Fix #261: support for overriding default runlevel from command line

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

configure.ac

@@ -130,7 +130,7 @@ AC_ARG_WITH(hostname,
 	[hostname=$withval], [hostname=yes])
 
 AC_ARG_WITH(runlevel,
-        AS_HELP_STRING([--with-runlevel=N], [Runlevel to switch to after bootstrap, default: 2]),
+        AS_HELP_STRING([--with-runlevel=N], [Runlevel to switch to after bootstrap [1-9], default: 2]),
 	[runlevel=$withval], [runlevel=yes])
 
 AC_ARG_WITH(random-seed,

doc/cmdline.md

@@ -73,6 +73,12 @@ The `bool` setting is one of `on, off, true false, 1, 0`.
     `[1]` will be started, so a `tty [1] @console nologin` configuration
     presents you with a root console without login.
 
+ * `1-9`, except `6`: override the configured `runlevel`.  Like the `S`
+   and `rescue`, giving a single number on the kernel command line tells
+   Finit to ignore any `runlevel` in `/etc/finit.conf` as well as the
+   configure fallback `--with-runlevel=N` setting.  Remember, `6` is the
+   reboot runlevel and is not permitted.  Any other values are ignored.
+
 For more on kernel boot parameters, see the man page [bootparam(7)][].
 
 [config.md]:    config.md#rescue-mode

src/conf.c

@@ -134,6 +134,33 @@ static void parse_finit_opts(char *opt)
 	}
 }
 
+/*
+ * When runlevel (single integer) is given on the command line,
+ * it overrides the runlevel in finit.conf and the built-in
+ * default (from configure).  It do however have to pass the
+ * same sanity checks.
+ */
+static int parse_runlevel(char *arg)
+{
+	const char *err = NULL;
+	char *ptr = arg;
+	long long num;
+
+	/* Sanity check the token is just digit(s) */
+	while (*ptr) {
+		if (!isdigit(*ptr++))
+			return 0;
+	}
+
+	num = strtonum(arg, 1, 9, &err);
+	if (err || num == 6) {
+		_d("Not a valid runlevel (%s), valid levels are [1-9], excluding 6, skipping.", arg);
+		return 0;
+	}
+
+	return (int)num;
+}
+
 static void parse_arg(char *arg)
 {
 	if (!strncmp(arg, "finit.", 6)) {
@@ -141,11 +168,19 @@ static void parse_arg(char *arg)
 		return;
 	}
 
-	if (string_compare(arg, "rescue") || string_compare(arg, "recover"))
+	if (string_compare(arg, "rescue") || string_compare(arg, "recover")) {
 		rescue = 1;
+		return;
+	}
 
-	if (string_compare(arg, "single") || string_compare(arg, "S"))
+	if (string_compare(arg, "single") || string_compare(arg, "S")) {
 		single = 1;
+		return;
+	}
+
+	/* Put any new command line options before this line. */
+
+	cmdlevel = parse_runlevel(arg);
 }
 
 #ifdef KERNEL_CMDLINE

src/finit.c

@@ -62,6 +62,7 @@
 
 int   runlevel  = 0;		/* Bootstrap 'S' */
 int   cfglevel  = RUNLEVEL;	/* Fallback if no configured runlevel */
+int   cmdlevel  = 0;		/* runlevel override from cmdline */
 int   prevlevel = -1;
 int   debug     = 0;		/* debug mode from kernel cmdline */
 int   rescue    = 0;		/* rescue mode from kernel cmdline */
@@ -569,11 +570,12 @@ static void crank_worker(void *unused)
  */
 static void bootstrap_worker(void *work)
 {
-	static int cnt = 120;
 	static struct wq final = {
 		.cb = finalize,
 		.delay = 10
 	};
+	static int cnt = 120;
+	int level = cfglevel;
 
 	_d("Step all services ...");
 	service_step_all(SVC_TYPE_ANY);
@@ -598,11 +600,18 @@ static void bootstrap_worker(void *work)
 	if (runparts && fisdir(runparts) && !rescue)
 		run_parts(runparts, NULL);
 
+
 	/*
-	 * Start all tasks/services in the configured runlevel
+	 * Start all tasks/services in the configured runlevel, or jump
+	 * into the runlevel selected from the command line.
 	 */
-	_d("Change to default runlevel(%d), starting all services ...", cfglevel);
+	if (cmdlevel) {
-	service_runlevel(cfglevel);
+		_d("Runlevel %d requested from command line, starting all services ...", cmdlevel);
+		level = cmdlevel;
+	} else
+		_d("Change to default runlevel(%d), starting all services ...", cfglevel);
+
+	service_runlevel(level);
 }
 
 static int version(int rc)

src/finit.h

@@ -110,6 +110,7 @@ struct init_request {
 
 extern int    runlevel;
 extern int    cfglevel;
+extern int    cmdlevel;
 extern int    prevlevel;
 extern int    debug;
 extern int    rescue;