init/init.cpp

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <paths.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <termios.h>
#include <unistd.h>

#include <mtd/mtd-user.h>

#include <selinux/selinux.h>
#include <selinux/label.h>
#include <selinux/android.h>

#include <base/file.h>
#include <base/stringprintf.h>
#include <cutils/android_reboot.h>
#include <cutils/fs.h>
#include <cutils/iosched_policy.h>
#include <cutils/list.h>
#include <cutils/sockets.h>
#include <private/android_filesystem_config.h>

#include <memory>

#include "devices.h"
#include "init.h"
#include "log.h"
#include "property_service.h"
#include "bootchart.h"
#include "signal_handler.h"
#include "keychords.h"
#include "init_parser.h"
#include "util.h"
#include "ueventd.h"
#include "watchdogd.h"

struct selabel_handle *sehandle;
struct selabel_handle *sehandle_prop;

static int property_triggers_enabled = 0;

static char qemu[32];

static struct action *cur_action = NULL;
static struct command *cur_command = NULL;

static int have_console;
static char console_name[PROP_VALUE_MAX] = "/dev/console";
static time_t process_needs_restart;

static const char *ENV[32];

bool waiting_for_exec = false;

void service::NotifyStateChange(const char* new_state) {
    if (!properties_initialized()) {
        // If properties aren't available yet, we can't set them.
        return;
    }

    if ((flags & SVC_EXEC) != 0) {
        // 'exec' commands don't have properties tracking their state.
        return;
    }

    char prop_name[PROP_NAME_MAX];
    if (snprintf(prop_name, sizeof(prop_name), "init.svc.%s", name) >= PROP_NAME_MAX) {
        // If the property name would be too long, we can't set it.
        ERROR("Property name \"init.svc.%s\" too long; not setting to %s\n", name, new_state);
        return;
    }

    property_set(prop_name, new_state);
}

/* add_environment - add "key=value" to the current environment */
int add_environment(const char *key, const char *val)
{
    size_t n;
    size_t key_len = strlen(key);

    /* The last environment entry is reserved to terminate the list */
    for (n = 0; n < (ARRAY_SIZE(ENV) - 1); n++) {

        /* Delete any existing entry for this key */
        if (ENV[n] != NULL) {
            size_t entry_key_len = strcspn(ENV[n], "=");
            if ((entry_key_len == key_len) && (strncmp(ENV[n], key, entry_key_len) == 0)) {
                free((char*)ENV[n]);
                ENV[n] = NULL;
            }
        }

        /* Add entry if a free slot is available */
        if (ENV[n] == NULL) {
            char* entry;
            asprintf(&entry, "%s=%s", key, val);
            ENV[n] = entry;
            return 0;
        }
    }

    ERROR("No env. room to store: '%s':'%s'\n", key, val);

    return -1;
}

void zap_stdio(void)
{
    int fd;
    fd = open("/dev/null", O_RDWR);
    dup2(fd, 0);
    dup2(fd, 1);
    dup2(fd, 2);
    close(fd);
}

static void open_console()
{
    int fd;
    if ((fd = open(console_name, O_RDWR)) < 0) {
        fd = open("/dev/null", O_RDWR);
    }
    ioctl(fd, TIOCSCTTY, 0);
    dup2(fd, 0);
    dup2(fd, 1);
    dup2(fd, 2);
    close(fd);
}

static void publish_socket(const char *name, int fd)
{
    char key[64] = ANDROID_SOCKET_ENV_PREFIX;
    char val[64];

    strlcpy(key + sizeof(ANDROID_SOCKET_ENV_PREFIX) - 1,
            name,
            sizeof(key) - sizeof(ANDROID_SOCKET_ENV_PREFIX));
    snprintf(val, sizeof(val), "%d", fd);
    add_environment(key, val);

    /* make sure we don't close-on-exec */
    fcntl(fd, F_SETFD, 0);
}

void service_start(struct service *svc, const char *dynamic_args)
{
    // Starting a service removes it from the disabled or reset state and
    // immediately takes it out of the restarting state if it was in there.
    svc->flags &= (~(SVC_DISABLED|SVC_RESTARTING|SVC_RESET|SVC_RESTART|SVC_DISABLED_START));
    svc->time_started = 0;

    // Running processes require no additional work --- if they're in the
    // process of exiting, we've ensured that they will immediately restart
    // on exit, unless they are ONESHOT.
    if (svc->flags & SVC_RUNNING) {
        return;
    }

    bool needs_console = (svc->flags & SVC_CONSOLE);
    if (needs_console && !have_console) {
        ERROR("service '%s' requires console\n", svc->name);
        svc->flags |= SVC_DISABLED;
        return;
    }

    struct stat s;
    if (stat(svc->args[0], &s) != 0) {
        ERROR("cannot find '%s', disabling '%s'\n", svc->args[0], svc->name);
        svc->flags |= SVC_DISABLED;
        return;
    }

    if ((!(svc->flags & SVC_ONESHOT)) && dynamic_args) {
        ERROR("service '%s' must be one-shot to use dynamic args, disabling\n",
               svc->args[0]);
        svc->flags |= SVC_DISABLED;
        return;
    }

    char* scon = NULL;
    if (is_selinux_enabled() > 0) {
        if (svc->seclabel) {
            scon = strdup(svc->seclabel);
            if (!scon) {
                ERROR("Out of memory while starting '%s'\n", svc->name);
                return;
            }
        } else {
            char *mycon = NULL, *fcon = NULL;

            INFO("computing context for service '%s'\n", svc->args[0]);
            int rc = getcon(&mycon);
            if (rc < 0) {
                ERROR("could not get context while starting '%s'\n", svc->name);
                return;
            }

            rc = getfilecon(svc->args[0], &fcon);
            if (rc < 0) {
                ERROR("could not get context while starting '%s'\n", svc->name);
                freecon(mycon);
                return;
            }

            rc = security_compute_create(mycon, fcon, string_to_security_class("process"), &scon);
            if (rc == 0 && !strcmp(scon, mycon)) {
                ERROR("Warning!  Service %s needs a SELinux domain defined; please fix!\n", svc->name);
            }
            freecon(mycon);
            freecon(fcon);
            if (rc < 0) {
                ERROR("could not get context while starting '%s'\n", svc->name);
                return;
            }
        }
    }

    NOTICE("Starting service '%s'...\n", svc->name);

    pid_t pid = fork();
    if (pid == 0) {
        struct socketinfo *si;
        struct svcenvinfo *ei;
        char tmp[32];
        int fd, sz;

        umask(077);
        if (properties_initialized()) {
            get_property_workspace(&fd, &sz);
            snprintf(tmp, sizeof(tmp), "%d,%d", dup(fd), sz);
            add_environment("ANDROID_PROPERTY_WORKSPACE", tmp);
        }

        for (ei = svc->envvars; ei; ei = ei->next)
            add_environment(ei->name, ei->value);

        for (si = svc->sockets; si; si = si->next) {
            int socket_type = (
                    !strcmp(si->type, "stream") ? SOCK_STREAM :
                        (!strcmp(si->type, "dgram") ? SOCK_DGRAM : SOCK_SEQPACKET));
            int s = create_socket(si->name, socket_type,
                                  si->perm, si->uid, si->gid, si->socketcon ?: scon);
            if (s >= 0) {
                publish_socket(si->name, s);
            }
        }

        freecon(scon);
        scon = NULL;

        if (svc->ioprio_class != IoSchedClass_NONE) {
            if (android_set_ioprio(getpid(), svc->ioprio_class, svc->ioprio_pri)) {
                ERROR("Failed to set pid %d ioprio = %d,%d: %s\n",
                      getpid(), svc->ioprio_class, svc->ioprio_pri, strerror(errno));
            }
        }

        if (needs_console) {
            setsid();
            open_console();
        } else {
            zap_stdio();
        }

        if (false) {
            for (size_t n = 0; svc->args[n]; n++) {
                INFO("args[%zu] = '%s'\n", n, svc->args[n]);
            }
            for (size_t n = 0; ENV[n]; n++) {
                INFO("env[%zu] = '%s'\n", n, ENV[n]);
            }
        }

        setpgid(0, getpid());

        // As requested, set our gid, supplemental gids, and uid.
        if (svc->gid) {
            if (setgid(svc->gid) != 0) {
                ERROR("setgid failed: %s\n", strerror(errno));
                _exit(127);
            }
        }
        if (svc->nr_supp_gids) {
            if (setgroups(svc->nr_supp_gids, svc->supp_gids) != 0) {
                ERROR("setgroups failed: %s\n", strerror(errno));
                _exit(127);
            }
        }
        if (svc->uid) {
            if (setuid(svc->uid) != 0) {
                ERROR("setuid failed: %s\n", strerror(errno));
                _exit(127);
            }
        }
        if (svc->seclabel) {
            if (is_selinux_enabled() > 0 && setexeccon(svc->seclabel) < 0) {
                ERROR("cannot setexeccon('%s'): %s\n", svc->seclabel, strerror(errno));
                _exit(127);
            }
        }

        if (!dynamic_args) {
            if (execve(svc->args[0], (char**) svc->args, (char**) ENV) < 0) {
                ERROR("cannot execve('%s'): %s\n", svc->args[0], strerror(errno));
            }
        } else {
            char *arg_ptrs[INIT_PARSER_MAXARGS+1];
            int arg_idx = svc->nargs;
            char *tmp = strdup(dynamic_args);
            char *next = tmp;
            char *bword;

            /* Copy the static arguments */
            memcpy(arg_ptrs, svc->args, (svc->nargs * sizeof(char *)));

            while((bword = strsep(&next, " "))) {
                arg_ptrs[arg_idx++] = bword;
                if (arg_idx == INIT_PARSER_MAXARGS)
                    break;
            }
            arg_ptrs[arg_idx] = NULL;
            execve(svc->args[0], (char**) arg_ptrs, (char**) ENV);
        }
        _exit(127);
    }

    freecon(scon);

    if (pid < 0) {
        ERROR("failed to start '%s'\n", svc->name);
        svc->pid = 0;
        return;
    }

    svc->time_started = gettime();
    svc->pid = pid;
    svc->flags |= SVC_RUNNING;

    if ((svc->flags & SVC_EXEC) != 0) {
        INFO("SVC_EXEC pid %d (uid %d gid %d+%zu context %s) started; waiting...\n",
             svc->pid, svc->uid, svc->gid, svc->nr_supp_gids, svc->seclabel);
        waiting_for_exec = true;
    }

    svc->NotifyStateChange("running");
}

/* The how field should be either SVC_DISABLED, SVC_RESET, or SVC_RESTART */
static void service_stop_or_reset(struct service *svc, int how)
{
    /* The service is still SVC_RUNNING until its process exits, but if it has
     * already exited it shoudn't attempt a restart yet. */
    svc->flags &= ~(SVC_RESTARTING | SVC_DISABLED_START);

    if ((how != SVC_DISABLED) && (how != SVC_RESET) && (how != SVC_RESTART)) {
        /* Hrm, an illegal flag.  Default to SVC_DISABLED */
        how = SVC_DISABLED;
    }
        /* if the service has not yet started, prevent
         * it from auto-starting with its class
         */
    if (how == SVC_RESET) {
        svc->flags |= (svc->flags & SVC_RC_DISABLED) ? SVC_DISABLED : SVC_RESET;
    } else {
        svc->flags |= how;
    }

    if (svc->pid) {
        NOTICE("Service '%s' is being killed...\n", svc->name);
        kill(-svc->pid, SIGKILL);
        svc->NotifyStateChange("stopping");
    } else {
        svc->NotifyStateChange("stopped");
    }
}

void service_reset(struct service *svc)
{
    service_stop_or_reset(svc, SVC_RESET);
}

void service_stop(struct service *svc)
{
    service_stop_or_reset(svc, SVC_DISABLED);
}

void service_restart(struct service *svc)
{
    if (svc->flags & SVC_RUNNING) {
        /* Stop, wait, then start the service. */
        service_stop_or_reset(svc, SVC_RESTART);
    } else if (!(svc->flags & SVC_RESTARTING)) {
        /* Just start the service since it's not running. */
        service_start(svc, NULL);
    } /* else: Service is restarting anyways. */
}

void property_changed(const char *name, const char *value)
{
    if (property_triggers_enabled)
        queue_property_triggers(name, value);
}

static void restart_service_if_needed(struct service *svc)
{
    time_t next_start_time = svc->time_started + 5;

    if (next_start_time <= gettime()) {
        svc->flags &= (~SVC_RESTARTING);
        service_start(svc, NULL);
        return;
    }

    if ((next_start_time < process_needs_restart) ||
        (process_needs_restart == 0)) {
        process_needs_restart = next_start_time;
    }
}

static void restart_processes()
{
    process_needs_restart = 0;
    service_for_each_flags(SVC_RESTARTING,
                           restart_service_if_needed);
}

static void msg_start(const char *name)
{
    struct service *svc = NULL;
    char *tmp = NULL;
    char *args = NULL;

    if (!strchr(name, ':'))
        svc = service_find_by_name(name);
    else {
        tmp = strdup(name);
        if (tmp) {
            args = strchr(tmp, ':');
            *args = '\0';
            args++;

            svc = service_find_by_name(tmp);
        }
    }

    if (svc) {
        service_start(svc, args);
    } else {
        ERROR("no such service '%s'\n", name);
    }
    if (tmp)
        free(tmp);
}

static void msg_stop(const char *name)
{
    struct service *svc = service_find_by_name(name);

    if (svc) {
        service_stop(svc);
    } else {
        ERROR("no such service '%s'\n", name);
    }
}

static void msg_restart(const char *name)
{
    struct service *svc = service_find_by_name(name);

    if (svc) {
        service_restart(svc);
    } else {
        ERROR("no such service '%s'\n", name);
    }
}

void handle_control_message(const char *msg, const char *arg)
{
    if (!strcmp(msg,"start")) {
        msg_start(arg);
    } else if (!strcmp(msg,"stop")) {
        msg_stop(arg);
    } else if (!strcmp(msg,"restart")) {
        msg_restart(arg);
    } else {
        ERROR("unknown control msg '%s'\n", msg);
    }
}

static struct command *get_first_command(struct action *act)
{
    struct listnode *node;
    node = list_head(&act->commands);
    if (!node || list_empty(&act->commands))
        return NULL;

    return node_to_item(node, struct command, clist);
}

static struct command *get_next_command(struct action *act, struct command *cmd)
{
    struct listnode *node;
    node = cmd->clist.next;
    if (!node)
        return NULL;
    if (node == &act->commands)
        return NULL;

    return node_to_item(node, struct command, clist);
}

static int is_last_command(struct action *act, struct command *cmd)
{
    return (list_tail(&act->commands) == &cmd->clist);
}


void build_triggers_string(char *name_str, int length, struct action *cur_action) {
    struct listnode *node;
    struct trigger *cur_trigger;

    list_for_each(node, &cur_action->triggers) {
        cur_trigger = node_to_item(node, struct trigger, nlist);
        if (node != cur_action->triggers.next) {
            strlcat(name_str, " " , length);
        }
        strlcat(name_str, cur_trigger->name , length);
    }
}

void execute_one_command() {
    Timer t;

    char cmd_str[256] = "";
    char name_str[256] = "";

    if (!cur_action || !cur_command || is_last_command(cur_action, cur_command)) {
        cur_action = action_remove_queue_head();
        cur_command = NULL;
        if (!cur_action) {
            return;
        }

        build_triggers_string(name_str, sizeof(name_str), cur_action);

        INFO("processing action %p (%s)\n", cur_action, name_str);
        cur_command = get_first_command(cur_action);
    } else {
        cur_command = get_next_command(cur_action, cur_command);
    }

    if (!cur_command) {
        return;
    }

    int result = cur_command->func(cur_command->nargs, cur_command->args);
    if (klog_get_level() >= KLOG_INFO_LEVEL) {
        for (int i = 0; i < cur_command->nargs; i++) {
            strlcat(cmd_str, cur_command->args[i], sizeof(cmd_str));
            if (i < cur_command->nargs - 1) {
                strlcat(cmd_str, " ", sizeof(cmd_str));
            }
        }
        char source[256];
        if (cur_command->filename) {
            snprintf(source, sizeof(source), " (%s:%d)", cur_command->filename, cur_command->line);
        } else {
            *source = '\0';
        }
        INFO("Command '%s' action=%s%s returned %d took %.2fs\n",
             cmd_str, cur_action ? name_str : "", source, result, t.duration());
    }
}

static int wait_for_coldboot_done_action(int nargs, char **args)
{
    int ret;
    INFO("wait for %s\n", COLDBOOT_DONE);
    ret = wait_for_file(COLDBOOT_DONE, COMMAND_RETRY_TIMEOUT);
    if (ret)
        ERROR("Timed out waiting for %s\n", COLDBOOT_DONE);
    return ret;
}

/*
 * Writes 512 bytes of output from Hardware RNG (/dev/hw_random, backed
 * by Linux kernel's hw_random framework) into Linux RNG's via /dev/urandom.
 * Does nothing if Hardware RNG is not present.
 *
 * Since we don't yet trust the quality of Hardware RNG, these bytes are not
 * mixed into the primary pool of Linux RNG and the entropy estimate is left
 * unmodified.
 *
 * If the HW RNG device /dev/hw_random is present, we require that at least
 * 512 bytes read from it are written into Linux RNG. QA is expected to catch
 * devices/configurations where these I/O operations are blocking for a long
 * time. We do not reboot or halt on failures, as this is a best-effort
 * attempt.
 */
static int mix_hwrng_into_linux_rng_action(int nargs, char **args)
{
    int result = -1;
    int hwrandom_fd = -1;
    int urandom_fd = -1;
    char buf[512];
    ssize_t chunk_size;
    size_t total_bytes_written = 0;

    hwrandom_fd = TEMP_FAILURE_RETRY(
            open("/dev/hw_random", O_RDONLY | O_NOFOLLOW | O_CLOEXEC));
    if (hwrandom_fd == -1) {
        if (errno == ENOENT) {
          ERROR("/dev/hw_random not found\n");
          /* It's not an error to not have a Hardware RNG. */
          result = 0;
        } else {
          ERROR("Failed to open /dev/hw_random: %s\n", strerror(errno));
        }
        goto ret;
    }

    urandom_fd = TEMP_FAILURE_RETRY(
            open("/dev/urandom", O_WRONLY | O_NOFOLLOW | O_CLOEXEC));
    if (urandom_fd == -1) {
        ERROR("Failed to open /dev/urandom: %s\n", strerror(errno));
        goto ret;
    }

    while (total_bytes_written < sizeof(buf)) {
        chunk_size = TEMP_FAILURE_RETRY(
                read(hwrandom_fd, buf, sizeof(buf) - total_bytes_written));
        if (chunk_size == -1) {
            ERROR("Failed to read from /dev/hw_random: %s\n", strerror(errno));
            goto ret;
        } else if (chunk_size == 0) {
            ERROR("Failed to read from /dev/hw_random: EOF\n");
            goto ret;
        }

        chunk_size = TEMP_FAILURE_RETRY(write(urandom_fd, buf, chunk_size));
        if (chunk_size == -1) {
            ERROR("Failed to write to /dev/urandom: %s\n", strerror(errno));
            goto ret;
        }
        total_bytes_written += chunk_size;
    }

    INFO("Mixed %zu bytes from /dev/hw_random into /dev/urandom",
                total_bytes_written);
    result = 0;

ret:
    if (hwrandom_fd != -1) {
        close(hwrandom_fd);
    }
    if (urandom_fd != -1) {
        close(urandom_fd);
    }
    return result;
}

static int keychord_init_action(int nargs, char **args)
{
    keychord_init();
    return 0;
}

static int console_init_action(int nargs, char **args)
{
    char console[PROP_VALUE_MAX];
    if (property_get("ro.boot.console", console) > 0) {
        snprintf(console_name, sizeof(console_name), "/dev/%s", console);
    }

    int fd = open(console_name, O_RDWR | O_CLOEXEC);
    if (fd >= 0)
        have_console = 1;
    close(fd);

    fd = open("/dev/tty0", O_WRONLY | O_CLOEXEC);
    if (fd >= 0) {
        const char *msg;
            msg = "\n"
        "\n"
        "\n"
        "\n"
        "\n"
        "\n"
        "\n"  // console is 40 cols x 30 lines
        "\n"
        "\n"
        "\n"
        "\n"
        "\n"
        "\n"
        "\n"
        "             A N D R O I D ";
        write(fd, msg, strlen(msg));
        close(fd);
    }

    return 0;
}

static void import_kernel_nv(char *name, int for_emulator)
{
    char *value = strchr(name, '=');
    int name_len = strlen(name);

    if (value == 0) return;
    *value++ = 0;
    if (name_len == 0) return;

    if (for_emulator) {
        /* in the emulator, export any kernel option with the
         * ro.kernel. prefix */
        char buff[PROP_NAME_MAX];
        int len = snprintf( buff, sizeof(buff), "ro.kernel.%s", name );

        if (len < (int)sizeof(buff))
            property_set( buff, value );
        return;
    }

    if (!strcmp(name,"qemu")) {
        strlcpy(qemu, value, sizeof(qemu));
    } else if (!strncmp(name, "androidboot.", 12) && name_len > 12) {
        const char *boot_prop_name = name + 12;
        char prop[PROP_NAME_MAX];
        int cnt;

        cnt = snprintf(prop, sizeof(prop), "ro.boot.%s", boot_prop_name);
        if (cnt < PROP_NAME_MAX)
            property_set(prop, value);
    }
}

static void export_kernel_boot_props() {
    struct {
        const char *src_prop;
        const char *dst_prop;
        const char *default_value;
    } prop_map[] = {
        { "ro.boot.serialno",   "ro.serialno",   "", },
        { "ro.boot.mode",       "ro.bootmode",   "unknown", },
        { "ro.boot.baseband",   "ro.baseband",   "unknown", },
        { "ro.boot.bootloader", "ro.bootloader", "unknown", },
        { "ro.boot.hardware",   "ro.hardware",   "unknown", },
        { "ro.boot.revision",   "ro.revision",   "0", },
    };
    for (size_t i = 0; i < ARRAY_SIZE(prop_map); i++) {
        char value[PROP_VALUE_MAX];
        int rc = property_get(prop_map[i].src_prop, value);
        property_set(prop_map[i].dst_prop, (rc > 0) ? value : prop_map[i].default_value);
    }
}

static void process_kernel_dt(void)
{
    static const char android_dir[] = "/proc/device-tree/firmware/android";

    std::string file_name = android::base::StringPrintf("%s/compatible", android_dir);

    std::string dt_file;
    android::base::ReadFileToString(file_name, &dt_file);
    if (!dt_file.compare("android,firmware")) {
        ERROR("firmware/android is not compatible with 'android,firmware'\n");
        return;
    }

    std::unique_ptr<DIR, int(*)(DIR*)>dir(opendir(android_dir), closedir);
    if (!dir)
        return;

    struct dirent *dp;
    while ((dp = readdir(dir.get())) != NULL) {
        if (dp->d_type != DT_REG || !strcmp(dp->d_name, "compatible"))
            continue;

        file_name = android::base::StringPrintf("%s/%s", android_dir, dp->d_name);

        android::base::ReadFileToString(file_name, &dt_file);
        std::replace(dt_file.begin(), dt_file.end(), ',', '.');

        std::string property_name = android::base::StringPrintf("ro.boot.%s", dp->d_name);
        property_set(property_name.c_str(), dt_file.c_str());
    }
}

static void process_kernel_cmdline(void)
{
    /* don't expose the raw commandline to nonpriv processes */
    chmod("/proc/cmdline", 0440);

    /* first pass does the common stuff, and finds if we are in qemu.
     * second pass is only necessary for qemu to export all kernel params
     * as props.
     */
    import_kernel_cmdline(0, import_kernel_nv);
    if (qemu[0])
        import_kernel_cmdline(1, import_kernel_nv);
}

static int property_service_init_action(int nargs, char **args)
{
    /* read any property files on system or data and
     * fire up the property service.  This must happen
     * after the ro.foo properties are set above so
     * that /data/local.prop cannot interfere with them.
     */
    start_property_service();
    if (get_property_set_fd() < 0) {
        ERROR("start_property_service() failed\n");
        exit(1);
    }

    return 0;
}

static int signal_init_action(int nargs, char **args)
{
    signal_init();
    if (get_signal_fd() < 0) {
        ERROR("signal_init() failed\n");
        exit(1);
    }
    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 selinux_init_all_handles(void)
{
    sehandle = selinux_android_file_context_handle();
    selinux_android_set_sehandle(sehandle);
    sehandle_prop = selinux_android_prop_context_handle();
}

static bool selinux_is_disabled(void)
{
    if (ALLOW_DISABLE_SELINUX) {
        if (access("/sys/fs/selinux", F_OK) != 0) {
            // SELinux is not compiled into the kernel, or has been disabled
            // via the kernel command line "selinux=0".
            return true;
        }

        char tmp[PROP_VALUE_MAX];
        if ((property_get("ro.boot.selinux", tmp) != 0) && (strcmp(tmp, "disabled") == 0)) {
            // SELinux is compiled into the kernel, but we've been told to disable it.
            return true;
        }
    }

    return false;
}

static bool selinux_is_enforcing(void)
{
    if (ALLOW_DISABLE_SELINUX) {
        char tmp[PROP_VALUE_MAX];
        if (property_get("ro.boot.selinux", tmp) == 0) {
            // Property is not set.  Assume enforcing.
            return true;
        }

        if (strcmp(tmp, "permissive") == 0) {
            // SELinux is in the kernel, but we've been told to go into permissive mode.
            return false;
        }

        if (strcmp(tmp, "enforcing") != 0) {
            ERROR("SELinux: Unknown value of ro.boot.selinux. Got: \"%s\". Assuming enforcing.\n", tmp);
        }
    }
    return true;
}

int selinux_reload_policy(void)
{
    if (selinux_is_disabled()) {
        return -1;
    }

    INFO("SELinux: Attempting to reload policy files\n");

    if (selinux_android_reload_policy() == -1) {
        return -1;
    }

    if (sehandle)
        selabel_close(sehandle);

    if (sehandle_prop)
        selabel_close(sehandle_prop);

    selinux_init_all_handles();
    return 0;
}

static int audit_callback(void *data, security_class_t /*cls*/, char *buf, size_t len) {
    snprintf(buf, len, "property=%s", !data ? "NULL" : (char *)data);
    return 0;
}

static void selinux_initialize() {
    Timer t;

    selinux_callback cb;
    cb.func_log = selinux_klog_callback;
    selinux_set_callback(SELINUX_CB_LOG, cb);
    cb.func_audit = audit_callback;
    selinux_set_callback(SELINUX_CB_AUDIT, cb);

    if (selinux_is_disabled()) {
        return;
    }

    INFO("Loading SELinux policy...\n");
    if (selinux_android_load_policy() < 0) {
        ERROR("SELinux: Failed to load policy; rebooting into recovery mode\n");
        android_reboot(ANDROID_RB_RESTART2, 0, "recovery");
        while (1) { pause(); }  // never reached
    }

    selinux_init_all_handles();
    bool is_enforcing = selinux_is_enforcing();
    INFO("SELinux: security_setenforce(%d)\n", is_enforcing);
    security_setenforce(is_enforcing);

    NOTICE("(Initializing SELinux took %.2fs.)\n", t.duration());
}

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);

    // 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.
    mkdir("/dev", 0755);
    mkdir("/proc", 0755);
    mkdir("/sys", 0755);

    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);

    // Indicate that booting is in progress to background fw loaders, etc.
    close(open("/dev/.booting", O_WRONLY | O_CREAT | O_CLOEXEC, 0000));

    // 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 started!\n");

    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();

    selinux_initialize();

    // 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");

    property_load_boot_defaults();

    init_parse_config_file("/init.rc");

    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_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");
    queue_builtin_action(property_service_init_action, "property_service_init");
    queue_builtin_action(signal_init_action, "signal_init");

    // 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");

    // TODO: why do we only initialize ufds after execute_one_command and restart_processes?
    size_t fd_count = 0;
    struct pollfd ufds[3];
    bool property_set_fd_init = false;
    bool signal_fd_init = false;
    bool keychord_fd_init = false;

    for (;;) {
        if (!waiting_for_exec) {
            execute_one_command();
            restart_processes();
        }

        if (!property_set_fd_init && get_property_set_fd() > 0) {
            ufds[fd_count].fd = get_property_set_fd();
            ufds[fd_count].events = POLLIN;
            ufds[fd_count].revents = 0;
            fd_count++;
            property_set_fd_init = true;
        }
        if (!signal_fd_init && get_signal_fd() > 0) {
            ufds[fd_count].fd = get_signal_fd();
            ufds[fd_count].events = POLLIN;
            ufds[fd_count].revents = 0;
            fd_count++;
            signal_fd_init = true;
        }
        if (!keychord_fd_init && get_keychord_fd() > 0) {
            ufds[fd_count].fd = get_keychord_fd();
            ufds[fd_count].events = POLLIN;
            ufds[fd_count].revents = 0;
            fd_count++;
            keychord_fd_init = true;
        }

        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);

        int nr = poll(ufds, fd_count, timeout);
        if (nr <= 0) {
            continue;
        }

        for (size_t i = 0; i < fd_count; i++) {
            if (ufds[i].revents & POLLIN) {
                if (ufds[i].fd == get_property_set_fd()) {
                    handle_property_set_fd();
                } else if (ufds[i].fd == get_keychord_fd()) {
                    handle_keychord();
                } else if (ufds[i].fd == get_signal_fd()) {
                    handle_signal();
                }
            }
        }
    }

    return 0;
}