Android Installd 分析

struct cmdinfo cmds[] = {
{ "ping", 0, do_ping },
{ "create_app_data", 7, do_create_app_data },
{ "restorecon_app_data", 6, do_restorecon_app_data },
{ "migrate_app_data", 4, do_migrate_app_data },
{ "clear_app_data", 5, do_clear_app_data },
{ "destroy_app_data", 5, do_destroy_app_data },
{ "move_complete_app", 7, do_move_complete_app },
{ "get_app_size", 6, do_get_app_size },
{ "get_app_data_inode", 4, do_get_app_data_inode },
{ "create_user_data", 4, do_create_user_data },
{ "destroy_user_data", 3, do_destroy_user_data },
//odex 优化
{ "dexopt", 10, do_dexopt },
{ "markbootcomplete", 1, do_mark_boot_complete },
{ "rmdex", 2, do_rm_dex },
{ "freecache", 2, do_free_cache },
{ "linklib", 4, do_linklib },
{ "idmap", 3, do_idmap },
{ "createoatdir", 2, do_create_oat_dir },
{ "rmpackagedir", 1, do_rm_package_dir },
{ "clear_app_profiles", 1, do_clear_app_profiles },
{ "destroy_app_profiles", 1, do_destroy_app_profiles },
{ "linkfile", 3, do_link_file },
{ "move_ab", 3, do_move_ab },
{ "merge_profiles", 2, do_merge_profiles },
{ "dump_profiles", 3, do_dump_profiles },
{ "delete_odex", 3, do_delete_odex },
};

启动service installd 守护程序
service installd /system/bin/installd
 class main 
 socket installd stream 600 system system

参考system/core/init/init.cpp代码
int main(int argc, char** argv) {
.................
const BuiltinFunctionMap function_map;
Action::set_function_map(&function_map);
Parser& parser = Parser::GetInstance();
parser.AddSectionParser("service",std::make_unique<ServiceParser>());
parser.AddSectionParser("on", std::make_unique<ActionParser>());
parser.AddSectionParser("import", std::make_unique<ImportParser>());
parser.ParseConfig("/init.rc");
ActionManager& am = ActionManager::GetInstance();
am.QueueEventTrigger("early-init");
..........................
// Trigger all the boot actions to get us started.
am.QueueEventTrigger("init");
.........................
std::string bootmode = property_get("ro.bootmode");
if (bootmode == "charger") {
am.QueueEventTrigger("charger");
} else if (strncmp(bootmode.c_str(), "ffbm", 4) == 0) {
NOTICE("Booting into ffbm mode\n");
am.QueueEventTrigger("ffbm");
} else {
am.QueueEventTrigger("late-init");
}
// Run all property triggers based on current state of the properties.
am.QueueBuiltinAction(queue_property_triggers_action, "queue_property_triggers");
...............................
}

文件
system/core/init/builtins.cpp
定义builtin_functions
BuiltinFunctionMap::Map& BuiltinFunctionMap::map() const {
    constexpr std::size_t kMax = std::numeric_limits<std::size_t>::max();
    static const Map builtin_functions = {
        {"bootchart_init",          {0,     0,    do_bootchart_init}},
        {"chmod",                   {2,     4,    do_chmod}},
        {"chown",                   {2,     5,    do_chown}},
        {"class_reset",             {1,     1,    do_class_reset}},
        {"class_start",             {1,     1,    do_class_start}},
        {"class_stop",              {1,     1,    do_class_stop}},
        {"copy",                    {2,     2,    do_copy}},
        {"domainname",              {1,     1,    do_domainname}},
        {"enable",                  {1,     1,    do_enable}},
        {"exec",                    {1,     kMax, do_exec}},
        {"export",                  {2,     2,    do_export}},
        {"hostname",                {1,     1,    do_hostname}},
        {"ifup",                    {1,     1,    do_ifup}},
        {"init_user0",              {0,     0,    do_init_user0}},
        {"insmod",                  {1,     kMax, do_insmod}},
        {"installkey",              {1,     1,    do_installkey}},
        {"load_persist_props",      {0,     0,    do_load_persist_props}},
        {"load_system_props",       {0,     0,    do_load_system_props}},
        {"loglevel",                {1,     1,    do_loglevel}},
        {"mkdir",                   {1,     4,    do_mkdir}},
        //mount 分区
        {"mount_all",               {1,     kMax, do_mount_all}},
        {"mount",                   {3,     kMax, do_mount}},
        {"umount",                  {1,     1,    do_umount}},
        {"powerctl",                {1,     1,    do_powerctl}},
        {"restart",                 {1,     1,    do_restart}},
        {"restorecon",              {1,     kMax, do_restorecon}},
        {"restorecon_recursive",    {1,     kMax, do_restorecon_recursive}},
        {"rm",                      {1,     1,    do_rm}},
        {"rmdir",                   {1,     1,    do_rmdir}},
        {"setprop",                 {2,     2,    do_setprop}},
        {"setrlimit",               {3,     3,    do_setrlimit}},
        {"start",                   {1,     1,    do_start}},
        {"stop",                    {1,     1,    do_stop}},
        {"swapon_all",              {1,     1,    do_swapon_all}},
        {"symlink",                 {2,     2,    do_symlink}},
        {"sysclktz",                {1,     1,    do_sysclktz}},
        {"trigger",                 {1,     1,    do_trigger}},
        {"verity_load_state",       {0,     0,    do_verity_load_state}},
        {"verity_update_state",     {0,     0,    do_verity_update_state}},
        {"wait",                    {1,     2,    do_wait}},
        {"write",                   {2,     4,    do_write}},
    };
    return builtin_functions;
}

static int do_mount_all(const std::vector<std::string>& args) {
    std::size_t na = 0;
    bool import_rc = true;
    bool queue_event = true;
    int mount_mode = MOUNT_MODE_DEFAULT;
    const char* fstabfile = args[1].c_str();
    std::size_t path_arg_end = args.size();

    for (na = args.size() - 1; na > 1; --na) {
        if (args[na] == "--early") {
             path_arg_end = na;
             queue_event = false;
             mount_mode = MOUNT_MODE_EARLY;
        } else if (args[na] == "--late") {
            path_arg_end = na;
            import_rc = false;
            mount_mode = MOUNT_MODE_LATE;
        }
    }

    int ret =  mount_fstab(fstabfile, mount_mode);

    if (import_rc) {
        /* Paths of .rc files are specified at the 2nd argument and beyond */
        import_late(args, 2, path_arg_end);
    }

    if (queue_event) {
        /* queue_fs_event will queue event based on mount_fstab return code
         * and return processed return code*/
        ret = queue_fs_event(ret);
    }

    return ret;
}

/* Imports .rc files from the specified paths. Default ones are applied if none is given.
 *
 * start_index: index of the first path in the args list
 */
static void import_late(const std::vector<std::string>& args, size_t start_index, size_t end_index) {
    Parser& parser = Parser::GetInstance();
    if (end_index <= start_index) {
        // Use the default set if no path is given
        static const std::vector<std::string> init_directories = {
            "/system/etc/init",
            "/vendor/etc/init",
            "/odm/etc/init"
        };

        for (const auto& dir : init_directories) {
            parser.ParseConfig(dir);
        }
    } else {
        for (size_t i = start_index; i < end_index; ++i) {
            parser.ParseConfig(args[i]);
        }
    }
}

程序入口
int main(const int argc, char *argv[]) {
return android::installd::installd_main(argc, argv);
}

static int installd_main(const int argc ATTRIBUTE_UNUSED, char *argv[]) {
    char buf[BUFFER_MAX];
    struct sockaddr addr;
    socklen_t alen;
    int lsocket, s;
    int selinux_enabled = (is_selinux_enabled() > 0);

    setenv("ANDROID_LOG_TAGS", "*:v", 1);
    android::base::InitLogging(argv);

    ALOGI("installd firing up\n");

    union selinux_callback cb;
    cb.func_log = log_callback;
    selinux_set_callback(SELINUX_CB_LOG, cb);

    if (!initialize_globals()) {
        ALOGE("Could not initialize globals; exiting.\n");
        exit(1);
    }

    if (initialize_directories() < 0) {
        ALOGE("Could not create directories; exiting.\n");
        exit(1);
    }

    if (selinux_enabled && selinux_status_open(true) < 0) {
        ALOGE("Could not open selinux status; exiting.\n");
        exit(1);
    }
    //定义服务端socket，与客户端通讯
    lsocket = android_get_control_socket(SOCKET_PATH);
    if (lsocket < 0) {
        ALOGE("Failed to get socket from environment: %s\n", strerror(errno));
        exit(1);
    }
    if (listen(lsocket, 5)) {
        ALOGE("Listen on socket failed: %s\n", strerror(errno));
        exit(1);
    }
    fcntl(lsocket, F_SETFD, FD_CLOEXEC);

    for (;;) {
        alen = sizeof(addr);
        s = accept(lsocket, &addr, &alen);
        if (s < 0) {
            ALOGE("Accept failed: %s\n", strerror(errno));
            continue;
        }
        fcntl(s, F_SETFD, FD_CLOEXEC);

        ALOGI("new connection\n");
        for (;;) {
            unsigned short count;
            if (readx(s, &count, sizeof(count))) {
                ALOGE("failed to read size\n");
                break;
            }
            if ((count < 1) || (count >= BUFFER_MAX)) {
                ALOGE("invalid size %d\n", count);
                break;
            }
            if (readx(s, buf, count)) {
                ALOGE("failed to read command\n");
                break;
            }
            buf[count] = 0;
            if (selinux_enabled && selinux_status_updated() > 0) {
                selinux_android_seapp_context_reload();
            }
            if (execute(s, buf)) break;
        }
        ALOGI("closing connection\n");
        close(s);
    }

    return 0;
}

}  // namespace installd
}