_HashEntry *hPtr;
+	Tcl_HashSearch hashSearch;
+	char *string;
+
+	slaveInterp = GetInterp2(interp, objc, objv);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	iiPtr = (InterpInfo *) ((Interp *) slaveInterp)->interpInfo;
+	resultPtr = Tcl_NewObj();
+	hPtr = Tcl_FirstHashEntry(&iiPtr->master.slaveTable, &hashSearch);
+	for ( ; hPtr != NULL; hPtr = Tcl_NextHashEntry(&hashSearch)) {
+	    string = Tcl_GetHashKey(&iiPtr->master.slaveTable, hPtr);
+	    Tcl_ListObjAppendElement(NULL, resultPtr,
+		    Tcl_NewStringObj(string, -1));
+	}
+	Tcl_SetObjResult(interp, resultPtr);
+	return TCL_OK;
+    }
+    case OPT_TRANSFER:
+    case OPT_SHARE: {
+	Tcl_Interp *masterInterp;	/* The master of the slave. */
+	Tcl_Channel chan;
+
+	if (objc != 5) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "srcPath channelId destPath");
+	    return TCL_ERROR;
+	}
+	masterInterp = GetInterp(interp, objv[2]);
+	if (masterInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	chan = Tcl_GetChannel(masterInterp, TclGetString(objv[3]), NULL);
+	if (chan == NULL) {
+	    Tcl_TransferResult(masterInterp, TCL_OK, interp);
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[4]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	Tcl_RegisterChannel(slaveInterp, chan);
+	if (index == OPT_TRANSFER) {
+	    /*
+	     * When transferring, as opposed to sharing, we must unhitch the
+	     * channel from the interpreter where it started.
+	     */
+
+	    if (Tcl_UnregisterChannel(masterInterp, chan) != TCL_OK) {
+		Tcl_TransferResult(masterInterp, TCL_OK, interp);
+		return TCL_ERROR;
+	    }
+	}
+	return TCL_OK;
+    }
+    case OPT_TARGET: {
+	InterpInfo *iiPtr;
+	Tcl_HashEntry *hPtr;
+	Alias *aliasPtr;
+	const char *aliasName;
+
+	if (objc != 4) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "path alias");
+	    return TCL_ERROR;
+	}
+
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+
+	aliasName = TclGetString(objv[3]);
+
+	iiPtr = (InterpInfo *) ((Interp *) slaveInterp)->interpInfo;
+	hPtr = Tcl_FindHashEntry(&iiPtr->slave.aliasTable, aliasName);
+	if (hPtr == NULL) {
+	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		    "alias \"%s\" in path \"%s\" not found",
+		    aliasName, Tcl_GetString(objv[2])));
+	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ALIAS", aliasName,
+		    NULL);
+	    return TCL_ERROR;
+	}
+	aliasPtr = Tcl_GetHashValue(hPtr);
+	if (Tcl_GetInterpPath(interp, aliasPtr->targetInterp) != TCL_OK) {
+	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		    "target interpreter for alias \"%s\" in path \"%s\" is "
+		    "not my descendant", aliasName, Tcl_GetString(objv[2])));
+	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+		    "TARGETSHROUDED", NULL);
+	    return TCL_ERROR;
+	}
+	return TCL_OK;
+    }
+    }
+    return TCL_OK;
+}
+
+/*
+ *---------------------------------------------------------------------------
+ *
+ * GetInterp2 --
+ *
+ *	Helper function for Tcl_InterpObjCmd() to convert the interp name
+ *	potentially specified on the command line to an Tcl_Interp.
+ *
+ * Results:
+ *	The return value is the interp specified on the command line, or the
+ *	interp argument itself if no interp was specified on the command line.
+ *	If the interp could not be found or the wrong number of arguments was
+ *	specified on the command line, the return value is NULL and an error
+ *	message is left in the interp's result.
+ *
+ * Side effects:
+ *	None.
+ *
+ *---------------------------------------------------------------------------
+ */
+
+static Tcl_Interp *
+GetInterp2(
+    Tcl_Interp *interp,		/* Default interp if no interp was specified
+				 * on the command line. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    if (objc == 2) {
+	return interp;
+    } else if (objc == 3) {
+	return GetInterp(interp, objv[2]);
+    } else {
+	Tcl_WrongNumArgs(interp, 2, objv, "?path?");
+	return NULL;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_CreateAlias --
+ *
+ *	Creates an alias between two interpreters.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	Creates a new alias, manipulates the result field of slaveInterp.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_CreateAlias(
+    Tcl_Interp *slaveInterp,	/* Interpreter for source command. */
+    const char *slaveCmd,	/* Command to install in slave. */
+    Tcl_Interp *targetInterp,	/* Interpreter for target command. */
+    const char *targetCmd,	/* Name of target command. */
+    int argc,			/* How many additional arguments? */
+    const char *const *argv)	/* These are the additional args. */
+{
+    Tcl_Obj *slaveObjPtr, *targetObjPtr;
+    Tcl_Obj **objv;
+    int i;
+    int result;
+
+    objv = TclStackAlloc(slaveInterp, (unsigned) sizeof(Tcl_Obj *) * argc);
+    for (i = 0; i < argc; i++) {
+	objv[i] = Tcl_NewStringObj(argv[i], -1);
+	Tcl_IncrRefCount(objv[i]);
+    }
+
+    slaveObjPtr = Tcl_NewStringObj(slaveCmd, -1);
+    Tcl_IncrRefCount(slaveObjPtr);
+
+    targetObjPtr = Tcl_NewStringObj(targetCmd, -1);
+    Tcl_IncrRefCount(targetObjPtr);
+
+    result = AliasCreate(slaveInterp, slaveInterp, targetInterp, slaveObjPtr,
+	    targetObjPtr, argc, objv);
+
+    for (i = 0; i < argc; i++) {
+	Tcl_DecrRefCount(objv[i]);
+    }
+    TclStackFree(slaveInterp, objv);
+    Tcl_DecrRefCount(targetObjPtr);
+    Tcl_DecrRefCount(slaveObjPtr);
+
+    return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_CreateAliasObj --
+ *
+ *	Object version: Creates an alias between two interpreters.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	Creates a new alias.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_CreateAliasObj(
+    Tcl_Interp *slaveInterp,	/* Interpreter for source command. */
+    const char *slaveCmd,	/* Command to install in slave. */
+    Tcl_Interp *targetInterp,	/* Interpreter for target command. */
+    const char *targetCmd,	/* Name of target command. */
+    int objc,			/* How many additional arguments? */
+    Tcl_Obj *const objv[])	/* Argument vector. */
+{
+    Tcl_Obj *slaveObjPtr, *targetObjPtr;
+    int result;
+
+    slaveObjPtr = Tcl_NewStringObj(slaveCmd, -1);
+    Tcl_IncrRefCount(slaveObjPtr);
+
+    targetObjPtr = Tcl_NewStringObj(targetCmd, -1);
+    Tcl_IncrRefCount(targetObjPtr);
+
+    result = AliasCreate(slaveInterp, slaveInterp, targetInterp, slaveObjPtr,
+	    targetObjPtr, objc, objv);
+
+    Tcl_DecrRefCount(slaveObjPtr);
+    Tcl_DecrRefCount(targetObjPtr);
+    return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetAlias --
+ *
+ *	Gets information about an alias.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetAlias(
+    Tcl_Interp *interp,		/* Interp to start search from. */
+    const char *aliasName,	/* Name of alias to find. */
+    Tcl_Interp **targetInterpPtr,
+				/* (Return) target interpreter. */
+    const char **targetNamePtr,	/* (Return) name of target command. */
+    int *argcPtr,		/* (Return) count of addnl args. */
+    const char ***argvPtr)	/* (Return) additional arguments. */
+{
+    InterpInfo *iiPtr = (InterpInfo *) ((Interp *) interp)->interpInfo;
+    Tcl_HashEntry *hPtr;
+    Alias *aliasPtr;
+    int i, objc;
+    Tcl_Obj **objv;
+
+    hPtr = Tcl_FindHashEntry(&iiPtr->slave.aliasTable, aliasName);
+    if (hPtr == NULL) {
+	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		"alias \"%s\" not found", aliasName));
+	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ALIAS", aliasName, NULL);
+	return TCL_ERROR;
+    }
+    aliasPtr = Tcl_GetHashValue(hPtr);
+    objc = aliasPtr->objc;
+    objv = &aliasPtr->objPtr;
+
+    if (targetInterpPtr != NULL) {
+	*targetInterpPtr = aliasPtr->targetInterp;
+    }
+    if (targetNamePtr != NULL) {
+	*targetNamePtr = TclGetString(objv[0]);
+    }
+    if (argcPtr != NULL) {
+	*argcPtr = objc - 1;
+    }
+    if (argvPtr != NULL) {
+	*argvPtr = (const char **)
+		ckalloc(sizeof(const char *) * (objc - 1));
+	for (i = 1; i < objc; i++) {
+	    (*argvPtr)[i - 1] = TclGetString(objv[i]);
+	}
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetAliasObj --
+ *
+ *	Object version: Gets information about an alias.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetAliasObj(
+    Tcl_Interp *interp,		/* Interp to start search from. */
+    const char *aliasName,	/* Name of alias to find. */
+    Tcl_Interp **targetInterpPtr,
+				/* (Return) target interpreter. */
+    const char **targetNamePtr,	/* (Return) name of target command. */
+    int *objcPtr,		/* (Return) count of addnl args. */
+    Tcl_Obj ***objvPtr)		/* (Return) additional args. */
+{
+    InterpInfo *iiPtr = (InterpInfo *) ((Interp *) interp)->interpInfo;
+    Tcl_HashEntry *hPtr;
+    Alias *aliasPtr;
+    int objc;
+    Tcl_Obj **objv;
+
+    hPtr = Tcl_FindHashEntry(&iiPtr->slave.aliasTable, aliasName);
+    if (hPtr == NULL) {
+	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		"alias \"%s\" not found", aliasName));
+	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ALIAS", aliasName, NULL);
+	return TCL_ERROR;
+    }
+    aliasPtr = Tcl_GetHashValue(hPtr);
+    objc = aliasPtr->objc;
+    objv = &aliasPtr->objPtr;
+
+    if (targetInterpPtr != NULL) {
+	*targetInterpPtr = aliasPtr->targetInterp;
+    }
+    if (targetNamePtr != NULL) {
+	*targetNamePtr = TclGetString(objv[0]);
+    }
+    if (objcPtr != NULL) {
+	*objcPtr = objc - 1;
+    }
+    if (objvPtr != NULL) {
+	*objvPtr = objv + 1;
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclPreventAliasLoop --
+ *
+ *	When defining an alias or renaming a command, prevent an alias loop
+ *	from being formed.
+ *
+ * Results:
+ *	A standard Tcl object result.
+ *
+ * Side effects:
+ *	If TCL_ERROR is returned, the function also stores an error message in
+ *	the interpreter's result object.
+ *
+ * NOTE:
+ *	This function is public internal (instead of being static to this
+ *	file) because it is also used from TclRenameCommand.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclPreventAliasLoop(
+    Tcl_Interp *interp,		/* Interp in which to report errors. */
+    Tcl_Interp *cmdInterp,	/* Interp in which the command is being
+				 * defined. */
+    Tcl_Command cmd)		/* Tcl command we are attempting to define. */
+{
+    Command *cmdPtr = (Command *) cmd;
+    Alias *aliasPtr, *nextAliasPtr;
+    Tcl_Command aliasCmd;
+    Command *aliasCmdPtr;
+
+    /*
+     * If we are not creating or renaming an alias, then it is always OK to
+     * create or rename the command.
+     */
+
+    if (cmdPtr->objProc != AliasObjCmd) {
+	return TCL_OK;
+    }
+
+    /*
+     * OK, we are dealing with an alias, so traverse the chain of aliases. If
+     * we encounter the alias we are defining (or renaming to) any in the
+     * chain then we have a loop.
+     */
+
+    aliasPtr = cmdPtr->objClientData;
+    nextAliasPtr = aliasPtr;
+    while (1) {
+	Tcl_Obj *cmdNamePtr;
+
+	/*
+	 * If the target of the next alias in the chain is the same as the
+	 * source alias, we have a loop.
+	 */
+
+	if (Tcl_InterpDeleted(nextAliasPtr->targetInterp)) {
+	    /*
+	     * The slave interpreter can be deleted while creating the alias.
+	     * [Bug #641195]
+	     */
+
+	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		    "cannot define or rename alias \"%s\": interpreter deleted",
+		    Tcl_GetCommandName(cmdInterp, cmd)));
+	    return TCL_ERROR;
+	}
+	cmdNamePtr = nextAliasPtr->objPtr;
+	aliasCmd = Tcl_FindCommand(nextAliasPtr->targetInterp,
+		TclGetString(cmdNamePtr),
+		Tcl_GetGlobalNamespace(nextAliasPtr->targetInterp),
+		/*flags*/ 0);
+	if (aliasCmd == NULL) {
+	    return TCL_OK;
+	}
+	aliasCmdPtr = (Command *) aliasCmd;
+	if (aliasCmdPtr == cmdPtr) {
+	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		    "cannot define or rename alias \"%s\": would create a loop",
+		    Tcl_GetCommandName(cmdInterp, cmd)));
+	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+		    "ALIASLOOP", NULL);
+	    return TCL_ERROR;
+	}
+
+	/*
+	 * Otherwise, follow the chain one step further. See if the target
+	 * command is an alias - if so, follow the loop to its target command.
+	 * Otherwise we do not have a loop.
+	 */
+
+	if (aliasCmdPtr->objProc != AliasObjCmd) {
+	    return TCL_OK;
+	}
+	nextAliasPtr = aliasCmdPtr->objClientData;
+    }
+
+    /* NOTREACHED */
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AliasCreate --
+ *
+ *	Helper function to do the work to actually create an alias.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	An alias command is created and entered into the alias table for the
+ *	slave interpreter.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+AliasCreate(
+    Tcl_Interp *interp,		/* Interp for error reporting. */
+    Tcl_Interp *slaveInterp,	/* Interp where alias cmd will live or from
+				 * which alias will be deleted. */
+    Tcl_Interp *masterInterp,	/* Interp in which target command will be
+				 * invoked. */
+    Tcl_Obj *namePtr,		/* Name of alias cmd. */
+    Tcl_Obj *targetNamePtr,	/* Name of target cmd. */
+    int objc,			/* Additional arguments to store */
+    Tcl_Obj *const objv[])	/* with alias. */
+{
+    Alias *aliasPtr;
+    Tcl_HashEntry *hPtr;
+    Target *targetPtr;
+    Slave *slavePtr;
+    Master *masterPtr;
+    Tcl_Obj **prefv;
+    int isNew, i;
+
+    aliasPtr = ckalloc(sizeof(Alias) + objc * sizeof(Tcl_Obj *));
+    aliasPtr->token = namePtr;
+    Tcl_IncrRefCount(aliasPtr->token);
+    aliasPtr->targetInterp = masterInterp;
+
+    aliasPtr->objc = objc + 1;
+    prefv = &aliasPtr->objPtr;
+
+    *prefv = targetNamePtr;
+    Tcl_IncrRefCount(targetNamePtr);
+    for (i = 0; i < objc; i++) {
+	*(++prefv) = objv[i];
+	Tcl_IncrRefCount(objv[i]);
+    }
+
+    Tcl_Preserve(slaveInterp);
+    Tcl_Preserve(masterInterp);
+
+    if (slaveInterp == masterInterp) {
+	aliasPtr->slaveCmd = Tcl_NRCreateCommand(slaveInterp,
+		TclGetString(namePtr), AliasObjCmd, AliasNRCmd, aliasPtr,
+		AliasObjCmdDeleteProc);
+    } else {
+    aliasPtr->slaveCmd = Tcl_CreateObjCommand(slaveInterp,
+	    TclGetString(namePtr), AliasObjCmd, aliasPtr,
+	    AliasObjCmdDeleteProc);
+    }
+
+    if (TclPreventAliasLoop(interp, slaveInterp,
+	    aliasPtr->slaveCmd) != TCL_OK) {
+	/*
+	 * Found an alias loop! The last call to Tcl_CreateObjCommand made the
+	 * alias point to itself. Delete the command and its alias record. Be
+	 * careful to wipe out its client data first, so the command doesn't
+	 * try to delete itself.
+	 */
+
+	Command *cmdPtr;
+
+	Tcl_DecrRefCount(aliasPtr->token);
+	Tcl_DecrRefCount(targetNamePtr);
+	for (i = 0; i < objc; i++) {
+	    Tcl_DecrRefCount(objv[i]);
+	}
+
+	cmdPtr = (Command *) aliasPtr->slaveCmd;
+	cmdPtr->clientData = NULL;
+	cmdPtr->deleteProc = NULL;
+	cmdPtr->deleteData = NULL;
+	Tcl_DeleteCommandFromToken(slaveInterp, aliasPtr->slaveCmd);
+
+	ckfree(aliasPtr);
+
+	/*
+	 * The result was already set by TclPreventAliasLoop.
+	 */
+
+	Tcl_Release(slaveInterp);
+	Tcl_Release(masterInterp);
+	return TCL_ERROR;
+    }
+
+    /*
+     * Make an entry in the alias table. If it already exists, retry.
+     */
+
+    slavePtr = &((InterpInfo *) ((Interp *) slaveInterp)->interpInfo)->slave;
+    while (1) {
+	Tcl_Obj *newToken;
+	const char *string;
+
+	string = TclGetString(aliasPtr->token);
+	hPtr = Tcl_CreateHashEntry(&slavePtr->aliasTable, string, &isNew);
+	if (isNew != 0) {
+	    break;
+	}
+
+	/*
+	 * The alias name cannot be used as unique token, it is already taken.
+	 * We can produce a unique token by prepending "::" repeatedly. This
+	 * algorithm is a stop-gap to try to maintain the command name as
+	 * token for most use cases, fearful of possible backwards compat
+	 * problems. A better algorithm would produce unique tokens that need
+	 * not be related to the command name.
+	 *
+	 * ATTENTION: the tests in interp.test and possibly safe.test depend
+	 * on the precise definition of these tokens.
+	 */
+
+	TclNewLiteralStringObj(newToken, "::");
+	Tcl_AppendObjToObj(newToken, aliasPtr->token);
+	Tcl_DecrRefCount(aliasPtr->token);
+	aliasPtr->token = newToken;
+	Tcl_IncrRefCount(aliasPtr->token);
+    }
+
+    aliasPtr->aliasEntryPtr = hPtr;
+    Tcl_SetHashValue(hPtr, aliasPtr);
+
+    /*
+     * Create the new command. We must do it after deleting any old command,
+     * because the alias may be pointing at a renamed alias, as in:
+     *
+     * interp alias {} foo {} bar		# Create an alias "foo"
+     * rename foo zop				# Now rename the alias
+     * interp alias {} foo {} zop		# Now recreate "foo"...
+     */
+
+    targetPtr = ckalloc(sizeof(Target));
+    targetPtr->slaveCmd = aliasPtr->slaveCmd;
+    targetPtr->slaveInterp = slaveInterp;
+
+    masterPtr = &((InterpInfo*) ((Interp*) masterInterp)->interpInfo)->master;
+    targetPtr->nextPtr = masterPtr->targetsPtr;
+    targetPtr->prevPtr = NULL;
+    if (masterPtr->targetsPtr != NULL) {
+	masterPtr->targetsPtr->prevPtr = targetPtr;
+    }
+    masterPtr->targetsPtr = targetPtr;
+    aliasPtr->targetPtr = targetPtr;
+
+    Tcl_SetObjResult(interp, aliasPtr->token);
+
+    Tcl_Release(slaveInterp);
+    Tcl_Release(masterInterp);
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AliasDelete --
+ *
+ *	Deletes the given alias from the slave interpreter given.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	Deletes the alias from the slave interpreter.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+AliasDelete(
+    Tcl_Interp *interp,		/* Interpreter for result & errors. */
+    Tcl_Interp *slaveInterp,	/* Interpreter containing alias. */
+    Tcl_Obj *namePtr)		/* Name of alias to delete. */
+{
+    Slave *slavePtr;
+    Alias *aliasPtr;
+    Tcl_HashEntry *hPtr;
+
+    /*
+     * If the alias has been renamed in the slave, the master can still use
+     * the original name (with which it was created) to find the alias to
+     * delete it.
+     */
+
+    slavePtr = &((InterpInfo *) ((Interp *) slaveInterp)->interpInfo)->slave;
+    hPtr = Tcl_FindHashEntry(&slavePtr->aliasTable, TclGetString(namePtr));
+    if (hPtr == NULL) {
+	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		"alias \"%s\" not found", TclGetString(namePtr)));
+	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ALIAS",
+		TclGetString(namePtr), NULL);
+	return TCL_ERROR;
+    }
+    aliasPtr = Tcl_GetHashValue(hPtr);
+    Tcl_DeleteCommandFromToken(slaveInterp, aliasPtr->slaveCmd);
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AliasDescribe --
+ *
+ *	Sets the interpreter's result object to a Tcl list describing the
+ *	given alias in the given interpreter: its target command and the
+ *	additional arguments to prepend to any invocation of the alias.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+AliasDescribe(
+    Tcl_Interp *interp,		/* Interpreter for result & errors. */
+    Tcl_Interp *slaveInterp,	/* Interpreter containing alias. */
+    Tcl_Obj *namePtr)		/* Name of alias to describe. */
+{
+    Slave *slavePtr;
+    Tcl_HashEntry *hPtr;
+    Alias *aliasPtr;
+    Tcl_Obj *prefixPtr;
+
+    /*
+     * If the alias has been renamed in the slave, the master can still use
+     * the original name (with which it was created) to find the alias to
+     * describe it.
+     */
+
+    slavePtr = &((InterpInfo *) ((Interp *) slaveInterp)->interpInfo)->slave;
+    hPtr = Tcl_FindHashEntry(&slavePtr->aliasTable, Tcl_GetString(namePtr));
+    if (hPtr == NULL) {
+	return TCL_OK;
+    }
+    aliasPtr = Tcl_GetHashValue(hPtr);
+    prefixPtr = Tcl_NewListObj(aliasPtr->objc, &aliasPtr->objPtr);
+    Tcl_SetObjResult(interp, prefixPtr);
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AliasList --
+ *
+ *	Computes a list of aliases defined in a slave interpreter.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+AliasList(
+    Tcl_Interp *interp,		/* Interp for data return. */
+    Tcl_Interp *slaveInterp)	/* Interp whose aliases to compute. */
+{
+    Tcl_HashEntry *entryPtr;
+    Tcl_HashSearch hashSearch;
+    Tcl_Obj *resultPtr = Tcl_NewObj();
+    Alias *aliasPtr;
+    Slave *slavePtr;
+
+    slavePtr = &((InterpInfo *) ((Interp *) slaveInterp)->interpInfo)->slave;
+
+    entryPtr = Tcl_FirstHashEntry(&slavePtr->aliasTable, &hashSearch);
+    for ( ; entryPtr != NULL; entryPtr = Tcl_NextHashEntry(&hashSearch)) {
+	aliasPtr = Tcl_GetHashValue(entryPtr);
+	Tcl_ListObjAppendElement(NULL, resultPtr, aliasPtr->token);
+    }
+    Tcl_SetObjResult(interp, resultPtr);
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AliasObjCmd --
+ *
+ *	This is the function that services invocations of aliases in a slave
+ *	interpreter. One such command exists for each alias. When invoked,
+ *	this function redirects the invocation to the target command in the
+ *	master interpreter as designated by the Alias record associated with
+ *	this command.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	Causes forwarding of the invocation; all possible side effects may
+ *	occur as a result of invoking the command to which the invocation is
+ *	forwarded.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+AliasNRCmd(
+    ClientData clientData,	/* Alias record. */
+    Tcl_Interp *interp,		/* Current interpreter. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument vector. */
+{
+    Alias *aliasPtr = clientData;
+    int prefc, cmdc, i;
+    Tcl_Obj **prefv, **cmdv;
+    Tcl_Obj *listPtr;
+    List *listRep;
+    int flags = TCL_EVAL_INVOKE;
+
+    /*
+     * Append the arguments to the command prefix and invoke the command in
+     * the target interp's global namespace.
+     */
+
+    prefc = aliasPtr->objc;
+    prefv = &aliasPtr->objPtr;
+    cmdc = prefc + objc - 1;
+
+    listPtr = Tcl_NewListObj(cmdc, NULL);
+    listRep = listPtr->internalRep.twoPtrValue.ptr1;
+    listRep->elemCount = cmdc;
+    cmdv = &listRep->elements;
+
+    prefv = &aliasPtr->objPtr;
+    memcpy(cmdv, prefv, (size_t) (prefc * sizeof(Tcl_Obj *)));
+    memcpy(cmdv+prefc, objv+1, (size_t) ((objc-1) * sizeof(Tcl_Obj *)));
+
+    for (i=0; i<cmdc; i++) {
+	Tcl_IncrRefCount(cmdv[i]);
+    }
+
+    /*
+     * Use the ensemble rewriting machinery to ensure correct error messages:
+     * only the source command should show, not the full target prefix.
+     */
+
+    if (TclInitRewriteEnsemble(interp, 1, prefc, objv)) {
+	TclNRAddCallback(interp, TclClearRootEnsemble, NULL, NULL, NULL, NULL);
+    }
+    TclSkipTailcall(interp);
+    return Tcl_NREvalObj(interp, listPtr, flags);
+}
+
+static int
+AliasObjCmd(
+    ClientData clientData,	/* Alias record. */
+    Tcl_Interp *interp,		/* Current interpreter. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument vector. */
+{
+#define ALIAS_CMDV_PREALLOC 10
+    Alias *aliasPtr = clientData;
+    Tcl_Interp *targetInterp = aliasPtr->targetInterp;
+    int result, prefc, cmdc, i;
+    Tcl_Obj **prefv, **cmdv;
+    Tcl_Obj *cmdArr[ALIAS_CMDV_PREALLOC];
+    Interp *tPtr = (Interp *) targetInterp;
+    int isRootEnsemble;
+
+    /*
+     * Append the arguments to the command prefix and invoke the command in
+     * the target interp's global namespace.
+     */
+
+    prefc = aliasPtr->objc;
+    prefv = &aliasPtr->objPtr;
+    cmdc = prefc + objc - 1;
+    if (cmdc <= ALIAS_CMDV_PREALLOC) {
+	cmdv = cmdArr;
+    } else {
+	cmdv = TclStackAlloc(interp, cmdc * sizeof(Tcl_Obj *));
+    }
+
+    memcpy(cmdv, prefv, (size_t) (prefc * sizeof(Tcl_Obj *)));
+    memcpy(cmdv+prefc, objv+1, (size_t) ((objc-1) * sizeof(Tcl_Obj *)));
+
+    Tcl_ResetResult(targetInterp);
+
+    for (i=0; i<cmdc; i++) {
+	Tcl_IncrRefCount(cmdv[i]);
+    }
+
+    /*
+     * Use the ensemble rewriting machinery to ensure correct error messages:
+     * only the source command should show, not the full target prefix.
+     */
+
+    isRootEnsemble = TclInitRewriteEnsemble((Tcl_Interp *)tPtr, 1, prefc, objv);
+
+    /*
+     * Protect the target interpreter if it isn't the same as the source
+     * interpreter so that we can continue to work with it after the target
+     * command completes.
+     */
+
+    if (targetInterp != interp) {
+	Tcl_Preserve(targetInterp);
+    }
+
+    /*
+     * Execute the target command in the target interpreter.
+     */
+
+    result = Tcl_EvalObjv(targetInterp, cmdc, cmdv, TCL_EVAL_INVOKE);
+
+    /*
+     * Clean up the ensemble rewrite info if we set it in the first place.
+     */
+
+    if (isRootEnsemble) {
+	TclResetRewriteEnsemble((Tcl_Interp *)tPtr, 1);
+    }
+
+    /*
+     * If it was a cross-interpreter alias, we need to transfer the result
+     * back to the source interpreter and release the lock we previously set
+     * on the target interpreter.
+     */
+
+    if (targetInterp != interp) {
+	Tcl_TransferResult(targetInterp, result, interp);
+	Tcl_Release(targetInterp);
+    }
+
+    for (i=0; i<cmdc; i++) {
+	Tcl_DecrRefCount(cmdv[i]);
+    }
+    if (cmdv != cmdArr) {
+	TclStackFree(interp, cmdv);
+    }
+    return result;
+#undef ALIAS_CMDV_PREALLOC
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AliasObjCmdDeleteProc --
+ *
+ *	Is invoked when an alias command is deleted in a slave. Cleans up all
+ *	storage associated with this alias.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Deletes the alias record and its entry in the alias table for the
+ *	interpreter.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+AliasObjCmdDeleteProc(
+    ClientData clientData)	/* The alias record for this alias. */
+{
+    Alias *aliasPtr = clientData;
+    Target *targetPtr;
+    int i;
+    Tcl_Obj **objv;
+
+    Tcl_DecrRefCount(aliasPtr->token);
+    objv = &aliasPtr->objPtr;
+    for (i = 0; i < aliasPtr->objc; i++) {
+	Tcl_DecrRefCount(objv[i]);
+    }
+    Tcl_DeleteHashEntry(aliasPtr->aliasEntryPtr);
+
+    /*
+     * Splice the target record out of the target interpreter's master list.
+     */
+
+    targetPtr = aliasPtr->targetPtr;
+    if (targetPtr->prevPtr != NULL) {
+	targetPtr->prevPtr->nextPtr = targetPtr->nextPtr;
+    } else {
+	Master *masterPtr = &((InterpInfo *) ((Interp *)
+		aliasPtr->targetInterp)->interpInfo)->master;
+
+	masterPtr->targetsPtr = targetPtr->nextPtr;
+    }
+    if (targetPtr->nextPtr != NULL) {
+	targetPtr->nextPtr->prevPtr = targetPtr->prevPtr;
+    }
+
+    ckfree(targetPtr);
+    ckfree(aliasPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_CreateSlave --
+ *
+ *	Creates a slave interpreter. The slavePath argument denotes the name
+ *	of the new slave relative to the current interpreter; the slave is a
+ *	direct descendant of the one-before-last component of the path,
+ *	e.g. it is a descendant of the current interpreter if the slavePath
+ *	argument contains only one component. Optionally makes the slave
+ *	interpreter safe.
+ *
+ * Results:
+ *	Returns the interpreter structure created, or NULL if an error
+ *	occurred.
+ *
+ * Side effects:
+ *	Creates a new interpreter and a new interpreter object command in the
+ *	interpreter indicated by the slavePath argument.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Interp *
+Tcl_CreateSlave(
+    Tcl_Interp *interp,		/* Interpreter to start search at. */
+    const char *slavePath,	/* Name of slave to create. */
+    int isSafe)			/* Should new slave be "safe" ? */
+{
+    Tcl_Obj *pathPtr;
+    Tcl_Interp *slaveInterp;
+
+    pathPtr = Tcl_NewStringObj(slavePath, -1);
+    slaveInterp = SlaveCreate(interp, pathPtr, isSafe);
+    Tcl_DecrRefCount(pathPtr);
+
+    return slaveInterp;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetSlave --
+ *
+ *	Finds a slave interpreter by its path name.
+ *
+ * Results:
+ *	Returns a Tcl_Interp * for the named interpreter or NULL if not found.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Interp *
+Tcl_GetSlave(
+    Tcl_Interp *interp,		/* Interpreter to start search from. */
+    const char *slavePath)	/* Path of slave to find. */
+{
+    Tcl_Obj *pathPtr;
+    Tcl_Interp *slaveInterp;
+
+    pathPtr = Tcl_NewStringObj(slavePath, -1);
+    slaveInterp = GetInterp(interp, pathPtr);
+    Tcl_DecrRefCount(pathPtr);
+
+    return slaveInterp;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetMaster --
+ *
+ *	Finds the master interpreter of a slave interpreter.
+ *
+ * Results:
+ *	Returns a Tcl_Interp * for the master interpreter or NULL if none.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Interp *
+Tcl_GetMaster(
+    Tcl_Interp *interp)		/* Get the master of this interpreter. */
+{
+    Slave *slavePtr;		/* Slave record of this interpreter. */
+
+    if (interp == NULL) {
+	return NULL;
+    }
+    slavePtr = &((InterpInfo *) ((Interp *) interp)->interpInfo)->slave;
+    return slavePtr->masterInterp;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclSetSlaveCancelFlags --
+ *
+ *	This function marks all slave interpreters belonging to a given
+ *	interpreter as being canceled or not canceled, depending on the
+ *	provided flags.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclSetSlaveCancelFlags(
+    Tcl_Interp *interp,		/* Set cancel flags of this interpreter. */
+    int flags,			/* Collection of OR-ed bits that control
+				 * the cancellation of the script. Only
+				 * TCL_CANCEL_UNWIND is currently
+				 * supported. */
+    int force)			/* Non-zero to ignore numLevels for the purpose
+				 * of resetting the cancellation flags. */
+{
+    Master *masterPtr;		/* Master record of given interpreter. */
+    Tcl_HashEntry *hPtr;	/* Search element. */
+    Tcl_HashSearch hashSearch;	/* Search variable. */
+    Slave *slavePtr;		/* Slave record of interpreter. */
+    Interp *iPtr;
+
+    if (interp == NULL) {
+	return;
+    }
+
+    flags &= (CANCELED | TCL_CANCEL_UNWIND);
+
+    masterPtr = &((InterpInfo *) ((Interp *) interp)->interpInfo)->master;
+
+    hPtr = Tcl_FirstHashEntry(&masterPtr->slaveTable, &hashSearch);
+    for ( ; hPtr != NULL; hPtr = Tcl_NextHashEntry(&hashSearch)) {
+	slavePtr = Tcl_GetHashValue(hPtr);
+	iPtr = (Interp *) slavePtr->slaveInterp;
+
+	if (iPtr == NULL) {
+	    continue;
+	}
+
+	if (flags == 0) {
+	    TclResetCancellation((Tcl_Interp *) iPtr, force);
+	} else {
+	    TclSetCancelFlags(iPtr, flags);
+	}
+
+	/*
+	 * Now, recursively handle this for the slaves of this slave
+	 * interpreter.
+	 */
+
+	TclSetSlaveCancelFlags((Tcl_Interp *) iPtr, flags, force);
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetInterpPath --
+ *
+ *	Sets the result of the asking interpreter to a proper Tcl list
+ *	containing the names of interpreters between the asking and target
+ *	interpreters. The target interpreter must be either the same as the
+ *	asking interpreter or one of its slaves (including recursively).
+ *
+ * Results:
+ *	TCL_OK if the target interpreter is the same as, or a descendant of,
+ *	the asking interpreter; TCL_ERROR else. This way one can distinguish
+ *	between the case where the asking and target interps are the same (an
+ *	empty list is the result, and TCL_OK is returned) and when the target
+ *	is not a descendant of the asking interpreter (in which case the Tcl
+ *	result is an error message and the function returns TCL_ERROR).
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetInterpPath(
+    Tcl_Interp *askingInterp,	/* Interpreter to start search from. */
+    Tcl_Interp *targetInterp)	/* Interpreter to find. */
+{
+    InterpInfo *iiPtr;
+
+    if (targetInterp == askingInterp) {
+	Tcl_SetObjResult(askingInterp, Tcl_NewObj());
+	return TCL_OK;
+    }
+    if (targetInterp == NULL) {
+	return TCL_ERROR;
+    }
+    iiPtr = (InterpInfo *) ((Interp *) targetInterp)->interpInfo;
+    if (Tcl_GetInterpPath(askingInterp, iiPtr->slave.masterInterp) != TCL_OK){
+	return TCL_ERROR;
+    }
+    Tcl_ListObjAppendElement(NULL, Tcl_GetObjResult(askingInterp),
+	    Tcl_NewStringObj(Tcl_GetHashKey(&iiPtr->master.slaveTable,
+		    iiPtr->slave.slaveEntryPtr), -1));
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetInterp --
+ *
+ *	Helper function to find a slave interpreter given a pathname.
+ *
+ * Results:
+ *	Returns the slave interpreter known by that name in the calling
+ *	interpreter, or NULL if no interpreter known by that name exists.
+ *
+ * Side effects:
+ *	Assigns to the pointer variable passed in, if not NULL.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static Tcl_Interp *
+GetInterp(
+    Tcl_Interp *interp,		/* Interp. to start search from. */
+    Tcl_Obj *pathPtr)		/* List object containing name of interp. to
+				 * be found. */
+{
+    Tcl_HashEntry *hPtr;	/* Search element. */
+    Slave *slavePtr;		/* Interim slave record. */
+    Tcl_Obj **objv;
+    int objc, i;
+    Tcl_Interp *searchInterp;	/* Interim storage for interp. to find. */
+    InterpInfo *masterInfoPtr;
+
+    if (TclListObjGetElements(interp, pathPtr, &objc, &objv) != TCL_OK) {
+	return NULL;
+    }
+
+    searchInterp = interp;
+    for (i = 0; i < objc; i++) {
+	masterInfoPtr = (InterpInfo *) ((Interp *) searchInterp)->interpInfo;
+	hPtr = Tcl_FindHashEntry(&masterInfoPtr->master.slaveTable,
+		TclGetString(objv[i]));
+	if (hPtr == NULL) {
+	    searchInterp = NULL;
+	    break;
+	}
+	slavePtr = Tcl_GetHashValue(hPtr);
+	searchInterp = slavePtr->slaveInterp;
+	if (searchInterp == NULL) {
+	    break;
+	}
+    }
+    if (searchInterp == NULL) {
+	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		"could not find interpreter \"%s\"", TclGetString(pathPtr)));
+	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "INTERP",
+		TclGetString(pathPtr), NULL);
+    }
+    return searchInterp;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveBgerror --
+ *
+ *	Helper function to set/query the background error handling command
+ *	prefix of an interp
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	When (objc == 1), slaveInterp will be set to a new background handler
+ *	of objv[0].
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveBgerror(
+    Tcl_Interp *interp,		/* Interp for error return. */
+    Tcl_Interp *slaveInterp,	/* Interp in which limit is set/queried. */
+    int objc,			/* Set or Query. */
+    Tcl_Obj *const objv[])	/* Argument strings. */
+{
+    if (objc) {
+	int length;
+
+	if (TCL_ERROR == TclListObjLength(NULL, objv[0], &length)
+		|| (length < 1)) {
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		    "cmdPrefix must be list of length >= 1", -1));
+	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+		    "BGERRORFORMAT", NULL);
+	    return TCL_ERROR;
+	}
+	TclSetBgErrorHandler(slaveInterp, objv[0]);
+    }
+    Tcl_SetObjResult(interp, TclGetBgErrorHandler(slaveInterp));
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveCreate --
+ *
+ *	Helper function to do the actual work of creating a slave interp and
+ *	new object command. Also optionally makes the new slave interpreter
+ *	"safe".
+ *
+ * Results:
+ *	Returns the new Tcl_Interp * if successful or NULL if not. If failed,
+ *	the result of the invoking interpreter contains an error message.
+ *
+ * Side effects:
+ *	Creates a new slave interpreter and a new object command.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static Tcl_Interp *
+SlaveCreate(
+    Tcl_Interp *interp,		/* Interp. to start search from. */
+    Tcl_Obj *pathPtr,		/* Path (name) of slave to create. */
+    int safe)			/* Should we make it "safe"? */
+{
+    Tcl_Interp *masterInterp, *slaveInterp;
+    Slave *slavePtr;
+    InterpInfo *masterInfoPtr;
+    Tcl_HashEntry *hPtr;
+    const char *path;
+    int isNew, objc;
+    Tcl_Obj **objv;
+
+    if (Tcl_ListObjGetElements(interp, pathPtr, &objc, &objv) != TCL_OK) {
+	return NULL;
+    }
+    if (objc < 2) {
+	masterInterp = interp;
+	path = TclGetString(pathPtr);
+    } else {
+	Tcl_Obj *objPtr;
+
+	objPtr = Tcl_NewListObj(objc - 1, objv);
+	masterInterp = GetInterp(interp, objPtr);
+	Tcl_DecrRefCount(objPtr);
+	if (masterInterp == NULL) {
+	    return NULL;
+	}
+	path = TclGetString(objv[objc - 1]);
+    }
+    if (safe == 0) {
+	safe = Tcl_IsSafe(masterInterp);
+    }
+
+    masterInfoPtr = (InterpInfo *) ((Interp *) masterInterp)->interpInfo;
+    hPtr = Tcl_CreateHashEntry(&masterInfoPtr->master.slaveTable, path,
+	    &isNew);
+    if (isNew == 0) {
+	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
+		"interpreter named \"%s\" already exists, cannot create",
+		path));
+	return NULL;
+    }
+
+    slaveInterp = Tcl_CreateInterp();
+    slavePtr = &((InterpInfo *) ((Interp *) slaveInterp)->interpInfo)->slave;
+    slavePtr->masterInterp = masterInterp;
+    slavePtr->slaveEntryPtr = hPtr;
+    slavePtr->slaveInterp = slaveInterp;
+    slavePtr->interpCmd = Tcl_NRCreateCommand(masterInterp, path,
+	    SlaveObjCmd, NRSlaveCmd, slaveInterp, SlaveObjCmdDeleteProc);
+    Tcl_InitHashTable(&slavePtr->aliasTable, TCL_STRING_KEYS);
+    Tcl_SetHashValue(hPtr, slavePtr);
+    Tcl_SetVar(slaveInterp, "tcl_interactive", "0", TCL_GLOBAL_ONLY);
+
+    /*
+     * Inherit the recursion limit.
+     */
+
+    ((Interp *) slaveInterp)->maxNestingDepth =
+	    ((Interp *) masterInterp)->maxNestingDepth;
+
+    if (safe) {
+	if (Tcl_MakeSafe(slaveInterp) == TCL_ERROR) {
+	    goto error;
+	}
+    } else {
+	if (Tcl_Init(slaveInterp) == TCL_ERROR) {
+	    goto error;
+	}
+
+	/*
+	 * This will create the "memory" command in slave interpreters if we
+	 * compiled with TCL_MEM_DEBUG, otherwise it does nothing.
+	 */
+
+	Tcl_InitMemory(slaveInterp);
+    }
+
+    /*
+     * Inherit the TIP#143 limits.
+     */
+
+    InheritLimitsFromMaster(slaveInterp, masterInterp);
+
+    /*
+     * The [clock] command presents a safe API, but uses unsafe features in
+     * its implementation. This means it has to be implemented in safe interps
+     * as an alias to a version in the (trusted) master.
+     */
+
+    if (safe) {
+	Tcl_Obj *clockObj;
+	int status;
+
+	TclNewLiteralStringObj(clockObj, "clock");
+	Tcl_IncrRefCount(clockObj);
+	status = AliasCreate(interp, slaveInterp, masterInterp, clockObj,
+		clockObj, 0, NULL);
+	Tcl_DecrRefCount(clockObj);
+	if (status != TCL_OK) {
+	    goto error2;
+	}
+    }
+
+    return slaveInterp;
+
+  error:
+    Tcl_TransferResult(slaveInterp, TCL_ERROR, interp);
+  error2:
+    Tcl_DeleteInterp(slaveInterp);
+
+    return NULL;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveObjCmd --
+ *
+ *	Command to manipulate an interpreter, e.g. to send commands to it to
+ *	be evaluated. One such command exists for each slave interpreter.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	See user documentation for details.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveObjCmd(
+    ClientData clientData,	/* Slave interpreter. */
+    Tcl_Interp *interp,		/* Current interpreter. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    return Tcl_NRCallObjProc(interp, NRSlaveCmd, clientData, objc, objv);
+}
+
+static int
+NRSlaveCmd(
+    ClientData clientData,	/* Slave interpreter. */
+    Tcl_Interp *interp,		/* Current interpreter. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    Tcl_Interp *slaveInterp = clientData;
+    int index;
+    static const char *const options[] = {
+	"alias",	"aliases",	"bgerror",	"debug",
+	"eval",		"expose",	"hide",		"hidden",
+	"issafe",	"invokehidden",	"limit",	"marktrusted",
+	"recursionlimit", NULL
+    };
+    enum options {
+	OPT_ALIAS,	OPT_ALIASES,	OPT_BGERROR,	OPT_DEBUG,
+	OPT_EVAL,	OPT_EXPOSE,	OPT_HIDE,	OPT_HIDDEN,
+	OPT_ISSAFE,	OPT_INVOKEHIDDEN, OPT_LIMIT,	OPT_MARKTRUSTED,
+	OPT_RECLIMIT
+    };
+
+    if (slaveInterp == NULL) {
+	Tcl_Panic("SlaveObjCmd: interpreter has been deleted");
+    }
+
+    if (objc < 2) {
+	Tcl_WrongNumArgs(interp, 1, objv, "cmd ?arg ...?");
+	return TCL_ERROR;
+    }
+    if (Tcl_GetIndexFromObj(interp, objv[1], options, "option", 0,
+	    &index) != TCL_OK) {
+	return TCL_ERROR;
+    }
+
+    switch ((enum options) index) {
+    case OPT_ALIAS:
+	if (objc > 2) {
+	    if (objc == 3) {
+		return AliasDescribe(interp, slaveInterp, objv[2]);
+	    }
+	    if (TclGetString(objv[3])[0] == '\0') {
+		if (objc == 4) {
+		    return AliasDelete(interp, slaveInterp, objv[2]);
+		}
+	    } else {
+		return AliasCreate(interp, slaveInterp, interp, objv[2],
+			objv[3], objc - 4, objv + 4);
+	    }
+	}
+	Tcl_WrongNumArgs(interp, 2, objv, "aliasName ?targetName? ?arg ...?");
+	return TCL_ERROR;
+    case OPT_ALIASES:
+	if (objc != 2) {
+	    Tcl_WrongNumArgs(interp, 2, objv, NULL);
+	    return TCL_ERROR;
+	}
+	return AliasList(interp, slaveInterp);
+    case OPT_BGERROR:
+	if (objc != 2 && objc != 3) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "?cmdPrefix?");
+	    return TCL_ERROR;
+	}
+	return SlaveBgerror(interp, slaveInterp, objc - 2, objv + 2);
+    case OPT_DEBUG:
+	/*
+	 * TIP #378
+	 * Currently only -frame supported, otherwise ?-option ?value? ...?
+	 */
+	if (objc > 4) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "?-frame ?bool??");
+	    return TCL_ERROR;
+	}
+	return SlaveDebugCmd(interp, slaveInterp, objc - 2, objv + 2);
+    case OPT_EVAL:
+	if (objc < 3) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "arg ?arg ...?");
+	    return TCL_ERROR;
+	}
+	return SlaveEval(interp, slaveInterp, objc - 2, objv + 2);
+    case OPT_EXPOSE:
+	if ((objc < 3) || (objc > 4)) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "hiddenCmdName ?cmdName?");
+	    return TCL_ERROR;
+	}
+	return SlaveExpose(interp, slaveInterp, objc - 2, objv + 2);
+    case OPT_HIDE:
+	if ((objc < 3) || (objc > 4)) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "cmdName ?hiddenCmdName?");
+	    return TCL_ERROR;
+	}
+	return SlaveHide(interp, slaveInterp, objc - 2, objv + 2);
+    case OPT_HIDDEN:
+	if (objc != 2) {
+	    Tcl_WrongNumArgs(interp, 2, objv, NULL);
+	    return TCL_ERROR;
+	}
+	return SlaveHidden(interp, slaveInterp);
+    case OPT_ISSAFE:
+	if (objc != 2) {
+	    Tcl_WrongNumArgs(interp, 2, objv, NULL);
+	    return TCL_ERROR;
+	}
+	Tcl_SetObjResult(interp, Tcl_NewBooleanObj(Tcl_IsSafe(slaveInterp)));
+	return TCL_OK;
+    case OPT_INVOKEHIDDEN: {
+	int i;
+	const char *namespaceName;
+	static const char *const hiddenOptions[] = {
+	    "-global",	"-namespace",	"--", NULL
+	};
+	enum hiddenOption {
+	    OPT_GLOBAL,	OPT_NAMESPACE,	OPT_LAST
+	};
+
+	namespaceName = NULL;
+	for (i = 2; i < objc; i++) {
+	    if (TclGetString(objv[i])[0] != '-') {
+		break;
+	    }
+	    if (Tcl_GetIndexFromObj(interp, objv[i], hiddenOptions, "option",
+		    0, &index) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    if (index == OPT_GLOBAL) {
+		namespaceName = "::";
+	    } else if (index == OPT_NAMESPACE) {
+		if (++i == objc) { /* There must be more arguments. */
+		    break;
+		} else {
+		    namespaceName = TclGetString(objv[i]);
+		}
+	    } else {
+		i++;
+		break;
+	    }
+	}
+	if (objc - i < 1) {
+	    Tcl_WrongNumArgs(interp, 2, objv,
+		    "?-namespace ns? ?-global? ?--? cmd ?arg ..?");
+	    return TCL_ERROR;
+	}
+	return SlaveInvokeHidden(interp, slaveInterp, namespaceName,
+		objc - i, objv + i);
+    }
+    case OPT_LIMIT: {
+	static const char *const limitTypes[] = {
+	    "commands", "time", NULL
+	};
+	enum LimitTypes {
+	    LIMIT_TYPE_COMMANDS, LIMIT_TYPE_TIME
+	};
+	int limitType;
+
+	if (objc < 3) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "limitType ?-option value ...?");
+	    return TCL_ERROR;
+	}
+	if (Tcl_GetIndexFromObj(interp, objv[2], limitTypes, "limit type", 0,
+		&limitType) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	switch ((enum LimitTypes) limitType) {
+	case LIMIT_TYPE_COMMANDS:
+	    return SlaveCommandLimitCmd(interp, slaveInterp, 3, objc,objv);
+	case LIMIT_TYPE_TIME:
+	    return SlaveTimeLimitCmd(interp, slaveInterp, 3, objc, objv);
+	}
+    }
+    case OPT_MARKTRUSTED:
+	if (objc != 2) {
+	    Tcl_WrongNumArgs(interp, 2, objv, NULL);
+	    return TCL_ERROR;
+	}
+	return SlaveMarkTrusted(interp, slaveInterp);
+    case OPT_RECLIMIT:
+	if (objc != 2 && objc != 3) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "?newlimit?");
+	    return TCL_ERROR;
+	}
+	return SlaveRecursionLimit(interp, slaveInterp, objc - 2, objv + 2);
+    }
+
+    return TCL_ERROR;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveObjCmdDeleteProc --
+ *
+ *	Invoked when an object command for a slave interpreter is deleted;
+ *	cleans up all state associated with the slave interpreter and destroys
+ *	the slave interpreter.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Cleans up all state associated with the slave interpreter and destroys
+ *	the slave interpreter.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+SlaveObjCmdDeleteProc(
+    ClientData clientData)	/* The SlaveRecord for the command. */
+{
+    Slave *slavePtr;		/* Interim storage for Slave record. */
+    Tcl_Interp *slaveInterp = clientData;
+				/* And for a slave interp. */
+
+    slavePtr = &((InterpInfo *) ((Interp *) slaveInterp)->interpInfo)->slave;
+
+    /*
+     * Unlink the slave from its master interpreter.
+     */
+
+    Tcl_DeleteHashEntry(slavePtr->slaveEntryPtr);
+
+    /*
+     * Set to NULL so that when the InterpInfo is cleaned up in the slave it
+     * does not try to delete the command causing all sorts of grief. See
+     * SlaveRecordDeleteProc().
+     */
+
+    slavePtr->interpCmd = NULL;
+
+    if (slavePtr->slaveInterp != NULL) {
+	Tcl_DeleteInterp(slavePtr->slaveInterp);
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveDebugCmd -- TIP #378
+ *
+ *	Helper function to handle 'debug' command in a slave interpreter.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	May modify INTERP_DEBUG_FRAME flag in the slave.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveDebugCmd(
+    Tcl_Interp *interp,		/* Interp for error return. */
+    Tcl_Interp *slaveInterp,	/* The slave interpreter in which command
+				 * will be evaluated. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    static const char *const debugTypes[] = {
+	"-frame", NULL
+    };
+    enum DebugTypes {
+	DEBUG_TYPE_FRAME
+    };
+    int debugType;
+    Interp *iPtr;
+    Tcl_Obj *resultPtr;
+
+    iPtr = (Interp *) slaveInterp;
+    if (objc == 0) {
+	resultPtr = Tcl_NewObj();
+	Tcl_ListObjAppendElement(NULL, resultPtr,
+		Tcl_NewStringObj("-frame", -1));
+	Tcl_ListObjAppendElement(NULL, resultPtr,
+		Tcl_NewBooleanObj(iPtr->flags & INTERP_DEBUG_FRAME));
+	Tcl_SetObjResult(interp, resultPtr);
+    } else {
+	if (Tcl_GetIndexFromObj(interp, objv[0], debugTypes, "debug option",
+		0, &debugType) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	if (debugType == DEBUG_TYPE_FRAME) {
+	    if (objc == 2) { /* set */
+		if (Tcl_GetBooleanFromObj(interp, objv[1], &debugType)
+			!= TCL_OK) {
+		    return TCL_ERROR;
+		}
+
+		/*
+		 * Quietly ignore attempts to disable interp debugging.  This
+		 * is a one-way switch as frame debug info is maintained in a
+		 * stack that must be consistent once turned on.
+		 */
+
+		if (debugType) {
+		    iPtr->flags |= INTERP_DEBUG_FRAME;
+		}
+	    }
+	    Tcl_SetObjResult(interp,
+		    Tcl_NewBooleanObj(iPtr->flags & INTERP_DEBUG_FRAME));
+	}
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveEval --
+ *
+ *	Helper function to evaluate a command in a slave interpreter.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	Whatever the command does.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveEval(
+    Tcl_Interp *interp,		/* Interp for error return. */
+    Tcl_Interp *slaveInterp,	/* The slave interpreter in which command
+				 * will be evaluated. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    int result;
+
+    /*
+     * TIP #285: If necessary, reset the cancellation flags for the slave
+     * interpreter now; otherwise, canceling a script in a master interpreter
+     * can result in a situation where a slave interpreter can no longer
+     * evaluate any scripts unless somebody calls the TclResetCancellation
+     * function for that particular Tcl_Interp.
+     */
+
+    TclSetSlaveCancelFlags(slaveInterp, 0, 0);
+
+    Tcl_Preserve(slaveInterp);
+    Tcl_AllowExceptions(slaveInterp);
+
+    if (objc == 1) {
+	/*
+	 * TIP #280: Make actual argument location available to eval'd script.
+	 */
+
+	Interp *iPtr = (Interp *) interp;
+	CmdFrame *invoker = iPtr->cmdFramePtr;
+	int word = 0;
+
+	TclArgumentGet(interp, objv[0], &invoker, &word);
+
+	result = TclEvalObjEx(slaveInterp, objv[0], 0, invoker, word);
+    } else {
+	Tcl_Obj *objPtr = Tcl_ConcatObj(objc, objv);
+	Tcl_IncrRefCount(objPtr);
+	result = Tcl_EvalObjEx(slaveInterp, objPtr, 0);
+	Tcl_DecrRefCount(objPtr);
+    }
+    Tcl_TransferResult(slaveInterp, result, interp);
+
+    Tcl_Release(slaveInterp);
+    return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveExpose --
+ *
+ *	Helper function to expose a command in a slave interpreter.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	After this call scripts in the slave will be able to invoke the newly
+ *	exposed command.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveExpose(
+    Tcl_Interp *interp,		/* Interp for error return. */
+    Tcl_Interp *slaveInterp,	/* Interp in which command will be exposed. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument strings. */
+{
+    const char *name;
+
+    if (Tcl_IsSafe(interp)) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"permission denied: safe interpreter cannot expose commands",
+		-1));
+	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP", "UNSAFE",
+		NULL);
+	return TCL_ERROR;
+    }
+
+    name = TclGetString(objv[(objc == 1) ? 0 : 1]);
+    if (Tcl_ExposeCommand(slaveInterp, TclGetString(objv[0]),
+	    name) != TCL_OK) {
+	Tcl_TransferResult(slaveInterp, TCL_ERROR, interp);
+	return TCL_ERROR;
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveRecursionLimit --
+ *
+ *	Helper function to set/query the Recursion limit of an interp
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	When (objc == 1), slaveInterp will be set to a new recursion limit of
+ *	objv[0].
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveRecursionLimit(
+    Tcl_Interp *interp,		/* Interp for error return. */
+    Tcl_Interp *slaveInterp,	/* Interp in which limit is set/queried. */
+    int objc,			/* Set or Query. */
+    Tcl_Obj *const objv[])	/* Argument strings. */
+{
+    Interp *iPtr;
+    int limit;
+
+    if (objc) {
+	if (Tcl_IsSafe(interp)) {
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj("permission denied: "
+		    "safe interpreters cannot change recursion limit", -1));
+	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP", "UNSAFE",
+		    NULL);
+	    return TCL_ERROR;
+	}
+	if (TclGetIntFromObj(interp, objv[0], &limit) == TCL_ERROR) {
+	    return TCL_ERROR;
+	}
+	if (limit <= 0) {
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		    "recursion limit must be > 0", -1));
+	    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP", "BADLIMIT",
+		    NULL);
+	    return TCL_ERROR;
+	}
+	Tcl_SetRecursionLimit(slaveInterp, limit);
+	iPtr = (Interp *) slaveInterp;
+	if (interp == slaveInterp && iPtr->numLevels > limit) {
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		    "falling back due to new recursion limit", -1));
+	    Tcl_SetErrorCode(interp, "TCL", "RECURSION", NULL);
+	    return TCL_ERROR;
+	}
+	Tcl_SetObjResult(interp, objv[0]);
+	return TCL_OK;
+    } else {
+	limit = Tcl_SetRecursionLimit(slaveInterp, 0);
+	Tcl_SetObjResult(interp, Tcl_NewIntObj(limit));
+	return TCL_OK;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveHide --
+ *
+ *	Helper function to hide a command in a slave interpreter.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	After this call scripts in the slave will no longer be able to invoke
+ *	the named command.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveHide(
+    Tcl_Interp *interp,		/* Interp for error return. */
+    Tcl_Interp *slaveInterp,	/* Interp in which command will be exposed. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument strings. */
+{
+    const char *name;
+
+    if (Tcl_IsSafe(interp)) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"permission denied: safe interpreter cannot hide commands",
+		-1));
+	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP", "UNSAFE",
+		NULL);
+	return TCL_ERROR;
+    }
+
+    name = TclGetString(objv[(objc == 1) ? 0 : 1]);
+    if (Tcl_HideCommand(slaveInterp, TclGetString(objv[0]), name) != TCL_OK) {
+	Tcl_TransferResult(slaveInterp, TCL_ERROR, interp);
+	return TCL_ERROR;
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveHidden --
+ *
+ *	Helper function to compute list of hidden commands in a slave
+ *	interpreter.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveHidden(
+    Tcl_Interp *interp,		/* Interp for data return. */
+    Tcl_Interp *slaveInterp)	/* Interp whose hidden commands to query. */
+{
+    Tcl_Obj *listObjPtr = Tcl_NewObj();	/* Local object pointer. */
+    Tcl_HashTable *hTblPtr;		/* For local searches. */
+    Tcl_HashEntry *hPtr;		/* For local searches. */
+    Tcl_HashSearch hSearch;		/* For local searches. */
+
+    hTblPtr = ((Interp *) slaveInterp)->hiddenCmdTablePtr;
+    if (hTblPtr != NULL) {
+	for (hPtr = Tcl_FirstHashEntry(hTblPtr, &hSearch);
+		hPtr != NULL;
+		hPtr = Tcl_NextHashEntry(&hSearch)) {
+	    Tcl_ListObjAppendElement(NULL, listObjPtr,
+		    Tcl_NewStringObj(Tcl_GetHashKey(hTblPtr, hPtr), -1));
+	}
+    }
+    Tcl_SetObjResult(interp, listObjPtr);
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveInvokeHidden --
+ *
+ *	Helper function to invoke a hidden command in a slave interpreter.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	Whatever the hidden command does.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveInvokeHidden(
+    Tcl_Interp *interp,		/* Interp for error return. */
+    Tcl_Interp *slaveInterp,	/* The slave interpreter in which command will
+				 * be invoked. */
+    const char *namespaceName,	/* The namespace to use, if any. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    int result;
+
+    if (Tcl_IsSafe(interp)) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"not allowed to invoke hidden commands from safe interpreter",
+		-1));
+	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP", "UNSAFE",
+		NULL);
+	return TCL_ERROR;
+    }
+
+    Tcl_Preserve(slaveInterp);
+    Tcl_AllowExceptions(slaveInterp);
+
+    if (namespaceName == NULL) {
+	NRE_callback *rootPtr = TOP_CB(slaveInterp);
+
+	Tcl_NRAddCallback(interp, NRPostInvokeHidden, slaveInterp,
+		rootPtr, NULL, NULL);
+	return TclNRInvoke(NULL, slaveInterp, objc, objv);
+    } else {
+	Namespace *nsPtr, *dummy1, *dummy2;
+	const char *tail;
+
+	result = TclGetNamespaceForQualName(slaveInterp, namespaceName, NULL,
+		TCL_FIND_ONLY_NS | TCL_GLOBAL_ONLY | TCL_LEAVE_ERR_MSG
+		| TCL_CREATE_NS_IF_UNKNOWN, &nsPtr, &dummy1, &dummy2, &tail);
+	if (result == TCL_OK) {
+	    result = TclObjInvokeNamespace(slaveInterp, objc, objv,
+		    (Tcl_Namespace *) nsPtr, TCL_INVOKE_HIDDEN);
+	}
+    }
+
+    Tcl_TransferResult(slaveInterp, result, interp);
+
+    Tcl_Release(slaveInterp);
+    return result;
+}
+
+static int
+NRPostInvokeHidden(
+    ClientData data[],
+    Tcl_Interp *interp,
+    int result)
+{
+    Tcl_Interp *slaveInterp = (Tcl_Interp *)data[0];
+    NRE_callback *rootPtr = (NRE_callback *)data[1];
+
+    if (interp != slaveInterp) {
+	result = TclNRRunCallbacks(slaveInterp, result, rootPtr);
+	Tcl_TransferResult(slaveInterp, result, interp);
+    }
+    Tcl_Release(slaveInterp);
+    return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveMarkTrusted --
+ *
+ *	Helper function to mark a slave interpreter as trusted (unsafe).
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	After this call the hard-wired security checks in the core no longer
+ *	prevent the slave from performing certain operations.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveMarkTrusted(
+    Tcl_Interp *interp,		/* Interp for error return. */
+    Tcl_Interp *slaveInterp)	/* The slave interpreter which will be marked
+				 * trusted. */
+{
+    if (Tcl_IsSafe(interp)) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"permission denied: safe interpreter cannot mark trusted",
+		-1));
+	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP", "UNSAFE",
+		NULL);
+	return TCL_ERROR;
+    }
+    ((Interp *) slaveInterp)->flags &= ~SAFE_INTERP;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_IsSafe --
+ *
+ *	Determines whether an interpreter is safe
+ *
+ * Results:
+ *	1 if it is safe, 0 if it is not.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_IsSafe(
+    Tcl_Interp *interp)		/* Is this interpreter "safe" ? */
+{
+    Interp *iPtr = (Interp *) interp;
+
+    if (iPtr == NULL) {
+	return 0;
+    }
+    return (iPtr->flags & SAFE_INTERP) ? 1 : 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_MakeSafe --
+ *
+ *	Makes its argument interpreter contain only functionality that is
+ *	defined to be part of Safe Tcl. Unsafe commands are hidden, the env
+ *	array is unset, and the standard channels are removed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Hides commands in its argument interpreter, and removes settings and
+ *	channels.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_MakeSafe(
+    Tcl_Interp *interp)		/* Interpreter to be made safe. */
+{
+    Tcl_Channel chan;		/* Channel to remove from safe interpreter. */
+    Interp *iPtr = (Interp *) interp;
+    Tcl_Interp *master = ((InterpInfo*) iPtr->interpInfo)->slave.masterInterp;
+
+    TclHideUnsafeCommands(interp);
+
+    if (master != NULL) {
+	/*
+	 * Alias these function implementations in the slave to those in the
+	 * master; the overall implementations are safe, but they're normally
+	 * defined by init.tcl which is not sourced by safe interpreters.
+	 * Assume these functions all work. [Bug 2895741]
+	 */
+
+	(void) Tcl_Eval(interp,
+		"namespace eval ::tcl {namespace eval mathfunc {}}");
+	(void) Tcl_CreateAlias(interp, "::tcl::mathfunc::min", master,
+		"::tcl::mathfunc::min", 0, NULL);
+	(void) Tcl_CreateAlias(interp, "::tcl::mathfunc::max", master,
+		"::tcl::mathfunc::max", 0, NULL);
+    }
+
+    iPtr->flags |= SAFE_INTERP;
+
+    /*
+     * Unsetting variables : (which should not have been set in the first
+     * place, but...)
+     */
+
+    /*
+     * No env array in a safe slave.
+     */
+
+    Tcl_UnsetVar(interp, "env", TCL_GLOBAL_ONLY);
+
+    /*
+     * Remove unsafe parts of tcl_platform
+     */
+
+    Tcl_UnsetVar2(interp, "tcl_platform", "os", TCL_GLOBAL_ONLY);
+    Tcl_UnsetVar2(interp, "tcl_platform", "osVersion", TCL_GLOBAL_ONLY);
+    Tcl_UnsetVar2(interp, "tcl_platform", "machine", TCL_GLOBAL_ONLY);
+    Tcl_UnsetVar2(interp, "tcl_platform", "user", TCL_GLOBAL_ONLY);
+
+    /*
+     * Unset path informations variables (the only one remaining is [info
+     * nameofexecutable])
+     */
+
+    Tcl_UnsetVar(interp, "tclDefaultLibrary", TCL_GLOBAL_ONLY);
+    Tcl_UnsetVar(interp, "tcl_library", TCL_GLOBAL_ONLY);
+    Tcl_UnsetVar(interp, "tcl_pkgPath", TCL_GLOBAL_ONLY);
+
+    /*
+     * Remove the standard channels from the interpreter; safe interpreters do
+     * not ordinarily have access to stdin, stdout and stderr.
+     *
+     * NOTE: These channels are not added to the interpreter by the
+     * Tcl_CreateInterp call, but may be added later, by another I/O
+     * operation. We want to ensure that the interpreter does not have these
+     * channels even if it is being made safe after being used for some time..
+     */
+
+    chan = Tcl_GetStdChannel(TCL_STDIN);
+    if (chan != NULL) {
+	Tcl_UnregisterChannel(interp, chan);
+    }
+    chan = Tcl_GetStdChannel(TCL_STDOUT);
+    if (chan != NULL) {
+	Tcl_UnregisterChannel(interp, chan);
+    }
+    chan = Tcl_GetStdChannel(TCL_STDERR);
+    if (chan != NULL) {
+	Tcl_UnregisterChannel(interp, chan);
+    }
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitExceeded --
+ *
+ *	Tests whether any limit has been exceeded in the given interpreter
+ *	(i.e. whether the interpreter is currently unable to process further
+ *	scripts).
+ *
+ * Results:
+ *	A boolean value.
+ *
+ * Side effects:
+ *	None.
+ *
+ * Notes:
+ *	If you change this function, you MUST also update TclLimitExceeded() in
+ *	tclInt.h.
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_LimitExceeded(
+    Tcl_Interp *interp)
+{
+    register Interp *iPtr = (Interp *) interp;
+
+    return iPtr->limit.exceeded != 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitReady --
+ *
+ *	Find out whether any limit has been set on the interpreter, and if so
+ *	check whether the granularity of that limit is such that the full
+ *	limit check should be carried out.
+ *
+ * Results:
+ *	A boolean value that indicates whether to call Tcl_LimitCheck.
+ *
+ * Side effects:
+ *	Increments the limit granularity counter.
+ *
+ * Notes:
+ *	If you change this function, you MUST also update TclLimitReady() in
+ *	tclInt.h.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_LimitReady(
+    Tcl_Interp *interp)
+{
+    register Interp *iPtr = (Interp *) interp;
+
+    if (iPtr->limit.active != 0) {
+	register int ticker = ++iPtr->limit.granularityTicker;
+
+	if ((iPtr->limit.active & TCL_LIMIT_COMMANDS) &&
+		((iPtr->limit.cmdGranularity == 1) ||
+		    (ticker % iPtr->limit.cmdGranularity == 0))) {
+	    return 1;
+	}
+	if ((iPtr->limit.active & TCL_LIMIT_TIME) &&
+		((iPtr->limit.timeGranularity == 1) ||
+		    (ticker % iPtr->limit.timeGranularity == 0))) {
+	    return 1;
+	}
+    }
+    return 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitCheck --
+ *
+ *	Check all currently set limits in the interpreter (where permitted by
+ *	granularity). If a limit is exceeded, call its callbacks and, if the
+ *	limit is still exceeded after the callbacks have run, make the
+ *	interpreter generate an error that cannot be caught within the limited
+ *	interpreter.
+ *
+ * Results:
+ *	A Tcl result value (TCL_OK if no limit is exceeded, and TCL_ERROR if a
+ *	limit has been exceeded).
+ *
+ * Side effects:
+ *	May invoke system calls. May invoke other interpreters. May be
+ *	reentrant. May put the interpreter into a state where it can no longer
+ *	execute commands without outside intervention.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_LimitCheck(
+    Tcl_Interp *interp)
+{
+    Interp *iPtr = (Interp *) interp;
+    register int ticker = iPtr->limit.granularityTicker;
+
+    if (Tcl_InterpDeleted(interp)) {
+	return TCL_OK;
+    }
+
+    if ((iPtr->limit.active & TCL_LIMIT_COMMANDS) &&
+	    ((iPtr->limit.cmdGranularity == 1) ||
+		    (ticker % iPtr->limit.cmdGranularity == 0)) &&
+	    (iPtr->limit.cmdCount < iPtr->cmdCount)) {
+	iPtr->limit.exceeded |= TCL_LIMIT_COMMANDS;
+	Tcl_Preserve(interp);
+	RunLimitHandlers(iPtr->limit.cmdHandlers, interp);
+	if (iPtr->limit.cmdCount >= iPtr->cmdCount) {
+	    iPtr->limit.exceeded &= ~TCL_LIMIT_COMMANDS;
+	} else if (iPtr->limit.exceeded & TCL_LIMIT_COMMANDS) {
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		    "command count limit exceeded", -1));
+	    Tcl_SetErrorCode(interp, "TCL", "LIMIT", "COMMANDS", NULL);
+	    Tcl_Release(interp);
+	    return TCL_ERROR;
+	}
+	Tcl_Release(interp);
+    }
+
+    if ((iPtr->limit.active & TCL_LIMIT_TIME) &&
+	    ((iPtr->limit.timeGranularity == 1) ||
+		(ticker % iPtr->limit.timeGranularity == 0))) {
+	Tcl_Time now;
+
+	Tcl_GetTime(&now);
+	if (iPtr->limit.time.sec < now.sec ||
+		(iPtr->limit.time.sec == now.sec &&
+		iPtr->limit.time.usec < now.usec)) {
+	    iPtr->limit.exceeded |= TCL_LIMIT_TIME;
+	    Tcl_Preserve(interp);
+	    RunLimitHandlers(iPtr->limit.timeHandlers, interp);
+	    if (iPtr->limit.time.sec > now.sec ||
+		    (iPtr->limit.time.sec == now.sec &&
+		    iPtr->limit.time.usec >= now.usec)) {
+		iPtr->limit.exceeded &= ~TCL_LIMIT_TIME;
+	    } else if (iPtr->limit.exceeded & TCL_LIMIT_TIME) {
+		Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			"time limit exceeded", -1));
+		Tcl_SetErrorCode(interp, "TCL", "LIMIT", "TIME", NULL);
+		Tcl_Release(interp);
+		return TCL_ERROR;
+	    }
+	    Tcl_Release(interp);
+	}
+    }
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * RunLimitHandlers --
+ *
+ *	Invoke all the limit handlers in a list (for a particular limit).
+ *	Note that no particular limit handler callback will be invoked
+ *	reentrantly.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Depends on the limit handlers.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+RunLimitHandlers(
+    LimitHandler *handlerPtr,
+    Tcl_Interp *interp)
+{
+    LimitHandler *nextPtr;
+    for (; handlerPtr!=NULL ; handlerPtr=nextPtr) {
+	if (handlerPtr->flags & (LIMIT_HANDLER_DELETED|LIMIT_HANDLER_ACTIVE)) {
+	    /*
+	     * Reentrant call or something seriously strange in the delete
+	     * code.
+	     */
+
+	    nextPtr = handlerPtr->nextPtr;
+	    continue;
+	}
+
+	/*
+	 * Set the ACTIVE flag while running the limit handler itself so we
+	 * cannot reentrantly call this handler and know to use the alternate
+	 * method of deletion if necessary.
+	 */
+
+	handlerPtr->flags |= LIMIT_HANDLER_ACTIVE;
+	handlerPtr->handlerProc(handlerPtr->clientData, interp);
+	handlerPtr->flags &= ~LIMIT_HANDLER_ACTIVE;
+
+	/*
+	 * Rediscover this value; it might have changed during the processing
+	 * of a limit handler. We have to record it here because we might
+	 * delete the structure below, and reading a value out of a deleted
+	 * structure is unsafe (even if actually legal with some
+	 * malloc()/free() implementations.)
+	 */
+
+	nextPtr = handlerPtr->nextPtr;
+
+	/*
+	 * If we deleted the current handler while we were executing it, we
+	 * will have spliced it out of the list and set the
+	 * LIMIT_HANDLER_DELETED flag.
+	 */
+
+	if (handlerPtr->flags & LIMIT_HANDLER_DELETED) {
+	    if (handlerPtr->deleteProc != NULL) {
+		handlerPtr->deleteProc(handlerPtr->clientData);
+	    }
+	    ckfree(handlerPtr);
+	}
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitAddHandler --
+ *
+ *	Add a callback handler for a particular resource limit.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Extends the internal linked list of handlers for a limit.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_LimitAddHandler(
+    Tcl_Interp *interp,
+    int type,
+    Tcl_LimitHandlerProc *handlerProc,
+    ClientData clientData,
+    Tcl_LimitHandlerDeleteProc *deleteProc)
+{
+    Interp *iPtr = (Interp *) interp;
+    LimitHandler *handlerPtr;
+
+    /*
+     * Convert everything into a real deletion callback.
+     */
+
+    if (deleteProc == (Tcl_LimitHandlerDeleteProc *) TCL_DYNAMIC) {
+	deleteProc = (Tcl_LimitHandlerDeleteProc *) Tcl_Free;
+    }
+    if (deleteProc == (Tcl_LimitHandlerDeleteProc *) TCL_STATIC) {
+	deleteProc = NULL;
+    }
+
+    /*
+     * Allocate a handler record.
+     */
+
+    handlerPtr = ckalloc(sizeof(LimitHandler));
+    handlerPtr->flags = 0;
+    handlerPtr->handlerProc = handlerProc;
+    handlerPtr->clientData = clientData;
+    handlerPtr->deleteProc = deleteProc;
+    handlerPtr->prevPtr = NULL;
+
+    /*
+     * Prepend onto the front of the correct linked list.
+     */
+
+    switch (type) {
+    case TCL_LIMIT_COMMANDS:
+	handlerPtr->nextPtr = iPtr->limit.cmdHandlers;
+	if (handlerPtr->nextPtr != NULL) {
+	    handlerPtr->nextPtr->prevPtr = handlerPtr;
+	}
+	iPtr->limit.cmdHandlers = handlerPtr;
+	return;
+
+    case TCL_LIMIT_TIME:
+	handlerPtr->nextPtr = iPtr->limit.timeHandlers;
+	if (handlerPtr->nextPtr != NULL) {
+	    handlerPtr->nextPtr->prevPtr = handlerPtr;
+	}
+	iPtr->limit.timeHandlers = handlerPtr;
+	return;
+    }
+
+    Tcl_Panic("unknown type of resource limit");
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitRemoveHandler --
+ *
+ *	Remove a callback handler for a particular resource limit.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The handler is spliced out of the internal linked list for the limit,
+ *	and if not currently being invoked, deleted. Otherwise it is just
+ *	marked for deletion and removed when the limit handler has finished
+ *	executing.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_LimitRemoveHandler(
+    Tcl_Interp *interp,
+    int type,
+    Tcl_LimitHandlerProc *handlerProc,
+    ClientData clientData)
+{
+    Interp *iPtr = (Interp *) interp;
+    LimitHandler *handlerPtr;
+
+    switch (type) {
+    case TCL_LIMIT_COMMANDS:
+	handlerPtr = iPtr->limit.cmdHandlers;
+	break;
+    case TCL_LIMIT_TIME:
+	handlerPtr = iPtr->limit.timeHandlers;
+	break;
+    default:
+	Tcl_Panic("unknown type of resource limit");
+	return;
+    }
+
+    for (; handlerPtr!=NULL ; handlerPtr=handlerPtr->nextPtr) {
+	if ((handlerPtr->handlerProc != handlerProc) ||
+		(handlerPtr->clientData != clientData)) {
+	    continue;
+	}
+
+	/*
+	 * We've found the handler to delete; mark it as doomed if not already
+	 * so marked (which shouldn't actually happen).
+	 */
+
+	if (handlerPtr->flags & LIMIT_HANDLER_DELETED) {
+	    return;
+	}
+	handlerPtr->flags |= LIMIT_HANDLER_DELETED;
+
+	/*
+	 * Splice the handler out of the doubly-linked list.
+	 */
+
+	if (handlerPtr->prevPtr == NULL) {
+	    switch (type) {
+	    case TCL_LIMIT_COMMANDS:
+		iPtr->limit.cmdHandlers = handlerPtr->nextPtr;
+		break;
+	    case TCL_LIMIT_TIME:
+		iPtr->limit.timeHandlers = handlerPtr->nextPtr;
+		break;
+	    }
+	} else {
+	    handlerPtr->prevPtr->nextPtr = handlerPtr->nextPtr;
+	}
+	if (handlerPtr->nextPtr != NULL) {
+	    handlerPtr->nextPtr->prevPtr = handlerPtr->prevPtr;
+	}
+
+	/*
+	 * If nothing is currently executing the handler, delete its client
+	 * data and the overall handler structure now. Otherwise it will all
+	 * go away when the handler returns.
+	 */
+
+	if (!(handlerPtr->flags & LIMIT_HANDLER_ACTIVE)) {
+	    if (handlerPtr->deleteProc != NULL) {
+		handlerPtr->deleteProc(handlerPtr->clientData);
+	    }
+	    ckfree(handlerPtr);
+	}
+	return;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclLimitRemoveAllHandlers --
+ *
+ *	Remove all limit callback handlers for an interpreter. This is invoked
+ *	as part of deleting the interpreter.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Limit handlers are deleted or marked for deletion (as with
+ *	Tcl_LimitRemoveHandler).
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclLimitRemoveAllHandlers(
+    Tcl_Interp *interp)
+{
+    Interp *iPtr = (Interp *) interp;
+    LimitHandler *handlerPtr, *nextHandlerPtr;
+
+    /*
+     * Delete all command-limit handlers.
+     */
+
+    for (handlerPtr=iPtr->limit.cmdHandlers, iPtr->limit.cmdHandlers=NULL;
+	    handlerPtr!=NULL; handlerPtr=nextHandlerPtr) {
+	nextHandlerPtr = handlerPtr->nextPtr;
+
+	/*
+	 * Do not delete here if it has already been marked for deletion.
+	 */
+
+	if (handlerPtr->flags & LIMIT_HANDLER_DELETED) {
+	    continue;
+	}
+	handlerPtr->flags |= LIMIT_HANDLER_DELETED;
+	handlerPtr->prevPtr = NULL;
+	handlerPtr->nextPtr = NULL;
+
+	/*
+	 * If nothing is currently executing the handler, delete its client
+	 * data and the overall handler structure now. Otherwise it will all
+	 * go away when the handler returns.
+	 */
+
+	if (!(handlerPtr->flags & LIMIT_HANDLER_ACTIVE)) {
+	    if (handlerPtr->deleteProc != NULL) {
+		handlerPtr->deleteProc(handlerPtr->clientData);
+	    }
+	    ckfree(handlerPtr);
+	}
+    }
+
+    /*
+     * Delete all time-limit handlers.
+     */
+
+    for (handlerPtr=iPtr->limit.timeHandlers, iPtr->limit.timeHandlers=NULL;
+	    handlerPtr!=NULL; handlerPtr=nextHandlerPtr) {
+	nextHandlerPtr = handlerPtr->nextPtr;
+
+	/*
+	 * Do not delete here if it has already been marked for deletion.
+	 */
+
+	if (handlerPtr->flags & LIMIT_HANDLER_DELETED) {
+	    continue;
+	}
+	handlerPtr->flags |= LIMIT_HANDLER_DELETED;
+	handlerPtr->prevPtr = NULL;
+	handlerPtr->nextPtr = NULL;
+
+	/*
+	 * If nothing is currently executing the handler, delete its client
+	 * data and the overall handler structure now. Otherwise it will all
+	 * go away when the handler returns.
+	 */
+
+	if (!(handlerPtr->flags & LIMIT_HANDLER_ACTIVE)) {
+	    if (handlerPtr->deleteProc != NULL) {
+		handlerPtr->deleteProc(handlerPtr->clientData);
+	    }
+	    ckfree(handlerPtr);
+	}
+    }
+
+    /*
+     * Delete the timer callback that is used to trap limits that occur in
+     * [vwait]s...
+     */
+
+    if (iPtr->limit.timeEvent != NULL) {
+	Tcl_DeleteTimerHandler(iPtr->limit.timeEvent);
+	iPtr->limit.timeEvent = NULL;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitTypeEnabled --
+ *
+ *	Check whether a particular limit has been enabled for an interpreter.
+ *
+ * Results:
+ *	A boolean value.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_LimitTypeEnabled(
+    Tcl_Interp *interp,
+    int type)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    return (iPtr->limit.active & type) != 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitTypeExceeded --
+ *
+ *	Check whether a particular limit has been exceeded for an interpreter.
+ *
+ * Results:
+ *	A boolean value (note that Tcl_LimitExceeded will always return
+ *	non-zero when this function returns non-zero).
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_LimitTypeExceeded(
+    Tcl_Interp *interp,
+    int type)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    return (iPtr->limit.exceeded & type) != 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitTypeSet --
+ *
+ *	Enable a particular limit for an interpreter.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The limit is turned on and will be checked in future at an interval
+ *	determined by the frequency of calling of Tcl_LimitReady and the
+ *	granularity of the limit in question.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_LimitTypeSet(
+    Tcl_Interp *interp,
+    int type)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    iPtr->limit.active |= type;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitTypeReset --
+ *
+ *	Disable a particular limit for an interpreter.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The limit is disabled. If the limit was exceeded when this function
+ *	was called, the limit will no longer be exceeded afterwards and the
+ *	interpreter will be free to execute further scripts (assuming it isn't
+ *	also deleted, of course).
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_LimitTypeReset(
+    Tcl_Interp *interp,
+    int type)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    iPtr->limit.active &= ~type;
+    iPtr->limit.exceeded &= ~type;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitSetCommands --
+ *
+ *	Set the command limit for an interpreter.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Also resets whether the command limit was exceeded. This might permit
+ *	a small amount of further execution in the interpreter even if the
+ *	limit itself is theoretically exceeded.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_LimitSetCommands(
+    Tcl_Interp *interp,
+    int commandLimit)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    iPtr->limit.cmdCount = commandLimit;
+    iPtr->limit.exceeded &= ~TCL_LIMIT_COMMANDS;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitGetCommands --
+ *
+ *	Get the number of commands that may be executed in the interpreter
+ *	before the command-limit is reached.
+ *
+ * Results:
+ *	An upper bound on the number of commands.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_LimitGetCommands(
+    Tcl_Interp *interp)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    return iPtr->limit.cmdCount;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitSetTime --
+ *
+ *	Set the time limit for an interpreter by copying it from the value
+ *	pointed to by the timeLimitPtr argument.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Also resets whether the time limit was exceeded. This might permit a
+ *	small amount of further execution in the interpreter even if the limit
+ *	itself is theoretically exceeded.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_LimitSetTime(
+    Tcl_Interp *interp,
+    Tcl_Time *timeLimitPtr)
+{
+    Interp *iPtr = (Interp *) interp;
+    Tcl_Time nextMoment;
+
+    memcpy(&iPtr->limit.time, timeLimitPtr, sizeof(Tcl_Time));
+    if (iPtr->limit.timeEvent != NULL) {
+	Tcl_DeleteTimerHandler(iPtr->limit.timeEvent);
+    }
+    nextMoment.sec = timeLimitPtr->sec;
+    nextMoment.usec = timeLimitPtr->usec+10;
+    if (nextMoment.usec >= 1000000) {
+	nextMoment.sec++;
+	nextMoment.usec -= 1000000;
+    }
+    iPtr->limit.timeEvent = TclCreateAbsoluteTimerHandler(&nextMoment,
+	    TimeLimitCallback, interp);
+    iPtr->limit.exceeded &= ~TCL_LIMIT_TIME;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TimeLimitCallback --
+ *
+ *	Callback that allows time limits to be enforced even when doing a
+ *	blocking wait for events.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	May put the interpreter into a state where it can no longer execute
+ *	commands. May make callbacks into other interpreters.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+TimeLimitCallback(
+    ClientData clientData)
+{
+    Tcl_Interp *interp = clientData;
+    Interp *iPtr = clientData;
+    int code;
+
+    Tcl_Preserve(interp);
+    iPtr->limit.timeEvent = NULL;
+
+    /*
+     * Must reset the granularity ticker here to force an immediate full
+     * check. This is OK because we're swallowing the cost in the overall cost
+     * of the event loop. [Bug 2891362]
+     */
+
+    iPtr->limit.granularityTicker = 0;
+
+    code = Tcl_LimitCheck(interp);
+    if (code != TCL_OK) {
+	Tcl_AddErrorInfo(interp, "\n    (while waiting for event)");
+	Tcl_BackgroundException(interp, code);
+    }
+    Tcl_Release(interp);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitGetTime --
+ *
+ *	Get the current time limit.
+ *
+ * Results:
+ *	The time limit (by it being copied into the variable pointed to by the
+ *	timeLimitPtr).
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_LimitGetTime(
+    Tcl_Interp *interp,
+    Tcl_Time *timeLimitPtr)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    memcpy(timeLimitPtr, &iPtr->limit.time, sizeof(Tcl_Time));
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitSetGranularity --
+ *
+ *	Set the granularity divisor (which must be positive) for a particular
+ *	limit.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The granularity is updated.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_LimitSetGranularity(
+    Tcl_Interp *interp,
+    int type,
+    int granularity)
+{
+    Interp *iPtr = (Interp *) interp;
+    if (granularity < 1) {
+	Tcl_Panic("limit granularity must be positive");
+    }
+
+    switch (type) {
+    case TCL_LIMIT_COMMANDS:
+	iPtr->limit.cmdGranularity = granularity;
+	return;
+    case TCL_LIMIT_TIME:
+	iPtr->limit.timeGranularity = granularity;
+	return;
+    }
+    Tcl_Panic("unknown type of resource limit");
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_LimitGetGranularity --
+ *
+ *	Get the granularity divisor for a particular limit.
+ *
+ * Results:
+ *	The granularity divisor for the given limit.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_LimitGetGranularity(
+    Tcl_Interp *interp,
+    int type)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    switch (type) {
+    case TCL_LIMIT_COMMANDS:
+	return iPtr->limit.cmdGranularity;
+    case TCL_LIMIT_TIME:
+	return iPtr->limit.timeGranularity;
+    }
+    Tcl_Panic("unknown type of resource limit");
+    return -1; /* NOT REACHED */
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * DeleteScriptLimitCallback --
+ *
+ *	Callback for when a script limit (a limit callback implemented as a
+ *	Tcl script in a master interpreter, as set up from Tcl) is deleted.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The reference to the script callback from the controlling interpreter
+ *	is removed.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+DeleteScriptLimitCallback(
+    ClientData clientData)
+{
+    ScriptLimitCallback *limitCBPtr = clientData;
+
+    Tcl_DecrRefCount(limitCBPtr->scriptObj);
+    if (limitCBPtr->entryPtr != NULL) {
+	Tcl_DeleteHashEntry(limitCBPtr->entryPtr);
+    }
+    ckfree(limitCBPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * CallScriptLimitCallback --
+ *
+ *	Invoke a script limit callback. Used to implement limit callbacks set
+ *	at the Tcl level on child interpreters.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Depends on the callback script. Errors are reported as background
+ *	errors.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+CallScriptLimitCallback(
+    ClientData clientData,
+    Tcl_Interp *interp)		/* Interpreter which failed the limit */
+{
+    ScriptLimitCallback *limitCBPtr = clientData;
+    int code;
+
+    if (Tcl_InterpDeleted(limitCBPtr->interp)) {
+	return;
+    }
+    Tcl_Preserve(limitCBPtr->interp);
+    code = Tcl_EvalObjEx(limitCBPtr->interp, limitCBPtr->scriptObj,
+	    TCL_EVAL_GLOBAL);
+    if (code != TCL_OK && !Tcl_InterpDeleted(limitCBPtr->interp)) {
+	Tcl_BackgroundException(limitCBPtr->interp, code);
+    }
+    Tcl_Release(limitCBPtr->interp);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SetScriptLimitCallback --
+ *
+ *	Install (or remove, if scriptObj is NULL) a limit callback script that
+ *	is called when the target interpreter exceeds the type of limit
+ *	specified. Each interpreter may only have one callback set on another
+ *	interpreter through this mechanism (though as many interpreters may be
+ *	limited as the programmer chooses overall).
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	A limit callback implemented as an invokation of a Tcl script in
+ *	another interpreter is either installed or removed.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+SetScriptLimitCallback(
+    Tcl_Interp *interp,
+    int type,
+    Tcl_Interp *targetInterp,
+    Tcl_Obj *scriptObj)
+{
+    ScriptLimitCallback *limitCBPtr;
+    Tcl_HashEntry *hashPtr;
+    int isNew;
+    ScriptLimitCallbackKey key;
+    Interp *iPtr = (Interp *) interp;
+
+    if (interp == targetInterp) {
+	Tcl_Panic("installing limit callback to the limited interpreter");
+    }
+
+    key.interp = targetInterp;
+    key.type = type;
+
+    if (scriptObj == NULL) {
+	hashPtr = Tcl_FindHashEntry(&iPtr->limit.callbacks, (char *) &key);
+	if (hashPtr != NULL) {
+	    Tcl_LimitRemoveHandler(targetInterp, type, CallScriptLimitCallback,
+		    Tcl_GetHashValue(hashPtr));
+	}
+	return;
+    }
+
+    hashPtr = Tcl_CreateHashEntry(&iPtr->limit.callbacks, &key,
+	    &isNew);
+    if (!isNew) {
+	limitCBPtr = Tcl_GetHashValue(hashPtr);
+	limitCBPtr->entryPtr = NULL;
+	Tcl_LimitRemoveHandler(targetInterp, type, CallScriptLimitCallback,
+		limitCBPtr);
+    }
+
+    limitCBPtr = ckalloc(sizeof(ScriptLimitCallback));
+    limitCBPtr->interp = interp;
+    limitCBPtr->scriptObj = scriptObj;
+    limitCBPtr->entryPtr = hashPtr;
+    limitCBPtr->type = type;
+    Tcl_IncrRefCount(scriptObj);
+
+    Tcl_LimitAddHandler(targetInterp, type, CallScriptLimitCallback,
+	    limitCBPtr, DeleteScriptLimitCallback);
+    Tcl_SetHashValue(hashPtr, limitCBPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclRemoveScriptLimitCallbacks --
+ *
+ *	Remove all script-implemented limit callbacks that make calls back
+ *	into the given interpreter. This invoked as part of deleting an
+ *	interpreter.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The script limit callbacks are removed or marked for later removal.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclRemoveScriptLimitCallbacks(
+    Tcl_Interp *interp)
+{
+    Interp *iPtr = (Interp *) interp;
+    Tcl_HashEntry *hashPtr;
+    Tcl_HashSearch search;
+    ScriptLimitCallbackKey *keyPtr;
+
+    hashPtr = Tcl_FirstHashEntry(&iPtr->limit.callbacks, &search);
+    while (hashPtr != NULL) {
+	keyPtr = (ScriptLimitCallbackKey *)
+		Tcl_GetHashKey(&iPtr->limit.callbacks, hashPtr);
+	Tcl_LimitRemoveHandler(keyPtr->interp, keyPtr->type,
+		CallScriptLimitCallback, Tcl_GetHashValue(hashPtr));
+	hashPtr = Tcl_NextHashEntry(&search);
+    }
+    Tcl_DeleteHashTable(&iPtr->limit.callbacks);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclInitLimitSupport --
+ *
+ *	Initialise all the parts of the interpreter relating to resource limit
+ *	management. This allows an interpreter to both have limits set upon
+ *	itself and set limits upon other interpreters.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The resource limit subsystem is initialised for the interpreter.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclInitLimitSupport(
+    Tcl_Interp *interp)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    iPtr->limit.active = 0;
+    iPtr->limit.granularityTicker = 0;
+    iPtr->limit.exceeded = 0;
+    iPtr->limit.cmdCount = 0;
+    iPtr->limit.cmdHandlers = NULL;
+    iPtr->limit.cmdGranularity = 1;
+    memset(&iPtr->limit.time, 0, sizeof(Tcl_Time));
+    iPtr->limit.timeHandlers = NULL;
+    iPtr->limit.timeEvent = NULL;
+    iPtr->limit.timeGranularity = 10;
+    Tcl_InitHashTable(&iPtr->limit.callbacks,
+	    sizeof(ScriptLimitCallbackKey)/sizeof(int));
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * InheritLimitsFromMaster --
+ *
+ *	Derive the interpreter limit configuration for a slave interpreter
+ *	from the limit config for the master.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The slave interpreter limits are set so that if the master has a
+ *	limit, it may not exceed it by handing off work to slave interpreters.
+ *	Note that this does not transfer limit callbacks from the master to
+ *	the slave.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+InheritLimitsFromMaster(
+    Tcl_Interp *slaveInterp,
+    Tcl_Interp *masterInterp)
+{
+    Interp *slavePtr = (Interp *) slaveInterp;
+    Interp *masterPtr = (Interp *) masterInterp;
+
+    if (masterPtr->limit.active & TCL_LIMIT_COMMANDS) {
+	slavePtr->limit.active |= TCL_LIMIT_COMMANDS;
+	slavePtr->limit.cmdCount = 0;
+	slavePtr->limit.cmdGranularity = masterPtr->limit.cmdGranularity;
+    }
+    if (masterPtr->limit.active & TCL_LIMIT_TIME) {
+	slavePtr->limit.active |= TCL_LIMIT_TIME;
+	memcpy(&slavePtr->limit.time, &masterPtr->limit.time,
+		sizeof(Tcl_Time));
+	slavePtr->limit.timeGranularity = masterPtr->limit.timeGranularity;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveCommandLimitCmd --
+ *
+ *	Implementation of the [interp limit $i commands] and [$i limit
+ *	commands] subcommands. See the interp manual page for a full
+ *	description.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	Depends on the arguments.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveCommandLimitCmd(
+    Tcl_Interp *interp,		/* Current interpreter. */
+    Tcl_Interp *slaveInterp,	/* Interpreter being adjusted. */
+    int consumedObjc,		/* Number of args already parsed. */
+    int objc,			/* Total number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    static const char *const options[] = {
+	"-command", "-granularity", "-value", NULL
+    };
+    enum Options {
+	OPT_CMD, OPT_GRAN, OPT_VAL
+    };
+    Interp *iPtr = (Interp *) interp;
+    int index;
+    ScriptLimitCallbackKey key;
+    ScriptLimitCallback *limitCBPtr;
+    Tcl_HashEntry *hPtr;
+
+    /*
+     * First, ensure that we are not reading or writing the calling
+     * interpreter's limits; it may only manipulate its children. Note that
+     * the low level API enforces this with Tcl_Panic, which we want to
+     * avoid. [Bug 3398794]
+     */
+
+    if (interp == slaveInterp) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"limits on current interpreter inaccessible", -1));
+	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP", "SELF", NULL);
+	return TCL_ERROR;
+    }
+
+    if (objc == consumedObjc) {
+	Tcl_Obj *dictPtr;
+
+	TclNewObj(dictPtr);
+	key.interp = slaveInterp;
+	key.type = TCL_LIMIT_COMMANDS;
+	hPtr = Tcl_FindHashEntry(&iPtr->limit.callbacks, (char *) &key);
+	if (hPtr != NULL) {
+	    limitCBPtr = Tcl_GetHashValue(hPtr);
+	    if (limitCBPtr != NULL && limitCBPtr->scriptObj != NULL) {
+		Tcl_DictObjPut(NULL, dictPtr, Tcl_NewStringObj(options[0], -1),
+			limitCBPtr->scriptObj);
+	    } else {
+		goto putEmptyCommandInDict;
+	    }
+	} else {
+	    Tcl_Obj *empty;
+
+	putEmptyCommandInDict:
+	    TclNewObj(empty);
+	    Tcl_DictObjPut(NULL, dictPtr,
+		    Tcl_NewStringObj(options[0], -1), empty);
+	}
+	Tcl_DictObjPut(NULL, dictPtr, Tcl_NewStringObj(options[1], -1),
+		Tcl_NewIntObj(Tcl_LimitGetGranularity(slaveInterp,
+		TCL_LIMIT_COMMANDS)));
+
+	if (Tcl_LimitTypeEnabled(slaveInterp, TCL_LIMIT_COMMANDS)) {
+	    Tcl_DictObjPut(NULL, dictPtr, Tcl_NewStringObj(options[2], -1),
+		    Tcl_NewIntObj(Tcl_LimitGetCommands(slaveInterp)));
+	} else {
+	    Tcl_Obj *empty;
+
+	    TclNewObj(empty);
+	    Tcl_DictObjPut(NULL, dictPtr,
+		    Tcl_NewStringObj(options[2], -1), empty);
+	}
+	Tcl_SetObjResult(interp, dictPtr);
+	return TCL_OK;
+    } else if (objc == consumedObjc+1) {
+	if (Tcl_GetIndexFromObj(interp, objv[consumedObjc], options, "option",
+		0, &index) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	switch ((enum Options) index) {
+	case OPT_CMD:
+	    key.interp = slaveInterp;
+	    key.type = TCL_LIMIT_COMMANDS;
+	    hPtr = Tcl_FindHashEntry(&iPtr->limit.callbacks, (char *) &key);
+	    if (hPtr != NULL) {
+		limitCBPtr = Tcl_GetHashValue(hPtr);
+		if (limitCBPtr != NULL && limitCBPtr->scriptObj != NULL) {
+		    Tcl_SetObjResult(interp, limitCBPtr->scriptObj);
+		}
+	    }
+	    break;
+	case OPT_GRAN:
+	    Tcl_SetObjResult(interp, Tcl_NewIntObj(
+		    Tcl_LimitGetGranularity(slaveInterp, TCL_LIMIT_COMMANDS)));
+	    break;
+	case OPT_VAL:
+	    if (Tcl_LimitTypeEnabled(slaveInterp, TCL_LIMIT_COMMANDS)) {
+		Tcl_SetObjResult(interp,
+			Tcl_NewIntObj(Tcl_LimitGetCommands(slaveInterp)));
+	    }
+	    break;
+	}
+	return TCL_OK;
+    } else if ((objc-consumedObjc) & 1 /* isOdd(objc-consumedObjc) */) {
+	Tcl_WrongNumArgs(interp, consumedObjc, objv, "?-option value ...?");
+	return TCL_ERROR;
+    } else {
+	int i, scriptLen = 0, limitLen = 0;
+	Tcl_Obj *scriptObj = NULL, *granObj = NULL, *limitObj = NULL;
+	int gran = 0, limit = 0;
+
+	for (i=consumedObjc ; i<objc ; i+=2) {
+	    if (Tcl_GetIndexFromObj(interp, objv[i], options, "option", 0,
+		    &index) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    switch ((enum Options) index) {
+	    case OPT_CMD:
+		scriptObj = objv[i+1];
+		(void) Tcl_GetStringFromObj(objv[i+1], &scriptLen);
+		break;
+	    case OPT_GRAN:
+		granObj = objv[i+1];
+		if (TclGetIntFromObj(interp, objv[i+1], &gran) != TCL_OK) {
+		    return TCL_ERROR;
+		}
+		if (gran < 1) {
+		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			    "granularity must be at least 1", -1));
+		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+			    "BADVALUE", NULL);
+		    return TCL_ERROR;
+		}
+		break;
+	    case OPT_VAL:
+		limitObj = objv[i+1];
+		(void) Tcl_GetStringFromObj(objv[i+1], &limitLen);
+		if (limitLen == 0) {
+		    break;
+		}
+		if (TclGetIntFromObj(interp, objv[i+1], &limit) != TCL_OK) {
+		    return TCL_ERROR;
+		}
+		if (limit < 0) {
+		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			    "command limit value must be at least 0", -1));
+		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+			    "BADVALUE", NULL);
+		    return TCL_ERROR;
+		}
+		break;
+	    }
+	}
+	if (scriptObj != NULL) {
+	    SetScriptLimitCallback(interp, TCL_LIMIT_COMMANDS, slaveInterp,
+		    (scriptLen > 0 ? scriptObj : NULL));
+	}
+	if (granObj != NULL) {
+	    Tcl_LimitSetGranularity(slaveInterp, TCL_LIMIT_COMMANDS, gran);
+	}
+	if (limitObj != NULL) {
+	    if (limitLen > 0) {
+		Tcl_LimitSetCommands(slaveInterp, limit);
+		Tcl_LimitTypeSet(slaveInterp, TCL_LIMIT_COMMANDS);
+	    } else {
+		Tcl_LimitTypeReset(slaveInterp, TCL_LIMIT_COMMANDS);
+	    }
+	}
+	return TCL_OK;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * SlaveTimeLimitCmd --
+ *
+ *	Implementation of the [interp limit $i time] and [$i limit time]
+ *	subcommands. See the interp manual page for a full description.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	Depends on the arguments.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveTimeLimitCmd(
+    Tcl_Interp *interp,			/* Current interpreter. */
+    Tcl_Interp *slaveInterp,		/* Interpreter being adjusted. */
+    int consumedObjc,			/* Number of args already parsed. */
+    int objc,				/* Total number of arguments. */
+    Tcl_Obj *const objv[])		/* Argument objects. */
+{
+    static const char *const options[] = {
+	"-command", "-granularity", "-milliseconds", "-seconds", NULL
+    };
+    enum Options {
+	OPT_CMD, OPT_GRAN, OPT_MILLI, OPT_SEC
+    };
+    Interp *iPtr = (Interp *) interp;
+    int index;
+    ScriptLimitCallbackKey key;
+    ScriptLimitCallback *limitCBPtr;
+    Tcl_HashEntry *hPtr;
+
+    /*
+     * First, ensure that we are not reading or writing the calling
+     * interpreter's limits; it may only manipulate its children. Note that
+     * the low level API enforces this with Tcl_Panic, which we want to
+     * avoid. [Bug 3398794]
+     */
+
+    if (interp == slaveInterp) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"limits on current interpreter inaccessible", -1));
+	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP", "SELF", NULL);
+	return TCL_ERROR;
+    }
+
+    if (objc == consumedObjc) {
+	Tcl_Obj *dictPtr;
+
+	TclNewObj(dictPtr);
+	key.interp = slaveInterp;
+	key.type = TCL_LIMIT_TIME;
+	hPtr = Tcl_FindHashEntry(&iPtr->limit.callbacks, (char *) &key);
+	if (hPtr != NULL) {
+	    limitCBPtr = Tcl_GetHashValue(hPtr);
+	    if (limitCBPtr != NULL && limitCBPtr->scriptObj != NULL) {
+		Tcl_DictObjPut(NULL, dictPtr, Tcl_NewStringObj(options[0], -1),
+			limitCBPtr->scriptObj);
+	    } else {
+		goto putEmptyCommandInDict;
+	    }
+	} else {
+	    Tcl_Obj *empty;
+	putEmptyCommandInDict:
+	    TclNewObj(empty);
+	    Tcl_DictObjPut(NULL, dictPtr,
+		    Tcl_NewStringObj(options[0], -1), empty);
+	}
+	Tcl_DictObjPut(NULL, dictPtr, Tcl_NewStringObj(options[1], -1),
+		Tcl_NewIntObj(Tcl_LimitGetGranularity(slaveInterp,
+		TCL_LIMIT_TIME)));
+
+	if (Tcl_LimitTypeEnabled(slaveInterp, TCL_LIMIT_TIME)) {
+	    Tcl_Time limitMoment;
+
+	    Tcl_LimitGetTime(slaveInterp, &limitMoment);
+	    Tcl_DictObjPut(NULL, dictPtr, Tcl_NewStringObj(options[2], -1),
+		    Tcl_NewLongObj(limitMoment.usec/1000));
+	    Tcl_DictObjPut(NULL, dictPtr, Tcl_NewStringObj(options[3], -1),
+		    Tcl_NewLongObj(limitMoment.sec));
+	} else {
+	    Tcl_Obj *empty;
+
+	    TclNewObj(empty);
+	    Tcl_DictObjPut(NULL, dictPtr,
+		    Tcl_NewStringObj(options[2], -1), empty);
+	    Tcl_DictObjPut(NULL, dictPtr,
+		    Tcl_NewStringObj(options[3], -1), empty);
+	}
+	Tcl_SetObjResult(interp, dictPtr);
+	return TCL_OK;
+    } else if (objc == consumedObjc+1) {
+	if (Tcl_GetIndexFromObj(interp, objv[consumedObjc], options, "option",
+		0, &index) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	switch ((enum Options) index) {
+	case OPT_CMD:
+	    key.interp = slaveInterp;
+	    key.type = TCL_LIMIT_TIME;
+	    hPtr = Tcl_FindHashEntry(&iPtr->limit.callbacks, (char *) &key);
+	    if (hPtr != NULL) {
+		limitCBPtr = Tcl_GetHashValue(hPtr);
+		if (limitCBPtr != NULL && limitCBPtr->scriptObj != NULL) {
+		    Tcl_SetObjResult(interp, limitCBPtr->scriptObj);
+		}
+	    }
+	    break;
+	case OPT_GRAN:
+	    Tcl_SetObjResult(interp, Tcl_NewIntObj(
+		    Tcl_LimitGetGranularity(slaveInterp, TCL_LIMIT_TIME)));
+	    break;
+	case OPT_MILLI:
+	    if (Tcl_LimitTypeEnabled(slaveInterp, TCL_LIMIT_TIME)) {
+		Tcl_Time limitMoment;
+
+		Tcl_LimitGetTime(slaveInterp, &limitMoment);
+		Tcl_SetObjResult(interp,
+			Tcl_NewLongObj(limitMoment.usec/1000));
+	    }
+	    break;
+	case OPT_SEC:
+	    if (Tcl_LimitTypeEnabled(slaveInterp, TCL_LIMIT_TIME)) {
+		Tcl_Time limitMoment;
+
+		Tcl_LimitGetTime(slaveInterp, &limitMoment);
+		Tcl_SetObjResult(interp, Tcl_NewLongObj(limitMoment.sec));
+	    }
+	    break;
+	}
+	return TCL_OK;
+    } else if ((objc-consumedObjc) & 1 /* isOdd(objc-consumedObjc) */) {
+	Tcl_WrongNumArgs(interp, consumedObjc, objv, "?-option value ...?");
+	return TCL_ERROR;
+    } else {
+	int i, scriptLen = 0, milliLen = 0, secLen = 0;
+	Tcl_Obj *scriptObj = NULL, *granObj = NULL;
+	Tcl_Obj *milliObj = NULL, *secObj = NULL;
+	int gran = 0;
+	Tcl_Time limitMoment;
+	int tmp;
+
+	Tcl_LimitGetTime(slaveInterp, &limitMoment);
+	for (i=consumedObjc ; i<objc ; i+=2) {
+	    if (Tcl_GetIndexFromObj(interp, objv[i], options, "option", 0,
+		    &index) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    switch ((enum Options) index) {
+	    case OPT_CMD:
+		scriptObj = objv[i+1];
+		(void) Tcl_GetStringFromObj(objv[i+1], &scriptLen);
+		break;
+	    case OPT_GRAN:
+		granObj = objv[i+1];
+		if (TclGetIntFromObj(interp, objv[i+1], &gran) != TCL_OK) {
+		    return TCL_ERROR;
+		}
+		if (gran < 1) {
+		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			    "granularity must be at least 1", -1));
+		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+			    "BADVALUE", NULL);
+		    return TCL_ERROR;
+		}
+		break;
+	    case OPT_MILLI:
+		milliObj = objv[i+1];
+		(void) Tcl_GetStringFromObj(objv[i+1], &milliLen);
+		if (milliLen == 0) {
+		    break;
+		}
+		if (TclGetIntFromObj(interp, objv[i+1], &tmp) != TCL_OK) {
+		    return TCL_ERROR;
+		}
+		if (tmp < 0) {
+		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			    "milliseconds must be at least 0", -1));
+		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+			    "BADVALUE", NULL);
+		    return TCL_ERROR;
+		}
+		limitMoment.usec = ((long) tmp)*1000;
+		break;
+	    case OPT_SEC:
+		secObj = objv[i+1];
+		(void) Tcl_GetStringFromObj(objv[i+1], &secLen);
+		if (secLen == 0) {
+		    break;
+		}
+		if (TclGetIntFromObj(interp, objv[i+1], &tmp) != TCL_OK) {
+		    return TCL_ERROR;
+		}
+		if (tmp < 0) {
+		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			    "seconds must be at least 0", -1));
+		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+			    "BADVALUE", NULL);
+		    return TCL_ERROR;
+		}
+		limitMoment.sec = tmp;
+		break;
+	    }
+	}
+	if (milliObj != NULL || secObj != NULL) {
+	    if (milliObj != NULL) {
+		/*
+		 * Setting -milliseconds but clearing -seconds, or resetting
+		 * -milliseconds but not resetting -seconds? Bad voodoo!
+		 */
+
+		if (secObj != NULL && secLen == 0 && milliLen > 0) {
+		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			    "may only set -milliseconds if -seconds is not "
+			    "also being reset", -1));
+		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+			    "BADUSAGE", NULL);
+		    return TCL_ERROR;
+		}
+		if (milliLen == 0 && (secObj == NULL || secLen > 0)) {
+		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			    "may only reset -milliseconds if -seconds is "
+			    "also being reset", -1));
+		    Tcl_SetErrorCode(interp, "TCL", "OPERATION", "INTERP",
+			    "BADUSAGE", NULL);
+		    return TCL_ERROR;
+		}
+	    }
+
+	    if (milliLen > 0 || secLen > 0) {
+		/*
+		 * Force usec to be in range [0..1000000), possibly
+		 * incrementing sec in the process. This makes it much easier
+		 * for people to write scripts that do small time increments.
+		 */
+
+		limitMoment.sec += limitMoment.usec / 1000000;
+		limitMoment.usec %= 1000000;
+
+		Tcl_LimitSetTime(slaveInterp, &limitMoment);
+		Tcl_LimitTypeSet(slaveInterp, TCL_LIMIT_TIME);
+	    } else {
+		Tcl_LimitTypeReset(slaveInterp, TCL_LIMIT_TIME);
+	    }
+	}
+	if (scriptObj != NULL) {
+	    SetScriptLimitCallback(interp, TCL_LIMIT_TIME, slaveInterp,
+		    (scriptLen > 0 ? scriptObj : NULL));
+	}
+	if (granObj != NULL) {
+	    Tcl_LimitSetGranularity(slaveInterp, TCL_LIMIT_TIME, gran);
+	}
+	return TCL_OK;
+    }
+}
+
+/*
+ * Local Variables:
+ * mode: c
+ * c-basic-offset: 4
+ * fill-column: 78
+ * End:
+ */