WIP: udev/eudev replacement for Finit 5

.github/workflows/build.yml

@@ -34,7 +34,7 @@ jobs:
       - name: Install dependencies
         run: |
           sudo apt-get -y update
-          sudo apt-get -y install pkg-config tree jq libcap-dev libconfuse-dev
+          sudo apt-get -y install pkg-config tree jq libcap-dev libconfuse-dev libblkid-dev
           wget https://github.com/troglobit/libuev/releases/download/v2.4.1/libuev-2.4.1.tar.xz
           wget https://github.com/troglobit/libite/releases/download/v2.6.2/libite-2.6.2.tar.gz
           tar xf libuev-2.4.1.tar.xz

.github/workflows/coverity.yml

@@ -55,7 +55,7 @@ jobs:
       - name: Install dependencies
         run: |
           sudo apt-get -y update
-          sudo apt-get -y install pkg-config libcap-dev libconfuse-dev
+          sudo apt-get -y install pkg-config libcap-dev libconfuse-dev libblkid-dev
           wget https://github.com/troglobit/libuev/releases/download/v2.4.1/libuev-2.4.1.tar.xz
           wget https://github.com/troglobit/libite/releases/download/v2.6.2/libite-2.6.2.tar.gz
           tar xf libuev-2.4.1.tar.xz

.github/workflows/release.yml

@@ -18,7 +18,7 @@ jobs:
       - name: Installing dependencies ...
         run: |
           sudo apt-get -y update
-          sudo apt-get -y install pkg-config jq libcap-dev libconfuse-dev
+          sudo apt-get -y install pkg-config jq libcap-dev libconfuse-dev libblkid-dev
           wget https://github.com/troglobit/libuev/releases/download/v2.4.1/libuev-2.4.1.tar.xz
           wget https://github.com/troglobit/libite/releases/download/v2.6.2/libite-2.6.2.tar.gz
           tar xf libuev-2.4.1.tar.xz

.github/workflows/weekly.yml

@@ -34,7 +34,7 @@ jobs:
       - name: Install dependencies
         run: |
           sudo apt-get -y update
-          sudo apt-get -y install pkg-config jq libcap-dev libconfuse-dev
+          sudo apt-get -y install pkg-config jq libcap-dev libconfuse-dev libblkid-dev
           wget https://github.com/troglobit/libuev/releases/download/v2.4.1/libuev-2.4.1.tar.xz
           wget https://github.com/troglobit/libite/releases/download/v2.6.2/libite-2.6.2.tar.gz
           tar xf libuev-2.4.1.tar.xz

Makefile.am

@@ -1,5 +1,9 @@
 ACLOCAL_AMFLAGS    = -I m4
 SUBDIRS            = man plugins src system tmpfiles.d
+
+if KEVENTD
+SUBDIRS           += keventd
+endif
 dist_doc_DATA      = README.md LICENSE contrib/finit.conf
 
 if CONTRIB

configure.ac

@@ -16,6 +16,7 @@ AC_CONFIG_FILES([Makefile
 	man/Makefile
 	plugins/Makefile
 	src/Makefile
+	keventd/Makefile
 	system/Makefile system/10-hotplug.conf
 	test/test.env test/Makefile
 	test/lib/Makefile test/src/Makefile
@@ -118,7 +119,7 @@ AC_PLUGIN([resolvconf],    [no],  [Setup necessary files for resolvconf])
 AC_PLUGIN([x11-common],    [no],  [Console setup (for X)])
 AC_PLUGIN([netlink],       [yes], [Basic netlink plugin for IFUP/IFDN and GW events. Can be replaced with externally built plugin that links with libnl or similar.])
 AC_PLUGIN([hook-scripts],  [no],  [Trigger script execution from hook points])
-AC_PLUGIN([hotplug],       [yes], [Start udevd or mdev kernel event datamon])
+AC_PLUGIN([hotplug],       [no],  [Start udevd or mdev kernel event datamon])
 AC_PLUGIN([rtc],           [yes], [Save and restore RTC using hwclock])
 AC_PLUGIN([tty],           [yes], [Automatically activate new TTYs, e.g. USB-to-serial])
 AC_PLUGIN([urandom],       [yes], [Setup and save random seed at boot/shutdown])
@@ -171,7 +172,10 @@ AC_ARG_WITH(random-seed,
 	[random_seed=$withval], [random_seed=yes])
 
 AC_ARG_WITH(keventd,
-        AS_HELP_STRING([--with-keventd], [Enable built-in keventd, default: no]),, [with_keventd=no])
+        AS_HELP_STRING([--with-keventd], [Enable built-in keventd device manager, default: yes]),, [with_keventd=yes])
+
+AC_ARG_WITH(udev-rules,
+        AS_HELP_STRING([--without-udev-rules], [Skip install of curated udev rules under /lib/udev/rules.d, default: yes when keventd enabled]),, [with_udev_rules=yes])
 
 AC_ARG_WITH(sulogin,
         AS_HELP_STRING([--with-sulogin@<:@=USER@:>@], [Enable built-in sulogin, optional USER to request password for (default root), default: no.]),[sulogin=$withval],[with_sulogin=no])
@@ -318,7 +322,11 @@ AS_IF([test "x$rtc_file" != "xno"], [
 	AC_DEFINE_UNQUOTED(RTC_FILE, "$rtcfile_path", [Save and restore system time from this file if /dev/rtc is missing.])],[
 	AC_DEFINE_UNQUOTED(RTC_FILE, NULL)])
 
-AS_IF([test "x$with_keventd" != "xno"], [with_keventd=yes])
+AS_IF([test "x$with_keventd" != "xno"], [
+	with_keventd=yes
+	PKG_CHECK_MODULES([blkid], [blkid],, [
+		AC_MSG_ERROR([libblkid (util-linux) is required to build keventd.
+		Install the dev package (e.g. libblkid-dev) or disable keventd with --without-keventd])])])
 
 AS_IF([test "x$with_sulogin" != "xno"], [
 	AS_IF([test "x$sulogin" = "xyes"], [
@@ -351,6 +359,7 @@ AS_IF([test "x$with_plugin_path" != "xno"], [
 AM_CONDITIONAL(BASH,        [test "x$bash_dir"        != "xno"])
 AM_CONDITIONAL(STATIC,      [test "x$enable_static"    = "xyes"])
 AM_CONDITIONAL(KEVENTD,     [test "x$with_keventd"    != "xno"])
+AM_CONDITIONAL(UDEV_RULES,  [test "x$with_keventd"    != "xno" -a "x$with_udev_rules" != "xno"])
 AM_CONDITIONAL(SULOGIN,     [test "x$with_sulogin"    != "xno"])
 AM_CONDITIONAL(WATCHDOGD,   [test "x$with_watchdog"   != "xno"])
 AM_CONDITIONAL(LIBSYSTEMD,  [test "x$with_libsystemd" != "xno"])
@@ -434,7 +443,7 @@ Optional features:
   Install doc/..........: $enable_doc
   Install contrib/......: $enable_contrib
   Bash completion.......: $bash_completion_dir
-  Built-in keventd......: $with_keventd
+  Built-in keventd......: $with_keventd (blkid: $blkid_LIBS)
   Built-in sulogin......: $with_sulogin $sulogin
   Built-in watchdogd....: $with_watchdog $watchdog
   Built-in logrotate....: $enable_logrotate

doc/Makefile.am

@@ -6,6 +6,6 @@ dist_docs_DATA  = build.md cmdline.md commands.md conditions.md 	\
 		  distro.md example.md features.md index.md initctl.md	\
 		  keventd.md plugins.md requirements.md runlevels.md	\
 		  runparts.md service.md signals.md state-machine.md	\
-		  watchdog.md
+		  udev-matching.md watchdog.md
 dist_docs_DATA += img/logo.png img/svc-machine.png img/svc-machine.svg	\
 		  img/alpine-screenshot2.png

doc/conditions.md

@@ -177,15 +177,25 @@ Built-in Conditions
 
 Finit comes with a set of plugins for conditions:
 
- - `devmon` (built-in)
- - `netlink`
- - `pidfile`
+ - `keventd`: provides `<dev/...>`, `<class/...>`, `<driver/...>`, and
+   `<sys/pwr/...>`
+ - `devmon` (built-in fallback for `<dev/...>` without keventd)
+ - `netlink`: provides `<net/...>`
+ - `pidfile`: provides `<pid/...>`
  - `sys`
  - `usr`
 
-The `devmon` (built-in) plugin monitors `/dev` and `/dev/dir` for device
-nodes being created and removed.  It is active only when a run, task, or
-service has declared a `<dev/foo>` or `<dev/dir/bar>` condition.
+The `dev/` conditions are provided by `keventd`, the built-in device
+manager.  When keventd creates a device node in `/dev`, it also asserts
+the corresponding `dev/` condition.  When a device is removed, the
+condition is cleared.  If keventd is not in use (an external device
+manager like udevd is used instead), the `devmon` built-in provides the
+same conditions by monitoring `/dev` and `/dev/dir` with inotify.
+
+keventd also asserts `class/<subsystem>/<name>` for devices that have
+no `/dev` node, e.g. LEDs and DSA switch ports, and `driver/<name>`
+while a driver is bound to at least one device.  See
+[keventd](keventd.md) for details.
 
 The `pidfile` plugin recursively watches `/run/` for PID files created
 by the monitored services, and sets a corresponding condition in the
@@ -230,6 +240,8 @@ Built-in conditions:
 - `usr/foo`
 - `boot/arg`
 - `dev/node` and `dev/dir/node`
+- `class/<subsystem>/<name>`
+- `driver/<name>`
 
 > [!NOTE]
 > Here, `up` means administratively up, the interface flag `IFF_UP`.

doc/config/runlevels.md

@@ -125,8 +125,10 @@ Load kernel modules, each with optional arguments.  Similar to the
 Deprecated, there is both a `modules-load.so` and a `modprobe.so` plugin
 that can handle module loading better.  The former supports loading from
 `/etc/modules-load.d/`, the latter uses kernel modinfo to automatically
-load (or coldplug) every required module.  For hotplug we recommend the
-BusyBox mdev tool, add to `/etc/mdev.conf`:
+load (or coldplug) every required module.  Hotplug module loading is
+handled by [keventd](../keventd.md), the built-in device manager.  On
+systems using the hotplug plugin with BusyBox mdev instead, add to
+`/etc/mdev.conf`:
 
     $MODALIAS=.*  root:root       0660    @modprobe -b "$MODALIAS"