Html Reader Not Handling non-ASCII Data Correctly

Fix PHPOffice#2942. Code was changed by PHPOffice#2894 because PHP8.2 will deprecate how it was being done. See linked issue for more details. Dom loadhtml assumes ISO-8859-1 in the absence of a charset attribute or equivalent, and there is no way to override that assumption. Sigh. The suggested replacements are unsuitable in one way or another. I think this will work with minimal disruption (replace ampersand, less than, and greater than with entities representing illegal characters, then use htmlentities, then restore ampersand, less than, and greater than).

src/PhpSpreadsheet/Reader/Html.php

@@ -201,7 +201,7 @@ private static function containsTags(string $data): bool
     /**
      * Loads Spreadsheet from file.
      */
-    protected function loadSpreadsheetFromFile(string $filename): Spreadsheet
+    public function loadSpreadsheetFromFile(string $filename): Spreadsheet
     {
         // Create new Spreadsheet
         $spreadsheet = new Spreadsheet();
@@ -651,6 +651,22 @@ public function loadIntoExisting($filename, Spreadsheet $spreadsheet)
         // Reload the HTML file into the DOM object
         try {
             $convert = $this->securityScanner->scanFile($filename);
+            /*if (substr($convert, 0, 6) !== '<?xml ') {
+                $convert = '<?xml encoding = "UTF-8">' . $convert;
+            }*/
+            // Surrogate characters should not be valid in html.
+            // Ampersand must be replaced before < and >.
+            $convert = str_replace(
+                ['&', '<', '>'],
+                ['&#xd800;', '&#xd801;', '&#xd802;'],
+                $convert
+            );
+            $convert = htmlentities($convert, ENT_NOQUOTES, 'UTF-8');
+            $convert = str_replace(
+                ['&amp;#xd800;', '&amp;#xd801;', '&amp;#xd802;'],
+                ['&', '<', '>'],
+                $convert
+            );
             $loaded = $dom->loadHTML($convert);
         } catch (Throwable $e) {
             $loaded = false;
@@ -674,6 +690,22 @@ public function loadFromString($content, ?Spreadsheet $spreadsheet = null): Spre
         //    Reload the HTML file into the DOM object
         try {
             $convert = $this->securityScanner->scan($content);
+            /*if (substr($convert, 0, 6) !== '<?xml ') {
+                $convert = '<?xml encoding = "UTF-8">' . $convert;
+            }*/
+            // Surrogate characters should not be valid in html.
+            // Ampersand must be replaced before < and >.
+            $convert = str_replace(
+                ['&', '<', '>'],
+                ['&#xd800;', '&#xd801;', '&#xd802;'],
+                $convert
+            );
+            $convert = htmlentities($convert, ENT_NOQUOTES, 'UTF-8');
+            $convert = str_replace(
+                ['&amp;#xd800;', '&amp;#xd801;', '&amp;#xd802;'],
+                ['&', '<', '>'],
+                $convert
+            );
             $loaded = $dom->loadHTML($convert);
         } catch (Throwable $e) {
             $loaded = false;

tests/PhpSpreadsheetTests/Reader/Html/Issue2942Test.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Html;
+
+use PhpOffice\PhpSpreadsheet\Reader\Html;
+use PHPUnit\Framework\TestCase;
+
+class Issue2942Test extends TestCase
+{
+    public function testLoadFromString(): void
+    {
+        $content = '<table><tbody><tr><td>éàâèî</td></tr></tbody></table>';
+        $reader = new Html();
+        $spreadsheet = $reader->loadFromString($content);
+        $sheet = $spreadsheet->getActiveSheet();
+        self::assertSame('éàâèî', $sheet->getCell('A1')->getValue());
+    }
+
+    public function testLoadFromFile(): void
+    {
+        $file = 'tests/data/Reader/HTML/utf8chars.html';
+        $reader = new Html();
+        $spreadsheet = $reader->loadSpreadsheetFromFile($file);
+        $sheet = $spreadsheet->getActiveSheet();
+        self::assertSame('éàâèî', $sheet->getCell('A1')->getValue());
+        self::assertSame('αβγδε', $sheet->getCell('B1')->getValue());
+    }
+}

tests/data/Reader/HTML/utf8chars.html

@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html>
+<head>
+<!-- deliberately do not identify charset for this test -->
+<title>Test Utf-8 characters</title>
+</head>
+<body>
+<table>
+    <tbody>
+    <tr>
+        <td>éàâèî</td>
+        <td>αβγδε</td>
+    </tr>
+    </tbody>
+</table>
+</body>
+</html>