# 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.

#
# 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
}

# 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
}

# Check that the given slave is "one of us"
proc ::safe::CheckInterp {slave} {
 namespace upvar ::safe S$slave state
 if {![info exists state] || ![::interp exists $slave]} {
	return -code error \
	 "\"$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 $slave
	 namespace upvar ::safe S$slave state

	 return [join [list \
		[list -accessPath $state(access_path)] \
		[list -statics $state(staticsok)] \
		[list -nested $state(nestedok)] \
	 [list -deleteHook $state(cleanupHook)]]]
	}
	2 {
	 # If we have exactly 2 arguments the semantic is a "configure
	 # get"
	 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 $slave
	 namespace upvar ::safe S$slave state

	 set item [::tcl::OptCurDesc $desc]
	 set name [::tcl::OptName $item]
	 switch -exact -- $name {
		-accessPath {
		 return [list -accessPath $state(access_path)]
		}
		-statics {
		 return [list -statics $state(staticsok)]
		}
		-nested {
		 return [list -nested $state(nestedok)]
		}
		-deleteHook {
		 return [list -deleteHook $state(cleanupHook)]
		}
		-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 $slave
	 namespace upvar ::safe S$slave state

	 # Get the current (and not the default) values of whatever has
	 # not been given:
	 if {![::tcl::OptProcArgGiven -accessPath]} {
		set doreset 1
		set accessPath $state(access_path)
	 } else {
		set doreset 0
	 }
	 if {
		![::tcl::OptProcArgGiven -statics]
		&& ![::tcl::OptProcArgGiven -noStatics]
	 } then {
		set statics $state(staticsok)
	 } else {
		set statics [InterpStatics]
	 }
	 if {
		[::tcl::OptProcArgGiven -nested] ||
		[::tcl::OptProcArgGiven -nestedLoadOk]
	 } then {
		set nested [InterpNested]
	 } else {
		set nested $state(nestedok)
	 }
	 if {![::tcl::OptProcArgGiven -deleteHook]} {
		set deleteHook $state(cleanupHook)
	 }
	 # 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} {
 global auto_path

 # determine and store the access path if empty
 if {$access_path eq ""} {
	set access_path $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 [linsert $access_path 0 [info library]]
	 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 [linsert \
				 [lreplace $access_path $where $where] \
				 0 [info library]]
	 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

 namespace upvar ::safe S$slave state

 # clear old autopath if it existed
 # build new one
 # 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.

 set norm_access_path {}
 set slave_access_path {}
 set map_access_path {}
 set remap_access_path {}
 set slave_tm_path {}

 set i 0
 foreach dir $access_path {
	set token [PathToken $i]
	lappend slave_access_path $token
	lappend map_access_path $token $dir
	lappend remap_access_path $dir $token
	lappend norm_access_path [file normalize $dir]
	incr i
 }

 set morepaths [::tcl::tm::list]
 while {[llength $morepaths]} {
	set addpaths $morepaths
	set morepaths {}

	foreach dir $addpaths {
	 # Prevent the addition of dirs on the tm list to the
	 # result if they are already known.
	 if {[dict exists $remap_access_path $dir]} {
		continue
	 }

	 set token [PathToken $i]
	 lappend access_path $dir
	 lappend slave_access_path $token
	 lappend map_access_path $token $dir
	 lappend remap_access_path $dir $token
	 lappend norm_access_path [file normalize $dir]
	 lappend slave_tm_path $token
	 incr i

	 # [Bug 2854929]
	 # Recursively find deeper paths which may contain
	 # modules. Required to handle modules with names like
	 # 'platform::shell', which translate into
	 # 'platform/shell-X.tm', i.e arbitrarily deep
	 # subdirectories.
	 lappend morepaths {*}[glob -nocomplain -directory $dir -type d *]
	}
 }

 set state(access_path) $access_path
 set state(access_path,map) $map_access_path
 set state(access_path,remap) $remap_access_path
 set state(access_path,norm) $norm_access_path
 set state(access_path,slave) $slave_access_path
 set state(tm_path_slave) $slave_tm_path
 set state(staticsok) $staticsok
 set state(nestedok) $nestedok
 set state(cleanupHook) $deletehook

 SyncAccessPath $slave
}

#
#
# FindInAccessPath:
# Search for a real directory and returns its virtual Id (including the
# "$")
proc ::safe::interpFindInAccessPath {slave path} {
 namespace upvar ::safe S$slave state

 if {![dict exists $state(access_path,remap) $path]} {
	return -code error "$path not found in access path $access_path"
 }

 return [dict get $state(access_path,remap) $path]
}

#
# addToAccessPath:
# add (if needed) a real directory to access path and return its
# virtual token (including the "$").
proc ::safe::interpAddToAccessPath {slave path} {
 # first check if the directory is already in there
 # (inlined interpFindInAccessPath).
 namespace upvar ::safe S$slave state

 if {[dict exists $state(access_path,remap) $path]} {
	return [dict get $state(access_path,remap) $path]
 }

 # new one, add it:
 set token [PathToken [llength $state(access_path)]]

 lappend state(access_path) $path
 lappend state(access_path,slave) $token
 lappend state(access_path,map) $token $path
 lappend state(access_path,remap) $path $token
 lappend state(access_path,norm) [file normalize $path]

 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

 # NB we need to add [namespace current], aliases are always absolute
 # paths.

 # These aliases let the slave load files to define new commands
 # This alias lets the slave use the encoding names, convertfrom,
 # convertto, and system, but not "encoding system <name>" to set the
 # system encoding.
 # Handling Tcl Modules, we need a restricted form of Glob.
 # This alias interposes on the 'exit' command and cleanly terminates
 # the slave.

 foreach {command alias} {
	source AliasSource
	load AliasLoad
	encoding AliasEncoding
	exit interpDelete
	glob AliasGlob
 } {
	::interp alias $slave $command {} [namespace current]::$alias $slave
 }

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

 ::interp expose $slave file
 foreach subcommand {dirname extension rootname tail} {
	::interp alias $slave ::tcl::file::$subcommand {} \
	 ::safe::AliasFileSubcommand $slave $subcommand
 }
 foreach subcommand {
	atime attributes copy delete executable exists isdirectory isfile
	link lstat mtime mkdir nativename normalize owned readable readlink
	rename size stat tempfile type volumes writable
 } {
	::interp alias $slave ::tcl::file::$subcommand {} \
	 ::safe::BadSubcommand $slave file $subcommand
 }

 # Subcommands of info
 foreach {subcommand alias} {
	nameofexecutable AliasExeName
 } {
	::interp alias $slave ::tcl::info::$subcommand \
	 {} [namespace current]::$alias $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 opt]} {
	Log $slave "can't source init.tcl ($msg)"
	return -options $opt "can't source init.tcl into slave $slave ($msg)"
 }

 if {[catch {::interp eval $slave {
	source [file join $tcl_library tm.tcl]
 }} msg opt]} {
	Log $slave "can't source tm.tcl ($msg)"
	return -options $opt "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.
 namespace upvar ::safe S$slave state
 if {[llength $state(tm_path_slave)] > 0} {
	::interp eval $slave [list \
		::tcl::tm::add {*}[lreverse $state(tm_path_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 $dir]} {
	 # check that we don't have it yet as a children of a previous
	 # dir
	 if {$dir ni $res} {
		lappend res $dir
	 }
	 foreach sub [glob -directory $dir -nocomplain *] {
		if {[file isdirectory $sub] && ($sub ni $res)} {
		 # 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

 namespace upvar ::safe S$slave state

 # 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

 if {[info exists state(cleanupHook)]} {
	set hook $state(cleanupHook)
	if {[llength $hook]} {
	 # remove the hook now, otherwise if the hook calls us somehow,
	 # we'll loop
	 unset state(cleanupHook)
	 try {
		{*}$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.

 if {[info exists state]} {
	unset state
 }

 # 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
 set la [llength $args]
 if {$la == 0} {
	return $Log
 } elseif {$la == 1} {
	set Log [lindex $args 0]
 } else {
	set Log $args
 }

 if {$Log eq ""} {
	# Disable logging completely. Calls to it will be compiled out
	# of all users.
	proc ::safe::Log {args} {}
 } else {
	# Activate logging, define proper command.

	proc ::safe::Log {slave msg {type ERROR}} {
	 variable Log
	 {*}$Log "$type for slave $slave : $msg"
	 return
	}
 }
}

# ------------------- 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} {
 namespace upvar ::safe S$slave state

 set slave_access_path $state(access_path,slave)
 ::interp eval $slave [list set auto_path $slave_access_path]

 Log $slave "auto_path in $slave has been set to $slave_access_path"\
	NOTICE

 # This code assumes that info library is the first element in the
 # list of auto_path's. See -> InterpSetConfig for the code which
 # ensures this condition.

 ::interp eval $slave [list \
	 set tcl_library [lindex $slave_access_path 0]]
}

# Returns the virtual token for directory number N.
proc ::safe::PathToken {n} {
 # 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:)" ;# Form tested by case 7.2
}

#
# translate virtual path into real path
#
proc ::safe::TranslatePath {slave path} {
 namespace upvar ::safe S$slave state

 # somehow strip the namespaces 'functionality' out (the danger is that
 # we would strip valid macintosh "../" queries... :
 if {[string match "*::*" $path] || [string match "*..*" $path]} {
	return -code error "invalid characters in path $path"
 }

 # Use a cached map instead of computed local vars and subst.

 return [string map $state(access_path,map) $path]
}

# 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
	return -code error "no such file or directory"
 }

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

# AliasFileSubcommand handles selected subcommands of [file] in safe
# interpreters that are *almost* safe. In particular, it just acts to
# prevent discovery of what home directories exist.

proc ::safe::AliasFileSubcommand {slave subcommand name} {
 if {[string match ~* $name]} {
	set name ./$name
 }
 tailcall ::interp invokehidden $slave tcl:file:$subcommand $name
}

# 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
 array set got {
	-directory 0
	-nocomplain 0
	-join 0
	-tails 0
	-- 0
 }

 if {$::tcl_platform(platform) eq "windows"} {
	set dirPartRE {^(.*)[\\/]([^\\/]*)$}
 } else {
	set dirPartRE {^(.*)/([^/]*)$}
 }

 set dir {}
 set virtualdir {}

 while {$at < [llength $args]} {
	switch -glob -- [set opt [lindex $args $at]] {
	 -nocomplain - -- - -join - -tails {
		lappend cmd $opt
		set got($opt) 1
		incr at
	 }
	 -types - -type {
		lappend cmd -types [lindex $args [incr at]]
		incr at
	 }
	 -directory {
		if {$got($opt)} {
		 return -code error \
			{"-directory" cannot be used with "-path"}
		}
		set got($opt) 1
		set virtualdir [lindex $args [incr at]]
		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.
		return -code error "unknown command glob"
	 }
	 -* {
		Log $slave "Safe base rejecting glob option '$opt'"
		return -code error "Safe base rejecting glob option '$opt'"
	 }
	 default {
		break
	 }
	}
	if {$got(--)} break
 }

 # Get the real path from the virtual one and check that the path is in the
 # access path of that slave. Done after basic argument processing so that
 # we know if -nocomplain is set.
 if {$got(-directory)} {
	try {
	 set dir [TranslatePath $slave $virtualdir]
	 DirInAccessPath $slave $dir
	} on error msg {
	 Log $slave $msg
	 if {$got(-nocomplain)} return
	 return -code error "permission denied"
	}
	lappend cmd -directory $dir
 }

 # Apply the -join semantics ourselves
 if {$got(-join)} {
	set args [lreplace $args $at end [join [lrange $args $at end] "/"]]
 }

 # Process remaining pattern arguments
 set firstPattern [llength $cmd]
 foreach opt [lrange $args $at end] {
	if {![regexp $dirPartRE $opt -> thedir thefile]} {
	 set thedir .
	} elseif {[string match ~* $thedir]} {
	 set thedir ./$thedir
	}
	if {$thedir eq "*" &&
		($thefile eq "pkgIndex.tcl" || $thefile eq "*.tm")} {
	 set mapped 0
	 foreach d [glob -directory [TranslatePath $slave $virtualdir] \
			 -types d -tails *] {
		catch {
		 DirInAccessPath $slave \
			[TranslatePath $slave [file join $virtualdir $d]]
		 lappend cmd [file join $d $thefile]
		 set mapped 1
		}
	 }
	 if {$mapped} continue
	}
	try {
	 DirInAccessPath $slave [TranslatePath $slave \
		 [file join $virtualdir $thedir]]
	} on error msg {
	 Log $slave $msg
	 if {$got(-nocomplain)} continue
	 return -code error "permission denied"
	}
	lappend cmd $opt
 }

 Log $slave "GLOB = $cmd" NOTICE

 if {$got(-nocomplain) && [llength $cmd] eq $firstPattern} {
	return
 }
 try {
	set entries [::interp invokehidden $slave glob {*}$cmd]
 } on error msg {
	Log $slave $msg
	return -code error "script error"
 }

 Log $slave "GLOB < $entries" NOTICE

 # Translate path back to what the slave should see.
 set res {}
 set l [string length $dir]
 foreach p $entries {
	if {[string equal -length $l $dir $p]} {
	 set p [string replace $p 0 [expr {$l-1}] $virtualdir]
	}
	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 [lindex $args 1]
	set at 2
	if {$encoding eq "identity"} {
	 Log $slave "attempt to use the identity encoding"
	 return -code error "permission denied"
	}
 } else {
	set at 0
	set encoding {}
 }
 if {$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.
 if {[catch {
	set realfile [TranslatePath $slave $file]
 } msg]} {
	Log $slave $msg
	return -code error "permission denied"
 }

 # check that the path is in the access path of that slave
 if {[catch {
	FileInAccessPath $slave $realfile
 } msg]} {
	Log $slave $msg
	return -code error "permission denied"
 }

 # do the checks on the filename :
 if {[catch {
	CheckFileName $slave $realfile
 } msg]} {
	Log $slave "$realfile:$msg"
	return -code error $msg
 }

 # Passed all the tests, lets source it. Note that we do this all manually
 # because we want to control [info script] in the slave so information
 # doesn't leak so much. [Bug 2913625]
 set old [::interp eval $slave {info script}]
 set replacementMsg "script error"
 set code [catch {
	set f [open $realfile]
	fconfigure $f -eofchar 032円
	if {$encoding ne ""} {
	 fconfigure $f -encoding $encoding
	}
	set contents [read $f]
	close $f
	::interp eval $slave [list info script $file]
 } msg opt]
 if {$code == 0} {
	set code [catch {::interp eval $slave $contents} msg opt]
	set replacementMsg $msg
 }
 catch {interp eval $slave [list info script $old]}
 # Note that all non-errors are fine result codes from [source], so we must
 # take a little care to do it properly. [Bug 2923613]
 if {$code == 1} {
	Log $slave $msg
	return -code error $replacementMsg
 }
 return -code $code -options $opt $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]

 namespace upvar ::safe S$slave state

 # 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 {!$state(nestedok)} {
	 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 $msg
	}
	if {!$state(staticsok)} {
	 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 {
	return [::interp invokehidden $slave load $file $package $target]
 } on error msg {
	Log $slave $msg
	return -code error $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} {
 namespace upvar ::safe S$slave state
 set access_path $state(access_path)

 if {[file isdirectory $file]} {
	return -code error "\"$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]

 namespace upvar ::safe S$slave state
 if {$norm_parent ni $state(access_path,norm)} {
	return -code error "\"$file\": not in access_path"
 }
}

proc ::safe::DirInAccessPath {slave dir} {
 namespace upvar ::safe S$slave state
 set access_path $state(access_path)

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

 # Normalize paths for comparison since lsearch knows nothing of
 # potential pathname anomalies.
 set norm_dir [file normalize $dir]

 namespace upvar ::safe S$slave state
 if {$norm_dir ni $state(access_path,norm)} {
	return -code error "\"$dir\": not in access_path"
 }
}

# This procedure is used to report an attempt to use an unsafe member of an
# ensemble command.

proc ::safe::BadSubcommand {slave command subcommand args} {
 set msg "not allowed to invoke subcommand $subcommand of $command"
 Log $slave $msg
 return -code error -errorcode {TCL SAFE SUBCOMMAND} $msg
}

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

proc ::safe::AliasEncoding {slave option args} {
 # Note that [encoding dirs] is not supported in safe slaves at all
 set subcommands {convertfrom convertto names system}
 try {
	set option [tcl::prefix match -error [list -level 1 -errorcode \
		[list TCL LOOKUP INDEX option $option]] $subcommands $option]
	# Special case: [encoding system] ok, but [encoding system foo] not
	if {$option eq "system" && [llength $args]} {
	 return -code error -errorcode {TCL WRONGARGS} \
		"wrong # args: should be \"encoding system\""
	}
 } on error {msg options} {
	Log $slave $msg
	return -options $options $msg
 }
 tailcall ::interp invokehidden $slave encoding $option {*}$args
}

# Various minor hiding of platform features. [Bug 2913625]

proc ::safe::AliasExeName {slave} {
 return ""
}

proc ::safe::Setup {} {
 ####
 #
 # Setup the arguments parsing
 #
 ####

 # 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

 ####
 #
 # Default: No logging.
 #
 ####

 setLogCmd {}

 # Log eventually.
 # To enable error logging, set Log to {puts stderr} for instance,
 # via setLogCmd.
 return
}

namespace eval ::safe {
 # internal variables

 # Log command, set via 'setLogCmd'. Logging is disabled when empty.
 variable Log {}

 # The package maintains a state array per slave interp under its
 # control. The name of this array is S<interp-name>. This array is
 # brought into scope where needed, using 'namespace upvar'. The S
 # prefix is used to avoid that a slave interp called "Log" smashes
 # the "Log" variable.
 #
 # The array's elements are:
 #
 # access_path : List of paths accessible to the slave.
 # access_path,norm : Ditto, in normalized form.
 # access_path,slave : Ditto, as the path tokens as seen by the slave.
 # access_path,map : dict ( token -> path )
 # access_path,remap : dict ( path -> token )
 # tm_path_slave : List of TM root directories, as tokens seen by the slave.
 # staticsok : Value of option -statics
 # nestedok : Value of option -nested
 # cleanupHook : Value of option -deleteHook
}

::safe::Setup