This procedure is defined in the server but not documented via ad_proc or proc_doc and may be intended as a private interface.
The procedure is defined as:
proc ::base64::encode {args} {
set base64_en $::base64::base64_en
# Set the default wrapchar and maximum line length to match
# the settings for MIME encoding (RFC 3548, RFC 2045). These
# are the settings used by Trf as well. Various RFCs allow for
# different wrapping characters and wraplengths, so these may
# be overridden by command line options.
set wrapchar "\n"
set maxlen 76
if { [llength $args] == 0 } {
error "wrong # args: should be \"[lindex [info level 0] 0] ?-maxlen maxlen? ?-wrapchar wrapchar? string\""
}
set optionStrings [list "-maxlen" "-wrapchar"]
for {set i 0} {$i < [llength $args] - 1} {incr i} {
set arg [lindex $args $i]
set index [lsearch -glob $optionStrings "${arg}*"]
if { $index == -1 } {
error "unknown option \"$arg\": must be -maxlen or -wrapchar"
}
incr i
if { $i >= [llength $args] - 1 } {
error "value for \"$arg\" missing"
}
set val [lindex $args $i]
# The name of the variable to assign the value to is extracted
# from the list of known options, all of which have an
# associated variable of the same name as the option without
# a leading "-". The [string range] command is used to strip
# of the leading "-" from the name of the option.
#
# FRINK: nocheck
set [string range [lindex $optionStrings $index] 1 end] $val
}
# [string is] requires Tcl8.2; this works with 8.0 too
if {[catch {expr {$maxlen % 2}}]} {
return -code error "expected integer but got \"$maxlen\""
} elseif {$maxlen < 0} {
return -code error "expected positive integer but got \"$maxlen\""
}
set string [lindex $args end]
set result {}
set state 0
set length 0
# Process the input bytes 3-by-3
binary scan $string c* X
foreach {x y z} $X {
ADD [lindex $base64_en [expr {($x >>2) & 0x3F}]]
if {$y != {}} {
ADD [lindex $base64_en [expr {(($x << 4) & 0x30) | (($y >> 4) & 0xF)}]]
if {$z != {}} {
ADD [lindex $base64_en [expr {(($y << 2) & 0x3C) | (($z >> 6) & 0x3)}]]
ADD [lindex $base64_en [expr {($z & 0x3F)}]]
} else {
set state 2
break
}
} else {
set state 1
break
}
}
if {$state == 1} {
ADD [lindex $base64_en [expr {(($x << 4) & 0x30)}]]
ADD =
ADD =
} elseif {$state == 2} {
ADD [lindex $base64_en [expr {(($y << 2) & 0x3C)}]]
ADD =
}
return $result
}
