1 | #------------------------------------------------------------------------------
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2 | # File: Torrent.pm
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3 | #
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4 | # Description: Read information from BitTorrent file
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5 | #
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6 | # Revisions: 2013/08/27 - P. Harvey Created
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7 | #
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8 | # References: 1) https://wiki.theory.org/BitTorrentSpecification
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9 | #------------------------------------------------------------------------------
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10 |
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11 | package Image::ExifTool::Torrent;
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12 |
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13 | use strict;
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14 | use vars qw($VERSION);
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15 | use Image::ExifTool qw(:DataAccess :Utils);
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16 |
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17 | $VERSION = '1.04';
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18 |
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19 | sub ReadBencode($$);
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20 | sub ExtractTags($$$;$$@);
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21 |
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22 | # tags extracted from BitTorrent files
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23 | %Image::ExifTool::Torrent::Main = (
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24 | GROUPS => { 2 => 'Document' },
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25 | NOTES => q{
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26 | Below are tags commonly found in BitTorrent files. As well as these tags,
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27 | any other existing tags will be extracted. For convenience, list items are
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28 | expanded into individual tags with an index in the tag name, but only the
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29 | tags with index "1" are listed in the tables below. See
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30 | L<https://wiki.theory.org/BitTorrentSpecification> for the BitTorrent
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31 | specification.
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32 | },
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33 | 'announce' => { },
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34 | 'announce-list' => { Name => 'AnnounceList1' },
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35 | 'comment' => { },
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36 | 'created by' => { Name => 'Creator' }, # software used to create the torrent
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37 | 'creation date' => {
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38 | Name => 'CreateDate',
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39 | Groups => { 2 => 'Time' },
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40 | ValueConv => 'ConvertUnixTime($val,1)',
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41 | PrintConv => '$self->ConvertDateTime($val)',
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42 | },
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43 | 'encoding' => { },
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44 | 'info' => {
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45 | SubDirectory => { TagTable => 'Image::ExifTool::Torrent::Info' },
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46 | Notes => 'extracted as a structure with the Struct option',
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47 | },
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48 | 'url-list' => { Name => 'URLList1' },
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49 | );
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50 |
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51 | %Image::ExifTool::Torrent::Info = (
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52 | GROUPS => { 2 => 'Document' },
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53 | 'file-duration' => { Name => 'File1Duration' },
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54 | 'file-media' => { Name => 'File1Media' },
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55 | 'files' => { SubDirectory => { TagTable => 'Image::ExifTool::Torrent::Files' } },
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56 | 'length' => { },
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57 | 'md5sum' => { Name => 'MD5Sum' },
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58 | 'name' => { },
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59 | 'name.utf-8' => { Name => 'NameUTF-8' },
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60 | 'piece length' => { Name => 'PieceLength' },
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61 | 'pieces' => {
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62 | Name => 'Pieces',
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63 | Notes => 'concatenation of 20-byte SHA-1 digests for each piece',
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64 | },
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65 | 'private' => { },
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66 | 'profiles' => { SubDirectory => { TagTable => 'Image::ExifTool::Torrent::Profiles' } },
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67 | );
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68 |
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69 | %Image::ExifTool::Torrent::Profiles = (
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70 | GROUPS => { 2 => 'Document' },
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71 | 'width' => { Name => 'Profile1Width' },
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72 | 'height' => { Name => 'Profile1Height' },
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73 | 'acodec' => { Name => 'Profile1AudioCodec' },
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74 | 'vcodec' => { Name => 'Profile1VideoCodec' },
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75 | );
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76 |
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77 | %Image::ExifTool::Torrent::Files = (
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78 | GROUPS => { 2 => 'Document' },
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79 | 'length' => { Name => 'File1Length', PrintConv => 'ConvertFileSize($val)' },
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80 | 'md5sum' => { Name => 'File1MD5Sum' },
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81 | 'path' => { Name => 'File1Path', JoinPath => 1 },
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82 | 'path.utf-8' => { Name => 'File1PathUTF-8', JoinPath => 1 },
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83 | );
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84 |
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85 | #------------------------------------------------------------------------------
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86 | # Read 64kB more data into buffer
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87 | # Inputs: 0) RAF ref, 1) buffer ref
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88 | # Returns: number of bytes read
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89 | # Notes: Sets BencodeEOF element of RAF on end of file
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90 | sub ReadMore($$)
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91 | {
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92 | my ($raf, $dataPt) = @_;
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93 | my $buf2;
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94 | my $n = $raf->Read($buf2, 65536);
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95 | $$raf{BencodeEOF} = 1 if $n != 65536;
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96 | $$dataPt = substr($$dataPt, pos($$dataPt)) . $buf2 if $n;
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97 | return $n;
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98 | }
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99 |
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100 | #------------------------------------------------------------------------------
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101 | # Read bencoded value
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102 | # Inputs: 0) input file, 1) buffer (pos must be set to current position)
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103 | # Returns: HASH ref, ARRAY ref, SCALAR ref, SCALAR, or undef on error or end of data
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104 | # Notes: Sets BencodeError element of RAF on any error
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105 | sub ReadBencode($$)
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106 | {
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107 | my ($raf, $dataPt) = @_;
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108 |
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109 | # read more if necessary (keep a minimum of 64 bytes in the buffer)
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110 | my $pos = pos($$dataPt);
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111 | return undef unless defined $pos;
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112 | my $remaining = length($$dataPt) - $pos;
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113 | ReadMore($raf, $dataPt) if $remaining < 64 and not $$raf{BencodeEOF};
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114 |
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115 | # read next token
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116 | $$dataPt =~ /(.)/sg or return undef;
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117 |
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118 | my $val;
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119 | my $tok = $1;
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120 | if ($tok eq 'i') { # integer
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121 | $$dataPt =~ /\G(-?\d+)e/g or return $val;
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122 | $val = $1;
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123 | } elsif ($tok eq 'd') { # dictionary
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124 | $val = { };
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125 | for (;;) {
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126 | my $k = ReadBencode($raf, $dataPt);
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127 | last unless defined $k;
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128 | # the key must be a byte string
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129 | if (ref $k) {
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130 | ref $k ne 'SCALAR' and $$raf{BencodeError} = 'Bad dictionary key', last;
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131 | $k = $$k;
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132 | }
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133 | my $v = ReadBencode($raf, $dataPt);
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134 | last unless defined $v;
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135 | $$val{$k} = $v;
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136 | }
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137 | } elsif ($tok eq 'l') { # list
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138 | $val = [ ];
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139 | for (;;) {
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140 | my $v = ReadBencode($raf, $dataPt);
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141 | last unless defined $v;
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142 | push @$val, $v;
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143 | }
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144 | } elsif ($tok eq 'e') { # end of dictionary or list
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145 | # return undef (no error)
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146 | } elsif ($tok =~ /^\d$/ and $$dataPt =~ /\G(\d*):/g) { # byte string
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147 | my $len = $tok . $1;
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148 | my $more = $len - (length($$dataPt) - pos($$dataPt));
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149 | my $value;
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150 | if ($more <= 0) {
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151 | $value = substr($$dataPt,pos($$dataPt),$len);
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152 | pos($$dataPt) = pos($$dataPt) + $len;
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153 | } elsif ($more > 10000000) {
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154 | # just skip over really long values
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155 | $val = \ "(Binary data $len bytes)" if $raf->Seek($more, 1);
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156 | } else {
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157 | # need to read more from file
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158 | my $buff;
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159 | my $n = $raf->Read($buff, $more);
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160 | if ($n == $more) {
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161 | $value = substr($$dataPt,pos($$dataPt)) . $buff;
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162 | $$dataPt = '';
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163 | pos($$dataPt) = 0;
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164 | }
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165 | }
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166 | if (defined $value) {
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167 | # return as binary data unless it is a reasonable-length ASCII string
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168 | if (length($value) > 256 or $value =~ /[^\t\x20-\x7e]/) {
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169 | $val = \$value;
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170 | } else {
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171 | $val = $value;
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172 | }
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173 | } elsif (not defined $val) {
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174 | $$raf{BencodeError} = 'Truncated byte string';
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175 | }
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176 | } else {
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177 | $$raf{BencodeError} = 'Bad format';
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178 | }
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179 | return $val;
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180 | }
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181 |
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182 | #------------------------------------------------------------------------------
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183 | # Extract tags from dictionary hash
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184 | # Inputs: 0) ExifTool ref, 1) dictionary hash reference, 2) tag table ref,
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185 | # 3) parent hash ID, 4) parent hash name, 5-N) list indices
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186 | # Returns: number of tags extracted
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187 | sub ExtractTags($$$;$$@)
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188 | {
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189 | my ($et, $hashPtr, $tagTablePtr, $baseID, $baseName, @index) = @_;
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190 | my $count = 0;
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191 | my $tag;
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192 | foreach $tag (sort keys %$hashPtr) {
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193 | my $val = $$hashPtr{$tag};
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194 | my ($i, $j, @more);
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195 | for (; defined $val; $val = shift @more) {
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196 | my $id = defined $baseID ? "$baseID/$tag" : $tag;
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197 | unless ($$tagTablePtr{$id}) {
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198 | my $name = ucfirst $tag;
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199 | # capitalize all words in tag name and remove illegal characters
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200 | $name =~ s/[^-_a-zA-Z0-9]+(.?)/\U$1/g;
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201 | $name = "Tag$name" if length($name) < 2 or $name !~ /^[A-Z]/;
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202 | $name = $baseName . $name if defined $baseName; # add base name if necessary
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203 | AddTagToTable($tagTablePtr, $id, { Name => $name });
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204 | $et->VPrint(0, " [adding $id '${name}']\n");
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205 | }
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206 | my $tagInfo = $et->GetTagInfo($tagTablePtr, $id) or next;
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207 | if (ref $val eq 'ARRAY') {
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208 | if ($$tagInfo{JoinPath}) {
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209 | $val = join '/', @$val;
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210 | } else {
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211 | push @more, @$val;
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212 | next if ref $more[0] eq 'ARRAY'; # continue expanding nested lists
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213 | $val = shift @more;
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214 | $i or $i = 0, push(@index, $i);
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215 | }
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216 | }
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217 | $index[-1] = ++$i if defined $i;
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218 | if (@index) {
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219 | $id .= join '_', @index; # add instance number(s) to tag ID
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220 | unless ($$tagTablePtr{$id}) {
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221 | my $name = $$tagInfo{Name};
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222 | # embed indices at position of '1' in tag name
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223 | my $n = ($name =~ tr/1/#/);
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224 | for ($j=0; $j<$n; ++$j) {
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225 | my $idx = $index[$j] || '';
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226 | $name =~ s/#/$idx/;
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227 | }
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228 | # put remaining indices at end of tag name
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229 | for (; $j<@index; ++$j) {
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230 | $name .= '_' if $name =~ /\d$/;
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231 | $name .= $index[$j];
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232 | }
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233 | AddTagToTable($tagTablePtr, $id, { %$tagInfo, Name => $name });
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234 | }
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235 | $tagInfo = $et->GetTagInfo($tagTablePtr, $id) or next;
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236 | }
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237 | if (ref $val eq 'HASH') {
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238 | if ($et->Options('Struct') and $tagInfo and $$tagInfo{Name} eq 'Info') {
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239 | $et->FoundTag($tagInfo, $val);
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240 | ++$count;
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241 | next;
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242 | }
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243 | # extract tags from this dictionary
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244 | my ($table, $rootID, $rootName);
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245 | if ($$tagInfo{SubDirectory}) {
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246 | $table = GetTagTable($$tagInfo{SubDirectory}{TagTable});
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247 | } else {
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248 | $table = $tagTablePtr;
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249 | # use hash ID and Name as base for contained tags to avoid conflicts
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250 | $rootID = $id;
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251 | $rootName = $$tagInfo{Name};
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252 | }
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253 | $count += ExtractTags($et, $val, $table, $rootID, $rootName, @index);
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254 | } else {
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255 | # handle this simple tag value
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256 | $et->HandleTag($tagTablePtr, $id, $val);
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257 | ++$count;
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258 | }
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259 | }
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260 | pop @index if defined $i;
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261 | }
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262 | return $count;
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263 | }
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264 |
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265 | #------------------------------------------------------------------------------
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266 | # Process BitTorrent file
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267 | # Inputs: 0) ExifTool object reference, 1) dirInfo reference (with RAF set)
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268 | # Returns: 1 on success, 0 if this wasn't a valid BitTorrent file
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269 | sub ProcessTorrent($$)
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270 | {
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271 | my ($et, $dirInfo) = @_;
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272 | my $success = 0;
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273 | my $raf = $$dirInfo{RAF};
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274 | my $buff = '';
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275 | pos($buff) = 0;
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276 | my $dict = ReadBencode($raf, \$buff);
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277 | my $err = $$raf{BencodeError};
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278 | $et->Warn("Bencode error: $err") if $err;
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279 | if (ref $dict eq 'HASH' and ($$dict{announce} or $$dict{'created by'})) {
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280 | $et->SetFileType();
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281 | my $tagTablePtr = GetTagTable('Image::ExifTool::Torrent::Main');
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282 | ExtractTags($et, $dict, $tagTablePtr) and $success = 1;
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283 | }
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284 | return $success;
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285 | }
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286 |
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287 | 1; # end
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288 |
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289 | __END__
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290 |
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291 | =head1 NAME
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292 |
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293 | Image::ExifTool::Torrent - Read information from BitTorrent file
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294 |
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295 | =head1 SYNOPSIS
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296 |
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297 | This module is used by Image::ExifTool
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298 |
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299 | =head1 DESCRIPTION
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300 |
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301 | This module contains definitions required by Image::ExifTool to read
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302 | bencoded information from BitTorrent files.
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303 |
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304 | =head1 AUTHOR
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305 |
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306 | Copyright 2003-2021, Phil Harvey (philharvey66 at gmail.com)
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307 |
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308 | This library is free software; you can redistribute it and/or modify it
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309 | under the same terms as Perl itself.
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310 |
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311 | =head1 REFERENCES
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312 |
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313 | =over 4
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314 |
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315 | =item L<https://wiki.theory.org/BitTorrentSpecification>
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316 |
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317 | =back
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318 |
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319 | =head1 SEE ALSO
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320 |
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321 | L<Image::ExifTool::TagNames/Torrent Tags>,
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322 | L<Image::ExifTool(3pm)|Image::ExifTool>
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323 |
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324 | =cut
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325 |
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