From 47932af96bb36161becbe034e1765077730d08e2 Mon Sep 17 00:00:00 2001
From: b <rowerynaksiezycu@gmail.com>
Date: Mon, 19 Sep 2022 21:10:59 +0000
Subject: [PATCH] introduce masked replacement to avoid undefined behavior

---
 configure.pl | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/configure.pl b/configure.pl
index 68c2487..9952e8d 100755
--- a/configure.pl
+++ b/configure.pl
@@ -494,6 +494,28 @@ sub replace {
 	return (1, $before.$replacement.$after);
 }
 
+# replace but with mask to avoid duplicated replacement
+sub replace_masked {
+	(my $text, my $mask, my $to_replace, my $replacement) = @_;
+	
+	my $ind = index($mask, $to_replace);
+	if ($ind <0) {
+		return (0, $text, $mask);
+	}
+	my $len = length($to_replace);
+	
+	my $text_before = substr($text, 0, $ind);
+	my $mask_before = substr($mask, 0, $ind);
+	my $mask_insert = "\r" x length($replacement); # CR can never appear in $text
+	my $text_after = substr($text, $ind+$len);
+	my $mask_after = substr($mask, $ind+$len);
+	
+	$text = $text_before.$replacement.$text_after;
+	$mask = $mask_before.$mask_insert.$mask_after;
+	
+	return (1, $text, $mask);
+}
+
 sub print_debug {
 	(my $depth, my $text) = @_;
 	if ($debug_enabled) {
@@ -976,9 +998,10 @@ sub convert_file {
 				next LINE;
 			}
 		}
+		my $mask = $line;
 		foreach my $key (keys %replace_keyword) {
 			do {
-				($status, $line) = replace($line, $key, $replace_keyword{$key});
+				($status, $line, $mask) = replace_masked($line, $mask, $key, $replace_keyword{$key});
 			} while ($status);
 		}
 		print $out "$line\n";
-- 
2.30.2