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Full Discussion: This function (decode64) runs on gawk but not on busybox awk
Top Forums Shell Programming and Scripting This function (decode64) runs on gawk but not on busybox awk Post 302939555 by Walter Misar on Thursday 26th of March 2015 04:03:02 PM
Old 03-26-2015
Busybox uses its own implementation of awk, seemingly one that uses null-terminated strings internally (as opposed to length prefixed, which could handle null characters inside strings). I used busybox 1.20.2 for my tests.

BusyBox

---------- Post updated at 09:03 PM ---------- Previous update was at 06:37 PM ----------

Converting base64 to uuencode, then uudecoding the result works with busybox and might or might not be faster than doing it all in the shell.

Code:
_decode64()
{
  [ ! -t 0 ] && set -- "${@}" $(cat)
  [ -z "${1}" ] && return 1
  printf "%s\\n" "${@}" | sed 's/=//g' | (
    echo begin 644 -
    awk 'function _decode64_awk() {
      inp = 1;
      out = "";
      while (getline) {
        for(i=1; i<=length($0); i++) {
          c = substr(uu, index(b64,substr($0,i,1)), 1);
          inp++;
          out = (out c);
          if (inp==61) {
            print "M" out;
            inp = 1;
            out = "";
          }
        }
      }      
      if (length(out)) {
        printf "%c", (32+3*length(out)/4);
        print out;
      }
    }
    BEGIN {
      b64="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
      uu="`!\"#$%&'\''()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_"
      _decode64_awk();
      exit;
    }'
    echo \`
    echo end
  ) | uudecode
}

Alternatively one could do the character translation with tr, and just do the regrouping with awk.
Last edited by Walter Misar; 03-26-2015 at 05:12 PM..
These 2 Users Gave Thanks to Walter Misar For This Post:
chilicuil vgersh99
 

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LEARN ABOUT SUSE

uuencode

uuencode(n)					       Text encoding & decoding binary data					       uuencode(n)

__________________________________________________________________________________________________________________________________________________

NAME

       uuencode - UU-encode/decode binary data

SYNOPSIS

       package require Tcl  8

       package require uuencode  ?1.1.4?

       ::uuencode::encode string

       ::uuencode::decode string

       ::uuencode::uuencode ?-name string? ?-mode octal? (-file filename | ?--? string)

       ::uuencode::uudecode (-file filename | ?--? string)

_________________________________________________________________

DESCRIPTION

       This package provides a Tcl-only implementation of the uuencode(1) and uudecode(1) commands. This encoding packs binary data into printable
       ASCII characters.

       ::uuencode::encode string
	      returns the uuencoded data. This will encode all the data passed in even if this is longer than the uuencode maximum line length. If
	      the number of input bytes is not a multiple of 3 then additional 0 bytes are added to pad the string.

       ::uuencode::decode string
	      Decodes  the  given  encoded data. This will return any padding characters as well and it is the callers responsibility to deal with
	      handling the actual length of the encoded data. (see uuencode).

       ::uuencode::uuencode ?-name string? ?-mode octal? (-file filename | ?--? string)

       ::uuencode::uudecode (-file filename | ?--? string)
	      UUDecode a file or block of data. A file may contain more than one embedded file so the result is a list where  each  element  is  a
	      three element list of filename, mode value and data.

OPTIONS

       -filename name
	      Cause the uuencode or uudecode commands to read their data from the named file rather that taking a string parameter.

       -name string
	      The  uuencoded  data header line contains the suggested file name to be used when unpacking the data. Use this option to change this
	      from the default of "data.dat".

       -mode octal
	      The uuencoded data header line contains a suggested permissions bit pattern expressed as an octal string. To change the  default	of
	      0644 you can set this option. For instance, 0755 would be suitable for an executable. See chmod(1).

EXAMPLES

       % set d [uuencode::encode "Hello World!"]
       2&5L;&\@5V]R;&0A

       % uuencode::uudecode $d
       Hello World!

       % set d [uuencode::uuencode -name hello.txt "Hello World"]
       begin 644 hello.txt
       +2&5L;&@5V]R;&0`
       `
       end

       % uuencode::uudecode $d
       {hello.txt 644 {Hello World}}

BUGS, IDEAS, FEEDBACK
       This  document,	and the package it describes, will undoubtedly contain bugs and other problems.  Please report such in the category base64
       of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883].  Please also report any ideas for enhancements you may have for
       either package and/or documentation.

KEYWORDS

       encoding, uuencode

COPYRIGHT

       Copyright (c) 2002, Pat Thoyts

base64								       1.1.4							       uuencode(n)
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