base64 decoder

 
/* ------------------------------------------------------------------ */
/* B64_2.CMD                                                          */
/*                                                                    */
/* function: base64 decoder                                           */
/*                                                                    */
/* usage: b64_2.cmd b64_file [target_extension]                       */
/*                                                                    */
/*                                                                    */
/* parameters: b64_file - name of the file to convert                 */
/*             target_extension - extension for the target file       */
/*                                (optional, def.: bin)               */
/*                                                                    */
/* history: 21.06.2003 first release                                  */
/*                                                                    */
/* notes: This code is from Yury Pogrebnyak                           */
/*        (see EMail Addresses)                                       */
/*       Parameter checking was added by Bernd Schemmer               */
/*                                                                    */
/* see also base64 encoder                                            */
/* see also Template for an installation program                      */
/* see also Base64 Converting routine                                 */
/* see also Base64 encode and decode routines                         */
/* see also UUDecoding files                                          */
/* ------------------------------------------------------------------ */

  parse arg in targetExtension

  parse source . . thisProg
  thisProg = fileSpec( 'N', thisProg )

  if in = '' then
  do
    say thisProg || ' - Error: Parameter missing!'
    say
    say 'Usage: ' || thisProg || ' binary_file_to_convert '
    say ''
    exit 1
  end /* if */

  if stream( in, "C", "QUERY EXISTS" ) = '' then
  do
    say thisProg || ' - Error: File "' || in || '" not found!'
    exit 1
  end /* if */

  if stream( in, "C", "QUERY SIZE" ) = 0 then
  do
    say thisProg || ' - Error: File "' || in || '" is empty!'
    exit 1
  end /* if */

  if targetExtension = '' then
    targetExtension = '.bin'
  else
    if right( targetExtension, 1 ) <> '.' then
      targetExtension = '.' || targetExtension

  fileLength = chars( in )
  call charin in,,fileLength

  i64 = translate( result,'0000'x,'0d0a'x )
  call stream in,'c','close'

  if length( i64 ) = 0 then
    exit /* b64_2.cmd */

  parse value filespec( 'n',in ) with out '.'
  call lastpos '\',in
  out = left( in,result ) || out'.bin'
  '@del 'out' 2>nul 1>>&2'
  d_code = xrange( '0'x,'3f'x )
  s_code = xrange( 'A','Z' ) || xrange( 'a','z' ) || '0123456789+/'
  ji = 1
  call pos '0'x,i64

  do while result \= 0

    tmp_s = ''

    if result > ji then
      tmp_s = x2b( c2x( translate( substr( i64,ji,result-ji ),d_code,s_code ) ) )

    ji = result+1

    do while tmp_s \= ''

      parse var tmp_s +2 bin.0 +6 +2 bin.1 +6 +2 bin.2 +6 +2 bin.3 +6 +2 bin.4 +6 +2 bin.5 +6  +2 bin.6 +6 +2 bin.7 +6 +2 bin.8 +6 +2 bin.9 +6 +2 bin.10 +6 +2 bin.11 +6 tmp_s
      result = bin.0 || bin.1 || bin.2 || bin.3 || bin.4 || bin.5 || bin.6 || bin.7 || bin.8 || bin.9 || bin.10 || bin.11

      if result \= '' then
        call charout out, x2c( b2x( left( result,length( result )%8*8 ) ) )

    end /* do while tmp_s \= '' */

    call pos '0'x,i64,ji

  end /* do while result \= 0 */

  call charout out
exit /* b64_2.cmd */