Fix #250: support finit.cond=foo for cmdline <boot/foo> conditions

As a real life example, this can be useful for a mfgtest mode for the
device, wherein the bootloader can be set to finit.cond=test_mode or
finit.cond=user_mode and then specific services can start up in test
mode which wouldn't normally start.

Or even custom firmware update mode such as finit.cond=fw_update_mode
which performs some specific firmware update steps and doesn't launch
normal processes.

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

doc/cmdline.md

@@ -12,6 +12,17 @@ The `bool` setting is one of `on, off, true false, 1, 0`.
 * `debug`: Enable kernel debug.  Debug messages are printed to the
    console until Finit starts up, unless `loglevel=7` (below) is used.
 
+* `finit.cond=foo[,bar[,baz]]`: set `<boot/foo>` condition, optionally
+  multiple conditions can be set using the same option, separated with a
+  comma.  Alternatively, multiple `foo.cond=arg` can be given.  Each will
+  result in a `<boot/arg>` condition being set to control the rest of the
+  system bootstrap.
+
+  Very useful for selecting different boot modes, e.g. manufacturing test,
+  firmware upgrade, or rescue mode.
+
+  > Note: `<boot/...>` conditions cannot be cleared with `initctl`!
+
 * `finit.debug[=bool]`: Enable finit debug.  This is operated
 	independently of the kernel `debug` setting.  New as of Finit v4.
 

doc/conditions.md

@@ -46,11 +46,16 @@ Triggering
 ----------
 
 Conditions are mainly triggered (asserted) by built-in plugins, e.g.,
-`netlink.so` and `pidfile.so`, see below for built-in conditions.  Finit
-also supports user-defined conditions, sometimes referred to as static
-or one-shot conditions.  They live in the `<usr/...` namespace and are
-constrained to a flat hierarchy without any sub-directories, unlike the
-pidfile plugin, for instance.
+
+  - `netlink.so`: provides `<net/...>`
+  - `pidfile.so`: provides `<pid/...>`
+  - Cmdline `finit.cond=arg`: provides `<boot/arg`
+
+See below for built-in conditions.  Finit also supports user-defined
+conditions, sometimes referred to as static or one-shot conditions.
+They live in the `<usr/...` namespace and are constrained to a flat
+hierarchy without any sub-directories, unlike the pidfile plugin, for
+instance.
 
 User-defined conditions are controlled using the `initctl cond set` and
 `initctl cond clear` commands:
@@ -118,6 +123,7 @@ Built-in conditions:
 - `sys/pwr/fail`
 - `sys/key/ctrlaltdel`
 - `usr/foo`
+- `boot/arg`
 
 **Note:** `up` means administratively up, the interface flag `IFF_UP`.
   `running` is the `IFF_RUNNING` flag, meaning operatively up.  The

src/cond-w.c

@@ -36,6 +36,67 @@
 #include "pid.h"
 #include "service.h"
 
+struct cond_boot {
+	TAILQ_ENTRY(cond_boot) link;
+	char *name;
+};
+static TAILQ_HEAD(, cond_boot) cond_boot_list = TAILQ_HEAD_INITIALIZER(cond_boot_list);
+
+
+/*
+ * Parse finit.cond=cond[,cond[,...]] from command line.  It creates a
+ * temporary linked list of conds which are freed when finit reaches
+ * cond_init(), which calls cond_boot_strap() to realize the conditions
+ * in the file system as regular static conditions.  Policy, however,
+ * dictates that these are read-only and should not be possible to
+ * manage from initctl.
+ */
+void cond_boot_parse(char *arg)
+{
+	struct cond_boot *node;
+
+	if (!arg)
+		return;
+
+	node = malloc(sizeof(*node));
+	if (!node) {
+		_pe("Out of memory cannot track boot conditions");
+		return;
+	}
+
+	node->name = strdup(arg);
+	TAILQ_INSERT_HEAD(&cond_boot_list, node, link);
+}
+
+/*
+ * Convert all conditions read from the kernel command line (above) into
+ * proper finit conditions.
+ */
+static void cond_boot_strap(void)
+{
+	struct cond_boot *node, *tmp;
+
+	TAILQ_FOREACH_SAFE(node, &cond_boot_list, link, tmp) {
+		TAILQ_REMOVE(&cond_boot_list, node, link);
+		if (node->name) {
+			char *ptr;
+
+			ptr = strtok(node->name, ",");
+			while (ptr) {
+				char cond[strlen(ptr) + 6];
+
+				snprintf(cond, sizeof(cond), "boot/%s", ptr);
+				cond_set_oneshot_noupdate(cond);
+
+				ptr = strtok(NULL, ",");
+			}
+
+			free(node->name);
+		}
+		free(node);
+	}
+}
+
 /*
  * The service condition name is constructed from the 'pid/' prefix and
  * the unique NAME:ID tuple that identify each process in Finit.  Here
@@ -366,6 +427,7 @@ void cond_init(void)
 	}
 
 	cond_bump_reconf();
+	cond_boot_strap();
 }
 
 /**

src/cond.h

@@ -31,6 +31,7 @@ enum cond_state cond_get     (const char *name);
 enum cond_state cond_get_agg (const char *names);
 int             cond_affects (const char *name, const char *names);
 
+void cond_boot_parse  (char *arg);
 int  cond_update      (const char *name);
 int  cond_set_path    (const char *path, enum cond_state new);
 void cond_set         (const char *name);
@@ -38,9 +39,9 @@ void cond_set_oneshot (const char *name);
 void cond_clear       (const char *name);
 void cond_reload      (void);
 
-int cond_set_noupdate (const char *name);
-int cond_set_oneshot_noupdate(const char *name);
-int cond_clear_noupdate(const char *name);
+int  cond_set_noupdate(const char *name);
+int  cond_set_oneshot_noupdate(const char *name);
+int  cond_clear_noupdate(const char *name);
 
 void cond_reassert    (const char *pat);
 void cond_deassert    (const char *pat);

src/conf.c

@@ -113,6 +113,11 @@ static void parse_finit_opts(char *opt)
 		return;
 	}
 
+	if (string_compare(opt, "cond")) {
+		cond_boot_parse(arg);
+		return;
+	}
+
 	if (string_compare(opt, "status_style")) {
 		if (!arg) {
 			_e("status_style option requires an argument, skipping.");