# safe.tcl --
#
# This file provide a safe loading/sourcing mechanism for safe interpreters.
# It implements a virtual path mecanism to hide the real pathnames from the
# slave. It runs in a master interpreter and sets up data structure and
# aliases that will be invoked when used from a slave interpreter.
# 
# See the safe.n man page for details.
#
# Copyright (c) 1996-1997 Sun Microsystems, Inc.
#
# See the file "license.terms" for information on usage and redistribution of
# this file, and for a DISCLAIMER OF ALL WARRANTIES.
#
# RCS: @(#) $Id: safe.tcl,v 1.20 2009/11/05 19:07:35 andreas_kupries Exp $

#
# The implementation is based on namespaces. These naming conventions are
# followed:
# Private procs starts with uppercase.
# Public  procs are exported and starts with lowercase
#

# Needed utilities package
package require opt 0.4.1

# Create the safe namespace
namespace eval ::safe {

    # Exported API:
    namespace export interpCreate interpInit interpConfigure interpDelete \
	    interpAddToAccessPath interpFindInAccessPath setLogCmd

    ####
    #
    # Setup the arguments parsing
    #
    ####

    # Make sure that our temporary variable is local to this namespace.  [Bug
    # 981733]
    variable temp

    # Share the descriptions
    set temp [::tcl::OptKeyRegister {
	{-accessPath -list {} "access path for the slave"}
	{-noStatics "prevent loading of statically linked pkgs"}
	{-statics true "loading of statically linked pkgs"}
	{-nestedLoadOk "allow nested loading"}
	{-nested false "nested loading"}
	{-deleteHook -script {} "delete hook"}
    }]

    # create case (slave is optional)
    ::tcl::OptKeyRegister {
	{?slave? -name {} "name of the slave (optional)"}
    } ::safe::interpCreate
    # adding the flags sub programs to the command program (relying on Opt's
    # internal implementation details)
    lappend ::tcl::OptDesc(::safe::interpCreate) $::tcl::OptDesc($temp)

    # init and configure (slave is needed)
    ::tcl::OptKeyRegister {
	{slave -name {} "name of the slave"}
    } ::safe::interpIC
    # adding the flags sub programs to the command program (relying on Opt's
    # internal implementation details)
    lappend ::tcl::OptDesc(::safe::interpIC) $::tcl::OptDesc($temp)
    # temp not needed anymore
    ::tcl::OptKeyDelete $temp

    # Helper function to resolve the dual way of specifying staticsok (either
    # by -noStatics or -statics 0)
    proc ::safe::InterpStatics {} {
	foreach v {Args statics noStatics} {
	    upvar $v $v
	}
	set flag [::tcl::OptProcArgGiven -noStatics]
	if {$flag && (!$noStatics == !$statics) 
	          && ([::tcl::OptProcArgGiven -statics])} {
	    return -code error\
		    "conflicting values given for -statics and -noStatics"
	}
	if {$flag} {
	    return [expr {!$noStatics}]
	} else {
	    return $statics
	}
    }

    # Helper function to resolve the dual way of specifying nested loading
    # (either by -nestedLoadOk or -nested 1)
    proc ::safe::InterpNested {} {
	foreach v {Args nested nestedLoadOk} {
	    upvar $v $v
	}
	set flag [::tcl::OptProcArgGiven -nestedLoadOk]
	# note that the test here is the opposite of the "InterpStatics" one
	# (it is not -noNested... because of the wanted default value)
	if {$flag && (!$nestedLoadOk != !$nested) 
	          && ([::tcl::OptProcArgGiven -nested])} {
	    return -code error\
		    "conflicting values given for -nested and -nestedLoadOk"
	}
	if {$flag} {
	    # another difference with "InterpStatics"
	    return $nestedLoadOk
	} else {
	    return $nested
	}
    }

    ####
    #
    #  API entry points that needs argument parsing :
    #
    ####

    # Interface/entry point function and front end for "Create"
    proc ::safe::interpCreate {args} {
	set Args [::tcl::OptKeyParse ::safe::interpCreate $args]
	InterpCreate $slave $accessPath \
		[InterpStatics] [InterpNested] $deleteHook
    }

    proc ::safe::interpInit {args} {
	set Args [::tcl::OptKeyParse ::safe::interpIC $args]
	if {![::interp exists $slave]} {
	    return -code error "\"$slave\" is not an interpreter"
	}
	InterpInit $slave $accessPath \
		[InterpStatics] [InterpNested] $deleteHook
    }

    proc ::safe::CheckInterp {slave} {
	if {![IsInterp $slave]} {
	    return -code error \
		    "\"$slave\" is not an interpreter managed by ::safe::"
	}
    }

    # Interface/entry point function and front end for "Configure".  This code
    # is awfully pedestrian because it would need more coupling and support
    # between the way we store the configuration values in safe::interp's and
    # the Opt package. Obviously we would like an OptConfigure to avoid
    # duplicating all this code everywhere.
    # -> TODO (the app should share or access easily the program/value stored
    # by opt)

    # This is even more complicated by the boolean flags with no values that
    # we had the bad idea to support for the sake of user simplicity in
    # create/init but which makes life hard in configure...
    # So this will be hopefully written and some integrated with opt1.0
    # (hopefully for tcl8.1 ?)
    proc ::safe::interpConfigure {args} {
	switch [llength $args] {
	    1 {
		# If we have exactly 1 argument the semantic is to return all
		# the current configuration. We still call OptKeyParse though
		# we know that "slave" is our given argument because it also
		# checks for the "-help" option.
		set Args [::tcl::OptKeyParse ::safe::interpIC $args]
		CheckInterp $slave
		set res {}
		lappend res [list -accessPath [Set [PathListName $slave]]]
		lappend res [list -statics    [Set [StaticsOkName $slave]]]
		lappend res [list -nested     [Set [NestedOkName $slave]]]
		lappend res [list -deleteHook [Set [DeleteHookName $slave]]]
		join $res
	    }
	    2 {
		# If we have exactly 2 arguments the semantic is a "configure
		# get"
		::tcl::Lassign $args slave arg

		# get the flag sub program (we 'know' about Opt's internal
		# representation of data)
		set desc [lindex [::tcl::OptKeyGetDesc ::safe::interpIC] 2]
		set hits [::tcl::OptHits desc $arg]
                if {$hits > 1} {
                    return -code error [::tcl::OptAmbigous $desc $arg]
                } elseif {$hits == 0} {
                    return -code error [::tcl::OptFlagUsage $desc $arg]
                }
		CheckInterp $slave
		set item [::tcl::OptCurDesc $desc]
		set name [::tcl::OptName $item]
		switch -exact -- $name {
		    -accessPath {
			return [list -accessPath [Set [PathListName $slave]]]
		    }
		    -statics {
			return [list -statics    [Set [StaticsOkName $slave]]]
		    }
		    -nested {
			return [list -nested     [Set [NestedOkName $slave]]]
		    }
		    -deleteHook {
			return [list -deleteHook [Set [DeleteHookName $slave]]]
		    }
		    -noStatics {
			# it is most probably a set in fact but we would need
			# then to jump to the set part and it is not *sure*
			# that it is a set action that the user want, so force
			# it to use the unambigous -statics ?value? instead:
			return -code error\
				"ambigous query (get or set -noStatics ?)\
				use -statics instead"
		    }
		    -nestedLoadOk {
			return -code error\
				"ambigous query (get or set -nestedLoadOk ?)\
				use -nested instead"
		    }
		    default {
			return -code error "unknown flag $name (bug)"
		    }
		}
	    }
	    default {
		# Otherwise we want to parse the arguments like init and
		# create did
		set Args [::tcl::OptKeyParse ::safe::interpIC $args]
		CheckInterp $slave

		# Get the current (and not the default) values of whatever has
		# not been given:
		if {![::tcl::OptProcArgGiven -accessPath]} {
		    set doreset 1
		    set accessPath [Set [PathListName $slave]]
		} else {
		    set doreset 0
		}
		if {
		    ![::tcl::OptProcArgGiven -statics]
		    && ![::tcl::OptProcArgGiven -noStatics]
		} then {
		    set statics    [Set [StaticsOkName $slave]]
		} else {
		    set statics    [InterpStatics]
		}
		if {
		    [::tcl::OptProcArgGiven -nested] ||
		    [::tcl::OptProcArgGiven -nestedLoadOk]
		} then {
		    set nested     [InterpNested]
		} else {
		    set nested     [Set [NestedOkName $slave]]
		}
		if {![::tcl::OptProcArgGiven -deleteHook]} {
		    set deleteHook [Set [DeleteHookName $slave]]
		}
		# we can now reconfigure :
		InterpSetConfig $slave $accessPath $statics $nested $deleteHook
		# auto_reset the slave (to completly synch the new access_path)
		if {$doreset} {
		    if {[catch {::interp eval $slave {auto_reset}} msg]} {
			Log $slave "auto_reset failed: $msg"
		    } else {
			Log $slave "successful auto_reset" NOTICE
		    }
		}
	    }
	}
    }

    ####
    #
    #  Functions that actually implements the exported APIs
    #
    ####

    #
    # safe::InterpCreate : doing the real job
    #
    # This procedure creates a safe slave and initializes it with the safe
    # base aliases.
    # NB: slave name must be simple alphanumeric string, no spaces, no (), no
    # {},...  {because the state array is stored as part of the name}
    #
    # Returns the slave name.
    #
    # Optional Arguments : 
    # + slave name : if empty, generated name will be used
    # + access_path: path list controlling where load/source can occur,
    #                if empty: the master auto_path will be used.
    # + staticsok  : flag, if 0 :no static package can be loaded (load {} Xxx)
    #                      if 1 :static packages are ok.
    # + nestedok: flag, if 0 :no loading to sub-sub interps (load xx xx sub)
    #                      if 1 : multiple levels are ok.
    
    # use the full name and no indent so auto_mkIndex can find us
    proc ::safe::InterpCreate {
	slave 
	access_path
	staticsok
	nestedok
	deletehook
    } {
	# Create the slave.
	if {$slave ne ""} {
	    ::interp create -safe $slave
	} else {
	    # empty argument: generate slave name
	    set slave [::interp create -safe]
	}
	Log $slave "Created" NOTICE

	# Initialize it. (returns slave name)
	InterpInit $slave $access_path $staticsok $nestedok $deletehook
    }

    #
    # InterpSetConfig (was setAccessPath) :
    #    Sets up slave virtual auto_path and corresponding structure within
    #    the master. Also sets the tcl_library in the slave to be the first
    #    directory in the path.
    #    NB: If you change the path after the slave has been initialized you
    #    probably need to call "auto_reset" in the slave in order that it gets
    #    the right auto_index() array values.

    proc ::safe::InterpSetConfig {slave access_path staticsok\
	    nestedok deletehook} {
	# determine and store the access path if empty
	if {$access_path eq ""} {
	    set access_path [uplevel \#0 set auto_path]
	    # Make sure that tcl_library is in auto_path and at the first
	    # position (needed by setAccessPath)
	    set where [lsearch -exact $access_path [info library]]
	    if {$where == -1} {
		# not found, add it.
		set access_path [concat [list [info library]] $access_path]
		Log $slave "tcl_library was not in auto_path,\
			added it to slave's access_path" NOTICE
	    } elseif {$where != 0} {
		# not first, move it first
		set access_path [concat [list [info library]]\
			[lreplace $access_path $where $where]]
		Log $slave "tcl_libray was not in first in auto_path,\
			moved it to front of slave's access_path" NOTICE
	    
	    }

	    # Add 1st level sub dirs (will searched by auto loading from tcl
	    # code in the slave using glob and thus fail, so we add them here
	    # so by default it works the same).
	    set access_path [AddSubDirs $access_path]
	}

	Log $slave "Setting accessPath=($access_path) staticsok=$staticsok\
		nestedok=$nestedok deletehook=($deletehook)" NOTICE

	# clear old autopath if it existed
	set nname [PathNumberName $slave]
	if {[Exists $nname]} {
	    set n [Set $nname]
	    for {set i 0} {$i<$n} {incr i} {
		Unset [PathToken $i $slave]
	    }
	}

	# build new one
	set slave_auto_path {}
	set i 0
	foreach dir $access_path {
	    Set [PathToken $i $slave] $dir
	    lappend slave_auto_path "\$[PathToken $i]"
	    incr i
	}
	# Extend the access list with the paths used to look for Tcl Modules.
	# We save the virtual form separately as well, as syncing it with the
	# slave has to be defered until the necessary commands are present for
	# setup.
	foreach dir [::tcl::tm::list] {
	    lappend access_path $dir
	    Set [PathToken $i $slave] $dir
	    lappend slave_auto_path "\$[PathToken $i]"
	    lappend slave_tm_path   "\$[PathToken $i]"
	    incr i
	}
	Set $nname $i
	Set [PathListName $slave] $access_path
	Set [VirtualPathListName $slave] $slave_auto_path
	Set [TmPathListName      $slave] $slave_tm_path

	Set [StaticsOkName $slave] $staticsok
	Set [NestedOkName $slave] $nestedok
	Set [DeleteHookName $slave] $deletehook

	SyncAccessPath $slave
    }

    #
    #
    # FindInAccessPath:
    #    Search for a real directory and returns its virtual Id (including the
    #    "$")
proc ::safe::interpFindInAccessPath {slave path} {
	set access_path [GetAccessPath $slave]
	set where [lsearch -exact $access_path $path]
	if {$where == -1} {
	    return -code error "$path not found in access path $access_path"
	}
	return "\$[PathToken $where]"
    }

    #
    # addToAccessPath:
    #    add (if needed) a real directory to access path and return its
    #    virtual token (including the "$").
proc ::safe::interpAddToAccessPath {slave path} {
	# first check if the directory is already in there
	try {
	    return [interpFindInAccessPath $slave $path]
	} on error {} {
	    # new one, add it:
	    set nname [PathNumberName $slave]
	    set n [Set $nname]
	    Set [PathToken $n $slave] $path

	    set token "\$[PathToken $n]"

	    Lappend [VirtualPathListName $slave] $token
	    Lappend [PathListName $slave] $path
	    Set $nname [expr {$n+1}]

	    SyncAccessPath $slave

	    return $token
	}
    }

    # This procedure applies the initializations to an already existing
    # interpreter. It is useful when you want to install the safe base aliases
    # into a preexisting safe interpreter.
    proc ::safe::InterpInit {
	slave 
	access_path
	staticsok
	nestedok
	deletehook
    } {
	# Configure will generate an access_path when access_path is empty.
	InterpSetConfig $slave $access_path $staticsok $nestedok $deletehook

	# These aliases let the slave load files to define new commands

	# NB we need to add [namespace current], aliases are always absolute
	# paths.
	::interp alias $slave source {} \
		[namespace current]::AliasSource $slave
	::interp alias $slave load {} \
		[namespace current]::AliasLoad $slave

	# This alias lets the slave use the encoding names, convertfrom,
	# convertto, and system, but not "encoding system <name>" to set the
	# system encoding.

	::interp alias $slave encoding {} \
		[namespace current]::AliasEncoding $slave

	# Handling Tcl Modules, we need a restricted form of Glob.
	::interp alias $slave glob {} \
		[namespace current]::AliasGlob $slave

	# This alias lets the slave have access to a subset of the 'file'
	# command functionality.

	AliasSubset $slave file \
		file  dir.* join root.* ext.* tail path.* split

	# This alias interposes on the 'exit' command and cleanly terminates
	# the slave.

	::interp alias $slave exit {} \
		[namespace current]::interpDelete $slave

	# The allowed slave variables already have been set by Tcl_MakeSafe(3)

	# Source init.tcl and tm.tcl into the slave, to get auto_load and
	# other procedures defined:

	if {[catch {::interp eval $slave {
	    source [file join $tcl_library init.tcl]
	}} msg]} then {
	    Log $slave "can't source init.tcl ($msg)"
	    error "can't source init.tcl into slave $slave ($msg)"
	}

	if {[catch {::interp eval $slave {
	    source [file join $tcl_library tm.tcl]
	}} msg]} then {
	    Log $slave "can't source tm.tcl ($msg)"
	    error "can't source tm.tcl into slave $slave ($msg)"
	}

	# Sync the paths used to search for Tcl modules. This can be done only
	# now, after tm.tcl was loaded.
	::interp eval $slave [list \
		::tcl::tm::add {*}[Set [TmPathListName $slave]] ]

	return $slave
    }

    # Add (only if needed, avoid duplicates) 1 level of sub directories to an
    # existing path list.  Also removes non directories from the returned
    # list.
    proc ::safe::AddSubDirs {pathList} {
	set res {}
	foreach dir $pathList {
	    if {[file isdirectory $dir]} {
		# check that we don't have it yet as a children of a previous
		# dir
		if {[lsearch -exact $res $dir]<0} {
		    lappend res $dir
		}
		foreach sub [glob -directory $dir -nocomplain *] {
		    if {([file isdirectory $sub]) \
			    && ([lsearch -exact $res $sub]<0) } {
			# new sub dir, add it !
	                lappend res $sub
	            }
		}
	    }
	}
	return $res
    }

    # This procedure deletes a safe slave managed by Safe Tcl and cleans up
    # associated state:

proc ::safe::interpDelete {slave} {
        Log $slave "About to delete" NOTICE

	# If the slave has a cleanup hook registered, call it.  Check the
	# existance because we might be called to delete an interp which has
	# not been registered with us at all
	set hookname [DeleteHookName $slave]
	if {[Exists $hookname]} {
	    set hook [Set $hookname]
	    if {![::tcl::Lempty $hook]} {
		# remove the hook now, otherwise if the hook calls us somehow,
		# we'll loop
		Unset $hookname
		try {
		    {*}$hook $slave
		} on error err {
		    Log $slave "Delete hook error ($err)"
		}
	    }
	}

	# Discard the global array of state associated with the slave, and
	# delete the interpreter.

	set statename [InterpStateName $slave]
	if {[Exists $statename]} {
	    Unset $statename
	}

	# if we have been called twice, the interp might have been deleted
	# already
	if {[::interp exists $slave]} {
	    ::interp delete $slave
	    Log $slave "Deleted" NOTICE
	}

	return
    }

    # Set (or get) the logging mecanism 

proc ::safe::setLogCmd {args} {
	variable Log
	if {[llength $args] == 0} {
	    return $Log
	} elseif {[llength $args] == 1} {
	    set Log [lindex $args 0]
	} else {
	    set Log $args
	}
    }

    # internal variable
    variable Log {}

    # ------------------- END OF PUBLIC METHODS ------------

    #
    # Sets the slave auto_path to the master recorded value.  Also sets
    # tcl_library to the first token of the virtual path.
    #
    proc ::safe::SyncAccessPath {slave} {
	set slave_auto_path [Set [VirtualPathListName $slave]]
	::interp eval $slave [list set auto_path $slave_auto_path]
	Log $slave "auto_path in $slave has been set to $slave_auto_path"\
		NOTICE
	::interp eval $slave [list set tcl_library [lindex $slave_auto_path 0]]
    }

    # Base name for storing all the slave states.  The array variable name for
    # slave foo is thus "Sfoo" and for sub slave {foo bar} "Sfoo bar" (spaces
    # are handled ok everywhere (or should)).  We add the S prefix to avoid
    # that a slave interp called "Log" would smash our "Log" variable.
    proc ::safe::InterpStateName {slave} {
	return "S$slave"
    }

    # Check that the given slave is "one of us"
    proc ::safe::IsInterp {slave} {
	expr {[Exists [InterpStateName $slave]] && [::interp exists $slave]}
    }

    # Returns the virtual token for directory number N.  If the slave argument
    # is given, it will return the corresponding master global variable name
    proc ::safe::PathToken {n {slave ""}} {
	if {$slave ne ""} {
	    return "[InterpStateName $slave](access_path,$n)"
	} else {
	    # We need to have a ":" in the token string so [file join] on the
	    # mac won't turn it into a relative path.
	    return "p(:$n:)"
	}
    }
    # returns the variable name of the complete path list
    proc ::safe::PathListName {slave} {
	return "[InterpStateName $slave](access_path)"
    }
    # returns the variable name of the complete path list
    proc ::safe::VirtualPathListName {slave} {
	return "[InterpStateName $slave](access_path_slave)"
    }
    # returns the variable name of the complete tm path list
    proc ::safe::TmPathListName {slave} {
	return "[InterpStateName $slave](tm_path_slave)"
    }
    # returns the variable name of the number of items
    proc ::safe::PathNumberName {slave} {
	return "[InterpStateName $slave](access_path,n)"
    }
    # returns the staticsok flag var name
    proc ::safe::StaticsOkName {slave} {
	return "[InterpStateName $slave](staticsok)"
    }
    # returns the nestedok flag var name
    proc ::safe::NestedOkName {slave} {
	return "[InterpStateName $slave](nestedok)"
    }
    # Run some code at the namespace toplevel
    proc ::safe::Toplevel {args} {
	namespace eval [namespace current] $args
    }
    # set/get values
    proc ::safe::Set {args} {
	Toplevel set {*}$args
    }
    # lappend on toplevel vars
    proc ::safe::Lappend {args} {
	Toplevel lappend {*}$args
    }
    # unset a var/token (currently just an global level eval)
    proc ::safe::Unset {args} {
	Toplevel unset {*}$args
    }
    # test existance 
    proc ::safe::Exists {varname} {
	Toplevel info exists $varname
    }
    # short cut for access path getting
    proc ::safe::GetAccessPath {slave} {
	Set [PathListName $slave]
    }
    # short cut for statics ok flag getting
    proc ::safe::StaticsOk {slave} {
	Set [StaticsOkName $slave]
    }
    # short cut for getting the multiples interps sub loading ok flag
    proc ::safe::NestedOk {slave} {
	Set [NestedOkName $slave]
    }
    # interp deletion storing hook name
    proc ::safe::DeleteHookName {slave} {
	return [InterpStateName $slave](cleanupHook)
    }

    #
    # translate virtual path into real path
    #
    proc ::safe::TranslatePath {slave path} {
	# somehow strip the namespaces 'functionality' out (the danger is that
	# we would strip valid macintosh "../" queries... :
	if {[string match "*::*" $path] || [string match "*..*" $path]} {
	    error "invalid characters in path $path"
	}
	set n [expr {[Set [PathNumberName $slave]]-1}]
	for {} {$n>=0} {incr n -1} {
	    # fill the token virtual names with their real value
	    set [PathToken $n] [Set [PathToken $n $slave]]
	}
	# replaces the token by their value
	subst -nobackslashes -nocommands $path
    }


    # Log eventually log an error; to enable error logging, set Log to {puts
    # stderr} for instance
    proc ::safe::Log {slave msg {type ERROR}} {
	variable Log
	if {[info exists Log] && [llength $Log]} {
	    {*}$Log "$type for slave $slave : $msg"
	}
    }


    # file name control (limit access to files/resources that should be a
    # valid tcl source file)
    proc ::safe::CheckFileName {slave file} {
	# This used to limit what can be sourced to ".tcl" and forbid files
	# with more than 1 dot and longer than 14 chars, but I changed that
	# for 8.4 as a safe interp has enough internal protection already to
	# allow sourcing anything. - hobbs

	if {![file exists $file]} {
	    # don't tell the file path
	    error "no such file or directory"
	}

	if {![file readable $file]} {
	    # don't tell the file path
	    error "not readable"
	}
    }

    # AliasGlob is the target of the "glob" alias in safe interpreters.

    proc ::safe::AliasGlob {slave args} {
	Log $slave "GLOB ! $args" NOTICE
	set cmd {}
	set at 0

	set dir        {}
	set virtualdir {}

	while {$at < [llength $args]} {
	    switch -glob -- [set opt [lindex $args $at]] {
		-nocomplain -
		-join       {
		    lappend cmd $opt
		    incr at
		}
		-directory  {
		    lappend cmd $opt
		    incr at
		    set virtualdir [lindex $args $at]

		    # get the real path from the virtual one.
		    try {
			set dir [TranslatePath $slave $virtualdir]
		    } on error msg {
			Log $slave $msg
			return -code error "permission denied"
		    }
		    # check that the path is in the access path of that slave
		    try {
			DirInAccessPath $slave $dir
		    } on error msg {
			Log $slave $msg
			return -code error "permission denied"
		    }
		    lappend cmd $dir
		    incr at
		}
		pkgIndex.tcl {
		    # Oops, this is globbing a subdirectory in regular package
		    # search. That is not wanted. Abort, handler does catch
		    # already (because glob was not defined before). See
		    # package.tcl, lines 484ff in tclPkgUnknown.
		    error "unknown command glob"
		}
		-* {
		    Log $slave "Safe base rejecting glob option '$opt'"
		    error      "Safe base rejecting glob option '$opt'"
		}
		default {
		    lappend cmd $opt
		    incr at
		}
	    }
	}

	Log $slave "GLOB = $cmd" NOTICE

	try {
	    ::interp invokehidden $slave glob {*}$cmd
	} on ok msg {
	    # Nothing to be done, just capture the 'msg' for later.
	} on error msg {
	    Log $slave $msg
	    return -code error "script error"
	}

	Log $slave "GLOB @ $msg" NOTICE

	# Translate path back to what the slave should see.
	set res {}
	foreach p $msg {
	    regsub -- ^$dir $p $virtualdir p
	    lappend res $p
	}

	Log $slave "GLOB @ $res" NOTICE
	return $res
    }

    # AliasSource is the target of the "source" alias in safe interpreters.

    proc ::safe::AliasSource {slave args} {
	set argc [llength $args]
	# Extended for handling of Tcl Modules to allow not only "source
	# filename", but "source -encoding E filename" as well.
	if {[lindex $args 0] eq "-encoding"} {
	    incr argc -2
	    set encoding [lrange $args 0 1]
	    set at 2
	} else {
	    set at 0
	    set encoding {}
	}
	if {$argc != 1} {
	    set msg "wrong # args: should be \"source ?-encoding E? fileName\""
	    Log $slave "$msg ($args)"
	    return -code error $msg
	}
	set file [lindex $args $at]
	
	# get the real path from the virtual one.
	try {
	    set file [TranslatePath $slave $file]
	} on error msg {
	    Log $slave $msg
	    return -code error "permission denied"
	}
	
	# check that the path is in the access path of that slave
	try {
	    FileInAccessPath $slave $file
	} on error msg {
	    Log $slave $msg
	    return -code error "permission denied"
	}

	# do the checks on the filename :
	try {
	    CheckFileName $slave $file
	} on error msg {
	    Log $slave "$file:$msg"
	    return -code error $msg
	}

	# passed all the tests , lets source it:
	if {[catch {
	    # We use catch here because we want to catch non-error/ok too
	    ::interp invokehidden $slave source {*}$encoding $file
	} msg]} then {
	    Log $slave $msg
	    return -code error "script error"
	}
	return $msg
    }

    # AliasLoad is the target of the "load" alias in safe interpreters.

    proc ::safe::AliasLoad {slave file args} {
	set argc [llength $args]
	if {$argc > 2} {
	    set msg "load error: too many arguments"
	    Log $slave "$msg ($argc) {$file $args}"
	    return -code error $msg
	}

	# package name (can be empty if file is not).
	set package [lindex $args 0]

	# Determine where to load. load use a relative interp path and {}
	# means self, so we can directly and safely use passed arg.
	set target [lindex $args 1]
	if {$target ne ""} {
	    # we will try to load into a sub sub interp; check that we want to
	    # authorize that.
	    if {![NestedOk $slave]} {
		Log $slave "loading to a sub interp (nestedok)\
			disabled (trying to load $package to $target)"
		return -code error "permission denied (nested load)"
	    }
	}

	# Determine what kind of load is requested
	if {$file eq ""} {
	    # static package loading
	    if {$package eq ""} {
		set msg "load error: empty filename and no package name"
		Log $slave $msg
		return -code error $msg
	    }
	    if {![StaticsOk $slave]} {
		Log $slave "static packages loading disabled\
			(trying to load $package to $target)"
		return -code error "permission denied (static package)"
	    }
	} else {
	    # file loading

	    # get the real path from the virtual one.
	    try {
		set file [TranslatePath $slave $file]
	    } on error msg {
		Log $slave $msg
		return -code error "permission denied"
	    }

	    # check the translated path
	    try {
		FileInAccessPath $slave $file
	    } on error msg {
		Log $slave $msg
		return -code error "permission denied (path)"
	    }
	}

	try {
	    ::interp invokehidden $slave load $file $package $target
	} on error msg {
	    Log $slave $msg
	    return -code error $msg
	}

	return $msg
    }

    # FileInAccessPath raises an error if the file is not found in the list of
    # directories contained in the (master side recorded) slave's access path.

    # the security here relies on "file dirname" answering the proper
    # result... needs checking ?
    proc ::safe::FileInAccessPath {slave file} {
	set access_path [GetAccessPath $slave]

	if {[file isdirectory $file]} {
	    error "\"$file\": is a directory"
	}
	set parent [file dirname $file]

	# Normalize paths for comparison since lsearch knows nothing of
	# potential pathname anomalies.
	set norm_parent [file normalize $parent]
	foreach path $access_path {
	    lappend norm_access_path [file normalize $path]
	}

	if {$norm_parent ni $norm_access_path} {
	    error "\"$file\": not in access_path"
	}
    }

    proc ::safe::DirInAccessPath {slave dir} {
	set access_path [GetAccessPath $slave]

	if {[file isfile $dir]} {
	    error "\"$dir\": is a file"
	}

	# Normalize paths for comparison since lsearch knows nothing of
	# potential pathname anomalies.
	set norm_dir [file normalize $dir]
	foreach path $access_path {
	    lappend norm_access_path [file normalize $path]
	}

	if {$norm_dir ni $norm_access_path} {
	    error "\"$dir\": not in access_path"
	}
    }

    # This procedure enables access from a safe interpreter to only a subset
    # of the subcommands of a command:

    proc ::safe::Subset {slave command okpat args} {
	set subcommand [lindex $args 0]
	if {[regexp $okpat $subcommand]} {
	    return [$command {*}$args]
	}
	set msg "not allowed to invoke subcommand $subcommand of $command"
	Log $slave $msg
	error $msg
    }

    # This procedure installs an alias in a slave that invokes "safesubset" in
    # the master to execute allowed subcommands. It precomputes the pattern of
    # allowed subcommands; you can use wildcards in the pattern if you wish to
    # allow subcommand abbreviation.
    #
    # Syntax is: AliasSubset slave alias target subcommand1 subcommand2...

    proc ::safe::AliasSubset {slave alias target args} {
	set pat "^("
	set sep ""
	foreach sub $args {
	    append pat $sep$sub
	    set sep |
	}
	append pat ")\$"
	::interp alias $slave $alias {}\
		[namespace current]::Subset $slave $target $pat
    }

    # AliasEncoding is the target of the "encoding" alias in safe interpreters.

    proc ::safe::AliasEncoding {slave args} {
	set argc [llength $args]

	set okpat "^(name.*|convert.*)\$"
	set subcommand [lindex $args 0]

	if {[regexp $okpat $subcommand]} {
	    return [::interp invokehidden $slave encoding {*}$args]
	}

	if {[string first $subcommand system] == 0} {
	    if {$argc == 1} {
		# passed all the tests , lets source it:
		try {
		    return [::interp invokehidden $slave encoding system]
		} on error msg {
		    Log $slave $msg
		    return -code error "script error"
		}
	    }
	    set msg "wrong # args: should be \"encoding system\""
	} else {
	    set msg "wrong # args: should be \"encoding option ?arg ...?\""
	}
	Log $slave $msg
	error $msg
    }
}