tclinterp.c

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	    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(interp, aliasName, targetInterpPtr, targetNamePtr, argcPtr,
        argvPtr)
    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;
    Tcl_HashEntry *hPtr;
    Alias *aliasPtr;
    int i, objc;
    Tcl_Obj **objv;
    
    iiPtr = (InterpInfo *) ((Interp *) interp)->interpInfo;
    hPtr = Tcl_FindHashEntry(&iiPtr->slave.aliasTable, aliasName);
    if (hPtr == NULL) {
        Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
                "alias \"", aliasName, "\" not found", (char *) NULL);
	return TCL_ERROR;
    }
    aliasPtr = (Alias *) Tcl_GetHashValue(hPtr);
    objc = aliasPtr->objc;
    objv = &aliasPtr->objPtr;

    if (targetInterpPtr != NULL) {
	*targetInterpPtr = aliasPtr->targetInterp;
    }
    if (targetNamePtr != NULL) {
	*targetNamePtr = Tcl_GetString(objv[0]);
    }
    if (argcPtr != NULL) {
	*argcPtr = objc - 1;
    }
    if (argvPtr != NULL) {
        *argvPtr = (CONST char **) 
		ckalloc((unsigned) sizeof(CONST char *) * (objc - 1));
        for (i = 1; i < objc; i++) {
            *argvPtr[i - 1] = Tcl_GetString(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(interp, aliasName, targetInterpPtr, targetNamePtr, objcPtr,
        objvPtr)
    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;
    Tcl_HashEntry *hPtr;
    Alias *aliasPtr;	
    int objc;
    Tcl_Obj **objv;

    iiPtr = (InterpInfo *) ((Interp *) interp)->interpInfo;
    hPtr = Tcl_FindHashEntry(&iiPtr->slave.aliasTable, aliasName);
    if (hPtr == (Tcl_HashEntry *) NULL) {
        Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
                "alias \"", aliasName, "\" not found", (char *) NULL);
        return TCL_ERROR;
    }
    aliasPtr = (Alias *) Tcl_GetHashValue(hPtr);
    objc = aliasPtr->objc;
    objv = &aliasPtr->objPtr;

    if (targetInterpPtr != (Tcl_Interp **) NULL) {
        *targetInterpPtr = aliasPtr->targetInterp;
    }
    if (targetNamePtr != (CONST char **) NULL) {
        *targetNamePtr = Tcl_GetString(objv[0]);
    }
    if (objcPtr != (int *) NULL) {
        *objcPtr = objc - 1;
    }
    if (objvPtr != (Tcl_Obj ***) 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(interp, cmdInterp, cmd)
    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 = (Alias *) 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_AppendStringsToObj(Tcl_GetObjResult(interp),
		    "cannot define or rename alias \"",
		    Tcl_GetString(aliasPtr->namePtr),
		    "\": interpreter deleted", (char *) NULL);
	    return TCL_ERROR;
	}
	cmdNamePtr = nextAliasPtr->objPtr;
	aliasCmd = Tcl_FindCommand(nextAliasPtr->targetInterp,
                Tcl_GetString(cmdNamePtr),
		Tcl_GetGlobalNamespace(nextAliasPtr->targetInterp),
		/*flags*/ 0);
        if (aliasCmd == (Tcl_Command) NULL) {
            return TCL_OK;
        }
	aliasCmdPtr = (Command *) aliasCmd;
        if (aliasCmdPtr == cmdPtr) {
            Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
		    "cannot define or rename alias \"",
		    Tcl_GetString(aliasPtr->namePtr),
		    "\": would create a loop", (char *) 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 = (Alias *) 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(interp, slaveInterp, masterInterp, namePtr, targetNamePtr,
	objc, objv)
    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 new, i;

    aliasPtr = (Alias *) ckalloc((unsigned) (sizeof(Alias) 
            + objc * sizeof(Tcl_Obj *)));
    aliasPtr->namePtr		= namePtr;
    Tcl_IncrRefCount(aliasPtr->namePtr);
    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);

    aliasPtr->slaveCmd = Tcl_CreateObjCommand(slaveInterp,
	    Tcl_GetString(namePtr), AliasObjCmd, (ClientData) 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->namePtr);
	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((char *) 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 delete
     * the alias command. Then retry.
     */

    slavePtr = &((InterpInfo *) ((Interp *) slaveInterp)->interpInfo)->slave;
    while (1) {
	Alias *oldAliasPtr;
	char *string;
	
	string = Tcl_GetString(namePtr);
	hPtr = Tcl_CreateHashEntry(&slavePtr->aliasTable, string, &new);
	if (new != 0) {
	    break;
	}

	oldAliasPtr = (Alias *) Tcl_GetHashValue(hPtr);
	Tcl_DeleteCommandFromToken(slaveInterp, oldAliasPtr->slaveCmd);
    }

    aliasPtr->aliasEntryPtr = hPtr;
    Tcl_SetHashValue(hPtr, (ClientData) 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 = (Target *) ckalloc((unsigned) sizeof(Target));
    targetPtr->slaveCmd = aliasPtr->slaveCmd;
    targetPtr->slaveInterp = slaveInterp;

    Tcl_MutexLock(&cntMutex);
    masterPtr = &((InterpInfo *) ((Interp *) masterInterp)->interpInfo)->master;
    do {
        hPtr = Tcl_CreateHashEntry(&masterPtr->targetTable,
                (char *) aliasCounter, &new);
	aliasCounter++;
    } while (new == 0);
    Tcl_MutexUnlock(&cntMutex);

    Tcl_SetHashValue(hPtr, (ClientData) targetPtr);
    aliasPtr->targetEntryPtr = hPtr;

    Tcl_SetObjResult(interp, namePtr);

    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(interp, slaveInterp, namePtr)
    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, Tcl_GetString(namePtr));
    if (hPtr == NULL) {
	Tcl_AppendStringsToObj(Tcl_GetObjResult(interp), "alias \"",
		Tcl_GetString(namePtr), "\" not found", NULL);
        return TCL_ERROR;
    }
    aliasPtr = (Alias *) 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(interp, slaveInterp, namePtr)
    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;