/usr/share/perl5/File/Type/Builder.pm is in libfile-type-perl 0.22-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 | package File::Type::Builder;
use strict;
use warnings;
use IO::File;
our $VERSION = "0.11";
sub new {
my $class = shift;
my $self = {};
bless $self, $class;
return $self;
}
sub parse_magic {
my $self = shift;
my $data = shift;
my $line = shift;
# storage
my $parsed = {};
my $pattern;
# offsets
$data =~ s/^([0-9a-fx]+)\s+//;
$parsed->{offset} = $1;
# pattern type
$data =~ s/(byte | short | long | string | date | beshort |
belong | bedate | leshort | lelong | ledate)(\s+)?//x;
$parsed->{pattern_type} = $1;
unless ($parsed->{pattern_type} =~ m/^(string|beshort|belong)/) {
return undef;
}
# pattern mask, if exists; buggy?
if ($data =~ m/^\&/) {
# warn "pattern mask on line $line\n";
$data =~ s/\&([a-z0-9]+)\s+//;
$parsed->{pattern_mask} = $1;
}
# handle pattern. Somewhat complex.
PARSE: while ($data =~ s/(\s*\S*\s)//) {
# add data to pattern. stop unless we've got significant whitespace.
$pattern .= $1 unless $1 =~ m/^\s+$/;
last PARSE unless ($pattern =~ m!\\\s$!);
}
# then tidy up
return undef unless defined($pattern);
$pattern =~ s/\s*$// unless $pattern =~ m/\\\s$/;
$pattern =~ s/\\(\s)/$1/g;
$pattern =~ s/\\$//g;
$parsed->{pattern} = $pattern;
# what's left is the MIME type
$data =~ s/^\s*(.*)$//;
$parsed->{mime_type} = $1;
# check there's nothing undigested
warn "On line $line, remaining '$data'. Using anyway.\n" if length($data);
# check we've got a mime type to return
if (!length($parsed->{mime_type})
|| $parsed->{mime_type} !~ m!^[^/]*/[^/]*$!) {
# warn "On line $line, no or improper MIME type: not used\n";
return undef;
}
return $parsed;
}
sub string {
my $self = shift;
my $parsed = shift;
my $escape = $self->_get_escapes();
# build a code fragment.
my $code;
my $tab = '';
if ($parsed->{offset}) {
$code = $self->_substr_handling($parsed->{offset}, 1024);
$tab = ' ';
# we have to use substr to advance to the anchor
$code .= ' if (defined $substr && $substr =~ m[^';
} else {
# can just anchor normally
$code = ' if ($data =~ m[^';
}
# manipulate regex; use File::MMagic code
my $pattern = $parsed->{pattern};
# quote metacharacters
# unless ($pattern =~ m!\\x!) {
$pattern = quotemeta($pattern);
$pattern =~ s/\\\\(.)/$escape->{$1}||$1/eg;
# }
$code .= $pattern;
# close the [] delimited regex and return mime type
$code .= ']) {';
$code .= "\n$tab return q{$parsed->{mime_type}};\n$tab }\n";
if ($tab) {
$code .= "$tab}\n";
}
return $code;
}
sub be {
my $self = shift;
my $parsed = shift;
my $length = shift;
# build both sides of the conditional
my $offset = $parsed->{offset};
my $pattern = $parsed->{pattern};
# start with substr handling
my $code = $self->_substr_handling($offset, $length);
# rhs: template
my $rhs;
if ($pattern =~ s/^0x//) {
$rhs = "pack('H*', '$pattern')";
} else {
# warn "Not sure what this magic is";
return undef;
}
# build condition
$code .= " if ($rhs eq ".'$substr ) {';
$code .= "\n return q{$parsed->{mime_type}};\n }\n }\n";
return $code;
}
sub _substr_handling {
my $self = shift;
my ($offset, $length) = @_;
my $code = ' if (length $data > '.$offset.") {\n";
$code .= ' $substr = substr($data, '.$offset.', '.$length.");\n";
return $code;
}
sub _get_escapes {
return { n => '\n',
r => '\r',
b => '\b',
t => '\t',
f => '\f',
x => '\x',
0 => '\0',
1 => '\1',
2 => '\2',
3 => '\3',
};
}
1;
__END__
=head1 NAME
File::Type::Builder - parse mime-magic and generate code
=head1 SYNOPSIS
my $build = File::Type::Builder->new();
while (<magic>) {
chomp;
my $parsed = $build->parse_magic($_);
my $code = $build->string_start($parsed);
(or string_offset or beshort)
}
=head1 DESCRIPTION
Reads in the mime-magic file format and translates it to code.
(This documentation would be longer if I really expected anyone other
than me to run the code.)
=head1 METHODS
=head2 new
Creates a new File::Type::Builder object.
=head2 parse_magic
Pulls apart a line of a mime-magic file using a string of regular
expressions.
An example mime-magic file can be found in cleancode CVS at
L<http://cleancode.org/cgi-bin/viewcvs.cgi/email/mime-magic.mime?rev=1.1.1.1>
=head2 string
Builds code to match magic that's of type string.
Has to do some cleverness to make the regular expression work properly.
=head2 be
Builds code to match 'beshort' and 'belong' magic (eg audio/mpeg,
image/jpeg).
=head1 PRIVATE METHODS
=head2 _substr_matching
Sometimes the data is smaller than the offset we're looking for in the
file. If this is the case, then the file is obviously not of that type,
and furthermore we should avoid issuing a couple of warnings that Perl
would otherwise emit.
This subroutine generates this code.
=head2 _get_escapes
Returns a reference to a hash defining characters that should not be
escaped.
=head1 TODO
=over 4
* Add handlers for other magic types (bedate, byte, etc)
* Make verbosity/logging nicer.
* Find more edge cases.
* Remove redundant 'if (length $data > 0)' check.
=back
Longer term:
=over 4
* Fix for multiple magic format types?
=back
=head1 BUGS
Incomplete. Some known issues with odd entries in mime-magic. Skips
some mime-magic lines.
=head1 SEE ALSO
L<File::Type>, which is partially generated by this module.
=head1 AUTHOR
Paul Mison <pmison@fotango.com>
=head1 COPYRIGHT
Copyright 2003 Fotango Ltd.
=head1 LICENSE
Licensed under the same terms as Perl itself.
=cut
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