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Author SHA1 Message Date
Joachim Wiberg 67d61a8282 keventd: add udev rules engine
Transform keventd from a power-supply monitor + basic hotplug handler into
a full udev-compatible device manager.

Rules engine (rules.c):
- Full .rules file parser covering all udev key types: ACTION, KERNEL,
  SUBSYSTEM, DEVPATH, ENV, ATTR, SYSCTL, TAG, RESULT, PROGRAM, TEST,
  parent-chain KERNELS/SUBSYSTEMS/ATTRS/DRIVERS, and more
- Pattern matching: plain string, fnmatch glob, and pipe-separated alternatives
- Operators: ==, !=, =, +=, -=, :=
- Assignments: NAME=, MODE=, OWNER=, GROUP=, SYMLINK+=, ENV{k}=, TAG+=, RUN+=
- IMPORT{program|file|builtin|parent|cmdline|db}=
- PROGRAM= with stdout capture for subsequent RESULT== matching
- GOTO=/LABEL= flow control
- Loads *.rules from /lib/udev/rules.d, /run/udev/rules.d, /etc/udev/rules.d
  and an optional extra directory (-r DIR); reloads on SIGHUP

Builtin framework (builtin.c):
- kmod:     load module by MODALIAS or explicit alias
- hwdb:     match device against *.hwdb text files in udev hwdb dirs; builds
	    correct lookup key per subsystem — evdev:input:b*v*p*e* for input,
	    usb:v*p* for USB, raw modalias for PCI/platform
- path_id:  build stable ID_PATH / ID_PATH_TAG from sysfs topology (PCI, USB,
	    ATA, NVMe, platform, ACPI, virtio)
- usb_id:   read idVendor/idProduct/bcdDevice/serial from sysfs; look up
	    ID_VENDOR_FROM_DATABASE and ID_MODEL_FROM_DATABASE from usb.ids
	    (hwdata package) when available; silent fallback when absent
- input_id: classify input devices (keyboard, mouse, joystick, touchscreen,
	    touchpad) from evdev capability bitmasks in sysfs
- net_id:   generate predictable names — MAC-based enx<mac> and PCI-slot-based
	    enp<bus>s<dev>[f<func>]
- blkid:    probe filesystem type, UUID, and label via libblkid; sets ID_FS_*
	    and ID_PART_TABLE_* properties

Network interface renaming (uevent.c):
- netdev_add() renames interfaces via SIOCSIFNAME when a NAME= rule matched,
  then sets the Finit dev/ condition on the final name; and any setup using
  persistent interface naming via udev rules

Device node and symlink improvements (uevent.c):
- NAME=, MODE=, OWNER=, GROUP= overrides from matched rules applied at
  mknod/chown time, falling back to the built-in permission table
- SYMLINK+= links from rules applied alongside built-in by-id/by-path links

Device property database (udevdb.c):
- Persist per-device E:/S:/I: records to /run/udev/data/ on ADD/CHANGE,
  delete on REMOVE; IMPORT{db}= restores saved properties into event env

Build:
- libblkid (util-linux) is now required for keventd

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
2026-08-16 22:03:31 +02:00