xmlwriter: fix issue with control chartacter in data elements

lib/Excel/Writer/XLSX/Package/XMLwriter.pm

@@ -232,6 +232,7 @@ sub xml_data_element {
     }
 
     $data = _escape_data( $data );
+    $data = _escape_control_characters( $data );
 
     local $\ = undef;
     print { $self->{_fh} } "<$tag>$data</$end_tag>";
@@ -494,6 +495,29 @@ sub _escape_data {
 }
 
 
+###############################################################################
+#
+# _escape_control_characters()
+#
+# Excel escapes control characters with _xHHHH_ and also escapes any
+# literal strings of that type by encoding the leading underscore. So
+# "\0" -> _x0000_ and "_x0000_" -> _x005F_x0000_.
+# The following substitutions deal with those cases.
+#
+sub _escape_control_characters {
+
+    my $str = $_[0];
+
+    # Escape the escape.
+    $str =~ s/(_x[0-9a-fA-F]{4}_)/_x005F$1/g;
+
+    # Convert control character to the _xHHHH_ escape.
+    $str =~ s/([\x00-\x08\x0B-\x1F])/sprintf "_x%04X_", ord($1)/eg;
+
+    return $str;
+}
+
+
 1;
 
 

t/regression/escapes09.t

@@ -0,0 +1,90 @@
+###############################################################################
+#
+# Tests the output of Excel::Writer::XLSX against Excel generated files.
+#
+# Copyright 2000-2023, John McNamara, jmcnamara@cpan.org
+#
+# SPDX-License-Identifier: Artistic-1.0-Perl OR GPL-1.0-or-later
+#
+
+use lib 't/lib';
+use TestFunctions qw(_compare_xlsx_files _is_deep_diff);
+use strict;
+use warnings;
+
+use Test::More tests => 1;
+
+###############################################################################
+#
+# Tests setup.
+#
+my $filename     = 'escapes09.xlsx';
+my $dir          = 't/regression/';
+my $got_filename = $dir . "ewx_$filename";
+my $exp_filename = $dir . 'xlsx_files/' . $filename;
+
+my $ignore_members = [];
+
+my $ignore_elements = {};
+
+
+###############################################################################
+#
+# Test the creation of a simple Excel::Writer::XLSX file.
+#
+use Excel::Writer::XLSX;
+
+my $workbook  = Excel::Writer::XLSX->new( $got_filename );
+my $worksheet = $workbook->add_worksheet();
+my $chart     = $workbook->add_chart( type => 'line', embedded => 1 );
+
+# For testing, copy the randomly generated axis ids in the target xlsx file.
+$chart->{_axis_ids} = [ 52721920, 53133312 ];
+
+
+$worksheet->write( 0, 0, "Data\x1b[32m1" );
+$worksheet->write( 1, 0, "Data\x1b[32m2" );
+$worksheet->write( 2, 0, "Data\x1b[32m3" );
+$worksheet->write( 3, 0, "Data\x1b[32m4" );
+
+$worksheet->write( 0, 1, 10 );
+$worksheet->write( 1, 1, 20 );
+$worksheet->write( 2, 1, 10 );
+$worksheet->write( 3, 1, 30 );
+
+$chart->add_series(
+    categories => '=Sheet1!$A$1:$A$4',
+    values     => '=Sheet1!$B$1:$B$4'
+);
+
+$worksheet->insert_chart( 'E9', $chart );
+
+$workbook->close();
+
+
+###############################################################################
+#
+# Compare the generated and existing Excel files.
+#
+
+my ( $got, $expected, $caption ) = _compare_xlsx_files(
+
+    $got_filename,
+    $exp_filename,
+    $ignore_members,
+    $ignore_elements,
+);
+
+_is_deep_diff( $got, $expected, $caption );
+
+
+###############################################################################
+#
+# Cleanup.
+#
+unlink $got_filename;
+
+__END__
+
+
+