uri: Make the .free_uri handlers safe to call with NULL (php#19627)

* uri: Make the `.free_uri` handlers safe to call with `NULL`

The `php_uri_free()` function already unconditionally called `->free_uri()` and
thus couldn't be safely used when the `->uri` was `NULL` for some reason.

The lexbor implementation was already safe, because `lxb_url_destroy()` is
guaranteed to be a noop for `NULL`.

* uri: Stop checking for `NULL` before calling `->free_uri()`

This implicitly fixes an `UNEXPECTED(…->uri != NULL)` in `uri_free_obj_handler`
that likely should have read `EXPECTED` instead.

* uri: Remove unnecessary reset of `->uri` to `NULL` in `php_uri_object_handler_free()`

* uri: Document the requirement of `free_uri()` being safe with `NULL`

Author: TimWolla

ext/uri/php_uri.c

@@ -830,9 +830,7 @@ static void uri_unserialize(INTERNAL_FUNCTION_PARAMETERS)
 	}
 
 	uri_internal_t *internal_uri = uri_internal_from_obj(object);
-	if (internal_uri->uri != NULL) {
-		internal_uri->parser->free_uri(internal_uri->uri);
-	}
+	internal_uri->parser->free_uri(internal_uri->uri);
 	internal_uri->uri = internal_uri->parser->parse_uri(Z_STRVAL_P(uri_zv), Z_STRLEN_P(uri_zv), NULL, NULL, true);
 	if (internal_uri->uri == NULL) {
 		zend_throw_exception_ex(NULL, 0, "Invalid serialization data for %s object", ZSTR_VAL(object->ce->name));
@@ -1025,12 +1023,7 @@ PHPAPI void php_uri_object_handler_free(zend_object *object)
 {
 	uri_object_t *uri_object = uri_object_from_obj(object);
 
-	if (UNEXPECTED(uri_object->internal.uri != NULL)) {
-		uri_object->internal.parser->free_uri(uri_object->internal.uri);
-		uri_object->internal.parser = NULL;
-		uri_object->internal.uri = NULL;
-	}
-
+	uri_object->internal.parser->free_uri(uri_object->internal.uri);
 	zend_object_std_dtor(&uri_object->std);
 }
 

ext/uri/php_uri_common.h

@@ -122,7 +122,7 @@ typedef struct uri_parser_t {
 	/**
 	 * Frees the provided URI.
 	 *
-	 * @param uri The input URI
+	 * @param uri The URI to free. Must do nothing if NULL.
 	 */
 	void (*free_uri)(void *uri);
 

ext/uri/uri_parser_php_parse_url.c

@@ -158,6 +158,10 @@ static void uri_parser_php_parse_url_free(void *uri)
 {
 	php_url *parse_url_uri = uri;
 
+	if (UNEXPECTED(parse_url_uri == NULL)) {
+		return;
+	}
+
 	php_url_free(parse_url_uri);
 }
 

ext/uri/uri_parser_rfc3986.c

@@ -554,10 +554,14 @@ ZEND_ATTRIBUTE_NONNULL static zend_string *php_uri_parser_rfc3986_to_string(void
 	return uri_string;
 }
 
-ZEND_ATTRIBUTE_NONNULL static void php_uri_parser_rfc3986_free(void *uri)
+static void php_uri_parser_rfc3986_free(void *uri)
 {
 	php_uri_parser_rfc3986_uris *uriparser_uris = uri;
 
+	if (UNEXPECTED(uriparser_uris == NULL)) {
+		return;
+	}
+
 	uriFreeUriMembersMmA(&uriparser_uris->uri, mm);
 	uriFreeUriMembersMmA(&uriparser_uris->normalized_uri, mm);