Imply UTF8 validity in implode function

Author: mvorisek

Zend/zend_string.h

@@ -241,7 +241,9 @@ static zend_always_inline zend_string *zend_string_dup(zend_string *s, bool pers
 	if (ZSTR_IS_INTERNED(s)) {
 		return s;
 	} else {
-		return zend_string_init(ZSTR_VAL(s), ZSTR_LEN(s), persistent);
+		zend_string *res = zend_string_init(ZSTR_VAL(s), ZSTR_LEN(s), persistent);
+        ZSTR_COPY_CONCAT_PROPERTIES(res, s);
+		return res;
 	}
 }
 

ext/standard/string.c

@@ -955,11 +955,14 @@ PHPAPI void php_implode(const zend_string *glue, HashTable *pieces, zval *return
 
 	ptr = strings = do_alloca((sizeof(*strings)) * numelems, use_heap);
 
+	uint32_t flags = ZSTR_GET_COPYABLE_CONCAT_PROPERTIES(glue);
+
 	ZEND_HASH_FOREACH_VAL(pieces, tmp) {
 		if (EXPECTED(Z_TYPE_P(tmp) == IS_STRING)) {
 			ptr->str = Z_STR_P(tmp);
 			len += ZSTR_LEN(ptr->str);
 			ptr->lval = 0;
+			flags &= ZSTR_GET_COPYABLE_CONCAT_PROPERTIES(ptr->str);
 			ptr++;
 		} else if (UNEXPECTED(Z_TYPE_P(tmp) == IS_LONG)) {
 			zend_long val = Z_LVAL_P(tmp);
@@ -978,12 +981,14 @@ PHPAPI void php_implode(const zend_string *glue, HashTable *pieces, zval *return
 			ptr->str = zval_get_string_func(tmp);
 			len += ZSTR_LEN(ptr->str);
 			ptr->lval = 1;
+			flags &= ZSTR_GET_COPYABLE_CONCAT_PROPERTIES(ptr->str);
 			ptr++;
 		}
 	} ZEND_HASH_FOREACH_END();
 
 	/* numelems cannot be 0, we checked above */
 	str = zend_string_safe_alloc(numelems - 1, ZSTR_LEN(glue), len, 0);
+	GC_ADD_FLAGS(str, flags);
 	cptr = ZSTR_VAL(str) + ZSTR_LEN(str);
 	*cptr = 0;
 

ext/zend_test/tests/strings_marked_as_utf8.phpt

@@ -115,6 +115,33 @@ $string = "\xff";
 $string_concat = str_repeat($string, 100);
 var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
 
+echo "implode:\n";
+$arr = ['a', 'b'];
+$string_concat = implode('', $arr);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('|', $arr);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', ['c', ...$arr]);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', [...$arr, 'c']);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', ["\xff", ...$arr]);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', [...$arr, "\xff"]);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode("\xff", $arr);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', []);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode("\xff", []);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', ['a']);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode("\xff", ['a']);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', [1, 1.0, 'a']);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+
 ?>
 --EXPECT--
 Empty strings:
@@ -159,3 +186,16 @@ bool(true)
 str_repeat:
 bool(true)
 bool(false)
+implode:
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(false)
+bool(false)
+bool(false)
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(true)