proc cgi.init {} {
  global httpFormMapHex httpFormMapChars
  set alphanumeric a-zA-Z0-9
  for {set i 1} {$i <= 256} {incr i} {
    set c [format %c $i]
    if {![string match \[$alphanumeric\] $c]} {
	set httpFormMapHex(%[format %.2x $i]) $c
	set httpFormMapHex(%[string toupper [format %.2x $i]]) $c
        set httpFormMapChars($c) %[format %.2x $i]
      }
    }
  # These are handled specially
  array set httpFormMapHex {
    + " "   %0d%0a  \n
    }
  array set httpFormMapChars {
    " " +   \n %0d%0a
    }
  }

proc cgi:stringtocgi {string} {
    global httpFormMapChars
    set alphanumeric a-zA-Z0-9
    regsub -all \[^$alphanumeric\] $string {$httpFormMapChars(&)} string
    regsub -all \n $string {\\n} string
    regsub -all \t $string {\\t} string
    regsub -all {[][{})\\]\)} $string {\\&} string
    return [subst $string]
  }

proc cgi:stringfromcgi {string} {
    global httpFormMapHex
    regsub -all {%[0-9A-Fa-f][0-9A-Fa-f]} $string {$httpFormMapHex(&)} string
    regsub -all \n $string {\\n} string
    regsub -all \t $string {\\t} string
    regsub -all {[][{})\\]\)} $string {\\&} string
    return [subst $string]
  }

proc cgi:cgi2array {string arrayvar} {
  upvar $arrayvar storearray
  foreach var [split $string &] {
    set var [split $var =]
    if ![info exists storearray([lindex $var 0])] {
      set storearray([lindex $var 0]) [cgi:stringfromcgi [lindex $var 1]]
      } {
      lappend storearray([lindex $var 0]) [cgi:stringfromcgi [lindex $var 1]]
      }
    }
  }

cgi.init