Drop-in replacement for libudev intended to work with any device manager

We all know that systemd is very hostile towards portability. Udev inherited the same problem by exposing a very badly designed library interface. This is dramatically reduces portability, user choice and basically creates vendor lock-in because library interface highly tied to udev daemon.

Another udev problem is non-portable home-grown language called "udev rules". Udev authors definitely don't know(or care) why it's better to avoid reinventing the wheel. Strictly speaking, I think they did that on purpose to overcomplicate udev as much as possible. Why? So that only authors(RedHat/IBM) can rule and dictate the future of udev. The recent eudev death only proves that it's really hard to support such unmaintainable mess.

Udev hwdb is yet another illustration of systemd-like approach. What the hell "userspace /dev" has to do with parsing hardware database(pci.ids, usb.ids) and setting/remapping buttons? Udev smells like systemd by trying to implement all possible functionality in the single daemon/code base. Standalone UNIX-way programs much better suited for such purposes.

Keep in mind that libudev-zero isn't ideal. Here is some pros/cons:

• Very portable. Doesn't depend on GNU features.
• No lock-in. Any device manager can be used, even smdev and CONFIG_UEVENT_HELPER.
• Source code is much cleaner than udev because of less abstractions and clever code.

• Udev rules must be converted to shell script in order to work with any device manager.
• Udev hwdb interface isn't implemented. pciutils and usbutils will not display any meaningful info.
• Many functions and interfaces still aren't implemented, which may lead to breakage in some programs.

• dosfstools - requires udev_enumerate_add_match_parent()
• PulseAudio - highly depends on udev internal properties. workaround
• udisks2 - highly depends on udev internal properties
• android-tools - requires udev rules for non-root usage
• NetworkManager - needs investigation
• libgudev - needs investigation
• PipeWire - depends on udev internal properties. patch
• ldm - depends on udev internal properties
• lvm2 - uses deprecated udev_queue API
• cups - needs investigation
• ???

• C99 compiler (build time)
• POSIX make (build time)
• POSIX & XSI libc
• Linux >= 2.6.39

make
make PREFIX=/usr install

Note that hotplugging support is fully optional. You can skip this step if you don't have a need for the hotplugging capability.

If you're using mdev-like device manager, refer to mdev.conf for config example.

If you're using other device manager, you need to configure it to rebroadcast kernel uevents. You can do this by either patching(see below) device manager or simply executing helper.c for each uevent.

If you're developing your own device manager, you need to rebroadcast kernel uevents to 0x4 netlink group of NETLINK_KOBJECT_UEVENT. This is required because libudev-zero can't simply listen to kernel uevents due to potential race conditions. Refer(but don't copy blindly) to helper.c for example how it could be implemented in C.

Don't hesitate to ask me everything you don't understand. I'm usually hanging around in #kisslinux at libera.chat, but you can also email me or open an issue here.

1. Write a better cross-platform(*nix, maybe macos and windows) device enumeration library.
2. Convince mainstream apps(libinput, wlroots, ...) to use new library instead of libudev.
3. Declare libudev as obsolete library and archive this project.

You can send a donation to BTC: 1BwrcsgtWZeLVvNeEQSg4A28a3yrGN3FpK

Thank you very much!