Android init源代碼分析（2）init.rc解析

    INFO("reading config file\n");
    init_parse_config_file("/init.rc")

static list_declare(service_list);
static list_declare(action_list);
static list_declare(action_queue);

struct command
{
        /* list of commands in an action */
    struct listnode clist;

    int (*func)(int nargs, char **args);

    int line;
    const char *filename;

    int nargs;
    char *args[1];
};

struct action {
        /* node in list of all actions */
    struct listnode alist;
        /* node in the queue of pending actions */
    struct listnode qlist;
        /* node in list of actions for a trigger */
    struct listnode tlist;

    unsigned hash;
    const char *name;

    struct listnode commands;
    struct command *current;
};

struct service {
        /* list of all services */
    struct listnode slist; //用於掛載於service_list的鉤子
    const char *name; //存放service的名稱
    const char *classname; //用於存放該service所隸屬的class的名稱
    unsigned flags; //位圖變量，其各個位代表不同的servcie的屬性（對應service中的option字段）
    pid_t pid; //當service對應的程序執行時，存放其進程號
    time_t time_started;    /* time of last start */ //存放進程啟動時間
    time_t time_crashed;    /* first crash within inspection window */ //存放第一次進程崩潰時間
    int nr_crashed;         /* number of times crashed within window */ //存放進程崩潰次數
    
    uid_t uid; //該servcie對應進程的uid
    gid_t gid; //該service對應進程的gidinit_parse_config_file("/init.rc");
    gid_t supp_gids[NR_SVC_SUPP_GIDS];//該service對應進程的附加群組id
    size_t nr_supp_gids; //該service所隸屬的附件組的數目
    char *seclabel; //存放selinux所需要的security context
    struct socketinfo *sockets;    struct svcenvinfo *envvars;

    struct action onrestart;  /* Actions to execute on restart. */
    
    /* keycodes for triggering this service via /dev/keychord */
    int *keycodes;"queue_property_triggers"
    int nkeycodes;
    int keychord_id;

    int ioprio_class;
    int ioprio_pri;
    int nargs; //對應service語句傳入的參數數目
    /* "MUST BE AT THE END OF THE STRUCT" */
    char *args[1]; //存放service語句實際傳入的參數，其長度將會被修正為nargs+1
}; /*     ^-------'args' MUST be at the end of this struct! */

service servicemanager /system/bin/servicemanager
    class core
    user system
    group system
    critical
    onrestart restart healthd
    onrestart restart zygote
    onrestart restart media
    onrestart restart surfaceflinger
    onrestart restart drm

//init.h
#define SVC_DISABLED    0x01  /* do not autostart with class */
#define SVC_ONESHOT     0x02  /* do not restart on exit */
#define SVC_RUNNING     0x04  /* currently active */
#define SVC_RESTARTING  0x08  /* waiting to restart */
#define SVC_CONSOLE     0x10  /* requires console */
#define SVC_CRITICAL    0x20  /* will reboot into recovery if keeps crashing */
#define SVC_RESET       0x40  /* Use when stopping a process, but not disabling
                                 so it can be restarted with its class */
#define SVC_RC_DISABLED 0x80  /* Remember if the disabled flag was set in the rc script */
#define SVC_RESTART     0x100 /* Use to safely restart (stop, wait, start) a service */
#define SVC_DISABLED_START 0x200 /* a start was requested but it was disabled at the time */

    action_for_each_trigger("early-init", action_add_queue_tail);

    queue_builtin_action(wait_for_coldboot_done_action, "wait_for_coldboot_done");
    queue_builtin_action(mix_hwrng_into_linux_rng_action, "mix_hwrng_into_lin一部分在ux_rng");
    queue_builtin_action(keychord_init_action, "keychord_init");
    queue_builtin_action(console_init_action, "console_init");

    /* execute all the boot actions to get us started */
    action_for_each_trigger("init", action_add_queue_tail);

    /* skip mounting filesystems in charger mode */
    if (!is_charger) {
        action_for_each_trigger("early-fs", action_add_queue_tail);
        action_for_each_trigger("fs", action_add_queue_tail);
        action_for_each_trigger("post-fs", action_add_queue_tail);
        action_for_each_trigger("post-fs-data", 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");

    queue_builtin_action(property_service_init_action, "property_service_init");
    queue_builtin_action(signal_init_action, "signal_init");
    queue_builtin_action(check_startup_action, "check_startup");

    if (is_charger) {
        action_for_each_trigger("charger", action_add_queue_tail);
    } else {
        action_for_each_trigger("early-boot", action_add_queue_tail);
        action_for_each_trigger("boot", 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");


#if BOOTCHART
    queue_builtin_action(bootchart_init_action, "bootchart_init");
#endif

    for(;;) {
        execute_one_command();
        ...
    }

on late-init
    trigger early-fs
    trigger fs
    trigger post-fs
    trigger post-fs-data

    # Load properties from /system/ + /factory after fs mount. Place
    # this in another action so that the load will be scheduled after the prior
    # issued fs triggers have completed.
    trigger load_all_props_action

    # Remove a file to wake up anything waiting for firmware.
    trigger firmware_mounts_complete

    trigger early-boot
    trigger boot

//keyword.h
//-------------
    KEYWORD(trigger,     COMMAND, 1, do_trigger)
//builtins.c
//-------------
int do_trigger(int nargs, char **args)
{
    action_for_each_trigger(args[1], action_add_queue_tail);
    return 0;
}

static int queue_property_triggers_action(int nargs, char **args)
{
    queue_all_property_triggers();
    /* enable property triggers */
    property_triggers_enabled = 1;
    return 0;
}
void queue_all_property_triggers()
{
    struct listnode *node;
    struct action *act;
    list_for_each(node, &action_list) {
        act = node_to_item(node, struct action, alist);
        if (!strncmp(act->name, "property:", strlen("property:"))) {
            /* parse property name and value
               syntax is property:= */
            const char* name = act->name + strlen("property:");
            const char* equals = strchr(name, '=');
            if (equals) {
                char prop_name[PROP_NAME_MAX + 1];
                char value[PROP_VALUE_MAX];新浪微博
                int length = equals - name;
                if (length > PROP_NAME_MAX) {
                    ERROR("property name too long in trigger %s", act->name);
                } else {
                    int ret;
                    memcpy(prop_name, name, length);
                    prop_name[length] = 0;

                    /* does the property exist, and match the trigger value? */
                    ret = property_get(prop_name, value);
                    if (ret > 0 && (!strcmp(equals + 1, value) ||
                                    !strcmp(equals + 1, "*"))) {
                        action_add_queue_tail(act);
                    }
                }
            }
        }
    }
}

int main(int argc, char* argv[])
{
    ....
    for(;;) {
        execute_one_command();
        ....
        nr = poll(ufds, fd_count, timeout);
        if (nr <= 0)
            continue;
        for (i = 0; i < fd_count; i++) {
            if (ufds[i].revents == POLLIN) {這部分內容請閱讀
                if (ufds[i].fd == get_property_set_fd())
                    handle_property_set_fd();
                ...
            }
        }
    }
}