Support delayed load of services from plugins and bundled services

This adds a new function conf_save_service() replacing service_register() for
plugins and bundled services like watchdogd, keventd, runparts, etc.

The benefits to this change are several:

 - Plugin/Bundled services no longer risk starting before udev or other
   critical services/task have started
 - Definitions can be overridden by an administrator (see docs)
 - Increases visibility (user: where are all these services coming from?)
   Previously the origin (file the service was loaded from) was NULL.
 - Adds another level of extensibility to Finit

The most notable change is that dbus is no longer started before udevd.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

configure.ac

@@ -298,6 +298,7 @@ pkglibdir=$libdir/finit
 AC_SUBST(pkglibexecdir)
 AC_EXPAND_DIR(pkglibexecdir, "$libexecdir/finit")
 AC_DEFINE_UNQUOTED(FINIT_EXECPATH_, "$pkglibexecdir", [Finit libexec path])
+AC_DEFINE_UNQUOTED(FINIT_RUNPATH_, "/run/finit/system", [Finit runtime dynamic system services])
 
 AC_EXPAND_DIR(plugin_path, "$pkglibdir/plugins")
 AC_SUBST(plugin_path)
@@ -313,7 +314,7 @@ AC_DEFINE_UNQUOTED(FINIT_TMPFILES, "$finit_tmpfiles", [Finit tmpfiles.d/ .conf p
 
 AC_EXPAND_DIR(system_path, "$pkglibdir/system")
 AC_SUBST(system_path)
-AC_DEFINE_UNQUOTED(FINIT_SYSPATH, "$system_path", [Static services, previously generated at runtime by plugins])
+AC_DEFINE_UNQUOTED(FINIT_SYSPATH_, "$system_path", [Static services, previously generated at runtime by plugins])
 
 AC_EXPAND_DIR(rescue_conf, "$pkglibdir/rescue.conf")
 AC_DEFINE_UNQUOTED(RESCUE_CONF, "$rescue_conf", [Finit rescue mode .conf])

doc/config.md

@@ -68,10 +68,18 @@ the following layout is recommended:
     |  :   `- another-static.conf
     |  :
     |  `- finit.conf
-    `- lib/
+    |- lib
+    |   `- finit/
+    |       `- system/
+    |           |- 10-hotplug.conf
+    |           `- ...
+    `- run/
         `- finit/
             `- system/
-                |- 10-hotplug.conf
+                |- dbus.conf
+                |- keventd.conf
+                |- runparts.conf
+                |- watchdogd.conf
                 `- ...
 
 Configuration files in `/etc` are provided by the user, or projects like
@@ -85,6 +93,11 @@ the hard-coded services provided by plugins before.  All .conf files in this
 directory be either replaced by a system administrator or overridden by a
 file with the same name in `/etc/finit.d/`.
 
+The files in `/run/finit/system/*.conf` are created by plugins and Finit
+bundled services like runparts, the [watchdog](#watchdog), and `keventd`
+if they are enabled.  Like `/lib/finit/system/*.conf`, these files can
+ be overridden by file with the same name in `/etc/finit.d/`.
+
 Services in the `available/` and `enabled/` sub-directories are called
 dynamic services, in contrast to static services -- the only difference
 being where they are installed and if the `initctl` tool can manage them
@@ -100,6 +113,8 @@ unique group, where files within each group are sorted alphabetically.
 
     /lib/finit/system/10-hotplug.conf
     /lib/finit/system/90-testserv.conf
+    /run/finit/system/dbus.conf
+    /run/finit/system/runparts.conf
     /etc/finit.d/10-abc.conf
     /etc/finit.d/20-abc.conf
     /etc/finit.d/enabled/1-aaa.conf

plugins/dbus.c

@@ -157,9 +157,7 @@ static void setup(void *arg)
 		snprintf(line, sizeof(line), "[S123456789] cgroup.system name:dbus %s %s -- %s",
 			 cmd, DBUS_ARGS, DBUS_DESC);
 
-	if (service_register(SVC_TYPE_SERVICE, line, global_rlimit, NULL))
+	conf_save_service(SVC_TYPE_SERVICE, line, "dbus.conf");
-		err(1, "Failed registering %s", DBUS_DAEMON);
-
 	free(cmd);
 }
 

src/conf.c

@@ -462,6 +462,30 @@ void conf_save_exec_order(svc_t *svc, char *cmdline, int result)
 	fclose(fp);
 }
 
+/*
+ * Called by plugins and similar that dynamically generate system services
+ */
+void conf_save_service(int type, char *cfg, char *file)
+{
+	char fn[256];
+	svc_t foo;
+	FILE *fp;
+
+	snprintf(fn, sizeof(fn), "%s/%s", FINIT_RUNPATH_, file);
+	if (fexist(fn))
+		warn("File %s already exists, overwriting.", fn);
+	fp = fopen(fn, "w");
+	if (!fp) {
+		err(1, "Failed creating %s", fn);
+		return;
+	}
+
+	foo.type = type;
+	fprintf(fp, "# Generated by finit:%s()\n", __func__);
+	fprintf(fp, "%s %s\n", svc_typestr(&foo), cfg);
+	fclose(fp);
+}
+
 /*
  * Sets, and makes a note of, all KEY=VALUE lines in a given .conf line
  * from finit.conf, or other .conf file.  Note, PATH is always reset in
@@ -1207,13 +1231,16 @@ int conf_reload(void)
 	 *
 	 *     /lib/finit/system/10-hotplug.conf
 	 *     /lib/finit/system/90-testserv.conf
+	 *     /run/finit/system/dbus.conf
+	 *     /run/finit/system/tty.conf
 	 *     /etc/finit.d/10-abc.conf
 	 *     /etc/finit.d/20-abc.conf
 	 *     /etc/finit.d/enabled/1-aaa.conf
 	 *     /etc/finit.d/enabled/1-abc.conf
 	 *     /etc/finit.d/enabled/2-aaa.conf
 	 */
-	glob_append(&gl, 0, "%s/*.conf", FINIT_SYSPATH);
+	glob_append(&gl, 0, "%s/*.conf", FINIT_SYSPATH_);
+	glob_append(&gl, 1, "%s/*.conf", FINIT_RUNPATH_);
 	glob_append(&gl, 1, "%s/*.conf", finit_rcsd);
 	glob_append(&gl, 1, "%s/enabled/*.conf", finit_rcsd);
 
@@ -1238,9 +1265,10 @@ int conf_reload(void)
 		struct stat st;
 		size_t j, len;
 
-		/* check for FINIT_SYSPATH overrides */
+		/* check for FINIT_SYSPATH_ or FINIT_RUNPATH_ overrides */
 		for (j = i + 1; j < gl.gl_pathc; j++) {
-			if (strncmp(path, FINIT_SYSPATH, strlen(FINIT_SYSPATH)))
+			if (strncmp(path, FINIT_SYSPATH_, strlen(FINIT_SYSPATH_)) &&
+			    strncmp(path, FINIT_RUNPATH_, strlen(FINIT_RUNPATH_)))
 				continue;
 			if (strcmp(basename(path), basename(gl.gl_pathv[j])))
 				continue;
@@ -1300,6 +1328,9 @@ done:
 	/* Drop record of all .conf changes */
 	drop_changes();
 
+	if (bootstrap)
+		wdog = svc_find("watchdog", "finit");
+
 	/* Override configured runlevel, user said 'S' on /proc/cmdline */
 	if (BOOTSTRAP && single)
 		cfglevel = 1;
@@ -1536,15 +1567,16 @@ int conf_init(uev_ctx_t *ctx)
 	 */
 #ifdef WDT_DEVNODE
 	if (whichp(FINIT_EXECPATH_ "/watchdogd") && fexist(WDT_DEVNODE)) {
-		service_register(SVC_TYPE_SERVICE, "[S0123456789] cgroup.init name:watchdog :finit " FINIT_EXECPATH_ "/watchdogd -- Finit watchdog daemon", global_rlimit, NULL);
+		conf_save_service(SVC_TYPE_SERVICE, "[S0123456789] cgroup.init name:watchdog :finit "
-		wdog = svc_find("watchdog", "finit");
+				  FINIT_EXECPATH_ "/watchdogd -- Finit watchdog daemon", "watchdogd.conf");
 	}
 #endif
 	/*
 	 * Start kernel event daemon as soon as possible, if enabled
 	 */
 	if (whichp(FINIT_EXECPATH_ "/keventd"))
-		service_register(SVC_TYPE_SERVICE, "[S0123456789] cgroup.init " FINIT_EXECPATH_ "/keventd -- Finit kernel event daemon", global_rlimit, NULL);
+		conf_save_service(SVC_TYPE_SERVICE, "[S0123456789] cgroup.init "
+				  FINIT_EXECPATH_ "/keventd -- Finit kernel event daemon", "keventd.conf");
 
 	dbg("Allow plugins to register early runlevel 1 run/task/services ...");
 	plugin_run_hooks(HOOK_SVC_PLUGIN);
@@ -1580,7 +1612,7 @@ int conf_init(uev_ctx_t *ctx)
 		snprintf(conf, sizeof(conf), "[S] <int/bootstrap> log:console %s %s %s"
 			 " -- Calling runparts %s in the background",
 			 _PATH_RUNPARTS, args, runparts, runparts);
-		service_register(SVC_TYPE_TASK, conf, global_rlimit, NULL);
+		conf_save_service(SVC_TYPE_TASK, conf, "runparts.conf");
 	}
 
 	return 0;

src/conf.h

@@ -45,6 +45,7 @@ int  conf_monitor         (void);
 void conf_reset_env       (void);
 void conf_saverc          (void);
 void conf_save_exec_order (svc_t *svc, char *cmdline, int result);
+void conf_save_service    (int type, char *cfg, char *file);
 void conf_parse_cmdline   (int argc, char *argv[]);
 int  conf_parse_runlevels (char *runlevels);
 void conf_parse_cond      (svc_t *svc, char *cond);

tmpfiles.d/finit.conf

@@ -11,4 +11,4 @@ d  /run/finit/cond	0755 - - -
 d  /run/finit/cond/pid	0755 - - -
 d  /run/finit/cond/sys	0755 - - -
 d  /run/finit/cond/usr	0755 - - -
-
+d  /run/finit/system	0755 - - -