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# Remnants of what used to be VFS init. This uses either the 8.6 core zlib
# command or the tclkit zlib package with rechan to provide a memory channel
# and a streaming decompression channel transform.
package provide vfslib 1.4
# use zlib to define zip and crc if available
if {[llength [info command zlib]] || ![catch {load "" zlib}]} {
proc vfs::zip {flag value args} {
switch -glob -- "$flag $value" {
{-mode d*} { set mode decompress }
{-mode c*} { set mode compress }
default { error "usage: zip -mode {compress|decompress} data" }
}
# kludge to allow "-nowrap 1" as second option, 5-9-2002
if {[llength $args] > 2 && [lrange $args 0 1] eq "-nowrap 1"} {
if {$mode eq "compress"} {
set mode deflate
} else {
set mode inflate
}
}
return [zlib $mode [lindex $args end]]
}
proc vfs::crc {data} {
return [zlib crc32 $data]
}
}
# Use 8.6 reflected channels or the rechan package in earlier versions to
# provide a memory channel implementation.
#
if {[info command ::chan] ne {}} {
# As the core zlib channel stacking make non-seekable channels we cannot
# implement vfs::zstream and this feature is disabled in tclkit boot.tcl
# when the command is not present (it is only used by mk4vfs)
#
#proc vfs::zstream {mode ifd clen ilen} {
# return -code error "vfs::zstream is unsupported with core zlib"
#}
proc vfs::memchan {{filename {}}} {
return [chan create {read write} \
[list [namespace origin _memchan_handler] $filename]]
}
proc vfs::_memchan_handler {filename cmd chan args} {
upvar #0 ::vfs::_memchan(buf,$chan) buf
upvar #0 ::vfs::_memchan(pos,$chan) pos
upvar #0 ::vfs::_memchan(name,$chan) name
upvar #0 ::vfs::_memchan(timer) timer
switch -exact -- $cmd {
initialize {
foreach {mode} $args break
set buf ""
set pos 0
set watch {}
set name $filename
if {![info exists timer]} { set timer "" }
return {initialize finalize watch read write seek cget cgetall}
}
finalize {
unset buf pos name
foreach event {read write} {
upvar #0 ::vfs::_memchan(watch,$event) watch
if {[info exists watch] && ([set idx [lsearch -exact $watch $chan]] >= 0)} {
set watch [lreplace $watch $idx $idx]
}
}
}
seek {
foreach {offset base} $args break
switch -exact -- $base {
current { incr offset $pos }
end { incr offset [string length $buf] }
}
if {$offset < 0} {
return -code error "error during seek on \"$chan\":\
invalid argument"
} elseif {$offset > [string length $buf]} {
set extend [expr {$offset - [string length $buf]}]
append buf [binary format @$extend]
}
return [set pos $offset]
}
read {
foreach {count} $args break
set r [string range $buf $pos [expr {$pos + $count - 1}]]
incr pos [string length $r]
return $r
}
write {
foreach {data} $args break
set count [string length $data]
if { $pos >= [string length $buf] } {
append buf $data
} else {
set last [expr { $pos + $count - 1 }]
set buf [string replace $buf $pos $last $data]
}
incr pos $count
return $count
}
cget {
foreach {option} $args break
switch -exact -- $option {
-length { return [string length $buf] }
-allocated { return [string length $buf] }
default {
return -code error "bad option \"$option\":\
should be one of -blocking, -buffering,\
-buffersize, -encoding, -eofchar, -translation,\
-length or -allocated"
}
}
}
cgetall {
return [list -length [string length $buf] \
-allocated [string length $buf]]
}
watch {
foreach {eventspec} $args break
after cancel $timer
foreach event {read write} {
upvar #0 ::vfs::_memchan(watch,$event) watch
if {![info exists watch]} { set watch {} }
set ndx [lsearch -exact $watch $chan]
if {$event in $eventspec} {
if {$ndx < 0} { lappend watch $chan }
} else {
if {$ndx >= 0} {
set watch [lreplace $watch $ndx $ndx]
}
}
}
set timer [after 10 [list ::vfs::_memchan_timer]]
}
}
}
# memchan channels are always writable and always readable
proc ::vfs::_memchan_timer {} {
set continue 0
foreach event {read write} {
upvar #0 ::vfs::_memchan(watch,$event) watch
incr continue [llength $watch]
foreach chan $watch { chan postevent $chan $event }
}
if {$continue > 0} {
set ::vfs::_memchan(timer) [after 10 [info level 0]]
}
}
} elseif {[info command rechan] ne "" || ![catch {load "" rechan}]} {
proc vfs::memchan_handler {cmd fd args} {
upvar 1 ::vfs::_memchan_buf($fd) buf
upvar 1 ::vfs::_memchan_pos($fd) pos
upvar 1 ::vfs::_memchan_nam($fd) nam
set arg1 [lindex $args 0]
switch -- $cmd {
seek {
switch [lindex $args 1] {
1 - current { incr arg1 $pos }
2 - end { incr arg1 [string length $buf]}
}
return [set pos $arg1]
}
read {
set r [string range $buf $pos [expr { $pos + $arg1 - 1 }]]
incr pos [string length $r]
return $r
}
write {
set n [string length $arg1]
if { $pos >= [string length $buf] } {
append buf $arg1
} else { # the following doesn't work yet :(
set last [expr { $pos + $n - 1 }]
set buf [string replace $buf $pos $last $arg1]
error "vfs memchan: sorry no inline write yet"
}
incr pos $n
return $n
}
close {
unset buf pos nam
}
default { error "bad cmd in memchan_handler: $cmd" }
}
}
proc vfs::memchan {{filename {}}} {
set fd [rechan ::vfs::memchan_handler 6]
set ::vfs::_memchan_buf($fd) ""
set ::vfs::_memchan_pos($fd) 0
set ::vfs::_memchan_nam($fd) $filename
return $fd
}
}
if {[info command rechan] ne "" || ![catch {load "" rechan}]} {
proc vfs::zstream_handler {zcmd ifd clen ilen imode cmd fd {a1 ""} {a2 ""}} {
#puts stderr "z $zcmd $ifd $ilen $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} {
if {[$zcmd fill] == 0} {
set c [expr {$clen - [tell $ifd]}]
if {$c > 4096} { set c 4096 }
set data [read $ifd $c]
#puts "filled $c [string length $data]"
$zcmd fill $data
}
set data [$zcmd drain $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: $cmd" }
}
}
variable ::vfs::zseq 0 ;# used to generate temp zstream cmd names
# vfs::zstream --
#
# Create a read-only seekable compressed channel using rechan and
# the streaming mode of tclkit's zlib extension.
#
# mode - compress or decompress
# ifd - input channel (should be binary)
# clen - size of compressed data in bytes
# ilen - size of decompressed data in bytes
#
proc vfs::zstream {mode ifd clen ilen} {
set cname _zstream_[incr ::vfs::zseq]
zlib s$mode $cname
fconfigure $ifd -translation binary
set cmd [list ::vfs::zstream_handler $cname $ifd $clen $ilen s$mode]
set fd [rechan $cmd 2]
set ::vfs::_zstream_pos($fd) 0
return $fd
}
}
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