From c50662e1e81289c44b4da4107944221328bb5f1c Mon Sep 17 00:00:00 2001
From: nsfisis <nsfisis@gmail.com>
Date: Sun, 13 Jul 2025 15:37:47 +0900
Subject: fix: utf-8 decoding

---
 BUGS                                     |  9 +--------
 phpunit.xml                              |  4 ++++
 src/WebAssembly/BinaryFormat/Decoder.php | 31 ++-----------------------------
 3 files changed, 7 insertions(+), 37 deletions(-)

diff --git a/BUGS b/BUGS
index 3e88d14..ff37515 100644
--- a/BUGS
+++ b/BUGS
@@ -2,14 +2,7 @@
 
 ## Validation
 
+* AlignTest
 * ImportsTest
 * LinkingTest
-
-## Misc.
-
-* AlignTest
-* CustomTest
 * SkipStackGuardPageTest
-* Utf8CustomSectionIdTest
-* Utf8ImportFieldTest
-* Utf8ImportModuleTest
diff --git a/phpunit.xml b/phpunit.xml
index a6c6ac1..2e62c6f 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -29,6 +29,7 @@
             <file>tests/src/SpecTestsuites/Core/CallTest.php</file>
             <file>tests/src/SpecTestsuites/Core/ConstTest.php</file>
             <file>tests/src/SpecTestsuites/Core/ConversionsTest.php</file>
+            <file>tests/src/SpecTestsuites/Core/CustomTest.php</file>
             <file>tests/src/SpecTestsuites/Core/DataTest.php</file>
             <file>tests/src/SpecTestsuites/Core/ElemTest.php</file>
             <file>tests/src/SpecTestsuites/Core/EndiannessTest.php</file>
@@ -97,6 +98,9 @@
             <file>tests/src/SpecTestsuites/Core/UnreachedInvalidTest.php</file>
             <file>tests/src/SpecTestsuites/Core/UnreachedValidTest.php</file>
             <file>tests/src/SpecTestsuites/Core/UnwindTest.php</file>
+            <file>tests/src/SpecTestsuites/Core/Utf8CustomSectionIdTest.php</file>
+            <file>tests/src/SpecTestsuites/Core/Utf8ImportFieldTest.php</file>
+            <file>tests/src/SpecTestsuites/Core/Utf8ImportModuleTest.php</file>
             <file>tests/src/SpecTestsuites/Core/Utf8InvalidEncodingTest.php</file>
         </testsuite>
     </testsuites>
diff --git a/src/WebAssembly/BinaryFormat/Decoder.php b/src/WebAssembly/BinaryFormat/Decoder.php
index f0a5c29..ff23a5d 100644
--- a/src/WebAssembly/BinaryFormat/Decoder.php
+++ b/src/WebAssembly/BinaryFormat/Decoder.php
@@ -1119,35 +1119,8 @@ final class Decoder
      */
     private function implodeUtf8BytesToString(array $bytes): ?string
     {
-        $s = '';
-        $count = count($bytes);
-        for ($i = 0; $i < $count; $i++) {
-            if (($bytes[$i] & 0x80) === 0) {
-                $code = $bytes[$i];
-            } elseif (($bytes[$i] & 0xE0) === 0xC0) {
-                if ($count <= $i + 1) {
-                    return null;
-                }
-                $code = (($bytes[$i] & 0x1F) << 6) | ($bytes[$i + 1] & 0x3F);
-                $i++;
-            } elseif (($bytes[$i] & 0xF0) === 0xE0) {
-                if ($count <= $i + 2) {
-                    return null;
-                }
-                $code = (($bytes[$i] & 0x0F) << 12) | (($bytes[$i + 1] & 0x3F) << 6) | ($bytes[$i + 2] & 0x3F);
-                $i += 2;
-            } elseif (($bytes[$i] & 0xF8) === 0xF0) {
-                if ($count <= $i + 3) {
-                    return null;
-                }
-                $code = (($bytes[$i] & 0x07) << 18) | (($bytes[$i + 1] & 0x3F) << 12) | (($bytes[$i + 2] & 0x3F) << 6) | ($bytes[$i + 3] & 0x3F);
-                $i += 3;
-            } else {
-                return null;
-            }
-            $s .= mb_chr($code, 'UTF-8');
-        }
-        return $s;
+        $s = pack('C*', ...$bytes);
+        return mb_check_encoding($s, 'UTF-8') ? $s : null;
     }
 
     /**
-- 
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