struct service {

void NotifyStateChange(const char* new_state);

/* list of all services */

struct listnode slist;

char *name;

const char *classname;

unsigned flags;

pid_t pid;

time_t time_started;    /* time of last start */

time_t time_crashed;    /* first crash within inspection window */

int nr_crashed;         /* number of times crashed within window */

uid_t uid;

gid_t gid;

gid_t supp_gids[NR_SVC_SUPP_GIDS];

size_t nr_supp_gids;

const char* seclabel;

struct socketinfo *sockets;

struct svcenvinfo *envvars;

struct action onrestart;  /* Actions to execute on restart. */

std::vector<std::string>* writepid_files_;

/* keycodes for triggering this service via /dev/keychord */

int *keycodes;

int nkeycodes;

int keychord_id;

IoSchedClass ioprio_class;

int ioprio_pri;

int nargs;

/* "MUST BE AT THE END OF THE STRUCT" */

char *args[1];

};

int main(int argc, char** argv) {

if (!strcmp(basename(argv[0]), "ueventd")) {

return ueventd_main(argc, argv);

}

if (!strcmp(basename(argv[0]), "watchdogd")) {

return watchdogd_main(argc, argv);

}

// Clear the umask.

umask(0);

add_environment("PATH", _PATH_DEFPATH);

bool is_first_stage = (argc == 1) || (strcmp(argv[1], "--second-stage") != 0);

// Get the basic filesystem setup we need put together in the initramdisk

// on / and then we'll let the rc file figure out the rest.

if (is_first_stage) {

mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755");

mkdir("/dev/pts", 0755);

mkdir("/dev/socket", 0755);

mount("devpts", "/dev/pts", "devpts", 0, NULL);

mount("proc", "/proc", "proc", 0, NULL);

mount("sysfs", "/sys", "sysfs", 0, NULL);

}

// We must have some place other than / to create the device nodes for

// kmsg and null, otherwise we won't be able to remount / read-only

// later on. Now that tmpfs is mounted on /dev, we can actually talk

// to the outside world.

open_devnull_stdio();

klog_init();

klog_set_level(KLOG_NOTICE_LEVEL);

NOTICE("init%s started!\n", is_first_stage ? "" : " second stage");

if (!is_first_stage) {

// Indicate that booting is in progress to background fw loaders, etc.

close(open("/dev/.booting", O_WRONLY | O_CREAT | O_CLOEXEC, 0000));

property_init();

// If arguments are passed both on the command line and in DT,

// properties set in DT always have priority over the command-line ones.

process_kernel_dt();

process_kernel_cmdline();

// Propogate the kernel variables to internal variables

// used by init as well as the current required properties.

export_kernel_boot_props();

}

// Set up SELinux, including loading the SELinux policy if we're in the kernel domain.

selinux_initialize(is_first_stage);

// If we're in the kernel domain, re-exec init to transition to the init domain now

// that the SELinux policy has been loaded.

if (is_first_stage) {

if (restorecon("/init") == -1) {

ERROR("restorecon failed: %s\n", strerror(errno));

security_failure();

}

char* path = argv[0];

char* args[] = { path, const_cast<char*>("--second-stage"), nullptr };

if (execv(path, args) == -1) {

ERROR("execv(\"%s\") failed: %s\n", path, strerror(errno));

security_failure();

}

}

// These directories were necessarily created before initial policy load

// and therefore need their security context restored to the proper value.

// This must happen before /dev is populated by ueventd.

INFO("Running restorecon...\n");

restorecon("/dev");

restorecon("/dev/socket");

restorecon("/dev/__properties__");

restorecon_recursive("/sys");

epoll_fd = epoll_create1(EPOLL_CLOEXEC);

if (epoll_fd == -1) {

ERROR("epoll_create1 failed: %s\n", strerror(errno));

exit(1);

}

signal_handler_init();

property_load_boot_defaults();

start_property_service();

init_parse_config_file("/init.rc");

action_for_each_trigger("early-init", action_add_queue_tail);

// Queue an action that waits for coldboot done so we know ueventd has set up all of /dev...

queue_builtin_action(wait_for_coldboot_done_action, "wait_for_coldboot_done");

// ... so that we can start queuing up actions that require stuff from /dev.

queue_builtin_action(mix_hwrng_into_linux_rng_action, "mix_hwrng_into_linux_rng");

queue_builtin_action(keychord_init_action, "keychord_init");

queue_builtin_action(console_init_action, "console_init");

// Trigger all the boot actions to get us started.

action_for_each_trigger("init", action_add_queue_tail);

// Repeat mix_hwrng_into_linux_rng in case /dev/hw_random or /dev/random

// wasn't ready immediately after wait_for_coldboot_done

queue_builtin_action(mix_hwrng_into_linux_rng_action, "mix_hwrng_into_linux_rng");

// Don't mount filesystems or start core system services in charger mode.

char bootmode[PROP_VALUE_MAX];

if (property_get("ro.bootmode", bootmode) > 0 && strcmp(bootmode, "charger") == 0) {

action_for_each_trigger("charger", action_add_queue_tail);

} else {

action_for_each_trigger("late-init", action_add_queue_tail);

}

// Run all property triggers based on current state of the properties.

queue_builtin_action(queue_property_triggers_action, "queue_property_triggers");

while (true) {

if (!waiting_for_exec) {

execute_one_command();

restart_processes();

}

int timeout = -1;

if (process_needs_restart) {

timeout = (process_needs_restart - gettime()) * 1000;

if (timeout < 0)

timeout = 0;

}

if (!action_queue_empty() || cur_action) {

timeout = 0;

}

bootchart_sample(&timeout);

epoll_event ev;

int nr = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd, &ev, 1, timeout));

if (nr == -1) {

ERROR("epoll_wait failed: %s\n", strerror(errno));

} else if (nr == 1) {

((void (*)()) ev.data.ptr)();//其实最根本的改变在这，为了封装

}

}

return 0;

}

//App_main.main()中

if (zygote) {

runtime.start("com.android.internal.os.ZygoteInit", args, zygote);

} else if (className) {

runtime.start("com.android.internal.os.RuntimeInit", args, zygote);

} else {

fprintf(stderr, "Error: no class name or --zygote supplied.\n");

app_usage();

LOG_ALWAYS_FATAL("app_process: no class name or --zygote supplied.");

return 10;

}