From: Nikita Popov <nikita.ppv@gmail.com>
Date: Wed, 6 May 2020 20:55:03 +0000 (+0200)
Subject: Fix assertion failure when failing to detect encoding
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=71f48260af4b75461a7a096908883375b157b896;p=php

Fix assertion failure when failing to detect encoding

Looks like prior to 7.3 this just passed the original string
through. Since 7.3 it returns false. Let's stick with that
behavior.
---

diff --git a/ext/mbstring/mbstring.c b/ext/mbstring/mbstring.c
index f636d51b02..a529f84809 100644
--- a/ext/mbstring/mbstring.c
+++ b/ext/mbstring/mbstring.c
@@ -2489,9 +2489,6 @@ MBSTRING_API char *php_mb_convert_encoding(const char *input, size_t length, con
 	if (output_len) {
 		*output_len = 0;
 	}
-	if (!input) {
-		return NULL;
-	}
 
 	/* pre-conversion encoding */
 	ZEND_ASSERT(num_from_encodings >= 1);
@@ -2507,7 +2504,7 @@ MBSTRING_API char *php_mb_convert_encoding(const char *input, size_t length, con
 			&string, from_encodings, num_from_encodings, MBSTRG(strict_detection));
 		if (!from_encoding) {
 			php_error_docref(NULL, E_WARNING, "Unable to detect character encoding");
-			from_encoding = &mbfl_encoding_pass;
+			return NULL;
 		}
 	}
 
diff --git a/ext/mbstring/tests/mb_convert_encoding_failed_detection.phpt b/ext/mbstring/tests/mb_convert_encoding_failed_detection.phpt
new file mode 100644
index 0000000000..961af505ec
--- /dev/null
+++ b/ext/mbstring/tests/mb_convert_encoding_failed_detection.phpt
@@ -0,0 +1,11 @@
+--TEST--
+mb_convert_encoding() when encoding detection fails
+--FILE--
+<?php
+
+var_dump(mb_convert_encoding("\xff", "ASCII", ["UTF-8", "UTF-16"]));
+
+?>
+--EXPECTF--
+Warning: mb_convert_encoding(): Unable to detect character encoding in %s on line %d
+bool(false)