简单的C或C ++ API，用于控制systemd服务

问题描述

我想编写C / C ++应用程序，并提供API以使其直接与 systemd -通信管理服务。实际上，我希望我的应用程序能够执行 systemctl start service_name@unit_number.service 的等效功能，而无需使用 system（）， popen（）或 exec（）调用（硬性要求 ）。

I'd like to write C/C++ applications and provide an API for them to communicate directly with systemd-managed services. Effectively, I'd like my applications to be able to do the equivalent of systemctl start service_name@unit_number.service without using system(), popen(), or exec() calls (hard requirement).

是否有用于通信的简单 C / C ++ API使用 systemd ，并假定使用 systemd 219版（即CentOS v7.4，也是一个硬要求 >）？

Is there a simple C/C++ API for communicating with systemd, assuming systemd version 219 (i.e. CentOS v7.4, also a hard requirement)?

1. 我在网上搜索了示例在C / C ++和systemd 管理的服务rel = noreferrer>找到了关于该主题的奇怪讨论，但没有找到任何好的例子。


2. 我总是可以对，但随后可能会违反GPL许可。




4. ，因为维护者自己会声明 如果您使用此。

1. I've scoured online for examples of controlling systemd-managed services in C/C++ and found the odd discussion on the topic, but haven't found any good examples.
2. I could always reverse-engineer systemctl version 219 from source, but then I potentially run afoul of GPL licensing.
3. Since I'm stuck with CentOS v7.4, which means I can't get at version 221 or later of systemd, I can't use the newer "SD Bus" API. Nobody would allow manually upgrading libsystemd just for an application-specific benefit, and I'm apparently not the first person to raise this concern.
4. I'm hesitant to use the low-level C API for DBUS, since the maintainers themselves state "If you use this low-level API directly, you're signing up for some pain.".

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硬要求

• systemd v219。


• CentOS v7.4


• C / C ++。


• 否 system（） / 对 systemctl CLI实用程序的popen（） / exec（）调用。


• 非传播许可证（即LGPLv2可以，但最好使用BSD / MIT）。



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Hard Requirements

• systemd v219.
• CentOS v7.4
• C/C++.
• No system()/popen()/exec() calls to the systemctl CLI utility.
• Non-propagating license (i.e. LGPLv2 is OK, though BSD/MIT is preferred).

我可以使用更简单的API吗？在CentOS v7.4上的ld使用（即使我必须自己提供共享库）也可以用于通过C /以简单，可靠的方式与 systemd 进行通信C ++代码？ 如果现有的 libdbus-1.so API很复杂但仍然可靠，并且我可以围绕它创建一个可靠/稳定的包装器库，那么我愿意探索。此外，如果可以手动构建和部署独立于 systemd 的SD-BUS组件并使用它们，而无需修改/升级 systemd 库/守护程序已经在系统上了，我也有可能走这条路线。

Is there a simpler API that I could use on CentOS v7.4 (even if I have to supply the shared library myself) that can be used to communicate with systemd in a simple, reliable manner directly via C/C++ code? If the existing libdbus-1.so API is complicated but still reliable, and I can create a reliable/stable wrapper library around it, I'm open to exploring that option. Also, if it's possible to manually build and deploy the SD-BUS components independent of systemd and use them without having to modify/upgrade the systemd library/daemon already on the system, I could potentially go that route too.



• 只要不要求完全发布所有源代码，我愿意使用成熟的C ++库。



谢谢。

推荐答案

如您所知，您只应使用dbus库与systemd进行交互，没有其他支持的方法。
即使您取消了不执行二进制文件的要求，它也仍然会令人皱眉，因为* ctl工具是命令行用户界面，无意或设计为从其他程序调用。

As you already figured out, you should only interact with systemd using a dbus library, there is no other supported way to do so.Even if you lifted the requirement of no execution of binaries, it will remain frowned upon, as the *ctl tools are command line user interfaces not intended or designed to be called from other programs.

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