/usr/share/perl5/Image/ExifTool/BigTIFF.pm is in libimage-exiftool-perl 10.80-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# File: BigTIFF.pm
#
# Description: Read Big TIFF meta information
#
# Revisions: 07/03/2007 - P. Harvey Created
#
# References: 1) http://www.awaresystems.be/imaging/tiff/bigtiff.html
#------------------------------------------------------------------------------
package Image::ExifTool::BigTIFF;
use strict;
use vars qw($VERSION);
use Image::ExifTool qw(:DataAccess :Utils);
use Image::ExifTool::Exif;
$VERSION = '1.06';
my $maxOffset = 0x7fffffff; # currently supported maximum data offset/size
#------------------------------------------------------------------------------
# Process Big IFD directory
# Inputs: 0) ExifTool object ref, 1) dirInfo ref, 2) tag table ref
# Returns: 1 on success, otherwise returns 0 and sets a Warning
sub ProcessBigIFD($$$)
{
my ($et, $dirInfo, $tagTablePtr) = @_;
my $raf = $$dirInfo{RAF};
my $verbose = $$et{OPTIONS}{Verbose};
my $htmlDump = $$et{HTML_DUMP};
my $dirName = $$dirInfo{DirName};
my $dirStart = $$dirInfo{DirStart};
$verbose = -1 if $htmlDump; # mix htmlDump into verbose so we can test for both at once
# loop through IFD chain
for (;;) {
if ($dirStart > $maxOffset and not $et->Options('LargeFileSupport')) {
$et->Warn('Huge offsets not supported (LargeFileSupport not set)');
last;
}
unless ($raf->Seek($dirStart, 0)) {
$et->Warn("Bad $dirName offset");
return 0;
}
my ($dirBuff, $index);
unless ($raf->Read($dirBuff, 8) == 8) {
$et->Warn("Truncated $dirName count");
return 0;
}
my $numEntries = Image::ExifTool::Get64u(\$dirBuff, 0);
$verbose > 0 and $et->VerboseDir($dirName, $numEntries);
my $bsize = $numEntries * 20;
if ($bsize > $maxOffset) {
$et->Warn('Huge directory counts not yet supported');
last;
}
my $bufPos = $raf->Tell();
unless ($raf->Read($dirBuff, $bsize) == $bsize) {
$et->Warn("Truncated $dirName directory");
return 0;
}
my $nextIFD;
$raf->Read($nextIFD, 8) == 8 or undef $nextIFD; # try to read next IFD pointer
if ($htmlDump) {
$et->HDump($bufPos-8, 8, "$dirName entries", "Entry count: $numEntries");
if (defined $nextIFD) {
my $tip = sprintf("Offset: 0x%.8x", Image::ExifTool::Get64u(\$nextIFD, 0));
$et->HDump($bufPos + 20 * $numEntries, 8, "Next IFD", $tip, 0);
}
}
# loop through all entries in this BigTIFF IFD
for ($index=0; $index<$numEntries; ++$index) {
my $entry = 20 * $index;
my $tagID = Get16u(\$dirBuff, $entry);
my $format = Get16u(\$dirBuff, $entry+2);
my $count = Image::ExifTool::Get64u(\$dirBuff, $entry+4);
my $formatSize = $Image::ExifTool::Exif::formatSize[$format];
unless (defined $formatSize) {
$et->HDump($bufPos+$entry,20,"[invalid IFD entry]",
"Bad format value: $format", 1);
# warn unless the IFD was just padded with zeros
$et->Warn(sprintf("Unknown format ($format) for $dirName tag 0x%x",$tagID));
return 0; # assume corrupted IFD
}
my $formatStr = $Image::ExifTool::Exif::formatName[$format];
my $size = $count * $formatSize;
my $tagInfo = $et->GetTagInfo($tagTablePtr, $tagID);
next unless defined $tagInfo or $verbose;
my $valuePtr = $entry + 12;
my ($valBuff, $valBase, $rational);
if ($size > 8) {
if ($size > $maxOffset) {
$et->Warn("Can't handle $dirName entry $index (huge size)");
next;
}
$valuePtr = Image::ExifTool::Get64u(\$dirBuff, $valuePtr);
if ($valuePtr > $maxOffset and not $et->Options('LargeFileSupport')) {
$et->Warn("Can't handle $dirName entry $index (LargeFileSupport not set)");
next;
}
unless ($raf->Seek($valuePtr, 0) and $raf->Read($valBuff, $size) == $size) {
$et->Warn("Error reading $dirName entry $index");
next;
}
$valBase = 0;
} else {
$valBuff = substr($dirBuff, $valuePtr, $size);
$valBase = $bufPos;
}
if (defined $tagInfo and not $tagInfo) {
# GetTagInfo() required the value for a Condition
$tagInfo = $et->GetTagInfo($tagTablePtr, $tagID, \$valBuff);
}
my $val = ReadValue(\$valBuff, 0, $formatStr, $count, $size, \$rational);
if ($htmlDump) {
my $tval = $val;
# show numerator/denominator separately for rational numbers
$tval .= " ($rational)" if defined $rational;
my ($tagName, $colName);
if ($tagID == 0x927c and $dirName eq 'ExifIFD') {
$tagName = 'MakerNotes';
} elsif ($tagInfo) {
$tagName = $$tagInfo{Name};
} else {
$tagName = sprintf("Tag 0x%.4x",$tagID);
}
my $dname = sprintf("$dirName-%.2d", $index);
# build our tool tip
my $tip = sprintf("Tag ID: 0x%.4x\n", $tagID) .
"Format: $formatStr\[$count]\nSize: $size bytes\n";
if ($size > 8) {
$tip .= sprintf("Value offset: 0x%.8x\n", $valuePtr);
$colName = "<span class=H>$tagName</span>";
} else {
$colName = $tagName;
}
$tval = substr($tval,0,28) . '[...]' if length($tval) > 32;
if ($formatStr =~ /^(string|undef|binary)/) {
# translate non-printable characters
$tval =~ tr/\x00-\x1f\x7f-\xff/./;
} elsif ($tagInfo and Image::ExifTool::IsInt($tval)) {
if ($$tagInfo{IsOffset}) {
$tval = sprintf('0x%.4x', $tval);
} elsif ($$tagInfo{PrintHex}) {
$tval = sprintf('0x%x', $tval);
}
}
$tip .= "Value: $tval";
$et->HDump($entry+$bufPos, 20, "$dname $colName", $tip, 1);
if ($size > 8) {
# add value data block
my $flg = ($tagInfo and $$tagInfo{SubDirectory} and $$tagInfo{MakerNotes}) ? 4 : 0;
$et->HDump($valuePtr,$size,"$tagName value",'SAME', $flg);
}
}
if ($tagInfo and $$tagInfo{SubIFD}) {
# process all SubIFD's as BigTIFF
$verbose > 0 and $et->VerboseInfo($tagID, $tagInfo,
Table => $tagTablePtr,
Index => $index,
Value => $val,
DataPt => \$valBuff,
DataPos => $valBase + $valuePtr,
Start => 0,
Size => $size,
Format => $formatStr,
Count => $count,
);
my @offsets = split ' ', $val;
my $i;
for ($i=0; $i<scalar(@offsets); ++$i) {
my $subdirName = $$tagInfo{Name};
$subdirName .= $i if $i;
my %subdirInfo = (
RAF => $raf,
DataPos => 0,
DirStart => $offsets[$i],
DirName => $subdirName,
Parent => $dirInfo,
);
$et->ProcessDirectory(\%subdirInfo, $tagTablePtr, \&ProcessBigIFD);
}
} else {
my $tagKey = $et->HandleTag($tagTablePtr, $tagID, $val,
Index => $index,
DataPt => \$valBuff,
DataPos => $valBase + $valuePtr,
Start => 0,
Size => $size,
Format => $formatStr,
TagInfo => $tagInfo,
RAF => $raf,
);
$tagKey and $et->SetGroup($tagKey, $dirName);
}
}
last unless $dirName =~ /^(IFD|SubIFD)(\d*)$/;
$dirName = $1 . (($2 || 0) + 1);
defined $nextIFD or $et->Warn("Bad $dirName pointer"), return 0;
$dirStart = Image::ExifTool::Get64u(\$nextIFD, 0);
$dirStart or last;
}
return 1;
}
#------------------------------------------------------------------------------
# Extract meta information from a BigTIFF image
# Inputs: 0) ExifTool object reference, 1) dirInfo reference
# Returns: 1 on success, 0 if this wasn't a valid BigTIFF image
sub ProcessBTF($$)
{
my ($et, $dirInfo) = @_;
my $raf = $$dirInfo{RAF};
my $buff;
return 0 unless $raf->Read($buff, 16) == 16;
return 0 unless $buff =~ /^(MM\0\x2b\0\x08\0\0|II\x2b\0\x08\0\0\0)/;
if ($$dirInfo{OutFile}) {
$et->Error('ExifTool does not support writing of BigTIFF images');
return 1;
}
$et->SetFileType('BTF'); # set the FileType tag
SetByteOrder(substr($buff, 0, 2));
my $offset = Image::ExifTool::Get64u(\$buff, 8);
if ($$et{HTML_DUMP}) {
my $o = (GetByteOrder() eq 'II') ? 'Little' : 'Big';
$et->HDump(0, 8, "BigTIFF header", "Byte order: $o endian", 0);
$et->HDump(8, 8, "IFD0 pointer", sprintf("Offset: 0x%.8x",$offset), 0);
}
my %dirInfo = (
RAF => $raf,
DataPos => 0,
DirStart => $offset,
DirName => 'IFD0',
Parent => 'BigTIFF',
);
my $tagTablePtr = GetTagTable('Image::ExifTool::Exif::Main');
$et->ProcessDirectory(\%dirInfo, $tagTablePtr, \&ProcessBigIFD);
return 1;
}
1; # end
__END__
=head1 NAME
Image::ExifTool::BigTIFF - Read Big TIFF meta information
=head1 SYNOPSIS
This module is used by Image::ExifTool
=head1 DESCRIPTION
This module contains routines required by Image::ExifTool to read meta
information in BigTIFF images.
=head1 AUTHOR
Copyright 2003-2018, Phil Harvey (phil at owl.phy.queensu.ca)
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
=head1 REFERENCES
=over 4
=item L<http://www.awaresystems.be/imaging/tiff/bigtiff.html>
=back
=head1 SEE ALSO
L<Image::ExifTool::TagNames/EXIF Tags>,
L<Image::ExifTool(3pm)|Image::ExifTool>
=cut
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