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[perl5.git] / ext / MIME / Base64 / Base64.pm
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1#
2# $Id: Base64.pm,v 2.16 2001/02/24 06:28:10 gisle Exp $
3
4package MIME::Base64;
5
6=head1 NAME
7
8MIME::Base64 - Encoding and decoding of base64 strings
9
10=head1 SYNOPSIS
11
12 use MIME::Base64;
13
14 $encoded = encode_base64('Aladdin:open sesame');
15 $decoded = decode_base64($encoded);
16
17=head1 DESCRIPTION
18
19This module provides functions to encode and decode strings into the
20Base64 encoding specified in RFC 2045 - I<MIME (Multipurpose Internet
21Mail Extensions)>. The Base64 encoding is designed to represent
22arbitrary sequences of octets in a form that need not be humanly
23readable. A 65-character subset ([A-Za-z0-9+/=]) of US-ASCII is used,
24enabling 6 bits to be represented per printable character.
25
26The following functions are provided:
27
28=over 4
29
30=item encode_base64($str, [$eol])
31
32Encode data by calling the encode_base64() function. The first
33argument is the string to encode. The second argument is the line
34ending sequence to use (it is optional and defaults to C<"\n">). The
35returned encoded string is broken into lines of no more than 76
36characters each and it will end with $eol unless it is empty. Pass an
37empty string as second argument if you do not want the encoded string
38broken into lines.
39
40=item decode_base64($str)
41
42Decode a base64 string by calling the decode_base64() function. This
43function takes a single argument which is the string to decode and
44returns the decoded data.
45
46Any character not part of the 65-character base64 subset set is
47silently ignored. Characters occuring after a '=' padding character
48are never decoded.
49
50If the length of the string to decode (after ignoring
1f98619c 51non-base64 chars) is not a multiple of 4 or padding occurs too early,
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52then a warning is generated if perl is running under C<-w>.
53
54=back
55
56If you prefer not to import these routines into your namespace you can
57call them as:
58
59 use MIME::Base64 ();
60 $encoded = MIME::Base64::encode($decoded);
61 $decoded = MIME::Base64::decode($encoded);
62
63=head1 DIAGNOSTICS
64
65The following warnings might be generated if perl is invoked with the
66C<-w> switch:
67
68=over 4
69
70=item Premature end of base64 data
71
72The number of characters to decode is not a multiple of 4. Legal
73base64 data should be padded with one or two "=" characters to make
74its length a multiple of 4. The decoded result will anyway be as if
75the padding was there.
76
77=item Premature padding of base64 data
78
79The '=' padding character occurs as the first or second character
80in a base64 quartet.
81
82=back
83
84=head1 EXAMPLES
85
86If you want to encode a large file, you should encode it in chunks
87that are a multiple of 57 bytes. This ensures that the base64 lines
88line up and that you do not end up with padding in the middle. 57
89bytes of data fills one complete base64 line (76 == 57*4/3):
90
91 use MIME::Base64 qw(encode_base64);
92
93 open(FILE, "/var/log/wtmp") or die "$!";
94 while (read(FILE, $buf, 60*57)) {
95 print encode_base64($buf);
96 }
97
98or if you know you have enough memory
99
100 use MIME::Base64 qw(encode_base64);
101 local($/) = undef; # slurp
102 print encode_base64(<STDIN>);
103
104The same approach as a command line:
105
106 perl -MMIME::Base64 -0777 -ne 'print encode_base64($_)' <file
107
108Decoding does not need slurp mode if all the lines contains a multiple
109of 4 base64 chars:
110
111 perl -MMIME::Base64 -ne 'print decode_base64($_)' <file
112
113=head1 COPYRIGHT
114
115Copyright 1995-1999, 2001 Gisle Aas.
116
117This library is free software; you can redistribute it and/or
118modify it under the same terms as Perl itself.
119
120Distantly based on LWP::Base64 written by Martijn Koster
121<m.koster@nexor.co.uk> and Joerg Reichelt <j.reichelt@nexor.co.uk> and
122code posted to comp.lang.perl <3pd2lp$6gf@wsinti07.win.tue.nl> by Hans
123Mulder <hansm@wsinti07.win.tue.nl>
124
125The XS implementation use code from metamail. Copyright 1991 Bell
126Communications Research, Inc. (Bellcore)
127
128=cut
129
130use strict;
131use vars qw(@ISA @EXPORT $VERSION $OLD_CODE);
132
133require Exporter;
134require DynaLoader;
135@ISA = qw(Exporter DynaLoader);
136@EXPORT = qw(encode_base64 decode_base64);
137
a019d632 138$VERSION = '2.12';
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139
140eval { bootstrap MIME::Base64 $VERSION; };
141if ($@) {
142 # can't bootstrap XS implementation, use perl implementation
143 *encode_base64 = \&old_encode_base64;
144 *decode_base64 = \&old_decode_base64;
145
146 $OLD_CODE = $@;
147 #warn $@ if $^W;
148}
149
150# Historically this module has been implemented as pure perl code.
151# The XS implementation runs about 20 times faster, but the Perl
152# code might be more portable, so it is still here.
153
154use integer;
155
156sub old_encode_base64 ($;$)
157{
158 my $res = "";
159 my $eol = $_[1];
160 $eol = "\n" unless defined $eol;
161 pos($_[0]) = 0; # ensure start at the beginning
162
163 $res = join '', map( pack('u',$_)=~ /^.(\S*)/, ($_[0]=~/(.{1,45})/gs));
164
165 $res =~ tr|` -_|AA-Za-z0-9+/|; # `# help emacs
166 # fix padding at the end
167 my $padding = (3 - length($_[0]) % 3) % 3;
168 $res =~ s/.{$padding}$/'=' x $padding/e if $padding;
169 # break encoded string into lines of no more than 76 characters each
170 if (length $eol) {
171 $res =~ s/(.{1,76})/$1$eol/g;
172 }
173 return $res;
174}
175
176
177sub old_decode_base64 ($)
178{
179 local($^W) = 0; # unpack("u",...) gives bogus warning in 5.00[123]
180
181 my $str = shift;
182 $str =~ tr|A-Za-z0-9+=/||cd; # remove non-base64 chars
183 if (length($str) % 4) {
184 require Carp;
185 Carp::carp("Length of base64 data not a multiple of 4")
186 }
187 $str =~ s/=+$//; # remove padding
188 $str =~ tr|A-Za-z0-9+/| -_|; # convert to uuencoded format
189
190 return join'', map( unpack("u", chr(32 + length($_)*3/4) . $_),
191 $str =~ /(.{1,60})/gs);
192}
193
194# Set up aliases so that these functions also can be called as
195#
196# MIME::Base64::encode();
197# MIME::Base64::decode();
198
199*encode = \&encode_base64;
200*decode = \&decode_base64;
201
2021;