ADDED   tclvfs/patches/8.6/tclvfs-20080503-supportnativezlib.diff
Index: tclvfs/patches/8.6/tclvfs-20080503-supportnativezlib.diff
==================================================================
--- tclvfs/patches/8.6/tclvfs-20080503-supportnativezlib.diff
+++ tclvfs/patches/8.6/tclvfs-20080503-supportnativezlib.diff
@@ -0,0 +1,93 @@
+Binary files tclvfs-20080503.orig/library/.vfslib.tcl.swp and tclvfs-20080503-1rsk/library/.vfslib.tcl.swp differ
+diff -uNr tclvfs-20080503.orig/library/vfslib.tcl tclvfs-20080503-1rsk/library/vfslib.tcl
+--- tclvfs-20080503.orig/library/vfslib.tcl	2006-09-14 16:39:57.000000000 -0500
++++ tclvfs-20080503-1rsk/library/vfslib.tcl	2010-09-17 11:13:15.000000000 -0500
+@@ -5,6 +5,14 @@
+ 
+ namespace eval ::vfs {
+     variable zseq 0	;# used to generate temp zstream cmd names
++    variable zlibPkg 0  ;# Use Tcl 8.6+ zlib command, or zlib package
++}
++
++
++# Work with the Tcl 8.6+ built-in zlib command or the zlib package, if available
++catch {
++	package present zlib
++	set ::vfs::zlibPkg 1
+ }
+ 
+ # for backwards compatibility
+@@ -140,10 +148,70 @@
+ 	}
+     }
+ 
++    proc vfs::zstream_handler_native {zcmd ifd clen ilen imode cmd fd {a1 ""} {a2 ""}} {
++        upvar ::vfs::_zstream_pos($fd) pos
++
++        switch -- $cmd {
++            seek {
++                switch $a2 {
++                    1 - current { incr a1 $pos }
++                    2 - end { incr a1 $ilen }
++                }
++                # to seek back, rewind, i.e. start from scratch
++                if {$a1 < $pos} {
++                    rename $zcmd ""
++                    zlib $imode $zcmd
++                    seek $ifd 0
++                    set pos 0
++                }
++                # consume data while not yet at seek position
++                while {$pos < $a1} {
++                    set n [expr {$a1 - $pos}]
++                    if {$n > 4096} { set n 4096 }
++                    # 2003-02-09: read did not work (?), spell it out instead
++                    #read $fd $n
++                    zstream_handler $zcmd $ifd $clen $ilen $imode read $fd $n
++                }
++                return $pos
++            }
++            read {
++                set r ""
++                set n $a1
++                #puts stderr " want $n z $zcmd pos $pos ilen $ilen"
++                if {$n + $pos > $ilen} { set n [expr {$ilen - $pos}] }
++                while {$n > 0} {
++                    set c [expr {$clen - [tell $ifd]}]
++                    if {$c > 4096} { set c 4096 }
++                    set data [read $ifd $c]
++                    #puts "filled $c [string length $data]"
++                    $zcmd put $data
++                    set data [$zcmd get $n]
++                    #puts stderr " read [string length $data]"
++                    if {$data eq ""} break
++                    append r $data
++                    incr pos [string length $data]
++                    incr n -[string length $data]
++                }
++                return $r
++            }
++            close {
++                rename $zcmd ""
++                close $ifd
++                unset pos
++            }
++            default { error "bad cmd in zstream_handler: $cmd" }
++        }
++    }
++
+     proc vfs::zstream {mode ifd clen ilen} {
+-	set cname _zstream_[incr ::vfs::zseq]
+-	zlib s$mode $cname
+-	set cmd [list ::vfs::zstream_handler $cname $ifd $clen $ilen s$mode]
++        if {$::vfs::zlibPkg} {
++            set cname _zstream_[incr ::vfs::zseq]
++            zlib s$mode $cname
++            set cmd [list ::vfs::zstream_handler $cname $ifd $clen $ilen s$mode]
++        } else {
++            set cname [zlib stream $mode]
++            set cmd [list ::vfs::zstream_handler_native $cname $ifd $clen $ilen s$mode]
++        }
+ 	set fd [rechan $cmd 2]
+ 	set ::vfs::_zstream_pos($fd) 0
+ 	return $fd