int main(int argc, char **argv)//内核发生热插拔时会执行一次/proc/sys/kernel/hotplug。
{///sbin/mdev > /proc/sys/kernel/hotplug，本质上内核发生一次热插拔时执行一次/sbin/mdev
int ch;
char *dbglvl = getenv("DBGLVL");
if (dbglvl) {
debug = atoi(dbglvl);
unsetenv("DBGLVL");
}
while ((ch = getopt(argc, argv, "d:s:h:")) != -1) {
switch (ch) {
case 'h':
return hotplug_run(optarg);//执行hotplug_run(/etc/hotplug-preinit.json):
case 's':
ubus_socket = optarg;
break;
case 'd':
debug = atoi(optarg);
break;
default:
return usage(argv[0]);
}
}
uloop_init();
procd_signal();
trigger_init();
if (getpid() != 1)
procd_connect_ubus();
else
procd_state_next();//进程pid=1才执行procd_state_next，这才是开机启动流程中的procd，负责解析/etc/inittab文件并据此依次启动系统。
uloop_run();
return 0;
}
static void rcdone(struct runqueue *q)
{
procd_state_next();
}
static void coldplug_complete(struct uloop_timeout *t)
{
DEBUG(4, "Coldplug complete\n");
hotplug_last_event(NULL);
procd_state_next();
}
static void set_console(void)
{
const char* tty;
char* split;
char line[ 20 ];
const char* try[] = { "tty0", "console", NULL }; /* Try the most common outputs */
int f, i = 0;
tty = get_cmdline_val("console",line,sizeof(line));
if (tty != NULL) {
split = strchr(tty, ',');
if ( split != NULL )
*split = '\0';
} else {
// Try a default
tty=try[i];
i++;
}
if (chdir("/dev")) {
ERROR("failed to change dir to /dev\n");
return;
}
while (tty!=NULL) {
f = open(tty, O_RDONLY);
if (f >= 0) {
close(f);
break;
}
tty=try[i];
i++;
}
if (chdir("/"))
ERROR("failed to change dir to /\n");
if (tty != NULL)
set_stdio(tty);
}
static void state_enter(void)
{
char ubus_cmd[] = "/sbin/ubusd";
switch (state) {
case STATE_EARLY:
LOG("- early -\n");
watchdog_init(0);
hotplug("/etc/hotplug.json");
procd_coldplug();
break;
case STATE_UBUS:
// try to reopen incase the wdt was not available before coldplug
watchdog_init(0);
set_stdio("console");
LOG("- ubus -\n");
procd_connect_ubus();
service_start_early("ubus", ubus_cmd);
break;
case STATE_INIT:
LOG("- init -\n");
procd_inittab();
procd_inittab_run("respawn");
procd_inittab_run("askconsole");
procd_inittab_run("askfirst");
procd_inittab_run("sysinit");
// switch to syslog log channel
ulog_open(ULOG_SYSLOG, LOG_DAEMON, "procd");
break;
case STATE_RUNNING:
LOG("- init complete -\n");
break;
case STATE_SHUTDOWN:
/* Redirect output to the console for the users' benefit */
set_console();
LOG("- shutdown -\n");
procd_inittab_run("shutdown");
sync();
break;
case STATE_HALT:
// To prevent killed processes from interrupting the sleep
signal(SIGCHLD, SIG_IGN);
LOG("- SIGTERM processes -\n");
kill(-1, SIGTERM);
sync();
sleep(1);
LOG("- SIGKILL processes -\n");
kill(-1, SIGKILL);
sync();
sleep(1);
#ifndef DISABLE_INIT
if (reboot_event == RB_POWER_OFF)
LOG("- power down -\n");
else
LOG("- reboot -\n");
/* Allow time for last message to reach serial console, etc */
sleep(1);
/* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS)
* in linux/kernel/sys.c, which can cause the machine to panic when
* the init process exits... */
if (!vfork( )) { /* child */
reboot(reboot_event);
_exit(EXIT_SUCCESS);
}
while (1)
sleep(1);
#else
exit(0);
#endif
break;
default:
ERROR("Unhandled state %d\n", state);
return;
};
}
void procd_state_next(void)
{
DEBUG(4, "Change state %d -> %d\n", state, state + 1);
state++;
state_enter();
}
void procd_state_ubus_connect(void)
{
if (state == STATE_UBUS)
procd_state_next();
}
void procd_shutdown(int event)
{
if (state >= STATE_SHUTDOWN)
return;
DEBUG(2, "Shutting down system with event %x\n", event);
reboot_event = event;
state = STATE_SHUTDOWN;
state_enter();
}
