unserialize does not allow empty strings

Author: SakiTakamachi

ext/bcmath/bcmath.c

@@ -1738,7 +1738,7 @@ PHP_METHOD(BcMath_Number, __unserialize)
 	ZEND_PARSE_PARAMETERS_END();
 
 	zval *zv = zend_hash_str_find(props, "value", sizeof("value")-1);
-	if (!zv || Z_TYPE_P(zv) != IS_STRING) {
+	if (!zv || Z_TYPE_P(zv) != IS_STRING || Z_STRLEN_P(zv) == 0) {
 		goto fail;
 	}
 

ext/bcmath/tests/number/unserialize_error.phpt

@@ -11,12 +11,26 @@ try {
     echo $e->getMessage() . "\n";
 }
 
-try {
-    unserialize('O:13:"BcMath\Number":1:{s:5:"value";s:1:"a";}');
-} catch (Exception $e) {
-    echo $e->getMessage();
+echo "\n";
+$cases = [
+    'O:13:"BcMath\Number":1:{s:5:"value";s:1:"a";}',
+    'O:13:"BcMath\Number":1:{s:5:"value";s:0:"";}',
+    'O:13:"BcMath\Number":0:{}',
+    'O:13:"BcMath\Number":1:{s:5:"value";i:1;}',
+];
+
+foreach ($cases as $case) {
+    try {
+        unserialize($case);
+    } catch (Exception $e) {
+        echo $e->getMessage() . "\n";
+    }
 }
 ?>
 --EXPECT--
 Cannot modify readonly property BcMath\Number::$value
+
+Invalid serialization data for BcMath\Number object
+Invalid serialization data for BcMath\Number object
+Invalid serialization data for BcMath\Number object
 Invalid serialization data for BcMath\Number object