[RFC] Boot refactor

configure.ac

@@ -101,6 +101,7 @@ AC_ARG_ENABLE(contrib,
 enable_all_plugins=auto
 AC_PLUGIN([alsa-utils],    [no],  [Save and restore ALSA sound settings using alsactl])
 AC_PLUGIN([dbus],          [no],  [Setup and start system message bus, D-Bus])
+AC_PLUGIN([hotplug],       [yes], [Setup and start udev or mdev hotplug daemon])
 AC_PLUGIN([inetd-echo],    [no],  [Inetd plugin: echo server, RFC862])
 AC_PLUGIN([inetd-chargen], [no],  [Inetd plugin: character generator, RFC864])
 AC_PLUGIN([inetd-daytime], [no],  [Inetd plugin: daytime server, RFC867])

contrib/fstab.bb

@@ -0,0 +1,15 @@
+# This is a basic /etc/fstab that mounts up all of the virtual filesystems
+# that older versions of Finit used to mount internally. It can serve as a
+# starting point for systems running Busybox's mount implementation. Make
+# sure that CONFIG_FEATURE_MOUNT_HELPERS enabled; as this is required
+# create the /dev/{pts,shm} directories.
+
+devtmpfs	/dev		devtmpfs	defaults		0	0
+mkdir#-p	/dev/pts	helper		none			0	0
+devpts		/dev/pts	devpts		mode=620,ptmxmode=0666	0	0
+mkdir#-p	/dev/shm	helper		none			0	0
+tmpfs		/dev/shm	tmpfs		mode=0777		0	0
+proc		/proc		proc		defaults		0	0
+tmpfs		/tmp		tmpfs		mode=1777,nosuid,nodev	0	0
+tmpfs		/run		tmpfs		mode=0755,nosuid,nodev	0	0
+sysfs		/sys		sysfs		defaults		0	0

doc/plugins.md

@@ -42,6 +42,9 @@ For your convenience a set of *optional* plugins are available:
 
 * *discard.so*: RFC 863 plugin.  Start as inetd service, like time below.
 
+* *hotplug.so*: Setup and start either udev or mdev hotplug daemon, if
+  available.
+
 * *rtc.so*: Restore and save system clock from/to RTC on boot/halt.
 
 * *initctl.so*: Extends finit with a traditional `initctl` functionality.

plugins/Makefile.am

@@ -17,6 +17,10 @@ if BUILD_DBUS_PLUGIN
 libplug_la_SOURCES += dbus.c
 endif
 
+if BUILD_HOTPLUG_PLUGIN
+libplug_la_SOURCES += hotplug.c
+endif
+
 if INETD
 if BUILD_INETD_ECHO_PLUGIN
 libplug_la_SOURCES += echo.c
@@ -62,6 +66,10 @@ if BUILD_DBUS_PLUGIN
 pkglib_LTLIBRARIES += dbus.la
 endif
 
+if BUILD_HOTPLUG_PLUGIN
+pkglib_LTLIBRARIES += hotplug.la
+endif
+
 if INETD
 if BUILD_INETD_ECHO_PLUGIN
 pkglib_LTLIBRARIES += echo.la

plugins/hotplug.c

@@ -0,0 +1,110 @@
+/* Heuristically find and initialize a suitable hotplug daemon
+ *
+ * Copyright (c) 2012-2020 Joachim Wiberg <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include <stdio.h>
+
+#include "config.h"
+#include "conf.h"
+#include "finit.h"
+#include "helpers.h"
+#include "plugin.h"
+#include "service.h"
+
+static void setup(void *arg)
+{
+	char cmd[256];
+	char *path;
+
+	/*
+	 * Populate /dev and prepare for runtime events from kernel.
+	 * Prefer udev if mdev is also available on the system.
+	 */
+	path = which("udevd");
+	if (!path)
+		path = which("/lib/systemd/systemd-udevd");
+	if (path) {
+		/* Register udevd as a monitored service */
+		snprintf(cmd, sizeof(cmd), "[S12345789] pid:udevd %s "
+			 "-- Device event managing daemon", path);
+		if (service_register(SVC_TYPE_SERVICE, cmd, global_rlimit, NULL)) {
+			_pe("Failed registering %s", path);
+		} else {
+			snprintf(cmd, sizeof(cmd), ":1 [S] <svc%s> "
+				 "udevadm trigger -c add -t devices "
+				 "-- Requesting device events", path);
+			service_register(SVC_TYPE_RUN, cmd, global_rlimit, NULL);
+
+			snprintf(cmd, sizeof(cmd), ":2 [S] <svc%s> "
+				 "udevadm trigger -c add -t subsystems "
+				 "-- Requesting subsystem events", path);
+			service_register(SVC_TYPE_RUN, cmd, global_rlimit, NULL);
+		}
+
+		free(path);
+
+		/* Debian has this little script to copy generated
+		 * rules while the system was read-only. TODO: When
+		 * this functionality was hardcoded in finit.c, this
+		 * call was made in crank_worker(). Now that
+		 * filesystems are mounted earlier we should be able
+		 * to make this call directly after the triggers have
+		 * run, but this has not been tested AT ALL. */
+		if (fexist("/lib/udev/udev-finish"))
+			run_interactive("/lib/udev/udev-finish", "Finalizing udev");
+	} else {
+		path = which("mdev");
+		if (path) {
+			/* Embedded Linux systems usually have BusyBox mdev */
+			if (log_is_debug())
+				touch("/dev/mdev.log");
+
+			snprintf(cmd, sizeof(cmd), "%s -s", path);
+			free(path);
+
+			run_interactive(cmd, "Populating device tree");
+		}
+	}
+}
+
+static plugin_t plugin = {
+	.name = __FILE__,
+	.hook[HOOK_BASEFS_UP] = {
+		.cb  = setup
+	},
+};
+
+PLUGIN_INIT(plugin_init)
+{
+	plugin_register(&plugin);
+}
+
+PLUGIN_EXIT(plugin_exit)
+{
+	plugin_unregister(&plugin);
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */

src/conf.c

@@ -59,6 +59,22 @@ static TAILQ_HEAD(head, conf_change) conf_change_list = TAILQ_HEAD_INITIALIZER(c
 static int parse_conf(char *file);
 static void drop_changes(void);
 
+static void hide_args(int argc, char *argv[])
+{
+	/*
+	 * Hide command line arguments from ps (in particular for
+	 * forked children that don't execv()).  This is an ugly
+	 * hack that only works on Linux.
+	 * https://web.archive.org/web/20110227041321/http://netsplit.com/2007/01/10/hiding-arguments-from-ps/
+	 */
+	if (argc > 1) {
+		char *arg_end;
+
+		arg_end = argv[argc-1] + strlen (argv[argc-1]);
+		*arg_end = ' ';
+	}
+}
+
 static void parse_arg(char *arg, int *dbg)
 {
 	/* Catches finit_debug (deprecated), --debug, and debug */
@@ -84,6 +100,8 @@ void conf_parse_cmdline(int argc, char *argv[])
 	for (int i = 1; i < argc; i++)
 		parse_arg(argv[i], &dbg);
 
+	hide_args(argc, argv);
+
 	fp = fopen("/proc/cmdline", "r");
 	if (!fp)
 		goto done;