From bf2d930fa12de997920eef493d9fcce1580c4f44 Mon Sep 17 00:00:00 2001 From: Luca Boccassi Date: Tue, 25 Apr 2023 00:37:51 +0100 Subject: macro: add helper for module origin id These need to be redefined in every module that we need to guard, so add a macro --- src/basic/origin-id.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 src/basic/origin-id.h (limited to 'src/basic') diff --git a/src/basic/origin-id.h b/src/basic/origin-id.h new file mode 100644 index 0000000000..c55b0a368a --- /dev/null +++ b/src/basic/origin-id.h @@ -0,0 +1,36 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +#pragma once + +#include + +#include "random-util.h" + +/* This pattern needs to be repeated exactly in multiple modules, so macro it. + * To ensure an object is not passed into a different module (e.g.: when two shared objects statically + * linked to libsystemd get loaded in the same process, and the object created by one is passed to the + * other, see https://github.com/systemd/systemd/issues/27216), create a random static global random + * (mixed with PID, so that we can also check for reuse after fork) that is stored in the object and + * checked by public API on use. */ +#define _DEFINE_ORIGIN_ID_HELPERS(type, name, scope) \ +static uint64_t origin_id; \ + \ +static void origin_id_initialize(void) { \ + origin_id = random_u64(); \ +} \ + \ +static uint64_t origin_id_query(void) { \ + static pthread_once_t once = PTHREAD_ONCE_INIT; \ + assert_se(pthread_once(&once, origin_id_initialize) == 0); \ + return origin_id ^ getpid_cached(); \ +} \ + \ +scope bool name##_origin_changed(type *p) { \ + assert(p); \ + return p->origin_id != origin_id_query(); \ +} + +#define DEFINE_ORIGIN_ID_HELPERS(type, name) \ + _DEFINE_ORIGIN_ID_HELPERS(type, name,); + +#define DEFINE_PRIVATE_ORIGIN_ID_HELPERS(type, name) \ + _DEFINE_ORIGIN_ID_HELPERS(type, name, static); -- cgit v1.2.1