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#------------------------------------------------------------------------------
# File: Text.pm
#
# Description: Deduce characteristics of TXT and CSV files
#
# Revisions: 2019-11-01 - P. Harvey Created
# 2020-02-13 - PH Added CSV file support
#
# References: 1) https://github.com/file/file
#------------------------------------------------------------------------------
package Image::ExifTool::Text;
use strict;
use vars qw($VERSION);
use Image::ExifTool qw(:DataAccess :Utils);
use Image::ExifTool::XMP;
$VERSION = '1.03';
# Text tags
%Image::ExifTool::Text::Main = (
VARS => { NO_ID => 1 },
GROUPS => { 0 => 'File', 1 => 'File', 2 => 'Document' },
NOTES => q{
Although basic text files contain no metadata, the following tags are
determined from a simple analysis of the data in TXT and CSV files.
Statistics are generated only for 8-bit encodings, but the L<FastScan|../ExifTool.html#FastScan> (-fast)
option may be used to limit processing to the first 64 kB in which case some
tags are not produced. To avoid long processing delays, ExifTool will issue
a minor warning and process only the first 64 kB of any file larger than 20
MB unless the L<IgnoreMinorErrors|../ExifTool.html#IgnoreMinorErrors> (-m)
option is used.
},
MIMEEncoding => { Groups => { 2 => 'Other' } },
Newlines => {
PrintConv => {
"\r\n" => 'Windows CRLF',
"\r" => 'Macintosh CR',
"\n" => 'Unix LF',
'' => '(none)',
},
},
ByteOrderMark => { PrintConv => { 0 => 'No', 1 => 'Yes' } },
LineCount => { },
WordCount => { },
Delimiter => { PrintConv => { '' => '(none)', ',' => 'Comma', ';' => 'Semicolon', "\t" => 'Tab' }},
Quoting => { PrintConv => { '' => '(none)', '"' => 'Double quotes', "'" => 'Single quotes' }},
RowCount => { },
ColumnCount => { },
);
#------------------------------------------------------------------------------
# Extract some stats from a text file
# Inputs: 0) ExifTool ref, 1) dirInfo ref
# Returns: 1 on success, 0 if this wasn't a text file
sub ProcessTXT($$)
{
my ($et, $dirInfo) = @_;
my $dataPt = $$dirInfo{TestBuff};
my $raf = $$dirInfo{RAF};
my $fast = $et->Options('FastScan') || 0;
my ($buff, $enc, $isBOM, $isUTF8);
my $nl = '';
return 0 unless length $$dataPt; # can't call it a text file if it has no text
# read more from the file if necessary
if ($fast < 3 and length($$dataPt) == $Image::ExifTool::testLen) {
$raf->Read($buff, 65536) or return 0;
$dataPt = \$buff;
}
#
# make our best guess at the character encoding (EBCDIC is not supported)
#
if ($$dataPt =~ /([\0-\x06\x0e-\x1a\x1c-\x1f\x7f])/) {
# file contains weird control characters, could be multi-byte Unicode
if ($$dataPt =~ /^(\xff\xfe\0\0|\0\0\xfe\xff)/) {
if ($1 eq "\xff\xfe\0\0") {
$enc = 'utf-32le';
$nl = $1 if $$dataPt =~ /(\r\0\0\0\n|\r|\n)\0\0\0/;
} else {
$enc = 'utf-32be';
$nl = $1 if $$dataPt =~ /\0\0\0(\r\0\0\0\n|\r|\n)/;
}
} elsif ($$dataPt =~ /^(\xff\xfe|\xfe\xff)/) {
if ($1 eq "\xff\xfe") {
$enc = 'utf-16le';
$nl = $1 if $$dataPt =~ /(\r\0\n|\r|\n)\0/;
} else {
$enc = 'utf-16be';
$nl = $1 if $$dataPt =~ /\0(\r\0\n|\r|\n)/;
}
} else {
return 0; # probably not a text file
}
$nl =~ tr/\0//d; # remove nulls from newline sequence
$isBOM = 1; # (we don't recognize UTF-16/UTF-32 without one)
} else {
$isUTF8 = Image::ExifTool::XMP::IsUTF8($dataPt, 1);
if ($isUTF8 == 0) {
$enc = 'us-ascii';
} elsif ($isUTF8 > 0) {
$enc = 'utf-8';
$isBOM = ($$dataPt =~ /^\xef\xbb\xbf/ ? 1 : 0);
} elsif ($$dataPt !~ /[\x80-\x9f]/) {
$enc = 'iso-8859-1';
} else {
$enc = 'unknown-8bit';
}
$nl = $1 if $$dataPt =~ /(\r\n|\r|\n)/;
}
my $tagTablePtr = GetTagTable('Image::ExifTool::Text::Main');
$et->SetFileType();
$et->HandleTag($tagTablePtr, MIMEEncoding => $enc);
return 1 if $fast == 3 or not $raf->Seek(0,0);
$et->HandleTag($tagTablePtr, ByteOrderMark => $isBOM) if defined $isBOM;
$et->HandleTag($tagTablePtr, Newlines => $nl);
return 1 if $fast or not defined $isUTF8;
#
# generate stats for CSV files
#
if ($$et{FileType} eq 'CSV') {
my ($delim, $quot, $ncols);
my $nrows = 0;
while ($raf->ReadLine($buff)) {
if (not defined $delim) {
my %count = ( ',' => 0, ';' => 0, "\t" => 0 );
++$count{$_} foreach $buff =~ /[,;\t]/g;
if ($count{','} > $count{';'} and $count{','} > $count{"\t"}) {
$delim = ',';
} elsif ($count{';'} > $count{"\t"}) {
$delim = ';';
} elsif ($count{"\t"}) {
$delim = "\t";
} else {
$delim = '';
$ncols = 1;
}
unless ($ncols) {
# account for delimiters in quotes (simplistically)
while ($buff =~ /(^|$delim)(["'])(.*?)\2(?=$delim|$)/sg) {
$quot = $2;
my $field = $3;
$count{$delim} -= () = $field =~ /$delim/g;
}
$ncols = $count{$delim} + 1;
}
} elsif (not $quot) {
$quot = $2 if $buff =~ /(^|$delim)(["'])(.*?)\2(?=$delim|$)/sg;
}
if (++$nrows == 1000 and $et->Warn('Not counting rows past 1000', 2)) {
undef $nrows;
last;
}
}
$et->HandleTag($tagTablePtr, Delimiter => ($delim || ''));
$et->HandleTag($tagTablePtr, Quoting => ($quot || ''));
$et->HandleTag($tagTablePtr, ColumnCount => $ncols);
$et->HandleTag($tagTablePtr, RowCount => $nrows) if $nrows;
return 1;
}
return 1 if $$et{VALUE}{FileSize} and $$et{VALUE}{FileSize} > 20000000 and
$et->Warn('Not counting lines/words in text file larger than 20 MB', 2);
#
# count lines/words and check encoding of the rest of the file
#
my ($lines, $words) = (0, 0);
my $oldNL = $/;
$/ = $nl if $nl;
while ($raf->ReadLine($buff)) {
++$lines;
++$words while $buff =~ /\S+/g;
if (not $nl and $buff =~ /(\r\n|\r|\n)$/) {
# (the first line must have been longer than 64 kB)
$$et{VALUE}{Newlines} = $nl = $1;
}
next if $raf->Tell() < 65536;
# continue to check encoding after the first 64 kB
if ($isUTF8 >= 0) { # (if ascii or utf8)
$isUTF8 = Image::ExifTool::XMP::IsUTF8(\$buff);
if ($isUTF8 > 0) {
$enc = 'utf-8';
} elsif ($isUTF8 < 0) {
$enc = $buff =~ /[\x80-\x9f]/ ? 'unknown-8bit' : 'iso-8859-1';
}
} elsif ($enc eq 'iso-8859-1' and $buff =~ /[\x80-\x9f]/) {
$enc = 'unknown-8bit';
}
}
if ($$et{VALUE}{MIMEEncoding} ne $enc) {
$$et{VALUE}{MIMEEncoding} = $enc;
$et->VPrint(0," MIMEEncoding [override] = $enc\n");
}
$/ = $oldNL;
$et->HandleTag($tagTablePtr, LineCount => $lines);
$et->HandleTag($tagTablePtr, WordCount => $words);
return 1;
}
1; # end
__END__
=head1 NAME
Image::ExifTool::Text - Read Text meta information
=head1 SYNOPSIS
This module is used by Image::ExifTool
=head1 DESCRIPTION
This module contains definitions required by Image::ExifTool to deduce some
characteristics of TXT and CSV files.
=head1 AUTHOR
Copyright 2003-2021, Phil Harvey (philharvey66 at gmail.com)
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<https://github.com/file/file>
=back
=head1 SEE ALSO
L<Image::ExifTool::TagNames/Text Tags>,
L<Image::ExifTool(3pm)|Image::ExifTool>
=cut
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