| 1 | #------------------------------------------------------------------------------
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| 2 | # File: AFCP.pm
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| 3 | #
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| 4 | # Description: Read/write AFCP trailer
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| 5 | #
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| 6 | # Revisions: 12/26/2005 - P. Harvey Created
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| 7 | #
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| 8 | # References: 1) http://www.tocarte.com/media/axs_afcp_spec.pdf
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| 9 | #------------------------------------------------------------------------------
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| 10 |
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| 11 | package Image::ExifTool::AFCP;
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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 = '1.02';
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| 18 |
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| 19 | sub ProcessAFCP($$);
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| 20 |
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| 21 | %Image::ExifTool::AFCP::Main = (
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| 22 | PROCESS_PROC => \&ProcessAFCP,
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| 23 | NOTES => q{
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| 24 | AFCP stands for AXS File Concatenation Protocol, and is a poorly designed
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| 25 | protocol for appending information to the end of files. This can be used as
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| 26 | an auxiliary technique to store IPTC information in images, but is
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| 27 | incompatible with some file formats.
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| 28 |
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| 29 | ExifTool will read and write (but not create) AFCP IPTC information in JPEG
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| 30 | images, but not other image formats.
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| 31 | },
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| 32 | IPTC => { SubDirectory => { TagTable => 'Image::ExifTool::IPTC::Main' } },
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| 33 | TEXT => 'Text',
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| 34 | Nail => {
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| 35 | Name => 'ThumbnailImage',
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| 36 | ValueConv => q{
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| 37 | my $img = substr($val, 18);
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| 38 | return $self->ValidateImage(\$img,$tag);
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| 39 | },
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| 40 | },
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| 41 | PrVw => {
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| 42 | Name => 'PreviewImage',
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| 43 | ValueConv => q{
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| 44 | my $img = substr($val, 18);
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| 45 | return $self->ValidateImage(\$img,$tag);
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| 46 | },
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| 47 | },
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| 48 | );
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| 49 |
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| 50 | #------------------------------------------------------------------------------
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| 51 | # Read/write AFCP information in a file
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| 52 | # Inputs: 0) ExifTool object reference, 1) dirInfo reference
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| 53 | # (Set 'ScanForAFCP' member in dirInfo to scan from current position for AFCP)
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| 54 | # Returns: 1 on success, 0 if this file didn't contain AFCP information
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| 55 | # -1 on write error or if the offsets were incorrect on reading
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| 56 | # - updates DataPos to point to actual AFCP start if ScanForAFCP is set
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| 57 | # - updates DirLen to trailer length
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| 58 | # - returns Fixup reference in dirInfo hash when writing
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| 59 | sub ProcessAFCP($$)
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| 60 | {
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| 61 | my ($exifTool, $dirInfo) = @_;
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| 62 | my $raf = $$dirInfo{RAF};
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| 63 | my $curPos = $raf->Tell();
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| 64 | my $offset = $$dirInfo{Offset} || 0; # offset from end of file
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| 65 | my $rtnVal = 0;
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| 66 |
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| 67 | NoAFCP: for (;;) {
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| 68 | my ($buff, $fix, $dirBuff, $valBuff, $fixup, $vers);
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| 69 | # look for AXS trailer
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| 70 | last unless $raf->Seek(-12-$offset, 2) and
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| 71 | $raf->Read($buff, 12) == 12 and
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| 72 | $buff =~ /^(AXS(!|\*))/;
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| 73 | my $endPos = $raf->Tell();
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| 74 | my $hdr = $1;
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| 75 | SetByteOrder($2 eq '!' ? 'MM' : 'II');
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| 76 | my $startPos = Get32u(\$buff, 4);
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| 77 | if ($raf->Seek($startPos, 0) and $raf->Read($buff, 12) == 12 and $buff =~ /^$hdr/) {
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| 78 | $fix = 0;
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| 79 | } else {
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| 80 | $rtnVal = -1;
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| 81 | # look for start of AXS trailer if 'ScanForAFCP'
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| 82 | last unless $$dirInfo{ScanForAFCP} and $raf->Seek($curPos, 0);
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| 83 | my $actualPos = $curPos;
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| 84 | # first look for header right at current position
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| 85 | for (;;) {
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| 86 | last if $raf->Read($buff, 12) == 12 and $buff =~ /^$hdr/;
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| 87 | last NoAFCP if $actualPos != $curPos;
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| 88 | # scan for AXS header (could be after preview image)
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| 89 | for (;;) {
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| 90 | my $buf2;
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| 91 | $raf->Read($buf2, 65536) or last NoAFCP;
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| 92 | $buff .= $buf2;
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| 93 | if ($buff =~ /$hdr/g) {
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| 94 | $actualPos += pos($buff) - length($hdr);
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| 95 | last; # ok, now go back and re-read header
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| 96 | }
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| 97 | $buf2 = substr($buf2, -3); # only need last 3 bytes for next test
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| 98 | $actualPos += length($buff) - length($buf2);
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| 99 | $buff = $buf2;
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| 100 | }
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| 101 | last unless $raf->Seek($actualPos, 0); # seek to start of AFCP
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| 102 | }
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| 103 | # calculate shift for fixing AFCP offsets
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| 104 | $fix = $actualPos - $startPos;
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| 105 | }
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| 106 | # set variables returned in dirInfo hash
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| 107 | $$dirInfo{DataPos} = $startPos + $fix; # actual start position
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| 108 | $$dirInfo{DirLen} = $endPos - ($startPos + $fix);
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| 109 |
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| 110 | $rtnVal = 1;
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| 111 | my $verbose = $exifTool->Options('Verbose');
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| 112 | my $out = $exifTool->Options('TextOut');
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| 113 | my $outfile = $$dirInfo{OutFile};
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| 114 | if ($outfile) {
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| 115 | # allow all AFCP information to be deleted
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| 116 | if ($exifTool->{DEL_GROUP}->{AFCP}) {
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| 117 | $verbose and print $out " Deleting AFCP\n";
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| 118 | ++$exifTool->{CHANGED};
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| 119 | last;
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| 120 | }
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| 121 | $dirBuff = $valBuff = '';
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| 122 | require Image::ExifTool::Fixup;
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| 123 | $fixup = $$dirInfo{Fixup};
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| 124 | $fixup or $fixup = $$dirInfo{Fixup} = new Image::ExifTool::Fixup;
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| 125 | $vers = substr($buff, 4, 2); # get version number
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| 126 | } else {
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| 127 | $exifTool->DumpTrailer($dirInfo) if $verbose or $exifTool->{HTML_DUMP};
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| 128 | }
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| 129 | # read AFCP directory data
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| 130 | my $numEntries = Get16u(\$buff, 6);
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| 131 | my $dir;
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| 132 | unless ($raf->Read($dir, 12 * $numEntries) == 12 * $numEntries) {
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| 133 | $exifTool->Error('Error reading AFCP directory', 1);
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| 134 | last;
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| 135 | }
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| 136 | if ($verbose > 2 and not $outfile) {
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| 137 | my $dat = $buff . $dir;
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| 138 | print $out " AFCP Directory:\n";
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| 139 | Image::ExifTool::HexDump(\$dat, undef,
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| 140 | Addr => $$dirInfo{DataPos},
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| 141 | Width => 12,
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| 142 | Prefix => $exifTool->{INDENT},
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| 143 | Out => $out,
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| 144 | );
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| 145 | }
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| 146 | $fix and $exifTool->Warn("Adjusted AFCP offsets by $fix", 1);
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| 147 | #
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| 148 | # process AFCP directory
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| 149 | #
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| 150 | my $tagTablePtr = GetTagTable('Image::ExifTool::AFCP::Main');
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| 151 | my ($index, $entry);
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| 152 | for ($index=0; $index<$numEntries; ++$index) {
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| 153 | my $entry = 12 * $index;
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| 154 | my $tag = substr($dir, $entry, 4);
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| 155 | my $size = Get32u(\$dir, $entry + 4);
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| 156 | my $offset = Get32u(\$dir, $entry + 8);
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| 157 | if ($size < 0x80000000 and
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| 158 | $raf->Seek($offset+$fix, 0) and
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| 159 | $raf->Read($buff, $size) == $size)
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| 160 | {
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| 161 | if ($outfile) {
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| 162 | # rewrite this information
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| 163 | my $tagInfo = $exifTool->GetTagInfo($tagTablePtr, $tag);
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| 164 | if ($tagInfo and $$tagInfo{SubDirectory}) {
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| 165 | my %subdirInfo = (
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| 166 | DataPt => \$buff,
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| 167 | DirStart => 0,
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| 168 | DirLen => $size,
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| 169 | DataPos => $offset + $fix,
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| 170 | Parent => 'AFCP',
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| 171 | );
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| 172 | my $subTable = GetTagTable($tagInfo->{SubDirectory}->{TagTable});
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| 173 | my $newDir = $exifTool->WriteDirectory(\%subdirInfo, $subTable);
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| 174 | if (defined $newDir) {
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| 175 | $size = length $newDir;
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| 176 | $buff = $newDir;
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| 177 | }
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| 178 | }
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| 179 | $fixup->AddFixup(length($dirBuff) + 8);
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| 180 | $dirBuff .= $tag . Set32u($size) . Set32u(length $valBuff);
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| 181 | $valBuff .= $buff;
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| 182 | } else {
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| 183 | # extract information
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| 184 | $exifTool->HandleTag($tagTablePtr, $tag, $buff,
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| 185 | DataPt => \$buff,
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| 186 | Size => $size,
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| 187 | Index => $index,
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| 188 | DataPos => $offset + $fix,
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| 189 | );
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| 190 | }
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| 191 | } else {
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| 192 | $exifTool->Warn("Bad AFCP directory");
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| 193 | $rtnVal = -1 if $outfile;
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| 194 | last;
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| 195 | }
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| 196 | }
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| 197 | if ($outfile and length($dirBuff)) {
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| 198 | my $outPos = Tell($outfile); # get current outfile position
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| 199 | # apply fixup to directory pointers
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| 200 | my $valPos = $outPos + 12; # start of value data
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| 201 | $fixup->{Shift} += $valPos + length($dirBuff);
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| 202 | $fixup->ApplyFixup(\$dirBuff);
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| 203 | # write the AFCP header, directory, value data and EOF record (with zero checksums)
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| 204 | Write($outfile, $hdr, $vers, Set16u(length($dirBuff)/12), Set32u(0),
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| 205 | $dirBuff, $valBuff, $hdr, Set32u($outPos), Set32u(0)) or $rtnVal = -1;
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| 206 | # complete fixup so the calling routine can apply further shifts
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| 207 | $fixup->AddFixup(length($dirBuff) + length($valBuff) + 4);
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| 208 | $fixup->{Start} += $valPos;
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| 209 | $fixup->{Shift} -= $valPos;
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| 210 | }
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| 211 | last;
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| 212 | }
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| 213 | return $rtnVal;
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| 214 | }
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| 215 |
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| 216 | 1; # end
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| 217 |
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| 218 | __END__
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| 219 |
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| 220 | =head1 NAME
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| 221 |
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| 222 | Image::ExifTool::AFCP - Read/write AFCP trailer
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| 223 |
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| 224 | =head1 SYNOPSIS
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| 225 |
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| 226 | This module is used by Image::ExifTool
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| 227 |
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| 228 | =head1 DESCRIPTION
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| 229 |
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| 230 | This module contains definitions required by Image::ExifTool to extract
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| 231 | information from the AFCP trailer. Although the AFCP specification is
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| 232 | compatible with various file formats, ExifTool currently only processes AFCP
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| 233 | in JPEG images.
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| 234 |
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| 235 | =head1 NOTES
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| 236 |
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| 237 | AFCP is a specification which allows meta information (including IPTC) to be
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| 238 | appended to the end of a file.
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| 239 |
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| 240 | It is a poorly designed protocol because (like TIFF) it uses absolute
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| 241 | offsets to specify data locations. This is a huge blunder because it makes
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| 242 | the AFCP information dependent on the file length, so it is easily
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| 243 | invalidated by image editing software which doesn't recognize the AFCP
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| 244 | trailer to fix up these offsets when the file length changes. ExifTool will
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| 245 | attempt to fix these invalid offsets if possible.
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| 246 |
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| 247 | Scanning for AFCP information may be time consuming, especially when reading
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| 248 | from a sequential device, since the information is at the end of the file.
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| 249 | In these instances, the ExifTool FastScan option may be used to disable
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| 250 | scanning for AFCP information.
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| 251 |
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| 252 | =head1 AUTHOR
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| 253 |
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| 254 | Copyright 2003-2007, Phil Harvey (phil at owl.phy.queensu.ca)
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| 255 |
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| 256 | This library is free software; you can redistribute it and/or modify it
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| 257 | under the same terms as Perl itself.
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| 258 |
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| 259 | =head1 REFERENCES
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| 260 |
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| 261 | =over 4
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| 262 |
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| 263 | =item L<http://www.tocarte.com/media/axs_afcp_spec.pdf>
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| 264 |
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| 265 | =back
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| 266 |
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| 267 | =head1 SEE ALSO
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| 268 |
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| 269 | L<Image::ExifTool::TagNames/AFCP Tags>,
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| 270 | L<Image::ExifTool(3pm)|Image::ExifTool>
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| 271 |
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| 272 | =cut
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| 273 |
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